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| hee ON THE Pp; Z
anal RED. A fua
FOSSIL FISHES OF THE CARBONIFEROUS |

LIMESTONE SERIES

OF

GREAT BP 3h

BY

JAMES W. @AVie, 2 Ge
Pratns XLT. to LXY.

[FROM THE SCIENTIFIC TRANSACTIONS OF THE ROYAL DUBLIN SOCIETY. VOL. 1. SER, IL]

 

DUBLIN.

PUBLISHED BY THE ROYAL DUBLIN SOCIETY.

PRINTED BY ALEX. THOM & CO., 87, 88, & 89, ABBEY-STREET,
THE QUEEN’S PRINTING OFFICE.
FOR HER MAJESTY’S STATIONERY OFFICE.

 

SEPTEMBER, 1883.
''PALEONTOLOGY -TIBRARK

Cid. om, aeparnLe
VAR 4-Cl

 

 

 
'' 

XXV.—ON THE FOSSIL FISHES OF THE CARBONIFEROUS LIMESTONE
SERIES OF GREAT BRITAIN. By James W. Davis, r.as., &c. &e. Wir
' Puates XLIT. to LXV. (Communicatep By tae Haru or ENNISKILLEN).

 

(Read May 15th, 1882.)

 

CONTENTS.
1. Explanatory preface, . : : j Page 327
2. Classified description of the fossil fishes, : . 20
3. Description of localities, ees : : ‘aa 03D
4, List of genera and species with localities, : » O49
5. Description of Plates, . . : : Oe
6. Index to genera and species, . : : wy vor

1. EXPLANATORY PREFACE.

The observations and descriptions contained in the following pages have been
based on material derived principally from the magnificent collection of the Earl
of Enniskillen, at Florence Court, Jreland; a collection far transcending all others,
not only in the extent and rarity of its contents, but in the number of unique
specimens which it contains. Since the commencement of this memoir, the
collection has been removed to the new Natural History Department of the British
Museum at South Kensington, where it will, conjointly with the twin collection of
the late Sir Philip de Malpas Grey Egerton, Bart., form an unrivalled exposition
of the Ichthyic fauna of the past ages of the globe. It is fitting that the results of
the unremitting labours of the two noble ichthyologists, pursued in happy unison
during half a century, should find a home in the national collection.

The collections at the British Museum; the Museum of the Geological Society,
Burlington House; the Museum ‘at Bristol ; the Dublin Museum; the Wood-
wardian Museum at Cambridge; the Museum of the Philosophical Society at
York ; the Museum at Clifton College, Bristol, and others, have been most kindly
placed at my disposal, and, where necessary, specimens from those co:lections have
been lent for illustration.

It is with great pleasure that I express my indebtedness to those gentlemen who
have aided my researches, amongst whom I may name, I hope, without any
invidious distinction, my friends Dr. Woodward and Mr. R. Etheredge, Dr. E.
Perceval Wright, of Dublin ; Prof. Hughes, of Cambridge; Prof. Sollas, of Bristol,
and Dr. Grenfall, of Clifton College; Dr. Reed, of York, (who by his recent gifts of his

TRANS, ROY. DUB, SOC.) WN.S,, VOL. I. Bak

131
''828 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

own and the late Mr. Wood’s collections, to the York Museum, has set an example
worthy of emulation), Mr. William Horne, of Leyburn, in Wensleydale, to whose
rich private collection I have had free access. To Mr. Walter Keeping, at the
Woodwardian Museum, and his son, Mr. W. Keeping, at York, [ am obliged for
kindly rendered attentions, and to Mr. W. Percy Sladen, ny dear friend and near
neighbour, for help not easily expressed in words—to many others my thanks are
due and heartily tendered.

To Lord Enniskillen, without whose aid this memoir would have been well nigh
impossible, I cannot sufficiently express my sense of obligation. His great and
practical knowledge of the fossils in his collection ; his intimate intercourse with
that learned ichthyologist, the author of “ Poissons Fossiles,” and the knowledge
his lordship possessed of the unpublished researches of M. Agassiz, have, in some
‘departments, rendered my labour comparatively easy, whilst the genial and kindly
friendship always exhibited has rendered my work at all times most agreeable.

2. CLASsIFIED DescRIPTioN oF THE Fossit FISHES.
PIsces.

I4 is proposed in the following descriptions to adopt the classification recently
(1880) published by Dr. Albert C. L. G. Giinther in his “ Introductory Study of
Fishes.” The class Pisoxs is divided into four sub-classes, viz.:—

I. Paleeichthytes.

II. Teleostei = Teleostei (Huxley).
III. Cyclostomata — Marsipobranchii (Huxley).
IV. Leptocardii = Pharyngobranchii (Huxley).

The fishes of the Mountain Limestone formations belong exclusively to the
first sub-class which is defined as follows by Dr. Giinther.

I, PAL#ICHTHYTES.
Heart with a contractile conus arteriosus ; intestine with a spiral valve; optic

nerves non-decussating, or only partially decussating ; skeleton cartilaginous or osseous.

This sub-class is divided into two orders, viz.:—the Chondropterygii and the
Ganoide. The former being equivalent to the Hlasmobranchiw (Bonaparte) of
Professor Huxley’s classification, and including the sharks, rays, and chimeras.
The latter embraces the orders Ganoidei and Dipnoi of Professor Huxley.

Order 1. CHONDROPTERYGII.

“Skeleton cartilaginous. Body with median and paired fins, the under pair

 
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain, 329

abdominal. Vertebral column generally heterocercal, the upper lobe of the caudal
fin produced. Gills attached to the skin by the outer margin, with several inter-
vening oil] openings ; rarely one external gill opening only. No gill cover. Noair
bladder. Two, three, or more series of valves in the conus arteriosus. Ova large
and few in number, impregnated, and in some species developed, within an
uterine cavity. Embryo with deciduous external gills. Males with intromittent
organs attached to the ventral fins.’—(Giinther.)

This order is divided into two sub-orders: Plagiostomata and Holocephala ; the
first comprising the sharks and rays; the second, the chimeras.

Sub-order 1. Puaciosromata.

“From five to seven gill openings. Skull with a suspensorium and the palatal
apparatus detached. ‘Teeth numerous.”—(G'iinther. )

The Plagiostomata may be divided into two groups, the (A) Selachoidet or sharks,
whose body is elongate, more or less cylindrical, gradually passing into the tail ;
gill openings lateral,

The (B) Latordez or rays, in which the body is depressed, and surrounded by
immensely developed pectoral fins, forming a broad flat disc. Caudal portion more
or less rapidly contracted to form the tail. Guill openings, five in number, are
always placed on the abdominal aspect of the fish.

The fish-remains found in the Mountain Limestone formations have hitherto not
proved very numerous, nor have they been discovered in a great number of
localities, considering the large area occupied by this group of rocks, its great
vertical thickness, and the large extent to which it has been excavated for com-
mercial purposes. The Limestone in the great majority of localities does not
appear to contain any remains of fishes, and with the exception of the Armagh
district and that of Bristol, other localities, including Wensleydale, Kendal,
Derbyshire, and Oreton in Salop, have added few, either specimens or species, to
enrich the knowledge of the ichthyic fauna of that ancient period.

The fish-remains hitherto found in the Carboniferous or Mountain Limestone,
belong with few exceptions to the Plagiostomata—the sharks and rays—and consist
of an almost endless variety of teeth, and a large number of spines. A very slight
consideration of the anatomical constitution of an existing shark will give an
idea of the difficulty attending the determination of the species of the several
fossils, and still more of the almost utter impossibility of reconstructing,on a sufficiently
certain and scientific basis, anything approaching a correct idea of the form and
parts of the extinct fish. In existing sharks the whole framework of the body is
frequently cartilaginous. The skull and mandible are well developed, but are entirely
composed of cartilage ; the pectoral and pelvic arches are the same ; the vertebree

are in many fishes cartilaginous, in others a slight ring of bone is embedded in the
812
''330 On the Fossil Fishes of the Carboniferous. Limestone Serics of Great Britain.

vertebrze and there is further modification in the direction of a completely osseous
centrum. The teeth, the spines placed in front of the dorsal or pectoral fins.or
other parts of the body, and the dermal tubercles or shagreen, are the only parts
of the fishes which are composed of an osseous or other hard substance which would
be capable of resisting speedy decomposition after death. As might be naturally
inferred, these are the only parts of the fishes of Carboniferous age which are found
fossil ; even the vertebree appear to have been entirely devoid of calcareous deposit
and with the remaining cartilaginous portions of the fish have been decomposed and
lost. The cartilaginous framework which held the teeth and spines together having
decayed, these less destructible organs speedily became separated, and may have
been carried considerable distances apart by currents or tides before they were eventu-
ally embedded. It is an extremely rare occurrence to find the various teeth, spines,
and dermal tubercles, in such relationship that they can be identified as belonging
to the same fish. Not only is this the case with the separated spines and teeth,
but the greatest confusion may, and no doubt does to a large extent, exist in the
determination of the many forms of teeth, and it may easily happen that the teeth
which have lain side by side in the palate of one fish, may be considered by the
ichthyologist as representing not only different species but present so marked differ-
erfées in form as to lead to their being placed under separate genera. An interest-
ing example of this kind, in which the two genera Cochliodus and Helodus, instituted
by Professor Agassiz, though they had been found in several countries in Europe as
well as in America, and for more thanthirty years considered as separate genera, were
ultimately found, by the fortunate discovery of a specimen with the teeth undis-
turbed, to be one and the same genus.* The organs on which modern classifica-
tion is based :—the non-decussating optic nerves ; the muscular conus arteriosus
with its varied rows of valvular openings; and the spiral valve of the intestine,
have no existence in a fossil state, and it is only by analogy thatit can be reasoned
that as in recent fishes it is found that certain functional relations exist between
the soft and the hard parts of the fishes, so having procured the hard bony csjecta
membra of the extinct fishes, and these exhibiting certain relationships with the
recent forms, it may be inferred that the more perishable portions have also borne
a similar relationship to those of recent forms.

The fishes of the Mountain Limestone, excepting Ganoids, are comprised in the
sub-order Plagicstomata of Giinther, which includes the sharks and rays, but
excludes the chimeroid: fishes, and for this reason the sub-order as defined by Dr.
Giinther is perhaps preferable to the Elasmobranchii of Professor Huxley in con-
sidering the fishes of Carboniferous age ; the Chimeree being of Jurassic, Cretaceous,
and Tertiary age, unless the bones described by Newberry in “ The Geology of Ohio,”
Vol. 1., page 307, as Rhynchodus should be proved to carry the origin of the
group so far back as Carboniferous times.

*« Geological Survey of Illinois,” Vol. I1., pp. 88-89.

 

 
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 331

The Plagiostomatous fishes may be conveniently divided into six groups fox the
purposes of the present work, viz.:—

I. Hybodontidee.—Type, Ctenacanthus.
II. Orodontidee.—Type, Orodus.
III. Petalodontide.—Type, Petalodus.
IV. Cochliodontidze.—Type, Cochliodus.
V. Psammodontide.—Type, Psammodus.
VI. Copodontide.—Type, Copodus.

The first group (Hybodontidee) comprises the spines of Ctenacanthus and probably
some others. From the great resemblance of Ctenacanthus with Hybodus it has
been recognised by the late Sir P. Egerton and others as a Hybodont and arranged
accordingly. The teeth of Hybodus are well known, many specimens having been
discovered in the Lias of Lyme Regis, which have proved conclusively their connec-
tion with the spines. The teeth and spines of Ctenacanthus have not been so found,
but judging from analogy it appears probable that the teeth of Cladodus may have
been associated with the spines of Ctenacanthus. Except that the Cladodi are more
formidable and that the coronal prominences are more prominent, they bear a close
resemblance to the teeth of Hybodus.

The Orodontide comprise a group of teeth related to the existing Cestracionts,
but in several essential respects differing from them, as will be stated more fully

 

hereafter.

The Petalodontidze will embrace the genera defined by Messrs. Newberry and
Worthen in the synopsis of the Petalodont genera (“ Geol. Survey, Ilinois,” Vol. IL.,
p- 31) with the addition of some genera not included by those authors. | This group
has generally been considered by various authors as more or less associated with the
family of Cestracionts, but, as will be seen, there are reasons why it should be
removed from this association, and may be considered as possessing sufficiently
distinct and characteristic features to render necessary the constitution of a separate
family, as indicated by Messrs. Newberry and Worthen. The peculiar arrangement
of teeth and their apparent relationship to Janassa of Miinster also confirms this
separation, and may indicate an evolutional passage between the sharks and the
rays. The large and beautiful series of the teeth of the Petalorhynchus in the
collection of the Earl of Enniskillen have rendered possible this generalization, and
to Lord Enniskillen is due the credit of having suggested the relationship of the
genus to Janassa.

The Cochliodontidee embraces an interesting and most peculiar series of forms of
dentition. In many respects it presents resemblances to the palates of the existing
Cestracion, but it is difficult to conceive that the numerous teeth of Cestracion
should be very closely related to the single enrolled tooth of some Cochliodonts.
The point of resemblance consists in the cartilaginous jaw being enveloped in each
''332 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

instance by a pavement-like surface of crushing teeth. As will be seen, however,
there appears to be a wide difference in the process of growth as well as form, and
when it is remembered that magnificent, almost perfect, palates of Agassizodus have
been found in the Carboniferous Measures of illinois, described by Messrs. St. John
and Worthen (“Geol. Survey of Illinois,” Vol. VI., p. 311), and comprising a variety
of teeth closely resembling those of Orodus, which are arranged almost exactly as
are those of the existing Cestracion, little doubt can be entertained that there is in
the Cochliodonts a group of fishes whose representatives have long ceased to exist,
and which must stand apart and alone in ichthyic development.

Besides the Psammodontidz, represented by the well-known Psammodus, the
Copodontidee comprise a large assemblage of more or less flat pavement-like teeth
from the Armagh limestone. This large assemblage, the result of many years most
painstaking collection, is quite unique. In no other locality does it appear that teeth
of similar import have been discovered. They have remained in the collection of Lord
Enniskillen, undescribed to the present time. Professor Agassiz, during a visit to
Florence Court nearly twenty-five years ago, carefully examined the collection and
distributed the specimens amongst a number of new genera and species, to which
he appended names in manuscript. These have been retained in the following
pages in every possible instance. ,

Some light is thrown on the dentition of Psammodus by specimens in the Bristol
Museum, and it appears probable that the idea given by M. de Koninck (“ Faune
du Calc. Carbon. de la Belgique,’ p. 42) of the dentition of Psammodus may
prove the correct one.

A, Selachoidet.
Family —Hybodontidee, Agass.

“Two dorsal fins, each with a serrated spine. Teeth rounded, longitudinally
striated, with one larger and from two to four smaller lateral cusps. Skin covered
with shagreen.”—(Giinther.)

Genus——Ctenacanthus, Agass.

Ctenacanthus—A gassiz, L., 1833. ‘Recher. Poiss. Foss.,” Vol. III., p. 10.
M‘Coy, I, 1855. ~“ Brit. Paleeoz. Foss.,” p. 624.

2)

“Fin-spines, of moderate or large size, compressed, gradually tapering, moderately
arched backwards ; anterior face narrow, rounded; posterior face concave, with a
moderate cavity, the lateral edges bordered by two rows of curved denticles
inclined downwards. Surface marked with strong, longitudinal ridges and furrows,
pectinated by transverse scales or tubercles. The concealed base of moderate size,
rapidly tapering, finely striated.” —(M‘Coy.)

 

 
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britaan. 338

The genus Ctenacanthus is confined to the strata below the Coal Measures, just as
the genus Hybodus has only been found in the rocks above. The two genera are
very similar in form, and the fishes which were possessed of the spines were evi-
dently closely related in structure and habits. Prof. Agassiz (“ Poiss. Foss.,” Vol.
IIT., p. 171) considered that the spines of Ctenacanthus and the teeth of Psammodus
might have belonged to the same fish, but the discovery of the teeth of Hybodus in
close relationship to the position of the spines, has proved beyond doubt that the
teeth of that- genus bear a close relationship to the pointed cutting teeth of the
sharks of the existing species, having a central prominent pointed cone with smaller
lateral ones rising from a broad expanded base. The occurrence in considerable abun-
dance of the teeth of Cladodus in the Carboniferous rocks, similar in form to those
of the known Hybodus, renders the probability great, that Ctenacanthus was pro-
vided with teeth possessing similar characters to those of Hybodus and that the
spine of Ctenacanthus and the teeth of Cladodus may have been from the same
fish, though no positive proof exists of the relationship.

The Agassizian conception of the genus Ctenacanthus has been enlarged by various
authors so as to include a number of specimens, hike Ctenacanthus (%) distans, M‘Coy,
which it is very probable pertained to quite a different type of fish. The inclusion
of such species has been also made by some American paleontologists, as for instance,
C.. gracillimus (‘Geological Survey of Illinois,” Vol. IL, p. 126, pl. xii, fig. 3),
C. burlingtonensis and C. keokuk, St. J. and W. (‘“‘Illinois,” Vol. VI., pp. 426, 427,
pl. xv., figs. 7, 8), and others. These specimens differ in no respect from some which
have been described as Leptacanthus, Ag. (compare C. gracillimus with L. occidentalis,
op. cit. pl. xii., fig. 2) and Acondylacanthus, St. J. and W., whilst they present
great divergence from the Ctenacanthoid type. A chief characteristic of the
latter is the large open posterior groove or pulp cavity extending the whole length
of the osseous base and in a few instances still further up the spine. This feature
appears tobeentirely absent in the long graceful spines indicated above. In the large
series from the Armagh limestone there is no evidence of such a cavity opening
posteriorly, the internal cavity is terminal and is open only at the end of the base
of the spine. After searching through the descriptions of American paleontologists
a similar result is obtained. In nearly all cases the basal end is fractured or
wanting. This difference may possibly be of even greater than generic importance,
and may indicate affinities rather with the Batoidei than the Selachoidei. In the
following descriptions it is proposed to remove the variety of spines indicated trom
the genus Ctenacanthus, and, for reasons hereafter adduced, to place them with the
so-called Carboniferous Leptacanths in the genus Acondylacanthus of Messrs. St. John
and Worthen ; retaining only such species in the genus Ctenacanthus as will fall in
with the description of them indicated by Professor Agassiz.
''334 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

Ctenacanthus major, A gass.
(Pl, KLIL,; figs: 1,2.)

Ctenacanthus major—L. Agassiz, 1637. “Rech: Poss. Foss.” Vol TIT, p. 10; pl. av.

5 s C. G. Giebel, 1848. “Fauna der Vorwelt,” Vol. I., pt. 3, p. 308.

me y H. G. Brown, 1848. ‘Nomencl. Paleont.,” p. 355.

i 3 s 1849. “Enumerator Palont.,” p. 649.

, 5 F. J. Pictet, 1854. “Traité de Paléont.,” Vol. 1I., p. 290.

ss 3 J. Morris, 1854. _ “Catal. Brit. Foss.,” p. 323.

s Morris and Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. XVIII. p. 100.

5 z Young and Armstrong, 1871. “Trans. Geol. Soc., Glasgow,” Vol. IIT., Supplet.
p. 70.

Z z ceed eerie \ 1876. “Catal. West. Scot. Foss,” p. 61.

os . J. J. Bigsby, 1878. ‘Thesaurus Devon.-Carb.,” p. 351.

This spine is described by M. Agassiz as being elegantly arched in the form of a
scythe. it attains a length of nearly two feet and is about three inches in diameter
at the base. From the base it contracts insensibly towards the superior extremity,
ending in a fine point. The surface is ornamented by a large number of small
longitudinal ridges with intermediate rounded grooves. The ridges are divided by
closely-imbricating obliquely transverse folds, which project over the groove on each
side and form a denticulated margin. On the posterior surface of the spine, but
only near the point, there extends a double row of small denticles. The latter are
rounded, recurved towards the base, and pointed. The sides of the spine are com-
pressed, but slightly rounded midway betwixt back and front. The transverse section
is oval (P]. XLII, fig. 1a), rounded posteriorly, and somewhat sharply accuminate
anteriorly. The line of demarcation between the exposed part of the spime and the
smooth base which was embedded in the flesh, is very oblique. A deep and open
cavity extends along the posterior face. It is prolonged in the form of an enclosed
oval cavity almost to the apical extremity of the spine.

If the size of the fish, to which these spines belonged, is proportionate to the size
of living species which are possessed of dorsal spines, it must be admitted that it
attained to gigantic proportions, and is, perhaps, the largest example of Ichthyo-
dorulite occurring in the Paleozoic rocks of this country. Itis extremely probable
that Ctenacanthus had two spines, one each before the anterior and posterior dorsal '
fins. Itis known that such was the case in Hybodus, as well as several other
Selachoids which occur in a fossil state, and as found in the dog-fish existing on our
own coasts at the present day. The spine represented on Pl. XLII, fig. 2, was
probably in front of the second one, (Pl. XLIL, figure 1), which is slightly shorter,
and broader and has a more robust character.

The spines of this genus bear a marked resemblance to Ctenacanthus maximus,
described L. G. de Koninck (“ Faune du Calcaire Carbonifére de la Belgique,” Pt. I.

 

 
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 335

p. 68, pl. vii., fig. 1), both on account of their size, their general form and the
character of their external decoration. The description of the spines given by Dr. de
Koninek is almost identical with that of Professor Agassiz, in the ‘‘Poissons Fossiles,”
of the Bristol species, except that the transverse section is more decidedly oval and
is not so sharply produced anteriorly. This character, however, is not of sufficient
importance to form a specific difference, but, not having had an opportunity to
examine the Belgian species, I do not feel justified in placing it definitely with
Ctenacanthus major, Ag.

Formation and locality : Mountain Limestone, Bristol.
Ez coll. 1. Earl of Enniskillen ; 2. Bristol Museum.

Ctenacanthus tenuistriatus, Agass.

(Pl. XIE; fee: 25 28)

Ctenacanthus tenuistriatus—L. Agassiz, 1837. “ Poiss, Foss.,” Vol. I11.,p. 11, pl, i, figs, 7-11.
ie - P. deM. Grey Egerton, 1839. “Catalogue of Fossil. Fish.”
3 ; C. G. Giebel, 1848, “ Fauna der Vorwelt,” Bd.I., Abth., ITI., p. 308.
; H. G. Bronn, 1848. ‘‘Nomencl. Paleont.,” p. 355,
. J. Morris, 1854. “Cat. British Foss.,” p. 323.
F. J. Pictet, 1854. “ Traité de Paleont.,” Vol. IT., p. 290.

Morris and Roberts, 1862. “ Quar.Jour., Geol. Soc.,” Vol. X VIII., p. 100.

P. de M. Grey Egerton, 1869. “ Catal. Type Specimens of Fossil Fishes,” p.5.

Young & Armstrong, 1871. “Transactions Geological Society, Glasgow,”
Vol. III., Supplement, p. 70.

o ” TE Coe \ 1876. “Catalogue of the West. Scot. Fossils,” p. 61.
. . J.J. Bigsby, 1878. “Thesaur. Devon.-Carb.,” p. 351.

L. G. de Koninck, 1878, “Annales de Musée Royal dhistoire naturelle
de Belgique,” Vol. II., p. 67, pi. vii, fig. 2.

Spine, of moderate size, a perfect specimen being fourteen to fifteen inches in
length, greatest breadth two inches. The specimens described by Prof. Agassiz
were very imperfect, and afforded insufficient material for a complete description.
The lower portion of the spine is almost straight, with a very slight curvature back-
wards; base rounded; the upper part, about one-fourth the length of the whole,
contracts rapidly in diameter, posterior surface deeply curved, and terminating
with an acutely pointed apex. It is this portion of the spine which is represented
in the “Poissons Fessiles,’ Vol IIL, pl. iii., fig. 7. The lateral surfaces are compressed
and covered with minute longitudinal strize, with intervening grooves, about the
same width as the ridges. The ridges increase in number towards the base, by
bifurcation. Each ridge is characterized by minute transverse foldings of the
surface. This species differs considerably from C. major, Ag., in the paucity of the
ridges, not only are the longitudinal ridges more slender than those of C. major,
but those towards the posterior portion of the surface are considerably finer and

smaller than those on the anterior surface. The anterior border is well rounded,

TRANS. ROY. DUB. SOC., N.S, VOL. I. oF 1
''336 On the Fossil Lishes of the Carboniferous Limestone Series of Great Britain.

the surface striz are large and broad, and in some instances, almost smooth. The
base is divided from the exposed portion of the spine by an oblique line, and
occupies about one-fourth of the entire length of the spine. An open cavity extends
from the base towards the superior extremity of the spine. It is not so deep as in
the majority of the species of Ctenacanthus, but it remains open to a higher point
than in any other species, and only the uppermost fourth of the spine is enclosed.
A transverse section exposes a small cavity in proportion to the thickness of the
‘Spine ; towards the base the anterior wall of the spine is very thick ; higher in the
‘spine, the internal canal presents the form of a much compressed oyal, but still
‘nearer the apex the section is less compressed.

The specimen described by M. de Koninck from the neighbourhood of Felay, in
Belgium, appears to differ from the Bristol specimens in the longitudinal strize
being broader and less numerous, and in the possession of posterior denticles of

which there is no evidence in the Bristol type.

Formation and locality : Mountain Limestone, Bristol.
Ex coll, Earl of Enniskillen.

Ctenacauthus heterogyrus, Agass., M8,
(Ei. ALY. fios.1, 2573")

‘Ctenacanthus heterogyrus—L. Agassiz, 1837. “ Rech. Poiss. Foss.,” Vol. 1IL., p. 177 (ind).
oF Portlock, J. E., 1848. ‘Rep. Geol. Survey, Fermanagh, d&c.,” p. 461.
3 . Giebel, C. G., 1848. “Fauna der Vorwelt,” Vol. I., pt. 3, p. 309.
a Bronn, Hie G.. 1848. “Nomencl. Paleont.,” p. 355.
e - a 1849. ‘ Enumerator Paleont.,” p. 649.
‘ Morris, J., 1854. “Cat. Brit. Foss.,” p. 325.
i és Pictet, EF. J., 1854. ‘“ Traité de Paléont.,” Vol. I1., p. 290.
A . M‘Coy, F., 1855. ‘Brit. Puleeoz. Foss.,” p. 625, pl. 31, fig. 32.
2 is Morris and Roberts, 1862. “Quart. Jour. Geol. Soc.,” Vol. XVIII. p. 100.
- . Bigsby, J. J., 1878. ‘Thesaurus Devon.-Carb.,” p. 351.
7 3 De Koninck, L. G., 1878. *‘ Faune Cale. Carb. de la Belgique,” p. 66, pl. vii.,
fig. 3.

This species, named by Prof. Agassiz, but not described, was described by Prof.
‘MCoy in the following terms:—“ Very short, rapidly tapering ; length of exposed
portion three inches, at which length it forms an obtuse point, from a width at base
of ‘5 inch (measured at right angles to the length), very slightiy arched, the
posterior outline nearly straight, the anterior one convex. Sides flattened,
converging to the narrow anterior face, which is occupied by a flattened smooth
ridge about twice as wide as those of the sides; lateral ridges extremely irre-
gular in size, shape and marking; rather thick, separated by deep sulci less than
half their width; ridges averaging four in two lines, at four lines in diameter,
some of them thinning out above at irregular distances, other pairs uniting branch-
wise into one above, some appearing to taper to both ends; most of the ridges are
nearly smooth in a great part of their course, or showing a more or less distinct
crenulation on their sides (about three in the space of one line), from small opposite

 

 
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 337°

lateral tubercles ; in certain irregular spots these lateral tubercles increase in size
and strength, and distinctly cross the ridges by becomiug connected across them ;
in several of the ridges, particularly towards the base, the transverse tuberculation
and notching becomes so distinct, that the ridge is separated into a row of
triangular tubercles about half a line long.

“The extreme irregularity of the ridges of this species, no two of them being
quite alike, and several of them totally changing their aspect after short distances,
easily distinguish this species from its congeners. The finely striated base is of
rather small size, and rapidly tapering, the line of separation between it and the
ridged exterior being very oblique.”

The specimens which served Prof. M‘Coy as types for this species, appear from the
figures which he has given to have consisted of a few detached fragments of the
spines. Since that description was written, many specimens have been obtained from
the limestone at Armagh, and I am enabled to give drawings of perfect specimens,
by the kindness of Lord Enniskillen. The specimen (Pl. XLIV., fig. 1) is five
inches in length, its greatest breadth being ‘8 of an inch, from which point it tapers.
in either direction, gradually, towards the superior extremity, ending in an acute
point, and more rapidly towards the base, which is obtusely rounded. The exposed
portion of the surface, extends three inches from the point along the anterior
margin and is divided from the base by an oblique line, extending to the posterior:
margin, which it reaches at a distance of 2°2 inchesfrom the apex. The base is smooth,
or finely striated and occupies an area almost equal to that of the exposed part.
Along the posterior margin, on each side, there is a row of obtusely rounded denticles..

A peculiarity not observed by M‘Coy in the arrangement of the longitudinal
ridges is, that they extend parallel with the pcsterior margin, which is almost
straight, whilst those nearer the front of the spine run out along the anterior margin.

Formation and locality: Mountain Limestone, Armagh.
Lx coll, Karl of Enniskillen.

Ctenacanthus brevis, Agass.
(Pl, XLIIL, fig. 3.)
Ichthyodorulithes brevis, Buckl. and De la Beche (MS8.)

Ctenacanthus brevis—L. Agassiz, 1837: * Rech» Poiss.: Foss,” Vol. ITL., p. 11, pl. i1., fig, 2.
a 5 C. G. Giebel, 1848. “Fauna der Vorwelt,” Vol. IL. p. 309.
s i H. G. Bronn, 1848. “ Nomencl. Paleont.,” p. 355.
rf -- 4) 1849. ‘ Enumerator Paleont.,” p. 649.
e cs F. J. Pictet, 1854. ‘‘Traité de Paléont.,” Vol. II., p. 290.
F a J. Morris, 1854. “Catal. Brit. Foss.,” p. 323.
3 Morris and Roberts, 1862. “Quart. Jour. Geol. Soc.,” Vol. XVIIL, p. 100,
es ‘: Youngand Armstrong, 1871. “Trans. Geol.Soc., Glasgow,” Vol. IIL, Supt.p. 70,
» i Sassen 18%6.., “ Catal, Wests, Scot, Foss,,"p1 61,
5 » J.J. Bigsby, 1878. “Thesaurus Devon.-Carb.,” p. 351.

8K 2
''838 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

Prof. Agassiz in his description of this spine says, “ I know as yet only one figure
of this spine, which has been communicated to me by Dr. Buckland, and which I
have had copied in the plate cited above. There is represented the inferior part of
a large spine, very thick in proportion to its length, of which the exposed surface
is covered with small transversely striated tubercles, disposed in longitudinal and
parallel series. ‘The base is smooth; the line of demarcation between the part
embedded and that which was exposed is very oblique, and arched towards the
anterior margin. The posterior basal cavity is very large and deep.”

A perfect specimen in the cabinet of the Earl of Enniskillen is nine inches in
lencth ; the greatest breadth is 1°4 inches, at the junction of the exposed and
basal portions. The posterior face is almost straight, except for a short length
near the superior extremity, which is deeply curved. The anterior margin is
eracefully arched from the apex to the base. The proportion of the spine which
was embedded in the body of the fish is extremely large, and forms about two-
thirds of the whole surface. The smooth base extends 4°5 inches along the anterior
surface, from which it extends, with a very oblique curvature, to 15 inches from
the point on the posterior surface. ‘There is no appearance of posterior denticles.

This species in some respects bears a close resemblance to Ctenacanthus
spectabilis, St. John and Worthen, (‘Geological Survey of Illinois,’ Vol. Vi,
p. 420, pl. vi. fig. 1). In the latter, however, the base is much smaller in proportion
to the exposed part of the spine, and the angle dividing the two is not nearly so
oblique as in C. brevis, Ag. The peculiar way in which the cost are deflected
towards the posterior margin in the Kinderhook specimen, does not occur in the
Armagh one, and the form of the tubercles set along the costz of the two species
is quite distinct.

Formation and locality : Mountain Limestone, Armagh.

Ex coll, Earl of Enniskillen.

Ctenacanthus denticulatus, M‘Coy.
CPL SUEY. tie. £)

Ctenacanthus denticulatus—F. M‘Coy, 1848. “Ann. and Mag. Nat. Hist.,” 2nd Ser., Vol. IT.,p, 116,
. J. F. Pictet, 1854. “'Traité de Paléont.,” Vol. II., p. 290.
cr ‘3 J. Morris, 1854. ‘Catal. Brit. Foss.,” p. 323.
5 - F. Moy, 1855. “ Brit. Paleoz. Foss.,” p. 625, pl. 3 K, fig. 16.
J. J. Bigsby, 1878. ‘“ Thesaur. Devon.-Carb.,” p. 351.

“Spine, nearly straight, slightly curved towards the apex; length of naked
portion 5°5 inches, length of the rapidly tapering base two inches, width near base,
nine lines; section truncato-elliptical, sides slightly convex, front narrow,
rounded ; posterior face wide, depressed, concave at both sides, with an obtuse ridge ~
in the middle, the lateral angles closely set with a row of numerous, small, conical,
downward-curved teeth on each, their own length apart; longitudinal ridges

 
''On the Fossil Fishes of the Carboniferous Limestone Scries of Great Britain, 339

rounded, less than their own diameter apart (about four in two lines in the middle
of the ray); they are a little wider at base than towards the apex, increasing in
number downward by dichotomy ; the sides of each ridge are denticulated, with
sharp recurved teeth extending half way across the intervening spaces, the denticle
of one side connected with its fellow on the other by a slightly oblique fold across
the ridge, each pair being separated from that above and below by about the
thickness of the ridge; near the posterior margin on each side are four or five
ridges much smaller than the rest, crossed by oblique blunt tubercles.” —M‘Coy.

The ornamentation of the longitudinal ridges of this species bears a great
resemblance to that of Ctenacanthus gradocostus, St. J. and W. (“ Geol. Survey of
Illinois,” Vol. VL, p.425, pL. xv., figs. 2, 3); a reference to the enlarged drawing of the
costee, loc. cit. pl. xv., fig. 3b, and comparison with Pl. XLIV., fig. 4a, representing the
present species, will render this more clear than description. The ridges of the
Quincy specimen are triangular in section, whilst those of C. denticulatus are
rounded. The general form and character of the two species are similar as far as
can be gathered from the imperfect specimens figured and described by Messrs. St.
John and Worthen.

Formation and locality : Dark shale above the Yellow Sandstone of Monaduff, Drumlist, N. Ireland.
Ex coll, Woodwardian Museum, Cambridge.

Ctenacanthus limaformis, Davis.

(Pl, XLV, ia 5)

Spine, medium size, robust and strong, diameter large in proportion to its length.
Specimen imperfect, a small part of the superior extremity is missing as well as a
larger part of the base. The anterior margin of the spine is arched slightly, and
along the whole of the exposed portion is a board band of ganoine divided into
small filelike segments, which appears to be the peculiar characteristic of this
species. The length of the part preserved is 4°50 inches.

Locality and formation : Mountain Limestone, Bristol.
Ex coll, Earl of Enniskillen.

Ctenacanthus salopiensis, Davis.

(PL X LIV. fies 6.)

Fin spine, when perfect about ten inches in length, and at its broadest part 1°8
inches in diameter. The base or part buried in the integument is large in propor-
tion to the remainder, being nearly one-third the length of the spine. Its anterior
margin curves rapidly towards the end and is 2°5 inches in length, the posterior is
4°5 inches and considerably straighter. The line dividing the base from the upper
portion of the spine is very oblique. The exposed part is slightly curved towards
the apex principally along its anterior margin. In transverse section the spine is
triangularly elliptical, widest from back to front, much compressed at the sides ;
the posterior diameter is greater than the anterior, the latter almost pointed. The
''340 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

anterior surfaces are much compressed and ornamented by numerous longitudinal
ridges ; very small and separated by furrows their own diameter in width. Both
the ridges and furrows are largest near the base, towards the apex of the spine they
decrease considerably in size especially along the posterior margin, into which they
are ultimately absorbed and disappear. The furrows are deep in proportion to their
width ; there are about forty on each side. ‘ransversely across the ridges there
extend minute plica or folds, these are continued down each side of the ridge and
join, at the base of the furrow, a similar fold from the side of the opposite ridge.
Each separate ridge has the appearance of a long string of minute cups the narrow
base of each being placed in the extended mouth of the one preceding it, and when
highly magnified presenting an extremely beautiful appearance. ‘The anterior face
of the spine is slightly rounded. but accuminate and is not characterized by any
' peculiarity in the ridges which continue to cover it. A wide and deep open cavity
occupies the lewer posterior portion of the spine ; about equidistant between the
base and apex this becomes enclosed and extends far towards the latter. The
enclosed cavity is very large and the sides of the spine forming its walls are pro-
portionately thin. The teeth extending along the postero-lateral angles are not
preserved with sufficient distinctness to be described, though the broken stumps
are distinguishable, the teeth having been broken away with the matrix.

The ornamentation of the ridges of this species bears a slight resemblance to
that of C. crenatus, Ag., or C. denticulatus, M‘Coy. In the former the crenulations
are formed by a row of small transverse tubercles extending obliquely down the
sides of the ridges and rarely passing over its summit, whilst in C. denticulatus the
sides of the ridge are denticulated with sharp recurved teeth extending half
way across the intervening hollow, and slightly connected across the ridge. The
characters of both are sufficiently distinct from the species now described, even if the
general form of the spine was less distinct in each case, whilst near the same length
as C.denticulatus, it is double its breadth, and there are considerably more than double
the number of ridges on each lateral surface. Ctenacanthus speciosus, St. John
and Worthen (“Geological Survey of Illinois,” Vol. VI, p. 424, pl. xiv., figs.
8, 4), appears to be closely related to this species. It may be distinguished by
the lateral striation being closer, with narrower interspaces, and the transverse
ornamentation of the ridges not extending so far across the intermediate furrow.

Locality : The specimen described is from Oreton in Salop. Specimens have also been found at Bristol

which possess the same characters and are without doubt the same species ; they are, however, of a some-

what stronger and more robust appearance than the Salopian specimens.—All are from the Mountain
Limestone.

Ha coll. Ear) cf Enniskillen.

Ctenacanthus dubius, Davis.
(Pi, XY fie. 7.)

A spine 2°5 inches in length, and ‘5 of an inch in greatest breadth. Slightly
curved on the posterior margin, considerably more so on the anterior one. The

 
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain, 341

base occupies nearly one-fourth the length of the spine. The spine is crushed and
a part of the base has disappeared ; from the widest part, a little higher than the
line dividing the base from the exposed part of the spine, it becomes rapidly
narrower and ends in a fine point. The sides are divided into six or eight striae,
not so broad as the intervening hollows; the striz are simple and coated with
enamel.

Locality : Armagh, Mountain Limestone.
Hx coll. The Earl of Enniskillen.

Ctenacanthus levis, Davis.
(cl Adv, Gol.)

Fin spine, about five inches in length and at its broadest part ‘6 of an inch wide,
From the oblique basal line it tapers with a gradually diminishing diameter to an
obtuse point. The spine is gently but decidedly curved in outline : elliptical in trans-
verse section. ‘The lateral faces are much compressed, and are covered with longitu-
dinal ridges, extending from the basal line parallel to the posterior margin towards
the point. The ridges are most numerous near the base where the spine is broadest,
and become fewer by running into, and being absorbed by, a median ridge stronger
than the others and forming a keel along the anterior margin the whole length of
the exposed part of the spine. The ridges, twenty-four in number at the base, are
wider than the intermediate furrows, and present a broad flattened surface of shining
enamel. The relative size of the coste and intercostal spaces 1s maintained through
the whole length of the spine, being equally wide near the apex as atthe base. The
base of the spine is comparatively small, of the usual fibrous structure ; the line
dividing it from the exposed portion is straight and forms a very obtuse angle to
the longitudinal axis of the spine. A deep channel extends along the basal portion,
which becomes enclosed and forms an internal cavity extending nearly to the apex
of the spine. ‘The cavity is oval in section and is situated nearer the posterior than
‘the anterior surface, equidistant from the sides. Along the posterior surface there
extends a deep circular groove, the postero-lateral angles of which are armed for
some distance below the apex with recurved, rounded, sharply-pointed denticles
separated by spaces about double their own diameter. Lower down, the angles are
devoid of denticles, somewhat more rounded, and quite smooth.

This form of spine is comparatively rare, the specimen of which a figure is given
is imperfect, the apex being broken off and a portion of the base fractured. Other
examples are slightly more curved than the spine described, but are otherwise in all
respects characterized by the same peculiarities. The difference in convexity may
be a little irregularity, and due to there having been a spine in front of each of the

two dorsal fins, one having been before the anterior and the other the postericr
-dorsal fin. |
''842 On the Fossil Fishes of the Carboniferous Inmestone Series of Great Britain.

A transverse section of this species gives a triangle whose sides are connected by
a base much shorter, and in this respect it is distinguished from Ctenacanthus
plicatus, next described, in which the section forms an almost equilateral triangle. .

Locality ; Mountain Limestone of Armagh,
Ex coll, Earl of Enniskillen.

Ctenacanthus plicatus, Agass.

(Pl. XLV, fig. 4.)

Onchus plicatus—L. Agassiz, 1833; .‘‘ Réch. sur les Poiss, Foss.,” Vol. TIL, p. 177 Gnd).
. - J. E. Portlock, 1843. ‘ Rept. on Geol. Fermanagh, &c.,” p. 461.
a , C. G. Giebel, 1848. ‘Fauna der Vorwelt,” Vol. J., pt. 3, p. 302.
$3 5S H. G. Bronn, 1848. ‘ Nomencl. Paleont.,” p. 843.
as es 1849. ““ Enumerator Paleont.,” p. 652.
. F, J. Pictet, 1854. ‘ Traité de Paléont.,” Vol. IL, p. 284.
Ns 5 J. Morris, 1854. ‘Catal. Brit. Foss.,” p. 334.
i 5 Morrisand Roberts, 1862. ‘Quart. Jour. Geol. Soc.,” Vol. XVIII. p. 101.
ie i J.J. Bigsby, 1878. <‘Thesaur. Devon.-Carb.,” p. 359.

Spine, medium size, slightly curved, rather rapidly tapering towards the point,
imperfect ; length preserved three inches, probable length when perfect about 4°5
to 5 inches, greatest diameter at line of insertion ‘65 of an inch ; base, osseous,
striated, one-fourth the entire length of the spine: line dividing base and exposed
surface, oblique, with convexity towards the base. Transverse section, triangular,
sides acuminate above, base curved inwards, two-thirds the length of one side.
Lateral surface covered by a number of broad plicated ridges, at 1°7 inches from
the base, nine or ten in number, increasing by dichotomy to more than double that
number towards the base, and apparently decreasing upwards. A_ peculiarity in
the ridges of this species consists in their first dichotomizing, and then the two
branches lower down coalescing with the ridges on either side of them, to become
again separated a quarter of an inch nearer the base.” A representation of this
peculiarity is given on Plate XLV., fig. 4a. The sides are very flat, meeting anteriorly
at a sharp angle without median keel, the anterior margin being formed by the
repeated inosculation of the lateral ridges. The latter present a steep, almost
perpendicular face towards the anterior margin, whilst in the opposite direction
they slope gradually downwards, presenting something like the appearance of
overlapping tiles; a series of minute striations traverse the ridges in an oblique line
parallel with that of the base. Posterior surface hidden by the matrix.

This spine was named by Prof. Agassiz, Onchus plicatus, and is the type specimen
from the late Admiral Jones’ collection. ‘the specimen which is described above as
Ctenacanthus levis, was also named in MS, as belonging to the same species, in
the collection of the Earl of Enniskillen, The principal characteristic given by
Prof. Agassiz to distinguish Ctenacanthus from Onchus is that it is possessed of
posterior denticles, the latero-posterior angles of Onchus being smooth and free from
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 348

teeth. In the specimen from the Enniskillen collection the posterior margin is
exposed and a row of recurved teeth is very clearly exhibited. Unfortunately the
specimen forming the type of Agassiz is buried in a hard matrix and the posterior
margin cannot be seen, but the two are so clearly related and possess so
mary features in common than it is very probable, could the surface be exposed
without too great risk to the specimen that it would be found to possess posterior
denticles. After careful consideration it appears advisable to consider the specimen as
belonging to the genus Ctenacanthus.

The more rapidly contracting form of this species, the absence of an anterior
median keel, and the peculiarities of the ridges, separate it specifically from Ctena-
canthus levis.

Formation and locality : Mountain Limestone, Armagh.
Ex coll. Geological Society’s Museum.

Ctenacanthus sulcatus, Agass.
(Pl. XLV., fig. 3.)
Ichthyodorulithes bristoliensis, Buck. and De la Béche (MS.)

Onchus sulcatus—L,. Agassiz, 1833. “Rech. Poiss. Foss.,” Vol. IIL, p. 8, pl.'l, fig. 6.
ss : C. G. Giebel, 1848. ‘ Fauna der Vorwelt,” Vol. 1., pt. 3, p. 302,
35 5 Ht. G. Bronn, 1848. “ Nomencl. Paleont.,” p. 843.
. a 4 1849. “ Hnumerator Paleont.,” p. 652.
s F. J. Pictet, 1854, “ Traité de Paléont.,” Vol. II, p. 284.
s a J. Morris, 1854. . “Catal. Brit. Foss.,” p.. 334.
» se Morris and Roberts, 1862. “Quart. Jour. Geol. Soc.,” Vol. AV INE, oy 103.
= vs J. J. Bigsby, 1878. ‘Thesaurus Devon.-Carb.,” p. 359.

Spine, more or less arched, medium size, perfect example five to six inches in
length, breadth 1-0 inch, gradually tapering towards the point, base one-fourth the
length of the spine, division between base and exposed part forms a slightly sig-
moidal curvature: transverse section oval, much compressed laterally ; internal
cavity situated near posterior surface, comparatively small and broad. The lateral
surfaces are ornamented by peculiar longitudinal ridges, which are described by
Prof. Agassiz as being especially distinguished by the irregularity of their furrows
and of the ribs which separate them, some of them being double the width of
others ; they, however, have all a very flat surface. The anterior surface is formed
by a broad ridge which is divided near the base into three branches, it is rounded
and more thickly coated with enamel than the lateral ridges. The posterior cavity
is large, and open at the basal extremity, a deep groove being continued on the ex-
ternal surface towards the apex of the spine. It appears doubtful whether gspeci-
inens of this species have been found which exhibit the latero-posterior angles
with sufficient clearness to show the posterior denticles. Prof. Agassiz states that
Dr. Buckland sent to him a drawing of a specimen, well preserved, from which it
appeared that the spine had a double row of small denticles along the superior

TRANS. ROY, DUB, SOC., N.S., VOL. I, 31,
''344 On the Fossil Fishes of the Carboniferous Limestone Series of Great Brituin.

portion of the posterio margins. Dr. Buckland also stated in a manuscript des-
eription of the spine that there appeared on its posterior surface, two rows of regular
tubercles. Prof. Agassiz considers that the denticles may be merely due to the
termination of the longitudinal furrows. After some hesitation, however, he placed
the spine in the genus Onchus, at the same time recognizing its resemblance to
Hybodus.

After careful study of specimens, there appears sufficient evidence of posterior
denticles ; and the close resemblance, and evident relationship to the species forming
the genus Ctenacanthus, renders necessary its removal to that genus.

This species bears some resemblance to C. /evis and C. plicatus, from the latiter it
will be distinguished by its greater breadth and its greatly compressed oval section,
and from the former by the longitudinal ridges on each side, which in C. levis run
parallel with the posterior margin and in C. sulcatus with the anterior one.

Formation and locality : Carboniferous Limestone, Bristol.
Ex coll. Bristol Museum.

Ctenacanthus pustulatus, Davis.
(el ALY. 29,2.)

Length of spine nearly four inches, greatest width at the base of the exposed part
‘sof aninch. The spine is slightly curved, the anterior border more so than the pos-
terior. The base extends 1°4 inches along the posterior border, and 1:2 of the anterior
one is occupied by it. The remaining portion of the spine contracts gradually to a
point and is covered with longitudinally arranged striz, most numerous at the base
of the exposed portion and diminishing in number towards the apex, not by anasto-
mosing but by the gradual thinning out and disappearance of the ridges The
surface of the strize or ridges is coated with ganoine and is quite smooth ; along the
posterior part of the spine they are about the same diameter as the intermediate
hollows, but near the anterior portion the hollows occupy a greater space than the
ridges. The hollows are covered by numerous pittings arranged in lorgitudinal
rows parallel to their own direction, and there are also in the most anterior ones
several detached ganoine-tipped pustules rising to a level with the ridges. The
lateral surface is slightly compressed, rather more so towards the posterior border.
Along the whole length of the posterior margin there is a double row of hooks or
small denticles, broad at the base, culminating in an obtuse point.

- Locality : Mountain Limestone of Armagh,
Ex coll. Karl of Enniskillen.

 

 

 
''On the Fossil Fishes of the Carboniferous Limestone Serics of Great Britain. 345

Ctenacanthus crenulatus, Agass., MS.

(Pl. XLY., fig. 6.)

Ctenacanthus crenulatus—L. Agassiz, 1833.“ Rech. Poiss. Foss.,” Vol. III., p. 177.
e . J. E. Portlock, 1843. ‘Geol. Report, Londonderry, &c.,” p. 461.
> Ji C. G. Giebel, 1848. ‘“ Fauna der Vorwelt,” Vol. I., pt. 3."p. 309.
S - i, G. Bronn, 1848. “ Nomencl. Paleont.,” p. 355.
5 a . 1849. ‘ Enumerator Paleont.,” p. 649,
§ y J. Morris, 1854. “Catalogue Brit. Foss.,” p. 323.
5 - F. J. Pictet. 1854,“ Traité de Paléont.,” Vol. IL, p. 290.
Re crenatus— F. M’Coy, 1855. |“ Brit. Paleoz, Foss.,” p. 624, 3, 1., fig. 31.

crenulatus—Morris and Roberts, 1862. “ Quart. Jour. Geol. Soc.,” Vol. XVIIL., p- 100.

2?

This specimen, which was then a part of the collectionof Admiral J ones, M.P., served
as the type of this species, was named but not described by Prof. Agassiz. The
following is the description in the “ Paleozoic Fossils” :—Fin-spine, gradually taper-
ing, moderately compressed, sides rather flattened, converging to a narrow, rounded,
anterior face: each side with about ten or eleven, nearly equal, regular, rounded
ridges, parted by sulci, about their own width apart, (at six lines wide there are five
ridges in two lines) each ridge with a row of small transverse tubercles, strongly
crenating the sides, down which they extend obliquely; those of each side usually
opposite, but sometimes alternate, generally leaving the middle of each ridge smooth,
but occasionally in some spots the small tubercles from each side of a ridge meet on
the middle, forming transversely rhomboidal tubercles, attenuated at the lateral
extremities : five lateral tubercles in the space of one line. The posterior cavity is
rather large.

‘The length of this species is unknown, but it is probably at least four inches,
The species is easily recognised by the regular ridges being crenulated, or milled,
like the edge of a coin, by the small elongate tubercles, projecting at right angles
from the sides of the ridge, and usually not encroaching on its centre.” —(M‘Coy.)

During a recent visit to Cambridge, I was unable to find the specimen which was
the type of this genus. It may and in all probability was, described from the
private collection of Admiral Jones, and afterwards consigned to some other col-
lection ; perhaps lost.

Locality and formation: Mountain Limestone, Armagh.
Ex coll. Woodwardian Museum, Cambridge

Ctenacanthus rectus, Agass. MS.
(Ply, ae |

Onchus rectus—L. Agassiz, 1833. “Rech. sur les Poiss. Foss.,” Vol. III., p. 177.
My 3 J. E. Portlock, 1843. ‘Geol. Report, Londonderry, &.,” p. 461.
Bs $3 C. G. Giebel, 1848. ‘Fauna der Vorwelt,” Vol. I, pt. 3, p. 302,
2 e H. G. Bronn, - 1848. ‘“Nomencl. Paleont.,” p. 843,
- - AS 1849. ‘ Enumerator Palzont.,” p- 652.
a i J. Morris, 1854. “Catal. Brit. Foss.,” p. 334.
- i F. J. Pictet, 1854. “Traité de Paléont.,” Vol. IL., p. 284.

3 - Morris and Roberts, 1862.  “ Quart. Journ. Geol, noe.” Vol. VILE me Tal

ia
''346 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

The type of this species is in the museum of the Geological Society, London, in
the collection presented by Admiral Jones. It is an imperfect spine, 1°25 inches in
length, ‘2 inch broad, and tapering to a point. The basal portion is wanting, and
the specimen appears to be the superior extremity of a specimen perhaps three
or four inches long when perfect. Its sides are ornamented by smooth, longi-
tudinal ridges; a larger one forming a carina along the anterior margin. Be-
tween the ridges are spaces wider than the ridges, in the flat bases of which are
a number of minute strize running parallel with the ridges. The spine is enveloped
in the matrix, and the form of a section is not perceptible.

This little specimen appears to be unique. It was apparently considered by
Prof. Agassiz to be an Onchus, and was named by that learned ichthyologist
O. rectus. There is, however, no visible characteristic which will distinguish it
from Ctenacanthus ; and as in all probability posterior denticles exist, but are
hidden by the matrix, it is thought better to include the specimen in this genus.

Formation and locality : Mountain Limestone, Armagh.
Lx coll. Geological Society’s Museum, London.

Genus—Acondylacanthus, St. John and Worthen.

Leptacanthus—L. Agassiz, 1833. ‘* Poiss. Foss.,” p. 176. MS_, (partim.)
3 EF. M‘Coy, 1855. ‘Brit. Paleeoz. Fossils,” p. 633.
Ctenacanthus (partim)—F. M‘Coy, 1855. “ Brit. Paleoz. Foss.,” p. 625.

Leptacanthus—Newberry and Worthen, 1866. “ Paleont. Illinois,” Vol. II., p. 116.
Acondylacanthus—St. John and Worthen, 1875. “ Paleont. Illinois,” Vol. VI., p. 432.

“Fin-rays, long, gradually tapering, laterally compressed, and moderately curved
posteriorly. Lateral faces longitudinally fluted, the costz being smooth (or
crenulated) and enamelled, increasing by occasional bifurcation, perhaps more rarely
by implantation. Posterior face uniformly excavated longitudinally, apparently
without median keel; postero-lateral angles bearing a row of downward-hooked
denticles, which extend in the majority of species well towards the base. Pulp cavity
occupying the posterior half or more of the spine. Base unknown.”—(S¢é. J. and W.)

Prof. Agassiz, in his work “ Poissons Fossiles,” Vol. III, p. 27, has instituted the
genus Leptacanthus, comprising several species of Ichthyodorulites from the Jurassic
formation, including the Lias. They are long and slender spines; sides longitu-
dinally striated, latero-posterior margins armed with teeth, and the anterior edge
sharp and keeled; base not known, but probably like Hybodus.

In the same work, page 176, Prof. Agassiz gives the name Leptacanthus priscus
to a spine from the Carboniferous Limestone of Armagh, without observation.

In the “ British Paleeozoic Fossils,” p. 633, Prof. M‘Coy places two species, viz.:—
L. junceus and L. jenkinsoni in the genus Leptacanthus, observing that the genus
is a Carboniferous and Oolitic one.

Messrs. Newberry -and Worthen, in 1866, described a spine which was doubtfully
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 347

referred to the genus Leptacanthus, viz., L. occidentalis, with the remark that there
seems “little probability that they are generically identical with those from the
Oolite.” The general form is similar, but the striated or obscure and confusedly costate
surface of the typical Leptacanthi must have given them an aspect widely different
from that of these spines so uniformly and regularly ribbed throughout. He
further points out, that in no instance have teeth becn found in the Jurassic and
Carboniferous rocks, which are common to both and might have belonged to the
fish bearing the spines Leptacanthus. The close resemblance of these spines with
the slender and compressed forms which have been included in Ctenacanthus, such
as C. distans, M‘Coy, and C. gracillimus, N. and W., is also remarked, and a sugges-
tion made that these slender and flattened species of Ctenacanthus and the Carbon-
iferous Leptacanthus should be combined to form a new genus separate alike
from Ctenacanthus and Leptacanthus.

This suggestion was to some extent carried out by Messrs. Orestes St. John and
A. H. Worthen, in the sixth volume of the “Geol. Survey of Illinois,” p. 432, by the
formation of the genus Acondylacanthus, with two species from the Kinderhook
fish-bed and the Keokuk limestone respectively, viz.—A. gracilis and A. equi-
costatus. This genus is also considered to embrace the following described species,
all of which pertain to the Carboniferous period: Leptacanthus junceus, M‘Coy,
L. jenkinsoni, M‘Coy, LZ. occidentalis, N. and W., and Cladodus tenuistriatus,
Romanowsky. The last named, though evidently a spine of Leptacanthus, was
considered by Col. Romanowsky to be associated specifically with the teeth of
Cladodus, from the fact that the two were found associated with each other.

The rearrangement as suggested by St. John and Worthen appears in every
sense preferable and will be followed in the present instance.

Acondylacanthus colei, Davis.
(Pl, Xi, fie.7 2, Bl yt fe)

Fin-spine, gently arched and gradually tapering toa fine point. Base imperfect ;
length preserved 5°5 inches, greatest diameter at base 35 inch, which steadily
diminishes towards the apex. Transverse section rounded anteriorly and laterally,
posterior flattened or depressed ; internal cavity, large and round. Sides orna-
mented with a number, about twelve, of delicate, enamelled costee, extending
longitudinally, parallel with the anterior surface, towards the base they increase by
bifurcation; the intermediate hollows are smooth and narrow. ‘The anterior
margin is rounded, the longitudinal strize of the sides are continued anteriorly ;
there is no median keel. Posterior face, broad, somewhat deeply channeled.
Latere-posterior angles sharply defined, bearing on each side a row of obtusely
pointed, widely separated denticles.

Tho spines comprised in this species have been classed with those of Acondyla-
''348 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

canthus distans, in the cabinets of Lord Enniskillen, but a comparison with the
figure of that spine given on Plate XLVL.,, fig. 5, will prove sufficiently conclusively,
that the two forms are quite distinct. A. colei bears a nearer resemblance to
A, equicostatus, St. John and Worthen (“Geol. Illinois,” Vol. VL, p. 634, pl. xvi., figs.
12, 13), but it differs from that species in its more robust aspect, in the roundness
of its section, and, so far as can be ascertained—for the posterior portion of the
spine is slightly crushed—in the greater width of the posterior groove.

I have taken the liberty to dedicate this species, which I regard as the type of
the genus amongst British species, to the Earl of Enniskillen, whose magnificent
collection forms the basis on which this memoir is built.

Formation and locality : Mountain Limestone, Armagh.
Lx coll. Earl of Enniskillen.

Acondylacanthus tuberculatus, Davis.
(PIA VA fier 4)

Spine, imperfect ; the point and base not present. Remaining portion 2°5 inches
in length, diameter nearest basal end ‘35 inch, gradually tapering to a point.
Spine when perfect probably four inches in length. It is slightly curved, more
so on the anterior than the posterior surface. Transverse section of spine is
triangularly elliptical, widest posteriorly, and somewhat accuminate anteriorly.
Lateral surfaces compressed, covered with smooth enameled costie, about twelve
in number near the basal extremity, and decreasing to five or six near the apex.
The intermediate hollows are half the diameter of the coste, deeper than wide.
The anterior surface is marked by a median keel, consisting of a similar ridge to
those on sides, but larger and slightly broader. The ridge is coated with glistening
enamel, produced to form a series of small tuberculose prominences, separated from
each other by about their own diameter ; near the apex of the spine these tubercles
become considerably smaller in size, more closely approximated, and somewhat
irregular in disposition. The posterior surface channeled in basal portion, the
cavity becoming enclosed, and continuing to within a short distance of the end.
Each latero-posterior angle is armed with a row of acutely pointed, round, re-
curved denticles, springing from a prominent and continuous ridge of ganoine
which extends along and forms the angle independently of the lateral costs. The
base not known.

The species most nearly related to this one appear to be Ctenacanthus (2)
burlingtonensis and C. keokuk, derived respectively from the limestones indicated
by their specific names at Iowa and Illinois, and described by Messrs. St. John and
Worthen in the “Palzeontology of Iinois” (Vol. VI., pp. 426, 427, pl. xv.,figs. 6, 7, 8).
The two approximate very closely in specific characters and, according to the
authors named, where a considerable series are together, it is not without difficulty
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 349:

and doubt that they can be separated. The Armagh specimen differs from the
American ones in being smaller, and somewhat shorter in proportion to its breadth.
Both the species named differ from A. tuberculatus, in possessing a much larger
number of lateral costee, and in the latero-posterior denticles being blunt and obtuse,
short, and more widely separated. The costz, also, nearest the anterior margin are
tuberculose, whilst those of the Armagh specimen are quite smooth and simple.

Formation and locality : Mountain Limestone of Armagh.
Ex coll. Earl of Enniskillen.

Acondylacanthus distans, M‘Coy.
(PL XDVE fie. 3)

Ctenacanthus distans—F. M‘Coy, 1848. “ Ann.and Mag. Nat. Hist.,” 2nd Ser., Vol. IT., p. 116.
- J. Morris, 1854. “Cat. Brit. Foss.,” p. 323.
e e F. J. Pictet, 1854. ‘ Traité de Paléont.,” Vol. II., p. 290.
: F. M'@oy, 1855. “Brit. Paleoz, Foss.,” p. 620, pl.-3 k, fig: 15.

Morris and Roberts, 1862. “ Quart. Journ. Geol. Soc.,” Vol. XVIIT., p. 100.

“Spine, compressed, gently arched, very long, slender, tapering at the rate of
only three lines in five inches; posterior face with two rows of numerous, small,
short, conical compressed teeth, slightly bent downwards, rather more than the
width of their base apart; sides flattened with about ten or twelve close, flattened,
longitudinal ridges of irregular width, the broadest occasionally subdividing as they
approach the base, all the ridges crenulated by small tubercles, about double the
thickness of the ridge from each other; those on the anterior ridges are transverse
and slightly oblique, while those nearer the concave margin are smaller, and
assume the appearance of lengthened nodulose swellings as in Physonemus.

“This is a remarkably long and slender ray; one specimen in the University
collection, of which a considerable portion of the apex must be lost, measures six
inches in length, and only six lines in width at the broadest part near the base,
the broken distal extremity being three lines wide, which would probable indicate
a further inch and a half of length. The portion of the base inserted in the flesh
is small and gradually tapering. I am not certain of the exact form of the
section,’ —(M‘Coy.)

This species is in every respect, except that the longitudinal ridges are crenulated
and not smooth, a good example of the genus Acondylacanthus. In the Enniskillen
collection, though there is a large number of specimens, there is not one with the
basal portion perfect, and it may be inferred that the Ctenacanthus type of base
with a wide, open, posterior sulcus did not exist ; if it had—and other examples of
that genus may be taken as guides—some of the specimens would have had the base
preserved. It rather appears probable that the opening was terminal, and that a
very small portion of the spine was embedded in the flesh. The two species named

 
''350 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

by St. John and Worthen, Ctenacanthus burlingtonensis and C. keokuk, should also
be removed to this genus.

This species differs from A. tenuistriatus, Davis, in having fewer and broader
longitudinal ridges, and in the surface of the ridges being more boldly crenulated.

Formation and locality : Mountain Limestone, Armagh.
Ex coll. Ear) of Enniskillen.

Acondylacanthus tenuistriatus, Davis.
(EE AY, fic. 8.)

Spine, imperfect at both ends, five inches in length, ‘45 inch wide at basal end,
from which it gradually diminishes to °3 inch at the opposite one. Transverse
section sub-triangular, sides much compressed and slightly rounded, anteriorly
forming an acute angle, iatero-posterior angles sharp, base slightly concave, internal
pulp cavity sublenticular in section, probably terminal at the base, without open
basal cavity. The spine is gently and uniformly arched posteriorly. The sides
are covered with about twenty smooth, enameled ridges occasionally slightly beaded
by excrescences, separated by equidistant intermediate sulci. The anterior margin
is trenchant, formed of an enameled keel, in some parts of its length presenting a
slightly serrated appearance. Latero-posterior angles rounded and prominent,
armed with a double row of small recurved denticles broadly implanted, acutely
pointed, separated by about twice their own diameter near the distal extremity,
closer towards the base, posterior surface channeled. Base not preserved.

It isaremarkable feature in the specimens composing the genus Acondylacanthus
that the basal extremity has not been preserved. ‘There is in every instance where
the spines have been described, both American and British, the laconic intimation
that the base is unknown.

As already observed this species differs from A. distans in the tenuity of its
longitudinal ridges and the much finer tuberculation of their surface. It is also a
longer spine in proportion to its breadth, and more curved, than Acondylacantius

distans.
Formation and locality: Mountain Limestone, Armagh.
Ex coll. Ear] of Enniskillen.

Acondylacanthus junceus, M‘Coy.
(Plo SEV 1 fe 635

Leptacanthus junceus—F. M‘Coy, 1848. “ Ann.and Mag. Nat. Hist.,” 2nd ser., Vol. II.,p.122.
) s J. Morris, 1854. “Catal. Brit. Foss.,” p. 332.
53 2 F, J. Pictet, 1854. ‘Traité de Paléont.,” Vol. IT., p. 288.
e ‘5 F. Moy, 1855. ‘Brit. Paleoz. Foss.,” p. 633,.pl. 3 G, fig. 13.
- 35 Morris and Roberts, 1862. ‘Quart. Journ. Geol. Soc.,” Vol. XVIIL, p. 101.
. 2 prrosirong, Young.) 1876. ‘Catal. West. Scot. Foss.,” p. 62.

and Robertson, f
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 351

The specimen described by Prof. M‘Coy, as Leptacanthus junceus, consists of a
small fragment of a spine from the black beds of shale, above the Mountain Lime-
stone of Derbyshire. It appears to be unique, and is in the collection at the Wood-
wardian Museum, Cambridge. The following is Prof. M‘Coy’s description of it :—
“Nearly straight, about one and a half lines wide; section semi-elliptical ; sides
gently convex, meeting in front to form a sharp anterior edge, and converging behind
to a narrow posterior sulcus, bordered on each side by a row of strong conical down-
ward-curved teeth, little longer than wide, and about the width of their bases apart ;
each side with about seven longitudinal, narrow, equal, thread-like ridges, twice
their diameter apart, and having between each pair two or three obsolete longitu-
dinal striz.” This is included in Leptacanthus rather than in Homacanthus, from the

great number and regular delicacy of the ridges.
Formation and locality : Black Shale above Limestone, Derbyshire.
Kx coll. Woodwardian Museum, Cambridge.

Acondylacanthus jenkinsoni, M‘Coy.

(Pi REEVE, Bes 2, 22)

Leptacanthus jenkinsoni—F. M‘Coy, 1855. “Brit. Paleoz. Foss.,” p. 633, pl. 3 G, figs. 14-16.
Morrisand Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. XVIIL, p. 101.
Young and Armstrong, 1871. ‘“Trans.Geol. Soc.,Glasgow,” Vol. IIL., supt., p.72.

9 9

29 9

‘ Armstrong, Young, ip OE +
? ” gah ecctaon. 1876. “Catal. West. Scot. Foss.,” p. 62.

“ Fin ray, very long, slender, tapering at the rate of one line in two inches, very
much compressed ; sides flattened ; anterior face surmounted by a strong keel.
Sides with about 14-16 ridges, averaging six in two lines; about twenty ridges
when six lines wide, and about ten, when two lines wide, (in the latter case near
the apex, a smooth band runs along the posterior edge), separated by narrow,
shallow sulci; ridges often inconspicuous, and singly interrupted or discontinued
at irregular distances; both the ridges and sulci obscured by a longitudinal,
slightly irregular striation, posterior edges set with very numerous and very small
much-hooked denticles, nearly twice the width of their bases apart, three in three
lines, at four lines wide. Length unknown, but upwards of five inches ; greatest
observed width six lines, at which the thickness is only two lines.’— (M‘Coy.)

Transverse section, the sides are straight, bending over anteriorly, and joining to
form a median acutely-pointed carina ; posteriorly a shallow sulcus, is bounded by
acute latero-posterior angles with denticles. Internal cavity large, sub-lenticular,
laterally and anteriorly conforming to the shape of the outer surface, posteriorly
produced in the centre, and approaching near to the surface of the posterior sulcus ;
base, if any, unknown.

The specimens figured by Prof. M‘Coy are in the collection at the Woodwardian
Museum, Cambridge, and, together with the one now given (Pl. XLVL., fig. 2), form
the entire number of specimens known.

TRANS. ROY. DUB. SOC., N.S., VOL. I. 38M
''352 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

This species bears a near resemblance to A. gracilis (St. J. and W.) ; its principal
points of difference lie in the more angular form presented in transverse section,
and the form of the internal cavity ; the posterior denticles are smaller, less frequent,
and not so acutely pointed.

Formation and locality : Mountain Limestone, Lowich, Northumberland.
Ex coll. Woodwardian Museum, Cainbridge.

Acondylacanthus attenuatus, Davis.
Cy Ip ie 3.)

Spine, much compressed, gracefully arched backwards, three inches in length,
base imperfect, lowest portion °3 inch wide, gradually tapering towards the opposite
extremity, and ending in a fine point. Anterior surface, with a prominent longitu-
dinal keel, lateral surfaces with 12-14 longitudinal ridges, wider than the inter-
mediate sulci; broad and flat at top, smooth ; towards the base the number of ridges
increases by bifurcation, A slightly deeper and wider sulcus than the other, passes
between the last posterior ridge and the latero-posterior angle. The angle is
slightly rounded, and armed with a row of broadly implanted, recurved, sharply-
pointed denticles, separated from each other by about their own diameter.
Posterior surface hidden by the matrix. Transverse section at part preserved
nearest the base, is two and a half times greater in diameter between the antero-
posterior margins than between the lateral ones ; lateral surfaces converge anteriorly
and form an acuminate apex ; posteriorly the surface curves inwards, forming on
the surface a longitudinal median sulcus, with a row of denticles on each side.
Internal cavity, small, oval, placed near the posterior margin, and extending not
more than half the diameter of the spine towards the opposite one.

This beautiful specimen appears to be unique. It was presented by the Rev. W.
Stokes, with several others, to the Woodwardian Museum, at’ Cambridge. It
presents a more graceful appearance than A. jenkinsoni, to which it bears some
resemblance, but may be distinguished from it by the comparatively large size of
the posterior denticles, and the form of its transverse section and internal cavity.

From A. colei, to which it also bears an outward resemblance, it is separated by
the roundness and robustness of the spine of A. colei, compared with the ovally
lenticular, and compressed sides of A. attenuatus.

This species offers several points of resemblance with the spine, Acondylacanthus
(Leptacanthus) occidentalis, figured by Newberry and Worthen (Geol. Illinois,”
Vol. IL, p. 116, pl. xii., fig. 2.) but appears to be sufficiently distinguished by the
somewhat shallow posterior sulcus, and roundness and robustness of its denticles,
those of A. occidentalis being conspicuously furrowed, bordered by two rows of
compressed and depressed hooks. |

Formation and locality : Carboniferous Limestone, Armagh.
Ex coll, Woodwardian Museum, Cambridge.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 353

Genus—Asteroptychius, Agass, MS.

Asteroptychius—L. Agassiz, 1833. “ Poiss. Foss.,” Vol. IIL, p. 176, indet.
F. M‘Qoy, 1854. “ Brit. Palzeoz. Foss.,” p. 615.

2)

“ Bony fin ray, compressed, long, slender, gradually tapering to a point at the

distal end, and abruptly tapering at the striated proximate end, or base of insertion;
sides moderately convex, converging to the anterior edge, which is strongly
keeled ; posterior face with a moderate cavity, each lateral edge having a row of
small teeth, directed upwards. Surface of the sides with several smooth, thread-
like ridges, separated by broader, flat, longitudinally striated spaces, on which are
regularly scattered smooth, spinous tubercles ”—(M‘Coy.)

The spines constituting this genus were named by Prof. Agassiz, but were not
described. The above description is taken from Prof. M‘Coy’s “ Brit. Palzeoz. Fossils,”
page 615. It is necessary to state, in addition to the above, that the internal cavity
is terminal at the base, and not posteriorly open, as in the spines of Hybodonts
generally. Several species of Asteroptychius have been described by American
paleontologists and in each case the base is unknown; perhaps this may be explained
by the fact of the cavity being terminal, and the portion implanted in the body of

the fish comparatively short.

Asteroptychius ornatus, Agass.

(Pl. XLVI, figs. 7-9.)

Asteroptychius ornatus—L, Agassiz, 1837. ‘“ Rech. sur les Poiss. Foss.,” Vol. III.,p. 176, indet.
. : J. E. Portlock, 1843. “Rept. Geol. Londonderry, &ec.,” p. 461.
o C. G. Giebel, 1848. “Fauna der Vorwelt,” Vol. L, pt. 3, p- 310.
3 is H. G. Bronn, 1848. “ Nomencl. Paleont.,” p. 123.
os 5 1849, “Enumerator Paleont.,” p. 653.
»  semiornatus—F. M‘Coy, 1848. “ Ann. & Mag. Nat. Hist.,” 2nd ser., Vol. IL., p. 118.
»  ornatus— J. Morris, 1854. “Catal. Brit. Foss.,” p. 318.
»  sSemiornatus— x 1854, + He Dp. oS
» ornatus—  F., J, Pictet, 1854. “Traité de Paléont.,” Vol. IL., p. 291.
»» Semiornatus— oS 1854. - . VOT i oon:
» ornatus— FF, M‘Coy, © - 1855. “Brit. Paleoz. Foss.,” p. 615, pl. 3 K, figs. 23, 24,
»  Semiornatus — % 1855. 7 4g S p- 616, pl. 3 K, fig. 22.
»  ornatus— Morris & Roberts, 1862. “Quart. Jour. Geol. Soc,” Vol. XVIIL., p. 99.
yy semiornatus— «5 is 1862. a a if - Vol, ZVI, 9.99.
» ornatus— J.J. Bigsby, 1878. ‘Thesaurus Dev.-Carb.,” p. 347.
semiornatus— ss 1878. a fe . an Peete.

Qpines, long, tapering, slightly curved, length varying from two to five inches.
Specimen 4°5 inches in length, ‘4 inch in breadth near the base, tapers gradually
and gently upwards to an acute point. Base slightly contracted in width, with
finely striated surface, Transverse section triangular, two sides formed by the
lateral surfaces which meet anteriorly with an acute angle, posterior surface, one-
half the length of each anterior one, forms the base. Internal cavity, medium size,

conforming generally in form to that of the outer walls, extends almost to the
3M 2
''354 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

apex of the spine ; basally, it forms a terminal opening as in the Pleuracanths. <A
well-defined carina of smooth ganoine extends along the anterior surface of the
spine ; the sides are ornamented by a variable number of narrow, smooth, longitu-
dinal ridges, which towards the base increase by bifurcation. The ridges are
separated by wide flat spaces, along which extend a number of minute longitudinal
striee, and in some of the spaces there is also a row of widely-separated, irregular,
smoothly-rounded prominent tubercles, generally restricted to the spaces on the
anterior portion of the spine, and occasionally restricted to the space on each side
the anterior ridge. The posterior surface is depressed or hollowed, slightly
pustulate, with a well developed median ridge. The postero-lateral angles are
acute, with a row on each of small acuminate denticles, the points of which are
directed upwards.

Paucity of specimens probably led Prof. M‘Coy to believe that the form with
a single row of tubercles on each side the anterior carina was of sufficient import
to render necessary the institution of a separate species. A large series of
specimens, however, proves that this is not so, every variety of tuberculation may
be traced, and seems to be merely accidental. Specimens are not uncommon in
which the several spaces have rows of tubercles, which for this reason would be
classed with Asteroptychius ornatus, and at the same time have seven or eight,
and near the base almost double that number of ridges. All the characters of A.
semiornatus may be found combined indiscriminately with those of A. ornatus, and
for this reason they are both here included in the latter, which has priority.

Several species of Asteroptychius have been found in the limestone of Burlington,
Keokuk, St. Louis, &c., in Illinois, America.

Formation and locality : Mountain Limestone, Armagh.
Ez colt. Earl of Enniskillen.

Genus.—Compsacanthus, Newberry.
Compsacanthus, Newberry, J. S., “Geol. Survey, Ohio,” Vol. I, p. 331.

““Spines, of small size, gently curved backwards ; exposed portion smooth and
polished ; section at all points circular; a single row of relatively large, remote,
depressed hooks set along the posterior median line.”~—(Newberry.)

Compsacanthus carinatus, Davis.
(Fl, XLVI. fe. 10.)

Spine, slightly curved, posteriorly imperfect, basal and apical terminations wanting.
Portion preserved is 4°3 inches in length, antero-posterior diameter ‘65 inch at
the part nearest the base and ‘4 inch at the opposite end, where the lateral diameter
is ‘°22 inch. In transverse section the spine is elliptical ; an internal cavity extends
from the base upwards to a short distance from the apex, the basal opening is
terminal and wide ; the walls of the spine at that portion are thin, and consequently
somewhat crushed and fractured ; towards the apex the walls are much thicker, and
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 355

the internal orifice reduced in diameter. The base was probably short, partaking
generally of the character of that of the Pleuracanths. The lateral surfaces are
convex and covered uniformly with longitudinal striz. Anterior surface slightly
curved longitudinally: it is produced along the median line so as to form a
prominent keel, which extends the whole length of the spine ; on each side of the
keel there is a deep and broad groove, connecting it with each lateral surface.
Posterior surface armed with a single row of recurved, pointed denticles extending
the whole length of surface preserved. The denticles are large, broad at the base,
tapering rapidly to the point, curved towards the base of the spine.

The genus Compsacanthus was instituted by Dr. Newberry to comprise spines
easily distinguished from all others by having a single row of large hooks along
the posterior median line. The specimen serving as the type for Dr. Newberry’s
description was externally smooth and slender, and circular in section. In addition
to Newberry’s species, two species have been described by the writer, from the
cannel coal of the West Riding of Yorkshire (‘‘Quart. Jour. Geol. Soc.,” Feb., 1880,
p. 62). One of the Yorkshire species is triangular in section the other much com-
pressed laterally: they have in each case a single row of denticles along the
posterior surface. In the latter respect all the species agree ; but in order that the
genus Compsacanthus may embrace all the species so far described it will require
some modification of the original description. It may be as well, however, for the
present to allow it to remain unchanged ; there is the possibility that further dis-
coveries and investigation may show the necessity of new genera for some of the
forms of spines with only a single median row of denticles. The species described
above rests on a unique example in the Enniskillen collection, which certainly
differs very greatly from the type species of the genus, and it is with considerable
hesitation that it has been included in the genus.

Formation and locality: Mountain Limestone, Armagh.
Ex coll. Ear] of Enniskillen.

Genus.—Cosmacanthus, Agass.
Cosmacanthus, Agassiz, “‘ Poiss. Foss. vieux grés rouge,” p. 120.

“Small spines, feebly arched, or almost straight ; entire surface ornamented by
tubercles disposed in regular, longitudinal series ; the most distinct are near the
anterior margin of the spine, becoming gradually feebler towards the posterior
margin, where they tend to disappear.”

Only one species was known to Professor Agassiz from the Old Red Sandstone
of Elgin. It was named Cosmacanthus malcolmsoni.

Cosmacanthus marginalis, Davis.
(PL XLVIIL, fig. 3.)

Spine, 2:7 inches in length, basal and apical extremity each imperfect, greatest
diameter near base *35 of an inch, gradually tapers to 2 at the part preserved
''356 On the Fossil Fishes of the Carboniferous Limestone Serves of Great Britain.

nearest the point; straight: transverse section somewhat triangular, diameter
from anterior to posterior surface rather greater than that between the postero-
lateral angles. Anterior surface rounded; lateral surfaces slightly depressed,
especially towards the postero-lateral angles. The whole of the anterior and
lateral surfaces are strongly tuberculated, the tubercles arranged diagonally in
parallel rows across the spine ; they are large along the front and for two-thirds
of the breadth of the sides, the remaining third nearest the back of the spine on
each side is covered with minute tubercles without definite arrangement. The
larger tubercles are slightly elevated on a bony pedestal, the upper surface thickly
coated with ganoine. A deep circular groove extends along the posterior surface.
The junction of the posterior and the lateral surfaces is produced to form a broadly
rounded angle coated thickly with ganoine, slightly raised here and there into
minute tubercles. ;

This species differs from Cosmacanthus maleolmsoni, Ag., from the Devonian rocks
(‘‘ Poiss, Foss. du vieux grés rouge,” tab. 33, fig. 28), in the presence of the thick
rounded mass of ganoine which invests each of the latero-posterior angles. From
Cosmacanthus carbonarius, M‘Coy (“ Ann. Mag. Nat. Hist.,” Second Series, Vol. IT.,
p- 119), described as having the posterior sulcus very wide and rounded “ being
bounded by the last lateral row of tubercles on each side. A fragment 1 inch
8 lines long and 24 lines wide at the narrow end, increases at the rate of nearly
2 lines in an inch.” This species is distinguished also by the presence of the posterior
margin of ganoine, by the shallow posterior sulcus, and its very slight decrease in
diameter from the base upwards.

Except that there are no denticulations along the postero-lateral angles, this genus
appears to bear a close relationship to that of Lepracanthus (Ag.) from the Coal
Measures.

Formation and Locality ; Carboniferous Limestone, Armagh.
Ex coll. Enniskillen,

Cosmacanthus carinatus, Davis.
(Pl, XLV ILL, fig. 4.)

Fin-spine, very slightly curved along anterior margin, posterior straight,
1°5 inches in length, 15 in greatest breadth at the junction of the base and exposed
part. Base tapering. Exposed part ensiform, ending in an acute point. In
transverse section the spine is an obtuse-angled triangle, the diameter of the
posterior portion being greater than from back to front. The lateral surfaces are
thickly covered with ganoine-coated tubercles. The tubercles when magnified
present a most peculiar appearance : rising on a stem from the surface of the spine
to one and a half times their diameter, they become spread out or extended towards
the base of the spine ; the surface of the tubercle in this direction is denticulated in
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 357

a variety of forms, not unfrequently presenting the appearance ot a hand with
extended fingers. The tubercles are not more than one-fiftieth of an inch
in diameter, and are devoid of arrangement. The anterior surface is angular
and produced in the form of a keel, thickly coated for the most part with bright
glistening ganoine. Near the base line the anterior keel is broken into two or
three separate tubereles which bear much of the character of those on the sides of
the spine, further up the spine the tubercles coalesce and the ganoine extends to
the point in constantly increasing thickness and breadth, so that on reaching the
apex the ganoine is equal to the whole diameter of the spine, ending in a bluntly
rounded point. The posterior surface is deeply channelled by a pulp cavity,
extending considerably beyond the basal portion towards the apex. The postero-
lateral angles are sharply defined but are devoid of denticles or hooks,

This spine differs materially from the preceding species, to which it bears a
superficial resemblance, in the character of its posterior cavity, in the possession
of a strong anterior keel of ganoine, and in the tubercles which ornament its sides.

Locality : Carboniferous Limestone, Armagh.
Ex coll. Earl of Enniskillen.

Cosmacanthus carbonarius, M‘Coy.

Cosmacanthus carbonarius—F. M‘Coy, 1848. “Ann. and Mag. Nat. Hist.,” 2nd ser., Vol.
EL. 9. 149,
5 . J. Morris, 1854. “Catal. Brit. Foss.,” p. 323,
5 F. J. Pictet, 1854. “Traité de Paléont.,” Vol. IL, p. 287.
4 a Morris & Roberts, 1862. “ Quart.Jour.Geol. Soc.,” Vol. X VIIL »p- 100.
‘s 5 J. J. Bigsby, © 1878. “Thes. Devon.-Carb.,” p 351.

“Spine, nearly straight, semicylindrical ; section semilunate ; sides and anterior
face broadly rounded in one continuous curve, posterior sulcus very wide, rounded ;
about eight longitudinal rows of small oval tubercles on each side, the tubercles
nearly touching in each row, and the rows less than their diameter apart ; no
posterior teeth, the posterior sulcus being bounded by the last lateral row of
tubercles on each side. A fragment, 1 inch 8 lines long and 2} lines wide at the
narrow end, increases at the rate of nearly two lines in an inch.”—(M' ‘Coy.)

Professor M‘Coy remarks that this species differs from the Devonian C. maleolm-
son, Ag., in its greater size and much more numerous rows of tubercles. Two
imperfect specimens were in the collection of Captain Jones, from Armagh. The
specimens from which the above description was written have either become mis-
placed or lost : they do not appear to be amongst the types which have been preserved
from the collection of the late Admiral Jones.
''358 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

Cosmacanthus priscus, Agass.

(Pl. XLVIIL,, fig. 1, 2.)

Leptacanthus priscus—L. Agassiz, 1837. ‘Rech. sur les Poiss. Foss.,” Vol. III.,p. 176, indet.

a s J. E. Portlock, 1843. “Geol. Rept. Londonderry, &c.,” p. 461.

5 a C. G. Giebel, 1848. “Fauna der Vorwelt,” Vol. L., pt. 3, p. 306.

: ss H. G. Bronn, 1848. “‘Nomencl. Paleont.,” p. 634.

Nemacanthus priscus—F. M‘Coy, 1848. “Ann.& Mag. Nat. Hist.” 2nd ser., Vol. IL, p. 120.
Leptacanthus priscus—J. Morris, 1854. “Catal. Brit. Foss.,” p. 332.

Nemacanthus priscus—- ee 1854. - s p. 334.

Nemacanthus priscus—F. J. Pictet, 1854. “Traité de Paléont,” Vol. IT., p. 286.
Leptacanthus priscus— oy 1854. a 3 % Vol. IL, p288:

Ae " Morris & Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. XVIITI., p. 101.
Nemacanthus priscus— - . 1862. is % a Vol. XVIIL,-p. 101,
Leptacanthus priscus—J. J. Bigsby, 1878. “Thesaurus Devon.-Carb.,” p. 359.

Nemacanthus priscus— . 1878. e s . p. 359.

Spine, slightly curved, nearly four inches in length, basal end complete, distal
one broken off. It is also split in two along the middle, giving a longitudinal
section and exposing the internal canal, which is round and rather more than one-
third the diameter of the spine. Towards the base the canal gradually increases
in size, the walls becoming thinner near the extremity. The base, one inch in length,
is separated from the exposed part of the spine by a diagonal line extending from
the anterior margin upwards to the posterior one. The contact of the two sides at
an acute angle forms an enamelled keel which extends along the anterior
margin. The sides are covered by numerous tubercles without definite
arrangement, the intermediate spaces are covered with a reticulated network of
minute punctures and lines.

Spines of the genus Nemacanthus occur in the Liassic formations and bear a
superficial resemblance to that of Cosmacanthus. Nemacanthus is, however, com-
pressed and oval in section, and only a portion of the lateral surface is covered by
tubercles ; whilst in Cosmacanthus the section is triangular, with an inclination
to roundness. The pulp-cavity is enclosed to a larger extent by the base of the
spine, and the surface is almost uniformly covered by tubercles. The posterior
margins in Nemacanthus are denticulated, whilst in the genus under consideration
there are no denticles.

The species may be distinguished by the round depressed form of the tubercles and
the reticulated series of punctures which occupy the spaces intermediate between
them, and in the indefinite manner in which the tubercles are arranged on the surface.

Leptacanthus priscus was not described by M. Agassiz, and the genus as
defined by Prof. M‘Coy (Brit. Palzoz. Fors., p. 633) is quite different to the defini-
tion here given of Cosmacanthus priscus.

Formation and locality : Carboniferous Limestone, Armagh.
Ex coll. Geological Society, London.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 359

Genus. —-Lispacanthus, Davis.

Spine, medium size, ovate in section, laterally compressed, gradually tapering
to a point. Surface entirely smooth. Pulp cavity internal. Base wide, open
terminally, walls thin, divided from exposed surface by a very oblique line.

Lispacanthus retrogradus, Davis.
(Pl; SLVIEE, fe. 5;)

Spine, from the base upwards the spine is considerably curved posteriorly, and
near the apex slightly recurved towards the anterior aspect. It is nearly four
inches in length, and its greatest diameter at the base 4 of an inch. The breadth
is gradually reduced towards the apical extremity and ends in a fine point. The
line dividing the exposed part of the spine from that imbedded in the body of the
fish extends diagonally across the spine in an extremely oblique direction and
indicates that the spine extended at a very small angle of elevation along the body
of the fish, and in all probability was never raised more than a few degrees. The
whole surface of the spine is smooth; anteriorly it is broad, rounded, with a shehtly
acuminate ridge along the median line. The sides are depressed, having the appear-
ance of a wide and shallow groove extending from the junction of the anterior
portion of the exposed part with the base, to within half an inch of the point. The
posterior surface possesses a very slight indication of a groove, and leads to the
impression that the spine was not connected with a fin. The base is imperfect ; it
is fibrous and was firmly implanted.

This spine offers several peculiarities which appear to indicate that its relation-
ship was not with the ordinary types. Its connexion with the body of the fish as
indicated by the base line, and the absence of a posterior groove for the attachment
or accommodation of a fin shows that it was free and possibly only used for offensive
or defensive purposes; these characters remove it from the Ctenacanthoid type
The base also differs from the Pleuracanth or Chimeroid types, its oblique implanta-
tion and wide aperture are quite distinct from the tapering base and almost
vertical position of those genera.

Formation and locality: Mountain Limestone, Armagh.
Lx coll. Earl of Enniskillen.

Lispacanthus gracilis, Davis.
(PL XLVUL" fig: 6.)

Spine, long and tapering, acuminate, gently curved, length five inches, greatest
breadth at base *4 inch, gradually and evenly contracts in diameter to the apex, which
is sharply pointed. Transverse section circular, the internal cavity is terminal.
Surface of spine is smooth, a very slightly projecting keel extends along the anterior

surface. The posterior surface is devoid of denticles, and so far as can be seen of
TRANS. ROY. DUB. $0C..NS..VOL. 1 : 3N
''360 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

any sulcus or groove. The portion of base implanted in the body of the fish was
small, being ‘65 of an inch, equal to about one-eighth the entire length of the spine.

This unique specimen was collected by the late Sir Roderick Murchison, and
placed in the Geological Society's museum. Its closest relationship appears to be
with Acondylacanthus, N. and W., and Lispacanthus, Davis. It differs from the
former in having no surface ornamentation or posterior denticles, though its general
contour is similar; and from the latter ia the more evenly circular form of the base
and spine generally, and also in the absence of the deflexure characteristic of
Inspacanthus retrogradus.

I propose for the present to place the specimen in the genus Lispacanthus ; though
not agreeing in all particulars with the characters of that genus, it appears prefer-
able to include it rather than institute a new genus for its especial occupation.

Formation and locality : Mountain Limestone, Kendal Fells, Westmoreland.
Ex coll. Geological Society, London.

Genus.—Dipriacanthus, M‘Coy.
Dipriacanthus—M ‘Coy, “ Brit. Palzoz. Foss.,” p. 627. :

‘Spine, small, arched, tapering, much compressed, minutely and irregularly
tuberculated ; two rows of small conical teeth on the posterior margin, and two
rows of larger adpressed teeth on the anterior face directed upwards.’ —(M‘Coy).

Prof, M‘Coy in the “ Annals and Magazine of Nat. Hist.,” described two species
of Dipriacanthus, viz:—D. Stokesii and D. falcatus. The only specimen which I have
seen of the latter is in the museum of the Geological Society, London. The name

attached is in the handwriting of Prof. M‘Coy, so that this specimen is probably |

the one described. It is about one inch in length and possessed of denticles on the
posterior margins, but I fail to find any trace of denticulation on the anterior one.
As this specimen does not possess the characters distinguishing the genus as de-
fined by M‘Coy, it will not be included in the genus. Dipriacanthus stokesiv is an
altogether different specimen with a peculiarly expanded base which does not con-
form to any ordinary forms. It resembles to some extent the shorter branch of
Cladacanthus, but with the present limited knowledge of the form, being restricted
to a single specimen, it may not be advisable to remove it.

_Dipriacanthus stokesii, M‘Coy.
(Pl, XLVIUIL; fig. 10.)

Dipriacanthus stokesii—F, M‘Coy, 1848. “Ann.and Mag. Nat. Hist.,” 2nd ser., Vol. IT.,p. 121,
5 ss J. Morris, 1854. “Catal. Brit. Foss.,” p. 325.
. FE. J. Pictet, 1854. ‘“Traité de Paléont.,” Vol. IL, p. 292.
> a F, M‘Coy, 1855. ‘Brit. Paleoz. Foss.,” p. 627, pl. 3 K, fig. 18.
i sf Morris & Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. XVIII, p. 100.

5, 3 J. J. Bigsby, 1878; “Thesaurus Devon.-Carb.,” p. 355.

 

 
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 361

“Spine, slightly arched, much compressed, sides flat, anterior and posterior
margins narrow, obtusely rounded ; section oblong, the long diameter being four to
five times longer than the short ; teeth of the posterior margin slender, conical, pro-
Jecting at right angles to the spine ; teeth of the anterior margin large, thick, smooth,
the upper sharp edge widest, closely adpressed to the surface; surface closely
covered with small irregular smooth granules, which under a strong lens are found
to be radiatingly striated at their base, and with the intervening narrow spaces very
minutely granulated.

“When highly magnified the granulation of this spine resembles on a small scale
the star-like style of ornament of the bony plates of Asterolepis (Eich). The base
is imperfect, but apparently dilated in a remarkable degree, and in its present state
the lower portion seems bent at a considerable angle from the curve of the rest of
the spine”

Formation and locality : Mountain Limestone, Armagh.

Lx coll. Woodwardian Museum, Cambridge.

Genus.—Homacanthus, Agass.
Homacanthus—Agass, “ Poiss. Foss. Vieux Gres Rouge,” p. 113.

M‘Coy, “ Brit. Paleoz. Foss.,” p. 632.

99

‘Fin-spine, small, rather rapidly tapering, moderately arched backwards ; sides
flattened, converging to the anterior face, which is obtusely keeled ; sides covered
with few very coarse, longitudinal ridges, and fine strize in same direction ; post-
erlor margin with two rows of denticles arched downwards ”—(M‘Coy). Base com-
paratively large, with external cavity open posteriorly.

Homacanthus microdus, M‘Coy,
(Pl. XLVIIL., figs. 7-9.)

Homacanthus microdus—F. M‘Coy, 1848. “Ann. & Mag. Nat. Hist.,” 2nd ser., Vol. IT.,p.115.
54 ee J. Morris, 1854. “Catal. Brit. Foss.” p. 329,
55 . F. J. Pictet, 1854, “ Traité de Paléont.,” Vol. II., p. 288.
= o F. M‘Coy, 1855, ‘ Brit. Paleeoz, Foss.,” p. 633, pl. 3 K, fig. 19,
A a Morris & Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. XVIIL, p. 101.
: " ay ome 1872, “Catal, West, Scot. Foss.,” p. 62.
9 ie J. J. Bigsby, 1878, “Thesaurus Devon.-Carb.,” p. 357.

Spine, slender, arched posteriorly, length 2°0 inches, the base occupying one-fourth
the entire length. Breadth at junction of base and exposed surface ‘2 of an inch,
thence it gradually tapers toa fine point, base slightly attenuated. Transverse
section triangular. Lateral surface with two or three longitudinal ridges, enameled
and broad. Intermediate hollows wide and deep, flat at the bottom with, in some
instances, a second series of minute longitudinal strie. Anterior margin formed by

a broad enameled keel extending from the base to the apex. Vosterior surface
3 N2
''362 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

hollow, basal portion forming a deep sulcus from which an internal cavity extends
upwards towards the superior extremity. Each latero-posterior angle is armed
with a row of recurved broadly-implanted, rapidly-tapering, finely-pointed teeth
rather widely separated, especially on that portion nearest the basal sulcus.

A second specimen, representative of others, is almost straight, shorter, and
wider in proportion to its length than those just described. In other respects it is
very similar. It possibly occupied a position in front of the second dorsal fin,
whilst the longer and more curved specimens may have been similarly placed before
the first dorsal fin, as in the existing Acanthias.

The description of Homacanthus given by Prof. M‘Coy was from a very imperfect
but at the time unique specimen. There is in the Enniskillen collection a consider
able series, which has led to modifications of, and additions to, the description given
by Professor M‘Coy.

Formation and locality : Mountain Limestone, Armagh.
Ex coll. Earl of Enniskillen.

Homacanthus macrodus, M‘Coy.

(PL XUN TUG fig 140)

Homacanthus macrodus—F. M‘Coy, 1848. “Ann. & Mag. Nat. Hist.,” 2nd ser., Vol. IT., p. 115.
ie 3 J. Morris, 1854. “Catal. Brit. Foss.,” p. 329.
5 os F. J. Pictet, 1854. “Traité de Paléont.,” Vol. IL, p. 288.
5 5 F. M‘Coy, 1855. “Brit. Paleoz. Foss.,” p. 632, pl. 3 K, fig. 20.
a 3 Morris & Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. XVIIL., p. 100.
ah x J. J. Bigsby, 1878. “Thesaurus Devon.-Carb.,” p. 357.

“ Spine, about eight lines long and two lines wide at the base, slightly arched and
tapering to a point, section compressed, trigonal, anterior face formed by a narrow
rounded keel ; posterior concave face bounded on each side by a large rounded ridge,
between which and the anterior keel there is on each side a still smaller rounded
longitudinal ridge ; the two posterior ridges on each side dichotomize near the
base of the two intervening spaces, the anterior is rather wider and the posterior
rather narrower than the ridges, which they separate; they are concave and very
finely striated longitudinally ; posterior face with twelve or fourteen very large com-
pressed falcate teeth, alternating in two rows, the alternating bases touching, keeled on
their convex edge, their length nearly equalling thewidth of the side of the ray at their
base.”

This spine is distinguished from the last, H. microdus, M‘Coy, by the absence of
striee in the sulci between the ridges, in the different arrangement of the longi-
tudinal ridges, and the large falcate teeth which extend along the posterior angles.
Thelatter characteristic and the lessnumerous ridges, distinguish it from H. arcwatus

Ag., of the Old Red Sandstone.

Formation and locality: Mountain Limestone, Armagh.
Ex coll. Woodwardian Museum, Cambridge.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 363

Genus.—Gnathacanthus, Davis.

Spine, triangular in section, long, and tapering. Lateral surfaces compressed
with five or six longitudinal ridges, sometimes with intermediate rows of smooth,
enameled tubercles. Anterior margin formed by the conjunction of the two lateral
surfaces, forming an acute angle, armed with widely spaced denticles one-third the
diameter of the spine in length, apex of denticles sculptured. Between the larger
denticles are several smaller ones possessing similar characters. Posterior surfaces
concave, wide, smooth or finely punctate with a slight median ridge, Postero-
lateral angles sharp and well-defined, minutely and closely tuberculated. Internal
pulp cavity large, conforming roughly to the external configuration of the spine.

This spine bears a somewhat close resemblance to those of the genus Gampsa-
canthus, St. J. and W. (“Palzeon. of IIl.,” Vol. VI., p.471), and especially to the species
G. typus of the same authors (op. cit. p. 472, pl. xxii, fig. 12). It differs mainly,
and to all appearance essentially in the charactet of the posterior surface and the
angular junction of the postero-lateral surfaces. In Gampsacanthus the posterior
surface is occupied by large, laterally compressed, subtrenchant denticles, slightly
curved downwards, widely spaced, and of nearly uniform size. The lateral surface of
the spine curves gradually to the base of these denticles. In the Armagh specimens,
on the contrary, the postero-lateral angles are sharp and form ridges along which
there are minute tubercles, whilst the posterior surface is broad, concave and
smooth, with a slight median ridge but no denticles.

The only spine at all resembling this one from British strata hitherto described
is the Dipriacanthus of M‘Coy (Brit. Paleeoz. Foss.,” p. 627, pl. 3, K., fig. 18), and
it only approaches it in the possession of denticles along the anterior margin ; it is
quite distinct in form and general outline.

Gnathacanthus triangularis, Davis.
(Pl ADVIL, figs 11)

Spine, imperfect ; length preserved 1-75inches, greatest breadth‘35. inch. Boththe
basal and apical extremities are wanting and it is an uncertain approximation that
the spine may have been four and a half to five inches in length. In transverse
section the spine is triangular, the base, formed by the posterior aspect being
half the length of the two sides, and the apex or anterior portion forming an
acute but somewhat rounded angle. The lateral surfaces are straight or slightly
depressed ; they are divided into six or seven rows of raised, pustulate, enamel-
coated tubercles, circular in form and extending longitudinally along the surface ; the
tubercles appear to have been only superficially implanted, many of them having
been removed, leaving a hollow space to mark their former position. Between each
row of tubercles there is a small ridge extending parallel with them. Anterior
''364 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

surface rounded and narrow, studded with denticles of two sizes, the larger are
about 35 inch apart and extend ‘1 inch from the surface, inclining slightly towards
the apex of the spine. The basal portion of the denticle is round and smooth ;
The apex acuminate, with a series of minute ridges extending from the point down-
wards. Between each of the large denticles there are three or four smaller ones,
resembling the larger onesin miniature. Posterior surface slightly concave, fibrous,
minutely and irregularly pitted, with a median ridge, small but well-defined. The
postero-lateral angles are closely studded with minute enamel-tipped tubercies.
The internal orifice is large, partaking generally of the external form of the spine.
Whether it formed an external sulcus at the basal portion of the spine, or was
enclosed with a terminal opening only, the spine is not well enough preserved to
show.

Formation and locality : Mountain Limestone, Armagh.
Ex coll. Kari of Enniskillen.

Gnathacanthus striatus, Davis.
(PL XLYVAdL» fie. 12.)

Spine, imperfect; base wanting, part preserved 1-6 inches in length, greatest
breadth °3 inch, at basal extremity. Slightly curved posteriorly, gradually
tapering towards the superior extremity which terminates acutely. Transverse
section, triangular, the sides meeting at an acute angle to form the anterior margin,
base shorter than sides, internal cavity large and oval. Lateral surfaces ornamented
by aseries, six or eight, of longitudinal, enamelled, strong, inosculating ridges. The
anterior margin is occupied by a row of closely-implanted compressed denticles, wide
at their base, curved downwards, and sharply pointed. Each of the latero-posterior
margins also possesses a line of denticles, smaller and finer than the anterior ones, also
curved downwards and separated from each other by about double their own
diameter.

The species differs from the previous one in its less decidedly triangular form and
more especially in the ornamentation of its sides. The pustulate enamel-coated
tubercles of G. triangularis are replaced by a much more decided series of ridges than
occurs in that species. The anterior row of denticles and the general form of the
spine, however, are sufficiently characteristic to renderits genuine position undoubted.

Formation and locality : Mountain Limestone, Armagh.
Lex coll. Karl of Enniskillen.

Genus.—Cladacanthus, Agassiz. MS.

Cladacanthus—L. Agassiz, 1833. “ Poissons Foss.,” Vol. IIL, p. 176. (MS.)
Krismacanthus—M‘Coy, 1848. “Ann. Nat. Hist.,” 2nd ser., Vol. II., p. 119.

‘Spine, of three divaricating portions; first, a large, compressed, finely striated base,
which entered the flesh ; secondly, a short, strongly compressed, rapidly tapering
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 365

spine, curved directly backwards, the sides marked with strong, smooth, longitudinal
ridges, and having two rows of short, downward-curved teeth on the posterior con-
cave margin ; thirdly, a peculiar prop-like portion extending directly forward nearly
at right angles with the base, gently arched downwards, compressed at the basal half,
depressed at the distal half, closely covered with blunt, smooth, oval tubercles, and
with some large irregular spines on the under side ; the portion of the base above
the flesh, and from which these two portions branch, is irregularly tuberculated.”
—(M‘Coy.) The anterior portion of the spine terminates in an enlarged process
studded with four or five terminal tubercles of larger size than on any other portion
of its surface.

This very peculiar ichthyodorulite was first named by Prof. Agassiz and recorded
without description in the “ Poissons Fossiles.” The specimens were in the collection
of the Earl of Enniskillen, at Florence Court, where they have remained to the present
time. Prof. M‘Coy afterwards described specimens of the same genus and species,
which he found in the collection of Capt. Jones, R.N.,in the “British Paleeozoic Fossils”
as Hrismacanthus jones. Priority being generally accepted as the guide in the
retention of synonymical names, in the present instance the generic name of Agassiz,
viz., Cladacanthus, must be adhered to.

Cladacanthus paradoxus, Agass. (indet.)

(Pl. XLVIL, figs. 1-5.)

Cladacanthus paradoxus—L. Agassiz, 1837. “ Rech. sur 1. Poiss, Foss.” Vol. ITI., p. 176 (indet).

es 2 C. G. Giebel, 1848. “Fauna der Vorwelt,” Vol. I., pt. 3, p. 310.

~ pe H. G. Bronn, 1848. ‘‘ Nomencl. Paleont.,” p. 303,

Erismacanthus jonesii— F. M‘Ooy, 1848. ‘‘Ann.& Mag. Nat. Hist.,” 2nd ser., Vol. IT., p.119.
Dipriacanthus faleatus— 5 1848, = ze sid ac p eR et NOL EL ide!
Cladacanthus paradoxus—H. G. Bronn, 1849. “ Enumerator Paleont.,” p. 653.

3 9 J. Morris, 1854. “Catal. Brit. Foss.,” p. 321.
Dipriacanthus faleatus— “ 1854, : a t p. 325.
EKrismacanthus jonesii— 7 1854. . P 5 p» 326,

. 3 F. J. Pictet, 1854. “Traité de Paléont.,” Vol. IL, p. 293.
Dipriacanthus faleatus— y 1854. a . a Vol, 12, p, 292,
Erismacanthus jonesii—__ F. M‘Coy, 1855. “ Brit, Paleoz. Foss.,” p. 628, pl. 3 K, figs. 26, 27.
Cladacanthus paradoxus—Morris & Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. XVIIL., p. 100.
Dipriacanthus falcatus— y i 1862. - * 2 1 VO eV ees ie LOE
Erismacanthus jonesii— 6 1862. a s x VO. AVELU LOO,

s , St. John & Worthen, 1875. “Paleont. of Illinois,” Vol. V Le peed,
Cladacanthus paradoxus—J. J. Bigsby, 1878. “Thesaurus Devon.-Carbonif.,” p. 349.
Dipriacanthus faleatus— 3 1878. a % 9 p. 355,
Erismacanthus jonesii— Z 1878. ia ¥ i p- 355,

The following description of this spine is taken from the admirable one given by
Prof. M‘Coy, with some modifications rendered necessary by the observation of a
large suite of specimens in the Enniskillen and other collections.
''366 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

‘Posterior spine, three times as long as wide, breadth near its attachment main
tained for about one-third its length, remaining two-thirds rapidly contracted, deeply
curved, and ending in a fine point. Sides much compressed with a variable number,
four tonnine, of longitudinal ridges, which are smooth and less than their own diameter
apart, the intervening spaces occasionally longitudinally striated ; along the anterior’
margin there is a weli-defined carina; posterior concave surface with two regular
close rows of small pointed denticles, directed obliquely downwards ; the surface
towards the base is marked by small, scattered, oval, smooth tubercles, anterior
branch more than twice the length, and about the same size at its origin, as the
posterior one ; a transverse section shows the height of the anterior branch to be
double its width at the basal ‘half, but it becomes depressed, so that its width is
double the height in a section of the distal half; an internal cavity extends almost
to the distal extremity, it is large compared with the diameter of the spine; it is
covered above and on the sides with close quincuncially arranged, smooth, oval
tubercles ; near the extremity the spine becomes abruptly expanded and is covered
with tubercles of much larger size, the extremity is generally curved downwards ; the
basal partof the spine from which the two branchestaketheir originis equaltothe width
of their united bases, this is maintained for a short distance downward, after which
the base becomes expanded to one and a half times its diameter above. The upper
part is covered with smooth, rounded, shining tubercles, scattered indiscriminately ;
lower, the base is much compressed and finely striated. with an abruptly truncated
termination.

The length of the base is 1:4 inch, its width at bottom 1:1 inch, near the top ‘7

inch. The length of the posterior portion of the spine is 1:5 inches and that of the
anterior 3°2 inches.

Formation and locality: Mountain Limestone, Armagh.
Lx coll. Karl of Enniskillen.

Cladacanthus major, Davis.
(El AVAL... fies. 6, 7.)

Fragments of a second species of this peculiar genus of fish-remains occur at
Armagh and may be consulted in the Enniskillen collection. They consist of portions
of the longanterior part of the spineand include one example showing the extremity of
this portion of the spine. By comparison with (’. paradoxus, Ag., this one was about
three lines larger. The anterior portion of the spine which js preserved is much
compressed. Its lateral surfaces are covered with circular tubercles arranged in
lines roughly parallel to the anterior margin. The tubercles are individually covered
with minute dots or punctures only observable when highly magnified. The greatest
breadth of the part of the spine preserved is *65 of an inch and at that point there
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain, 367

are eleven rows of tubercles on one side. The walls of the spine are thin and it
appears to be owing to this that they are so much compressed. The diameter between
the sides is little more than one-fourth that between the anterior and posterior margins.
The anterior margin is formed by a strong carina of shining ganoine, ‘1 of an inch
across. The posterior one is not well defined but appears to have been devoid of
denticulations. |

Another specimen exhibits the extremity of the longer branch of the spine, an
impression is preserved a little over two inches long, the extremity is well preserved
and exhibits somewhat similar peculiarities to that of C. paradoxa, Agass. The
diameter of the stem of the spine taken from the impression on the matrix is ‘4 of
an inch : half an inch from the extremity the spine becomes suddenly expanded to
‘9 of an inch. At its distal end it is divided into four toe-like prolongations, each
of which is covered by asingle large plate of ganoine, oval in form and ‘2 of an inch
across the longer diameter. The body of the spine was coated with enamelled plates
of unequal size averaging ‘1 of an inch across, and without definite arrangement.

This species is distinguished from Cladacanthus paradoxus by its much larger
size.

Locality : Mountain Limestone of Armagh.
Lz coll. Earl of Enniskillen.

Genus.—Physonemus, Agass. MS.
Physonemus—A gassiz, L., 1833. ‘ Poiss. Foss.,” p. 176, MSS.
i M‘Coy, F., 1855. “ Brit. Paleeoz. Foss.,” p. 638.

“ Fin spine, much compressed, with a variable backward curvature ; base of inser-
tion large ; posterior edge with two rows of small denticles. Surface covered with
very numerous cord-like longitudinal ridges, which swell at short regular intervals
into small bubble-like tubercles.” —(M‘Coy).

Professor Agassiz named the spines of this genus. Professor M‘Coy formulated
the description, from which the above is taken.

Physonemus arcuatus, M‘Coy.

(Pl. XLVIL, fig. 8.)

Physonemus arcuatus—F. M‘Coy, 1848. “Ann, & Mag. Nat. Hist.,” 2nd Ben, ¥ Ol, Pu pee
fe . J. Morris, 1854. “Catal. Brit. Foss.,” p. 338,
3 , F..J. Pictet, 1854, “Traité de Paléont.,” Vol. II., p. 291.
x F. M‘Coy, 1855.“ Brit. Paleeoz. Foss.,” p. 638, pl. 3 L., fig. 29.
Pe . Morris and Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. XVIIL, p..10!,
5 os J. J. Bigsby, 1878, ‘Thesaurus-Devonico.—Carb.,” p. 363.

“ Spine, slightly imperfect at the distal extremity, probably half an inch missing
—remaining portion 5‘5 inches in length along the convex surface. Two-thirds the
length of the spine was exposed, the remaining third was embedded in the bedy

TRANS, ROY. DUB. SOC., N.S., VOL. I. 5 30
''368 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

of the fish. The line separating the two parts extends obliquely from the convex
to the concave surface, with apparently the contrary direction usually observed on
fish-spines. The inner or concave margin, which was probably the posterior one,
was less deeply implanted in the integuments than the anterior one. The curvature
of the anterior margin forms the arc of a circle exceeding one-third its circumference ;
its greatest diameter is ‘9 inch at the junction of the base with the exposed surface.
The base is large and expanded, more or less bilobate, much compressed. The
exposed portion gradually tapers towards the point, and if perfect would probably .
terminate acutely. The lateral and anterior surfaces are covered by numerous
rounded longitudinal ridges, “less than their own diameter apart, dilated into
rounded, smooth, bubble-like tubercles, which are nearly twice their diameter apart ;
some of the tubercles occasionly flattened and transversely oblong ; the narrow
sulci between the ridges have usually two or three obscure longitudinal striz ; on
the posterior edge are two irregular alternating rows of obtusely pointed tubercles,
finely stellated by radiating strize at base, and about one line in diameter.”

A large and massive spine, Physonemus gigas, N. and W., a foot or more in
length, and two inches in diameter has been described by Messrs. Newberry and
Worthen (“ Geol. Survey of Illinois,” Vol. VL, p. 373. pL ii, fig. 1). It is from the
Burlington Limestone, and very closely related to Physonemus arcuatus, M‘Coy ; its
large size and an obliquely conical form of the stellate posterior tubercles being
the only differences. The authors named above, consider that the curvature of the
spines of this genus is reversed, the concave surface being the anterior one and
vice versa ; the correctness of this supposition is very doubtful and it appears most
probable that the spine is bent backwards in the ordinary manner, the denticles are
extended along the concave surface, and there is a decided groove between the two
rows in some of the specimens. The diverse obliquity of the line of demarcation
between the basal and upper portions of the spine, may easily be accounted for by
the form of the spine, and is such as would naturally accrue from its great
curvature.

Formation and locality : Mountain Limestone, Armagh.
Hex coll. Earl of Enniskillen.

Physonemus subteres, Agass. MS.
(Fly MEVIL ie 12!)

Physonemus subteres—L. Agassiz, 1837. “Rech. sur]. Poiss. Foss.,” Vol. III., p.176, indet.
i; i” J. E. Portlock, 1843, “Rept. Geol. Londonderry, é&e.,” p. 461.
o » « Ox G. Giebel, 1848. “Fauna der Vorwelt,” Vol. I. pt. 3, p. 310.
” ” H. G. Bronn, 1848. “Nomencl. Paleont.,” p. 972.
” ” ” ~ 1849. “ Enumerator Paleont.,” p. 653.
a. ” J. Morris, 1854. . “ Catal. Brit. Foss.,” p. 338.
2 ” F. J. Pictet, . 1854. “ Traité de Paléont.,” Vol. IL, p. 291.
” ” F. M’Coy, 1855. “ Brit. Paleoz. Foss.,” p. 638, pl. 3, L, fig. 30.
” ” Morris & Roberts, 1862. “Quart. Journ. Geol. Soc.” Vol. XVIIL., p. 101.

” » J. J. Bigsby, 1878. “Thesaurus, Devonico-Carb.,” p. 363.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 369

This species, like many others, was named by Prof. Agassiz but left undescribed.
A specimen, which very doubtfully belongs to this genus, is figured in M‘Coy’s
“ Brit, Palzoz. Foss.,” p. 638, pl. 31, fig. 30. It is described as “a fragment five lines
long, straight, without perceptible tapering, one and a half lines wide, about four
ridges in the space of one line ; the intervening spaces being rather wider than the
ridges themselves, which swell at alternate intervals into oval, smooth tubercles,
about their own diameter apart: intervening spaces with about three longitudinal
punctured striz. The species is easily distinguished from the P. arcuatus by its
small dimensions, slender tapering form, and straightness ; two small rows of teeth
on the posterior side.”

The original specimen, named by Prof. Agassiz, Physonemus subteres, is in the
Jones’ collection at the Geological Society. It is 2°0 inches in length and less than a
quarter of an inch in diameter. The specimen is imperfect at each end, and the
portion preserved is in great part embedded in the matrix. The sides are covered
with a series of longitudinal ridges with intermediate hollows about the same
diameter as the ridges. The latter are coated with enamel and are, at intervals,
slightly produced so as to form a bead-like irregularity of the surface. The pos-
terior surface, which is in part exposed, is hollowed into a longitudinal groove. The
angle formed by the side and back of the spine is devoid of denticulations. |

The specimen does not present the characteristic features of the genus Physonemus
as defined above. It has far more the appearance of a Ctenacanthus, but in default
of better preserved examples it is perhaps premature to remove it to that genus.
It may have been a portion of a long spine like the one figured of P. attenuwatus.

Formation and locality : Mountain Limestone, Armagh.
Hx, coll. Geological Society, London.

Physonemus attenuatus, Davis.

(Pl. XLVIL,, fig. 10.)

Spine, broad and strong near the base, rapidly tapering and acuminate towards.
the superior extremity. Jt is six inches in length along the outer curvature. The
exposed portion of the spine is imperfect, and in great part broken away. The
surface was striated longitudinally. The base gradually expanding downwards is
widest at the extremity being 1°3 inches, and apparently produced on its posterior
surface to form an acute angle, this appearance however, may be due te imper-
fection in its preservation. The internal cavity is large near the base of the spine
but becomes very small towards the point, and terminates before reaching it.

This species is very distinct from any hitherto described. Its long attenuated
form, and the peculiar expansion of the basal region renders its determination
easy.

Formation and locality ; Mountain Limestone, Armagh,

Ex coll. Earl of Enniskillen.
802
''370 On the Fossil Fishes of the Carboniferous Iimestone Series of Great Britain.

Physonemus hamatus.

(Pl. XLVIL, figs. 9, 11.)

Onchus hamatus—L, Agassiz 1837. “ Rech. sur‘les Poiss, Foss.” Vol. T1L, p. 9, -pl. 1,
figs. 7, 8.
C. G. Giebel, 1848. “Fauna der Vorwelt,” Vol. I., pt. 3, p. 302.

H.. G. Bronn, 1848, “‘Nomencl. Palzont.,” p. 843.

fe es . 1849. “ Enumerator Paleont.,” p. 652:

a Fi J. Morris, 1854. “Catal. Brit. Foss.,” p. 334.

i; F, J. Pictet, 1854, “Traité de Paléont.,” Vol. IL, p. 284.

o - Morris, & Roberts, 1862. “ Quart. Journ. Geol. Soc.” Vol. XVIII. p. 101.
9 5) J.J. Bigsby, 1878. ‘Thesaurus, Devonico-Carb.,” p. 359.

Prof. Agassiz described this form as a species of Onchus in the following terms:
“Tt is distinguished from all other Ichthyodorulites by its strong curvature, which
forms almost a semicircle. It rapidly tapers towards the point ; the base is simply
but strongly indented and the internal cavity does not appear to extend the whole
length of the spine . . . . . The surface is finely striated and the strize are
smooth.”

The genus Onchus is described as composed of species resembling the Lias Hybo-
donts in all respects except that the posterior denticles are absent and the species
are generally small in size. One species (O. hamatus) differs from the remainder
in its peculiar form and want of ornamentation, and Prof. Agassiz, whilst leaving it
provisionally in the genus Onchus, expresses an opinion that it may be necessary to
constitute a new genus for its accommodation.

Though this species differs in some respects from the type in Prof. M‘Coy’s defi-
nition of the genus, notably in its want of surface ornament, its general form so
nearly approaches to Physonemus that it may be safely transferred from the genus
Onchus to occupy a position so much more congenial.

Several specimens of this species occur in the collection of the Earl of Enniskillen,
and also in the Museum at Bristol. They are all from the Black Rock limestone of
Bristol whilst all the specimens of Physonemus arcuatus and P. subteres have
been found in the limestone of Armagh.

Formation and locality : Mountain Limestone, Bristol.
Hx coll, Earl of Enniskillen,

Genus—Chalazacanthus, Davis.

Spine, medium size, strong, curved, tapering to a point, laterally compressed.
Base large, striated, open posterior cavity, which higher up is enclosed. Base
separated from the exposed portion by an oblique line. Surface of upper part
ornamented by tubercles devoid of definite arrangement.

This spine bears some resemblance to those of the genus Drepanacanthus
N.and W., and Xystracanthus, Leidy (‘ Proc. Acad. Nat. Science, Phila.,” 1859), but
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 371

if the diagnosis of these genera be correct, it is at once distinguished by the
direction of the line dividing the base from upper part of the spine, which in
Drepanacanthus (‘‘ Geol. Surv. Illinois,” Vol. II., p. 121) ‘slopes upward at an angle
of 45° from the concave to the convex margin,” so that the spine must have had an
inclination forwards instead of backwards. In the genus at present described the
spine was inclined in the ordinary way, backwards.

In the “ Fauna du Calcaire Carbonifere de la Belgique,” L. G. de Koninck describes
a genus Stichacanthus. In many respects it appears to be closely related with this,
but it differs in having all the tubercles arranged in longitudinal lines and attached,
the one to the other, by a prolongation of the surface ; they have also the posterior
border armed with a row of small oblique teeth directed towards the base. Mons.
de Koninck states that there is a specimen of this ichthyodorulite at the British
Museum. I have not observed, during recent visits to the collections at Cromwell-
road, such a specimen as he describes. :

Chalazacanthus verrucosus, Davis.

(PL Avi fo, 22)

Spine, about six inches in length, and less than one inch wide at its greatest
breadth midway between the two extremities, moderately curved, the anterior
margin more so than the posterior, the two somewhat rapidly converging near the
apex. ‘Transverse section triangularly cone-shaped, sides much compressed and
about twice the length of the base, latter hidden by matrix, the two sides meet
anteriorly and form an obtusely rounded surface without keel ; the basal portion of
the posterior surface forms a deep cavity ; higher it is enclosed and extends nearly
the whole length of the spine. Base imperfect, slightly tapering, osseous, striated.
Length along the anterior margin 1°8 inches, and about three inches posteriorly.
Line dividing the basal from the exposed part decidedly oblique with convex
curvature towards the base. The striated character of the base is continued some
distance along the posterior margin. Exposed surface ornamented by a large
number of tuberculations without definite arrangement, occasionally forming into
oblique rows, at other places longitudinal ones ; the tubercles are less distinct near
the apex of the spine.

A second specimen, in the Enniskillen collection, probably belongs to this species,
it is imperfect and indistinct, but appears to conform generally to the description
given above. In transverse section it is much less compressed laterally, and the
external tuberculation is more proniinently developed. It is from the Mountain
Limestone of Armagh.

Formation and locality : Lower Carboniferous Limestone, Black Rock, Avon, Bristol.
Ex coll. British Museum.
''372 On the Fossil Fishes of the Carboniferous Limestone Series of Great Briton.

Genus Cladodus, Agass.
Cladodus—A gassiz, 1833. ‘ Poiss. Foss.,” Vol. IIT., p. 196.
M‘Ooy, 1855. “ Brit. Palzoz. Foss.,” p. 619.

“ Teeth, with a broad, horizontal, semicircular, thick, bony, coarsely-fibrous base,
rounded behind, truncated in front ; crown divided into long, sharp, subulate, conical
points, arranged along the straight truncated edge of the base; medial cone mucl:
larger than the secondary ones, of the latter the external cones are largest ; all the
cones striated longitudinally, and either circular in section or with simple cutting
edges, slightly compressed.” —(M‘Coy).

In Prof. Agassiz’s definition of the genus all the characters pertaining to the
base are omitted. He points out the great resemblance existing between the teeth
of Cladodus and those of Hybodus of the more recent Lias formations. There is
the same slender form of the median cone and foldings of the enamel—the same
relations between the root and the crown. ‘The median cone in both is flanked on
each side by secondary cones, but with this difference, that instead of decreasing
in size from the median cone, towards the lateral extremities, they present an in-
verse disposition, the largest secondary cones being situated at the extremity of
the base and diminishing in size towards the median one. 7

So far as known, all the species of Cladodus are confined to the Carboniferous
rocks, so that they may be looked upon as the forerunners of the genus Hybodus,
which makes its appearance in the rocks of Triassic age.

Cladodus mirabilis, Agass.

(Pl. XLIX., figs. 1-5.)

Cladodus mirabilis— Agassiz, L. 1833. ‘ Poissons Foss.,” Vol. IIT., p. 197, pl. 22 B, fig. 9-13.
= ; Portlock, J. E. 1844. ‘Geol. Report, Fermanagh, é&e.,” p. 461.
% : Giebel, C. G. 1858. “Fauna der Vorwelt,” Vol I., pt. 3, p. 322.
3 > Pictet, F. J. 1854. “'Traité de Paleont,” Vol IL. p. 258.
a sy M ‘Coy, F. 1855. ‘“ Brit. Paleeoz. Foss.,” p. 619.

5 5 D’Eichwald, E. 1861. ‘ Lithea Rossica,” p. 1604.

* Morris & Roberts, 1862. ‘Quart Journ. Geol. Soc.,” Vol. XVIIL., p. 100.

o - Rowanowsky, H. 1864. “Bull. de la Soc. Imper. des Nat. de Moscou,” Vol.
XXX VI1., p. 166, pl. iv, igol.

ef y Young & Armstrong,1871. “Trans. Geol. Soc. Glasgow,” Vol. IIL, supt., p. 69.

Teeth vary considerably in size and form. Base semicircular, very thick and
coarsely osseous, extending more or less horizontally at right angles to the cones
forming the crown. The under side of the base is concave in the centre, the root
of the crown conforming to, and laying parallel above it. Crown consists of central
cusp aud an irregular number of bilateral secondary ones, usually two on each side.
The median and secondary cones are thick, circular and strongly attached to the
base, abruptly tapering and ending in a more or less acuminate apex slightly
inclined backwards. The lower pcrtion of each cone is deeply but finely striated,
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 373

the ridges becoming obliterated, especially in large and mature teeth, towards the
summits, A large example measures 1°5 inches across the base; the latter extending
in a semicircle ‘75 of an inch backwards. Height of median cone ‘9 inch, width
at base ‘4 inch. There are three lateral cones on each side, the outermost largest.
In other specimens the median cone is considerably thicker and more robust, and
there are generally two cones only on each side of the principal one. They are more or
less cylindrical and devoid of cutting edge.

This species was regarded by Prof. Agassiz as the type of the genus. A magni-
ficient series exists in the Enniskillen collection from which the beautiful teeth,
on Plate XLIX., have been selected.

Formation and locality : Carboniferous Limestone, Armagh.
Ex coll. Earl of Enniskillen.

Cladodus marginatus, Agass.
(PY XULX nee 70)

Jladodus marginatus—A gassiz, L. 1838, ‘ Poiss. Foss.,” Vol. IIL, p. 198, pl. 22. B, fig. 18-20.
% levis—M ‘Coy, F. 1848. “Ann. Nat. Hist,” 2nd ser., Vol. IL, p. 133.
»  marginatus—Portlock, J. E. 1844. “Geol. Rept. Londonderry, &c.,” p. 461.
2 93 Giebel, C. G. 1848, “Fauna der Vorwelt,” Vol. L, pt. 3, p. 323.
- : Pictet, F. J. 1854. “Traité de Paleont,” Vol. IIL., p. 258.
y5 leevis— os a pia ’ Vol. IL, p. 258.
ie He Moy, F. 1855. “Brit. Paleoz. Foss.,” p. 619, pl. 3 K, fig. 5.
. marginatus— . - 4 - eee.
3 5 Morris & Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. XVIIL., p. 100.
a leevis— 55 . . 3 ‘ i ol. BNE palo.
‘ . Young & Armstrong, 1871. “Trans. Geol. Soc., Glasgow,” Vol. IIL., supt., p. 69.

Teeth, base, strong, broadly expanded, concave, fitting to the base of the crown.
Crown, median cone large, thick and strong, generally inclined at an oblique angle
to the base, obtusely pointed, somewhat compressed, with a raised cutting edge
along each side, surface finely striated in specimens not greatly worn. Two
secondary cones on each side, terminal cones divaricating, slightly larger than the
intermediate ones, short, broadly expanded at the base, obtuse, striated same as the
median cone. |

Several specimens are much worn by using, the cones being reduced to a short
stump. Jn such instances every trace of the surface striation is removed and the
teeth present a perfectly smooth appearance. The smooth teeth were considered
by Prof. M‘Coy as separate species, whilst C. merginatus, he included in the species
©. mirabilis, Ag. In both these determinations there can be little doubt that Prot.
M-Coy erred. Cladodus marginatus as defined by Prof. Agassiz is quite distinct
from C. mirabilis of the same author, no amount of wearing would reduce the long,
cylindrical, distinctly-separated lateral cusps of the latter to the form presented by
the tormer, in which the cusps are united together by their bases. In all particulars
''374. On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

the C’. levis, M‘Coy, agrees with the much-worn, smooth specimens of C. marginatus
given above.

Formation and locality: Mountain Limestone, Armagh.
Ee coll, Earl of Enniskillen.

Cladodus elongatus, Davis.

(tr AULA, ee 10,71)

Teeth, large, very prominent median cone, variable number of lateral cones,
those placed externally considerably the largest. Base large and expanded, sub-
elliptical, more or less rounded behind ; anterior margin straight with the exception
of the median portion which is curved inwards, rounded at the extremities,
moderately thick, diminishing in thickness backwards, lateral diameter of base 1°6
inches, from front to back, :7 inch. Median cone 1°3 inches in height with
sigmoidal curvature ‘3 of an inch wide at base, that width being maintained with
very slight diminution one half the height, it then tapers gradually and terminates,
in specimens not much worn, in an acutely pointed apex; transverse section, sub-
triangular; anterior surface slightly convex, laterally produced so as to form a
cutting edge; posterior surface deeply convex, with median angularity towards
the apex; anterior and posterior surface uniformly striated. Lateral cr secondary
denticles number five on each side. The two external ones are large, firmly
implanted, accuminate, striated similarly to median one; they are *45 inches in
length slightly and sigmoidally curved with points deflected outwards. Intermediate
cones small, equidistant, -15 of an inch long. In addition to the more prominent
denticles indicated, there are, in very well preserved specimens, others very minute
and apparently interspersed without definite arrangement.

This species is distinguished by its largely expanded, flat base, and the peculiarly
long and graceful proportion of the median tooth. In general form it most nearly
approaches Cladodus striatus, Ag., from Tynan in Ireland ; it differs from that species
in the characters just indicated. This- species also bears some resemblance to
examples found in the lower Kinderhook fish-beds of Llinois, especially Cladodus
alternatus, St. J. & W.,(“Geol.Surv. Ill.,” Vol. VI., p. 265, pl. 2, figs. 14-18. This may
be distinguished, however, by the alternate secondary denticles being of unequal
length, and its smaller size. C. grandis, N. & W. (“Geol. Surv. Ill.,” Vol. IL, p. 29
pl.L, fig. 15), similar in form, is separated by its compressed form of median cone and
the irregular arrangement of the secondary ones.

Formation and locality, Mountain Limestone, Richmond and Settle.
Lx coll. Reed collection, York Museum.
''On the Fossil Fishes of the Carboniferous Limestone Serics of Great Britaan. 375

Cladodus striatus, Agassiz.
(Pl. SIX tes. 12 18s

Cladodus striatus—A gassiz, L. 1838. ‘“ Poiss, Foss., 7 Vol: IIL, p..197, pl. 226, fie, 14-17,

5 ‘ Portlock, J. E., 1844. “ Geol. Rept. on Londonderry, &c.,” p. 461.

. 5 Giebel, C. G., 1848, “Fauna der Vorwelt,” Vol. I., pt. 3., p. 323.

i 5 BronnyHy.G:; 1848. “ Nomencl. Palzont.,” p. 305.

5 3 Pictet, F. J., 1854. “Traité de Paléont.,” Vol. II., p. 258.

6 55 Morris, J., 1854. “Cat. Brit. Foss.,” p. 322.

aa M‘Coy, F., 1855. “ Brit. Paleeoz. Foss.,” p. 620.

. a Morris and Roberts, 1862. “Quart. Jour. Geol. Soc. London,” Vol. XVIIL.,
p. 100.

5 . Young & Armstrong, 1871. “Trans. Geol. Soc., Glasgow,” Vol. III., Supplement.
p. 69%

De Koninck, L. G., 1878. “Fauna du Cale. Carb. dela Belgique.”

Teeth, base semicircular, large, moderately thick, and undulated at the rounded
edge with a few obtuse, irregular, radiating furrows below, and obscurely nodose
above. Width 1 inch to 1:25 inches broad, from middle of flat side to middle of
convex margin ‘6 inch. In front, the base joins to the crown with a median sinus
the junction being marked by an overlapping ridge. Crown; median cusp long,
comparatively slender, moderately compressed, in a few instances slightly sigmoidal
flexure, in others nearly straight or slightly curved backwards, Lateral edges
smooth and sharp ; the anterior and posterior surfaces of the cusp striated more
closely than in other species, apex smooth and sharply pointed.

Lateral cones, six or more on each side, of irregular size, but very small, terminal
ones larger, *2 to ‘3 of an inch long, and ‘1 of an inch wide at the base, pointed out-
wards, in addition to the secondary cones there is frequently a number of still smaller
projections interspersed indiscriminately—they are only seen, however, in well
preserved specimens.

The distinguishing characters of this species is to be found in the large number
of small lateral cones or cusps, and the more than usually deeply striated surface of
the median one.

The teeth comprised in this species do not bear more than a generic resemblance
to any of the previously described British species. Three or four species described
by Messrs. St John and Worthen, from the fish-beds of the Kinderhook Limestone at
Burlington, Iowa, appear to be similar in form and to possess near relationship with
them. Amongst the American species, Cladodus wachsmuthi, St. J. and W.
(*Palecon. HT,” Vol. VI, p. 262) p) 2 fies 1-7) ; C. succinctus, St. J. and W. (op.
cit., p. 265, pl. 3, figs. 8-12) ; C. alternatus, St. J. and W. (op. cit., p. 265, pl 2, figs.
14-18) ; and C. springer, St. J. and W. (op. cit., p. 259, pl. 2, figs. 1-13), are each
characterized by a more or less broad base, with a large central cone, and a series of
smaller lateral cones on each side of it. The lateral cones, however, in each species

are much longer than those of C. striatus, as well as being either angular or compressed
TRANS, ROY. DUB. SOC., N.S.. VOL, I. 3P
''376 On the Fossil Fishes of the Carboniferous Limestone Serves of Great Britain.

*n section. The beautiful series of C. wachsmuthi approach nearer perhaps than
cither of the others, the base, as represented in 9p. cvt., fig. 3b, and the series of lateral
denticles or cones approach very nearly to the specimen from Tynan, but in
proportion to the width of the base the denticles are larger, whilst the central one
is considerably shorter in proportion to its diameter.

Formation and locality : Mountain Limestone, Armagh, Tynan, in Ireland ; also in Derbyshire, at
Lowick, Northumberland, and Brigsteer near Kendal, in each case rare (M‘Coy); Upper Wensleydale.

Lower Limestone, Howrat, Dalry, West of Scotland (Young and Armstrong.)
Ex coll. Earl of Enniskillen.

Cladodus curvus, Davis.
(PL AUIX,, fig. 14)

Teeth, small or medium size, base not well exposed but apparently rather slender
for the size and strength of the coronal superstructure. The latter is formed by
three large cones, the central one is the largest, nearly half an inch in length and
about equal to the breadth of the base, it has a double curvature, first bending
forwards and nearer the apex curving round in a lateral direction to the left : the
cone is strong, rotund, ‘15 inch in diameter near the basal extremity, gradually
contracting upwards and terminating in an acute point. The surface is deeply
striated longitudinally, the ridges well defined with an acuminate edge separated
by a wide sulcus. The ridges divide but without anastomosis. The lateral cones
are unequal in size, the one forming the right extremity of the tooth being nearly
equal in size to the central one, whilst the opposite one is smaller; the latter is
straight half the length of the central cone, and extends at an angle of 45° from
the base, it is striated similarly to the central one. The right lateral cone is only
slightly smaller than the central one, it is straight and rises almost vertically from
the base. It is separated from the central cone by a larger interspace, on which —
there may have been located a small denticle but which is not now present, than
the opposite one. The crown is separated from the base by a transverse sulcus and
ridge extending across the tooth.

The peculiar want of symmetry in the arrangement of the cones of this species
renders it quite distinct from any other. It is placed in the genus provisionally
because the base being hidden by the matrix it is impossible to form a safe opinion
as to whether it possesses the broadly expanded base characteristic of the genus.

Formation and locality : Mountain Limestone, Armagh.
Ex coll. Far] of Enniskillen.

Cladodus destructor, Davis.
(PL XULX, fig, 15.)

Teeth, of large size, 1:25 inches across the base and 1 inch in height, strong and
robust. Base. large and thick, elliptical in outline, “6 inch wide, extending laterally
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 377

beyond the surface covered by the crown ; base inclined with slight obliquity back-
wards.. Crown divided into three large cones equal in size, and equidistant.
Central cone, circular in section, slightly constricted at the base *4 inch high, ‘3 inch ~
in diameter, conical, tapering, acuminate, upper portion of cone sigmoidally curved
backwards. Surface finely striated, ridges coated with shining enamel are
bifurcated repeatedly from the point to the base. ach lateral cone is about the
same size as the central one and in all respects appear its counterpart. The
structure of the coronal portion of the tooth is close, hard and dense, it is thickly
coated with enamel : the basal part is a porous somewhat fibrous bony structure.

The peculiar and somewhat abnormal form of this unique specimen is sufficiently
characteristic to distinguish it from any other species hitherto described. It
possesses the broadly expanded base characteristic of the genus Cladodus. Its
central and two lateral cones of nearly equal size differ very much from the ordinary
form with comparatively large central cone, and lateral series of small ones, but
there does not appear to be any sufficient generic distinction necessitating the institu-
tion of a new genus.

Its nearest ally is the species Cladodus curvus, previously described from the
same formation at Armagh. The two are, however, quite distinct, the irregular and
unsymmetrical arrangement of the cones in the latter render it easy to distinguish
from this species.

Formation and locality : Mountain Limestone, Armagh.
Ex coll. Ear) of Enniskillen.

Cladodus acutus, Agass.

(EL XE Bey)
Clododus acutus—A gassiz, L. 1838. ‘“ Poissons Fossiles,” Vol. III, p. 199, pl. 22, fig. 21.
Portlock, J. E. 1844. “Geol. Report, Londonderry, &c.,” p. 461. .
Giebel, C. G. 1848. “ Fauna der Vorwelt,” Vol. I., pt. 3, p. 323.
Pictet, F. J. 1854. ““ Traité de Paléont.,” Vol. IL., p. 258.
M ‘Coy, F. 1855. “ Brit. Palseoz. Foss.,” p. 620.
Morris & Roberts, 1862. “ Quart. Journ. Geol. Soc.,” Vol. X VIII, p. 100.

This species was described from a unique specimen by Prof. Agassiz, and, so far,
the specimen remains the only one known.

“The principal cone is sharp and subulate, more conical than cylindrical, and
slightly inclined backwards; its base is large and the point sharp. The secon-
dary cones are of medium height, two on each side, striated similarly to the median
one. The edge of the principal and lateral cones is produced so as to form a sharp-
cutting surface. The base of the crown is hollowed out in the middle. Root short,
and parallel with the base of the crown.”—(Agass).

Prof. M‘Coy considered that thisspecies might have been youngspecimens of Clado-
dus mirablis, Ag., but afteracareful examination of a large number of specimens of the

latter, there appears to be a sufficiently well marked specific difference in the sharp
3P2
''378 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

lateral cutting-edge of C. acutus to distinguish it from any other species. The me-
dian cone of Cladodus striatus is possessed of a sharp cutting-edge, but there can be
io hesitation in distinguishing between the teeth of that species and the present one.

Formation and locality : Carboniferous Limestone, Loughgall, near Armagh.
Ex coll. Jones collection, Geological Society’s Museum, London.

Cladodus milleri, Agass.
(A 21AX, fe. 16.)

Cladodus milleri—Agassiz, L. 1838. ‘ Poiss. Foss.,” Vol. III, p. 199, pl. 226, figs. 22, 23.
Sphenonchus subulatus—A gassiz, MS., in collections.
Cladodus milleri—Giebel, C. G. 1848. “ Fauna der Vorwelt,” Vol. III., pt. 3, p. 323.

. - Pictet, F. J. 1854. ‘ Traité de Paléont.,” Vol. IT., p. 259.

Gs Morris & Roberts, 1862. ‘ Quart. Journ. Geol. Soc.,” Vol. XVIII., p. 100.
: i Young & Armstrong, 1871. ‘Trans. Geol. Soc., Glasgow,” Vol. III., Supt. p. 69.

Teeth. “The teeth have a great external resemblance to Cladodus mirabilis : the
principal cone in particular approaches very near the same form, it is cylindrical, very
slender and appears to have been obtuse at the summit. This cone is striated ; the
strie are much finer and more regular than C. mirabilis: the secondary cones are
also more slender, either vertical or recurved backwards. Root is not well pre-
served. The base of the crown is undulated. The length of the tooth equals or
exceeds the height of the principal cone.”

An example of C. miilert, which is broken across the tooth, is represented in
(Pl. XLIX, fig. 16). It is 1-4 inches in length, the principal cone is *6 inch. There
are three secondary cones on each side, the median one strongly implanted, rapidly
tapering and acuminate. The principal cone in this specimen, terminates in a sharp
point. This specimen differs somewhat from the description of Prof. Agassiz, the
median cone is not so high or obtusely pointed, and the lateral cones are of more
regular size and three instead of two in number.

Formation and locality : Mountain Limestone, Bristol.
Ex coll. British Museum.

Cladodus conicus, Agass.

Sphenonchus conicus—Agassiz, L. MSS. in British Museum.
_ Cladodus es Agassiz, L. 1838. “ Poiss. Foss.,” Vol. III., p. 199, pl. 226, fig. 24.
; 5 Giebel, C. G. 1848. “ Fauna der Vorwelt,” Vol. I., pt. 3, p. 323.
3 Pe Pictet F. J. 1854. “ Traité de Paléont.,” Vol. IT., p. 259.
es 5 Morris & Roberts, 1862. “ Quart. Journ. Geol. Soc.” Vol. XVIII, p. 100.
fe 3 Young & Armstrong, 1871. ‘“ Trans. Geol. Soc., of Glasgow,” Vol, ITI., Supt.,
p- 69.

Prof, Agassiz distinguished this tooth from the Mountain Limestone of Bristol,
under the name of Sphenonchus conicus ; finding it should be included in the genus
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain 379

Cladodus he transferred it there. The example is stated to be unique. It is im
perfect and a doubt is expressed as to whether it is a separate species. The principal
cone is insensibly contracted towards the point, and in this it differs from C. miller,
Agass., with which it was found. The folds of enamel are not so fine and the base
of the tooth is not so large. Secondary cones not present. I have not been able
to find the type at the museum at Bristol, where Prof. Agassiz states it was
located.

Formation and locality : Mountain Limestone, Bristol.

Cladodus basalis, Agassiz MSS.
(PE XL. te. 18.)

Cladodus basalis,—Agassiz, L., Captain Jones’s Collection MSS.
3 - Portlock, J. E., 1844. “Geol. Report Londonderry, &c.,” p. 461.
A Se Morris and Roberts, 1862. ‘ Quart. Journ. Geol. Soc.,” Vol. XVIII. p. 100

Teeth, comparatively small, base broad as central cone is long, breadth of base
is ‘4inch. Median cone broad at the base, gradually tapering, curved backwards,
anterior basal surface depressed and concave, surface above marked by a series of
longitudinal ridges, broad and strong, separated by grooves about equal to them in
width. Apex of cone much worn by attrition. Lateral secondary cones small,
‘1 inch in length, two on each side, the external ones little if any larger than the
intermediate ones ; striated in the same manner as the central cone.

The type specimen of this species was named by Professor Agassiz whilst
in the collection of Admiral Jones, and was afterwards transferred to the
Museum of the Geological Society. It presents somewhat similar features to
Cladodus mirabilis, but more careful examination prove some points of difference.
The tooth appears to be full grown judging from its worn appearance, and must
consequently have belonged to a smaller fish than the great teeth of C. mirabilis
The longitudinal ridges are much thicker and stronger than, those of other species
and do not present any of the thread-like appearance of the ridges on C. mirabilis.

Formation and locality : Mountain Limestone, Armagh.
Ex coll. Geological Society’s Museum.

Cladodus curtus, Davis.
(Pl. XLIX., fig. 19.)

Teeth, very broad strong base, median cone short, secondary cones small and
numerous. Anterior surface of base only exposed ‘9 of an inch broad, under
surface flat, front rounded on each side with median depression. Crown, median
cone ‘3 of an inch in height, 25 inch wide at the base ; higher it becomes rapidly
smaller and ends in a sharp point, surface broadly striated. Secondary denticles
''380 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

small, broadly and strongly implanted, converging to a finely pointed apex. Two
extreme cones are the largest, they extend away from the centre.
This specimen appears to be unique.

Formation and locality : Mountain Limestone, Richmond.
Ex Keed Collection, Museum, York.

Cladodus hornei, Davis.
(Pl. RA, dip 209)

Tooth, medium size, 1°1 inch across the base, 1 inchin height. Base, subelliptical,
thin, anterior face slightly rounded, depressed in centre, extending backwards at
right angles to the median cone. Median cone long, tapering, with a slight double
flexure, compressed from back to front ; junction of anterior and posterior surfaces
from a lateral cutting edge; surface covered with longitudinal ridges about their
own diameter apart; near the apex it is smooth, apparently the result of wear,
towards the base the ridges become more numerous and smaller, then disappear.
Two lateral cones ‘3 of an inch in length, round, divergent, pointed, striated similarly
to median cone. Space between the median and lateral cones depressed and smooth.

This comparatively rare species stands apart from others of the same genus in
its graceful attenuity and paucity of secondary denticles. It probably approaches
near to Cladodus striatus, Ag., from the Armagh Limestone, to C. elongatus, Davis,
from Richmond in Yorkshire, and to C. elegans, N. and W., from the St. Louis
Limestone (Geol. Survey of Illinois, Vol. IV, p. 354, pl. iv., fig. 9). From the
latter it is distinguished by the central cone being rounder, less compressed, and
its attachment to the base less expansive and thinner. The general form of the
tooth is similar to C. elongatus, but it is readily distinguished from that species by
the presence in the latter of a large number of lateral cones. The same character
also separates it from C. striatus as well as its more slender and feebler form.

T am indebted to Mr. William Horne, an enthusiastic naturalist, for the oppor-
tunity to describe this species, and as a tribute towards my indebtedness I venture
to distinguish the species by appending his name.

Formation and locality : Carbonifercus Limestone, Wensleydale.
Ex coil. William Horne, Esq.

Cladodus mucronatus, Davis.
(Pl. XLIX., fig. 21.)

Teeth, medium size, breadth of base ‘8 of an inch, height of median cone ‘5 of
an inch. Base thick, median portion, beneath central cone, deeply hollowed,
abruptly prominent on each side, retreating and terminating in an acute extension
projecting some distance beyond each extreme lateral denticle. Crown composed
of a central cone, with five lateral cones, two on one side, three on the other, the
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 381

outermost of which are largest; central cone widely implanted, rapidly tapering
and terminating in an acutely pointed apex. Surface covered with longitudinal
ridges, bold and prominent, about twenty in number near the base, diminishing to
five or six near the apex. Secondary denticles, terminal ones largest, divergent,
broad at the base, conical, slightly curved, pointed, striated as median cone ; inter-
mediate denticles small.

This species, with its sharp, regularly conical cusps and deeply sulcated base, is
readily distinguished from Cladodus mirabilis, Ag., which is the only species which
it nearly approaches.

Formation and locality : Carboniferous Limestone, Wensleydale.
Ex. coll. William Horne, Esq.

Genus.—Carcharopsis, Agass. MSS.
Carcharopsis—Agassiz, L., 1833. “Rech. sur les Poiss. Foss.,” Vol. III., p. 313.

Teeth, length equal to twice greatest breadth ; form triangular, broad at the
base converging to a pointed apex, straight or slightly bent towards one side ;
transverse section elliptical or ovoid ; antero-posterior diameter equal to half the
lateral one; lateral margins deeply crenulated. Base somewhat constricted and
less than the diameter of the basal portion of the crown, divided more or less into
two branches with a deep intervening sulcus.

Prof. Agassiz in a foot note to the synoptical table of Squalides (‘Poiss. Foss.,”
Vol. IIL, p. 313), makes the following brief reference to the teeth of Carcharopsis
prototypus :—“I have designated under this name a very extraordinary type of
tooth, obtained from the Carboniferous Limestone of England and Ireland, of which
I shall give a description in the supplement of this work. In their general form,
the teeth of this genus strikingly resemble those of the genus Carcharodon ; they
are equally compressed, triangular and denticulated along their edges, bat the
surface presents large folds towards the base of the crown. The genus appears to
approach that of Petalodus of Owen, of which it may be necessary to form a separat
family. The only example I have seen of Carcharopsis prototypus forms part of
the collection of the Earl of Enniskillen.”

From the above references to the resemblance of the new genus to those of Carcha-
rodon and Petalodus there can be little doubt that the tooth which is here described
as the type of the genus from the collection of the Earl of Enniskillen, and which
has been $0 labelled during many years past, is the example which Prof. Agassiz
intended to indicate. This being the case it necessarily follows that the determina-
tions of some American paleontologists will require considerable revisions and
modification.

Prof. M‘Coy (British Palszoz. Rocks and F ‘ossils,” p. 642, pl. 3 G, fig. 2, ati
pl.3 K, fig. 11) describes two species of teeth which he considers form a genus possess-
ing distinctive characters from others previously discovered. ‘They are named’

ered relent ea ag ee eg ne nme a Ra aa ie i al
''382 On the Fossil Fishes of the Carboniferous Ivmestone Series of Great Britain.

Pristicladodus and are described as consisting of a crown composed of one large,
thick, compressed, sharply-pointed cone, with two denticulated cutting edges, the
surface highly polished and either smooth or very finely striated; the base of the
cone expands at right angles, forming a large semicircular, thick, coarsely osseous
pase from which there may be extended a single lateral cone on each or not. The
teeth agree generally with those of Cladodus in the form of both base and crown,
the latter, however, differs in the greater robustness of the principal cone, and
especially in the denticulation of its edges. Prof. M‘Coy remarks, “ The first specimen
which I saw of this genus I supposed might have been the Carcharopsis prototypus
of Agassiz’s lists, but subsequently finding a second which was still more nearly
like Carcharodon, to which he likens his species, I hesitated to identify an un-
described fossil which I had never seen, more especially as neither of my specimens
showed any trace of the ridges at the base of the crown alluded to by Agassiz ;
and the horizontally dilated base was so remarkable a character, totally separting
them from Carcharodon, and nearly allying them to Cladodus, that I could not
suppose that the true Carcharopsis prototypus was identical with my fossils, or the
one resemblance would not have been stated and the other affinity overlooked.”
Two species are described, P. dentatus, triangular in outline, cone sharply pointed,
base widely expanded and laterally tapering to a point without cones. This species
is distinguished from the second one, P. goughi, by the strong, close, deeply-cut,
regular dentation of its edges, and the deep triangular depression in the anterior
face. The P. goughi is larger, it has a central and two lateral cones, one on each side.

In 1866, Newberry (‘‘Geol. Surv. Illinois,” Vol. II., p. 69, pl. VI., figs. 14, 14a)
described a tooth from the Alabama Limestone very similar to the Pristicladodus
of M‘Coy. It is recognized as offering a near relationship to that genus, but
though the name Pristicladodus is regarded as well chosen to indicate the relation-
ship of the genus, he considered that it was anticipated by perhaps the equally
appropriate one of Carcharopsis of Agassiz. The latter is therefore retained, the
tooth being called C. wortheni.

In 1875, Messrs. St. John and Worthen (Geol. Survey of Illinois”, Vol. VL., p. 253)
amended the genus Pristicladodus of M‘Coy. The P. dentatus of that author is
regarded as the type of the genus Carcharopsis of Agassiz and P. goughi, M‘Coy
retained as the type of the genus Pristicladodus. The genus Carcharopsis as thus
amended is described, its principal features being the widely expanded central cone,
sublenticular in transverse section, the lateral angles sharp and deeply and regularly
crenulated : extremities occupied by one or two more or less slender, conical lateral
denticles, which are as isolated as in the case of the typhical Cladodus. The amended
genus Pristicladodus is characterized by the central cusp being strong, erect, sig-
moidally recurved, rapidly converging to a point, “ lateral edges sharp and more or
less distinctly undulated or simple: lateral cusps relatively very strong, sometimes
even more massive than the median cusps, divergent, similar in shape to the median
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 388

prominence, with which they are connected by a prominent sharp-curved intervening
ridge ; anterior coronal surface marked with sharp more or less irregular cost, which
converge intheintermediate crest, producingafaint denticulation, sometimes forming
quite strong spinous processes.” The form described by Dr. Newberry under the name
of Carcharopsis worthent, is regarded as a typival representative of the genus first
recognized by Prof. Agassiz, and intimately allied to, though probably specifically
distinct from Pristicladodus dentatus of M‘Coy, whether the latter is identical with
the original form named by Agassiz Carcharopsis prototypus or not, the authors have
not been ableto ascertain, but “in assigning to each of those groups appellations which
we believe to have been originally upplied to quite different forms, in part at least;
by Profs. Agassiz and M‘Coy, we have been guided by such facts as are accessible
to us, only desiring to render due justice to our own authorities.”

After consideration of the several descriptions given above, it appears that the
Carcharopsis of Agassiz was a tooth consisting of a crown formed of a single cusp or
cone, deeply plicated or folded towards the base, the latter was much contracted in
size compared with the diameter of the crown. M‘Coy’s genus Pristicladodus is
also well defined, having a broadly expanded horizontal base resembling Cladodus,
and in some instances a single lateral cone on each side the central one : the type
species, C. dentatus, however, was not possessed of lateral cones. The specimens
described by Newberry as Carcharopsis wortheni bear so close a resemblance to
Pristicladodus dentatus, M‘Coy, that there can be no doubt that it should be trans-
ferred to that genus. The genera Carcharopsis, Ag., and Pristicladodus, M‘Coy,
have one characteristic common to both, the central cusp is deeply serrate on each
side, butinthe amended descriptionsgiven by St. Johnand Worthen (“Tlinois,” Vol. VL.,
p. 254), and indicated above, the lateral edges of the central cusps of the teeth in-
cluded in the latter genus are “more or less distinctly undulated or simple,” and
the only species described, P. springeri is possessed of lateral cusps which are larger
than the central one, and the edges of the central cusp are smooth. This divergence
of characters warrant the doubts expressed by the authors as to the relationship of
the specimens, and leads to the conclusion that they must be excluded from the
genus Pristicladodus as defined by M‘Coy.

Carcharopsis colei, Davis.
(PE. XLS, figs 26.)

Tooth, length -9 inch, breadth near the base °45 inch, transversely elliptical or
ovate in section, the lateral diameter being about twice that of the postero-anterior
diameter. Broadest near the base, the tooth converges gradually to form an
accuminate apex, curving slightly to one side, and has a generally triangular form ;
anterior surface of the crown, transversely convex, longitudinally, along the median
line, nearly straight, curving slightly towards the apex : at the basal extremity the

TRANS. ROY. DUB. 80C., N.S., VOL. I, 3Q
''384 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

crown slightly converges and is divided into two branch-like roots with a median
depression intervening. Laterally the crown is divided on each side into about a
dozen deeply-cut crenulations: the latter strongly implanted, round, club-shaped,
and curved towards the apex of the tooth : they are largest in the central portion
of the tooth becoming smaller upwards, the point being without crenulations.
The coronal surface is smooth and enamelled. The base short, convergent, divided
into two branches which are less in diameter than the crown of the tooth.

Formation and locality : Mountain Limestone, Armagh.
Ex coll. Earl of Enniskillen.

Genus.—Pristicladodus, M‘Coy.
Pristicladodus—-M ‘Coy, F., 1854. ‘“ British Paleozoic Fossils,” p. 642.

“Base of tooth expanded at right angles to the crown, large, sub-semicircular,
thick, coarsely osseous ; from the truncated straight edge of the base in front the
crown rises as one large, thick, sharply-pointed, compressed cone, with two denti-
culated cutting edges, lateral cones very few (? one on each side or none), surface of
crownhighly polished and marked with fine longitudinal ridges, orsmuoth.”—(M‘Coy).

Pristicladodus dentatus, M’Coy.
(Pie) fie, 22")

Pristicladodus dentatus—M ‘Coy, F., 1854. “Brit. Paleoz. Foss.,” p. 642, pl. 3 G., fig. 2.
= 3 Morris and Roberts, 1862. “ Quart. Journ. Geol. Soc.,” Vol. X VILL., p. 101.
= - J. J. Bigsby, 1878. “ Thes. Dev.-Carb.,” p. 363.

Teeth, “medial cone large, triangular, rather flattened on the outer side, and.
with a deep triangular hollow, the base of which is parallel with, and a little above
the base of the tooth, which is narrow, arched upwards in the middle, and not prom-
inent ; the sides of the hollow are parallel with the sides of the tooth; back of the
crown rounded, sharply convex ; cutting edges set with a row of strong, equal, sharply-
defined, sub-cylindrical, obtusely pointed teeth, set at right angles to the edge (about
three in the space of one line), about half their diameter apart, and rather longer
than wide; base on inner side horizontally extended, thick, fibrous, almost semi-
circularly rounded; surface of large cone smooth on the outside, faintly striated
longitudinally on the inner side.”—(M‘Coy). ‘The specimen described by Prof.
M‘Coy was an imperfect one. The one now figured shows that the lateral extensions
of the base from the central cone, were devoid of secondary denticles. It is 1°4
inches across the base, height of cone ‘9 of an inch.

The specimen selected for illustration is from the collection of Wm. Horne, Esq.,
others occur in the Reed collection at the York Museum, and in Lord Enniskillen’s
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 385

collection at Florence Court, (now at the British Museum, Cromwell-road), and
also at the Natural History Museum, Newcastle-on-Tyne.

Formation and locality : Carboniferous Limestone, Wensleydale and Pateley Bridge in Yorkshire ; Black
Up. Carb. Limestone, Derbyshire.—(J‘Coy.)

Ex coll, Wm. Horne, Esq.

Pristicladodus concinnus, Davis.
(PL XETX, fe. 23.)

Teeth, small, imperfect, breadth of base when complete ‘4 of an inch, height of
median cone equals the width of base. Base expanded, thin, slightly crushed, crown
consists of one median cone, upper central portion accuminate, rounded, with lateral
~ cutting edge ; lower portion expanded on each side to the same width as the base ;
surface enamelled, smooth, cutting edges minutely and beautifully denticulated, a
fold between each denticulation is continued along the surface of the tooth. Anterior

face convex, no lateral or secondary cones.
This beautiful little tooth differs in details from Pristicladodus dentatus, it has

nevertheless features in common with the genus, and it appears advisable to retain
it in the genus, at any rate for the present.
Formation and locality : Carboniferous Limestone, Wensleydale.

Ex. coll. Wm. Horne, Esq.

Pristicladodus goughi, M‘Coy.
(Pl, XLIX, figs 27.)

Pristicladodus goughi—M ‘Coy, F., 1854. “Brit. Paleeoz. Fossils,” p. 643, pl. 3 K., fig. 11.
- - Morris and Roberts, 1862. “ Quart. Jour. Geol. Soc.,” Vol. X VIIT., p. 101
iu a J. J. Bigsby, 1878. “Thes. Dev.-Carb.,” p. 363.

Teeth, ‘“‘crown compressed, triangular, moderately convex, marked with close,
sharp, irregular, longitudinal strize, averaging five in one line, becoming obsolete
at the apex, and close to the base of the crown ; cutting edges sharp, marked with
broad, slightly-marked, tooth-like undulations, nearly their width apart, aud generally
blending at their base into the edge, being obsolete in the upper third of the cone ;
lateral cones two, robust, sub-cylindrical, striated like the principal one. Height of
principal cone, one inch two lines ; width of whole tooth, one inch three lines ;
width at base cight lines ; height of side cone five lines ; width at base three and a
half lines ; lateral breadth of base six lines ; lateral breadth or thickness of principal
cone four lines.” —(M‘Coy.)

This example, from the Lower Carboniferous schists of Kettlewell and Kendal,
located in the Woodwardian MuseumatCambridge, still remains unique. As already
pointed out, it differs very materially from the type species, P. dentatus. Itisa
rounded, robust tooth, with strong secondary cusps, whilst P. dentatus is deeply

compressed, and has no secondary cusps. The lateral denticulations of the median
8 Q 2
''386, On the Fossil Fishes of the Carboniferous Limestone Series of Great Britavn.

cone are, compared with P. dentatus, very weak, had they not been present the. .
tooth would have been a very exact representative of some species of Cladodus. It
is retained in its present position with grave doubts as to its generic identity.

Formation and locality : Lower Carboniferous schists of Kettlewell and Kendal.
Ex. coll. Woodwardian Museum, Cambridge.

Genus.—Glyphanodus, Davis.

Teeth, consisting of a single pointed, conical, excessively thin, crown, cutting edge
sharp, trenchant. Summit of crown inclined forwards. Surface ornamented by semi-
radiating strie, Base extending parallel with coronal surface, deep, coarsely osseous,
thin, equal in breadth to that of the tooth.

Glyphanodus tenuis, Davis.
(Pl. XLIX., figs. 24, 25.)

Teeth, medium size, triangular, very thin. Crown consists of a single,
conical, thin and laterally expanded surface, 1:0 inch wide at the base, and °7 of an
inch in height to the summit of the cone, gradually tapers to an accuminate apex.
Anterior surface convex, corespondingly concave posteriorly. Marked by a large
number of semi-longitudinal strize : indistinct or absent towards the base. ‘The strize
radiate to some extent from the centre of the tooth towards the lateral margins.
The ridges are bold, separated by their own diameter from each other. Cutting
edge sharp and smooth.

These teeth are peculiarly thin and slender. The base possesses more of the
characters of the Petalodonts, extending downwards in a line with the surface of the
crown rather than with the Cladodonts whose base extends backwards at right angles
to the crown. ‘The pointed surface of the crown, on the other hand, is more clearly
related totheCladodontsand especially with the modification found in Pristicladodus,
trom which however it is separated not only by the form of the root, but also by
the absence of denticulations, on the lateral surface of the crown,

Formation and locality : Carboniferous Limestone, Upper Wensleydale.
Ex, coll. Wm. Horne, Esq., and Reed collection, Museum, York

Family.—Orodontide, L. G. de Koninck.
Ref. “ Fauna du Calcaire Carb. de la Belgique,” p. 29, 1878.

Prof. Agassiz, in the “ Recherches sur les Poissons Fossiles,” pointed out and
insisted on the intimate relationship existing between the still surviving Cestracions
of the Australian and Chinese seas and the fossil genus Orodus of the Carboniferous
series. M. de Koninck (“ Fauna du Calcaire Carbonifére de la Belgique”) united
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 387

under the term Orodontide, the genera Orodus, Agassiz ; Lophodus, Rowanowsky ;
and Petrodus, M‘Coy : “parce que les dents des deux premiers de ces genres ont
une forme générale qui les rapproche les unes des autres, et que celles du troisiéme
ont une trés grande analogie par leur structure interne et par leur forme extérieure
avec les dents antérieures des Cestracion.” The Orodontide is regarded by M. de
Koninck as a group of the family Cestraciontide, but no further definition is given

The teeth of the genera comprised in the Orodontide, which have been found in
the Carboniferous rocks of the British Islands, are in nearly all cases quite dis-
sociated and separated into single specimens. In a few rare instances, as in
PL.L., figures 1 and 3, two or three teeth are found united antero-posteriorly, but in
no instance have teeth been discovered whose lateral extremities have been either
united or placed in such a relative position as to exhibit the method of arrange-
ment transversely ; neither have they served in any way to indicate how the teeth
were disposed on the jaws, or the number which existed in each fish, It is pro-
bable that the circumstances attending their deposition may account for the
separation of the teeth. The limestone, in which the specimens are found, would
naturally be a deposit which accumulated slowly, so that the body of the fish, with
the exception of the teeth and the spines, if they had any, being composed entirely
of cartilage and fleshy substances, easily decayed. As the connecting tissues
became decomposed, the teeth, released from their attachment, were disturbed and
more or less distantly separated by the action of waves or currents, and it was only
in rare instances that two or three teeth became embedded in the sediment with
sufficient rapidity to secure their preservation in natural juxtaposition, It is
fortunate that other specimens have been found in shales of the Coal Measures of
Osage County, Kansas, in America, which are well preserved, and retain the same
or nearly the same relative position to each other in the fossil state which they
bore when living. The deposition of the mud forming the shales doubtless pro-
ceeded with much greater rapidity and less disturbance than that of the limestones,
and the result has been that the fishes became buried in the sediment before a
sufficient time had elapsed for their decomposition and dispersion, and the hard
parts are preserved in a more or less natural and undisturbed state.

A consideration of the Kansas specimens throws much light on the nature and
relationship of the Orodontide as a group. They are described by Messrs.
St. John and Worthen, in the “ Paleontology of Illinois,” Vol. VI., p. 311, and are
considered by the authors as a separate genus, for which they have instituted the
name Agassizodus, in acknowledgment and recognition of the services of that
eminent ichthyologist. The specimen (op. cit., pl. vit, figs. 1-22) consists of
about four hundred and fifty to five hundred teeth in their natural position, and
comprises the whole of the left ramus of what appears to be the mandible or lower
jaw and a few teeth of the right mandible. After describing the arrangement of
the teeth, the authors remark that the teeth present “almost precisely the same
''388 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

appearance the spread out diagram of the dental armature of Cestracion would
present, as obtained by stripping off the teeth and spreading them upon a flat
surface. Hence in attempting the restoration (“Paleont. Illinois,” Vol. VI,
p. 312, pl. viii., fig. 22), it is obvious that sufficient allowance may not have been
made for the inrollment of the anterior portion of the jaw, thus producing an out-
line more obtusely angular in front than may have obtained in reality. Yet, com-
pared with the modern Cestracion, the jaws of the remarkable fish under considera-
tion were doubtless less acutely produced forward, and, in this particular, holding a
mean between its modern representativé and some of the Rays (e.g. Trygon) in the
relative obtuseness of the anterior extremity of the jaws. But the resemblance
here ceases. In all other respects, as the form of the individual teeth and their
arrangement upon the jaws, we observe unmistakable Hybodont affinities.” The
teeth are disposed in serial rows having a convoluted inrollment from the inner
to the outer border, and gradually increasing in size from the posterior extremity
to the row of large median teeth, anterior to which the rows are regularly
diminished in size towards the symphysis. In addition to the teeth, masses of
cartilage are preserved and certain peculiar little bodies of irregular form, but
generally more or less circular and delicately sculptured with irregular caring
radiating from the apex towards the marginal borders, concave below. These are
considered to have constituted the dermal or shagreen covering of the fish. No
spines have been found.

The teeth of Agassizodus present the closest affinities to those of the genus
Orodus, Agass., they are distinguished by the prevailing prominence of the
buttressed condition of the anterior coronal borders and the relative uniformity or
evenness of the posterior face, besides the relatively fewer rows of accuminate teeth,
as inferred from this feature being so prevalent in all collections of Orodi, while
the linear forms are least commonly met with. The genus appears to be confined
to the Upper Carboniferous or Coal Measure period, and it is not at all improbable
that this genus constitutes the representative of Orodus in these horizons, since
only a single form of the latter genus has been noticed from the Coal Measures and
that may prove to belong to the genus A gassizodus.

For comparison with the fossil forms, it may be well to cite the description of the
dentition of Cestracion given by Prof. Owen (“ Odontography,” p. 51). He says :
“The teeth at the anterior part of the jaws are smallest ; they present a transverse,
sub-compressed, conical figure, with the apex produced into a sharp point; these
points are worn away from the used teeth at the anterior and outer parts of the
jaw; but are strongly marked in those which still lie below the margin. There
are six subvertical rows of these small cuspidate teeth on each side of the jaw,
together with a median row close to the symphyseal line ; and from twelve to
fourteen teeth ina row. Behind the cuspidate teeth, the five consecutive rows of
teeth progressively increase in all their dimensions, but principally in their antero-
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 389

posterior extent ; the sharp point is converted into a longitudinal ridge, traversing
a convex crushing surface; and the ridge itself disappears in the largest teeth,
as the teeth increase in size they diminish in number in each row; the series of the
largest teeth includes from six to seven in the upper, and from seven to eight in
the lower jaw. Behind this row, the teeth, although preserving their form as
crushing instruments, progressively diminish in size ; while at the same time the
number composing each row decreases. From the oblique and apparently spiral
disposition of the rows of teeth, their symmetrical arrangement on the opposite
sides of the jaw, and their graduated diversity of form, they constitute the most
elegant tesselated covering of the jaws which is to be met with in the whole class
of the fishes.”

Comparing the above description of the still existent Cestracion and the Coal
Measures Agassizodus, a striking simlarity is observed in general form and arrange-
ment of the teeth on the jaws, as well as in the characteristics peculiar to the
teeth individually. It is only in matters of detail, in the number of the teeth in
each row, and the number of rows, that any striking difference is perceptible. The
dentition of Cestracion is adapted to crush hard and resistent objects like the
shells of the mulluscs, or the hard covering of crustaceans, and it is probable that
the teeth of the Orodonts were used for the same purpose.

Neither in American nor English strata have specimens been discovered which
illustrate more than the arrangement of the teeth. Whether the fishes possessing
them were possessed of defensive spines as in the case of the modern representative,
is unknown.

A comparison of the recent and fossil teeth will afford some idea of the great size
of the Cestraciont fishes of the Carboniferous age. The living fish found in the
Australian seas is two to three feet in length, and the jaws occupy about one-eight
of that length. The jaw of one of the larger specimens of Orodus ramosus must
have been at least three feet in length—if we may deduce the length of the jaw
from the relative size of the teeth—and the jaws being one-eighth the length of the
entire body, gives the latter at twenty-four feet.

The following British genera appear to possess characters which associate them
in one group and they are, along with the American genus Agassizodus, here included
in that of Orodontide :-— | ;

_ Orodus, Agassiz.
Lophodus, Rowanowsky.
Petrodus, M’Coy.
Agassizodus, St. John and Worthen.
Rhamphodus, Davis.
Diclitodus, Davis
''390 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britaan.

Genus.—Orodus, Agassiz.
Orodus—L. Agassiz, 1836. “ Poissons Foss.,” Vol. III., p. 96.

“Teeth, laterally elongated, having their middle portion more elevated than
their extremities, forming in the central portion of the tooth an obtuse and trans-
verse cone : the longitudinal transverse diameter, which much exceeds the transverse
(here called antero-posterior), is also marked by a ridge sometimes medial, sometimes
submedial, from which spring oblique secondary ridges which ramify upon the
sides, and which in the larger teeth, give rise to another series of collateral ridges.”

The teeth of the fishes of this genus vary greatly in form and; size they may be
longer or shorter, straight or strongly arched, strong and thick or slender and
attenuated, with large conspicuous roots or small ones, and in some instances appar-
ently rootless, and all from the same fish, differing according to their position in its
mouth. They appear, nevertheless, to have tolerable persistent similarity in the
surface decoration of the crown, and this character serves better than any other to
distinguish the several species.

The genus Orodus is entirely restricted to the Carboniferous rocks, so far as is
known. In the British Islands it is found in the Mountain Limestone and Yoredale
rocks, and may have ascended to the Coal Measures, specimens having been found
in the shales of the Lancashire coalfield which are attributed to this genus.

Orodus timidus, H. Trautschold, does not belong to this genus (L. G. de Koninck).

Orodus ramosus, Agass.

(PL L, figs. 1-7.)

Orodus ramosus—L. Agassiz, 1836. ‘ Recher. sur les Poiss. Foss.,” Vol. IIT., p. 97, pl. xi., figs. 5,
6, 7 and 8.
- . Sir P. Egerton, 1837. ‘“ Catalogue of Fossil Fishes.”
5 - J. HE. Portlock, 1843. “ Rep. Geol. of Londonderry, &c.,” p. 467., pl. xiv. a, fig. 8.
Be a L. G. de Koninck, 1844. “ Disc. der Anim. foss. du terre Carbonif., de la Belg.”
: p. 613, pl. lv., fig. 2.
cs a C. G. Giebel, 1848. “ Fauna der Vorwelt,” Vol. I., pt. 3, p. 342.
a c H. G. Bronn, 1848. “ Nomencl. Paleont.,” p. 852.
o ss F. Roemer, 1891. “H.-G. Bronn’s * Lethma.,” Vol.1., p. 709, pl. ix., fig. 9.
i 5 F. A. Quenstedt, 1852. “ Handb. der Petrefact.,” p. 188.
% Rs F, J. Pictet, 1854, “ Traité de Palxont.,” Vol. II., p, 264,
Ms ee J. Morris, 1854. “Cat. of Brit. Foss.,” p. 335.
5 3 Morris & Roberts, 1862. “ Quart. Journ. Geol. Soc,” Vol. XVIII, p. 101.
- H. Rowanowsky, 1864. “ Bul.delaSoc. Imp. des Natur. de Moscou,” p.158, pl. lil, fig. 2
” o Enniskillen, 1869. “ Alphab. Cat. of Type Spec. of Foss. Fish.,” p. 6.
: Be H. Trautschold, 1874. “ Die Kalkbriicke von Miatchkowa,” p. 16.
- v W. H. Bailey, 1875. “ Fig. Charact. Brit. Foss.,” p. 120, pl. xli., fig. 10.
%) ” F. Roemer, 1876. “ Lethexa paleozoica,” pl. xlviii., fig. 8.

3 »  L. G. de Koninck, 1878. “ Fauna du Cale. Carbonif. de la Belgique,” p. 30, pl. iv., fig. 1.
” ” J.J. Bigsby, 1878, “Thesaurus Devon.-Carb.,” p. 359.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 391

Teeth, large, powerful, massive: transverse diameter about three times that of
the antero-posterior one: median surface of crown broad, narrowing laterally to
two-thirds its diameter ; lateral terminations bluntly subtruncated. Median cone
prominent, with an acutely-angular antero-posterior ridge, on each side’ a median
carina somewhat sinuously descends to the lateral extremities, with divaricating
anterior and posterior ridges, the latter occasionally bifurcating into two or more
branches as they approach the margins. The carina and ridges in unworn specimens
are sharp and well defined, separated by deep and wide concave furrows. Surface
uniformly punctate. Base of crown irregularly concave. Root, very large, about
four times the depth of the crown, coarsely fibrous or spongy, full of lacunal
interstices. Anterior surface slightly convex, deeper than posterior which is
concave: base joins the two diagonally having nearly the same antero-posterior
diameter as the crown. Dimensions of a large example, transverse diameter four
inches, antero-posterior diameter 1°2 inches ; thickness of crown ‘2 to ‘4 of an inch ;
depth of base 1°1 inches.

The teeth of Orodus ramosus exhibit considerable variety in form as well as
surface ornamentation. In one of the largest examples Pl. L., fig. 2, the number
of bifurcating branches from the median lateral carina is very large and intricate. In
the same specimen the surface of the crown is so close in texture that only a very
shght trace of the punctuation is visible, though in other specimens of equal size
it is very easily perceptible. The series of three large teeth represented in Pl. L.,
fig. 1, from the Bristol Museum, appear to be much worn, both the median cone and
the lateral carina and ridges are almost obliterated. The specimen PI. L., fig. 1,
as well as the one represented by Pl. L., fig. 3, from the collection of Lord
Enniskillen, are interesting because they exhibit the relative position occupied by
the teeth in the mouth, the central cones in each case being contiguous, whilst
the lateral extensions are separated.

Professor Agassiz expresses a doubt as to whether the teeth of O. ramosus, and
O. cinctus, may not have belonged to one species. Professor L. G. de Koninck
appears also to consider that the two should be united (“ Fauna du Cale. Carbonif.
de la Belgique”). After avery careful examination of all the material available, how-
ever, it appears probable that the determinations made by Professor Agassiz in the
first instance are correct. The small specimens of O. ramosus are as distinctly ridged
as the larger ones (see Pl. L., figs. 6, 7), and throughout appear to possess the same
characters, whilst the smooth rounded forms of O. cinctus are equally persistent.

The teeth of Orodus ramosus, Agass., have been most commonly found at Bristol
in the black limestone. Specimens have also been obtained at Oreton, in Shrop-
shire, and a single specimen from Armagh exists in the collection given by the late
Admiral Jones to the Geological Society. The latter presents some features
differing from the Bristol specimens. Its transverse diameter is greater in propor-
tion to the antero-posterior one, and it is laterally much more attenuated. The

TRANS. ROY. DUB. SOC,, N.S., VOL. I. 3
''392 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

crown of the tooth is sub-triangular, the ridge being quite as far removed from the
base as the tooth is broad, whilst in the Bristol specimens, the teeth are broad and
much depressed. The teeth of O. ramosus from Oreton are beautifully preserved,
the surtace decoration being particularly distinct and clear. ‘he primary divaricat-
ing ridges are much fewer than in either the Bristol or Armagh forms, they are
irregularly branched, and, especially on the median cone, are somewhat complex.
The crown is slightly raised in the centre, due simply to the greater thickness of
the median cone, the base of the crown is approximately straight, and from the
summit of the median cone the lateral extensions gradually thin out, at the same
time the antero-posterior diameter becomes contracted and the termination is,
compared with the others, very acute.

The great fishes of this species which occupied the area around Bristol appear to
have had congeners in other localities, of smaller size and, so far as the teeth are
concerned, somewhat modified form; they do not present, however, sufficiently diver-
gent characteristics to warrant the supposition that they were not the same species.

Formation and locality : Mountain Limestone, Bristol ; Oreton ; Armagh.
Ex coll. Earl of Enniskillen ; Bristol Museum ; Museum of the Geological Society, London.

Orodus cinctus, Agass.
(PT. tee 8 9.)

Orodus cinctus—L. Agassiz, 1838. “Rech.s. les Poiss. Foss.,” Vol. III, p. 96,’pl. xi., figs. 1-4.
A J J. E. Portlock, 1843. ‘Geol. Report, Londonderry, &c.,” p. 467.
3 - C. G. Giebel, 1848. “Fauna der Vorwelt,” Vol. IL, pt. 3, p. 342.
ef is H. G. Bronn, 1848. ‘“Nomencl. Paleont.,” p. 852.
: A F. J. Pictet, 1854. ‘Traité de Paléont,” Vol. TI., p. 264.
5 3 J. Morris, 1854. ‘Catal. of Brit. Foss.,” p. 335.
9 3 Morris & Roberts, 1862. ‘Quart. Journ. Geol. Soc.,” Vol. XVIII., p. 101.

. 3 Young& Armstrong, 1871. “ Trans. Geol. Soc. of Glasgow,” Wot, HEPES supt:; o. 7s.
5 aS L. G. de Koninck, 1878. “Fauna du Cale. Carbonif. de la Belgique,” p. 31, pl. iv.,
fic. 2,

S J.J. Bigsby, 1878. “Thesaurus Devonico-Carb.,” p. 359,

Teeth, medium size, rounded and smooth, transverse diameter equal to four times
or more that of the antero-posterior one. Median surface of crown largely
developed, forming a rotund, smooth, somewhat detached cone, with a more or less
deep sulcus extending across the tooth antero-posteriorly. Lateral prolongations
of the coronal surface taper gradually towards each extremity which is usually
obtusely rounded. There is no central carina as in Q. ramosus. Three or four
rather deep sulci extend across the tooth from front to back, on each side of the
median cone, surface uniformly punctate. Root, large, laterally co-extensive with
the crown, about double the depth of the central cone ; structure, porous, vesicular.

Length of tooth 1:4 inches in lateral diameter, antero-postero diameter °35 inch,
thickness including base °6 of an inch.

This tooth is distinguished from that of Orodus ramosus by the absence of the
lateral median carina and in the general simplicity of its coronal surface.
''On the Fossil Fishes of the Carboniferous Limestone Serves of Great Britain, 393

An example from the Bristol Museum (Pl. L., fig. 8.) shows the position of four
teeth in natural sequence. The inner ones are almost straight, the lateral extremity
broadly expanded, whilst those placed externally are concavo-convex, narrow and
laterally somewhat more pointed.

This species is found in the bone-bed at the base of the Mountain Limestone at
Bristol, whilst O. ramosus is found only in the black limestone above.

Formation and locality : Mountain Limestone bone-bed, Bristol.
Ez coll. Ear] of Enniskillen ; Bristol Museum.

Orodus porosus, M‘Coy.
(Pl La fren 10.)

Orodus porosus—M ‘Coy, 1848. “Ann. and Mag. Nat. Hist.” 2nd Ser., Vol. IL, p. 131.
5 » F, J. Pictet, 1854. ‘Traité de Paléont,” Vol. II., p. 264.
pe #5 J. Morris, 185-4. “ Brit. Foss,” p. 309.
= . Morris & Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. XVIIT., p. 101.
a a J. J. Bigsby, 1878. ‘Thesaurus Devonico-Carb.,” p. 359.

Teeth, “‘sub-cylindrical, transverse diameter (or length of base) six or seven times
greater than the antero-posterior ; anterior and posterior margins nearly parallel,
the middle being scarcely wider than the ends, which are obtusely subtruncate ;
sides slightly tumid, converging to a narrow mesial ridge ; one small obtuse mesial
cone not exceeding the short diameter of the base in height, and forming an obtuse
ridge to the base on each ; on each side there are four or five smaller tubercles, the
smallest towards the ends, only those nearest the centre send one or two small ridges
down the anterior side, while the posterior is more regularly ridged: basal margin
tuberculato-plicate ; surface coarsely punctured, except on the prominent worn points
which-are smooth; transverse diameter usually about nine lines, short diameter
one and a half line.” —(M‘Coy.)

This species was described by Prof. F. M‘Coy in the “ Annals and Magazine of
Natural History,” without illustration, as was also Orodus compressus, M‘Coy.
Both form a part of the collection of types presented to the Geological Society by
the late Admiral Jones.

Orodus porosus, M‘Coy, most nearly approaches O. elongatus, Ag., in general
character. It may be distinguished from it, by the lateral ridges being produced
along the upper surface of the crown, with the carina, so as to form a number of
small secondary cones. The crown is also level and straight, whilst in O. elongatus
it is raised in the central portion to form a wide median cone.

~ Formation and locality : Mountain Limestone, Armagh.
Ex coll. Museum of Geological Society.

3R2
''394 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britavn.

Orodus compressus, M‘Coy.
(Pl. 1, Be. 1)

Orodus compressus—M ‘Coy, 1848, “Ann. and Mag. Nat. Hist.,” 2nd Ser., Vol. IL., p. 131.
s 53 EB. J. Pictet, 1854. ‘“Traité de Paléont.,” Vol. IL, p. 264.
S, + J. Morris, 1854. ‘Cat. Brit. Foss.,” p. 335.
. 5 Morris & Roberts, 1862. ‘“ Quart. Journ. Geol.-Soc.,” Vol. XVIIL., p. 101.
ay ~ J. J. Bigsby, 1878. ‘Thesaurus Devonico-Carb.,” p. 359,

Teeth, “much compressed, crown elevated into a thin edge of equal height
throughout, surmounted by a fine ridge, and festooned by four or five sharp points on
each side ; the centre has a large point, producing a globular swelling in the middle
of each of the flattened sides, over which it sends a small flexuous ridge, giving out
short branches on each side, while the lateral points only send short simple ridges
not half way down the sides; ends abruptly truncated; base surrounded by a
sharply defined thickened border ; surface smooth; highly polished ; root nearly
as deep as the crown is high; truncated below and at the ends; height of crown
one line, width of base three and a half lines.” —(M‘Coy.)

This species is one of the smallest found in Britain. The thin compressed edge
of the crown is a character possessed by Orodus carinatus, St. J. and W.
(“Paleeont. Illinois,” Vol. VL, p. 307, pl. v., fig. 24.) but the detailed surface markings
are quite distinct from that species.

Formation and locality : Mountain Limestone, Armagh.
Ex coll. Museum, Geological Society, Burlington House.

Orodus elongatus, Agass. (MSS.)
(Pr Ls fost 253)

Teeth, medium size, extremely long in proportion to the width; transverse
diameter 1°75 inches, antero-posterior diameter 25 of an inch in the centre, barely
more than *1 of an inch on each side, lateral terminations rounded. Central promi-
nence moderately elevated, with a ridge extending across from the anterior to the
posterior margins, lateral prolongations unequal, one more depressed than the other,
branching at right angles from the ridge across the central cone, two lateral ridges
descend to the right and left extremities respectively, from the lateral carina nume-
rous secondary ridges branch out on either side, of these the smaller disappear,
or two frequently converge, forming a Y-shaped fold, the lower portion of which
becomes attenuated or disappears before reaching the basal margin ; the latter
smooth and slightly sulcated. Root large, transversely a little wider than the crown,
central part and shorter extremity twice the depth of the crown, towards the
longer and more depressed extremity the root is proportionately smaller, base of
root smooth and straight, except a slight median concavity. Structure porous
and. open.

This species differs from Orodus angustus, Ag., in the possession of a median
carina and in the prominence of the central cone. It is also longer and more
''2

On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain, ‘395

attenuated in proportion to its length, the secondary lateral ridges are more regular
and symmetrical in arrangement. |

Formation and locality : Mountain Limestone, Armagh.
Fx. coll. Museum of Geological Society, London ; Earl of Enniskillen.

Orodus angustus, Agass. (MSS.)

(Pl. LL, fig. 4.)
Orodus angustus—L. Agassiz, “ MSS., Capt. Jones’ Collection Geol. Soc., London.”

7 - J. E. Portlock, 1843. “ Report Geol. Londonderry, &e.,” p. 461.

i Jd. Morris; = - 1854. “ Cat. Brit. Foss.,” p. 335.

- . Morris and Roberts 1862. ‘Quart. Journ. Geol. Soc.,” Vol. XVIII, p. 101.
és rr J.J. Bigsby, . 1878. “ Thesaurus Devonico-Carb.,” p. 359.

Teeth, medium size, uniformly narrow, transverse diameter 1:1 inch, width of
central cone ‘15 of an inch, laterally slightly less; lateral terminations rounded,
median elevation slight with an antero-posterior ridge, no lateral carina, numerous
ridges parallel with the median one, antero-posterior section circular, base of crown
contracted, surface uniformly punctate. Root slightly deeper than the height of
the crown, concavo-convex, base concave, corresponding to the convexity of the
crown, coarsely porous in structure.

This species, along with O. elongatus, O. gubbus, and O. catenatus, were ee
in Manuscript, by the late Prof. Agassiz from three specimens in the collection of
the late Admiral Jones. The types so named were presented to the Geological
Society, London, by Admiral Jones, and form the subjects of the present descriptions,
along with others selected from the collection of Lord Enniskillen.

The teeth of Orodus angustus, Ag., may be distinguished from those of O. elongatus,
Ag., by the absence of a lateral keel or carina, the more uniform diameter of the
tooth antero-posteriorly, the almost entire absence of a central cone and the
irregular arrangement of the ridges on each side. Similar characters also separate
it from O. porosus, M‘Coy. |

Formation and locality : Mountain Limestone, Armagh.

Bai coll, Earl of Enniskillen ; Museum, Geological Society.

Orodus catenatus, Agass. (MSS. Pe

(Pl. LI, figs. 5, ‘bai)
" Orodus catenatus—L, Agassiz, “ MSS., Capt. Jones’ Collection, Geol. Soc., London,”

” ” Portlock, » ete. “ Report Geol. , Londonderry, | &e. oa p- 461,
” 3 Morris and Roberts, 1862. “ Quart. Journ. Geol. Soc.,” Vol. XVIII., Pp 101,
” »” J. J. Bigsby, - 1878. “Thesaurus Devonico-Carb.,” P. 359,

Teeth, small, ‘35 of an inch in transverse diameter. Crown rises from each
lateral extremity with uniform gradation to the median cone. The latter is
prominent, round ; apex smooth, ofobatly from wear. Median ridge extends from
central cone along each lateral extension. ‘From the median ridge secondary: ones
''396 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

branch out anteriorly and posteriorly, each speedily bifurcating and afterwards
encircling the base of the crown after the manner of a chain. Root deeper than
the height of the crown ; anteriorly prominently convex ; posteriorly concave ; usual
porous structure.

This species appears to be sufficiently distinguished by its surface ornament and
small size. There is always the possibility that small specimens may be the teeth
of young fishes of other species, but in this instance such a probability is remote.
The teeth were named by Prof. Agassiz but not described or figured.

Formation and locality : Mountain Limestone, Armagh.
Ez coll, Kar] of Enniskillen ; and Museum, Geological Society.

Orodus gibbus, Agass. (MSS.)

CPE LL geo, 7)
Orodus gibbus—L, Agassiz “ MSS., Capt. Jones’ Collection, Geol., Soc., London.”

. i Portlock, 1843. ‘“ Report Geol., Londonderry, &c.,” p. 461.

S J. Morris, 1854. “Cat. Brit. Foss.,” p. 335.

: Morris and Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. XVIIL, p. LOL
os : J. J. Bigsby, 1878. ‘Thesaurus Devonico-Carb.,” p. 359.

Teeth, medium size, peculiar humpy form; transverse diameter 1-1 inch; antero-
posterior diameter of central cone ‘35 of an inch; lateral portions about half the
diameter of the central cone, with one or more secondary cones on each side;
lateral terminations obtusely rounded; base of crown much contracted antero-
posteriorly ; central cone large, gibbous, expanded prominently before and behind,
overhanging the base. The coronal surface contracts abruptly on each side for a
distance equalling the diameter of the median cone, when it becomes again ex-
panded to form secondary cones; occasionally there are two secondary cones on
one or both lateral extensions; surface smooth, uniformly punctate; base of the
crown slightly crenulated. Root equal in depth to the height of the crown and
co-extensive laterally; coarse spongy texture; anteriorly convex; posteriorly
deeply concave ; under-surface smooth.

The species, by its gibbous form, is readily distinguished. There are a number
of specimens in the collection of Lord Enniskillen which appear to belong to this
species, they are not so regular in furm as the types, and are much worn apparently
by attrition, the cones being reduced almost to the level of the remaining portion
of the tooth. One specimen affords evidence of having possessed a row of small
tubercles along the anterior basal margin of the crown.

Formation and locality: Mountain Limestone, Armagh.
Ex coll. Karl of Enniskillen, Museum of Geological Society.

Orodus sculptus, Davis
(Pi. Tl., ies; 8, 8a.)

Teeth, medium size ; transverse diameter 1°3 inches; from anterior to posterior
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britaan. 397

margins *3 inch ; raised portion of crown occupies a position nearer one end than
the other. Not marked by any different feature to the remainder of the surface
except that it is a little broader. An acutely raised ridge extends across the cone
and along the lateral extensions to the extremities. From this a large number of
minor ridges branch out at right angles. The latter frequently become broken
snto tubercles which extend over the surface mostly near the base. Root not
exposed.

This example is placed in the genus Orodus with some doubt; it appears to
possess many characters in common with other recognized members of the genus,
but in some respects it diverges considerably. The median cone is less developed
than in any other species and the tuberculated ridges are peculiar. It appears,
however, to approach Orodus nearer than Helodus or Lophodus.

Formation and locality : Mountain Limestone, Bristol.
Ex coll. Bristol Museum.

Orodus ornatus, Davis.

(Pl. LI, figs. 9, 9a.)

Teeth, small, transverse diameter 5 of an inch ; antero-posterior diameter ‘2 of
an inch ; crown consists of median cone with two or more lateral secondary cones
on each side. Median cone large, prominent, apex smooth, with a radiating series
of minute ridges or foldings of the enamelled surface, gradually absorbed in
the smooth surface lower down; a carina extends across the cone and is
continued laterally to the end of the tooth, it is tuberculated along its entire
length. The anterior and posterior basal margins of the crown are formed by a
series of folds in the enamel which are continued on the secondary cones. On
each side of the central cone is a deep depression from which the wall of the
secondary cone rises at a sharp angle, from its apex it slopes gradually to rise
again abruptly to form the next cone. An antero-posterior ridge runs across the
cones, which is also, in most cases, tuberculated similarly to the median carina.
Root not exposed.

This species approaches most nearly to O. moniliformis. It differs from itin the
greater thickness and breadth of the crown, the presence of tuberculate projections
along the lateral carina and the central cone, and in the form of the secondary
cones, which are not so round as in O. moniliformis, but present more the form of
an inverted cone.

The surface of crown of the tooth now described when magnified presents an
extremely ornate appearance which has suggested the nomen triviale applied to
the species.

Formation and locality : Mountain Limestone, Richmond, Yorkshire.
Ex coll, Ear] of Enniskillen.
''398 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

Orodus moniliformis, Davis.
(El LL fies. 10, 11, 12)

Teeth, medium, or small, transverse diameter one inch, central cone largest,
more or less circular, separated by a deep sulcus from the secondary cones, of which
there are four to six on each side, diminishing i in size towards each lateral extremity
of the tooth. Surface in small specimens smooth ; in larger ones, the apex of each
cone is minutely striated ; lower part corrugated trom the base of the crown upwards
but disappearing before reaching the apex. Between each corrugation there are
a number of small transverse plications, near and parallel to the base, which are
continuous from the central round the lateral cones. Root short, not so wide as
the crown, coarse in structure, containing numerous lacune.

This species is characterized by its somewhat flattened crown and short root, and
more especially by the semi-detached appearance of the cones forming the crown.

It bears a superficial likeness to Orodus mammillaris, N. and W. (‘‘ Paleeont. of
Illinois,” Vol. I., p. 66, pl. iv., figs. 10, 10a) ; the cones in the latter have a greater
vertical altitude, the ridges are more prominent and frequently beaded, of which
there is no trace in the Orodus now described. The root of O. mammillaris is also
shorter than in this one.

From Orodus ornatus, Dav., of the Richmond limestone, it is readily distinguished
by the absence of small Beenie along the lateral carina and central cone, which to
some extent are characteristic of that species.

Formation and locality : Mountain Limestone, Armagh.
Hx coll. Earl of Enniskillen.

radius reedi, Davis.
(Bly By » figs. 13, 18a.)

Teeth, small, probably ‘7 to.8 of an inch in transverse diameter ; height of
crown ‘2 of an inch, antero-posterior diameter about equal to the height of the crown,
median cone prominent, anteriorly and posteriorly dilated forming a bold ridge
from which minor ones branch right and left, reaching to the base, laterally
compressed : a carina extends from the median cone, on each side, at right angles
to the median one named ; bold ridges, separated by deeply channelled grooves,
branch out from the ential carina and descend to the base of the crown. At least
one secondary cone occurs on each side the median one and its ornamentation is
similar to the median one. Surface uniformly and coarsely punctate. Root,
concavo-convex, structure open and porous.

The peculiar arrangement of the ornamentation of this tooth (as shown on Pl. LI.,
fig. 13a) separates it from any other species hitherto described. It is very elegant
and though the extremities of the tooth are broken off, the part oo is well
preserved.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 399

The specimen is unique from the thick bedded Mountain Limestone of Settle, in
Yorkshire. It is comprised in the magnificent collection of fossils from the York-
shire limestone collected by the late Mr. Wood, of Richmond, and since purchased
by Dr. Reed, of York, and presented to the museum of that city. In recognition of
‘ the generous donor and his kind assistance to myself, I venture to attach his name
to this species.

Formation and locality : Mountain Limestone, Settle, Yorkshire.
Hx. Reed Collection, York Museum.

Orodus tenuis, Davis.
(FI, GL, fie. 14.)

Teeth, transverse diameter very long in comparison to that of the antero-posterior ;
crown, with a prominent median cone placed slightly towards one side, sub-rotund ;
lateral extremities depressed, expanded anteriorly and posteriorly to the basal
margins ; anterior basal margin prominent with slight tuberculations. A median
ridge extends from the central cone to the ends, terminating sub-acutely. Surface
smooth, coarsely punctate. Base, equal to crown in transverse diameter ; depth
equal to height of median cone, retreating from front, posteriorly-concave.

This species approaches nearly to Orodus elongatus but differs from it in the
absence of antero-posterior lateral ridges and the depressed form of the lateral
extensions of the crown.

Formation and locality: Mountain Limestone, Armagh,
Ex coll. Earl of Enniskillen.

Orodus subteres, Agass. (sp.)
(Pls LE; figs: 15, 502)

Psammodus subteres—L. Agassiz, 1833, _ “ Poiss. Foss.,” Vol. IIL, pl. xii., figs. 3-4,
Helodus is 3 1838. 5 3 55 »> p- 105, pl. xii., figs, 3-4,
‘9 PP E. G. Giebel, 1848, “Fauna der Vorwelt.,” Vol. I., pt. 3, p. 340.

3 é H. G. Bronn, 1848. ‘“Nomencl, Paleont.,” p. 583.

. a . 1849. “ Enumerator Paleont.,” p. 647.

$5 5 J. Morris, 1854. “Cat. Brit, Foss,” p. 328.

is es F. J. Pictet, 1854. “ Traité de Paléont.,” Vol. II., p. 267.

; Morris and Roberts, 1862. ‘ Quart. Jour. Geol. Soc.,” Vol. AV EIT, p. 100;
o s J. J. Bigsby, 1878. “Thesaurus Devon.-Carb.,” p. 357.

Teeth, “straight, very long, elevated medially forming an obtusely rounded
cone. The lateral portions are circular without ridges, uniformly covered with
minute pores. The margin of the longest end projects slightly, it is uniformly
punctate with the remaining surface.”—(Agassiz.)

Professor Agassiz observes that this tooth, which still remains unique, might be
taken for a gigantic example of Helodus levissimus, Agass., except that it lacks the
highly polished surface of the latter,

TRANS. ROY. DUB, SOC., N.S., VOL. I. 38
''400 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

This example, originally figured by Professor Agassiz as Psammodus subteres, and
afterwards described as Helodus subteres, appears in some important characteristics
to approach nearer to the teeth of Orodus than to those of Helodus. One of the
most important distinctions between the two genera consists in the form of the
base of the crown and its attachment to the root. In Helodus, the base of the
crown spreads out from the central cone, more or less in every direction, but
especially towards the anterior and posterior margins, forming in many instances
quite a concave flexure from the apex to the basal margins. The apex of the crown
is generally more or less acutely pointed or knife-like. The root of Helodus was
attached to the palate in a superficial manner as compared with that of Orodus, and
consists of a thin, deeply concave, often short, bony substance. On the other hand,
the crown of Orodus descends from the median cone and lateral surfaces with a
convex flexure, and the basal margins are incurved and rounded : the apex of the
cone is rounded, generally more or less bulbous, and the root is long, comparatively
thick and openly porous.

The specimen described by Agassiz as Helodus subteres has a median cone
which is obtusely rounded, the lateral prolongations, though not possessing the
median ridge which the Orodi generally do, is rounded and the basal margins are
incurved. There is also a portion of the root preserved which is decidedly Orodont
in appearance, It is thought advisable, notwithstanding the smoothness of the
surface to recognize the characters indicated and to transfer the specimen to the
genus Orodus.

Formation and locality : Mountain Limestone, Black Rock, Bristol,
Ex coll. Bristol Museum.

Genus—Petrodus, M‘Coy.
Petrodus—M ‘Coy, F., 1854. “ Brit. Paleeoz. Foss.,” p. 637.
“Teeth, conical, supported on a nearly circular osseous base, concave beneath ;
crown with a dense compact surface, height not exceeding the width, deeply
furrowed with rough radiating ridges.” —(M‘Coy.)

Petrodus patelliformis, M‘Coy.

(Pl. LL, figs. 16, 16a, 160.)

Petrodus patelliformis—F.M‘Coy, 1848. ‘Ann, and Mag. Nat. Hist.,” Second series, Vol.IT., p. 132.
J. Morris, 1854. ‘Cat. Brit. Foss.,” p. 337.
1855. “ Brit. Paleoz. Foss.,” p. 637, pl. 3G., figs. 6, 7, 8.

Teeth, “conical, height one-half to two-thirds the width of the base, which is round
or rarely subtrigonal ; apex rudely pointed, becoming flat by wear ; sides radiatingly
ridged with about thirteen or fourteen very strong, single or dichotomous ridges,
the sides of which are usually cut by numerous deep oblique sulci; the ridges are
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 401

highest at the base, where they terminate adruptly ; osseous base a little wider
than the crown. Diameter of base three or four lines.” —(M‘Coy.)

The specimens forming the subjects of this description are in the Woodwardian
Museum at Cambridge. They were obtained from the Mountain Limestone of
Derbyshire and are stated by Professor M‘Coy to be tolerably abundant in that
locality. I have not seen specimens in other collections or from other localities.

Two species have been found in the Coal Measures of Belleville, Ilinois (“ Geol.
Illinois,” Vol. IL, p. 70, et. seg.) ; one of very large size from the Burlington Lime- —
stone of Iowa, in America (“ Geol. of Illinois,” Vol. IV., p. 369). Specimens were
discovered in the Devonian rocks by M. Trautschold, who named them Ostinaspis
and considered that they were dermal tubercles, allied to those of the Rays; and
M. de Koninck has described a species from the Mountain Limestone of the neigh-
bourhood of Tournai, on the borders of Belgium (“ Fauna du Calc. Carb. de la
Belgique.” p. 37).

Prof. M‘Coy considered that the teeth of Petrodus approached more nearly in
microscopic structure to those of the living Cestracion than any others, and this
opinion appears to be shared by M. de Koninck, with regard to the Belgian
specimens. Messrs. Newberry and Worthen, who have described the American forms,
in accordance with a suggestion made by Prof. Agassiz, consider that these bodies
were not teeth, but the dermal tubercles of a fish probably resembling some of the
living Rays or of the Squalaraja polyspondyla figured by Prof. Agassiz from the
Lias of Lyme Regis (“ Poiss. Foss.,” Vol. III., pl. 43). The reasons on which this
supposition is based are, that the base is very thin and very flat, much more so
than in any Cestracionts, and too much so for the requisite solidity and stability of
teeth of which the function was the crushing of resistant substances. The base is
also laminated on every side forming a thin, sharp, finely crenulated edge, which
would prevent the teeth being in contact with each other, and in this respect offer a
strong contrast to other fossil forms of Cestracionts.

The teeth of Petrodus bear a close resemblance to those of Pleurodus from the
Coal Measures. The latter are thin, the base is very small, and deeply concave in
some instances, the edges are pectinated, and the surface is deeply ridged ; in all
these respects bearing a close analogy with the teeth of Petrodus; and as the Pleu-
rodus is undoubtedly a tooth, it may be assumed with considerable certainty that

Petrodus is a tooth also.

Genus—Ramphodus, Davis.

Teeth, medium size, laterally, triangularly elongated; lateral prolongations
unequal. Crown acuminate, recurved posteriorly; antero-posterior diameter,
small; coronal surface minutely punctate. Tooth bifurcates at right angles, one-

fourth its greatest length from the apex ; base small.
382
''402 On the Fossil Fishes of the Carboniferous Limestone Series of Great Brita.

Rhamphodus dispar, Davis.
(ei, EL fies 17) 7)

Teeth, Length from the pointed crest of the crown to the Jeft lateral extremity
is 11 inch: opposite side is ‘7 inch. The crown is produced and curved towards
the posterior face, presenting something like the appearance of a bird’s beak.
Lateral surfaces compressed, their junction constituting an obtuse median ridge.
There are no minor lateral prominences. ‘The surface is uniformly covered with
minute pustulate projections. At a‘distance of ‘3 inch from the apex, the crown
bifureates rectilinearly with an obtusely-rounded angle, forming two lateral exten-
sions of unequal length as stated above. The lateral extremities are thin, somewhat
angular, with a well defined ridge extending alongthe posterior surface. The shorter
one terminates in a projecting rounded boss: the longer in a backwardly-curved
obtusely-pointed extremity. Anterior surface thin, partly hidden by matrix.
Posterior surface, angular and deeply grooved vertically, as though by rubbing
against an opposing tooth. Lateral extremities below the bifurcation, are about ‘1
of an inch in thickness, being one-half the breadth. The basal portion of the tooth
is only visible in the centrally divided portion, and is not large.

Its nearest affinity seems to be with Helodus, but it differs from that genus so
materially in the pointed recurved character of the crown, in its pyramidally
acuminate form, and the deeply divided base, that it is extremely doubtful whether it
can have occupied an equivalent position to the teeth of Helodus. It also bears a
superficial resemblance to an American form from the St. Louis limestone which was
described by Dr. Leidy under the name of Chomatodus venustus (‘« Trans. Am. Phil.
Soc. Philadel.,” Vol. XI., pl. v., figs. 19-21). The species was afterwards included
in the genus Venustodus with the specific name Leidyi, by Messrs. St. John and
Worthen (“ Palzon. of IIl.,” Vol. VI., p. 350, pl. ix., figs. 1-4). The teeth included
under this definition are of two kinds, one presenting a similar angular form with
pointed crest, to those described above, the second form is smaller and only slightly
arched in outline. The first form only exhibits any relationship with the Armagh
specimen and it is very probable that itis merely accidental: Venustodus leidyi differs
from the tooth now described in having an acuminate apex to the crown without
curvature, in the lateral extensions of the crown being equal in length, and in the
lateral expansions being occupied by a variable number, between ten and eighteen,
of delicate, though well defined, denticulations : the crown is also encircled by a
continuous belt of coronal folds, and the base forms a relatively narrow plate, nearly
co-extensive with that of the crown.

Formation and locality : Mountain Limestone, Armagh.
Ez coll. Earl of Enniskillen.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 403

Genus—Lophodus, Rowanowsky.

Lophodus—H. Rowanowsky, 1864. ‘Bull. d. 1. Soc. Imp. des Nat. de Moscou,” p. 160.
Helodus (partim)—Agassiz, and others.

Teeth, generally much broader than long, median surface produced to form a
conical summit ; root compressed and regularly striated. The surface of the crown
is covered with enamel, finely punctate. The form is not ordinarily symmetrical ;
occasionally, irregularly contorted. The anterior basal margin is produced and
forms a sharp edge. The transverse section “exhibits the form of a nail with a
conical head.”

_ M.H. Rowanowsky describes the microscopical structure as being very uniform

in the different species, it is characterised by the union of the central medullary
canals, relatively large and irregular, giving rise to a number of smaller canals,
generally bifurcating, and radiating towards the surface where they are externally
visible as minute pores; all the canals branch into a large number of minute and
short, dentritic calciferous tubes.

The genus Lophodus was created by M. Rowanowsky for the reception of teeth
of fishes in which the crown of the tooth is more or less conical with a concavity
of the base which corresponds to the convex surface of the crown.

The root is deep but not thick. The teeth comprised in the genus Lophodus
were described by Prof. L. Agassiz as Helodus, and other authors to the present
time have followed, for the most part, his initiative. The species H. mammillaris
and H. didymus of Agassiz are referred to the new genus, whilst H. planus and H.
turgidus, Agass., are considered as the types of the old genus Helodus.

It is questionable to what extent the re-distribution of M. Rowanowsky may
prove correct. Helodus planus was considered by the late Prof. Agassiz, and is
now generally accepted as belonging to the same fish as Psephodus magnus.
And the somewhat miscellaneous group of Helodus turgidus has since been revised.
and amended. There is also the important discovery described by Messrs. Newberry
and Worthen, (‘Palzeont, Illinois,” Vol. II., p. 88.) of the teeth of Helodus and
Cochliodus keing found impacted together as to leave no doubt that they originally
belonged to the same fish. Some of the teeth so found, as for example, the one repre-
sented in pl. VL, fig. 4a, op. cit. bears a tolerably close resemblance to the typical
species of Lophodus figured by M. Rowanowsky. On the other hand, if the genus
be confined to teeth which have occupied a similar p»sition and have been arranged
in the same way as Orodus, or the recent Cestracion, there is every possibility that
it may prove a good and satisfactory genus.

Messrs. Newberry and Worthen instituted the same name in 1870 (“Survey of
Illinois,” Vol. IV., p. 360) to designate a genus of fossil fish which name has since
been transformed by Messrs. St. John and Worthen into Agassizodus (“ Paleeont.
Hines, “Vol, VE, p. 311).
''404 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

Lophodus leevissimus, Agassiz (sp.)

(PL Id, fies, 18, 18a, 13h, 18)

Psammodus levissimus—L. Agassiz, 1833. “ Poiss. Foss.,” Vol. IIL., pl. xiv., figs. 1-11.
4) : Sir. P. Egerton, 1837. “Catal. Foss. Fishes.”
Helodus : L. Agassiz, 1838. “ Poiss. Foss.,” Vol. TII., p. 104.
” ” J. E. Portlock, 1843. ‘Report on Londonderry, &ec.,” p. 461.
L. G. de Koninck, 1844. “Disc. des Anim. Foss. du terre Carb. de

Belg... p. 614, pl. .lw., fig..3; (pl. dit,
fig. 9, excluded).

af ib C. G. Giebel, 1848. “Fauna der Vorwelt,” Vol. I, pl. 3, p. 340.

a H. G. Bronn, 1848. ‘Nomencl. Paleont.,” p. 583.

_ 5 is 1849, “Enumerator Paleont.,” p. 647.

is 4s J. Morris, 1854. “Cat. Brit. Foss.,” p. 328.

‘ ss F. J. Pictet, 1854. “Traité de Paleont.,” Vol. IL, p. 267.

. ; F. Moy, 1855. “Brit. Paleoz. Foss.,” p. 630, pl. iii., fig. 17.

4 4 E. d’ Eichwald, 1860. “‘ Lethza rossica.,” Vol. I., p. 1546.

= J. Morris and Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. XVIII,
p- 100.

Young and Armstrong, 1871. “Trans. Geol. Soc. Glasgow,” Vol. III.,
p- 100, Supt. p. 72.
a e J. J. Bigsby, 1878. “Thesaurus Devonico.-Carb.,” p. 357.
Lophodus L. G. de Koninck, 1878. “Fauna du Calc. Carbonif. de la Belgique,”
p. 30, pl. iv. hg. 6.

Teeth, small ; transverse diameter equal to three times the antero-posterior one ;
crown elevated into a simple obtuse cone, of which the base occupies the centre of
the tooth ; the crown is gradually depressed and tapers from the central cone to
the extremities, which are feebly truncated. Surface uniformly punctate or smooth.
The root is slightly less in depth than the height of the crown and thinner, it is
directed obliquely forwards, and separated posteriorly from the crown by a small
groove. The inferior surface of the root is slightly concave. It is composed of a
coarsely striated, bony structure.

The specimens figured by Agassiz (“Rech, sur les Poiss. Foss,” Vol. HI,
pl. xiv., figs. 1-11) belong in all probability to this species, the remaining figures

do not.

Formation and locality: Mountain Limestone, Armagh.
Ex coll, Earl of Enniskillen.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 405

Lophodus gibberulus, Agassiz (sp.)
(PL LE, fies 19.)

Psammodus gibberulus—L. Agassiz, 1838, ‘Poiss. Foss.,” Vol. IIL, pl. xii, figs, 1, 2.
‘a ss P. de G. Egerton, 1837. “Cat. of Fossil Fishes.”
Helodus a L. Agassiz, 1838. “ Poiss. Foss.,” Vol. IIL., p. 106.
- P J. E. Portlock, 1843. “Geol. Rept. Londonderry, &c.,” p. 461.
ss 3 C. G. Giebel, 1848, “Fauna der Vorwelt,” Vol. I., pl. 3, p. 340.
a as H. G. Bronn, 1848. “Nomencl. Paleont.,” p. 583.
ts : i, 1849. ‘Enumerator Paleont.,” p. 647.
. ij J. Morris, 1854. “Cat. Brit. Foss.,” p. 328.
z 3 F. J. Pictet, 1854, “Traité de Paléont.,” Vol. II. p. 267.
a 5 E. d’ Eichwald, 1860. ‘Lethea rossica,” Vol. I. p. 1546.
3 o Morris and Roberts, 1862. “ Quart. Journ. Geol. Soc.,” Vol. XVIIL, p. 100.
“ ‘3 J. J. Bigsby, - 1878. “Thesaurus Devon.-Carb.,” p. 357.
Lophodus 5 ‘L. G. de Koninck, 1878. “Fauna du Oalc. Carbon. de la Belgique,”

p. 35. pl. iv., fig. 7.

Teeth, broadly elongated, crown elevated into two cones ; length °65 inch,
breadth -25 inch, height of central cone ‘25 inch, Crown; central cone obtusely
rounded, anteriorly depressed, longitudinal surface produced so as to form a
ridge like prominence. A deep sulcus separates the central cone from a smaller

one on the left side which partakes generally of the characters of the larger
elevation ; the lateral extremities of the coronal surface are obtuse, about the same
breadth as the base of the central cone, and are recurved upwards producing the
appearance of a small cone one on each side. Anterior surface slightly convex, and
one-third deeper than the posterior. Coronal surface enamelled, smooth along the
apex, deeply punctate elsewhere. Base large, extending laterally beyond the
surface of the crown; anteriorly it descends obliquely with the surface of the
crown, posteriorly it is deeply concave; roughly striated and fibrous; a ridge
extends along the anterior and posterior surfaces separating the crown from the
base, it is occasionally slightly serrated. Specimens found in the Limestone of
Belgium, and ascribed to this species by M. de Koninck, are stated to have both
lateral extremities with an equal number of secondary cones, in this respect
differing slightly from those described above.

The type specimen figured by M. Agassiz in the “ Poissons Fossiles” is slightly
imperfect at one extremity. It is from the Limestone of Bristol.

Formation and locality ; Mountain Limestone, Armagh ; Bristol ; Yorkshire.
Ez coll, Ear of Enniskillen.
''406 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

Lophodus mammillaris, Agass, (sp.)

(PI. LI, fig. 20.)

Helodus mammillaris—L. Agassiz, 1838. “ Poissons Fossiles,” Vol. 1II., pp. 173 and 383.
es % J. E. Portlock, ‘1845. “ Rept. Geol. Londonderry,” p- 461.
mn 5 C. G. Giebel, 1848. “Fauna der Vorwelt,” Vol. L., pt. 3, p. 341.
3 a H. G. Bronn, 1848. ‘Nomencl. Paleont.,” p. 583.
3 op a 1849. “ Enumerator Paleont.,” p. 647.
3 - J. Morris, 1854. “Oat. of Brit. Foss.,” p. 328.
5 : F. J. Pictet, 1854. “Traité de Paléont ,” Vol. IL., p. 267.
9 4) F. Moy, 1855. “Brit. Palwoz. Foss.,” p. 631, pl. 3 L., fig. 16.
5 _ Morris and Roberts, 1862. “ Quart. Journ. Geol. Soc.,” Vol. AV EET p. 100;
3 : Young & Armstrong, 1871. “ Trans. Geol. Soc. Glasgow,” Vol. ITT.,Supt., p.72.
” oD J. J. Bigsby, 1878. “Thesaurus Devon Carb.,” p. 357.
Lophodus __,; L. G. de Koninck, 1878. “Fauna du Cale. Carb.,” p. 35, pl. iv., figs. 9, 10,
1,

Teeth, “ crown very much elongated, narrow, abruptly pointed at each end,
having a moderately large, rounded, abruptly-tumid gibbosity, rather nearer to one
end than the other, and sometimes having an obscure bead-like projection, with an
underlying vertical area, over one of the long lateral margins ; short end even and
pointed ; long end with one or two very faint, small, secondary gibbosities. Surface
of the large prominent boss coarsely granulo-punctate, the punctations being finer,
and often obscured by a polished surface of ganoine on the ends. Average length
seven lines, greatest width two lines, height of crown one and a half lines.”—
(M‘Coy.)

M. de Koninck in describing this species gives as a characteristic distinguishing
it, the possession of two small pointed tuberosities, one in front of, and the other
behind, the basal portion of the median cone; these he regards as separating the
species fron. Lophodus gibberulus and L. (Orodus) subteres, which offer no trace of
such tubercles. Professor M‘Coy considers that this species may be found
eventually to belong to either one or other of the species named, or that the three
may be only one species. There appears no reason to doubt that M. de Koninck
is correct.

The specimens were named by Professor L. Agassiz, it being his intention to describe
them in a supplement. The latter unfortunately never appeared.

Formation and locality: Mountain Limestone, Bristol and Armagh.
Ex coll, Karl of Enniskillen.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 407

Lophodus didymus, Agass.
(Pl. LL, figs. 21, 21a.)

Helodus didymus—L. Agassiz, 1838. “ Poiss. Foss.,” Vol. III., pp. 173 and 383.
sy is J. E. Portlock, 1845. ‘Rept. Geol. of Londonderry,” p. 461.
s 3 C. G. Giebel, 1848. “Fauna der Vorwelt,” Vol. L, pt. 3. p. 341.
s “ H. G. Bronn, 1848. ‘Nomencl. Paleont.,” p. 583.
a FP 9 ’ 1849. ‘ Enumerator Paleont.,” p. 647.
f J. Morris, 1854. “Cat. Brit. Foss.,” p. 328.
a “ F. J. Pictet, 1854. ““Traité de Paléont.,” Vol. IT., p. 267.
ss - F. M‘Coy, 1855. “Brit. Palsoz. Foss.,” p. 630, pl 31, figs. 18, 19, 20.
- ‘3 Morris and Roberts, 1862. ‘ Quart. Journ. Geol. Soc.,” Vol. XVIIL, p. 100.
> - H. Rowanowsky, 1864. “Bull. Soc. Imp. des Nat. de Moscou,” p. 162, pl. iv.,
fig. 23.
5 + J.J. Bigsby, 1878. ‘Thesaurus Devonico-Carb.,” p. 357.

Teeth, “Crown of tooth usually much elevated in the middle into a very pro-
minent cone, more or less deeply notched at the apex, and having from that notch
a more or less distinct sulcus extending towards the base of the crown, the border
of which is elevated in the middle, particularly the posterior side close to, or
vertically over which, the double apices of the cone usually incline. Surface,
coarsely granulo-punctate, most so on the end of the middle cone, leaving the ends
of the tooth nearly smooth (the granules being closed and elevated in the unworn
tooth, but impressed punctate in old ones), width of average or rather small specimen
four lines, height two and a half lines, but sometimes more, and often less.”—
(M‘Coy.) The root is small, compressed and vertically striated.

Formation and locality : Mountain Limestone, Armagh.
Ez coll. Ear] of Enniskillen.

Lophodus reticulatus, Davis.
(Pi. Ul, se. 22.)

Teeth, transverse diameter 1°3 inches; antero-posterior diameter °3 of an inch
in the widest median portion. Crown generally depressed, produced to form a
median cone with a large secondary cone on each side and smaller intermediate
ones. Principal cone situated nearer one end than the other, obtusely pointed,
broader laterally than from front to back : a carina extends from central cone on
each side, from which rise the lateral ones similar in character to the median one ;
lateral terminations of crown truncate. Surface of cones, smooth, punctate ;
anterior and posterior surface expanded and depressed, reticulate ; posterior margin
produced and forming a thick and rounded ridge. Base, hidden by matrix.

The characters of the type specimen of this species are somewhat indeterminate.
Its surface possesses a median ridge with cones which ally it to Orodus, whilst the

TRANS, ROY. DUB. SOC., N.S., VOL. I. 3 T
''408 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

antero-posteriorly expanded base of the crown gives it a slightly Helodont character.
It may be found to occupy an intermediate position, at present it is included in the
genus Lophodus. :

Formation and locality : Carboniferous Limestone, Wensleydale, Yorkshire.
Ex coll. William Horne, Esq., Leyburn.

Lophodus serratus, Davis.
(Pl. LL, figs, 23, 24.)

Teeth, small, narrow; transverse diameter *6 of an inch, antero-posteror diameter
‘12 of an inch. Crown ascends from each lateral extremity to the central cone,
latter pointed and somewhat beak-like with a slight curvature posteriorly ; sub-
median ridge descends from the apex of the central cone, along each lateral pro-
longation from which spring eight small subconical tubercles on one side and ten
on the opposite one ; tubercles equidistant, and along with the central one uniformly
punctate. Anterior surface of crown, convex, smooth near the base. Posterior
surface concave, with a series of enamelled folds extending across the tooth parallel
with its margin.

This species is distinguished from Z. mammullaris (Ag.) to which it otherwise
bears considerable resemblance by the tuberculation of the median coronal ridge.

Formation and locality : Carboniferous Limestone, Wensleydale.
Ex coll. Wm. Horne, Esq., and Reed collection, York Museum.

Lophodus bifurcatus, Davis.
(Pl. LL, figs. 25, 25a.)

Teeth, small ; transverse diameter across base °5 of an inch ; height ‘4 of an inch.
Crown consists of large, obtusely subangular, obliquely inclined convex surface ;
with a greatly depressed, slightly twisted, prolongation of the lateral extensions
narrowing to subacute horizontal extremities. Anterior margin prominent ;
surface of crown slopes backwards to the posterior margin, which is much
elevated ; basal margin of crown projects beyond the roots. Surface uniformly
punctate. Root, short, extending to the termination of each lateral extension of
the crown, open porous structure.

This unique and peculiar tooth is provisionally placed in the genus Lophodus,
resembling in some important respects the teeth included in that genus, but the
peculiar anterior-posterior slope of the coronal surface and the deep lateral exten-
sions of the enamel somewhat approach the character of the genus Ramphodus,
but in this instance the lateral extensions are equal in length, those of Ramphodus
being unequal and the apex of the crown is not pointed as in that genus.

Formation and locality : Carboniferous Limestone, Wensleydale.
Ex coll. Wm. Horne, Esq., Leyburn.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Briton. 409

Lophodus levis, Davis.
(PL EE, Gos. 26, 27.)

Teeth, median or small, varying from ‘6 in transverse diameter and ‘2 inch antero-
posterior diameter to one-third that size. Crown, variable in form, raised to form
a sub-median cone; a ridge descends from the central cone on each side situated
on the posterior surface of the middle line; extremities subquadrate or very
obtusely rounded; crown surface enamelledand punctate ; anterior and posterior basal
margins of crown, prominent, forming a sinuous ridge, much elevated in centre.

Base short, less extensive than the crown, open porous structure.

This species is much wider from back to front than L. serratus, and the transverse
ridge is smooth and without serrations. An example is figured showing four teeth
in their natural position, which appear to belong to this species though they are not
quite so broad in proportion to the width as the larger specimen.

Formation and locality : Mountain Limestone, Richmond.
Ex coll. Reed collection, York Museum. William Horne, Esq., Wensleydale.

Lophodus sinuosus, Davis.
(PL ie. no, co)

Teeth, medium size ; crown, nearly an inch across, and '25 of an inch from front
to back, peculiar sigmoidal form, right lateral extremity sub-quadrate, depressed,
surface raised to form a single cone, about one-third the distance from the
extremity. Cone with broad, obtuse antero-posterior ridge ; left prolongation of
surface level, anterior and posterior margins slightly convergent for a distance
equal to the length of the right extremity, remaining portion extends at an angle
of 45° backwards and is rapidly acuminate. Surface smooth and punctate, without
lateral ridge. Base equal in depth to the height of the crown with the usual
characters.

This peculiarly shaped tooth, with others of similar but not exactly the same form,
appears to differ from any previously described. It is quite possible that some of
the forms now described as separate species may be discovered to be modifications
of only one or two, but until better specimens are cbtained it will be premature to
correlate them.

Formation and locality ; Mountain Limestone, Richmond, York.
Ex coll. Reed collection, York Museum,

61.2
''410 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

Genus—Diclitudus, Davis.

Teeth, small. Crown with two subequal prominent cones separated by a deeply
concave depression of the surface. Base of the crown conforming with the superior
surface. Root sinuously parallel and co-extensive with the base of the crown.

Diclitodus Sonia. Davis.
(PL i.,: figs. 29, 29a.)

Teeth, small. Crown consisting of two cones ; transverse diameter ‘3 of an inch,
height *2 of an inch. Cones, equal in size, separated by a circular hollow equal
in depth to the external lateral margins of the cones and about one-half the entire
height of the tooth. A ridge extends from each lateral extremity transversely
across the tooth, having slight indications, when magnified, of tubercles. The apex
of each cone is obtusely rounded, smooth and enamelled; surface uniformly
punctate; the basal margin of the crown is sinuous, conforming to its superior
outline, it consists of a prominent, slightly recurved ridge, separated by a sulcus
from the upper surface. Root, equal in depth to the height of the crown ; close,
fibrous structure, parallel with the sinuosity of the base of the crown and two
rows of deep regular punctures, with an intermediate ridge; attenuated below ;
under-surface similar in outline to the base of the crown.

Several examples of this peculiar tooth have been found in the Limestones of
Wensleydale along with some other unique forms. It appears to resemble in
structure the teeth of Orodus, but its double biconal arrangements separate it from
any other genus hitherto described.

Formation and locality : Carboniferous Limestone, Wensleydale, Yorkshire.
Ex coll. William Horne, Esq., Leyburn.

Group.—Cochhodontidee, Owen.
Cochliodontidee—R. Owen, 1867. ‘‘ Geological Magazine,” Vol. IV., p. 59.

A well defined group of fish-palates, with many characters in common, is
represented in the Carboniferous series of rocks almost exclusively. The central
genus of the group is Cochliodus, and branching with various modifications are the
genera Streblodus, Sandalodus, Deltodus, Psephodus, Deltoptychius, Peecilodus,
Xystrodus and Tomodus. Before proceeding to describe the peculiar characteristics
of this group, it may be woith while to briefly summarize the opinions, classificatory
or descriptive which have already been published. The remarks applied by the
late Proiessor Agassiz to the teeth of Placoid fish in general are especially true of
this group. After pointing out the imperfection of the actual knowledge of
cartilaginous fishes, he remarks that surprise should not be felt at the little
progress made in the study of the fossils pertaining to this group of animals. The
difficuities attending the determination of the teeth of sharks and rays, which are
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 411

frequently the only parts of the fish preserved, and which occur throughout nearly
all the strata in which fossils are found, is rendered very great, from the fact that
only in a very few instances can the determination be based on a comparison of the
fossil species with the existing ones. The species found in the more recent forma-
tions may be satisfactorily associated with living forms : but lower than the Tertiaries
the geological affinities of the fossil fishes become more and more a matter of
generalized speculation. The fishes of the secondary formations differ almost en-
tirely from those now existing, whilst in the still earlier primary rocks, the characters
exhibited by the fossils are only in rare cases comparable with living species, and in
no instance is this so apparent as in the group of palates now under consideration.

Professor Agassiz originally included in his genus Psammodus all the teeth of
Cestraciontes, of which the surface is neither wrinkled or reticulated, without crest,
or longitudinal or transverse ridges. The forms of the teeth included in this descrip-
tion were very various.* The genus comprehended all the species whose crown
was formed, as in Cestracion, of small vertical tubes opening on the surface and
extending downwards into the tooth in the form of medullary canals; thus defined

it included :—

Psammodus gibberulus. Psammodus contortus.
P, subteres. P. Icngidens.

P. linearis. _ P. reticulatus.

P. rugosus. , P, magnus.

P. porosus. P. tenuis.

The discovery of further specimens convinced M. Agassiz that several of the
palates regarded as species of Psammodus were of generic value. Their occurrence
in strata extending from the Stonefield slate and clays of Shotover through the
Permian and Coal Measures series to the Mountain Limestone, supported the
inference that during these long periods several types of Cestracions existed, which
whilst closely related in their dentition were sufficiently distinct to have constituted
separate genera.

The following modifications of the genus Psammodus were therefore adopted ;
without, however, being regarded either as final or more than approximately

Correct: =:
Helodus (Psammodus) gibberulus and subteres, &c.
Chomatodus a linearis, &c.
Psammodus 3 rugosus, porosus.
Cochliodus 4 contortus.
Strophodus 55 longidens, reticulatus, magnus, tenuis, &c.

The genera Ceratodus, Ctenodus, Acrodus and Ptychodus were also associated with
the above, being regarded as more nearly related to the Cestracionts than to the Rays.

* 6 Poiss. Foss.,” Vol. IIL, p. 103.
''412 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

The two genera, Ceratodus and Ctenodus, were correctly regarded as materially
differing from the dentition of Cestracion, each tooth occupying a ramus of the
upper or lower jaw respectively ; those of each jaw being attached to each other at
the median line.

After a consideration of the microscopical structure of the teeth, they are divided
into three groups. The first, comprehending the genera Ptychodus, Strophodus and
Acrodus, of which the existing Cestracion may be taken as the type; it is distin-
guished by an outer layer of enamel on the dentine forming the surface of the
crown. The second group is composed of the genera Chomatodus, Cochliodus,
Psammodus, and Ceratodus, and in this the layer of enamel is absent, and the
medullary canals open on the surface of the tooth. The third group is formed of
the two genera Ctenodus and Ctenoptychius ; they are characterized by the posses-
sion of an almost homogeneous surface of dentine which only exhibits occasional
traces of the medullary canals or tubes. Not having a tooth of Helodus at his
disposal, Agassiz was unable to assign its position but considered it would probably
fall into the second group. |

Prof. Owen (“Odontography,” p. 49, et seq.) accepts the classification of Agassiz,
and regards the existing Cestracion of the Australian seas as the only existing
representative of the fossil genera indicated by that ichthyologist. Hybodus, Orodus
and Petalodus are also included in the family. Prof. Owen disagrees with Prof.
Agassiz as to the microscopical structure of the teeth and contends that the
medullary tubes have no relation to the punctate impressions of the enamelled
surface. The “tubes always terminate at a short distance from the surface of the
tooth, either by anastomosis or by sub-division into other tubes of such extreme
minuteness that the combined diameters of five hundred of them would barely equal
the breadth of a single superficial punctation. These impressions on the teeth of
Psammodi, like the transverse ridges of those of the Ptychodi, are consequences
of the conformation of the original matrix, and can be regarded only as adaptations
conformable with the habits and food of the extinct species; and as they are not
due to a certain tubular structure, so neither can they be viewed as evidence of
such structure when it has not otherwise been proved to exist.”

With regard to the extinct genus Cochliodus, Prof. Owen remarks that it presents
avery interesting modification, resembling in structure those of Psammodus. Here
the jaws are paved with teeth arranged in a few oblique contorted series, as in the
Cestracion, but a single tooth occupies the space covered by an entire row in the
existing Australian genus. In the specimen figured (“Odontography,” pl. 222, fig. 1.)
there are three of these large contorted dental plates in each ramus of the jaw.
‘The microscopic structure of these large teeth closely resembles that of the true
Psammodus; the medullary canals have the same straight, sub-parallel course, and
sparing dichotomous sub-divisions, but they are relatively wider, and are separated
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 418

by interspaces of less breadth. The calcigerous tubes are also wider at their origin ;
they come off not quite at right angles to the medullary canal, but are slightly
inclined to the grinding surface of the tooth ; they quickly ramify, sending off their
branches at nearly right angles, and are less flexuous in their course than in the
Petalodus ; they dilate into angular cells at many parts of the mid-space between
the medullary canals.”

Moy (“British Paleozoic Rocks and Fossils,” p. 621) differs from Profs.
Agassiz and Owen, and considers that there can be no real affinity between the
genus Cochliodus and Cestracion or any of the Sharks ; for, first, the teeth are
supported on a strong bony jaw as in Placodus (which also agrees in having three
teeth on each side of the lower jaw, although differing in microscopic structure) ;
secondly, the enrollment of the teeth is on the outside of the jaw, and not as in
sharks, on the inside to allow the succession of teeth from behind forwards ; and
finally, a broken tooth of another species, the C. oblongus, enables me to prove
the succession of the teeth was not by revolution from behind, as in the Plagio-
stomous fishes, but vertically from below upwards, as in the Pycnodonts (op. cit.,
pl. 3H, fig. 19 and 31, figs. 28.) Prof. M‘Coy describes four genera, in addition
to C. contortus, described by Agassiz in the “ Poissons Fossiles,” viz., C. acutus,
C. magnus, C. oblongus, and C. striatus. These had been previously named by
Agassiz, but not described (“ Poiss. Foss.,” Vol. IIL, p. 174). The type specimens
are in the Enniskillen collection. .

The genus Pecilodus, also instituted by Agassiz, was considered by M‘Coy to
be only a sub-genus of Cochliodus. The number and form of the teeth, with the
strong inrollment, particularly of the median tooth over the outer part of the jaws
seeming to be the same in both, “the only tangible difference of the present teeth
being the more or less distinct longitudinal ridges which cross the teeth parallel to
the inner margin.” In addition to Pecilodus jones and P. transversus, P. obliquus,
P. parallelus, and P. sublevis, named by Agassiz (“ Poiss. Foss.,” Vol. IIL, p. 174),
M‘Coy described two others, P. aliformis and P. foveolatus.

In the year 1858, Prof. Agassiz was led to reconsider and revise his classification
and arrangement of the Cochliodont group of palates. Since the publication of
bis great work on fossil fishes, in 1840-3, an immense number of specimens had
been discovered, and it was, in consequence, possible to form a much clearer con-
ception of the actual characters and relationships of the several groups forming the
entire fish-fauna of the Mountain Limestone. The forms, at first considered as
species of Cochliodus, were not only found to be persistent, but developed
characters, shewn in largely increased numbers of specimens, which proved their
several peculiarities to be of generic importance. The result was, that M. Agassiz
divided Cochliodus and Poscilodus into the genera tabulated in the following list,
and intended to redescribe the whole group. Adverse circumstances intervened,
''414 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

and his premature death finally prevented all chance of the work being completed
by his master mind and hand :—

Cochliodus contortus = Cochliodus contortus.
C. magnus = Psephodus magnus.
C. oblongus = Streblodus oblongus.
C. acutus = Deltoptychius acutus.
C. striatus = Xystrodus striatus.
Peecilodus angustus = X. angustus.

- a. j Peecilodus jonesii.

P. obliquus = P. obliquus.

P. subleevis

P. parallelus

= Deltodus sublevis.

With the addition of other species, the arrangement in the second column will
be adhered to in the following pages.

In 1867, Prof. Owen published a paper in the “Geological Magazine” (VolTV.;—p.
59) on the mandible and mandibular teeth of Cochliodonts, in which he considers
“that ihe extinct crushing sharks of the Mountain Limestone period, though
instructively represented by a lingering member of a once numerous section of
Chondropteri, must be relegated to a distinct though conterminous family, for which
I proposed the name of Cochliodontide, from what may be regarded as the repre-
sentative genus, Cochliodus, Ag.” Specimens of the mandibles and teeth of
Cochliodus contortus, Ag., (including Tomodus convexus, as described by Owen) and
Streblodus oblongus, Ag., are described, with the result that Prof. Owen considers
that the relative positions of the teeth of each ramus of the jaw with its symphysis
corresponds with the parts of the mandibular rami of Cestracion containing the
anterior crushing teeth, and that they afford no ground for assuming that the sym-
physis was prolonged, as in Cestracion, for the support of conical or any other
teeth. The mandible increases in depth posteriorly but diminishes in breadth, indi-
cating a shape of jaw like that in Cestracion. The structure of the bone resembles
that of the better ossified parts of the chondrine of plagiostomous fishes. Tn another
example in the Woodwardian Museum, Cambridge, the reverse of the above is seen,
in which the posterior end of the right ramus of the mandible is of little breadth
and depth, but it gains in both, and chiefly in the latter dimension, as it approaches
the symphysis, and there rapidly acquires great breadth and thickness. From the
oppositeness of these descriptions it may be inferred that the soft cartilaginous sup-
ports of the teeth, during fossilization have been more or less subjected to pressure
or other circumstances which have modified the form of the jaw, but at the same
time the important fact is deduced that the teeth of Cochliodonts consisted of teeth
whose convolutions were attached to, and partially embedded in a thick cartilaginous
''On the Fossil Fishes of the Carboniferous Limestone Serves of Great Britain. 415

mandible, a part of which extended inwards from the jaws and formed a covering or
base for the palates which may or may not have had other teeth attached. None -
of the present specimens exhibit any trace of other teeth having keen so attached,
and though examples have been discovered by American paleontologists in which the
teeth of Cochliodus and a species of Helodus have been found associated in such a
manner as to lead to the inference that they belonged to the same fish, this evi-
dence has not hitherto been confirmed by any British species.

As already stated, Dr. Giinther (“Study of Fishes,” p. 329), places the
Cochliodonts in his family Cestraciontide, along with Ctenoptychius from the
Devonian; Psammodus, Chomatodus, Petrodus, Polyrhizodus, &c., from the Carboni-
ferous series; and Strophodus, Acrodus, Thecodus and Ptychodus, from the Trias
and Chalk.

Having in the foregoing brief resumé glanced at the classification of the group
of fishes represented by the fossil Cochliodus adopted by the several authors enu-
merated, it is proposed to describe, in such detail as may be necessary, the dentition
of the members of the group which it is possible satisfactorily to interpret. The
elucidation of the subject is, however, attended with many difficulties, and it is only
tentatively that the attempt is now made: the complete reconstruction, on a
thoroughly sound basis, of the dentition of this large and important group of fishes
must depend in a very great measure on the acquisition of more perfect specimens.
Much information can be gathered from the study of the unique collection of this
group collected by Lord Enniskillen, and considerable light has been thrown on the
genus Cochliodus by some magnificent specimens gathered by American paleeonto-
logists from the Carboniferous Measures so largely developed in Illinois and Ohio,
but the complete and perfect dentition of any single fish has not yet been discovered
in a state sufficiently well and regularly preserved to warrant the statement that it
is perfectly known and consequently comparable or otherwise with that of existing
fishes.

The teeth of the group of fish remains, for which Prof. Owen has proposed the
name Cochliodontide, differ much in the details of their form and arrangement,
but they passess the chief character in common, which is the distinguishing feature
of the group, viz :—that they grow or increase in size, not as in most fishes, by the
old and worn teeth being replaced from behind or below, but by continuous or
repeated additions to the inner or posterior margin of the surface of the tooth, so
that the same tooth is always increasing in size with the growth of the fish, and
assumes an inrolled or convoluted form. An analogue of this peculiar growth is
seen in that of the testaceous covering of the mollusca, which, though it assumes a
wonderful variety of forms increases in size by the addition of repeated layers to
the open margin of the shell. A transverse section of the teeth of Cochliodus,
Streblodus, Deltodus or Deltoptychius, exhibits a more or less helecine involution,
whilst those of Psephodus, Peecilodus or Xystrodus, though flatter, increase by the

radial expansion of the triturating surface.
TRANS, ROY. DUB, SOC., N.S., VOL, I. es
''416 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

The dentition of the genera Cochliodus and Streblodus appears to have been very
similar, consisting ofa series of three deeply inrolled teeth on the ramus of each jaw.
The jaws were cartilaginous though it is probable that the cartilaginous substance
was to some extent permeated by minute grains of ossified matter, similar to the
chondroid bony structure of some of.the plagiostomous fishes. The specimens
described by Prof. Owen, already referred to, and those to be described in further
pages of this work, do not indicate that other teeth occupied the intermediate space
between the two lateral series covering the rami of the jaws. Messrs. Newberry
and Worthen have, however, described specimens from the Keokuk limestone of
Illinois (“Paleeont. Illinois,” Vol. IT., p. 89.) from which it appears that the fish had,
in addition to convoluted teeth of similar form to Cochliodus, a number of smaller
teeth resembling, if not identical with, those of the genus Helodus.

The dentition of Psephodus magnus, Ag., differs considerably from that of Cochliodus
or Streblodus. The teeth are much flatter and exhibit a very slight curvature,
especially in the larger teeth. Combined with great variety in outline and form,
there is a general similarity in the superficial appearance of the teeth as well as in
the denticulation of the margins. The examination of the magnificent suite of
specimens in Lord Enniskillen’s collection has suggested the following deductions as
to the arrangement of the dentition of this genus.

Many of the teeth are smoothly concave on the under surface, presenting the
appearance reproduced in Pl. LV., fig. 1; the concavity is in the direction of the
line of growth, expanding in the usual manner from a comparatively narrow base
to a widely expanded opposite margin. In Psephodus it will be observed that the
teeth appear to have increased in size along the margin which enveloped the outer
side of the jaw. The posterior edge of the largest tooth of the set is more or less
rounded ; the anterior edge is comparatively straight and fits to the second or
median tooth. The concavity or channel is wider at the rounded extremity of the
tooth and gradually diminishes towards the straight anterior margin. The next
or median tooth in the series exhibits similar characters, the channel still continues
to diminish in diameter, being at the widest part equal to the narrowest of the
previous tooth, and the convolution extending from the inside to the outside of the
jaw. The third tooth was situated between the median one and the symphysis of
the two rami of the jaws, it converges rapidly in diameter towards the symphysis,
and the channel on the underside becomes attenuated almost to a point. In front of
this there is a long narrow tooth (PI. LV., fig. 6.) whose surface is raised in the form
of several obtusely pointed cones. There is no indication that similar narrow teeth
were attached to either the median or large posterior teeth and it seems probable
that they were attached in front of the anterior pair of teeth, which are comparatively
narrow, for the purpose of seizing the objects on which the fishes fed with greater
firmness and security. In addition to the long and narrow tooth on the external
margin of the anterior one, there were others which were ranged from its internal
''On the Fossil Fishes of the Carboniferous Limestone Serics of Great Brita. 417

surface backwards into the mouth. A series of three of these is represented in
PL LV., fig. 4. They probably, judging from their form and arrangement, occupied
the space between the median line of the palate and the large teeth arranged on each
ramus of the jaw. Whether the teeth were similarly arranged in both jaws it is
impossible to say, but it appears probable that they were; the only difference
observed in the teeth being in the disposition of the coronal surface ; in some
specimens the crown is worn by attrition quite hollow, whilst in others it is rounded
and convex though evidently much used.

The above observations may perhaps be summarized as follows: that a row of
three principal teeth increasing in size backwards were attached to each cartilaginous
ramus of the jaw; that the diameter of the jaw, as indicated by the groove
or channel on the under-surface of the teeth, diminished towards the symphysis ;
that a long, narrow tooth was placed in front of the anterior one, and that a series
of at least three Helodoid teeth were placed behind it, extending over the palate and
increasing in size backwards.

The dentition of Deltodus, Deltoptychius, Peecilodus, and the remaining genera
were arranged, with varying modifications to suit their several forms, in ap-
proximately close relationship to those already mentioned. The form of the teeth
in the upper and lower jaws respectively in Deltoptychius and Deltodus somewhat
resemble each other in general characters but are altogether distinct in detail.
The teeth of Deltoptychius acutus were probably arranged very similarly to those
of Cochliodus, being closely related in form so far as the teeth of the lower jaw are
concerned. The teeth of both the upper and lower jaws are hollowed on the
inferior surface and show the direction in which they were attached to the jaws.
The teeth of Deltodus and Deltoptychius here ascribed to the upper jaw, appear
to have had only one tooth to each ramus of the jaw, in this respect being similar to
Ceratodus. It is possible that both jaws of Pcecilodus were furnished in a similar
way.

It is interesting to note that Professor Agassiz (“ Poiss. Foss.,” Vol. II., p. 113),
speaking of the genus Cochliodus, describes a jaw with the teeth attached in their
proper places. The specimen was formerly in the collection of Captain Jones, and
is now in that of the Earl of Enniskillen by whom it was placed at the disposal of
Professor Agassiz; it is represented in pl. 19, fig. 14, of the “ Poissons Fossiles,”
and is regarded as being “of the greatest importance tothe history of the Cestracionts
of the older formations, for not only does it serve to solve all doubts on the subject
of Psammodus, but I have acquired, in seeing it, the confirmation of the supposition
I had formed on the subject of the genus Ceratodus, which I have always believed
should be regarded asa Squalus, having only a single large dental plate, instead of
several ranges of teeth upon each branch of the jaw. The fragment in question
not only supports this opinion, but it constitutes a type intermediate between

Ceratodus and the Cestraciontes, living and fossil.” The new genus Cochliodus
3U8
''418 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britaw.

“in place of having a great number of rows of teeth placed the one behind the
other, in the form of large plaques more or less arched, as in the genera Acrodus
and Phychodus, or in the form of a cushion of twisted spindles, as in the genus
Cestracion, exhibits only a small number of teeth disposed in such a manner as to
cover a large portion of the rounded surface of the dentary border of the jaw.” The
fragment referred to exhibits a range of three teeth on each; it has, however, the
appearance of having had a fourth, which is lost. Professor Agassiz further
considers it evident that the small number of teeth preserved in Cochliodus, take
an intermediate place between the numerous ranges of teeth which form the fusiform
palates of the genus Cestracion, and that of Ceratodus with its four teeth, one to
each ramus of the jaw, and that their large contorted surfaces embraced a large
space upon the jaw.

The relationship surmised by Professor Agassiz to exist between Ceratodus and
Cochliodus may possibly prove correct, but the discovery of an existing species
of Ceratodus in the Australian rivers by Dr. Krefft, in 1870, has proved that
should such relationship be found between the two, Ceratodus will not join
Cochliodus as one of a family of sharks, but that the opinions hitherto held
respecting the Selachian attributes of the Cochliodonts will have to be seriously
modified. There are some points of resemblance between the Cochliodonts and Cer-
atodus which it may be useful to point out. The skull of Ceratodus is primarily
composed of cartilage, with a few ossified centres. The vertebral column is
notochordal. The pectoral arch mainly cartilaginous, and the pelvic arch entirely
so. Twenty-seven pairs of bony ribs. The mandibles are connected with the skull
by a suspensorium, they are short, with a wide symphysis. The disposition of the
teeth of Ceratodus is ascertained to be as follows :—“ An osseous palato-pterygoid
arch supports two palatal dental plates, whose horns or denticles project outwards,
the larger and more prominent being anterior. In advance of these are two cutting
teeth imbedded in the vomerine (mesethmoid) cartilage. The mandible supports a
similar pair of dental plates. These are attached by their inner edges to the
splenial bone, which invests the inner side of the jaw, while on the outer side they
overlie the cartilaginous centre of the ramus, and to some extent the angular bone,
with which they have a fibrous connection. In biting, the ridges of the dental
plates interlock, though the opposed surfaces are not so accurately adjusted as
altogether to prevent a sliding movement ; the vomerine teeth are unopposed. All
the dental plates are anchylosed to the supporting bones,” (L. C. Miall, “ Sirenoid
and Crossopterygian Ganoids,” p. 20, Paleeont. Soc., 1878).

With the present knowledge of the Cochliodonts it appears probable that the
dentition of some of the genera consisted of a single dental plate to each ramus of
the jaws, and though the palate and mandibles were cartilaginous with partial
ossification, the teeth were firmly implanted if not anchylosed. The dental plates
in Ceratodus rise into external folds or ridges, the surface of the investing dentine
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain, 419

being punctate, with minute tabular structure. The surface of the Cochliodonts is
similarly punctate and tabular in structure, and with modification it rises into
external folds and ridges. So far as known, the entire skeleton of Cochliodus was
more or less cartilaginous, and except in rare instances, where a portion of the
mandible has been preserved, the skeleton of this group remains unknown and
unpreserved.

Professor Miall (op. cit., p. 26,) discusses the probable mode of growth of the
teeth of Ceratodus, and enislinied that “it is probable that the tooth was at first
comparatively soft and vascular, that it grew, replaced the loss from wear, and
changed its figure as requisite, becoming fully calcified and rigid only in the adult.”
After careful comparison of the teeth of Ceratodus with those of the Cochliodonts, it

will be found that the teeth of the former resemble the latter to this extent, that
the several ridges or denticulations radiate more or less from a central point on
the smooth hinder surface of the tooth to its anterior or outside margin. It has
already been shown that the teeth of Cochliodus increase in size by the growth
or addition of new dental substance to the constantly expanding inner surface of
the tooth, giving it a convoluted form. In some other members of the group,
as in Psephodus, &c., a similar plan of growth results in a radial expansion of the
surface, wh'lst, at the same time, it maintains a depressed and flattened surface.
It is possible that the outer denticulated margin of Ceratodus increased in the same
way, the teeth increasing in size with the growth of the jaws to which they were
attached. The method of growth here indicated, though matter of speculation, is
perhaps more in consonance with observed facts, than the idea suggested that the
teeth remained in a soft state until mature. The observation made by Professor
Miall, that the posterior portion of the teeth would be much worn, and that lines
showing the repeated additions to the surface should be apparent, is not of great
value. It may be seen in a number of any of the genera of the Cochliodonts, that
in.most specimens the lines indicating growth are worn off, whilst in other
specimens they are distinctly visible, parallel with the margin of the newer portion
of the tooth. In the case.of Ceratodus, the tooth being more than usually flat,
and the new surface immediately exposed to the triturating action of the opposing
tooth, it will easily be conceived that the lines, if any, might be removed. With
regard to the first portion of the objection, the posterior or angular portion of the
teeth of Ceratodus are usually smooth, without ridges, and apparently considerably
worn.

The Cochliodonts, usually regarded and described as closely related to the
Cestracionts, with very great modifications of the dentary arrangement, have been
found to differ from that group in the following particulars. The jaws are joined
in front with a wide symphysial space, probably edentate. In Cestracion the anterior
portion of the jaws is greatly produced, and is armed with a median row of sharp
cutting teeth, with several others ranged on each side; the difference in the
''420 On the Fossil Fishes of the Carboniferous Limestone Series of Great Brita.

dentition of the two groups no doubt indicates a difference in the food of the fishes.
The sharp teeth in front and the crushing teeth behind, are well adapted for seizing
and crushing hard-shelled animals, such as crustaceans or molluscs, which probably
served as their food, whilst that of the Cochliodonts, from the flat or rounded
dentition, without, so far as is known, any sharp teeth for seizing animals of any
kind, leads to the inference that they were in the main, vegetable feeders.

It has been already shown that the teeth of Orodus, Agassizodus, and other
allied genera bear a very close resemblance to the existing Cestracion, only diverg-
ing in one or two minor points. These forms, found along with the Cochliodonts
in the Mountain Limestone, are so completely separated by their difference in form,
arrangement, and adaptations to the feeding of the fish, that they afford strong
evidence against their being members of the same group. The teeth of the living
Cestracion and those of the fossil Agassizodus, &c., are arranged on the rami of the
jaws without any intermediate palates or teeth; the dental arrangements of
Cochliodus, of Psephodus, and doubtless of others, combines the lateral teeth
enveloping the jaws along with other teeth which extend across the entire palate,
and the gape was without doubt much wider in the latter group. These differences
serve to separate the Cochliodonts from the Cestraciont sharks, whilst at the same
time, it cannot be denied, as indicated by Professor Agassiz, that there isa somewhat
close relationship between the dentary apparatus of this group and that of the
Ceratodi.

 

Genus—Cochliodus, L. Agassiz, 1838.
Syn. Psammodus, (pars.) 1833. L. Agassiz.

Teeth, medium size, two or perhaps three teeth to each ramus of the jaw,
remarkable for their enrolled and twisted form and the obtuse angle formed by
the rami of the jaws in front. Anterior teeth small, triangular, deeply convoluted ;
posterior teeth larger, more or less oblong in outline, with three ridges arranged
radially from the inside of the tooth outwards, surface smooth, finely punctate
Base : concave, osseous, smooth.
''On the Fossil Fishes of the Curboniferous Limestone Series of Great Britain, 421

Cochliodus contortus, Agass.

(Pl. LIL, figs. 1-6)

Psammodus contortus—L. A gassiz, 1833. “ Rech. sur les Poiss. Foss. ” Vol. IIT., pl. xiv.,
figs. 16-33, and pl. xix., fig. 14.
ee z Sir P. Egerton, 1837. “Cat. of Foss. Fish.”
Cochliodus, L. Agassiz, 1838. “ Poiss. Foss.” Vol. IIL, p. 115.
ra a R. Owen, 1840. “ Odontography,” Vol. II., p. 10, pl. xxii., fig. 1.
3 : J. E. Portlock, 1843. “Rept. on Geol. Fermanagh, &c.,” p. 466.
ss - H. B. Geinitz, 1845. “ Versteinerungsk,” p. 165.
. .. C. G. Giebel, 1848. “ Fauna der Vorwelt,” Vol. L., pt. iii., p. 336.
iy ~ H. G. Bronn, 1848. ‘“Nomencl. Paleont.,” p. 317.

” ” ” 1849. ‘Enumerator Paleont.,” p. 647.
F. A. Quenstedt, 1852. ‘ Hanb. der Petrefaktenk. p. 188.

- ‘ij J. Morris, 1854. ‘Cat Brit. Foss.,” p. 322.

‘ : F. J. Pictet, 1854. “Traité de Paléont.,” Vol. II., p. 267, pl. 33., fig. 31.

e ie F. M‘Coy, 1855. ‘Brit. Paleeoz. Foss.,” p. 622.

: F. Roemer, 1856. “In. Bronn Lethea geogn.,” Vol. I., p. 708,
pl. ixd., fig. 4.

5 5 F. d’Eichwald, 1860. “ Letheea. rossica.,” Vol. I., p. 1547.

Morris and Roberts, 1862. “ Quart. Jour. Geol. Soc.,” Vol: XVIIL., p. 100.
H. Rowanowsky, 1864. “ Bull.d.1. Soc. Imp. des. Nat. de Moscou., p. 159
pl. iii., figs. 7-10.

. . R. Owen, 1867. “Geological Magazine, Vol. IV., p. 59.
3 3 Enniskillen, 1869. ‘Cat. of Type Spec. Foss. Fishes,” p. 4.
i ss Young & Armstrong, 1871. “ Trans. Geol. Soc., Glas.,” Vol. III., Spt., p. 70.
a a H. A. Nicholson, 1872. “Man. of Paleont.,” p. 339, fig. 297.
< a F. Roemer, 1876. ‘‘ Lethea Paleoz. Atlas,” pl. xlviii., fig. 5.
a Armstrong, Young,
& Robertson, 1870: “Cat, W. Secor, Foss, p68.
5 S J.J. Bigsby, 1878. “Thesaurus Devonio.-Carb.,” p. 349.
5 e L. G. de Koninck, 1878. “Fauna du Cale. Carb. de la Belgiqne.,” p. 57,

pl. vi., fig. 14.

Teeth, sides of jaw and lateral rows of teeth converging at an angle of about 60°.
Posterior tooth oblong, obliquely truncated on the outer side of the posterior end to
form the posterior point; posterior edge rather abraptly raised to form the posterior
oblique ridge behind, sloping into a rather deep oblique hollow, which defines
the middle oblique ridge, which is much the most prominent and strongly rounded
of the three ; anterior ridge coinciding with the anterior margin, very slightly raised,
little tumid, separated by a moderate concavity from the steeply rounded side of
the middle ridge, and forming an angle of &0° with the outer margin. Second tooth
narrow, its posterior half very convex, forming a prominent, rounded ridge, rising
abruptly from the posterior margin, but sloping sigmoidally to the anterior margin,
which is not again relieved. Anterior teeth unknown, surface either smooth or
''4292 On'the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

fine granulo-punctate by the opening of the medullary glands, average length
of posterior tooth, one inch five lines, greatest width eight lines, width of middle
tooth five lines.”—-(M‘Coy.)

The Enniskillen collection is extremely rich in the number and beauty of the
specimens of Cochliodus contortus. Two specimens exhibit the teeth of the right
and left ramus of one jaw in natural position. They are represented on Pl. LIL,
figs. 1,2. Figure 2 a, represents the posterior tooth and 2 b the second tooth, of Prof.
M‘Coy’s description. The anterior teeth still remain unknown. A very careful
examination of the specimens of single teeth as well as the more perfect ones alluded
to above, and a pair of teeth in the Jones’ Collection at the Geological Society of
London, has failed to show any trace of teeth anterior to those shown in the figures,
nevertheless the anterior margins of the second teeth of M‘Coy appear to end ab-
ruptly and incompletely, and until more conclusive evidence be obtained, it may be
better to withhold any opinion as to their occurrence or otherwise. The cartilaginous
mass of the jaw supporting the teeth is preserved in some specimens, (see Pl. LIL,
figs. 1 and 6). In Pl. LII., fig. 1 it extends vertically parallel with the inside of the
jaw, and is about an inch in thickness. PI. LIL, fig. 6 represents a smaller tooth,
and in this case also it will be seen that the jaw extends considerably beyond the
outer or inrolled margin of the teeth and is expanded into a broad, thin, plate-like
mass in which the teeth are embedded.

Prof. M‘Coy has. asserted that teeth of Cochliodus (Streblodus) oblongus, Ag.,
have a “‘vertical:mode of succession, the young one being distinctly visible beneath
the level of the old one (‘ Brit. Paleeoz. Foss.,” p. 623, pl. 3 L., fig. 28, and pl. 3 H.,
fig. 19) from a transverse fracture” ; “the fractured edge shows the inrollment
of the outer margin of the tooth, and the whole thickness of its substance, showing
the vertically tubular structure of the superficial half, and the two dense layers
which form its concave under or dorsal surface. At about the thickness of the
substance of the old tooth lower down is seen the young tooth, exactly concentric
to it in outline and having its structure similarly displayed in the section.” Speci-
mens occur in the collection of Lord Enniskillen, which were prepared by the late
Mr. Crawford, his lordship’s assistant in the museum, with great delicacy and care ;
and these exhibit with perfect clearness the manner in which the teeth of the Coch-
liodonts grew or increased in size. Pl. LIL, figures 4 and 6 represent respectively the
larger and smaller teeth, from which it will be seen that the teeth on their initiatory
stages were very small, and that they constantly and persistently increased in size
by the addition of dentigerous matter to the inner margin of the dental surface,
causing the helicine form of the section and the convoluted contortion of the surface
of the tooth. As the growth of the tooth increased its size, doubtless corresponding
with the growth of the fish, the earlier or outside convolutions became embedded
in the cartilaginous mass of the jaw. It is an internal convolution of this kind
which, having become detached from the main mass of the tooth, deceived Prof.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 423

M‘Coy. An examination of the specimen in the Woodwardian Museum at Cam-
bridge has shown this to be the case, and also that the figures of the specimen given
in the “ British Palzozoic Fossils” are not exactly correct. The illustrations given
above are from two specimens of C. contortus, Ag. There are others equally well
prepared of Streblodus oblongus, Ag., which prove quite as conclusively that the
teeth of Streblodus were developed in the same manner as those of Cochliodus.

The “Geological Magazine” (Vol. IV., p. 59) contains the description of a man-
dible of a Cochliodont by Prof. Owen. It is from the Mountain Limestone of Bristol.
« Apparently the whole of the dentary part of the right ramus and the anterior halt
of that of the left ramus are here shown (op. ci. pl. u1., fig. 2). The posterior end
of the right dentary is of little breadth and depth, but it gains in both, and chiefly
in the latter dimensions, as it approaches the symphysis, and there rapidly acquires
great breadth and thickness. The lower border is thick and rounded, the outer
side moderately convex ; the inner side, somewhat wavy, being concave lengthwise
at its middle part. The hind part of the symphysis extends back like a shelf, from
below the dentigerous surface of that part of the mandible.” This specimen is re-
ferred to the genus Tomodus of Agassiz, but a comparison of the specimen with the
type specimens of that genus in the Enniskillen collection is at once conclusive that
the one described by Prof. Owen is not a Tomodus but in all probability a crushed
specimen of Cochliodus contortus, Agass., to which it certainly bears a close
resemblance.

Formation and locality : Mountain Limestone, Bristol.
Ex coll. Enniskillen collection ; Bristol and Woodwardian Museum.

Genus Streblodus, Agass. MSS., 1858.
Syn. Cochliodus—L. Agassiz, 1838. “ Poiss. Foss.,” Vol. III., p. 174.

Teeth, medium or small size, three teeth to each ramus of the jaw. Anterior
tooth, small, convex, sub-triangular in outline: median _ tooth, larger, sub-
quadrate, highly convex, margins connecting it with anterior and posterior
teeth, straight, inclined at a slight angle to the longitudinal axis of the tooth.
Posterior tooth, large, convoluted anteriorly and extending and expanding in
diameter backwards or inwards. Crown of posterior tooth characterized by a series
of two or three ridges with intermediate hollows extending radially from the anterior
margin. Third or posterior ridge covers about one-half the surface of the crown.
Coronal surface enamelled, punctate.

TRANS. ROY. DUB. SOG., N.S., VOL. I. 3x
''424 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

Streblodus oblongus, Agass. (MSS.)
(Pl. LIIT., figs. i-4.)

Cochliodus oblongus—L. A gassiz, 1838. ‘Rech. sur les Poiss. Foss.,” Vol. III., p. 174, indet.
Bs 5 J. E. Portlock, 1843. “Rept. on Geol. Londonderry, &c.,” p. 466, pl.
xiva, figs. 5, 10.

i 5 C. G. Giebel, 1848. ‘ Fauna der Vorwelt,” Vol. I., part iii., p. 336.

5 e H. G. Bronn, 1848. “ Nomencl. Paleont.,” p. 317.

} 53 H. G. Bronn, 1849. “ Enumerator Paleont.,” p. 647.

33 ys J. Morris, 1854, “Cat. Brit. Foss.,” p. 322.

ys o F, J. Pictet, 1854. “ Traité de Paléont.,” Vol. II., p. 267.

“3 F. Moy, 1855. “ Brit. Paleoz. Foss.,” p. 623, pl. 3 H, fig. 19, and
pl 3 1., fig. 728.

Streblodus oblongus—L. Agassiz, 1859. ‘ MSS., Enniskillen collection.”

55 KS Morris & Roberts, 1862. “ Quart. Journ. Geol. Soc.,”’ Vol. XVIIL, p. 101.

” ” R. Owen, 1867. “Geological Magazine,” Vol. IV., p. 62, pl. ii,
fig. 3.

7 “ Enniskillen,’ 1869. “ Catalogue Type Spec. Foss. Fish.,” p. 8

fp ie J. J. Bigsby, 1878. ‘Thesaurus Devonico-Carb.,” p. 365.

“ Posterior tooth elongate, narrow, sub-cylindrical, oblong, obliquely sub-truncate,
elliptically pointed at about an angle of 45° behind; anterior margin nearly at
right angles to the long axis of the tooth; anterior ridge very small, almost ob-
solete, scarcely defined from the equally wide flattened space between it and the
second oblique ridge, which is strongly defined on each side, but narrow and only
moderately convex ; posterior ridge very large, exceeding twice the width of the
middle ridge, separated from the middle one by a broad, moderately concave
sulcus, rather more prominent than the middle ridge, broadly and moderately
convex, abruptly rounded at its anterior edge, but gradually sloping towards the
posterior end; length of rathen small specimens about one inch two lines, of
middle ridge only two lines.” —(M‘Coy.)

Since the above description was penned a specimen has been found, consisting
not only of the posterior teeth, but also of two smaller teeth on each side of the jaw,
placed anteriorly to those described by M‘Coy (see Pl. LIIL., fig. 1) ; the teeth are
somewhat broken and badly preserved, and the parallel position in which they are
now placed is not the natural one, otherwise this unique specimen is extremely
valuable in affording information as to the position and character of the dental
apparatus of the fish. The jaw preserved appears to be the lower one, and consists
of a pair of the large posterior teeth, described by Prof. M‘Coy, one on each ramus
of the jaw—two inches in length and ‘8 inches in breadth. In front of these are
two teeth, much smaller and not very characteristically defined in this specimen.
The second tooth is about one-third the length of the large posterior one, and
equal in breadth to its length. It is sub-globose in outline, the posterior margin
flattened where attached to the contiguous tooth ; anterior margin also compressed
for attachment to the smaller anterior tooth. Crown surface obliquely convex,

 
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain, 425

whether consisting of a single ridge or more cannot be distinguished ; it is much
convoluted, its curvature being considerably more than a semi-circle. The two
anterior teeth, which occupied a position on each side the median suture of the
jaw, were about half the size of the second teeth, and appear to have been some-
what similar in form ; they are not sufficiently well preserved to afford any details
as to form or other characters.

The surface of the tooth is thickly covered with enamel, through which the denti-
gerous canals ascend from the bony substratum below, and cause the surface to present
a punctate appearance. The base or root of the tooth is thick, strong, and osseous, a
concavity, not so deep as the surface convexity, extends along the central axis of the
tooth. In this concavity Prof. M‘Coy records and figures a section of a specimen
(Brit. Paloz, Foss, pl 3H, fig. 19, and pl. 3 I, fig. 28), showing what is supposed to
be a young tooth, exactly concentric with the old one in outline, and presenting a
similar structure in section. He infers from this a vertical mode of succession of
the teeth. Several teeth of this genus, in the Enniskillen collection, exhibit
sections in various directions, but the appearance described by Prof. M‘Coy is not
presented in any instance even in the largest specimens. It is perhaps more
probable, considering the inrolled or convoluted character of the teeth and the
massive thickness of their bony base, that the teeth were constantly or periodically
enlarged by a growth along their posterior or inside margin. Evidence supporting
this view is afforded by the fact, that as the teeth increase in size the ridges and
intermediate depressions radiate with always increasing breadth from the con-
voluted anterior margin, and at the same time the tooth increases greatly in
thickness, and further, the anterior part of the tooth is most worn, whilst the
recently formed posterior surface not having been used to the same extent shows
very little sign of attrition.

An example is represented in Pl. LIII., fig. 4, which exhibits a portion of the
jaw preserved along with the teeth of the right side of the jaw and part of the
tooth of the left side. The portion preserved represents a wide expansion from
the teeth inwards, deeply-concayve, apparently having formed a firm base to this
part of the palate. Prof. Owen speaking of this specimen (“ Geol. Mag.,” Vol. IV.,
p. 62) says, “The symphysis of the jaw was shorter and the rami met there at a
more open angle in Streblodus than in Cochliodus; the anterior ends of the last
crushing teeth come into contact at the back part of the symphysis.” The
specimen is from Armagh, and forms part of the Enniskillen collection,

Formation and locality : Mountain Limestone, Armagh.

Ex. coll, Earl of Enniskillen.
Streblodus colei, Agass. (MSS.)

(Pl. LIIL,, figs. 5, 6.)

Streblodus colei—L. Agassiz, 1859. “MSS. Enniskillen Coll.,”
is ms Morris & Roberts, 1862. ‘Quart. Journ. Geol. Soc.,” Vol. XVIIL, p.101. |
= #8 Enniskillen, 1869. “Cat. Foss. Fishes,” p. 8.
: es J.J. Bigsby, 1878. “Thesaurus Devonico-Carb.,” p. 365,

3X2
''426 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

Only posterior tooth known; itis more elongate, narrower, flatter, and has a more
twisted conformation than the teeth of Streblodus oblongus. It averages 1°6 inches
in length and ‘55 inch in breadth across the posterior ridge, its widest part.
Crown, with three ridges and intermediate hollows. The first or anterior ridge
defines the anterior margin ; it is straight, acute, narrow, and at right angles to the
long axis of the tooth. The second or median ridge, extends at an angle of 45° to
the first one, it is ‘1 inch wide, semicircular, and rises from an almost uniformly
flat or slightly concave depression extending on each side the ridge with a total
diameter of half the length of the tooth. Posterior ridge, large, wide, expanding
obliquely from the anterior margin of the tooth backwards. Surface enamelled,
uniformly punctate; in several cases the surface is worn flat or hollowed by
attrition. Front of tooth inrolled downwards, the ridges extending therefrom
radially and increasing in size, especially the third one, backwards; posterior angle
acutely elliptical ; adpressed. Base conforms generally to the crown, thick, strong,
slightly concave. Towards the posterior ridge the tooth is *45 inch thick.

This species exhibits several well marked differences from S. vblongus. Its
general appearance is more attenuated, and in proportion to the length it is much
narrower. ‘The surface is less convex ; the posterior ridge is narrower, and extends
more obliquely across the tooth. The second ridge, which in S. oblongus is toler-
ably broad with a narrow sulcus on each side, in S. cole: is a narrow band rising
from a wide depression of the surface extending several diameters of the ridge on
each side.

Formation and locality : Mountain Limestone, Armagh.
Ex colt, Ear) of Enniskillen.

Streblodus egertoni, Agass. MSS.
(Pi itis *tigs: 7°82)

Streblodus egertoni—L. Agassiz, 1859. ‘MS. Enniskillen Coll.,”
“ _ Morris & Roberts, 1862. ‘Quart. Journ. Geol. Soc.,” Vol. XVIIL, v. 101
i, »  - Enniskillen, 1869. ‘Cat. Foss. Fishes, Types,” p. 8.
oy ie J. J. Bigsby, 1878. ‘“Thes. Dev.-Carb.,” p. 365.

Posterior teeth, small, oblong, sub-conical, deeply incurved in front; antero-
posterior section of anterior portion circular. Length ‘6 inch, breadth ‘3 inch.
Crown, anterior ridge, at right angles to longitudinal axis, forms a prominent
acutely angular anterior margin, surface slopes gradually in the opposite direction
forming a wide concave depression occupying half the breadth of the tooth ; there
is not a median ridge. Posterior ridge rises abruptly from the depressed concave
portion, extending obliquely from the convoluted anterior margin, gaining in breadth
posteriorly and ending in an obtusely rounded posterior margin. Surface
coarsely punctate.

This beautiful little species, dedicated to Sir Philip Egerton by his friend Prof.
Agassiz, whilst possessing the generic characters of Streblodus, is distinguished from
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 427

the species already described by its crown being divided into two principal parts,
a broad posterior ridge and anteriorly a wide sulcus or concave depression bounded
anteriorly by a well-defined ridge. The intermediate ridge, present in both the
species, S. oblongus and 'S. colet, in this species 1s absent.

Formation and locality ; Mountain Limestone, Bristol and Hook Point, County Wexford.
Ex coll. Ear) of Enniskillen.

Genus.—Deltodus, Agass. MSS.

Pecilodus—L. Agassiz, 1838. “Poiss. Foss.,” Vol. IIL, p. 174, indet.
re F. M‘Coy, 1855. “Brit. Paleoz. Foss.,” p. 640.
Deltodus —L. Agassiz, 1859. MS. Enniskillen Coll.
; pa ae 1866. “ Palsont, Illinois,” Vol, My 1.94,

Teeth, of varied form and size depending on their position in the upper or lower
jaw, possessing the following generic characters respectively :—

Upper jaw. “Teeth of medium or large size, thick and strong, triangular in
outline, more or less arched, sometimes enrolled in the line extending from the
longest and most acute angle to the opposite margin ; crown-surface sometimes
simply arched, more generally marked by 1-3 prominent ridges, running from the
basal margin towards the longest angle. In some species the triturating surface
is also undulated by a series of transverse obtuse ridges, parallel with the basal
margin, and mostly confined to the basal portion of the tooth. The crown surface
is uniformly punctate, the size and form of the pores varying in the different
species.” —(Newberry and Worthen.)

Lower jaw: probably three teeth on each side. Posterior tooth, large, more
or less quadrilateral in outline, thick and strong, prominent convexity occupies
greater portion of crown surface, depressed on the internal lateral area forming
an aliform expansion. Anterior margin curved sigmoidally, laterally straight,
converging backwards forming a subtruncate, recurved posterior extremity.

Second or median tooth: much smaller than the first, triangular in form,
convoluted posteriorly ; convex with a median ridge ; anterior margin circular,
laterally straight, converging backwards to an obtuse point.

Third or anterior tooth: small, triangular, expanded anteriorly ; rapidly con-
tracted backwards, prominent ridge extends across the tooth from front to back
with a wide expansion of the coronal surface towards the antero-lateral angle.

In some species the teeth are marked by transverse imbricating folds or
ridges, which may extend parallel with the anterior margin, over a part or the
whole surface of the tooth.

The palatal teeth included in this genus were originally placed by Prof.
Agassiz amongst the genus Peecilodus as two species P. sublevis and P. parallelus ;
they were, however, neither described nor figured. Prof. M‘Coy described and
figured the specimens as named by Prof. Agassiz in his work on the British
Paleozoic Fossils. He considered that the triangularly oblique aod aliform
''428 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

tooth was the terminal posterior one (here described as the tooth of the upper
jaw). The wider subquadrilateral palate is taken as the anterior tooth from
the same jaw. Poecilodus parallelus Ag. is described as a separate species, but
Prof. M‘Coy remarks that “from the character of its ridging, and from the
parts on the inner and outer sides of it, and the general agreement of the
margins, &¢., I have little doubt that this will ultimately prove to be the middle
tooth of the P. sublevis” (Deltodus sublevis). Since the above was written
specimens have been discovered with the teeth of P. sublevis and P. parallelus
cemented together in juxtaposition, and these prove the correctness of the
conviction of Prof. M‘Coy.
In 1858 whilst Prof. Agassiz was visiting this country he spent some time
In re-examination of the limestone palates in the Enniskillen Collection, tabu-
lating the result of his labours with a view to the publication of a memoir
on the subject at an early date. His death, unfortunately intervened before
the memoir was prepared. It was during this visit that the two genera Cochliodus
and Pecilodus were thoroughly revised and the great accumulation of specimens
led Prof. Agassiz to remove some of the species and form new genera for their
reception. Amongst the new genera were Psephodus, Streblodus, Deltoptychus,
Xystrodus, and Deltodus. Since ‘the institution of these genera, many new
species have been added to them from the Limestones of Illinois and other
American localities by Messrs. Newberry and Worthen and others.

Deltodus sublevis, Agass. MSS.
(Pl. LIL, figs 7-9.)

Peecilodus sublevis, L. Agassiz, 1838. ‘“ Rech. surles Poiss. Foss.,” Vol. IIL.,p. 174, indet.
5 parallelus, ne 1838. See hi ao kes 5 outtl. pAi4s i,
os sublevis, J. E, Portlock, 1843. “Geol. of Londonderry, &c.,” p. 461.
3 parallelus, S 1843. , 5 5 Sy te Ole
5 sublevis, C. G. Giebel, 1848. “Fauna der Vorwelt.,” Vol. L., pt. iii, p. 337.
x parallelus, i. 1848. sre ee, = Yoh; pt 01, 6,397.
sublevis, H. G. Bronn, 1848. ‘“ Nomencl. paleont.,” p. 1022.
sf parallelus, : 1848, +, 5; p. 1022.
5 sublevis, 1849. “ Enumerator palont.,” p. 647,
e paralellus, se 1849, 5 i p. 647.
- sublevis, J. Morris, 1854. “Cat. Brit. Foss.,” p. 340.
; parallelus, 5 1854, os er p. 340.
: sublevis, F. J. Pictec 1854. “Traité de Paléont.,” Vol. IL, p. 270.
e parallelus, o 1854, _ Vol. IE, p, 270,
ie sublevis, F. M‘Coy, 1855. “ Brit. Paleoz. Foss.,” p. 640, pl. 3 I, figs. 7, 8, 9.
ee parallelus, a 1855. »  p. 640, pl. 3 I, fig. 6.
Deltodus sublevis, L. Agassiz, 1859. MS. Enniskillen Coll.
x = Morris and Roberts, 1862. “Quart. Journ, Geol. Soc.,” Vol. XVIII, p. 100.
5 i Enniskillen, 1869. “Catal. Types Foss. Fishes,” p. 4.

ss a J.J. Bigsby, 1878, “Thesaurus Devonico Carb.,” p. 353.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 429

The teeth comprised in this species vary greatly in form. There is no
evidence that there was more than one tooth in each ramus of the upper jaw,
whilst in those of the lower one there were two, probably three, to each. The
teeth in the upper jaw were more or less triangular in outline, somewhat
flattened anteriorly, with a strong ridge extending from the posterior or apical
extremity towards the anterior margin. Greatest length 1-4 inches, width across
anterior surface ‘8 of an inch. A transverse section across the tooth exhibits
a sigmoidal curvature along its surface ; a strong ridge occupies half the surface
nearest to the median line; the remaining portion being depressed and concave.
The surface is uniformly punctate and a number of imbrications extend across
its surface parallel with the anterior margin. Anterior margin sigmoidally
eurved, bending with a convex line from the median antero-lateral. angle
towards the opposite one, which is considerably extended and acutely pointed ;
median lateral margin slightly convex; opposite or postero-lateral margin for
two-thirds its length straight, it then makes a flexure inwards, and with the
ridge of the crown forms an enrolled beak-like posterior termination, the
latter being thick and tumid. The base appears to conform generally with the
crown in outline; it is thin anteriorly and increases in thickness and strength
posteriorly. Its structure is open and porous with a coating of enamel on the
crown.

Taking the number of upper teeth hitherto found, about one half of them
answer to the above description, whilst the remaining half are reversed. They
appear to have been connected with each other along the median lateral margin
by a ligament or otherwise, one attached to each ramus of the Jaw. This is
rendered probable from the fact that such an arrangement would fit and correspond
with the form of the opposing teeth of the lower jaw ; the high convex ridge
of the upper tooth would be in contact with the hollow concave portion of the
teeth of the lower jaw, whilst the convex part of the lower teeth fitted to the
concave of those of the upper series. |

Lower jaw: teeth differ considerably from those of upper jaw. The two
central teeth were connected by their internal lateral margins over the median
line of the lower jaws, the opposite or external lateral margins being connected
with one, probably two posterior teeth on each ramus of the jaw. The pos-
terior teeth are quadrilateral, the sides nearly or quite straight, °6 inch in
length, -8 inch broad in front, and about half that width behind. Crown antero-
posteriorly round and convex, laterally depressed and concave from the external
margin to one-third the breadth of the crown. Remaining two-thirds con-
stitutes a broad deeply convex ridge extending the whole length of the tooth.
Surface enamelled, granulo-punctate, with a number of transverse equidistant
sulci, and intermediate ridges extending parallel with the anterior margin; in
some teeth they are almost obliterated by attrition presenting a simple smooth’
''430 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

surfaee. Anterior margin curved sigmoidally, conforming to the shape of the
crown, comparatively thin and acuminate, lateral margins straight; forming a
slight ridge projecting beyond the edge of the base.

Posteriorly the surface of the crown is convoluted, folding over with a helix-
like coil, the lateral margins of which converge until they form an obtusely
pointed angle. The base is thick and strong, especially where the ridge of the
crown is luighest, becoming thinner anteriorly ; in structure it is coarser and
openly striated. :

Connected with the posterior tooth a second one (see Pl. LIL, fig. 9), hitherto
regarded as a separate species under the name Pecilodus parallelus, has been
found, which leaves no room to doubt that it is in its natural position, and
from the character of its inside margin leads to the natural inference that a
third tooth occupied the front or median portion of the lower jaw. The second
tooth is triangular and ‘narrow, very much inrolled spiraliy, the curve exceed-
ing a semicircle.” Length ‘6 inch; anterior breadth-4 inch, converging back-
wards to a recurved point. A median ridge, occupying the major portion of the
surface of the crown, extends from the anterior margin backwards to the pointed
apex ; a second ridge is also present forming the lateral margin of the crown, and
between this and the median one there is a depression extending between,
and parallel with, the two ridges. The surface is more deeply sulcated than
that of the first tooth, but this is probably accounted for by the tooth being
subjected to a smaller amount of attrition.

Included in the collection are examples of teeth which approach near to an
equilateral triangle ; they are proportionately much broader across the anterior
margin and shorter laterally than the second pair described above ; posteriorly
they form an acute point slightly recurved, in other respects they are the
counterpart of the second tooth and it is probable that they were connected
with it, and formed the median tooth on each side the symphysis of the lower
jaw.

The more or less pointed posterior apex of the teeth composing this species, and
their ever widening anterior margin, together with the parallel sulci and ridges
which extend transversely across the surface have very much the appearance
that would be presented if they marked lines of additional growth and there
can be little doubt that these teeth have increased in size by successive additions
to their anterior margin. The general form and character of the teeth are ab-
normal and have no living representatives at the present time, so that it is
extremely difficult either to reconstruct the general form of the mouth or to
obtain a correct idea of the zoological position of the fish. Judging, however,
from the paucity of its remains, there can be little doubt that it was a cartil-
aginous one, and from its association with fishes of clasmobranch structure, and
animals of marine growth and habits, it may possibly be inferred with safety
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 431

that it was an inhabitant of salt water. The rounded form of the teeth, even
where most worn only rendered smooth, and never hollowed out as in some
other genera, may lead to the inference that the fish was wholly, or in part a
vegetable feeder.

Formation and locality : Mountain Limestone, Armagh.
Ex coll. Ear] of Enniskillen

Deltodus expansus, Davis.
(Pl IL ties: 3, 0. 14.)

Tecth, generally similar in arrangement to the type species, D. sublevis. Central
pairs of teeth, of upper and lower jaws, are the only ones identified. In each pair
they are widely expanded laterally, compared with D. sublevis. Teeth of the upper
jaw are 11 inch in length, and ‘8 inch across the anterior margin; posteriorly they
are constricted to an acute angle. Crown; asub-angular ridge extends from posterior
angle to the anterior margin, dividing the surface into two unequal parts; the
median portion slightly concave, with a marginal ridge extending along the edge
to which the opposite tooth was attached—on the opposite side the surface is
expanded, and forms a widely concave area with a lateral marginal ridge. The
whole coronal surface is punctate. Anterior margin circular, the outer antero-
lateral angle very slightly produced, lateral margins straight. or very slightly
convex, converging posteriorly to a somewhat acute and prominent apex,

Teeth of the lower jaw wider than long, a broad ridge extends antero-posteriorly
across the crown ; on the outer side of this ridge the surface is concave, depressed,
and widely expanded, terminating in a raised lateral margin, surface pustulate ;
transverse ridges absent.

This species differs from D. sublevis in its more angular form, and its widely
expanded concave surface. The posterior prominence is not so recurved and beak-
like, and the anterior margin is more rounded; it lacks the acutely pointed
antero-lateral angle, which is one of the characteristics of D. sublevis.

Formation and locality : Mountain Limestone, Armagh.
Ex. coll. Earl of Enniskillen.

Deltodus aliformis, M‘Coy.
(Pl, LYE feria)

Pecilodus aliformis—F. M‘Coy, 1848. “Ann. Nat. Hist.,” Sec. Ser., Vol. IT, p. 129.
is “i F. J. Pictet, ' 1854. “Traité de Paléont.,” Vol. IL., p. 270.
e s J. Morris, 1854. “Cat, Brit. Foss.,” p. 340.
i : F. M‘Coy, 1855. ‘Brit. Palscoz. Foss.,” p. 638, pl. 3 G., fig. 10.
e o Morris and Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. XVIII, p. 101.
e » . Young & Armstrong, 1871. “Trans. Geol. Soc., Glasgow,” Vol, IIL, Supt., p. 75.
a és J. J. Bigsby, 1878. ‘Thesaurus Devon. Carb.,” p. 363.

TRANS. ROY. DUB. SOC., N.S., VOL. I, Se
''432 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

Teeth, “ Wing-shaped or contorto-subtrigonal, narrow before, broad and sub-
truncate behind, inner straight margin thin, higher in the middle than at each end ;
the surface seeming concave from thence to the external oblique margin, which is
abruptly deflected, much thickened, rounded, strongly arched downwards at each
end, with a slight sigmoidal curve ; this ridge is crossed by seven or eight large
obtusely rounded wrinkles, which become obsolete as they approach the thin inner
margin—surface finely granuloso-punctate under the lens.” (M‘Coy).

A single specimen described by Prof. M‘Coy is in the Woodwardian Museum, at
Cambridge ; it is the same which is figured in the British Paleeozoic Fossils, Pl. 3 G.,
fig. 10. So far as I know there is no other specimen of the same species. It bears
a considerable generic resemblance to Deltodus (formerly Peecilodus) sublevis,
though differing considerably in details. It is apparently of the same genus, and
I have therefore transferred it from Peecilodus to Deltodus, retaining Prof.
M‘Coy’s specific name. Its strong sigmoidal contortion and the great size of the
transverse waves or wrinkles, distinguish it from Deltodus sublews, Ag.

Formation and locality: Black Upper Limestone of Derbyshire.
. Ex. coll. Woodwardian Museum, Cambridge.

Genus.—Deltoptychius, Agass., MSS.

Cochliodus— LL. Agassiz, 1838. <‘ Poiss. Foss.,” Vol. ILL, p. 174,"indet.
Cochliodus— =F, M‘Coy, 1855. © Brit. Paleoz. Moss.,” p, 621, pl. 3 L, fis. 24.
Deltoptychius—L. Agassiz, 1859. “ MSS. Enniskillen Coll.”

Palatal teeth of medium size, oblong or triangular in outline. Posterior
margin widest, diminishes in breadth forwards. Anterior, spirally convo-
luted. Crown, convex, raised with three more or less prominent ridges which
expand radially from the incurved anterior extremity ; posterior margin convex,
antero-lateral margin inrolled backwards, median margin thick, convoluted back-
wards. Surface minutely pustulate ; where worn it presents a punctate appear
ance. Base thick and strong, concave.

The teeth comprised in the genus Deltoptychius were originally considered by
Prof. Agassiz to be a species of Cochliodus, and were named by him Céechliodus
acutus (“ Poiss. Foss.,” Vol. III., p. 174), but were not described. Prof. M‘Coy,
accepting Agassiz’s definition, described and figured the specimens as C. acutus
(“ Brit. Paleeoz. Foss.,” p. 621, Pl. 3 I., figs. 24, 25, and 26). The two first figures
are those of the teeth of the lower jaw (those called posterior teeth); they exhibit
very imperfectly the convoluted, almost helicine infolding of the anterior portion
of the tooth.

The tooth of the upper jaw (anterior of M‘Coy), represents a very small and
imperfect specimen. In all the collection which forms the subject of the following
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 433

descriptions there is no distinct evidence of there having been more than a single

tooth to each ramus of the jaw. It is possible, nevertheless, that, as in the case of

Streblodus, there may have been smaller teeth situated in a position anterior to—
those of the lower jaw, and it may be well to withhold a firm opinion on the subject

until further negative or affirmative evidence shall have been adduced from future

discoveries.

The genus Deltoptychius differs from Cochliodus in the prominence and indivi-
duality of its ridges, especially the median and anterior ones, and the deeply
coneave sulcus separating them. The median ridge in the former extends much
more obliquely across the surface of the crown, causing the posterior margin to
assume a broader expansion than in Cochliodus.

Deltoptychius acutus, Agass., MSS.
(Pl. LL., figs 43-47.)

Cochliodus acutus— LL. Agassiz, 1838. Rech. Poiss. Foss.,” Vol. IIL, p. 174, indet.

a 3 J. E. Portlock, 1843. “Geol. Report of Londonderry, &e.,” p. 466.

5 . C. G. Giebel, 1848, ‘Fauna der Vorwelt,” Vol. IL, pt. 3, p. 336.

or We H. G. Bronn, 1848. ‘Nomencl. Paleont.,” p. 317.

6 s . 1849. <‘Enumerator Paleont.,” p. 647.

oo. . J. Morris, 1854. “Catal. Brit. Foss.,” p. 322.

. oe ye tecen, 1854, “Traité de Paléont.,” Vol. LE, p. 26%

. B. M'Coy, 1855. “Brit. Paleeoz. Foss.,” p. 621, Pl. 3 I., fig. 24.
Deltoptychius acutus—L, Agassiz, 1859. “MSS. Enniskillen Coll.”

5 5 Morris & Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. XVIIT,, p. 100.
Jochlioduscompactus—R. Owen, 1867.. “Geol. Mag.,” Vol. LV., p. 59, Pl. 1Y., fig, 1,
Deltoptychius acutus—Knniskillen, 1869. “Catal. Types Foss. Fishes,” p. 4.

Cochliodus acutus-- Young & Armstrong,1871. “ Trans. Geol. Soc., Glasgow,” Vol. III., spt., p- Ou.

Deltoptychius acutus—Armstrong, Young, isie MCh WW cone ae
and Robertson, ; oes : 3.9, Ds Oe:

J. J. Bigsby, 1878. ‘Thes. Dev. Carb.,” p. 353.

? 99

Prof. M‘Coy describes’the teeth as follows—* Posterior tooth, oblong, obliquely
attenuated behind at an angle of about 65°; anterior edge sloped backwards and
‘nwards at about 60°; surface with three very strongly marked, oblique ridges,
separated by deep concavities ; the first ridge most prominent, narrow, acutely
angulated, coinciding with the anterior edge, which is very deeply sloped, usually
separated from the adjoining concavity by an obscure narrow sulcus ; middle ridge
much broader and placed rather behind the middle of the tooth, sloping gradualiy
towards the base of the anterior ridge, but abruptly rounded into the deeper and
narrower concavity, which separates it from the posterior marginal ridge which is
prominent, narrow, and rounded, forming the posterior point of the tooth. Middle
tooth unknown. Anterior tooth, small triangular, marked with three narrow

prominent, very oblique ridges, the first coinciding with the posterior margin, and
Boe
''434 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

forming an angle of 50° with the outer edge, the anterior part of which forms the
third ridge ; the secondary ridge is more obtuse than the other two, and a little on
the posterior side of the middle, the intervening spaces deep, concave. Entire
surface, minutely granulo-punctate, by the extremities of the vascular canals
(averaging eight in one line), covered in some places with a very thin layer of
ganoine. Average length of posterior tooth one inch two lines, width at anterior
margin eight lines, length of anterior tooth seven lines, width of posterior margin
six lines.”

In the above description Prof. M‘Coy, describes each ramus of the jaw as con-
sisting of three teeth and describes two of them, the posterior and anterior ones;
the middle tooth being unknown. By a careful comparison of the teeth, which
form a very numerous suite, in the Enniskillen Collection, it has been found that
they may be naturally and easily divided into four groups, viz., the right and left
teeth of the upper jaw (M‘Coy’s anterior teeth) and the right and left teeth of the
lower jaw (called by M‘Coy, posterior teeth). The former described by Prof.
M‘Coy, as seven lines in length, average in the Enniskillen Collection 1:25 inch,
and several examples are more than 2 inches in length, and 1°5 inch across the
posterior margin; a larger size than is exhibited by the opposing teeth of the
lower jaw. The triturating surfaces of the teeth by the arrangement indicated
above correspond one to the other ; the hollow of the upper tooth corresponding
to the projections or ridges of the lower one, and vice versa ; this is especially the
case in some of the larger specimens, whose: surface is much worn, and considering
that it is quite impossible to ascertain the actual teeth which pertained to any
identical fish, the worn surfaces fit very accurately to those of the opposing jaw.

The teeth are strong and thick; in Jarge and well developed specimens the
thickness is equal to half the width. Anteriorly, the tooth is comparatively thin,
it increases in thickness towards the posterior and median portions and as is the
case with other Cochliodonts it is probably in this direction that the tooth has
increased in size, the growth being along the posterior edge.

Prof. Owen, in the Geological Magazine (Vol. LV., p. 62, pl. iv., fig. 1), describes
a tooth from the Limestone of Yorkshire, at present in the Woodwardian Museum,
Cambridge, as Cochliodus compactus ‘the predominance of the middle over the
posterior and anterior lobes giving the guiding surface of the tooth a more compact
and simple character.” It is an example of Deltoptychius acutus, Agass., and as
the latter name has priority, C. conypactus, Owen, can only be retained as a
synonym.

Formation and locality : Mountain Limestone, Armagh.
Hx coll, Earl of Enniskillen.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 435

Deltoptychius gibberulus, Agass. MSS.
(Pl. LIIL, figs. 18-19.)

Deltoptychius gibberulus—L. Agassiz, 1859. “ MSS. Enniskillen Coll.”
ss 5 Morris & Roberts, 1862. “ Quart. Journ. Geol. Soc.,” Vol. XVIII, p. 100,
s Enniskillen, 1869. “ Catal. Types. Foss. Fishes,” p. 4.
. 3 J. J. Bigsby, 1878. “Thes. Dev. Carb.” p. 353.

Teeth of lower jaw, more rhomboidal in outline than in D. acutus, and ridges less
acutely developed. Surface formed of three ridges with intermediate sulci, first
ridge corresponding with the antero-lateral or median margin, is obtuse and
rounded, descending at an acute angle to the edge of the tooth; middle ridge
broad and gibbous ovcupying a large proportion of the surface of the tooth, and
much wider than in D. acutus; separated from the anterior ridge by a narrow and
not very deep sulcus, which towards the anterior extremity is almost obliterated.
The third ridge is imperfectly preserved, but sufficient remains to show that it was
broader and more prominent than in D. acwtus; the sulcus intermediate between
this and the median ridge is shallow and wide, quite different trom the deep and
narrow concavity of D. acutus. Length, 1:25 inch, median margin ‘7 inch. Teeth
of upper jaw, sub-triangular in outline, greatest length 1:0 inch, along the antero-
lateral margin breadth, across posterior margin ‘7 inch, and of the median edge ‘7
inch. ‘The crown is formed of a large median ridge, and two much smaller and
less developed ones forming the antero-lateral and posterior margins of the tooth.
The median ridge is pointed and narrow anteriorly, gradually expanding posteriorly
into a broadly rounded convexity which occupies the greater part of the coronal
surface. The depression or suleus between the median and antero-lateral ridge is
somewhat deep anteriorly, widely expanded and shallow towards the posterior
margin; postero-lateral ridge slightly prominent, much lessso than in D. acutus ;
antero-lateral ridge, angular, small, much inferior to the median one in height, inter-
vening sulcus slight and narrow. This species differs trom Deltoptychius acutus in
the broadly expanded median ridges as compared with the less prominent ones of
D. acutus, whilst the lateral ridges, acutely prominent in the latter are compara-
tively small and obtuse in D. gibberulus. The posterior margin of the teeth of the
upper jaw of D. acutus is convex and rounded, extending considerably beyond the
antero and postero-lateral angles, whilst in D. gibberwlus the margin is almost straight.

Formation and locality : Mountain Limestone, Bristol. Hook-point, Ireland.
Lx, coll, Earl of Enniskillen.
''436 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

Genus.-—-Sandalodus, N. & W.
Sandalodus—Newberry & Worthen, 1866. “Geol. Sury. Illinois,” Vol. IL., p. 102.

“Teeth of medium or large size, thick and strong, sub-triangular or club-
shaped in outline, with one and sometimes two pointed extremities ; generally
somewhat twisted, slightly arched longitudinally, strongly so transversely ;
enamelled surface finely and uniformly punctate ; base deeply concave both ways,
curves following those of the surface of the crown ; towards the narrower end in
some species, one or two obtuse ridges running obliquely over the tooth as in
Cochliodus.”—N. & W.

The above is the description of the teeth of the lower jaw ; the following of those
of the upper one :—Large, thick, massive, triangular in outline, anterior extremity
pointed and convoluted inwards ; surface more or less concave, expanded posteriorly
and terminating with a broadly rounded posterior margin. External margin pro-
minent, angular, and inrolled. Enamelled surface punctate. Base generally
similar in form to the crown. A considerable number of specimens of this genus
have been collected at Oreton, in Salop, and from the Black Rock near Bristol.
The teeth from both localities are similar, and consist of the two forms
described above, and though they have not been found associated together in a
natural position, the fact that teeth of so large a size and identical texture are
found in two localities similarly associated and other minor considerations, renders it
almost certain that they are from the upper and lower jaws respectively of the same
species. The specimens figured, though they may not be from the jaws of the same
fish, fit each other with tolerable accuracy, the concave surface of the upper jaw
corresponding to the convex one of the lower.

The teeth of the upper jaw bear more than a passing resemblance to those of
Deltodus, and indicate a very close relationship between the two genera. The
teeth of the lower jaw are more like those of the posterior tooth of Streblodus
than Cochliodus, as stated by Messrs. Newbury and Worthen. The species now
under consideration are devoid of the slightest indication of “ obtuse ridges running
obliquely over the tooth,” they are quite plain and smooth.

The method by which the teeth of this genus have grown is very well shown in
the specimens figured. It does not appear probable that there was more than one
tooth to each ramus of the jaw. Those of the lower jaw are incurved, and to some
extent have enveloped the outer anterior margin of the jaw ; from this surface the
teeth expand inwards, and are largely developed backwards. The successive in-
creases in the size of the tooth are occasionally indicated, as on the tooth represented
by Figure 1, Plate LIV. This is exactly the method by which the teeth of the
genera Streblodus and Cochliodus increased in size, but whereas the dentition of
those genera is divided into two or three teeth with prominent transverse ridges ;

in the present one there is only one undivided tooth without ridges.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain, 437.

The teeth of the upper jaw have similarly developed from the outer margin of
the tooth : a transverse section of a tooth, (Plate LIV., Figures 3a, 4a), represents
the incurved lateral margin on the outside of the dextral tooth. The growth
in this instance very nearly approaches that of the tooth of Deltodus sublevis, and
serves to show the close connexion that exists between the genera Cochliodus,
Streblodus, and Deltodus. The suggestion is also forcibly impressed that the upper
teeth of the genera Cochliodus and Streblodus were probably somewhat similar
in form to Sandalodus and Deltodus, and though they have not yet been determined,
it is not improbable that they may be found amongst some of the teeth now con-
sidered either as separate genera or classified with some other one.

Sandalodus morrisu, Davis.
(Pl. LIV.,- figs. 1-6,)
Deltodus sp. ?—Morris and Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. XVII, p. 105. pl. 3,
fig. 1, Ta,

Teeth of lower jaw, large and massive, 4°5 inches ia length, and 1°75 in breadth
near the centre. Crown longitudinatly convex, transversely deeply convex, smooth,
polished, uniformly and finely punctate, surface evenly rounded, with the exception
of one or two flattened areas, apparently worn by attrition. Lateral margins
slightly rounded, extremity obtusely pointed. Base ‘4 inch thick near the end,
thinner in the centre of the tvoth, partakes generally of the form of the crown, but
is considerably constricted in extent.

Teeth of upper jaw, large in size, thick and strong, triangularly elongated,
posteriorly convoluted, length 4°0 inches, breadth anteriorly 1°8 inch. Crown in
longitudinal section, the surface is deeply convex, the external lateral margin
formed by a prominent ridge, which extends from the anterior apex towards the
posterior margin, becoming much expanded and proportionately depressed. The
internal lateral surface is more or less expanded and concave. ‘The surface of the
crown is uniformly and minutely punctate. Where the surface has not been
abrated each minute orifice is surrounded by a raised ring of black enamel, the
enamel being continuous from one pore to another, and covering the interme-
diate space. Posterior margin rounded or circular, considerably worn by attrition ;
the median lateral margin slightly convex, the opposite margin straight, angular,
and convoluted. A transverse fracture shows the tooth to be at least °4 of an
inch thick. The base is thick, strong, and fibrous in structure, full of ramifying
dentigerous canals in connexion with the punctate orifices of the surface enamel.
The base projects some distance beyond the crown along the posterior surface, and
also for a distance of an inch and a half along the inside lateral margin; in other
respects it conforms generally to the surface of the crown. The anterior portion
of the tooth is thinnest, and its thickness increases backwards in the same ratio
that the tooth increases in size. From the rough, porous, incomplete appearance
''438 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

of the posterior margin it may perhaps be inferred with reasonable probability,
that a process of growth increasing the size of the tooth along its broad posterior -
and inside margin may be indicated ; though there are no lines or ridges indicating
growth as in Deltodus sublevis, this method agrees with the other species in its
application. Thespecimens found at Bristol are smaller than those from OUreton, but
there does not appear to be any distinguishing feature which would lead to the
supposition that there is any specific difference between them.

Sandalodus morrisiti was found associated with several other species of fish-
remains in the Mountain Limestone at Oreton, in Shropshire ; amongst others.
were Orodus ramosus and species of Helodus, Cochliodus, Cladodus, Psammodus
and Ctenacanthus. It is figured without name or description in the “ Quar. Journ.
Geol. Soc.” Vol. XVIIL, pl. iti., figs. 2a, 2b, 2c, by Prof. J. Morris, and Mr. Geo.
E. Roberts.

The upper teeth of this species bear a superficial resemblance to an American
species, Deltodus grandis, Newberry and Worthen, from the Keokuk Limestone
of Illinois. It may, however, be easily distinguished by its generally rounded and
more circular form, and the absence of a deep sulcus extending longitudinally
parallel with the lateral ridge: in D. grandis the broader end of this sulcus is
strongly elevated.

I have taken the liberty of appending the name of Prof. Morris to this species,
he having first introduced it to notice in the paper cited above in 1862, Hitherto
it is the only described species of this genus from British strata.

Formation and locality : Mountain Limestone, Oreton, Salop; Black Rock, Bristol.
«x coll. Karl of Enniskillen ; Dr. Grenfell, and Bristol Museum.

Genus—Psephodus, Agass., MSS.

Cochliodus— L. Agassiz, 1838. -“ Rech. Poiss. Foss.,” Vol. IIT., p. 174, indet.
Helodus (partim)— _,, 1838. ries > 5 ih, ep ina,
Psephodus— 5s 1859. “MSS. Enniskillen Coll.”

Aspidodus— Newberry and Worthen, 1866. “Geol. Surv. Dlinois,” Vol. I., p. 92.

Palatal teeth varying greatly in size and form; outside sub-rhomboidal inclined
to pentagonal or oblong; surface, broadly convex with a decided obliquely
diagonal torsion. Diameter varies from 2°1 by 1°5 inches, to others which are
‘5 by ‘2 inch only. Anterior margin more or less convoluted, comparatively
broad ; surface expands posteriorly to nearly double the width of the anterior
margin. Posterior margin, rotund. Sides, straight where the teeth have been in
juxtaposition ; margins all vertically plicated. Coronal surface thickly coated
with enamel or dentine, porous or pustulate. Base, thickfand strong, conforms to
surface of crown but is considerably constricted in area.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 439

The teeth included in this genus were originally named by Prof. Agassiz, Coch-
liodus magnus and they have since been figured by Portlock (Geol. Rept. pl. 14a,
fig. 4) and described by Prof. M‘Coy (Brit. Paleeoz. Foss., p. 622). Admiral Jones, to
whom ichthyologists are indebted for much research and many valuable suggestions
in connection with the fish remains of the Mountain Limestone, indicates a proba-
bility that the teeth of Cochliodus magnus and Helodus planus belonged to the same
fish. He does not, however, suggest any possible arrangement of the palates. —
The inference is very likely correct, and if a tolerably perfect example of the palate
should fortunately be discovered, it will probably be found to consist of three
teeth of the species hitherto known as Cochliodus magnus on each ramus of the jaws,
increasing in size backwards, and a number of teeth of Helodus planus arranged
between the jaws, forming a close pavement-like series also increasing in size
backwards.

During the year 1858, Prof. Agassiz removed this group of teeth from the
genus Cochliodus and instituted the new genus Psephodus for its accommodation. The
so-named types remained in the collection of Lord Enniskillen but like many others
were not described.

In the Paleontology of Illinois (Vol. IL, p. 92) Messrs. Newberry and Worthen
describe and give figures of a number of palates from which they have originated
the genus Aspidodus. At the same time they indicate its relationship to the teeth
of Cochliodus maynus, Ag., and [Telodus planus, Ag., and suggest the latter should
be included in their new genus. There is little doubt that they are generically
identical and should be joined together in one genus, but as priority is generally
taken as the guide in instances of synonymic nomenclature, it will be evident that
Agassiz’s genus Psephodus must be retained and the genus Aspidodus, Newberry
and Worthen, merged with it.

Psephodus, magnus, Agass., MSS.
(PL EV gee

Cochliodus magnus—L. Agassiz, 1838. “Rech.sur Ll. Poiss. Foss.” Vol. III., pp. 174, 384 (indet).
Helodus planus, 1838. a o “ oe bias vee
Cochliodus;magnus—J, E. Portlock, 1843. “Rept. Geol, Londonderry, &c.,” p. 466, pl. XT Va, fig. 4.
Helodus planus, 3 1843. o 5 » 462.

Cochliodus magnus—C. G. Gebe, 1848. “Fauna ae Vorwelt,” Vol. I., pt. 3, p. 336.
Helodus planus, iy 1848. % y :, 5 Ly pe 8, pe Sad,
Cochliodus magnus—-H. G. Bronn, 1848. ““Nomencl. Paleont.,” p. 317.

Helodus planus, . 1848, s ~ p-. 583.

Cochliodus magnus, ie 1849. “numerator Paleont.,” p. 647.

Helodus planus, Be 1849. ee Ay p. 647.

Cochliodus magnus—J. Morris, 1854. “Catal. Brit. Foss.,” p. 322.

Helodus planus, B 1854. x ao se pede.

TRANS, ROY, DUB. SOC., N.S., VOL. I. Bo
''440 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britaw.

Cochliodus magnus—F. J. Pictet, 1854. ‘‘Traité de Paleont.,” Vol. IT., p. 267.
Helodus planus, 1854. ee - on LE 5p. 267,
Cochliodus magnus—F. M‘Coy, 1855. “Brit. Paleeoz. Foss.,” p. 622.
Helodus planus, : 1855. . ne <P. 051. pl 31, figs. 12-15.
Psephodus magnus—L. Agassiz, 1859. ‘MSS. Enniskillen, Coll.,”
Cochliodus magnus—Morris & Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. XVIIL, p. 100.
Psephodus magnus, # 1862. 4 _ ; 5 3 OM VELL, p POF.

- Enniskillen, 1869. Catal. Types, Foss. Fishes,” p. 7.
Cochliodus magnus—Young& Armstrong, 1871. “Trans. Geol. Soc. Glasgow,” Vol. III., supt. p. 70.
Helodus planus, 5 . Sil 55 2 5 3 »,° LiL, suph po,
Cochliodus magnus | espe, young, \ 1876. ‘Catal. West. Scot. Foss.,” p. 61.

and Robertson,
Helodus planus, . 1876. os - np sp: 62:
Psephodus magnus, 3 1876. e a a erp: Oo:
a a J. J. Bigsby, 1878. “Thesaurus Devonico-Carb., p. 364.

a :; L, G. de Koninck, 1878. ‘Fauna du Cale. Carb. d. 1. Belgique,” p. 60, pl. iv.,
figs. 14-17.

Posterior tooth irregularly pentagonal, or sub-rhomboidal, broadly convex,
moderately arched from side to side, and more or less inrolled at the outer or
anterior margin ; the antero- and postero-lateral margins diverge from the anterior
portion of the tooth; the antero-lateral margin straight or slightly concave, forms
a sutural edge for the attachment of the median tooth; posterior margin rounded.
““MiddJe tooth obscurely trapezoidal, having a broad, moderately convex inner
margin, from whence the surface is uniformly and gently arched towards the
opposite very short side, or obtuse slightly inrolled outer margin; anterior and
posterior sutural edges diverging obliquely from the short outer margin ; posterior
one longest. Anterior tooth subtrigonal, obliquely semi-elliptically pointed in front,
and with an oblique nearly straight sutural edge, marking the posterior face of the
triangle.” The edges of the teeth are all more or less vertically crenulated and the
surface uniformly punctate.

The Helodus-like teeth occupying the intermediary portion of the palate are
“irregularly elongate, oblong with a slight oblique diagonal twist, narrowed, and
rotundato-subtruncate at the ends, between which the crown widens; widest nearer
to one end than the other ; surface flattened obtusely, slightly convex”. They are
crenulated or plicated along the edges, and the surface is punctate as in the teeth
situated on the jaws.

The large number of teeth comprised in this species are only roughly included
in the above descriptions. Their forms are very complex and scarcely two are
alike. It appears possible, however, to distinguish amongst the larger specimens
two distinct sets, which in all probability belonged respectively to the upper and
lower jaws. In the one the crown is semi-globose in section from front to back
and highly convex laterally ; occasionally one or other part of the crown is worn
or abraded by attrition to a flat surface (Pl. LV., fig. 10). In the other the teeth are
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 441

much flatter and more nearly pentagonal in outline. Their surface is worn into deep
hollows seemingly by impact with the rounded teeth of the opposing jaw. In a
few cases the thick dentine is completely worn through, exposing the bony structure
below. The base in the larger specimens is quite half an inch in thickness. The
smaller teeth, of which there are numerous examples, appear to have been attached.
to the antero-lateral extremity of the larger ones, they are broadest at the posterior
sutural margin and gradually diminish in size anteriorly, where they are connected
with a third anterior tooth which is trigonal in form, ending in front with an
obtusely pointed angular margin (Pl. LV., figs. 1, 2, 3). It is not probable that more
than three teeth existed on each side of the jaw and the teeth hitherto known as
Helodus plunus, Ag., occupied the intervening portion of the palate. An example
(Pl. LY., fig. 6) shows a Helodoid tooth to have occupied a position in front of the
anterior tooth as well asthe palatal space behind.

Formation and locality : Mountain Limestone, Armagh: Kendal.
Ex coll. Karl of Enniskillen.

Genus.—Pecilodus, Agass., MSS.

Palatal teeth, length equal to half the breath; subtrapezoidal in outline.
Crown, surface raised into folds extending radially from the posterior basal
extremity ; transverse lines of ridges extend parallel to the posterior margin
decreasing in size forwards. Posterior margin sigmoidally sinuous ; postero-lateral
margin more or less straight ; antero-lateral margin convex or straight, converging
forwards. Anterior margin, narrow, convoluted downwards.

Median tooth narrow, triangular in outline.

The genus Peecilodus was instituted by Professor Agassiz (Poiss. Foss., Vol. ILIL.,
p. 174) and included six species, viz., P. jonesii and P. transversus, P. angustus and
P. obliquus, P. sublevis and P. parallelus, of these more recent discoveries have proved
the two latter species to be teeth from the jaw of the same fish and that they differ
in character and form from the typical P. jonesii so completely, that in 1858
Professor Agassiz removed them from the genus Peecilodus and made them the type
of a new genus which he named Deltodus: P. parallelus, being the median tooth of
P. sublevis. The two species P. jonesii and P. transversus, were also proved to
belong to the same fish and the latter has been merged into the former.

Professor M‘Coy (Brit. Palzeoz. Foss., p.638), described the genus Pecilodus and
in addition to the Agassizian species P. jonesii (with P. transversus), P. obliquus,
P. parallelus and P. sublevis described two new species, P. aliformis and P. fovevlatus.
The last, from the Carboniferous Limestone of Derbyshire, appears to possess the
characters of the genus whilst P. aliformis is without doubt a Deltodus and must be
relegated to that genus. The description of the genus as given by Professor M‘Coy
is in consequence of the separation of the teeth to form the genus Deltodus,

inappropriate and insufficient ; the one above is therefore substituted. ,,,
''442 On the Fossit Fishes of the Carboniferous Limestone Series of Great Britain.

Peecilodus jonesii, Agass., MSS.
(Pl. LIIL., figs. 20-23.) -

Pecilodus jonesii— L. Agassiz, _ 1838. “ Rech. Poiss. Foss.,” Vol. III., p. 174 (indet).
_ transversus, - 1838. . 5 - Vol. IIT., p. 174 (indet).
- jonesii— J. E. Portlock, 1843. “ Rept. Geol., Londonderry, &c.,” p. 468, pl. 14a, fig. 6.
, transversus, ; 1843. ‘ - i p- 468, pl. 14a, fig. 7.
ss jonesii— C. G. Giebel, 1848. “Fauna der Vorwelt,” Vol. I., pt. 3, p. 337.
i transversus, 5 1848. se . 3 Noll pt. 35. ps sole
a jonesii— H. G. Bronn, 1848. “ Nomencl. Paleont.,” p. 1022.
es transversus, 5 1848, sa ps, L022.
33 jonesii, BS 1849. ‘‘Enumerator Paleont.,” p. 647.
; transversus, . 1849. e 5 p. 647.
5 jonesii— J. Morris, 1854. “ Catal. Brit. Foss.,” p. 340.
3 transversus, 3 1854. e 3 3»  p- 040.
. jonesii— F. J. Pictet, 1854. “ Traité de Paléont.,” Vol. II., p. 270.
transversus, 7 1854. ys > Vol Th. p. 270:
s jonesii— F. M‘Coy, 1855. ‘“ Brit. Paleoz. Foss.,” p. 639.
‘5 jonesii— L. Agassiz, 1859. “MSS. Enniskillen Coll.”
3 = - Morris & Roberts, 1862. ‘Quart. Journ. Geol. Soc.,” Vol. XVIII. p. 101.
5) s Enniskillen, . 1869. “Catal. Types Foss. Fishes,” p. 7.

Armstrong, Young 1876
and Robertson, es

6 is J. J. Bigsby, 1878. ‘Thesaurus Devon.-Carb.,” p. 363.

“ Catal. West. Scot. Foss.,” p. 62.

Two, probably three teeth were attached to each ramus of the jaw. Posterior
tooth thick and strong, obliquely elliptico-trapezoidal in outline; average breadth
‘7 inch, length ‘35 inch. Coronal surface tumid, convex somewhat flattened
towards the antero-lateral margin, moderately convoluted anteriorly ; one deep
oblique concavity, about one-third the breadth from the anterior margin, divides
the surface into two large oblique unequal lobes, extending radially from the con-
voluted anterior margin ; the first lobe slopes gradually so as to form a prominent
anterior articular margin; the second or posterior lobe, obtusely rounded, extends
parallel with the postero-lateral margin ; a number of transverse, strongly marked,
projecting ridges extend across the surface, roughly parallel with the posterior
margin, decreasing in size forwards, they are separated by deep hollows. The
surface is coated with enamel, finely and evenly punctate where unworn, where
the surface has been worn, sections of the punctures are exposed. Posterior margin
oroad, sinuous with a bold convexity conforming to the posterior lobe of the crown ;
antero-lateral margin straight ; postero-lateral margin convex, forming with the
anterior one a more or less acute angle, and converging backwards to the com-
paratively narrow anterior margin which is convoluted inwards. Basal portion
conforms generally to the surface.

The anterior or median tooth, named by Prof. Agassiz Pwcilodus transversus,
was attached to the one described along its antero-lateral margin. Its form is
triangular, length, 45 inch; breadth, ‘3 inch across the posterior extremity,
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain, 443

diminishing gradually forwards and ending in an obtuse point. The crown is
convex, anteriorly convoluted, a central ridge extends from front to back of the
tooth from which the surface slopes on each side, terminating in a slightly raised
lateral margin. There are about eight trarsverse, wide, large, and rounded folds
or wrinkles. The whole surface is enamelled and punctured. Posterior margin
convex, depressed. Lateral margins straight or slightly convex, anterior ones
incurved, pointed.

An example in the Enniskillen collection shows the tooth, P. transversus, Ag.,
in juxtaposition with the anterior lateral margin of the tooth of P. jones, Ag.
It occupies an exactly corresponding position to the second tooth of Deltodus, and
in some respects bears a resemblance to that tooth.

A comparison of the above description and the figures (Pl. LIIL., figs. 20-23),
with those given by Portlock in the Geological Report referred to, show that the
two specimens figured by Portlock are both included in the species P. jonesii as
originally named by Agassiz, and that Agassiz’s species P. transversus was not known
to Portlock, his definition of the difference between the two being, that in the
latter “the folds are continued more across the tooth, are less twisted, and not so
strong.” The description given by Prof. M‘Coy of Pwecilodus jonesit (+ P. trans-
versus) is evidently founded on that of Portlock ; the specimens are not figured,
but a reference to those in the Geological Report is given; there is no allusion to
the median teeth, smaller, narrow, and more triangular in form, which Prof.
Agassiz named P. transversus, and M‘Coy appears also to have accepted the
slightly raised forms of the original P. jonesw as the P. transversus, Ag. An
examination of the type specimens named by Prof, Agassiz in the Enniskillen
collection proves both authors to have been im error.

Formation and locality : Carboniferous Limestone, Armagh.
Ex coll. Earl of Enniskillen.

Peecilodus obliquus, Agass., MSS.
(Plo LTE, fier 247)

Pecilodus obliquus—L. Agassiz, 1838. “Rech. sur les Poiss. Foss.,” Vol. IIT., p.174, indet.
7 mas J. E. Portlock, 1843. “Rept. on Geol. Londonderry,” p. 461.
zs 3 C. G. Giebel, 1848. “Fauna der Vorwelt,” Vol. L, pt. 3, p. 337.
- i FH; G. Broun, 1848. “Nomencl. Paleont.,” p. 1022.
4 ‘ H.G. Bronn, 1849. “ Enumerator Paleont.,” p. 647.
Z J. Morris, 1854. “Cat. Brit. Foss.,” p. 340.
s 55 J. . Pictet, 1854. “Traité de Paléont., Vol. IL, p. 270.
. . F. M‘Coy, 1855. “Brit. Paleoz. Foss.,” p. 640, pl. 3 L, fig. 5.

Morris and Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. X VIIL, p. 101.
Young and Armstrong, 1871. ‘Trans. Geol. Soc. Glasgow,” Vol. ITL., supt. p. 75.

Armstrong, Young,and ;
29 2) 5) oO? coe Nis ” 192
Robertson, \ 1876. “Cat. West Scot. Fossils,” p. 62.

a 7 J. J. Bigsby, 1878. “Thesaurus. Devonico-Carb.,” p. 363.
''444 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

Teeth, “Terminal posterior tooth sub-cylindrical, obliquely attenuated semi-
elliptically at the posterior end, abruptly truncated at an angle of 80° in front,
strongly convoluted, with three very strongly-marked, very prominent, nearly
equidistant ridges ; the lateral ones formed by the thickened reflexed margins of
the anterior and posterior edges; the middle one thicker than the others, and
slightly more prominent, bounded on each side by a very broad, deep concavity ;
the concavities are crossed by strong, subequal, slightly irregular longitudinal
wrinkles, separated by deep sulci, which only indent the oblique transverse ridges
of the convoluted outer portion ; the whole surface strongly granulo-punctate.”—
(I Coy.)

he length of the specimen figured is 75 of an inch across the lateral diameter
and ‘4 of an inch antero-posteriorly. It differs from P. jonesii, Ag. in several
particulars ; the postero-lateral angle is less prominent, whilst the radiating ridges
on the surface are much more so, especially the two lateral ones. The posterior
half of the tooth in P. jonesii is large compared with the remainder, whilst in
P. obliquus it is smaller and hollowed by the deep concavity between the postero-
lateral and median ridges. The inside margin is much more inrolled in P. obliquus.
than in P. jones, Ag. It has been hinted that some relationship may be found
to exist between the Sirenoid Ganoids and the Cochliodonts; should such be the
case, it will probably be found that the teeth of this species will approach as near
as any to connect the two forms together.

Formation and locality: Mountain Limestone, Armagh.
Lz coll. Karl of Enniskillen.

Peecilodus corrugatus, Davis.
(PITA; fig. 25).

Teeth, probably anterior, sub-triangular, *45 of an inch long, and ‘3 of an inch
in breadth. Lateral margin slightly curved, gradually approaching and meeting
posteriorly, forming a slightly inrolled point. Anterior margin circular, depressed.
The surface of the crown is slightly convoluted antero-posteriorly, and in the
opposite direction convex. Parallel with the anterior margin four wide, obtusely-
prominent ridges occupy the central portion with deep intermediate sulci—the
ridges terminate before reaching the lateral margins. Attached to the tooth is a
portion of a second, probably the larger posterior tooth. The surface is uniformly
punctate.

This exumple, from the Upper Limestone beds of Wensleydale, is similar in form
to the anterior tooth P. jones, Ag. It differs in being rather flatter, and in the
surface arrangement. ‘lhe crown of P. jonesii is raised medially in the form of a
ridge sloping to each side, with about eight transverse folds. In the present in-
stance four prominent transverse ridges occupy the surface with a special median one.

Formation and locality: Upper Limestone, Wensleydale.
Ex. coll. W. Horne, Esq., Leyburn.
''On the Fossil Fishes of the Carboniferous Iimestone Series of Great Britain. 445

Peecilodus foveolatus, M‘Coy.
(PL Ei ae 26.)

Peecilodus foveolatus—F. M‘Coy, 1848 “Ann. Nat. His.,” Sec, Ser., Vol. If, p. 122.
: “ F. J. Pictet, 1854.  Traité de Paleont.,” Vol. IL, p. 270.
- is J. Morris, 1854. “Cat. Brit. Foss.,” p. 340.
95 F. Moy, 1855. Brit. Paleoz. Foss.,” p.'639., pl. 3 G.; fig; 11
as me Morris and Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. XVIII, p. 101.
J. J. Bigsby, 1878. ‘Thesaurus Dev. Carb.,” p. 363.

Teeth, “Longitudinally clavate, depressed, nearly three times longer than
wide ; terminal end narrow, subtruncate ; surface obliquely crossed by nine or ten
thick, flat, imbricating ridges, varying from one line to half a line wide ; they run
nearly straight, but each has got an abrupt, angular bend about the middle which
makes the posterior half of each edge seem about half a line further out than the
anterior half—each imbrication has one, or rarely two rows of large, equidistant
puncta, or small pits.”

This species is founded on a fragment of a tooth, which still remains unique ; it
is in the Woodwardian Museum, Cambridge. It is about 1:2 inch in length. Its
narrow, elongate form and more numerous, flat, imbricating ridges, the row of
notch-like curves, one on the edge of each, and the regular rows of puncta, dis-
tinguish this species from P. jonesti, Ag.

Formation and locality: Mountain Limestone, Derbyshire.

Ex. coll. Woodwardian Museum, Cambridge.

Peecilodus gibbosus, Davis.
(Pl. TL fies.27, 2fa7)

Posterior teeth, probably of lower jaw, sub-pentagonal in outline, breadth
‘6 inch, length slightly less. Crown antero-posteriorly deeply convex, and
inrolled posteriorly ; surface almost equally divided into two parts. Extending from
the antero-lateral margin, which is slightly raised, one half the surface is formed
by a wide and deep depression, transversely straight and smooth, longitudinally
convex, and in front its area much constricted. ‘The latero-posterior half is occupied
by a bold gibbous ridge, posteriorly broad, converging and profoundly convoluted
posteriorly ; its surface is traversed by a considerable number of segment-like
transverse sulci which, however, do not extend to the depression of the surface on
either side ; the latcro-posterior margin is slightly raised in the form of a ridge,
between it and the median one there is a narrow groove-like depression. Coronal
surface enamelled, and punctate. The puncta on the median ridge are larger and
more deeply impressed than on the remaining portions of the surface. Posterior
margin sinuous, deeply concave where the depressed surface of the crown impinges.
''446 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

Laterally the margins are nearly straight—the median one converging obliquely
towards the posterior margin, which is comparatively narrow and convoluted
inwards. Base not well defined.

This species is defined by well-marked differences from Pecilodus jonesw described
above, and P. obliqguus, M‘Coy (Brit. Paleeoz. Foss., p. 640, pl. 3 L., fig. 5). The
latter is characterized by three strongly convoluted, very prominent, nearly equi-
distant ridges, with intermediate concavities, the latter crossed by irregular
transverse wrinkles, which do not generally extend over the surface of the ridges.
P. jonesii has two sub-parallel ridges, with one deep intermediate depression, and
the whole surface is divided by transverse wrinkles or folds. The species described
above has only one important median ridge, larger and broader, in proportion to the
size of the tooth, than those of either P. jones or P. obliquus, and the transverse
folds extend only over the ridge, and do not traverse the depressed.-portions of the
surface. In P. gibbvsuz the depressed postero-lateral portion is much constricted
in area between the anterior and posterior margins—a character which does not
obtain in the others.

Formation and locality : Mountain Limestone, Armagh.
Ex, coll. Earl of Enniskillen.

Genus.—Tomodus, Agass. (MSS.)

Palatal teeth, large, thick, massive, triangular or sub-rhomboidal in outline, con-
volute. Crown, surface antero-posteriorly semi-rotund, laterally convex, thickly
coated with enamel or dentine, punctate. Anteriorly more or less pointed,
laterally diverging and forming a broad posterior margin. Base, thick, osseous.

This genus differs from all the other Cochliodont teeth in its thick massive and
triangular characters. The postero-lateral margin has evidently been connected
with a second tooth or has formed the median line over the jaw, in which case
there would probably be only two teeth to each jaw, one on each ramus. The
latero-posterior margin is thinner and does not present the appearance of having
been attached to another tooth.

Tomodus convexus, Agass. (MSS.)
(Pl. LV., figs. 15-18.)

Tomodus convexus — L. Agassiz, 1859. “MSS. Enniskillen Coll.”

; . Morris & Roberts, 1862. “ Quart. Journ, Geol. Soc.” Vol. XVIIL., p. 101.
Cochlicdus 5) R. Owen, 1867. “ Geol. Mag.” Vol. IV., p. 62, pl. 4, figs, 2-5.
Tomodus 5 Enuiskillen, 1869. “ Catal. Types Foss. Fishes,” p. 8.

Armstrong, Young ; 5
: Ley oe 1876. “Catal. W. Scot. Foss.” p. 63.

J. J. Bigsby, 1878. “Thesaurus Devonico-Carb,” p. 365.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 447

Palatal teeth of two sizes with- distinctive characters. Larger teeth triangular,

length antero-lateral margin 1:25 inch; postero-lateral margin 1°5 inch, and
posterior margin 1*1 inch, Crown, antero-posteriorly deeply convex or semi-
globose ; laterally convex, even and smooth except where a sulcus extends across
the postero-lateral angle of the tooth ; thickly enamelled and minutely and closely
punctate. Anteriorly the tooth is pointed and convoluted, the lateral margins
diverge posteriorly ; posterior margin straight or slightly convex ; postero-lateral
angle produced with a somewhat sinuous flexure. . Base ‘3 inch thick in centre,
thins out slightly towards both the anterior and posterior margins. Smaller teeth,
oblong or sub-rhomboidal in outline. The surface is laterally concave, the margins
being raised and forming a ridge along each side.
- The specimen from the Carboniferous limestone of Bristol referred to by Prof.
Owen (Geol. Mag. Vol. IV., p. 62), as Tomodus convexus, Ag., which forms part of
the collection at the Woodwardian Museum, Cambridge, presents every appearance
of being, so far as the teeth are concerned, a defective and much broken specimen
of Cochliodus contortus, Ag. ; as remarked by Prof. Owen it is the most completely
preserved specimen of a mandible of a Cochliodont known. It will be treated with
greater detail when speaking of Cochliodus in this memoir.

Formation and locality : Mountain Limestone, Bristol.
Fx coll. Ear] of Enniskillen.

Genus.—Xystrodus, Agass., MSS.

Syn. Cochliodus (pars.)—Agassiz, 1838. ‘Rech. Poiss. Foss.,” Vol. TIL, p. 174.
>» eeellodus .. ‘ 1838. is a Vol. IIL, p. 174.

Palatal teeth more or less triangular in outline, medium or small size, slightly
convoluted and acutely pointed anteriorly: antero-lateral margin forms a
convex articulating ridge raised higher than the general surface of the crown,
the remainder of which is depressed and concave, expanding in breadth posteriorly.
Posterior margin sigmoidally convex. forming an acute angle with the postero-
lateral margin. Surface enamelled, punctate or pustulate—the puncta sometimes
arranged so as to fall into regular lines. Base thick and strong.

TRANS, ROY. DUB. SOC., N.S., VOL, 1. 4A
''448 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britaan.

Xystrodus striatus, Agass.,, MSS.
(PL IVS igs: 7,6) 10)

Cochliodus striatus—L. Agassiz, 1838. ‘¢ Rech. sur les Poiss, Foss.,” Vol. ILI., p. 174.
a e J. E. Portlock, 1843. “Rept. Geol. Londonderry, &c.,” p. 461.
mS a ©. G,. Giebel; 1848. ‘“ Fauna der Vorwelt,” Vol I., pt. 3, p. 336.
of v H. G. Bronn, 1848. “ Nomencl. Paleont.,” p. 317.
55 ih 4 1849. “ Enumerator Paleont.,” p. 647.
i joe eee J. Morris, 1854. ‘Catal. Brit. Foss.,” p. 322.
: 5 F. J. Pictet, 1854. “Traité de Paléont., Vol. IJ., p. 267.
5 F. M‘Coy, 1855. ‘ Brit. Palseoz. Foss.,” p. 624, pl. 3 I, fig. 27.
Xystrodus striatus—L. Agassiz, 1859. “MSS. Enniskillen Collection.
5 3 Morris and Roberts, 1862. ‘Quart. Journ. Geol. Soc.,” Vol. XVIII, p. 101.
; e Enniskillen, 1869. “Cat. Types Foss. Fishes,” p. 9.

A str AY ) ¥ ”
2 | eee j 1876. “Cat. W. Scot. Foss.,” 63.

?

. a J. J. Bigsby, 1878. ‘Thesaurus Dev.-Carb.,” p. 367.

«Terminal tooth aliform, triangular, very much broader than long ; long articular
margin forming an angle of about 35° with the outer edge; along this articular
margin is the most prominent part of the surface, forming an obtusely rounded,
slightly sigmoid ridge ; the remainder of the surface being flattened and extending
with a slight concavity to the terminal point, which is nearly rectangular and
obtuse. Surface with a fine sharp, granulo-punctation having the usual quin-
cuncial arrangement on the long obtuse convexity of the articular ridge, and on
the opposite, flattened, terminal angle; but on all the intermediate portion the
punctee tall into regular, slightly flexuous lines, extending longitudinally nearly at
right angles to the articular side ; about twelve of the lines of punctures in the
space of one line,” —(M/‘Coy.)

The number of teeth comprised in the above description by Prof. M‘Coy has
been greatly amplified since he penned the description, and asa result, a comparison
of the teeth in Lord Enniskillen’s collection proves either that there are two or three
species, or that some of the teeth are from the upper, and others of different form
from the lower jaws. Prof. Agassiz regarded them as different species, and, there
being not the least evidence to the contrary, they will be regarded as separate
species at present. The Xystrodus striatus (Cochliodus striatus, M‘Coy)
consists of teeth, as stated in the description above, whose surface punctation falls
into lines roughly parallel with the posterior margin of the tooth. The teeth
are somewhat different in form to those described by M‘Coy, an average specimen
being °6 inch along the raised articular margin, and an equal length across
the posterior face, whilst the longest side is ‘9 inch in length. The anterior
margin is considerably inrolled and in this bears some resemblance to the upper
tooth of Deltodus sublevis, as well as in its apparent method of growth. The
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 449

articular margin is very considerably raised above the remaining portion of the
crown. The base is thick and conforms generally to the form of the superior
surface. About one-half the number of teeth are the reverse of the others and as
in Cochliodonts generally, they appear to have been implanted on the opposite rami
of the jaws to form palates suited to crush the shells of molluscs or other hard

covering of the animals on which they fed.

Formation and locality : Mountain Limestone, Armagh.
Ex coll. Earl of Enniskillen.

Xystrodus angustus, Agass., MSS.
(PL LV; figs; 19).20,21.)

Pecilodus angustus—L. Agassiz, 1838. ‘Rech. Poiss, Foss.,” Vol. IIL, p. 174, indet,
Ne 4 C. G. Giebel, 1848, <‘‘Fauna der Vorwelt,” Vol. L., pt. 3. p. 337,
He a H. G. Bronn, 1848. ‘Nomencl. Paleont.,” p. 1022.
5 es H. G. Bronn, 1849. “Enumerator, Palexont.,” p. 647.
5 iS J. Morris, 1854, ‘Cat. Brit. Foss.,” p. 340.
. - F, J. Pictet, 1854, “Traité de Paléont.,” Vol. IL., p. 270.
Xystrodus angustus—L. Agassiz, 1859, “MSS. Enniskillen, Coll.,”
ee i Morris & Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. XVIIL, p. 101,
% Bs Enniskillen, _ 1869. “Cat. Types Foss. Fishes,” p. 9,

Peecilodus angustus { gees } 1876. “Cat. West. Scot. Foss.," p 62,

Xystrodus angustus—J. J. Bigsby, 1878. “Thesaurus Devon.-Carb.,” p. 367.

Teeth, triangular, cuniform, length ‘9 inch, breadth ‘35 inch across the posterior
margin which is widest, the two sides converge anteriorly to an acutely-pointed,
recurved apex. The articular margin is prominent, rounded, and has a curvature
from front to back of considerable convexity ; the postero-lateral surface of the
crown is depressed, slightly concave, and terminates in a slight ridge forming the
postero-lateral margin ; the latter is straight and anteriorly curved downwards,
posterior margin slightly sigmoidal, crown surface is similarly punctated to that
of the previous species, though the arrangement in lines is not so clearly shown.
Base, thin compared with that of X. striatus.

It is possible this species may be the teeth of the upper jaw of X. striatus, both
are found in the same beds at Armagh, but until some evidence that such was the
relation they held is forthcoming, it may be better to regard them provisionally as
separate species.

Formation and locality: Mountain Limestone, Armagh.
£zx coll, Earl of Enniskillen.

4A2
''450 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

Xystrodus egertoni, Davis.
(Pl. LY., figs. 22, 23, 23a.)

Palatal teeth more or less rhomboidal and angular in outline, 1'1 inch in length,
‘4 inch in breadth towards the posterior portion. Anteriorly the teeth are slightly
convoluted with a broad termination. The articular margin is thick, prominent,
and elevated above the remainder of the crown, the remaining portion of the crown
is flat with a very slight concavity, posterior portion of surface much depressed ;
posterior margin forms an oblique angle with the margin of the articulating ridge.
Surface, closely covered with raised pustules, occasionally exhibiting a slight
tendency to arrangement in rows, the anterior part of the crown where most worn
exhibits a punctate surface as though the pustulated surface had been ground down
and a section of the dentigerous tubes exposed. Base very thick.

This species is at once distinguished from those collected at Armagh by the
angularity of its proportions and the very slight concavity of its coronal surface.
I have indited it to the memory of the late Sir P. Egerton, whose researches in
fossil ichthyology will ever serve as a fitting monument to his learning and a model
on which to base future investigations.

Formation and locality : Mountain Limestone, Bristol.
Ex coll, Earl of Enniskillen.

Xystrodus pulchellus, Davis.
(Pl. LV., figs. 24, 24a.)

Teeth, small, triangular, length °3 inch, anteriorly pointed, expanding posteriorly
to 15 of aninch. Surface of crown, concave, rising laterally to form a strong
rounded ridge on one margin whilst the opposite one is depressed towards. the
anterior extremity, but is raised slightly towards the posterior surface. Base
hidden. Coronal surface, beautifully marked by a series of transverse ridges
parallel to each other extending over the raised lateral ridge and disappearing as
they descend to the concave surface, which is smooth. On the opposite margin
there is a row of minute denticulations. The whole is uniformly and minutely
punctate,

This interesting little species is found in the limestone of Wensleydale, and
appears to be quite distinct from the species found at Bristol and Armagh.

Formation and locality: Carboniferous Limestone, Wensleydale.
Ex coll. Reed Collection, York Museum.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain, 451

Genus—Helodus, Agassiz.

«Sous cette denomination je comprends toutes les dents de Psammodus, dont la
surface est parfaitement lisse et le centre plus ou moins renflé en forme de céne
obtus. Ces dents sont tantdt allongées et arrondies avec un seul renflement au
milieu, tantét elles présentent une série de cénes obtus, dont celui du milieu est
plus élevé, tandis que ceux des cdtés vont en diminuant de grandeur, tantdt en fin
un simple céne plus ou moins saillant. Toutes les especes connus ont eté trouvées
dans les terrains houillers.”—(Agassiz, “ Poiss. Foss.,” t. 1, p. 104.)

Prof. Agassiz originally figured the species of the genus Helodus as belonging
to the genus Psammodus. The latter embraced al] those teeth whose crown
was composed of minute vertical tubes, and whose general structure bore a close
relationship to that of the Cestraciontes. The surface of the tooth was more or
less smooth, but punctate by the open ends of the pores of the crown, without
corrugations or striations, unreticulated and devoid of either crests or longitudinal
and transverse prominences. The discovery of an increased number of specimens
and the great variety of teeth included in the above definition led Prof. Agassiz to
divide the genus Psammodus into several others. They were as follows :—

I. Helodus.
II. Chomatodus.
III. Psammodus.
IV. Cochliodus.
V. Strophodus.

During the Geological Survey of Illinois, a number of new species of Helodi
were discovered, and amongst them some specimens which exhibited a close
relationship between teeth of Helodus and Cochliodus. The specimens are
described in the “ Palzeontology of Illinois,” Vol. IL, pp. 88-91, and consisted of
the upper and lower teeth of a large species of Cochliodus and a number of teeth
of Helodus ; in addition, the jaws are also preserved to some extent. The dis-
covery of any semblance of jaws with the teeth attached is an occurrence of such
importance that I venture, though rather lengthy, to give Mr. Worthen’s descrip-
tion in his own words, “ Fragments only of the jaws are visible on the specimens.
contained in the collection and such as are quite insufficient for determining their
form : they are now thin and flattened and much distorted, showing they had little
firmness or rigidity, and were, doubtless, for the most part, cartilaginous, though
it is possible in part ossified. They do not show a true bony structure, but
exhibit on fracture a fine granular composition, such as we have before seen

accompanying the more distinctly bony portions of the remains of cartilaginous

fishes, indicating, perhaps, a cartilage through which were disseminated innumerable

granules of ossific matter.

“The group of teeth
different forms, of which the surfac
are precisely the same throughout. These are,

impacted together includes at least four distinct and
e markings, microscopic structure, colour, &c.,
ist. Large, strongly enrolled teeth,
''452 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

marked with two strong, revolving ridges, separated by a deep furrow, which
correspond to the larger of the two teeth of either ramus of the jaw, figured by
Prof. Agassiz (‘ Poiss. Foss. Atlas, Vol. III., tab. 19, fig. 14), constituting the
type of the genus Cochliodus, and the tooth described by Prof. M‘Coy under the
name of C. acutus, Ag. (‘ Brit. Paleoz. Foss.,’ p. 621, Pl. 3 L., figs. 24, 25).. The
differences between these teeth and ours being only of a specific character,
2nd. A narrow tooth equally convoluted, and having a wedge-shaped outline
when seen from above, perhaps corresponding to the anterior pair in Agassiz’s
figure. This tooth has a single narrow and low revolving ridge, with numerous
obscure plications. 3rd. Teeth nearly as long as both the preceding. These teeth
are somewhat unlike any hitherto attributed to Cochliodus, and probably belcnged
to the opposite jaw from that which bore those before mentioned ; matching into
those when in use. If the teeth described by Agassiz and M‘Coy are, as supposed,
from the lower jaw, these are from the upper. 4th. Transversely elongated teeth
of smaller size, in diminishing series of size, joined by their longer sides, and in
some cases retaining their relative positions. These teeth have a more or less.
distinctly marked prominence or cone upon the crown, and an oblique and flattened.
root often as high as the crown, Considered by themselves, they would constitute
one or more typical species of Helodus,

‘They formed several rows, as is indicated by the differences which they present.

The enamelled surface of all these teeth, large and small, has a relatively
coarse porosity, precisely the same in all, and it is impossible to resist the conclusion
that they all formed parts of the varied dentition of a single fish. As they are
now thrown into a confused heap we can only conjecture what the relative position
of each form was. It seems probable, however, that the smaller conical teeth
(Helodi) formed several series intermediate between the larger and broader ones,
upon the symphysis of the jaw. In the living Cestracion we find a precisely similar
arrangement. ‘The rami of the jaws are covered with a series of broad, flattened
plates, fitted for crushing only, while the mesial portion of each jaw is occupied by
numerous rows of small pointed teeth, diminishing in size from front to rear.”
Whether the median teeth in the fossil Helodus (Cochliodus) were on a single row
or were common to both, Mr. Worthen was unable to determine. The specimens
were named Helodus (Cochliodus) nobilis, (N. and W.)

If the observations recorded above are correct, and there appears little doubt that
they are, the teeth, hitherto considered as distinct genera, are proved to belong to
fishes which had a somewhat complicated dentition, and a thorough revision of the
whole of the palatal forms of teeth may eventually be necessary. At present,
however, the grounds are so slight on which to raise such a fabric that it is im-
possible to more than hint at such a result, and to hope that ere long fresh dis-
coveries may serve to elucidate the true organization of the fishes that gave origin
to the fragmentary remains, which are all we now possess. In the fossil Helodi,
found in the Carboniferous rocks in Britain, there is little evidence to show either.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 458

the arrangement of the teeth, or whether they formed only a part of a larger series.
As almost always happens with the remains of the Elasmobranch fishes, the teeth
become detached and separated during the period of their decomposition, and it is
almost impossible to correctly infer any relation of one to another when found fossil,
under such circumstances,

Of the Helodi already described it is probable that several species, such as #H.
turgidus, were the median teeth of Cochliodus. This will also apply to most of the
America specimens. A second type, of which H. planus may be taken as an
example, has been proved to belong to a distinct genus of fish, and there is
no doubt so far as H. planus is concerned that it is the inside tooth of Psephodus
magnus. Capt. T. J ones, in a letter to Portlock, published in the Geological Report
of Londonderry, &c., p. 462 (1843), was the first to point out the relationship of i,
planus to Cochliodus (now Psephodus) magnus. He considered that the one passed.
into the other. Specimens in the Enniskillen collection show that the two teeth
were attached to each other in the same jaw.

It does not appear probable that any of the teeth of Helodus were associated
with those of Psammodus, or that the former stands in the relation of a subgenus
of the latter, as indicated by M‘Coy. There is no evidence of such near relation-
ship, and the general similarity of the porous surface of the teeth relied on by
M‘Coy, would indicate a relationship with several other genera, quite as reasonably
as with that of Psammodus.

Helodus crassus, Davis.

(Pl. LIX., figs. 1, 2) |
Psammodus cinctus (pars) —L. Agassiz, 1833. ‘Rech. Poiss. Foss.,” Vol. IIT., pl xy., fig,

13-21.
” 9 5 P. G. Egerton, 1837. “Cat. Foss. Fishes.”
Chomatodus _,, 4 L. Agassiz, 1838: 2." Rechs Poiss. Hoss.” Vol. TEf., po 107;

” ‘ J. E. Portlock, 1843. ‘Geol. Londonderry,” p. 467, pl. xiv.a, fig. 9.

in es A C. G. Giebel, 1848. “Fauna der Vorwelt,” Vol. L., pt. 3, p. 341,

- ce y H. G. Bronn, 1848. ‘Nomencl. Paleont.,” p. 292.

” ” ” ay 1849. “ Enumerator Paleont.,” p. 647.

” ys 4 J. Morris, 1854; ° ** Cat. Brit; Moss. p. o21.

5 i; li ci deter, 1854. “Traité de Paléont.,” Vol. IT., p. 266.

sg (enelodus),, 4, F. Moy, 1855. “ Brit.. Paleoz. Foss.,” p. 617.

” ees . Morris and Roberts, 1862. “ es Journ. Geol. Soc.,” Vol. XVIIL,
po.

” % » Enniskillen, 1869. © “Cat. Types Foss. Fish.,” p. 4.

45 * 5 Young and Armstrong, 1871. “Trans. Geol. Soc., Glasgow,” Vol. IIL,
Supt., p. 69.

. a i a ae \ 1876. ‘Cat. W. Scot. Foss.,” p. 60.

8 ‘ 3 J. J. Bigsby, 1878. ‘Thesaurus Dev.-Carb.,” p. 349.

» ” 2 L. G. de Koninck, 1878, “Fauna du Cale. Carb. de la Belgique,”

p. 46, pl. iv., fig. 3, pl. vi., figa. 1-5,
''454 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

Teeth, large, laterally elongate; outline irregular, length about double the
width, broadest in middle, tapering slightly and unevenly towards each lateral
extremity : length 1:2 inch; height of central cone ‘45 inch; breadth 6 inch,
diminishing at one lateral extremity to three-quarters, and at the other to half,
the greatest breadth ; the broader lateral extremity may be either to the right or
left of the central cone, Crown : central cone moderately elevated, laterally broad,
obtusely pointed: transversely somewhat beaklike, a ridge extends from centre of
the cone down each side, it is sinuous and slightly produced to form two or three
small minor cones, towards each lateral extremity. Posterior face, depressed from
the ridge of the crown to its posterior margin forming a deep concavity ; anterior
surface, convex; coronal surface, coated with thick, dark, beautifully polished
enamel, generally perfectly smooth, but in a few specimens covered with projecting
pustulate dots. Posterior ridge separating the crown from the base, broadly
expanded, margin concave. Anterior ridge, sinuously convex, broadly expanded.
Occasionally four or five concentric plicee extend along the anterior and posterior
ridges, but in the majority of specimens they are not present. Base; °3 of an
inch in depth ; laterally, equally extended with the crown, descending obliquely
from the posterior portion of the tooth, strong, fibrous in structure.

Helodus tenuis, Davis.

(El, LIX, figs. 3, 4.)

Chomatodus cinctus, Ag., pars.

Teeth, long, transverse section laterally much elongated, narrow, elliptical,
pointed at each extremity. Length to 1-0 to 1:2 inch, breadth, ‘3 to -4 inch, height
of central cone ‘35 of an inch. Crown: central cone, elevated, more or less sharply
pointed and thin ; anterior and posterior faces form a ridge at an acute angle
extending from the summit of the cone laterally in each direction and terminating
in an acute point. Ridge sometimes straight, in others sinuous; free from minor
cones. Anterior surface, convex. Posterior surface, deeply concave, summit of
cone recurved. Coronal surface, enamelled ; summit of ridge smooth, probably
with attrition during mastication, sides of ridge either coarsely punctate or pustulate,
Posteriorly a ridge separates the crown from the base, anteriorly the surface of the
crown is continued down into the base; there are no concentric folds. Base, °25
inch in depth, slightly produced anteriorly, rather more widely expanded than the
crown, strong and fibrous.

This tooth is easily distinguished from the species last described by its generally
more attenuated form and the acuteness of the coronal ridge, extending along the
centre of the tooth and its somewhat recurved apex.

This species was included by Professor Agassiz in the genus Chomatodus, but

the characteristic on which he lays greatest emphasis, the concentric folds near the
base of the tooth, are absent.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 455

Helodus clavatus, Davis.
(PL Ul fes.5,.6))

Teeth, long, club-shaped, sinuous in outline, broadly expanded at one end, tapering
to a fine point at the other. Length 1:2 inch, breadth ‘35 inch, height of crown
equal to the breadth. Crown, highest point occupies a position about one-third
the length from one of the lateral extremities: the summit forms a longitudinal
ridge, extending with a more or less sinuous convexity along the tooth, transversely
acuminate, the anterior and posterior surfaces expanding towards the base. From
the summit the ridge descends rapidly on the one side, ending in a slightly-expanded
obliquely-obtuse angle : on the other the descent is gentler forming an elongated
lateral prolongation, triangular in section, and terminating in an acute point.
Coronal surface, enamelled, punctate, or pustulate, on different specimens ; ridge of
crown, worn and smooth ; base, large and deep, not well preserved. There is no
evidence of concentric or other plice. Examples occur of what appears to be a
variety of this species. They have a general resemblance in contour and outline,
broadly expanded near one extremity, the other tapering and elongate, butin place _
of being raised to forma transversely acute cone, the crown is expanded and broad,
forming a comparatively depressed convex surface, the anterior and posterior margins
presenting a lenticular outline. Base not exposed. The coronal surface, as in the
specimens already described, is in some instances covered with small pittings, whilst.
in others, it is raised into small pustulate dots. The large extremity is either to
the right or left of the centre, showing in all probability that the teeth have been
arranged in at least two parallel rows.

Formation and locality : Mountain Limestone, Armagh,
Ex coll. Earl of Enniskillen.

Helodus acutus, Davis.
(PE LEX, fig. 7.)

Teeth, small, median tone large, equal in height to the length of the tooth,
which is ‘4 of an inch. Crown consists of a central cone, with a recurved lateral
and posterior basal margin. Central cone, obtusely pointed, a slightly angular
ridge extending from the apex down each side. Anterior surface slightly convex
transversely, slightly concave longitudinally ; posterior surface transversely rotund,
expanding towards the base. Basal portion of crown small, extending less than
half the diameter of the central elevation on each side, concave margin thick and
recurved upwards. Lateral recurvature extends posteriorly along the margin,
nearly to the median line, where the margin is depressed. Anterior margin and
base not exposed. Coronal surface deeply punctate, smooth at the apex.

Formation and locality: Mountain Limestone, Armagh. Unique specimen.
Ez coll. Earl of Enniskillen.

TRANS. ROY. DUB. S$0C., N.S., VOL. I. 4B
''456 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

Helodus richmondiensis, Davis.
(Pl. LEX, figs. 8, 8a.)

Teeth, small, median cone triangularly rotund, with slight lateral prolongation ;
diameter at the base ‘3 inch, height -2 inch. Crown abruptly elevated to a
prominent cone with a slightly acute apex; the anterior surface convex, with a
median ridge extending midway between the two lateral ones from the summit to
the base. Posterior surface deeply convex longitudinally, transversely rotund.
Posterior surface separated on each side from the anterior one by a well-defined,
straight ridge, descending from the apex of the cone to its base; one of the ridges
is prolonged at its base, and forms a lateral process extending beyond the median
‘cone. Coronal surface covered with enamel, uniformly and deeply punctate. Base
hidden by the matrix.

This tooth bears a close resemblance to Helodus simplex, Ag., from the coal
measures. The form of the central cone is similar, the principal difference con-
sisting in the absence in H. simplex of the well-defined and peculiar ridges
descending from the summit of the crown to the base. The lateral prolongations
of the crown in H. simplex are somewhat more extended than in this species,

Formation and locality : Carboniferous Limestone, Richmond, Yorkshire.
He coll. Harl of Enniskillen.

Helodus triangularis, Davis.
(Fl, LLX., fies. 9, 9a, 90.)

Teeth, transverse section approximately triangular and consisting of a single
cone. Height, -4 of an inch, about equal to the antero-posterior diameter and a
little less than the lateral diameter near the base. Summit of cone obtusely pointed
and slightly curved backwards. Anterior face convex, separated from the base by
a sigmoidal curve, the median part of it extending from the antero-lateral angles,
half the length of the tooth, towards the point. The anterior surface forms at its
junction with the posterior one angular lateral ridges extending from the apex to
the base. The posterior surface is doubly concave, with a wide and prominent
median projection separating it into two parts, and expanding towards the base so
as to render the form of the tooth almost that of a triangle. Encircling the base
of the crown there is a series of imbricating folds, very irregularly arranged. The
coronal surface, smooth, enamelled, or minutely punctate; where worn, near the
apex, the surface is occasionally roughly pustulate. Base not known.

This species approaches most nearly to the type of H. simplex, Agass., from the
coal measures, in possessing a single cone and comparatively small base, but it
differs materially from that species in its transversely triangular form, in its pointed
apex and the minute punctation of its enamelled surface.

Helodus richmondiensis is distinguishable from this species by the presence of a
well-defined process or ridge, extending from the apex along the median line to the
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain, 457

base, and also in the line dividing the base from the crown being straight, whilst in
_H. triangularis the line follows a deeply sigmoidal curve.

Formation and locality : Mountain Limestone, Armagh.
Ex coll. Earl of Enniskillen,

Helodus expansus, Davis.

(Pl) EEX fies 10, 10a.)
Chomatodus linearis (partim.) “Ag. Pois. Foss., Vol. III, p. 108, Tab. XII., figs. 5-13.

Teeth, medium size, quadrato-elliptical, length three or four times greater than
the breadth, very slightly broader in centre than at the sides. Length, 1°1 inch,
breadth in centre ‘35 inch. Height of central cone ‘2 of an inch. Crown, central
portion produced longitudinally to form an acute ridge, extending along the whole
length of thetooth; raised in centre to a moderately clevated broad gibbosity. On each
side, the ridge is slightly broken up into a number of minor very small projections ;
transversely the central cone and ridge are moderately thin, near the apex expanding
downwards to form a broad base. Anterior surface, convex laterally, and also from
apex to base of crown: three or four concentric imbricating folds extend parallel
with the anterior margin separating crown and base. Posterior surface, deeply
concave, widely expanded from the central ridge to the posterior margin, along
which there extends two, sometimes three, imbricating plicee. Lateral margins
anteriorly, rounded and obtuse, forming a right angle with the posterior margin.
The anterior and posterior longitudinal plicze are continued round the lateral margins
in close contiguity. Coronal surface, thickly coated with enamel, covered with a
very fine reticulation and minutely punctate. Base, equal in depth to the height
of the crown ; thin, deeply convex anteriorly, less so posteriorly.

This peeaiital species possesses the distinctive characters of Helodus ; the central
cone is less prominent than usual and the several minor cones presenting a
denticulated appearance seem to indicate a relationship with Ctenoptychius.

Formation and locality : Carboniferous Limestone, Armagh.
Fx coll. Earl of Enniskillen.

Helodus rudis, M‘Coy.
(PI. LIX, figs. 11, 11a).

Helodus rudis—F. M‘Coy, 1848. “ Annalsand Mag. Nat. Hist.,” 2nd Ser. Vol. IL, p. 123
=e 5 « 8 Morris, 1854. “Cat. Brit. Foss.,” p. 328.
rs 5 OB de Eee, 1854. “Traité de Paleont.,” Vol. FI., p. 267.
: i F. M‘Coy, 1855. “Brit. Paleoz, Foss.,” p. 631; Pl. 3.K., fig 2
- , Morris and Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol, XVIIL, p. 100.
a yr de de Bigeby; 1878. “Thesaurus Devonico-Carb.,” p. 357.

Teeth, “irregularly oblong, subquadrate ; sides, steep, irregularly uodulose, or
undulate-plicate ; crown irregularly gibbous, the highest point a little nearer one
end than the other; surface polished, coarsely punctured. Length, seven lines ;
width, four and a half lines ; height, two and a half lines,’-—‘Coy.

4B2
''458 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

The curiously irregular humplike figure and subquadrate form of the base of
this species distinguish it from its congeners; the ‘steep striated side is also
peculiar.

Formation and locality : Mountain Limestone, Armagh.
x. coll. Admiral Jones, Geological Society, London.

Genus Pleurodus, Agass., indet.

Teeth, small, triangularly or obliquely ovate; anterior extremity more or less
pointed expanding backwards, nodose median ridge extends along longer axis of
the crown, laterally thin ; margins more or less expanded and deeply indented
Surface covered with enamel; punctate, occasionally reticulate. Base thin,
coextensive with crown, hollow beneath.

The species hitherto described from British strata have been found only in the
Coal Measures. The horizon of the genus is extended by the discovery of the
species here described, downwards to the Mountain Limestone.

Pleurodus woodi, Davis.

(PI. LIX., figs. 12-15).

Teeth, small; length ‘3 of an inch; greatest width equal to the length ; more or
less triangularly-ovate in outline. Crown, convex ; laterally expanded ; median line
prominently developed to form a ridge extending across the greatest diameter.
Median ridge divided into five or fewer projecting nodes, from which lateral ridges
descend to the external margins ; these are terminally separated by deep indentations
of the margins; one end of the tooth, probably the posterior one, is wider and
somewhat rounded, the sides gradually taper to the opposite end. Surface of the
projections of the median ridge are frequently worn by attrition: uniformly and
somewhat coarsely punctate. Base or root thin, porous, conforms generally to the
outline of the crown ; proportionately concave to the convexity of the crown.

The teeth vary in outline, the anterior margins in some are deeply indented,
in others scarcely at all. A few specimens are very long in proportion to the
width.

In recognition of the services of the late Mr. Wood, of Richmond in Yorkshire, to
palzeontological science, I have pleasure in appending his name to distinguish these
teeth specifically.

Formation and locality :, Mountain Limestone, Richmond in Yorkshire.
Ex. coll. Reed Collection, York Museum ; Mr. Horne, Wensleydale.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 459

Group—Psammodontidee.

L. G. de Koninck.

Genus—Psammodus, Agassiz.

Teeth, large and flat, more or less rectangular in form ; root very thick, as large

as, and similar in form to, the crown.

Surface of the crown covered with small

pores, raised in rugose wrinkles or worn smooth ; surface of the crown sometimes

raised near one or both lateral edges.

Psammodus rugosus, Agass.

(PL LVI tee te 7 UV fos 1

Dens tritor rugosus—Miller MSS.
Psammodus rugosus—L. Agassiz,

rr

porosus 3
rugosus—J. E. Portlock,

porosus -
rugosus —L. G.de Koninck,

porosus y

-rugosus—C. G. Giebel,

porosus 5
rugosus—H. G. Bronn,
porosus 5

) 22

canaliculatus— F. M‘Coy,

rugosus—H. G. Bronn,
porosus—F, A. Quenstrot,
rugosus—J. Morris,
porosus 3
rugosus-—F, J. Pictet,

porosus 4
canaliculatus ,,
rugosus—F. M‘Coy,
»» Var porosus ,,
canaliculatus bs
porosus—F’, Roemer,

ps E. d’Eichwald,
rugosus—Morris& Roberts,
porosus a
rugosus—H. Rowanowsky,

porosus fe

1833.

1833.
1843.

9)

1844,

29

1848.

Wy

1848.

29

1849.
1848.

1849.
1852.
1854.
29
1854.

1854.

2)

1855.

Pr)

1856.

1860.
1862.

9

1864. °

“ Catalogue of Bristol Museum.”

“ Poissous Fossiles,” Vol. (iL, p. 111, pl,
xii, fig. 14-18 ; pl. xix., fig. 15.

‘‘Tbid,” Vol. TEL, p. 112, pl. xiit., fos. 1-16,

“ Rept. on Geol., Londonderry, &.,” p. 465.
p- xiv.a, fig. 1.

« Thid,” p: 4606, pl. xiv. a, Hg. 2.

“ Descr. des Anim. Foss. du Terr.-Carb. dela
Belgique,” p. 616, pl. liii., fig. 8.

“ Tbid;* p. 616, pl ty. tig. a 2

“ Fauna der Vorwelt,” Vol. I. pl. iii., p. 336.

“Ibid,” Voly Ls pl. ii. p 336.

“ Nomencl. Paleont.,” p. 1048.

“ Thid,” p. 1048.

“ Hnumerator Paleont.,” p. 647.

“Ann. & Mag. Nat. Hist.” 2nd Ser., Vol. IT.,
pote

‘‘ Enumerator Paleont.,” p. 647.

“‘ Handb. d. Petrefakt., p. 188, p]. xiii., fig. 61.

‘Cat. Brit. Foss.,” p. 341.

“ Ibid,” p..o41.

“Traité de Paléont.,” Vol. IL. p. 260; pL
Xxxvill,, fig 28.

“Ibid,” Vol. Isp, 266.

“Thids! Wel. diy p2e6:

“‘ Brit. Paleeoz. Foss.,” p. 644.

“ Thid,” p. 644.

“ Tbid,” p,,643; pl. 38 G, fig, 12.

“In H. G. Bronn Lethcea geogn.,” Vol. I.
p. 106; pl, ix, tig. 2,

“ TLetheea rossica,” Vol. L, p. 1547.

“ Quart. Jour. Geol. Soc.,” Vol. XVITI.,p. 101.

“Thid, Vou SVIlL. 101,

“ Bull. d. 1. Soc. imp. des Nat. de Moscou,”
p. 158, pl. iii., figs. 3 and 5.

“Thid,” p. 108, pl. il,, fig. 4.
''460 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britcan

Psammodus rugosus—Newberry and Worthen, 1866. “Geol. Surv. of Illinois,” Vol. IT., jo HOSS ol

x1, fig. 3.

ss porosus a 1000. 7nd Vo. 11., p.107, pl. xi, fig. 1.

mo reticulatus (1) es 1866," “Jind,” p. 109, pl. x1, fig. 9.

5 rugosus—Enniskillen, 1869. ‘ Alph. Cat. Type Fossil Fishes,” p. 7.

- inflexus ()—H. Trautschold, 1874. “ Fischreste aus dem Devon. des Gouver.
Tou, p. 11; pi. u.; ig. 12.

A porosus—F’, Roemer, 1876. “ Lethoea paleoz.,” pl. xlvii., fig. 2.

. % W. H. Baily, 1875. “Figs. of Char. Brit. Foss.,” p. 120, pl. xli,
fig. 9.

» 9 J. J. Bigsby, 1878. ‘Thesaurus Devonico-Carb.,” p. 365.

5 rugosus : - toabids aGo.

s canaliculus ‘, . 0D:

2 reticulatus 5 % 9 OOM:

5 porosus—L. G. de Koninck, 3 ‘Fauna du Cale. Carb. de la Belgique,” p.

41, pl. v., figs. 1-5.

Teeth, large, thick, more or less flat ; crown irregularly subtrapezoidal or oblong
in form, occasionally nearly rectangular, sometimes triangular. Anterc-posterior
margins sub-parallel, occasionally nearly straight, oftener concavo-convex. Convex
or anteriur margin shortest, One of the lateral margins generally straight, the
other oblique, forming a more.or less obtuse angle with the anterior margin, and
with the posterior margin extending backwards so as to form an acutely projecting
angle. Coronal surface hollowed in the middle, raised towards each lateral margin ;
or the central portion is raised or convex, in all probability indicating opposing
teeth. Entire surface covered with close sinuous ridges, roughly parallel with the
antero-posterior margins; in worn examples the wrinkles or ridges have been
rubbed down, either over a part or the whole of the surface, where it exhibits a
smooth, uniformly, and coarsely granulo-punctate surface, formed by the superficial
exposure of the openings of the medullary tubes. Root of the tooth varies in
thickness, usually inbevelled frora the crown, occasionally inbevelled in front and
on each side, whilst the posterior margin projects in a proportionate degree.

M. de Koninck (Fauna du Calcaire Carboniftre de la Belgique, p. 42) considers
that Psammodus porosus should be retained as the type, and describes the teeth
under that name; on the other hand, Prof. M‘Coy describes the specimens under
the title Psammedus rugosus, and as the unworn teeth all exhibit the characters
of the surface which led Prof, Agassiz to consider the species separate from P.
porosus, and the distinguishing characteristics of the latter are due to the grinding
action in using the teeth, it appears that the specific name selected by Prof. M‘Coy
should be retained. It has also precedence in the old Catalogue of the Bristol
Museum in which the teeth are styled Dens tritor rugosus. ;

The oblong form, in which the antero-posterior diameter greatly exceeds that
between the sides of the teeth, described by Prof. M‘Coy as a separate species
Psammodus canaliculatus, must also be included in the species P. rugosus. It
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 461

exhibits the same surface markings in unworn specimens as well as the smooth and
punctate eee where the rugose markings have been removed by trituration.
The rugosities in this form extend across the short diameter of the tooth, and if,
as appears probable, this form was placed lateraily alongside the larger specimens,
the rugose markings of each would lie parallel in the same direction. :

A reference to the figures on Plates LVI. and LVITI. will illustrate better than any
amount of description the varied forms assumed. by these teeth. The outline most
commonly observed is the one shown in Pl. LVL, fig. 1, a magnificent specimen
from the collection of Lord Enniskillen. The concave surface is the posterior
part of the tooth and was probably joined to another tooth; the anterior margin
is convex, the right side, which is the median line in the mouth, is straight, whilst
the opposite one expands obliquely backwards. In the accompanying figure, 1 b,
representing a section of the tooth, the crown is represented ‘2 of an inch in
depth, whilst the root varies from ‘4 to ‘6 in the central part, the lateral portions
being at the straight side ‘8 of an inch, and on the oblique or external side it is
l'Linchindepth. Prof. de Koninck (Fauna du Calcaire Carbonifere de la Belgique,
p. 42) has ventured an opinion that the teeth were arranged in three rows of four
teeth, each containing two of the broad teeth spoken of above, and on each side a
narrow tooth (the P. canaliculatus of M‘Coy). After very carefully studying
the large collection of specimens in the Enniskillen and other collections, it
appears very probable that a modification of this arrangement may have been the
one which existed. Prof. de Koninck remarks, ‘Je ferai remarquer que cette
derniére disposition n’est nullement hvpothétique comme ou pourrait le croire ;
je Pai observée sur une specimen de la collection de M. Neilson de Glasgow et
dont les trois dents conservées en place sont exactment reproduites par le dessin.
Il est done probable que pendent la vie de Vanimal ces dents étaient plus ou
moins mobiles et séparées les unes des autres par une légeére couche de matiére
cartilagineuse ou fibreuse.”

The form of the large teeth serves to confirm the opinions stated above, because
in every instance either the right or left lateral margin is straight, proving that
whilst the obliquely inclined margin conformed to the outer shape of the jaw, the
straight side Was adapted to fit the straight edge of the tooth on the oppesite ramus
of the jaw. In addition to the tooth shewn on PI. LVI., fig. 1, a less common
form is represented on Pl. LVIL, fig. 7, the diameter of which is twice or three
times greater between the antero-posterior margins than between the lateral ones,
and as stated the rugosities when present lie across the surface parallel with the
shorter diameter. The teeth are generally slightly curved, concave on the inner
margin, convex on the outer one; the outer postero-lateral angle is produced
acutely as in the larger teeth, and served to support the antero-lateral extremity of
the succeeding tooth. Examples of this form occupied the lateral extremities of
each jaw. A third somewhat persistent form is represented on Pl. LVIL, fig. 3.
It is similar to the last, except that its anterior margin is much contracted in
''462 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

width, almost reduced to a point and considerably curved inwards. It was
probably attached to the lateral margin of the first pair of dental plates, its
accuminate anterior extremity conforming to the curvature of the jaw.

There is still a triangular form (Pl. LVI., figs. 6,7) which has been found
abundantly at Bristol, but is less frequent, or absent, from the limestones of
Armagh. They may have occupied a position anterior to the large central teeth or
on each side the most anterior one. A diagrammatic representation of the recon-

| =)

structed jaw is here given from which the arrangement of the teeth indicated above
may be inferred.
An occasional tooth exhibits a more or less gibbous surface of the crown, this

appears to be an abnormal character, possibly due to some imperfection of the
corresponding tooth of the opposite jaw.

 

 

 

 

 

 

Group.—Copodontidz, Davis.

In the “ Poissons Fossiles,” Vol. IIJ., page 174, an undescribed tooth is named
Psammodus cornutus by Prof. Agassiz. The species is again referred to by
Portlock in the “Geological report of Londonderry, Fermanagh, Armagh,” &c., p.
466, and a figure is given of it (plate xiv.a, fig. 3). Portlock’s description consists
of some observations made by Captain Jones as follows: “ Several specimens have
been obtained where two teeth were in their natural position. The form is quite
distinct from that of its congeners; it is trapezoidal, having a long and a short
side, the long being more or less concave, the*short more or less convex, and, when
joined together, the convex side of the one tooth fitted into the concave side of
the adjacent one.” The specimen figured bears a great resemblance, to the figure
of Characodus angulatus to be hereafter described. Psammodus cornutus is again
''»

On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 463.

described by Prof. M‘Coy in Brit. Paleoz. Foss., p. 643, but no figure is given of
it. Itis described as trapezoidal: lateral sides long, straight, equal; posterior
side shorter than the lateral ones and concave; anterior side shortest, slightly
convex. This is the description of a tooth longer than broad, whilst the one
figured by Portlock is considerably broader than long.

In June, 1859, the late Prof. Agassiz visited this country, and devoted much time to
a re-examination of the large collection of palates trom the Mountain Limestone,
which form a conspicuous element in the collection of fossil fishes gathered by the
. Earl of Enniskillen.

The genus Psammodus amongst others received the attention of that skilled
Ichthyologist and the species P. cornutus was justly eliminated from the genus.
During the twenty years subsequent to the publication of the great work on Fossil
Fishes by Agassiz, numerous additions had been made to the collections of
Carboniferous Limestone fish remains, and consequently improved opportunities
for their study and determination were available. The teeth hitherto included in
the genus Psammodus, which were named P. cornutus in the “Poissons Fossiles” but
were undescribed, were discovered to be not only of distinct generic character, but
to represent more than one genus of fishes. Prof. Agassiz rearranged the several
specimens, and appended to them new generic and specific names, intending at
some future opportunity to publish descriptions and plates of them, with a general
revision of the whole group of fish remains from the Carboniferous Limestone.
Unfortunately this opportunity did not occurr, and the death of Professor Agassiz
has now rendered it impossible. The determinations and nomenclature of Agassiz
are here adhered to and retained, or when any change appeared necessary it has
been duly noted and explained.

The specimens comprised in the several genera indicated by Prof. Agassiz are
comparatively numerous in the Limestone quarried near Armagh; but notwith-
standing a few specimens have been obtained, they are very rare from other localities ;
a large majority of the species are represented by a fairly numerous set of examples,
and in no instance are they founded on unique specimens.

In some respects they approach the Psammodont group of fish palates, they were
more or less flat and pavement-like in their arrangement ; but as to the details of
that arrangement there is little or no evidence, The teeth of Copodus cornutus, Ag.,
which in many respects must be considered the type of the group, have been found
associated in pairs; they are very divergent in form. Whether, a large or small
number of teeth were implanted on each jaw is undetermined ; it is necessary to
await the advent of more complete examples, and should such be discovered, it is
quite possible that a considerable rearrangement of the genera and species which
are included in the group may be fund necessary. At the present moment the
genera appear well defined and established on a sound basis, but the whole course
of paleontological research has proved that the ideas conceived of genera and species

TRANS. ROY. DUB. S0C., N.S., VOL. I. 4C
''e

464 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

to-day, are greatly modified or completely changed by the discoveries of to-morrow,
that nothing can be regarded as fixed, and it is by the result of repeated applications
only that the palzeontologist is enabled to grasp the truth.

It is suggested that the whole of the genera presently to be described be regarded
as a separate group—the Copopontip#. In many respects they present features in
common and appear to form a natural group. The name of the most numerous,

best known and most characteristic genus naturally suggests itself as the fittest on
which to base the name of the group.

Genus Copodus, Ag., MSS.
Copodus—L. Agassiz, 1859. MSS. Enniskillen collection.
Palatal teeth of medium size, thick, sub-quadrate in outline; crown, either flat,
slightly convex, or slightly concave; enamelled surface uniformly punctate; anterior
margin convex, narrower than the posterior one; posterior margin, concave with

postero-lateral prolongations; base, same form as crown, strong, osseous, and
roughly striated.

Copodus cornutus, Agass. MSS.
(fl. EVIE, fies. 1-5.)

Psammodus cornutus—L. Agassiz, 1838. “ Poissons Fossiles,’ Vol. 111 ;p. 174.
Be J. E. Portlock, 1843. “ Rept. Geol. Londonderry,” &c., p. 461., Pl.xiva,
fig. 3.
5 e C. G. Giebel, 1848. <‘‘ Fauna der Vorwelt,” Vol. L., pl. 11, p. 336.
s 5 H. G. Bronn, 1848. ‘Nomencl. Paleont.,” p. 1048.
‘ fe 5 1849. ‘Enumerator Paleont.,” p. 647.
. 3 J. Morris, 1854. ‘Cat. Brit. Foss.,” p. 340.
F. J. Pictet, 1854, <“Traité de Paléont ,” Vol..IT., p. 266.
55 i F. M‘Coy, 1855, “Brit. Palos, Foss.,” p. 649,
Copodus cornutus—L. Agassiz, 1859. “MSS, Enniskillen collection.
a lunulatus ; 1859. % 3 ”
5) cornutus—Morris and Roberts, 1862. “ Quart. Journ. Geol. Soc.,” Vol. XVITI., p. 100,
Fe lunulatus . 1862. ms 33 55 a is
3 cornutus—Enniskillen, 1869. <“ Alph. Cat. Type Spec. Foss. Fish.,” p. 4.
" lunulatus s 1869. . ” ry
4 cornutus—J. J. Bigsby, 1878. ‘Thesaurus Devon. Carb.,” p. 351.
f lunulatus es 1878. 55 :

Teeth, sub-quadrate, anterior margin circular, lateral ones nearly straight and
increasing in breadth backwards, Average specimens ‘75 of an inch in length, and
about the same breadth between the latero-posterior augles, which are produced
beyond the posterior portion of the tooth in hornlike processes. Largest specimen
is 1:1 inch broad, posteriorly diminishing to ‘65 anteriorly. Length along the
median line ‘85 of an inch, along the side 1:15 of an inch. The same specimen is
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 465

-3 of an inch in thickness at a distance of one-third the length of the tooth from
the posterior margin and diminishes to ‘2 in front. Crown ; elther convex or con-
cave in each, presenting the appearance of having been considerably worn by
attrition towards the anterior extremity. The surface of the convex teeth are raised
in the centre and along each lateral margin with a slight lateral depression within
the margin ; the concave teeth are hollowed throughout with raised lateral margins.
Surface covered with a thick coating of enamel anteriorly, where much used and
worn the enamel is thin or quite removed; closely covered with minute punctures.
Anterior border circular, ganoine or enamel slightly projecting beyond the bony
structure of the base, and forming with the latter an acute angle, Laterally straight
or slightly convex, retreating towards the base. Posterior border concave with the
base projecting beyond the crown to give support to the anterior portion of. the
succeeding tooth. Latero-posterior angles produced in a line with the lateral margin
so as to form hornshaped extensions, widely separated by the posterior surface
of the tooth. Base; surface roughly striated longitudinally, slightly concave,
thickest in the centre and thinning off towards each side.

This species may be distinguished by the horn-like prolongations from the
latero-posterior angles, one-third or more of the length of the central axis of the
crown, they are continued in a straight line with the sides of the tooth, and are
widely separated from each other posteriorly.

A second palate was considered by Prof. Agassiz to constitute a separate species,
to which the name of C. lunulatus was given. The discovery of specimens with
Copodus cornutus, and C. lunulatus attached in such a position as to prove that
they are only one species, renders the latter species superfluous, and it is therefore
included in the former. 3

The second and smaller teeth are more or less crescentic in outline, anterior margin
circular, laterally much produced, posterior margin slightly curved or straight ; the .
length of the tooth is ‘35 of an inch along the median line, the breadth is °75 of an
inch. Transverse section, basal outline circular; greatest thickness in centre, ‘25
of an inch, tapering laterally to ‘12 of an inch. Crown, convex, oval in centre,
depressed towards lateral extensions, which are again raised. Surface covered with
enamel, profusely punctate, the punctures descending through the enamel to the
bony structure of the base. Anterior border, slightly circular, produced at each
side to form in conjunction with the more strongly curved posterior margin,
aliform lateral processes. The latter vary in size and form in different specimens,
in some obtusely rounded, in others acuminate. From the anterior and posterior
margins the base recedes, and is narrower than the crown, laterally the base
extends beyond the prolongations of the coronal surface.

The convexity of the anterior surface corresponds with the concave surface of
the posterior margin of the larger tooth, as shewn in the figure (PJ. LVIII,,

figs. 2,5). Both these surfaces exhibit considerable modification in form in different
402
''466 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

*
specimens, which, rendered necessary to the proper fitting of their respective
surfaces, affords an additional proof of the identity of the species.

Formation and locality ; Carboniferous Limestone, Armagh; tolerably common. Rare in the dark
Lower Limestone at Lowick (M‘Coy).
Ex Coll. Earl of Enniskillen.

Copodus furcatus, Agass. MSS.
(PL GVAL., fig.-16,)

Copodus furcatus—L. Agassiz, 1859. MSS. Enniskillen Collection.
5 falcatus (?)—Morris and Roberts, 1862. ‘ Quart. Journ. Geol. Soc.,” Vol. XVIIL., p. 100.
5; furcatus— Enniskillen, 1869. ‘Cat. Types Fossil Fish,” p. 4.
oe falcatus (1)—J. J. Bigsby, 1878. ‘Thesaurus Devonico Carb.,” p. 354.

Teeth, sub-quadrate, deeply forked posteriorly ; breadth, ‘8 of an inch, length,
‘9 of an inch from the anterior margin to the extremity of the fork; along the
median line to the point of bifurcation the length is ‘7 of aninch. Crown, convex,
with lateral margins raised, forming a slight, longitudinal concavity along each
side ; convexity in antero-central part much abraded by use. Posteriorly, the
coronal surface is depressed along the median line, prior to the bifurcation. The
surface is coated with enamel, and pierced by innumerable irregularly-disposed
punctures, Anterior margin straight in middle, with obtusely-rounded corners.
Laterally, the crown is nearly straight to the extremity of the postero-lateral
angles, where the diameter is slightly contracted. The postero-lateral are formed
by the posterior margin, which makes an acute angle with the lateral ones on each
side, and meeting in the median axis of the tooth, constitutes an approximate
right-angled bifurcation. Base equal in size and same form as the crown, charac-
terized by the ordinary structural appearance.

This species offers some resemblance to C. cornutus. The form of the
anterior portion of the tooth is very similar, but the posterior is quite distinct.
The bifurcation from the centre of the tooth in this species forms a specific
difference which cannot be mistaken. The pittings in the coronal enamel of

C. furcatus are less distinct, and separated by wider expanses of enamel than in
any other species of this genus.

Formation and locality : Mountain or Carboniferous Limestone, Armagh, Ireland.
Ex coll, Earl of Enniskillen,
''On the Fossil Fishes of the Carboniferous Inmestone Series of Great Britain. 467

Copodus spatulatus, Agass. MSS.
(Pl EV eit., fic. 7),

Copodus spatulatus—L. Agassiz, 1859. MSS. Enniskillen Collection,
Morris and Roberts, 1862. ‘Quart. Jour. Geol. Soc.,” Vol. XVIII, p. 100.
a Me Enniskillen, 1869. ‘Cat. Types Fossil Fishes,” p. 4.
os . J. J. Bigsby, 1878. ‘Thes. Devonico-Carb.,” p. 351.

Teeth, square, with rounded anterior angles ; at each postero-lateral angle there
is a wing-like projection from the body of the tooth, and at a distance of one-sixth
the diameter of the tooth isa suture parallel with the posterior margin. Length
of the tooth, ‘9 of an inch; breadth across centre of the crown, ‘8 of an inch,
diminishes anteriorly to ‘6 of an inch, and increases backwards to 1 inch. Trans-
verse section exhibits a convex base and slightly convex crown; greatest diameter,
°3 of an inch, thinning towards each side to a little more than ‘1 of an inch. The
thickness diminishes slightly towards the anterior extremity, and more so towards
the posterior. Crown, convex in central portion, with a raised broadly circular
rim, forming the lateral borders; anterior portion deeply excavated by attrition
during mastication ; posterior part of the tooth depressed and separated by a
distinct suture-like groove from the larger coronal area. ‘The latter is covered with
the usual minute pittings; the narrow posterior portion is less distinctly marked
and presents a reticulated surface. Anterior margin of crown straight in the
median portion, projecting beyond the extremity of the base ; antero-lateral angles
rounded, sides slightly convex, and expanded towards the back of the tooth into a
projection from the enamelled surface of the crown. The posterior margin for the
major part straight, each latero-posterior angle slightly produced and pointed
backwards. The latero-posterior expansions in this species are from the sides, whilst
in C. cornutus and C. furcatus they were developed from the body of the crown
backwards. In C. spatulatus the enamel of the coronal surface does not extend,
as in the species already described, so as to envelop the lateral expansion, but its
surface is rough, pertaining more to the bony character of the base. The
principal distinguishing feature, however, consists in the suture-like depression
running parallel to the posterior margin ; in no other species does this occur.

Formation and locality : Carboniferous Limestone, Armagh.
Ez coll, Earl of Enniskillen.

Copodus minimus, Davis.
(PL EV IIL, fies 8.)

Teeth, small, equilateral, angular, in general form differing from all the other
species. Length along the median axis, ‘4 of an inch; breadth across posterior
extremity, ‘35, diminishing gradually to the anterior, where the breadth is ‘2 of
aninch. Crown slightly convex from front to back, straight from side to side ;
''468 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

surface, enamelled and covered with irregularly disposed minute punctures.
Anterior margin straight or slightly convex; with the lateral margins it forms
obtuse-angled triangles; sides straight, widening to the junction with posterior
surface. Posterior margin slightly convex in the middle, depressed prior to its
forming the latero-posterior angles on each side. Latero-posterior angles acute,
extending a short distance beyond the general posterior surface, but not so
decidedly produced as in the previous specimens. Base hidden.

The teeth vary a little in size, the largest representative being °6 of an inch in
length. The crown in the larger specimens is much worn, and quite concave
towards the anterior margin.

This little tooth is more rectangular than either of the species described. In
form it more nearly approaches to C. cornutus, but it differs essentially from the
small or young specimens of that species; they possess the circular or convex
anterior margin, slightly rounded sides and well-developed posterior concavity, with
the horn-like prominences ; none of these characters, however, pertain to Copodus
minimus. The specimens are from the Mountain Limestone of Richmond, and
they are the only examples which have been found in that locality.

Formation and locality; : Carboniferous Limestone, Richmond, Yorkshire.
Ex. coll. Karl of Enniskillen.

Genus—Labodus, Agass. MSS.
Labodus—L, Agassiz, 1859. MSS. Enniskillen Collection.

Palatal teeth, medium size, more or less rhomboidal in outline, thick.
Crown, plain or convex, with a raised lateral margin, surface uniformly
punctate ; anterior margin straight or slightly sinuous; lateral margins convex ;
posterior well rounded; base much broader, but more contracted medially than
the crown ; thick, osseous, and extending beyond the coronal surface, so as to form
lateral extensions, culminating at the latero-posterior angles in diagonal projections,
higher and more prominent than the enamelled surface of the crown.

Labodus prototypus, Agass. MSS.
(el LVI, fies, 9-11.)

Labodus prototypus—L. Agassiz, 1859. ‘MSS. Enniskillen Collection.”
os - Morris & Roberts, 1862. ‘ Quart. Jour. Geol. Surv.,” Vol. XVITI., p. 101.
5 af Enniskillen, 1869. “Cat. Type Fossil Fishes.”
os 5 J. J. Bigsby, 1878. ‘Thesaurus Devon. Carb.,” p. 357.

Teeth, more or less rhomboidal in form ; breadth of enamelled portion of crown,
‘9 of an inch, beyond which extend lateral processes, giving a total breadth of 1:2
inches. The length of the crown along the median axis is 65 of an inch. Crown,
convex from anterior to posterior surface ; anterior half much worn by attrition,
and more or less concave in consequence. The central portion of the crown, ‘55 of
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 469

an inch in width, is convex. On each side this convexity, parallel with the lateral
margin of the crown, extends a flat groove, ‘1 of an inch in width ; beyond this
the surface is again raised, and forms prominent lateral ridges, as high or a little
higher than the central convex surface. The ridges form the boundary of the
coronal surface. Beyond the crown proper there is on each side a bold extension of
the bony ‘structure of the base along the whole lateral surface. Commencing with
a slight projection near the anterior lateral angle, they become gradually wider
and more prominent towards the posterior angle of the crown, where they are
developed into processes extending diagonally beyond the postero-lateral angle of
the enamelled surface to a distance of *25 of an inch, and standing at a higher ele-
vation from the base than the central convexity of the crown. Anterior margin
corresponds ina greater or less degree to the form of the crown, convex in the
centre, with depressions on each side, and a slightly prominent antero-lateral angle.
Lateral margin of enamelled crown convex ; osseous extension beyond this nearly
straight, with persistent expansion in breadth to the posterior angle; posterior
margin rounded, forming with the sides a more or less acute angle; surface of
crown uniformly punctate ; the minute orifices rather pentagonal than circular.
Base, breadth 1:25 inch diameter from back to front in central part; ‘4 of an inch
at each side, it expands to ‘6 of an inch. In its longest diameter the surface is
broadly convex, in the opposite direction concave ; greatest thickness, 8 of an inch
in the centre of the tooth; diminishes in each direction ; thinnest at the lateral
extremities, which are ‘175 of an inch in thickness.

The form of the base does not correspond with that of the crown, as will be seen
by a reference to the figures. The posterior circular portion of the crown pro-
jects considerably beyond the surface of the base ; and in the same manner, but to
a smaller extent, does the anterior margin.

The several teeth vary considerably in size and form, and their surface configu-
ration depends greatly on the amount of attrition to which they have been
subjected. The specimen selected for description is of average size, and its crown
in a good state of preservation. Examples occur in which the crown surface—i.e.,
the surface covered with enamel—is almost square in form, the average being
about one and a half times broader than long. A few specimens, seemingly derived
from very aged fish, are deeply worn, and present the appearance of three wide,
deep, longitudinal grooves—one in the centre and one on each side—with smaller
intermediate ridges, the front of the tooth very thin, and the anterior margin quite
worn away.

Formation and locality : Mountain Limestone, Armagh.
Ex coll, Earl of Enniskillen.
''470 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain..

Labodus -planus, Ag. MSS.
(Pl. VIE... figs. 12-14.)

Labodus planus—L. Agassiz, 1859. MSS., Enniskillen Coll.
6 5 Morris and Roberts, 1862. “Quar. J. Geol. Soc.,” Vol. XVIIL, p. 101.
5 » Enniskillen, 1867. “Cat. Type Speci.,” p. 5.
% 5 J. J. Bigsby, 1878. “Thesaurus Devon.-Carb.,” p. 357.

Teeth, more generally rounded in outline than L. prototypus, smaller, and the
lateral expansions of the osseous base less prominent. Length of crown along”
median axis, ‘7 of an inch, breadth ‘6 of an inch. Crown flat or very slightly con-
vex, ridge bounding the crown laterally slightly raised ; anterior part more or less
concave from attrition. Coronal surface covered with an exquisite arrangement of |
pittings, presenting the magnified appearance of the facets of a butterfly’s eye ; the
punctations increase slightly in size towards each side. Anterior margin slightly
concave, antero-lateral angles obtusely curved; lateral margins straight, expanding
a little towards the posterior aspect. Central part of the posterior margin convex,
with an incurving towards the postero-lateral angles, which are more or less pro-
minent. Base less constricted than in L. prototypus, between the anterior and
posterior margins, wider than crown ‘3 of an inch thick in centre, tapering near
each side to an acute angle ; transverse section convex, slightly depressed on each
side the median line; longitudinally the surface is concave. The base extends
beyond the crown on each side, but not to so large an extent as in L. prototypus, the
latero-posteriur angles are produced to the extent of “1 of an inch, or in some
instances rather more diagonally in continuation of the angle of the crown.

This species differs from L. prototypus in its evenly spread crown, round anterior
angles, and in the lateral prolongations of the base forming a less conspicuous mass
on each side the crown, as well as in minor details in the basal portion.

Formation and locality : Carboniferous Limestone, Armagh.
Ex coll. Earl of Enniskillen.

Genus.—Mesogomphus, Agass. MSS.
Mesogomphus—L. Agassiz, 1859. MSS., Enniskillen Collection.

Palatal teeth; outline tongue-shaped, posterior diameter equal to length,
narrowing towards the front. Crown slightly convex, depressed posteriorly with
a median well-defined semi-circular suture extending inwards from the posterior
margin ; lateral borders slightly raised ; coronal surface punctate. Anterior margin
circular, continued, and gradually expanding along the lateral margins ; posterior
margin convex, postero-lateral angles obtusely rounded. Base thick, transversely
convex, similar form to crown but extending beyond its posterior margin.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain 471

Mesogomphus lingua, Agass. (MSS.)
(PI EVIE, fig 16.)

Mesogomphus lingua—L. Agassiz, 1859. MSS., Enniskillen Collection.
5 a Morris and Roberts, 1862. “Quart, Journ. Geol. Soc.,” Vol. XVIII, p. 101,
: 3 Enniskillen, 1869. “Catal. Type Specimens,” p. 6.
_ 34 J. J. Bigshy, 1878. ‘Thes. Devonico-Carb.,” p. 359.

Teeth, General form, as indicated by the specific name, is tongue-shaped.
Length along the median axis ‘9 of an inch, greatest breadth at posterior portion is
the same as the length. The breadth gradually diminishes to the front, ending in
a rounded anterior extremity. Crown slightly convex in each direction ; lateral
borders raised ; anterior portion considerably worn by attrition, especially near
the extrémity. From the centre of the crown backwards the surface is depressed
towards the middle of the posterior margin, and a well-defined semi-circular suture
like depression extends from the posterior margin towards the centre ; the portion
of the crown separated by this suture, occupies rather more than the central third
of the margin, and extends ‘25 of an inch over the coronal surface, it is marked by
two or three transverse ridges extending across its surface; the whole surface of
the crown is minutely punctate. Anterior termination circular, gradually expanding
laterally towards the posterior margin, which is convex. Postero-lateral angles
obtusely rounded. Base thickest in the middle, thinner towards each side; from
the posterior to the anterior extremities about the same thickness is maintained ;
the form of the base is the counterpart of that of the crown. The enamel of the
crown projects anteriorly above the base, whilst posteriorly the base extends beyond
the crown, especially at each of the postero-lateral angles.

Formation and locality : Carboniferous Limestone, Armagh.
Ex. coll, Earl of Enniskillen.

Genus.—Pleurogomphus, Agass. (MSS.)

Pleurogomphus—L. Agassiz, 1859. MSS., Enniskillen Collection.

Palatal teeth: outline sub-quadrate, medium size, length and breadth
equal. Crown, concave, lateral borders slightly prominent, surface uniformly
punctate; posterior third of coronal surface depressed, lateral third on each side
separated by deep sulci or sutures. Anterior margin obtusely rounded, lateral and
posterior margins straight. Postero-lateral angles produced acutely. Base thick,
striated, longitudinally concave ; transversely convex extending slightly beyond the
lateral margin of:crown ; anteriorly and posteriorly shorter than crown.

In some respects Pleurogomphus bears a resemblance to Copodus cornutus, 1t has
the closely approximating outline of the coronal surface, but that of the base is
quite different ; in the latter the base is produced to form largely extended postero-

TRANS, ROY DUB. SOC., N.S., VOL. I. 4D
''472 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

lateral angles, and posteriorly the base extends beyond the coronal surface, appar-
ently to give support to a succeeding tooth. This is notso in Pleurogomphus ; the
distinguishing characteristic of the genus is in the division of the posterior area
into three parts by sulci, and in this it mainly differs from Mesogomphus in which
there is only one suture, and that a median one.

Pleurogomphus auriculatus, Agass. MSS.

CPA VETS tige, 15, 150, 150.)

Pleurogomphus auriculatus—L. Agassiz, 1859. MSS. Enniskillen Coll.
. - Morris and Roberts, 1862. “Quart. Jour. Geol. Soc.,” Vol. XVIIT., p. 101.
5 ; Enniskillen, 1869. ‘Catal. Type Spec.,” p. 7.
; J. J. Bigsby, 1878. “Thesaurus Dev.-Carb.,” p. 363.

Teeth, sub-quadrate in outline, rounded at the anterior angles; length, along
median axis, ‘75 of an inch; breadth, same as length. Crown, concave ; concavity
increased at the anterior portion by attrition; lateral borders very slightly raised.
Posterior third of the coronal surface is obliquely depressed, and on each of the
latero-posterior portions there is a circular sulcus or suture, very similar to the
median one uf Mesogomphus, except that in this genus there are two sutures,
cutting off or separating portions of the posterior surface at each corner, and leaving
the central portion connected with the crown, The sutures divide the posterior
margin into three equal parts, and extending longitudinally for a distance of about
‘2, of an inch, they curve in each case towards the lateral margins, to which they
approximate at ‘1 of an inch from the postero-lateral angle. The surface of the
separated portions is convex in front, the back portion receding. ‘The whole of the
coronal surface is punctate, and where not too much worn is coated with enamel.
On the anterior portion, where the enamel has quite disappeared, the punctate
character of the surface is still retained.. Anterior margin broadly circular ;
lateral margins straight. The enamelled surface forming the anterior margin
projects beyond the base. Posteriorly the margin is straight, except that each
postero-lateral border is produced, and forms an acutely-projecting angle. Base
thick, strong; longitudinally striated and concave; transversely it is deeply
convex, thinning towards each lateral margin, and extending slightly beyond the
crown. The posterior margin of the base conforms generally to that of the crown,
but like the anterior, does not extend so far as the coronal surface.

Formation and locality : Carboniferous Limestone, Armagh ; a unique example.
Ex coll. Earl of Enniskillen.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 473

Genus.—Rhymodus, Agass. MSS.
Rhymodus—L. Agassiz, 1859. MSS. Enniskillen Collection.

' Palatal teeth, transversely oblong, of medium size, the length less than half of the
breadth. Crown, convex in centre, laterally depressed, borders prominent. Coronai
surface, coated uniformly with enamel, slightly punctate. Anterior margin, deeply
concave, concavity occasionally occupied by a crescent-shaped portion of the
crown ; posterior and lateral margins convex, postero-lateral angles acuminate.
Base, thick, smooth, longitudinally shorter than crown; transversely convex ;
extending beyond the coronal margin, and forming an acute angle with the superior
surface of the tooth.

Rhymodus transversus, Ag. MSS.
(PE EVit is 1)

Rhymodus transversus—L. Agassiz, 1859. MSS. Enniskillen Coll.
o : Morris and Roberts, 1662. “ Quart. Journ. Geol. Soc.,” Vol. X VILL, p. 101.
a 5 Enniskillen, 1869. “Cat. Type Spee.,”:p.. 8.
:. i J. J. Bigsby, 1878... £¢Thes,  Dav-Carb, 7p. 36p-

Teeth, transversely oblong, thick, variable in size. Length of crown, °45 of an
inch ; breadth, ‘9 of an inch, beyond which an osseous prolongation of the base
extends *12 of an inch on each side, making the total breadth 1:14 inch. Crown
longitudinally and transversely convex in centre ; a depression extends across the
surface on each side, parallel to the lateral borders, which are raised and prominent.
Surface of crown, covered with enamel; uniformly, but indistinctly punctate.
Anterior margin of crown sinuous, central portion deeply concave ; antero-lateral
angles, obtusely rounded. Lateral margins convex ; posterior, well rounded in
central part, a depression on each side, corresponding to the one on the surface ;
postero-lateral angles slightly acuminate. Laterally, beyond the coronal surface
there is an extension of the osseous base, most largely developed at the postero-
lateral angles. Base, conforms generally to the outline of the crown, ‘3 of an inch
thick, transverse section, convex; thinning off laterally to an acute angle, with
superior face, longitudinally striated, smooth.

Figure 17 represents a specimen in which the deeply concave anterior surface
is occupied by an enamelled, crescent-shaped portion of the tooth, the division
being distinctly marked by the presence of a suture-like depression. The anterior
border in this specimen is straight.

Rhymodus oblongus, Davis.
(Pla LV-LE a tig,, 1.815

Teeth, oblong in contour; length less than half the breadth ; thickness
equal to length ; crown, convex in both directions ; lateral borders slightly

raised. A ridge, ‘15 of an inch in breadth, extends across the coronal surface
4D2_
''474 On the Fossil Fishes of the Carboniferous Limestone Serves of Great Britaan.

parallel to the sinuous margin of the anterior extremity of the tooth ; surface
thickly coated with enamel; rugose; folds extending longitudinally across the
crown. Lateral margin, crown extended beyond the base, concave in centre,
convex op each side, the convexity being continued to the lateral margins,
which, towards the posterior angles, are straight; posterior margin of tooth
straight ; postero-lateral angles, acuminate, slightly produced posteriorly. Base,
thick, osseous, striated, transversely convex, ‘95 of an inch across. Posteriorly the
base extends beyond the crown; laterally it is produced on each side of the crown,
forming aliform processes, widest near the postero-lateral angle, where they are “15
of an inch in breadth. Length of crown, ‘65 of an inch ; breadth, °3 of an inch.

This species differs from Rhymodus transversus in general form. The depres-
sions on each side of the crown and parallel to the border are not present, and the
lateral borders are much less prominent. The presence of the wide ridge parallel
to the anterior margin is also characteristic. The surface of enamel in &. trans-
versus is punctate; in &. oblongus it is longitudinally rugose, and the aliform
extensions of the base parallel with coronal surface are much wider in this species
than in the former one. ‘The two species agree in the deeply-concave anterior
margin, which in this species, as in &. transversus, afforded space for the attachment
of a secondary portion of the crown.

Genus.—Characodus, Agass. MSS.
Characodus—L. Agassiz, 1859. MSS. Enniskillen Coll.

Palatal teeth, more or less inversely conical in their outline, of medium
size ; crown, convex ; lateral borders produced, forming prominent ridges ; coronal
surface thickly enamelled, punctate, anteriorly worn by attrition, occasionally con-
siderably incurved over the base and crenated ; anterior and posterior margins
parallel, straight, slightly convex or slightly concave; lateral margins straight,
increasing in diameter backwards ; base, comparatively thin, similar in form to that
of the crown.

This genus comprises two species, the first of which, C. angulatus, must be taken
as the generic type. The second, C. cuneatus, whilst agreeing in all essential cha-
racters, is a considerably longer tooth than C. angulatus. Characodus may be
allied to the genera Labodus or Rhymodus. To each its transversely oblong form
bears a general resemblance; but a closer inspection exhibits peculiarities which
clearly separate it from those genera. The crown in Characodus is one-third less
in diameter anteriorly than posteriorly, and the base is co-extensive with the
crown, whilst the coronal surface of Labodus or Rhymodus is about the same
diameter anteriorly as} posteriorly ; but the osseous base extends in aliform pro-
cesses on each side, principally towards the back, beyond the lateral margin of the
crown, giving to those genera somewhat of the form and appearance of the crown —

of Characodus.

_
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 475

The genus Characodus may be distinguished from Rhymodus by the absence of
the deeply-concave anterior margin, and the crescent-shaped portion of the crown,
which is occasionally found occupying the concavity ; and from Labodus by its
concave or straight posterior margin and prominent base ; this margin in Labodus
being deeply convex, and extending considerably beyond the basal posterior margin.

Characodus angulatus, Agass. MSS.
(Pl. ‘LVIIL., figs. 19, 20.)

Characodus angulatus—L. Agassiz, 1859. MSS. Enniskillen Coll.
- Morris and Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. VALE, p29:
3 : Enniskillen, 1869. “Cat. Type Spec.” p. 3.
> 3 J. J. Bigsby, 1878. ‘Thesaurus Dev.-Carb.,” p. 349.

Teeth, trapezoidal in outline, medium size, posteriorly about an inch in breadth,
half an inch in length; crown, central portion longitudinally and transversely con-
vex. Fach lateral border is considerably raised above the central coronal area ;
surface coated with enamel and deeply punctured ; front part of the crown gene-
rally worn by attrition ; anterior margin two-thirds the breadth of the posterior,
straight or slightly convex ; lateral margins straight, augmenting in breadth pos-
teriorly ; the enamel and the osseous basal portion co-extensive, flat ; posterior
margin parallel to that of the anterior, straight or slightly concave ; postero-lateral
angles produced backwards in a line with the side, acuminate, raised prominently
forward. Base not well exposed ; retreats from the anterior margin of the crown,
and extends slightly beyond the posterior one. ‘the tooth is about °2 of an inch
thick.

Formation and locality : Mountain Limestone, Armagh,
Ex coll. Karl of Enniskillen.

Characodus cuneatus, Agass. MSS.
(PL LVI, fig. 21)

Characodus cuneatus—L. Agassiz, 1859. MSS. Enniskillen Coll.
% . Morris and Roberts, 1862. “ Quart. Jour. Geol. Soc.,” Vol, XVIELY ie 29:
u oe Enniskillen, 1869. “Cat. Type Spec.,” p. 3.
. +. dad, EABEy, 1878. “Thesaurus Dev.-Carb.,” p. 349.

Teeth, inversely conical or cuneiform in outline, ‘7 of an inch in breadth across
the posterior border, diminishing to ‘5 of an inch anteriorly. The length of the
tooth is 6 of an inch. Crown, longitudinally deeply convex ; the anterior portion
more curved than posterior ; transversely concave, the lateral borders produced,
forming ridges of unequal width; surface enamelled, punctate ; two or three broad
indistinct plications extend transversely across it; front part hollowed by attrition ;
anterior margin slightly concave; ganoine infolding base and crenate ; antero-
lateral angles right angles; lateral margins straight, crenulated, ganoine thick,
and infolding to some extent the osseous base ; posterior margin slightly convex ;
''476 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

postero-lateral angles obtuse. Base, not well defined ; does not appear to be large
or thick.

Characodus cuneatus is sufficiently distinct from C. angulatus; and, whilst pos-
sessing all the generic characters of the latter, its squarer outline, less produced
lateral borders of the crown, and the folding of the ganoine over the base on the
interior and lateral margins, and its crenated borders, vonstitute undoubted specific
differences.

Formation and locality : Carboniferous Limestone, Armagh.
£x coll, Earl of Enniskillen.

Genus.—Pinacodus, Ag. MSS.
Pinacodus—L. Agassiz, 1859. MSS. Enniskillen Collection.

Palatal teeth, small, more or less cuniformly oblong in outline. Crown, flat or
slightly curved. Coronal surface punctate or minutely rugose. Anterior margin,
concave. Lateral margins straight or a little convex, diverging posteriorly; posterior
margin convex (in P. gelasimus concave). Base not well exposed, moderately thick,
and co-extensive with the crown. :

A second tooth, smaller than the one described, was connected to its anterior
extremity, less than one-half the length of the larger tooth; its anterior and
posterior margins are convex, the latter closely fitting to the concave margin of the
first tooth ; surface convex, with raised lateral border, and conforming generally
to the shape of the crown of the adjoining one, front portion worn by attrition.

The genus Pinacodus is more closely allied to that of Characodus than any other,
and it is perhaps possible that the two genera may at some future time be shown
to have only specific differences ; the specimens at command do not afford sufficient
evidence of this close relationship to justify their amalgamation at the present
moment. The crown of Pinacodus is flatter than that of Characodus, and its
lateral borders less prominent; the posterior margin is convex in the one, concave
in the other, and in Characodus the anterior margin is not hollowed for the
accommodation of a second palate, which is perhaps the characteristic of greatest
generic importance in Pinacodus. .

The form of Pinacodus resembles that of Rhymodus in some respects, The
latter possesses a deep sulcus, separating a portion of the anterior face of the tooth,
which is probably a second tooth, as with Pinacodus. If this be the case, however,
the smaller anterior palate differs very much from that of Pinacodus. It does not
appear to have extended the whole breadth of the larger tooth, but becoming
laterally acuminate, to have ended before the margin was reached. ‘The basal
portions of the tooth of the two genera are quite distinct ; that of Pinacodus is
comparatively thin, and similar in shape and contour to that of the crown, whilst
in Rhymodus the base equals in thickness the length of the coronal surface,
and extends considerably beyond its lateral margin on each side.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 477

Pinacodus gonoplax, Agass. MSS.
(Pl LVIIL, fie, 22.)

Pinacodus gonoplax—lL. Agassiz, 1859. MSS. Enniskillen Coll.
“ Morris & Roberts, 1862. ‘ Quart. Journ. Geol. Soc.,” Vol. XVIII., p. 101,
y . Enniskillen, 1869. ‘ Catal. Type Spec.,” p. 7.
5 ss J. J. Bigsby, 1878. ‘Thesaurus Devonico-Carb.,” p. 363.

Teeth, sub-quadrate, slightly conical in outline, ‘6 of an inch broad, and ‘5 of
an inch in length, 16 of an inch thick. Crown, convex or concave in central part ;
convex teeth depressed on each side the convexity, the borders raised in all cases to
form prominent ridges. Coronal surface punctate or rugose. The anterior margin
in the majority of specimens is deeply concave, with antero-lateral angles, rounded
to a line with the lateral margin; lateral margin straight or slightly convex ;
posterior margin convex, upper part forming the angle with the coronal surface
constitutes a serrated ridge along the edge of the crown; postero-lateral angles
obtuse and rounded. Base not well exposed, but appears to be same form as
crown.

In one of the specimens there is a second smaller tooth attached to the
anterior margin described above, transversely elongated ; it is the same width as the
larger tooth, whilst its length is ‘15 of an inch only. Its surface is convex, with
raised lateral border, conforming generally to that of the adjoining one. The
anterior margin of the second tooth is convex ; posterior one convex, fitting closely
to the concavity of the larger tooth.

The arrangement of the two teeth forming this species affords confirmatory
evidence of the identity of the Copodus lunulatus with Copodus cornutus of Agassiz,
as previously stated in these pages. In this instance, as in Rhymodus transversus,
Ag., the second palate is situated at the front of the larger one, whilst in Copodus
cornutus the concavity is at the posterior margin of the tooth, and the second
palate was situated behind the larger one.

Formation and locality : Carboniferous Limestone, Armagh ; rare.
Lx coll. Earl of Enniskillen,

Pinacodus gelasimus, Agass.

(Pl. LVIIL, fig. 23.)

Pinacodus gelasimus—L. Agassiz, 1859. MSS. Enniskillen Coll.
iy = Morris and Roberts, 1862. ‘Quart. Journ. Geol. Soc.,” Vol. XVIIL, p. 101.
. ‘ Enniskillen, 1869. “Catal. Type Spec.,” p. 7.
‘i 5 J.J. Bigsby, 1878. ‘Thesaurus Dev.-Carb.,” p. 363.

Teeth, breadth double the length, posteriorly the breadth is ‘6 of an inch,
diminishing gradually to the anterior extremity where the breadth is -4 of an inch,
length ‘3 of an inch. Crown flat, with a slight convexity at the edges, a circular
''478 On the Fossil Fishes of the Carboniferous Limestone Serves of-Great Britain.

depression is worn from the anterior margin to within ‘1 of an inch of the
posterior one. Coronal surface enamelled, closely and deeply punctate. Anterior
margin, concave, lateral ones straight, diverging posteriorly. Posterior margin
concave, postero-lateral angles, acute. Base, thin but not well exposed. Unique
example.

This species differs from the former in having less prominent lateral coronal
borders, flat surface, and in the acuteness of the postero-lateral angles.

Formation and locality : Carboniferous Limestone, Armagh.
’ Ex coll. Karl of Enniskillen.

Genus Dimyleus, Agass. MSS.
Dimyleus—L. Agassiz, 1859. MSS. Enniskillen Collection.
Palatal teeth small, subquadrate; crown, convex; coated thinly with

enamel; punctate; transverse sulcus divides the crown into two parts, and
probably indicates two teeth. Anterior margin, convex ; posterior margin, con-

cave; lateral margins, constricted towards the transverse sulcus, otherwise straight.

Base, buried in matrix, extends slightly beyond lateral margin of the coronal
surface.

Dimyleus woodii, Agass. MSS.
(PL LVIIL, fig. 24.)

Dimyleus woodii—L. Agassiz, 1859. MSS. Enniskillen Coll.
5 e Morris and Roberts, 1862. “Quart. Journ. Geol. Soc.,” Vol. XVIIL., p. 100.
s 5 Enniskillen, 1869. “Catal. Type Specimens,” p. 5.
3 2 J. J. Bigsby, 1878. “ Thes. Dev.-Carb.,” p. 355.

Teeth, sub-quadrate, small, divided by a transverse depression or suture into two
parts. It appears very probable that there are two teeth but the whole of the
basal portion being embedded in the matrix, this cannot be satisfactorily ascertained.
Crown, convex, thinly coated with enamel, punctured, rather more coarsely towards
the border of the crown than in the centre. Anterior margin convex, lateral margin
straight, slightly depressed where the suture crosses the face; posterior margin

slightly concave; antero- and postero-lateral angles obtuse. A’suture-like depression
extends transversely across the crown dividing it into two unequal parts, the
posterior rather longer than the anterior. Total length *4 of an inch, breadth °35
of an inch.

This species received the designation Woodii in recognition and honour of
Mr. Wood, late of Richmond, an‘enthusiastic worker amongst the Limestone fossils
of his district, and to whom paleontological science is indebted for many important
discoveries.

Formation and locality : Carboniferous Limestone, Richmond, Yorkshire.
Ex coll. Karl of Enniskillen.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 479

Genus.—Mylax, Agass, MSS.
Mylax—tL. Agassiz, 1859. MSS. Enniskillen Collection.

Palatal teeth, broader than long. Crown, longitudinally convex ; transversely
flat, enamelled, rugose or punctate. Anterior margin, concave ; posterior
margin, convex ; lateral ones, convex. Palates succeeded each other on the same
plane, the convex posterior margin fittiag to the concave anterior one of the tooth
preceding it ; terminal tooth anteriorly convex. Base strong, with lateral processes
extending diagonally beyond the crown.

Mylax batoides, Agass. (MSS.)
(Pl. LVIIL, figs. 25, 26.)

Mylax batoides—L. Agassiz, 1859. MSS. Enniskillen Collection.
s “i Morris and Roberts, 1862. ‘Quart. Journ. Geol. Soc.,” Vol. XVIII, p. 101.
os Ma Enniskillen, 1869. “Catalogue Type Spec.,” p. 6.
i 2 J. J. Bigsby, 1878. <“‘Thes. Devonico-Carb.,” p. 359.

Teeth ; breadth ‘9 of an inch including basal projections beyond the crown;
breadth of single teeth °15, and of two together ‘3 of an inch. Crown divided into
two teeth, anterior one ‘55 of an inch in breadth, the posterior one ‘7 of an inch
in breadth: transversely, flat; longitudinally convex along the whole breadth.
Surface enamelled, rugose, with intermediate pittings. Anterior ‘margin concave
with obtusely rounded antero-lateral angles. Lateral margins convex ; posterior
margin convex in centre, hollowed towards each side and produced to form acute
postero-lateral angles. A suture separating the two palates extends transversely
across the specimen parallel with its posterior border, at a distance of -15 of an
inch. Base moderately thick, partially hidden by matrix. Anteriorly and pos-
teriorly it does not appear to extend beyond the crown, laterally, forms aliform
processes which extend diagonally -2 of an inch, at an angle of 45° from the latero-
posterior margin of the crown. In a second specimen, smaller than the one already
mentioned, the posterior palate is very much less than the anterior one, longitu-
dinally it occupies ‘1 of an inch, whilst the one in front of it is ‘2 of aninch. The
anterior margin in this instance is convex, and the anterior portion of the coronal
surface is considerably worn by attrition. It is probable that the convex
anterior tooth in this specimen is the terminal one, and that a similar palate origi-
nally occupied a position in front of the concave anterior margin of the specimen
first described.

The genus Mylax approaches more nearly to those of Dimyleus and Pinacodus
than to any others. In Pinacodus, however, the anterior palate is much smaller
than the posterior, the reverse of the case with Mylax. The latter is extremely
broad in comparison to its length, and the base extends in large processes beyond

the lateral margin ; in Pinacodus the crown and base are co-extensive, and the tooth
TRANS, ROX DUB, SOC., N.S., VOL, I. 4E
''480 On the Foss: Fishes of the Carboniferous Limestone Series of Great Britaw.

has a quadrate form. The Yorkshire genus, Dimyleus, appears to occupy an
intermediate position between those of Pinacodus and Mylax, both in form and
structure.

Formation and locality: Mountain Limestone, Armagh,
Ex. coll, Earl of Enniskillen.

Genus.—Mylacodus, Agass. MSS.
Mylacodus—L. Agassiz, 1859. MSS., Enniskillen Collection.

Palatal teeth, outline subquadrate, medium size. Crown; longitudinally,
slightly convex; transversely, central area convex; broad lateral depressions
with a slightly raised lateral border. Coronal surface thickly enamelled, punctate
or rugose. Anterior and posterior margins convex, lateral ones nearly straight ;
antero- and postero-lateral angles rounded. Base thick, transversely rounded,
deepest in middle, extends to, or a little beyond, the lateral margin of the crown,
anteriorly retreats slightly and has a compensating prominence posteriorly.

Mylacodus quadratus., Agass. MSS.
(Ph LVI. figs 27, 283

Mylacodus quadratus—L. Agassiz, 1859. MSS., Enniskillen Coll.
a ; Morris and Roberts, 1862. ‘Quart. Journ. Geol. Soc.,” Vol. XVIII, p. 101.
ns - Enniskillen, 1869. ‘Catal. Type Specimens,” p. 6.
9 “a J.J. Bigsby, 1878. “Thesaurus Devonico-Carb.,” p. 359.

Teeth : subquadrate, length °75 of an inch ; breadth ‘7 to °8 of an inch. Crown
more or less horizontal, longitudinally and transversely convex in middle area,
with a broad shallow depression on each side, and a slightly raised lateral border.
Anterior area generally considerably worn by attrition during mastication. In-
stances occur in which the whole central part of the crown has been worn
away. Coronal surface thickly enamelled, covered with an irregular arrange-
ment of pittings. Anterior margin convex, laterally almost straight, with
tendency to convexity ; enamelled edge of crown in some instances serrated ; pos-
terior margin convex, slightly broader than the anterior one ; antero- and postero-
lateral angles all obtusely rounded. Base ‘3 of an inch thick at the back of the
tooth ; ‘2 of an inch in front; longitudinally straight ; transversely rounded, thick
in the middle, thinning out towards each side, where the base projects slightly
beyond the coronal margin. In front the base retreats from the enamelled surface
with a slight concavity. Behind, on the contrary, the base projects slightly beyond
the enamelled surface.

This species is tolerably common at Armagh. The specimens vary in size from
the one described to palates not more than a quarter of an inch in diameter. They
also offer some variation in form. Examples occur in which the tranverse diameter
''“On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 481

is greater than the longitudinal; but all approximate, more or less, to a right-

angled outline.
Formation and locality ; Mountain Limestone, Armagh.
Ex coll. Ear] of Enniskillen.

Mylacodus sesamini, Agass. MSS.

(PI. LVI, fig. 29.)
Pinacodus sesamini, L. Agassiz, 1859. MSS. in the Enniskillen Coll.
Enniskillen, 1869. ‘Cat. Type Specimens,” p. 7.

Teeth; length, ‘6 of an inch, breadth, °7 of an inch. Crown, longitudinally convex,
worn by attrition on the anterior portion. Transversely, the central part is ele-
vated and flat, A considerable depression extends along each side the central
‘elevation, from which the surface again rises to form rather prominent lateral
borders. Coronal surface, enamelled, minutely and uniformly pustulately rugose.
The anterior margin is slightly convex, lateral ones having a slight convexity.
The posterior margin is deeply convex. All the angles are obtusely rounded ;
only a single specimen has hitherto been found ; the base is hidden by the lime-
stone matrix.

This species may be distingushed from M. quadratus by its more cone-shaped
form, and the decidedly rugose markings on the coronal surface.

The palate in the collection of the Earl of Enniskillen, named by Prof. Agassiz
Pinacodus sesamini, differs materially from the type of that genus. Its quadrate
form, rounded angles, and the arrangement of the coronal surface, separate it dis-
tinctly from the type of the genus Pinacodus. At the same time they indicate,
with equal certainty, its relationship to Mylacodus. 1 have, therefore, placed it in
the latter genus, retaining the nomen triviale, sesamin of Agassiz to distinguish it
from Mylacodus quadratus, Agass.

_ Formation and locality : Mountain Limestone, Armagh.

Ez coll. Ear] of Enniskillen.

Genus.—Homalodus, Davis.

Palatal teeth; outline more or less quadrate or trapeziform, medium
size, thick and strong. Crown fiat, lateral extensions unequal; coronal surface
enamelled, punctate, or reticulated ; anterior margin, convex or straight ; lateral
margins straight on one side, the other convex; posterior margin more or less
sinuous. One of the postero-lateral angles forms a considerable expansion from
the coronal surface, terminating in an acute angle. Base thick, slight convexity in
medium area of transverse section, concave on each side, longitudinally straight—
conforms generally in outline to that of the crown, smooth, fibrous.

The flat, pavement-like coronal surface of this species, combined with its irre-
gular contour, and the one-sided horn-like prolongation of the postero-lateral angle,
serve to render its character sufficiently peculiar, and to distinguish this genus

from all others.
4E 2
''482 On the Fossil Hishes of the Carbonifervus Limestone Series of Great Britain.

Homalodus trapeziformis, Davis.

(Pl. LVILL., fig. 30.)

Teeth: trapeziform, large and strong, 1°12 inch in length, anterior margin 1°1
inch in breadth, greatest breadth across the posterior extremity 1:5 inch.
Crown : flat, slightly bevelled towards the borders, depression in the left centre
worn out by attrition. Coronal surface covered with enamel, minutely and
irregularly punctate, the punctures towards the left lateral extension of the tooth
gradually disappear and a reticulated arrangement of the enamel takes their place.
Anterior extremity, convex ; the convexity extends without intermission along the
lett lateral margin forming a rude semicircle ; right lateral border, straight, the
angle formed by it with the anterior margin is a right angle. Posterior border,
slightly concave. Right postero-lateral angle slightly produced and acute. The
left pestero-lateral angle is much produced and extends °35 of an inch beyond the
posterior margin, forming with the semicircular extension of the anterior margin
an acute angle. Base not exposed. ,

Formation and locality : Carboniferous Limestone, Armagh. Very rare.
Lx. coll. Earl of Enniskillen.

Homalodus quadratus, Davis.
leh vii ic 31.)

Teeth : sub-quadrate in outline, length ‘8 of an inch, breadth in middle of tooth
the same, diminishing slightly anteriorly and increasing about the same amount
posteriorly. Crown, flat, with a very slight depression towards the left lateral
border. Coronal surface thickly enamelled, uniformly punctate. Anterior margin,
straight or very slightly concave. Lateral margin, straight, gradually diverging
posteriorly. Antero-lateral angles, obtusely rounded. Posterior margin slightly
convex. Lett postero-lateral angle produced and acute. The enamel of the crown
extends slightly beyond the marginal surface of the basal portion, and constitutes
two-fifths of the whole thickness of the tooth. Posteriorly the tooth is ‘25 inch in
thickness ; anteriorly this is diminished to ‘17 of an inch. Root, smaller than
crown but conforms generally to it in form. Transverse section, slightly convex
in centre, concave towards each lateral margin. Longitudinal section straight.
Surface, smooth, longitudinally striated.

This species may be distinguished from Homalodus trapeziformis by its square
form and the much dimininshed size of the left postero-lateral angle. The large
development of the left lateral extension of H. trapeziformis giving the whole of
the anterior and lateral margins a semicircular form, does not occur to nearly so
large an extent in H. quadratus, though it has similar distinctive features developed
in a minor degree.

Formation and locality : Carboniferous Limestone, Armagh. Very rare.
Ke colt. Earl of Enniskillen.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 483

Family : PETALODONTID&, Newberry and Worthen.

The genus Petalodus was instituted by Prof. Owen in 1840 (‘‘Odontography” p. 61,
pl. 22, figs. 3, 4, 5,), and considered a sub-genus of Psammodus, the crown of which
is produced into a median ridge and compressed, so that the ridge terminates the
contour of the crown, like a trenchant edge. In the type specimen from the collec-
tion of the late Sir Philip Egerton, the trenchant margin is slightly convex and finely
serrated, the crown is invested with a thin layer of dense enamel with a smooth and
shining surface, around the base of the crown the enamel is disposed in a series of
concentric lines which extend lower down on the posterior than on the anterior
surface of the tooth, and the enamel terminates on both sides in a line which is
convex towards the base of the tooth, contrary to the terminal contour of the enamel
in the compressed teeth of the sharks. The osseous basis of the tooth terminates
in an expanded obtuse convex margin. This lamelliform tooth is bent slightly
upon itself, so that a vertical section exhibits a slightly sigmoid flexure.

M. Agassiz recognized the genus Petalodus of Owen, and transferred his Choma-
lodus acuminatus to it along with several others (‘“ Poiss. Foss.,” Vol. III., p. 174,
footnote,) which were not described, but which he considered should form a family
separated from the Cestraciontes, because of the sharp cutting edge characteristic of
the teeth. The species included are the following :—

Petalodus acuminatus (Chomatodus). Yorkshire, Glasgow.
»  hastingsie, Owen (type). Armagh.

c psittacinus, Armagh.
e leevissimus. 3
rectus. i
. radicans. .
. marginalis.
i. sagittatus. .

The Petalodus rectus, Ag., is figured in the “Geol. Report of Col. Portlock,” tab. 14,
fig. 9, and in 1854 M‘Coy redefined the genus and described and figured the species
named by Agassiz as follows :—- (“ Palzeoz. Foss.,” p. 635, et seq.)

P. acuminatus, Ag. (+ P. rhombus, M‘Coy.)
P. hastingsize, Owen (+ P. levissimus, Ag.)
P. psittacinus, Ag.

P. rectus, Ag. (+ P. marginalis, Ag.)

P. sagittatus, Ag.

The remaining species named by Agassiz was elevated to form the type ofa new
genus Polyrhizodus magnus (=Petalodus radicans, Ag.) characterized by the base,
''484 On the Fossil Fishes of the Carboniferous Limestone Series of Great Brotaan.

which is simple and homogeneous in Petalodus, being divided into a variable num-
ber of distinct root-like lobes or fangs.

During the year 1858 Agassiz revised the Petalodonts in the Florence Court
Collection, and in addition to confirming the determination of M‘Coy with respect
to Polyrhizodus, he raised the species P. psittacinus, Ag., to form the type of a genus
Petalorhynchus. }

In 1866, Messrs. Newberry and Worthen published the following synopsis of
Petalodont genera (“ Geol. Survey of Illinois,” Vol. IL, p. 31) :—

Family, Petalodontide, Newb. and Worthen.

“Teeth compressed, transversely elongated, crown with anterior and posterior
surfaces enamelled, meeting above in a more or less acute-angled edge, bordered
below by imbricating folds of enamel, which encircle the crown; anterior crown-
face generally convex ; posterior concave; root more or less developed, sometimes
large, sometimes nearly obsolete, bony, rough, tumid.”

The family, Petalodontide, as defined by Messrs. Newberry and Worthen,
comprises the following genera :—

1. Petalodus—Owen.
P. hastingsiea—Owen (type).
2. Petalorhynchus—Agass. (gen. indet.)
P. sagittatus—Agass. (type, sp. indet.)
3. Ctenophychius—Agass.
C. serratus—Owen (type).
C. apicalis (Ag. indet.) (type).
4, Antliodus—Newberry and Worthen.
A. mucronatus—Newberry and Worthen (type).
5. Dactylodus—Newberry and Worthen.
D. princeps—Newberry and Worthen (type).
6. Polyrhizodus—M ‘Coy.
P. magnus—M ‘Coy (type).
7. Chomatodus—Agass,
C. linearis—Agass, (type).

To the above must be added :—

8. Ctenopetalus (Ag. indet.)—Davis.

C. serratus (Ag. indet.)—Davis (type).
9. Harpacodus (Ag. indet.)—Davis.

H. dentatus (Ag. indet.)—Davis (type).
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britaan. 485

The teeth comprised in the family Petalodontide as indicated in the list of
genera giver. by Messrs. Newberry and Worthen, “ Geol. Survey of IIl.,” Vol. IL.
page 31, present an extremely varied series, though each possesses the well-marked
features which characterize the family. There is in each genus a concavo-convex,
more or less sharply pointed petal shaped crown ; it may be broader than long as
in Chomatodus and several of the others, whilst in Petalorhynchus, though a great
variety may be observed in the form of the teeth, the prevailing form is that in
which the crown of the tooth is longer than its breadth. The roots of the several
genera also present a great variety of forms. In Petalodus and Petalorhynchus
the root or base is strong, tumid, and equalling the crown in length, whilst in
Aniliodus and Chomatodus the root is very small in proportion to the crown. In
Polyrhizodus and Dactylodus, the root is divided into a number of radicles. Not-
withstanding their general arrangement into the groups already named there is
no distinct line dividing the genera from each other, and intermediate forms may
be selected which combine some of the characteristics of one genus with those
of another and form connecting links which renders it almost impossible to break
up the series into well defined genera. Messrs. Newberry and Worthen had a due
appreciation of this difficulty, and remark that “if we could have for study the
entire organism now so dimly shadowed forth, in these numerous, variable, and
disconnected teeth, we should find in the form, in the complete dentition or in
other organs—the fins, the spines, the branchial openings, etc., characters by which
the group of fishes here represented might be arranged in a large number of well
defined genera, the community of form and structure which their teeth exhibit
would probably then be shewn to be a family, and not a generic character.” *

Having briefly reviewed the classificatory position of the Petalodonts, it is
proposed now to consider their relationship to other forms, fossil and recent, and
endeavour to deduce their zoclogical affinities, for this purpose a great help is
afforded by the genus Petalorhynchus.

The collection of Lord Enniskillen includes a large and magnificent series of
specimens of detached teeth of Petalorhynchus, varying very greatly in form and
size, so much so that without so large a series for comparison, it would have been
almost impossible to have comprised all the different forms under one specific head.
A detailed description of the teeth will be given in succeeding pages, and two or
three typical teeth are depicted on PI. LXL, figs. 12, 18, 14. In addition to the
numerous series of detached teeth, there is in the collection referred to, a number
of vertical rows or sets of teeth (Pl. LXI., fig. 16), and a single example showing the
horizontal or lateral arrangement (Pl. LXI., fig. 15). The latter example consists of
the crowns of three teeth, a central or median tooth, and two lateral ones. They
are undoubtedly in the same relative position they occupied in the mouth of the
living fish ; the crown of the central tooth is much longer than the ordinary form,

* “Geol. Survey Illinois, Palzont.,” Vol. BL) jop.3823
''486 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain

and proportionately narrower ; the teeth on each side are shorter, more acuminate
at the apex, and broader than the central one.

The vertical sets of teeth (Pl. LXL., figs. 16, 16a) are often in groups of five, occasion-
ally fewer. The smallest tooth is nearest the base, and was the one first used ;
the crown is about half the length of the tooth, which is half an inch. The second
tooth rises beyond it ‘2 of an inch, and is °3 of an inch across the crown. A third
and fourth tooth in succession have place before the newest and largest tooth is
reached. The breadth of the convex crown of the latter, though not well pre-
served, was ‘7 of an inch, and the total length from its apex to the basal extremity
is 1:4 inch. From the base to the apex, the series of teeth present on the anterior
face a uniform convexity, as represented in Pl. LXI., fig. 16a, whilst the opposite,
or surface inside the mouth is concave, and formed simply of the crown and
base of the longest and most prominent tooth, similar to the one represented
in’ PL LX, fig. 14.

The crowns of the lower teeth are circular, or very slightly pointed ; the upper
one, in use immediately prior to the decease of the fish, is pointed in the centre,
and in some instances is very long compared with the breadth, as in the centre tooth.
(Pl. LX1., figure 15.) It is probable, from the appearance of abrasion and wear of
the enamel along the crest of the crown, and for a little distance down the convex
face, that the lower teeth have each in turn occupied the primary position, and
having served their purpose have been replaced by new teeth, which have grown
or been raised up from the interior of the mouth ; the opposite to the method of
increase generally observed in Elasmobranch fishes. The apex of the crown of
each antecedent tooth is firmly pressed, and appears to become adherent, to the
imbricated base of the convex crown of the following one. The small teeth repre-
sent an early stage of the fish’s existence, and each succeeding one, larger than the
last, may indicate a more or less definite period, but certainly prove that as the
fish increased in size its dentition, and the consequent extent of the gape of the
mouth, also increased.

Having considered the vertical arrangement, there remains the further question
as to the lateral or transverse disposition of the teeth. Fortunately, a single spe-
cimen occurs in the collection which throws considerable light on this part of the
subject. It is a natural inference, from the arrangement ot the three crowns, illus-
trated in Pl. LXL., fig. 15, that the vertical series of teeth occupied a position side by
side in a horizontal row ; and, judging from comparison with other and existing
fishes, it is improbable that the entire series is represented by three teeth, but
rather that it was more extensive, and consisted of at least seven teeth. This is
rendered probable from the great resemblance existing between Petalorhynchus
and the Janassa described by Count Minster, to be further alluded to. Whether
seven was the number of teeth occupying each jaw at any given time or some other
was the number may be doubtful.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 487

near the basal extremity may have been separated one from the other, so as to
give a more expanded disposition to that portion of the teeth; but, that such was
the case is at any rate doubtful, because in the young fish, when only the smallest
or earliest set of teeth existed, they would extend in close contiguity round the jaw.
On the advent of the second set, their larger and broader crowns extended beyond,
and above the first, and so enlarged the surface and diameter of the gape. In the
same way, the further additions of the third, fourth and fifth rows constantly
increased the size of the mouth with the growth of the fish; and it does not seem
probable that the earliest teeth changed from their original position relative to each
other. It is also worthy of remark, that the majority of the vertical sets exhibit a
more or less bilateral arrangement, the lower teeth inclining to the right or left,
and having the appearance which would be presented if they had been placed at
the side of a central row, being inclined at an angle fitting them to occupy such a
position.

The teeth already described are in all probability the primary teeth of the lower
jaw. The primary or largest tooth of the central vertical series and the one in use
was longest, and proportionately more pointed than those on each side of it. It is
probable that the central primary tooth of the upper jaw was longer and narrower
than those of the lower jaw,and that thethree teeth represented in Pl. LXL., fig. 15, are
those of the upper jaw. In this example the length of the crown of the central tooth is
greater than one and a half times its breadth. It is pyramidally cone-shaped, and
converges to a bluntly-pointed apex. There are imbricating folds across the base
of the crown extending in parallel, slightly-curved lines, but not with the peculiar
sigmoidal curvature of the lateral teeth. ‘The base is proportionately very long
and strong—almost quadrate in section—composed of coarsely-striated osseous
tissue. The second, third, fourth, and fifth teeth succeed each other in diminish-
ing sequence, the smallest tooth being nearest the base. Their general character is
similar: the concave posterior surface of the crown of the second tooth rests on
the convex anterior surface of the one preceding it, and so on. The apex or cut-
ting edge of the crown in the secondary and succeeding teeth is, in almost all
cases, circular, and without the pointed apex of the primary teeth. This appears,

in all probability, to be due to those teeth having previously served as primaries,
and become worn during attrition, the most recent and largest teeth being those
in use. In each case the apex of one tooth rests on the imbricated folds of the
anterior coronal ridge of the preceding one, and must serve as a substantial support
to it. The whole series form a strongly convex mass. So close is the contact
between the lower basal portion of the series of teeth that their planes of division
appear to have become obsolete, and the whole anchylosed into one solid body. It is
difficult to say whether this be really the case; but where a set of the teeth have
become fractured, it is almost impossible to trace any division between them.

Whilst searching for affinities or relationship of this peculiar arrangement of
TRANS, ROY. DUB. SOC., N.S., VOL. & 4F
''488 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

teeth amongst recent or fossil fishes, a striking resemblance in some respects is
observed between it and the fossil genus Janassa of Miinster—(Beitriige zur Petre-
factenkunde, Heft V., p, 38, et seq.) Messrs. Hancock and Atthey have pointed out
the identity of Janassa with Climaxodus (M‘Coy) in the “ Nat. Hist. Trans. of North-
umberland and Durham,” vol. iii., p. 330. The teeth of both genera are described
as generically identical, “the differences being only those of proportion, there
being not a single character of importance to distinguish one from the other.”
“The teeth are depressed and elongated in the antero-posterior direction, and lapse
a little backwards. In form there is a wide concave margin, which standing up,
like a scoop or dredging bucket, is the cutting edge. Behind this the surface is
covered with transverse imbricated ridges, forming the grinding or crushing
portion; and further down, on a lower plane, the broad depressed root projects
backwards and downwards for a considerable distance. In profile they present a
sigmoid curve, the frontal scoop-like portion standing up in the direction of the
oral cavity, the posterior or root-extremity being turned downwards in the oppo-
site direction.” Both genera are described as possessing two kinds of teeth.
“Those already indicated may be looked upon as the principal or primary dental
organs; the other kind, or the secondary, in the two genera resemble each other
just as closely as do the primary ; and it is interesting to find that these secondary
teeth agree pretty closely with some of those included in the genus Petalodus of
authors, only they are oblique. The association of these Petalodontoid teeth with
the primary ones is too obvious to be called in question.” In Janassa the two
forms are actually found arranged in order, side by side, both in the British and
German specimens. The latter are from the magnesian limestone, the former from
the coal measures and mountain limestone.

The teeth are described as being arranged in the mouth “in slightly arched
transverse rows, the largest symmetrical primary tooth being situated on the
median antero-posterior line, and projecting a little in advance of the others, on
each side of this there are two similar teeth, but somewhat less, the outside one
being twisted obliquely ; the row is then terminated on either side by one of the
Petalodontoid form. There are therefore seven teeth in each row, including both
kinds—five primary, two secondary. Miinster represents five or six rows in close
succession from back to front, the teeth and rows gradually diminishing in size
forward. It is evident, then, that the arrangement of the buccal armature more
closely resembles that of the rays than the cestracionts or the sharks ; and indeed
notwithstanding the difference in the teeth themselves, in their arrangement they
agree in a remarkable manner with those in Myliobatis aquila and Zygobatis
marginata— a. relationship which was recognized by Agassiz. The largest teeth
are 13 inch in length, including the root, and $ inch wide at the broadest part.
Smaller side teeth are not more than ¢$ inch long and the petalodont secondary
teeth about 2 inch in length. The crown is fully two-thirds the entire length
''On the Fossil Fishes of the Carboniferous Limestone Serres of Great Britain. 489

and is divided into two portions, the anterior one occupies one-third the crown,
it is a wide, hoilow, arched, scoop-like cutting margin, which in some specimens
is obscurely and minutely crenulated or derticulated, and is usually quite sharp,
the second posterior part occupies two-thirds the crown, it is shield-formed, some-
what convex, with the point directed backwards and the sides evenly arched
outwardly. This portion is traversed by a series of strong transverse undulated
ridges imbricated forwards and divided by wide deep grooves, where the ridges
are much worn they are smooth, but where fresh they are rough or deeply
notched. The root is a wide plate as broad as the tooth and tapers slightly
backwards, behind it is rounded, convex above and concave below, and projects
backwards on a lower plane, the crown being elevated above its upper surface.
The lateral teeth are similar to the above, but they are inequilateral, one side
concave the other convex.

A comparison of the teeth of Janassa with those of Petalorhynchus exhibits a
great degree of similarity and also many essential particulars of dissimilarity.
The two genera agree in the quincunx arrangement of the teeth in the mouth, for
notwithstanding the circumstance that no example showing the complete
transverse dentition of Petalorhynchus has been discovered, still sufficient is known
to prove that the teeth existed in transverse rows, and the probability is that the
arrangement of the teeth in the two genera was uniform. That the vertical
arrangement was the same in each is amply proved ; there is in each a gradual
increase in size from before, backwards; the largest teeth being those in use, and
the smaller ones serving to support and strengthen them. The process of growth
or accumulation must have been the same in both species, each additional row
being superimposed from the inside, a method which is almost unknown amongst.
existing species of sharks or rays. The two genera differ much in detail, however,
in the form of the vertical sets of teeth; in J anassa, the group of teeth form a
thick mass, five or six teeth being equal in thickness to the length of the longest
tooth, whilst in Petalorhynchus the teeth are thinner, and so arranged as to form
a closed, dense mass, as firmly attached to each other as if they were anchylosed,
and the breadth is less than one-third the length of the largest tooth. The
coronal surface of the tooth in the two genera is divided into two parts, a
petaliform portion for cutting, and a second imbricated palatal surface, but the
relative importance of the parts is very different. The cutting surface of the tooth
of Janassa is small and the apex is simply circular, that of Petalorhynchus large,
longer than broad, and the central portion of the cutting edge, more or less pro-
duced and acuminate ; in the latter also the imbricated surface is small or absent and
does not appear to have served a very important part in the economy of the fish,
and the long root has been deeply embedded in the cartilage of the jaw. The
imbricated surface in Janassa is quite different, it occupies two-thirds of the crown

or about one-half the entire length of the tooth, and it was in constant use for the
: 4F3
''490 On the Fossil Mishes of the Carboniferous Limestone Series of Great Britain.

purpose of crushing and masticating the food of the fish. The teeth of Janassa,
formed not only a sharp cutting edge, but a large palatal surface extending
horizontally backwards along the floor and roof of the mouth. Those of
Petalorhynchus differed materially from this arrangement and constituted only a
sharp cutting surface; they appear to have been the teeth of a predaceous fish,
rather than of one which was a vegetable feeder as Messrs. Hancock and Atthey
argue that Janassa was.

Prof. Agassiz, who described and figuredthe Janassa of Miinster as Acrodus larva
(“ Pois. Foss.,” Vol. III.,p. 147, tab. 22, figs. 25-25), but afterwards recognised its
proper position and affinities (“ Op. Cit.,” p. 376), considered that Janassa was an
intermediate type between Myliobates and the Cestraciontes, and contributed to
bridge over the gap. between the rays and sharks, the limits of which appear
always less sharp in proportion as they become better known. Prof. Agassiz also
points out certain analogies between Janassa and Zygobates and Rhinoptera.

The dentition of the genera Myliobates and Zygobates possess several characters
in common. In place of pointed teeth they possess a series of dental plates, which
form a pavement-like covering attached to each upper and lower jaw: the teeth
are attached to each other by sutures, and extend in rows of seven teeth each,
from the front of the mouth far backwards towards the gullet. The chief
peculiarity of these teeth lies in the large development of the central plate, which
extends across the symphysis of each jaw ; it is larger in Mylobates than all the
remaining six teeth together. The latter are arranged three on each lateral
extremity of the central one. The central teeth of Zygobates are proportionately
not so large as those of Myliobates, the side teeth diminishing in size as they
recede from the central one. Both genera are represented by a few existing fishes
but are found fossil in large numbers amongst the Tertiary rocks. The teeth of
Janassa and Petalorhynchus are similar to, and agree with those of Myliobates and
Zygobates in the arrangement of the teeth in transverse rows, and in the position
of the central or medium tooth which covers the symphysis of the jaw: a
peculiarity which does not ordinarily obtain in the dentition of fishes, the teeth
usually occupying positions on, or in each ramus of the jaw but not extending
across, or otherwise connecting, the two rami. The latter feature, especially
considering its rarity, is remarkable, and it was from its occurrence in Janassa that
Prof. Agassiz derived the idea that the genus possessed affinities with the rays
How far he may be correct has not yet been demonstrated. The broad, ridged
teeth of Janassa with short horizontal crowns, adapted both for cutting and
crushing its food, bear a greater resemblance to the flat pavement teeth of
Myliobates, adapted only as a crushing or triturating surface, than do those of
Petalorhynchus. The teeth of the latter are pre-eminently cutting teeth, and
though a number of imbricated folds or ridges usually extend across them, it is not
probable that they were of the least service for masticatory purposes, the teeth
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain, 491

being in a position too nearly perpendicular to render the ridged surface
available. The teeth in both genera resemble each other much more than either
resembles Myliobates, and except in the fact of the central tooth in each extending
across the median division of the jaws, there could be little claim of relationship
between the sharp, pointed, cutting teeth of the one, and the flat, extended plates
of the other. In Myliobates and Zygobates each transverse row is composed of
seven teeth, a largely expanded median tooth with three angular-sided flat
surfaced teeth on each side-——a number which corresponds with that of Janassa,
and in all probability with that of Petalorhynchus.

From a careful consideration of all the external characteristics of Petalorhynchus
and comparison with those of Petalodus the conclusion must be reached, that they
possess generic features in common, and that whatever may ultimately be proved
to be the zoological position of one of them, will, in all probability, be found to
‘nclude the other. Whether this relationship will be found to extend also to the
varied genera which are included by Messrs. Newberry and Worthen in their
- definition of the Family Petalodontidee may be doubtful. The genus Janassa
(including Climaxodus, M‘Coy) which has been shown to possess characters closely
associating it with that of Petalorhynchus, will also be found to form one of the
same family. This appears to have been to some extent foreseen by Messrs.
Hancock and Atthey, who state that* “ Ultimately, perhaps, Petalodus will be
found to be more closely related than can at present be demonstrated (2.e., to
Janassa), for it is not only in the Petalodontoid form that a resemblance is
observed, but likewise in the primary teeth themselves, which show a remarkable
similarity in general form to some of the Petalodontes.” And in a second paper
“ On Janassa bituminosa, Schlotheim, from the marl slate of Durham’”t by Messrs.
Hancock and Howse, the concluding paragraphs are, “It is unnecessary here to
dilate on the affinities of Janassa. We may remark, however, that the full
investigation of the Permian Species has only the more confirmed our opinion of
its close alliance with the coal measure form (the so-called Climaxodus hingueforms),
and of a certain relationship of both to Myliobates and Zygobates. We may also
state that Janassa is more closely related to Petalodus than was at first thought ;
for we now find that the latter genus is provided with both symmetrical and
oblique teeth ; so that it is quite probable that they may be found to be arranged
in much the same manner as those of Janassa, especially as the former have been
found in vertical series, as previously stated.” ,

It thus appears that a close relationship exists between Petalodus of the
Mountain Limestone, Petalorhynchus of the Yoredale Rocks, Climaxodus from the
Coal Measures, and Janassa from the Permian Rocks, and that the latter, whilst
agreeing in the main with the genera of the older formations, also possess some

* “Op, Cit.,” p. 335. + “ Op. Cit.,” p. 356.
''492 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

characters which appear to ally them with the more recent genera Myliobates and
Zygobates of the Tertiary formations, whose representatives still exist, principally
inhabiting tropical seas. The fossil remains of the several genera are so
fragmentary, that it is extremely difficult to obtain sufficient data whereon to base
deductions of so great import as those above indicated. Of the older genera
Petalodus and Petalorhynchus absolutely nothing has been found except the teeth ;
and those only, except in very rare instances, as detached specimens. Along with
the teeth of Climaxodus and Janassa, masses of minute tuberculous shagreen have
been found associated. In a variety of the latter genus, described by Miinster as
Dictea striata (Beitrige zur Petrefactenkunde, tome ii., tabs. 3 and 4, fig. 1), the .
form of the whole body is indicated and is completely covered with fine shagreen.
The length of the fish is 0°390 metre, exclusive of the tail, the greatest breadth is
0:110 metre between the pectoral and ventral fins, the height of the head is
0:080 metre. The specimens obtained from the Marl Slates of Durham have also
associated with them masses of shagreen, and from the arrangement of the teeth,
it is inferred that the mouth was underneath the head as in the Elasmobranchi,
They possess an anal fin. The more recent genera Myliobates and Zygobates are
well known from their living representatives. The dentition forms a perfectly flat
mosaic-like pavement. The body is widely expanded, short, and comparatively
thin, and does not possess anal fins. It is more or Jess covered with tuberculated
shagreen. Occasionally a serrated spine exists in connexion with the dorsal fin.

The gradual change in the form of the teeth ; from the deeply-rooted, strong
sharp cutting teeth of Petalodus through various modifications in intermediate
genera to those of Janassa which combine the sharp cutting edge with a large
expansion of the base of the crown in the form of imbricated folds, adapted to
crushing alimentary substances, may have developed still further to form the
altogether flat teeth of the Myliobate rays, in which the cutting teeth have entirely
disappeared. The internal framework of all the fossil genera was composed of
cartilage and has entirely disappeared.

Genus.—Petalodus. Owen.
Ref, R. Owen, 1840. ‘“Odontography,” p. 61.

“Teeth transversely elongated, much compressed, thin, petal-shaped, cutting edge
serrated ; base of crown with several narrow imbricating folds of enamel, descending
lower on the posterior than the anterior face ; root large, oblong, thin, truncated.
below ; lower edge, obtuse, tumid.”
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Brita, 493

Petalodus hastingsize, Owen.

(PL, LES; figs: 16-24)

Petalodus Hastingsie—R. Owen, 1840. “ Odontography,” p. 61, pl. xxii., figs. 3, 4, 5.
e L. Agassiz, 1840. “Rech. sur les Poiss. Foss.,” Vol. III., pp. 174
. and 384.

»  levissimus, “ 1840. “Rech. sur les Poiss. Foss.,” Vol. IIL, pp. 174
and 384.

»  Hastingsii—J. E. Portlock, 1843. ‘Geol. of Londonderry,” &c., p. 468, pl. xiv.,
fig. 10.

»  levissimus, . 1843, ‘Geol. of Londonderry,” &c., p. 461.

- Hastingsie—O. G. Giebel, 1848, “Fauna der Vorwelt,” Vol. L., pt. 3, p. 345.

re leevissimus, ' os 1848. se a Vol. L, pt. 3, p. 345.

‘5 % H. G: Bronn, 1848. ‘‘Nomencl. Paleont.,” p. 949.

os Hastingsize, . 1848, 25% yy p. 949.

e . J. Morris, 1854. “Catal. Brit. Foss.,” p. 337.

levissimus—  ,, 1854. 5, Bh > Prods

a g F, J. Pictet, 1854. “Traité de Paléont.,” Vol. IL, p. 271. .

iy Hastingsie, ; 1854, oy VoloEhy pe 2uk,

» Hastingsii —F. M‘Ooy, 1855. ‘Brit. Paleeoz. Foss.,” p. 635.

Hastingsie—Morris and Roberts, 1862. “Quart. Journ. Geol. Soc.” Vol. XVIII, p. 101.

. leevissimus—  ,, fe 1862. a 5 is y  YOl-AVILL, p. 10a

ie 5 Young & Armstrong, 1871. “Trans. Geol. Soc., Glas.,” Vol. III., Supplt., p.74.

>,  Hastingsie—W. H. Baily, 1875.5 “Bigs. of Char./Br. Possils’ sp. 120, pl ain,
fig, 11,

levissimus—Armstrong, Young,
and Robertson, 1876. “Catal. of W. Scot. Foss.,” p, 62.

» Hastingsie—J. J. Bigsby, 1878. “Thesaurus, Dev.-Carb.,” p. 361.
4, leevissimus, 1878. % % s p. 361
De Koninck, 1878. “Fauna du Cale. Carb. de la Belgique,” p. 50,

j ‘ pl. Vif figs, 6; 7,8.

Teeth, “crown very thin, scale-like, gently convex along the upper edge,
turning abruptly downwards at the extremities; base of the crown with a broad
series of five or six imbricating folds of ganoine, towards which the crown slopes
without convexity downwards and outwards so that they form the thickest and
most prominent part of the tooth; they are arched downwards in the middle, but
abruptly curved upwards, and downwards again at the lateral fourth of the lengths ;
root abruptly narrowed, flattened, tongue-shaped, one third deeper than the crown
on the outer side ; surface highly polished, and smooth when perfect, the cutting
edge alone being marked with a row of punctures ; when worn, however, a fine
line extends from each of these punctures half-way down the crown, producing a _
striation scarcely visible to the naked eye.” —(M‘Coy). Average width of the crown
‘5 of an inch, height of tooth about the same as width of crown, of which the crown

occupies two-fifths. }
Specimens in the collections of Lord Enniskillen and others bear the nomen
''494-On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

riviale, P. levissimus, given by Prof. Agassiz to teeth of Petalodus which he at
one time considered distinct from P. hastingsie, further observation, however, von-
vinced that learned ichthyologist that they were modifications only of the same
species,

The teeth vary considerably in detail as to form, and occasionally examples are
discovered which appear to be considerably distorted, as in Pl. LIX., figs. 18, 20, in
which the root is deflected entirely to one side. These examples may have occupied a
position towards the posterior extremity of the jaw.

Formation and locality : Mountain Limestone, Armagh.
Lx coll, Earl of Enniskillen.

Petalodus acuminatus, Agassiz.

(Pl. LIX., figs. 22-24.)

Chomatodus acuminatus—L. Agassiz, 1833. “Rech. sur les Poiss. Foss.,” Wol. IIL, p. 108,
pl. Lxdes ios: 112, 13:
Petalodus acuminatus— cs 1840. “Rech. sur les Poiss. Foss.” Vol."IIL, pp. 174
; and 384.
s ss J. E. Portlock, 1843. ‘Geol. of Londonderry,” p. 461.
is 33 C. G. Giebel, 1843. ‘Fauna der Vorwelt,” Vol. L., pt. iii., p. 345.
s Hi H. G. Bronn, 1848. “ Nomencl. Paleont.,” p. 949.
3) rhombus— F. M‘Coy, 1848. “Ann. and Mag. of Nat. Hist.,” 2nd ser., Vol.
1p, 125;
es acuminatus—H. G. Bronn, 1849. “Enumerator Paleont.,” p. 646.
ys J. Morris, 1854. “ Catal. Brit. Foss.,” p. 337.
5 ss F. J. Pictet, 1854. “ Traité de Paléont.,” Vol. IL., p. 271.
o 5 F. M‘Coy, 1855. ‘Brit. Paleozoic. Foss.,” p. 635, pl. il. G, fig. 4.
a rhombus, os 1855. a ra - p. 635.
3 acuminatus—Morris and Roberts, 1862. ‘Quart. Jour. Geol. Soc.,” Vol: XVIIL., p. 101.

= e J. J. Bigsby, 1878. “Thesaurus Devon.-Carb.,” p. 361.

Teeth, “Crown sharp, compressed, anterior face of variable height, regularly
rhombic, the upper and lower margins sometimes symmetrical, the lateral portions
of each being nearly straight, or slightly arched downwards, and meeting in the
middle at an obtuse angle, or, more frequently, the angle both of the apex and
coronal ridge more or less rounded. The cutting edge is obscurely undulato-dentate
in some specimens by short obsolete vertical furrows, and minutely crenulato-
striated, more commonly without the vertical plicee, from the faint undulations of
the edges. The lower margin is prominent, and surrounded by five or six small
imbrications of ganoine. These descend lower (as usual) on the posterior face,
where also the mesial angulation is less ; surface smooth, with a few fine irregular
longitudinal striz ; root moderately large.” Height of the middle of the crown ‘9
of an inch; width of crown 1°5 inch; depth of root 1:2 inch. ‘he proportional
height and size of the crown compared with that of the root is very variable.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 495

The specimens figured are from the collection of the Earl of Enniskillen and the
Reed collection at York. In each case they have been obtained from the same

locality, near Richmond, in Yorkshire. :
The fine specimen, represented on Pl. LIX., fig. 22, exhibits a peculiar form

of the root, which is deeply grooved in a longitudinal direction, and appears to
approach, in some degree, to the divided root of Polyrhizodus. In the same speci-
men the folds which encircle the base of the crown are united, and form a single
prominent overlapping plication.

Formation and locality ; Mountain Limestone.
Ex coll. Earl of Enniskillen, and Reed Collection, York Museum.

Petalodus rectus, Agass.
(Pl. UX fe 2)

Petalodus rectus—L. Agassiz, 1840. “Rech. sur les Poiss. Foss.,” Vol. III., pp. 174 and 384,
Pe J. E. Portlock, 1843. ‘Geol. of Londonderry,” &c., p. 461, pl. xiv., fig. 9.
i 3 C. G. Giebel, 1843. ‘Fauna der Vorwelt,” Vol. I., pt. 3, p. 345.
- S H. G. Bronn, 1848. “Nomencl. Paleont.,” p. 949. .
= ‘ > 1849. ‘“ Enumerator Paleont.,” p. 646.
- \ J. Morris, 1854, “Cat. Brit. Foss.,” p. 337.
in 3 F. J. Pictet, 1854. “ Traité de Paléont.,” Vol. II., p. 271.
os a F. Moy, 1855. “Brit. Paleeoz. Foss.,” p. 636.

Young & Armstrong, 1871. ‘“ Trans. Geol. Soc. Glasgow,” Vol. III., Supt., p. 74.

Armstrong, Young,
and Robertson, 1876. “Cat. of W. Scot. Foss.,” p. 62.

Teeth : “ Very broad, greatly flattened ; crown thin, rectilinear, or nearly so ; in
some specimens slightly undulated, and marked with vertical striz near the edge,
in others, crown surrounded by a broad band of four or five imbricating lamellee
of ganoine; root deeper than the crown and coronal folds together, concave in its
upper half, tumid and longitudinally rugged below. Average length of a rather
small specimen 1 inch; height of crown 1 line, width of coronal bands line, depth
of root 24 lines. The width and slight elevation of the knife-like crown of this
species easily distinguish it from any others. The name of P. rectus of Agassiz’s
published lists applies to the perfect, nearly straight-edged specimens, while his
name P. marginalis applies to the slightly-worn examples, in which the edge is
striated and undulated, and I have traced the perfect passage of one form to the
other.’ —(M‘Coy.)

This species is figured by J. E. Portlock, in the ‘ Geological Report of
Londonderry,” &c., pl. xiv., fig. 9. It approaches very nearly in form to the genus
Chomatodus, as defined by Messrs. Newberry and Worthen (“ Paleont., Illinois,”
Vol. IL, p. 34), excepting the root, which is well developed, and petalodont in

character.

Formation and locality : Carboniferous Limestone, Lowick.

TRANS. ROY. DUB. SOC., N.S., VOL, I, 4q@
''496 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

Petalodus grandis, Davis.
(PX. ig. 1)

Tooth, this is in several respects the largest and strongest member of the group.
It is 2°5 inches across the crown. The depth along the central axis of the tooth
from the tip of the crown to that of the base is 2inches. The centre of the coronal
surface is highly convex; on each side the convexity gives place to a propor-
tionately deep concavity, the lateral tips of the crown are again raised and stand.
prominently forward. The convexity and concavity of the surface are reproduced in
the crest and anterior margin °8 of an inch apart, bounding the coronal surface, and
give to them sinuous outlines which converge to form a pointed extremity on each
side. The junction of the anterior and posterior surfaces of the crown form a crest
at an acute angle, with an undulating outline independently of the sinuous one
already mentioned. The surface of the crown, where not worn or broken, is covered
with enamel, pitted near the basal portion, and, in its higher part, striated and
ductiferous. Where the internal portion is exposed by a broken surface, the bony
structure with innumerable canaliculi is easily distinguishable. The anterior median
ridge is broad, prominent, smooth, and devoid of inferior foldings; as already
observed it follows the sinuous outline of the surface of the tooth. Beneath the
ridge the anterior surface of the root gradually retreats and becomes, in conjunction
with the posterior surface, somewhat thin and acuminate, from the lateral
extremities the base of the tooth becomes gradually ‘contracted and terminates in a
widely rounded extremity. The base or root is simple and undivided. Its surface near
the anterior ridge is longitudinally furrowed, but the furrows disappear lower down.
and the base becomes even and smooth, thickest in the middle and thinning off on
each side, and forming an acute angle with the opposite surface.. The anterior face
of a second specimen is exhibited. ‘The antero-coronal ridge is produced in front
retreating on each side and much depressed at each lateral extremity, the surface
is generally convex, the posterior border evenly circular. The centre of the crown
is worn in front. From the anterior ridge the basal portion retreats slightly,
forming an unbroken root.

This magnificent specimen bears a close relationship to the species of the genus
Polyrhizodus found in the same locality ; in every respect except the division of the
base into several rootlets, the characters of the two genera are similar. The largest
species of Petalodus hitherto described is P. destructor N. and W. (“ Geol. IIl.,”
Vol. Il, p. 35., pl. ii, figs. 1, 2), from the coal measure limestones of Ilinois ; it is
smaller in size than the species now described, considerably longer in proportion
to the breadth, and both the crown and lower portion of the base are much more
acuminate than in Petalodus grandis.

Formation and locality ; Mountain Limestone, Armagh.
Ez coll. Earl of Enniskillen.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britaan. 497

Petalodus recurvus, Davis.
(PL ioe, fie.2.)

Teeth, medium size. Crown, very broad, nearly twice the breadth of the base as
well as of its length ; anterior face, laterally circular, vertically concave; apex,
circular, minutely serrated, sharp ; coronal ridge prominent, with two or perhaps
three somewhat indistinctly imbricated folds of ganoine. The width of the crown is
1'4 inch, greatest height in centre ‘35 of an inch ; from the centre, the coronal ridge
by a sigmoidal curvature, approaches towards the apical circumference, the lateral
extremities are curved considerably towards the base and end in an acute point.
Posterior surface not visible, embedded in matrix. Root, rapidly contracted from
the width of the crown to one half its diameter, it is ‘4 inch in length, roughly
fibrous, convex, laterally depressed.

This species is marked with considerable distinctness from any other British
species, neither does it approach near to any of the American ‘forms. It differs from
P. acuminatus, Agass., in its greater breadth of coronal surface compared with its
depth, the roundness of the cutting edge, which in P. acuminatus is pointed in the
centre. The crown is also much less pointedly produced along the anterior median
ridge. The root is shorter, thicker, and has a circular termination.

In general form this species is similar to P. linguifer N. and W. (“ Palzon. Ilinois,
Vol. IL., p. 87, pl. ii., figs. 4, 5), but may be easily distinguished by the lateral extremi-
ties of the crown, which in this species are curved towards the basal portion and
acuminate, whilst in P. linguifer they are rounded and terminate without curvature

towards the base.

>

Formation and locality : Mountain Limestone, Bristol.
Ex colt, Earl of Enniskillen.

Petalodus inequilateralis, Davis.
(PIER, tes. 3,4)

Teeth, length 1'2 inch, height °55 inch; coronal surface, broad and short,
indefinitely sinuous. Base nearly as wide as crown and twice its depth. Crown,
anterior surface, expanded on one side the median line to twice the height of the
opposite one. The wider half terminates in a rounded extremity without
depression, whilst the narrow one is curved towards the base and terminates
acutely. Cutting edge, generally much worn or minutely serrated. Coronal ridge
somewhat prominent, bearing three or four imbricated ganoine folds, extending
across the tooth with a doubly sigmoidal curvature. Posterior surface, deeper
than the anterior, but taken up in great part by eight or ten foldings of the surface,
so that the smooth portion is less in vertical extent than that of the anterior
surface. The form of the posterior portion of the crown conforms generaily to

that of the anterior one, at the broad end its height is ‘85 inch, at the narrow one
4G2
''498 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

it is only ‘2 inch, the imbricated folds occupy nearly three-fourths of its surface.
Anteriorly the crown is covered with a coat of dense enamel, through which the
dentigerous tubes do not appear to penetrate unless it be at the apex, along the
serrated edge they may be distinctly seen where the serrations are worn off. Root,
anterior surface, from the ridge is depressed and concave, lower portion convex
roughly fibrous, posteriorly it is convex and rounded with a number of vertical
ridge-like prominences. The root conforms to the general shape of the crown, it
is deepest on that side on which the crown is highest, and in the opposite direction
gradually converges and meets the coronal surface, forming a slightly acutely-
pointed termination.

This species of Petalodus is different in general characters to any other known from
the limestone strata of Great Britain. In breadth of the crown and small vertical
extent it somewhat resembles Petalodus rectus, Agass., but in the unequal develop-
ment of the two sides of the teeth and the number of imbricated folds separating
the crown from the base, it is quite distinct. It might be considered that this
peculiar form of tooth was due to its position as a side tooth in connexion with
other species of more regular form, were it not that it is confined to one locality in
the upper strata of the Limestone series of Yorkshire, whilst in the districts in
which the ordinary form of Petalodus is found P. inequilateralis is absent, so that it
is improbable that such can be the case.

In some respects this species appears to occupy an intermediate position between
Petalodus and Chomatodus; its thin sharp crown with serrated apex allies it to
Petalodus, whilst its great proportionate breadth and wide extent of surface
occupied by the coronal foldings resemble Chomatodus. The root is, however,
much more largely developed, more tumid and rounded than in Chomatodus.

Formation and locality ; Limestone, Wensleydale, Yorkshire.
Ez coll. Ear] of Enniskillen.

Genus.—Petalodopsis, Davis.

Teeth, medium size, strong. Crown, laterally strongly arched, smooth,
acuminate. Crest constitutes a sharp cutting edge, divided into three similar
denticles; centre one largest, with a deep sulcus on each side separating it from the
two lateral ones. Crown separated from root by a coronal band consisting of four
or five imbricating folds of ganoine, straight in the middle, bending downwards on
each side. Root descends from crown, as in Petalodonts; strong, fapering down-
wards, inbevelled; not so wide or deep as crown.

The affinities . this genus appear to be with the Petalodonts ; the sharp cutting
edge ot the tooth, and the well developed base or root, are clearly related to that
group. It appears to hold an intermediate position between Petalodus and Petalo-
rhynchus ; 1t is separated from the former by its tricuspidate crown, and from the
latter by the smallness of the root, absence of palate and paucity of denticles.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 499

Petalodopsis tripartitis, Davis.
(Pl, LX. tge. 6, 6a.)

The genus is represented by this single species, whose characters are those already
attributed to the genus. The tooth is ‘5 of an inch across, and about the same in
height. The crown is ‘35 of an inch high in the centre ; the central cone, or denticle,
is considerably more prominent than the lateral ones, which gives to the tooth an
acuminate form. The cutting edge of the outer denticles is slightly serrated, and
a number of minute striations descend from the crest vertically over the crown, but
disappear, and give place to a smooth, very finely punctate, enamelled surface.

Formation and locality : Carboniferous Limestone, Wensleydale.
Ex coll. William Horne, Esq.

Genus.— Polyrhizodus, M‘Coy.

Teeth, streng, transversely elongated. Crown, convex, obliquely elevated, more
or less oval in outline, and laterally acuminate ; posterior surface of crown, con-
cave, larger than anterior. Crown separated from base by anterior and posterior
ridges, with or without imbricating folds; base or root large, deeply implanted,
oblong, divided into distinct more or less tuberous rootlets or radicles.

This genus is probably more nearly allied with the Petalodonts than with any
other group; and it was, no doubt, this external resemblance, combined with, per-
haps, imperfect specimens, that led Prof. Agassiz,in the year 1840 (“Poissons Fossiles,”
tome iii., p. 174), to ascribe these teeth to the genus Petalodus (P. radicans). Spe-
cimens were so named in the collection of Lord Enniskillen and others, but, like
many other genera and species, were left for description to a future supplement,
which, unfortunately, has not been written. In a revision of the fishes of the
paleeozoic rocks, Prof. M‘Coy (‘Annals Nat. History,” Second Series, Vol. ii., p. 125,
1848) published a description of the genus, for which he instituted the name Poly-
rhizodus. The description was considerably enlarged upon, and specimens of two
species were figured by Prof. M‘Coy in his “Systematic description of the British
Palzozoic Fossils in the Geological Museum of the University of Cambridge,”
page 641, pl. 3k, figs. 2,6, 7,and 8. The Petalodus radicans, Ag., is described under
the name Polyrhizodus magnus. The second species, P. pusilus, does not appear
to be a Polyrhizodus, but probably belongs to the genus Helodus. ‘The figures of
Heiodus turgidus, Ag., in the “ Poissons Fossiles” do not represent the root or base of
the tooth as being divided into fangs or lobes, though one of the figures indicates it
to some extent; but in the Enniskillen collection, amongst an extensive range of
the H. turgidus, examples may be selected which show the division of the root even
to a larger extent than the specimen figured. :

During the Geological Survey of Illinois a number of fish remains were discovered
in the Carboniferous Limestone Series at Burlington and Chester, and amongst
''500 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

many others are several species of the genus Polyrhizodus. They are described by
Messrs. Newberry and Worthen in the Second Volume of the “Geological Survey of
Illinois,” published in 1866. The genus Polyrhizodus is somewhat restricted by the
wuthors to teeth like the British species, P. elongatus, shortly to be described—that
is, to examples having a much longer lateral than vertical axis, with the crown of
the tooth transversely low, and the root divided into numerous short, robust
radicles. In addition, a second genus, Dactylodus, is originated, which includes
specimens having essentially the same characters as those ascribed to Polyrhizodus,
except that the tooth is relatively longer vertically than laterally, the crown oval,
and the rootlets fewer in number (generally four or six), longer, and more robust.
A careful study of the numerous specimens from the mountain limestone of
Armagh leads to the conviction that no arbitrary line of the kind indicated in
the separation of these teeth into two genera can be maintained. The species
described in the following pages appear to be based on good reliable grounds, and
are types of considerable numbers of specimens in each case. Some have the
elongated form of the Polyrhizodus type of Messrs. Newberry and Worthen, whilst
others pertain equally to that of Dactylodus. The occurrence of intermediate forms,
however, bridges over the two genera and unites them ; or, if such be not the case,
it will be necessary to create other genera for the accommodation of each separate
form. It is probable that Messrs. Newberry and Worthen may have foreseen this
generic identity ; for in the fourth volume of “Survey of L[llinois” (1870), after
describing a new species of Polyrhizodus (P. truncatus), they remark :—“A compa
rison with the species we have named P. inflecus and P. porosus (Vol. IL., pp. 48,
49, pl. ii., figs. 8 and 9), will show that they should be placed in one generic group
with that now under consideration. From those species it is distinguished by its
outline, lower and broader than in P. inflewus, less low and broad than in P. porosus,
and by a root more nearly obsolete than in either.” The Polyrhizodus inflecus here

referred to is described as Dactylodus inflexus, whilst the P. porosus is described as a
Polyrhizodus.

Polyrhizodus radicans, Agass.

(Pl, Xs figs. 7, 8:)

Petalodus radicans— L. Agassiz, 1840. “* Rech. sur les Poiss.. Foss.,” Vol: LIL, p. 174
and 384,
5 -: U. G. Giebel, 1843. ‘“ Fauna der Vorwelt,” Vol. L., pt. 3, p. 345.
5 ; H. G. Bronn, 1848. ‘Nomencl. Paleont.,” p. 949.
Polyrhizodus magnus—F. M‘Coy, 1848. “Ann. and Mag. Nat. Hist.,” 2nd Ser., Vol. II.,.
p. 126.
Petalodus radicans— 4H. G. Bronn, 1849. ‘Enumerator Paleont.,” p. 646.
és J. Morris, 1854, Cat. Brit, Foss.,” p: 337.
Polyrhizodus ,, 3 1854. sienns 59 p. 340.
», | (magnus) i 1854. ee as) 5 p. 340.
at F. J. Pictet, 1854. ‘Traité de Paléont.,” Vol. IL, p. 271.

2
(Petalodus radicans) ” 1854. 5 Ss % p. 271
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 501

-Polyrhizodus magnus—F. M‘Coy, 1855. ‘Brit. Paleeoz. Foss.,” p. 641, pl. 3k., figs. 6, 7, 8.
6 radicans—Morris and Roberts, 1862. ‘“ Quart. Journ. Geol. Soc,,” Vol. XVIII, p. 101.
; Enniskillen, _ 1869. ‘Cat. of Type Spec. Foss. Fishes,” p. 7.
- . Young & Armstrong, 1871. “Trans. Geol. Soc., of Glasgow,” Vol. III., Supt.,
p, 76.

Armstrong, Young, )
. iy Q ‘ vs
Anal Bobo. On. 2 f 1876. “Catal. West. Scot. Foss.,” p. 63.

99 . J.J. Bigsby, 1878. “Thesaurus Devon.-Carb.,” p. 363.
5 (magnus) . 1878. a os . p- 363.

Teeth, when full grown 2°5 in. in breadth and 1°5 in. in height. The crewn ante-
riorly occupies one-third of the vertical diameter. From the anterior ridge it inclines
at an angle of 45° backwards and upwards to the crest formed with the posterior sur-
face. The anterior coronal surface is smooth, slightly polished, and convex ; it is
‘75 of an inch across the centre, from which the crest and anterior ridge converge
towards each lateral extremity, and terminate in an acute angle. From the raised
surface forming the centre of the tooth it is depressed laterally, and towards each
end is considerably bent downwards and backwards, so as to combine to form the
posterior median ridge. The anterior ridge dividing the crown from the root is
plain, and without folds or strize ; beneath the ridge the surface of the tooth retreats
almost at a right angle to the crown, with slight vertical plications towards the
base of the radicles. Posterior surface of the crown 1:0 inch across the central
portion ; vertically the section is concave; but laterally the surface forms a nearly-
straight line. It is ovoid in form, converging laterally to an acute angle. Lower
surface bounded by the posterior ridge *2 of an inch wide, and consisting of three
or four imbricating parallel folds. The ridge is considerably elevated, and a deep
groove extends beneath it and the base of the root.

Root, thicker than the upper part, its depth equalling one-third that of the
entire tooth. It is divided into twelve or fourteen thin plate-like radicles, deeply
cleft and usually separated by an indentation equal to their own diameter. There
are generally instances in each tooth in which two of the rootlets have coalesced
and form one thick, almost square fang.

Prof. M‘Coy has described and figured this species in his work on “ British
Palseozoic Fossils.” The specimens:at his disposal appear to have been smaller than
_ those now figured from the cabinet of the Earl of Enniskillen, but otherwise the types
agree. A slight discrepancy between M‘Coy’s description and the plate occurs.
In the text it is stated that the number of rootlets is six or eight, whilst in the
figure thirteen are represented. The latter is, no doubt, the correct number.

A considerable variety in the details may be observed in the large series of this
species collected from the Limestones of Armagh, and at present in the Enniskillen
collection. Full-grown teeth are generally more or less worn on the surface,
especially in the centre, considerable variety exists in the form of the teeth, in the
thickness and the relative size of the crown and the base. The specimens vary in
''502 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

size very much, and range from the large size of the specimen figured down to
about an inch in diameter, the latter, no doubt, being the teeth of younger fishes.

Nothing definite is known as to the arrangement of the teeth in the mouth.
Hitherto no specimens have been found which exhibited the relationship or relative
position of the teeth to each other. It is probable, however, judging from the
worn surface of the central portion of the tooth, that those of the lower and upper
jaws formed a corresponding cutting and triturating surface the one to the other,
but whether they existed in a simple double row extending backwards along the
palate and corresponding to the two rami. of each jaw, as might be inferred from
the sinuosity of the coronal surface of P. sinwosus, Davis. (vide page 504), or
they were arranged in concentric rows as in some of the large sharks at present
existing, there is no evidence to prove. In either case the strong, deeply-
implanted, many-barbed root indicates considerable power as well as voracity,
especially if compared with the somewhat weak and meagre attachment of the.
teeth in modern sharks. :

Locality : Comparatively abundant in the Carboniferous Limestone of Armagh.
Ex, coll. Earl of Enniskillen.

Polyrhizodus colei, Davis.

(Pl. LX., figs. 9, 10.)

Teeth, breadth across the crown 2 inches, height from tip of root to summit of
the crown 1°5 inch. Anterior surface of the crown large, convex, oval in form
with depressed lateral prolongations, extending considerably beyond the extension
of the root. The centre of the crown is ‘9 of an inch from the anterior ridge to its
summit. It is much worn, the portion of the surface most constantly used being
distinctly indicated by its appearance. The inclination of the surface of the crown
to the posterior ridge is about 60°. The surface is smooth and beautifully polished,
it possesses almost a transparent appearance, and the ramification of the nutrient
vessels is well defined. The lateral portions of the surface which are not worn —
any great extent do not exhibit this peculiarity, but are covered with minute punc-
tures. ‘he anterior ridge is doubly curved, upwards from each lateral extremity
and downwards to the middle portion of the crown ; it is smooth and partakes of
the general characters of the crown. The posterior surface of the crown is deeper
than the anterior: it is concave and bounded on its lower margin by a high ridge
which appears to have consisted of a single fold produced from the body of the
tooth. The root at its base is 1°5 inch across; towards its extremity it spreads
out to 1°6 inch. It is divided into six (or occasiooally seven) large club-shaped
rounded rootlets, which retreat from the posterior, and bend forward towards the
anterior face of the tooth. The radicles are sopanaie? by an interspace one-half
their own diameter between each.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 503

I take the liberty of appending the nomen triviale, Colez, to this beautiful species
in appreciative acknowledgement of the indebtedness of all students of Ichthyology
to the bearer of that name, the Earl of Enniskillen.

This species bears some resemblance to the tooth figured as Dactylodus princeps,
N. and W. (‘ Paleeon. of Illinois,” Vol. Il1., p. 45, pl. u11., fig. 6). The latter is deeper
and narrower, whilst the fangs are very long, on the anterior face the roots occupies
seven-tenths of the entire height of the tooth. 3

From all the British species P. colei is quite distinct and separate ; from P.
radicans it is distinguished by its greater height, broad crown, narrower space
occupied by the roots as compared with the breadth of the crown, and the fewer,
more robust, and rotund rootlets, The only other species to which it approaches is
P. sinuosus whose characteristics can scarcely be mistaken.

Locality : Carboniferous Limestone of Armagh,
Ex coll, Earl of Enniskillen.

Polyrhizodus elongatus, Davis.
(Pl. LX., figs. 16, 16a, 160.)

Teeth, length 2°75 inches, height 1:2 inch. The general outline of this species
is much broader in proportion to its height than P. radicans, but not so contracted
as P. attenuatus. The coronal surface is barely 5 of an inch in greatest breadth,
which is maintained along two-thirds of its length ; at each end it tapers rapidly to
a point, much depressed. The surface is slightly convex, covered with ganoine,
and where not worn, slightly punctate. The anterior median ridge is separated
from the crown by a considerable depression forming a long groove: the ridge is
composed of a strong single fold of ganoine, more deeply punctate than the crown,
and extending in a nearly straight line across the tooth, near the lateral extremities
it is bent downwards diagonally forming the end of the tooth and continued along
the posterior surface. The posterior surface of the crown occupies a much larger
area than the anterior, its greatest vertical depth is ‘9 of an inch. Its upper
boundary, with that of the anterior coronal surface, forms an acutely pointed crest.
The surface deeply concave and rough as though for the attachment of muscles.
The posterior median ridge prominent with three or four wavy, imbricating folds,
extending in an almost straight line across the spine ; it is separated from the root
by a deep groove. The root, separated from the anterior ridge by a sloping bony
surface equal in breadth to that of the crown, is divided into fourteen to sixteen
radicles or rootlets, circular, flattened, lobe-like; the flat sides lying parallel, separated
by half their own diameter. The radicles are ‘4 of an inch in length and the same
width from back to front, they occupy a more forward position with respect to the
crown of the tooth than any other species from the Armagh district.

- In-another example the anterior coronal surface from the median ridge backwards
is much depressed, and forms a concave instead of a convex surface, towards the

TRANS. ROY. DUB, SOC., N.S., VOL. I. 4H
''504 On the Fossil Fishes of the Carboniferous Inmestone Series of Great Britain.

back the surface rises and a sharp cutting edge is produced along the crest of the
tooth. The anterior median keel in this specimen is devoid of a ganoine fold and is
simply produced from the surface at a sharp angle.

The difference in the form of the crown of these specimens may be accounted for
if one of the teeth has been derived from the lower and the other from the upper
jaw, the convex surface of the one would fit almost perfectly to the concave surface
of the other.

This species bears some resemblance to Polyrhizodus littonr, N. and W. (“ Geolo-
gical Survey of Illinois,” Vol. II., p. 357; pl. iv., fig. 10). The American species is,
however, less than half the size of P. elongatus, the anterior band or ridge is
bow-shaped, with four closely approximated enamel folds, and there are only seven
or eight radicles, which have not the same characters as those of the Armagh
species.

Locality : Rare in the Carboniferous Limestone of Armagh,
He coll. Karl of Enniskillen.

Polyrhizodus sinuosus, Davis.
(Fl, 1om%., fige 1b, 12,12.)

Teeth, considerable difference in size; largest examples 1°7 inch across the
coronal surface, and 1:1 inch from crown to extremity of fangs; smallest size is
‘4 across and ‘34 in height ; between the two a variety of intermediate sizes may
be traced. Crown, flattened or slightly convex, compressed to a sharp edge along
the crest ; margins of the coronal surface unsymmetrical ; crest for the most part
straight, bent at each extremity—on the right at a sharp angle, and on the left at
a more obtuse one—to form the lateral outlines ; the anterior median ridge forms a
sigmoidal curve, one-half the crown being double the diameter of the other. The
greatest breadth is -5 of an inch near the centre of the tooth; to the right this is
reduced by the tenth of an inch, to *25 of an inch, and becomes still more restricted
towards its lateral extremity ; in the opposite direction the crown maintains its
greater breadth, ending laterally in an obtusely rounded margin. The ridge formed
by the anterior margin is minutely corrugated transversely to its axis; the corrus
gations extend a short distance over the surface of the crown. The posterior coronal
surface is not exhibited. A section of one of the teeth shows it to have been deep
and extended far towards the base of the root. The inter-basal space recedes consider-
ably from the anterior margin of the crown, forming a deep hollow preceding the
base of the rootlets. Its surface is smooth, or very slightly punctured, the lower
part corrugated contiguously with the insertion of the roots. The root is deeply
fissured, forming four large, prominent globose radicles of unequal size. They are
1°35 inch across, being one-fifth less than the breadth of the crown.

In the smaller specimens the radicles are longer and more attenuated in propor-
tion to the size of the tooth. The general form of the tooth, the peculiar sigmoidal
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain, 505

curve along the anterior median ridge, and straight crest of the coronal ,region
appear, however, to be sufficiently indicative that they all belong to the same species,
and that the difference in size represents only periods of growth,

A difference in form may be noted in this species which could not be easily
observed in a symmetrical one. The peculiar curve in the median ridge in some of
the teeth proceeds in the contrary direction to the one described above, and in place
of the more attenuated extremity of the coronal surface being towards the right of
the tooth, it is towards the left side. This difference leads to the inference that the
teeth were in pairs in the mouth.

Locality : Mountain Limestone of Armagh.
Ex coll. Karl of Enniskillen.

Polyrhizodus attenuatus, Davis.
(PICEX., fie, 12)

Teeth, extremely elongated in proportion to their height; length 1°8 of an
inch ; height ‘5 of an inch. Crown elliptical, narrow, slightly convex, compressed.
to a thin, acutely-pointed, slightly-serrated edge along the nearly-straight crest ;
laterally the coronal surface is depressed towards the acutely-pointed lateral angles.
The anterior margin forms a prominent ridge at a right angle to the ‘basal area,
almost straight in the median region, slightly rounded towards the base at each
end ; a single enamelled fold extends along its entire length ; posterior face of the
crown considerably deeper than anterior, slightly concave in each direction ; slight
striations extend from the minutely denticulated crest down the surface ; lateral
extremities obtusely rounded, with a slightly-raised border ; basal border broad,
with seven or eight delicately imbricating folds, moderately elevated above the
coyonal surface—more so above the basal area, from which it 1s separated by a
eroove. The anterior basal area occupies a space about equ al to that of the crown.
It is concave, and gently rounded towards the roots ; upper surface distinctly: pus-
tulate, the spots placed indiscriminately, without arrangement ; near the base of
the rootlets, a peculiar series of duct-like striations terminating in a prominent
pustule attached to each at its upper termination. | Downwards the striz
descend to, and are absorbed in the general mass of the roots. The root
divided into a variabie number of radicles. The largest number is, perhaps, on the
specimen figured, there being twenty-two. The radicles circular in section are
irregular in size, and vary on the same specimen from ‘2 to ‘1 of an inch in length,
the shorter ones generally being thin and small. The coronal surfaces are enve-
loped in a coating of ganoine, preserved on their lateral expansions, but general
worn off in the centre by the attrition of the grinding and cutting surfaces of the
teeth. Where the surface beneath the enamel is exposed by its removal it is seen,
when magnified, to be full of nutrient ducts, which ramify along the surface, with

many devious sinuosities.
4u2
''506 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

It was remarked, when describing P. elongatus, that one portion of the teeth
have an anterior coronal surface which is convex, whilst another is concave along
the same area. Some of the teeth belonging to the genus now being described
exhibit the same peculiarity. Their general resemblance in other respects almost
precludes the possibility of their being different species. They have about the
same number of radicles to the roots; the posterior aspect of the tooth is the same
in both, and the peculiar development of the duct-like marking on the anterior
basal region is exactly the same in each. The anterior portion of the crown, how-
ever, offers several peculiarities differing in the two. The anterior coronal surface
is concave, and more compressed along the crest, producing a very sharp cutting
edge, slightly crenulated. The anterior median ridge is more prominent, and con-
stitutes an acute angle with the upper basal area; and it is devoid of the band of
enamel which stretches across the teeth already described. It appears probable
that these were teeth from the upper jaw ; whilst those with a convex crown have
been derived from a lower jaw. As to whether there were several of the teeth form-
ing concentric rows, as in the sharks, or whether they were arranged otherwise,
there is no evidence, except the general character of the teeth, to show.

This species possesses characters which separate it from all others hitherto
described. Its long, pectinated appearance and the number of its radicles, easily
distinguish it. The one nearest resembling it is P. piasensis, St. J. & W. (“ Geol.
Surv. Illinois,” Vol. VI., p. 386, pl. 13, fig. 12), it is little more than half the size,
and possesses only nine or ten radicles.

Formation and locality : Mountain Limestone, Armagh.
Ez coll. Earl of Enniskillen.

Polyrhizodus constrictus, Davis.
(Pl ix, fe. 15.) :

Teeth, crown very small in comparison to the base or root. Greatest diameter
of crown 1:1 inch; diameter of root along the same plane, 1°65 inch; depth of
tooth from the surface of crown to bottom of roots, ‘75 of aninch, The crown is
narrow from back to front, not more than ‘3 of an inch, smooth, and its central por-
tion, much worn by trituration, rises at a slight angle from the anterior ridge to the
crest ; lateral extremities much raised ; surface falling from each end towards the
centre, and forming a deep concavity ; anterior ridge continuous with the crown of
the tooth without demarcation, but stands boldly forward above the narrow inter-
basal area ; ornamented by four or five imbricating folds of the ganoine, by which
it is covered ; posterior surface partially imbedded in the matrix. It extends from
the slightly rotund coronal crest to form a junction with the rootlets, and is not
marked by any very distinct posterior ridge. The roots are large, tuberculous,
broader than the crown of the teeth from back to front; the largest in centre ‘45
of an inch in diameter. The rootlets towards each end of the tooth are smaller;
''On the Fossil Fishes of the Carboniferous Limestone Serves of Great Britain. 597

there are eight radicles preserved, two pairs being anchylosed. The spaces between
the radicles are narrow in front, but expand to a greater width behind. The sur-
face of the rootlets or radicles is indiscriminately pustulated or reticulated. Where
fractured they show a close and fibrous texture.

This tooth is altogether dissimilar to any other species. It appears to be consi-
derably worn by attrition along the surface of the crown; but it is not probable
that its deep circular lateral concavity has been formed by the surface being worn

away in this manner. .
Formation and locality : Carboniferous Limestone of Armagh.
Kx coll. Earl of Enniskillen.

Genus.—Chomatodus, Agassiz.

“Teeth, transversely much elongated, compressed and depressed. Crown having
the homologous parts of Petalodus, and the form and structure of Polyrhizodus—
root short, sometimes obsolete, undivided.”—( Worthen. )

In 1848 Prof. M‘Coy added two new species to the genus Chomatodus, described
in the Annals and Mag. of Nat. Hist., Vol. ITL., p. 115, as C. obliquus and C. den-
ticulatus. Six years later his work on the British Paleeozoic Fossils was published,
in which (p. 617) after describing the general characters of Chomatodus, he writes,
“This genus has, I think, no claims to be retained ; the blunt-coned, thick species
(as C. cinctus, &c.) might be advantageously classed with Helodus, most of the species
of which, with the same form and punctured surface, have more or less perfectly
developed imbricating folds at the base of the crown; and the thin unpunctured
species with a cutting edge belong to Petalodus (Owen), in which the folds always
exist. I use the genus here for some intermediate types provisionally, and for
Agassiz’s species.” ,

Prof. M‘Coy very accurately attributed little importance to the occurrence of a
greater or smaller number of concentric folds around the base of the teeth, from
which Agassiz instituted the genus Chomatodus. Such folds are present on a con-
siderable number of genera, and in no way serve to distinguish them from each
other. Of the three species of Chomatodus described and figured by Prof. Agassiz,
the third C. acuminatus (Pois. foss., Vol. III., p. 108, Tab. 19, figs. 11, 12, and 18),
is without doubt a species of Petalodus. It is an unique specimen discovered by
Sir R. Murchison, in the limestone at Whorlton in Durham. Agassiz observes
(op. cit., p. 159) that this species must be eliminated from the genus Chomatodus,
because of its trenchant cutting edge, and placed with the Hybodonts, or more pro-
perly with the sharks (Squalides) properly so called. It will be included in the
new genus Petalodus of Owen.

The second species C. cinctus, Agass., appears to be entirely see of teeth
which are indistinguishable from Helodus or Lophodus, and are now included i in
one or other of those genera.
''598 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

The third species, Chomatodus linearis, Ag., possesses characters which separate
some of the figured types clearly from both the genera Helodus and Petalodus,
though there is evidently more than one genus represented. It is probable that
the small somewhat circular and thin tooth (op. cit., Pl. 12, fig. 5) is a Petalodont,
allied to the genus Antliodus, N. and W., whilst some of the figures have more than
a passing resemblance to Ctenoptychius. The majority of the figures represent
examples having an elongated, more or less straight, cutting edge ; surrounded or
not by concentric folds or plicee ; a somewhat expanded anterior and posterior
coronal margin, and a short bi-concave root. ‘These teeth pertain, in all essential
respects, to a Petalodont type, very similar in form to the most elongated species
of Polyrhizodus, except that the root or base is simple and undivided. Figs, 8,
9, 10, 12, and 13, loc. cit. seem to represent teeth possessing these characters, and
may be taken as the types of the genus as now restricted.

Mr. Worthen, whilst describing a number of fossil fish remains found in Illinois,
has adopted the same arrangement. The genus Chomatodus is retained by this
accomplished ichthyologist, and the C. linearis, Agass., is taken as the type of the
genus ; ten new species are then added from the sub-carboniferous limestone. The
genus, as defined by Mr. Worthen, comprehends “teeth transversely much elon-
gated, compressed and depressed, crown having the homologous parts of Petalodus

and the form and structure of Polyrhizodus—root short, sometimes obsolete,
undivided.”

Chomatodus linearis, Agass.

(Pl. LXL, figs. 1, 1a.)

Psammodus linearis—L. Agassiz, 1833. “Rech.surles Poiss. Foss.,” Vol. IIL, pl. xii, figs. 5-13.
» 3 P. de G. Egerton, 1837. “Catalogue of Foss. Fishes.”
Chomatodus _,, L. Agassiz, 1840. “Rech. s. 1. Poiss. Foss.,” Vol. IIL, p. 108, pl. Xii.
figs. 5-13.
re Pp J. E. Portlock, 1843. ‘Geol. of Londonderry, &c.,” p. 446, pl. xiv., fig. 8.
: 4 C. G. Giebel, 1843. ‘Fauna der Vorwelt,” Vol. I., pt. 3, p. 341.
» ” H. G. Bronn, 1848. “ Nomencl. Paleont.,” p. 293.
9 o - 1849. “ Enumerator Paleont.,” p. 647.
is be J. Morris, 1854. “Cat. Brit. Foss.,” p. 321.
ma > F. J. Pictet, 1854. ‘ Traité de Paléont.,” Vol. II., p. 266.
», (Helodus) ,, F. M‘Coy, 1855. ‘ Brit. Paleoz. Foss.,” p. 618.
si as Morrisand Roberts, 1862. ‘Quar. Jour. Geol. Soc.,” Vol. XVIII, p. 100.
- a Young & Armstrong, 1871. “Trans. Geol. Soc., Glasgow,” Vol. IIL, Supt., p. 69.
a 2? at eee oe \ 1876. ‘Catalogue West. Scot. Foss.,” p. 60.
: F J. J. Bigsby, 1878. “Thesaurus Devon.-Carb.,” p. 349.
9 ” L. G. de Koninck, 1878. ‘Fauna du Calc. Carb. de la Belgique,” p. 47, pl. vi.,

fig. 5.

Teeth, medium size, average ahout three times as long as broad, median ridge
depressed, straight or slightly curved; length 1:0 to 1:25 inch, breadth ‘3 of an
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 509

inch, height of crown ‘15 to 2 inch. Crown: median ridge extends along central
longitudinal axis, straight, uniform, without serrations or cones—anterior surface,
slight convexity from apex to base; laterally straight or convex ; posterior surface
parallel with the anterior one, concave in both directions ; anterior and posterior
ridges somewhat expanded, margins occasionally serrated. Lateral borders oblique
and angular.. Coronal surface enamelled, apex deeply and coarsely punctate. A
number of concentric imbricating folds or plicee encircle the base of the crown,
parallel with its margin. Base not well exposed, appears to be short, and deeply
and doubly concave. |
An example in the Enniskillen collection, from the Mountain Limestone of
Richmond, in Yorkshire, differs in some respects from the Armagh type. The
tooth is broader in the central portion in proportion to its length, laterally it
becomes attenuated, and ends in a more or less acute point. ‘The surface is
punctate, and wide and irregularly sinuous folds extend along the anterior surface,
most strongly marked near the apex, whilst near the base they are almost imper-
ceptible. On the posterior surface the plice or folds are arranged concentrically ;
they are smaller and more numerous. Though this specimen differs in several
respects from the type, and it is not improbable that it may belong to a separate
species, yet it will perhaps be advisable to retain it with Chomatodus linearis, Ag.,
until more extended observation shall have demonstrated its real characteristics. ~

Formation and Locality : Mountain Limestone. Armagh, Bristol, Richmond in Yorkshire.
He coll. Karl of Enniskillen.

Chomatodus acutus, Davis.
(Pl. LXL., fig. 2, 2a.)
Chomatodus linearis, Ag., “‘ Poiss. Foss.,” p. 108, Tab. XIL, fig. 5-13.

Tooth, not perfect, broken at one end, length preserved ‘7 inch, depth anteriorly
‘3 inch, posteriorly ‘2 inch, width equal to the posterior height. Crown, trans-
versely acuminate ; apex, thin razor-shaped, with sharp cutting edge, straight ;
anterior and posterior surfaces concave with slight vertical corrugations, slightly
expanded to form the ridges:separating the crown from the base ; base not exposed.

This species differs from C. linearis, Ag., in the acutely pointed knife-like apex of
the crown, and in the constricted character of the anterior and posterior margins.

Formation and locality : Carboniferous Limestone, Armagh.
Ex coll. Karl of Enniskillen.

Genus.—Glossodus, M‘Coy.
Glossodus.—F. M‘Coy, 1848, Ann. and Mag. Nat. Hist., 2nd Ser., Vol. IL, p. 127.
Teeth, tongue-shaped, oblong, quadrangular, much higher than wide ;
-crown elevated, slightly recurved, narrowing from the base to a small, sub-
truncate apex; surface porous, puncta generally seeming confluent towards the
''510 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

apex ; punctured surface terminating below ina notch, or arched line, the convexity
upwards ; root long, as wide as crown, coarsely fibrous.—(M‘Coy, Ann. Nat. Hist.,
Second Series, Vol. II., p. 127.) .
A number of teeth of considerable diversity of form appear to be included in the
above generic description. It is difficult, however, to distinguish amongst them
specimens which exactly supply the characters ascribed by Prof. M‘Coy to Glossodus
lingua-bovis described in the volume of the Magazine of Natural History referred
to, but not figured. The majority of the specimens belong to the species
G. marginatus, M‘Coy, also described in the Mag. of Nat. History, and afterwards
figured in Brit. Paleeoz. Foss., p. 629 Pl. 3 k., fig. 1. The latter, it is stated,
may be easily distinguished from G. lingua-bovis by its more finely punctured, glossy
surface, rounded tip and prominent lateral margins. These characters are
possessed to a large extent by all the specimens, and those applied in the
discrimination of G. lingua-bovis, viz., of possessing a dull surface, the antero-posterior
diameter being only equal to half the width of the base, and the latter three times
the width of the truncated apex, do not appear to be characteristic of any of the
specimens. It is probable that all may belong to the same species, and as
G. marginatus has been figured and redescribed by Prof. M‘Coy, whilst C. lingua-
bovis was not transferred forward to the Brit. Paleeoz. Fossils, it will be preferable
to retain the former specific name—though, as will be presently explained, the
species will include a much wider variety than was contemplated by Prof. M‘Coy.

Glossodus marginatus, M‘Coy.
(Fl Xd, ties. 2, ga, db, 4, 5, 5a.)

Glossodus marginatus—F. M‘Coy, 1848, “Ann. & Mag. Nat. Hist.,” Ser. 2, Vol. I. p. 128,
»  lingua-bovis, if 1848. ‘ 49 bi Sere2,/Vol. L1., p, 124,
§ i. F, J. Pictet, 1854, “ Traité de Paléont.,” Vol. II., p. 259.

» marginatus, . 1854. - a Vol. tik; p, 259;
a ye 8. Mlones, 1854. “Catal. Brit. Koss.,” p. 327.
»,  lingua-bovis, G 1854. os 5 p. 327.
» marginatus—F. M‘Coy, 1855. “' Brit. Paleoz. Foss.,” p. 629, pl. 3 K., fig. 1.
si 4 Morris and Roberts, 1862. ‘“ Quart. Journ. Geol. Soc.,” Vol. XVITL, p. 100.
»,  lingua-boyis, - is 1862. 3 ‘5 Vol. XY LEL,-p,, 100,
» Mmarginatus—Young and 1871, “Trans. Geol. Soc., Glasgow,” Vol. III., Supt.,
Armstrong, ps1.
Deg a 1876. “Catal. of W. Scot. Fossils,” p. 61.
and Robertson,
»,  lingua-bovis—J. J. Bigsby, 1878. ‘Thesaurus Devonico-Carb.,” p. 355.
» marginatus, 4 1878. i. is 5 op. BDO,

Teeth, varying from 1 inch to ‘2 inch in length; average example ‘7 inch in length,
‘25 inch across the base of the crown, and converging to an apex more or less shaped
like a tongue, or in some instances much more acuminate—diameter from back to
front equal or greater than the width of the base. The crown is elevated and
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 511

recurved backwards; anterior surface, occasionally much worn by attrition of an
opposing tooth, is convex transversely, its lateral edges meeting those of the pos-
teriqr surface, and forming more or less prominent lateral margins. The basal
portion of the anterior surface is produced on each side of the median line to form a
sub-angular prominence, from which the base proper retreats very rapidly, with a
concave flexure, towards the posterior surface of the tooth. Posterior surface, more
or less recurved near the apical extremity, concave, and laterally expanded ; separ-
ated from the base by a sigmoidal curve. The whole coronal surface is enamelled
and covered with punctures, the latter in some instances near the apex, being con-
verted into anastomosing canals by the wearing of the surface. Base nearly as long
as the crown, coarsely fibrous, extending vertically from the posterior coronal face,
and with a deep concavity posteriorly.

A unique specimen occurs in the collection of the Earl of Enniskillen which exhibits
a series of teeth in situ, showing, at any-rate in part, the arrangement of the teeth
in the mouth (see Plate LXI., fiz. 4). The specimen consists of three or four teeth,
arranged one behind the other, in a very similar manner to those of Petalorhynchus
or Janassa. The most anterior tooth is the smallest, and the series increases in size
backwards, the tooth in use being the largest and most recent. By a peculiar arrange-
ment the anterior sub-angular prominences, from the basal portion of the crown
already mentioned, fit and are attached to corresponding depressions in the concave
posterior surface of the preceding tooth. It is probable that five teeth occurred
in each vertical series, and it is a natural inference that several of these vertical
rows were extended side by side laterally.

There are examples of teeth which differ in details of form from the types de-
scribed above. In some instances the apex is pointed, and the posterior basal
part of the crown expanded so as to extend beneath the cone of the succeeding
tooth (Plate LXI., tig. 5). These do not appear to be such differences as to render
necessary the formation of a separate species, but may very well have been the
teeth of either the opposite jaw or from a different part of the same jaw.

Formation and locality : Mountain Limestone, Armagh.
Kz coll, Kav of Enniskillen.

Genus.—Ctenopetalus, Agass., MSS.

Teeth of small or medium size; crown broad, compressed, gently rounded in
outline ; cutting edge divided into from twenty to thirty small denticles; base
of crown possessing three or four imbricating folds of ganoine, descending lower
on posterior than anterior surface; root narrower than crown, flattened, and
about equal to it in height.

The genus Ctenopetalus along with that of Harpacodus originally constituted a
part of the genus Ctenoptychius of Agassiz; they were named _ respectively
Ctenoptychius (Ctenopetalus) serratus, Ag., and C. (Harpacodus) dentatus, Ag.
They were both obtained from the Mountain Timestone; the other species of

TRANS, ROY. DUB. SOC., N.S., VOL. I. a0
''512 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

Ctenoptychius, which are still included in the genus, are from the Coal Measures ;
so far as at present known the genus Ctenoptychius is not represented during the
Carboniferous Limestone period. In 1859. Prof. Agassiz revised the group and
made the above-named species form the types of new genera. These genera have
not hitherto been described, but the types have remained in the collection at
Florence Court. Professor Agassiz, in the “ Poissons Fossiles,” considered that the
Ctenoptychians present a great resemblance to an Orodont squeezed flat. Their
general form, however, is without doubt nearly related to the Petalodonts. The
convex surface of the anterior face of the crown and the concave surface behind,
form a very near resemblance to the petal-shaped tooth of Petalodus ; they are
distinguished by the deeply denticulated or pectinated cutting surface. “ Whilst
agreeing in the possession of a family likeness one with the other, they exhibit con-
siderable generic distinctions. The genus Harpacodus differs from the other two in
its thick, strong crown, and the almost straight contour formed by the enamelled
tips of its denticles. The constricted, tumid, and prominent bony base is quite
different from the flattened bases of Ctenopetalus and Ctenoptychius. The denti-
culation of the three genera is sufficiently distinct. Ctenoptychius, though pos-
sessing about an equal number of denticles with Harpacodus, is distinguished by
their peculiar irregularly accuminate arrangement, whilst in Harpacodus they
extend almost in a straight line across the tooth. The denticulation of Ctenopetalus
is easily discriminated by the large number of denticles and their comparative
smallness in proportion to the size of the tooth.”

Ctenopetalus serratus, Agass. MSS.

(Pi 1 sigs. 6,)60; 27; 33)

Ctenoptychius serratus—L. Agassiz, 1833. “Rech. s. lL Poiss. Foss,” Vol. IIT., pp. 173, 383.
Petalodus . R. Owen, 1840. “ Odontograpiy,” p. 62.
Ctenoptychius _,, J. E. Portlock, 1843. “Geol. Rept. on Londonderry,” &c., p. 461.
An As C. G. Giebel, 1848. “Fauna der Vorwelt,” Vol. L, pt. 3, p. 345.
S A H. G. Bronn, 1848. “Nomencl. Palont.,” p. 356.
A ms es 1849. ‘ Enumerator Paleont.,” p. 646.
5 5 J. Morris, 1854. “Cat: Brit. Foss.,” p. 324.
5 He). Pictet, 1854.  “Traité de Paléont.,” Vol. IT., p. 264.
3 s FEF. M‘Coy, 1855. “Brit. Paleoz. Foss.,” p. 626, pl. 3 L, figs. 21, 22, 23.
o pectinatus—E. W. Binney, 1855. ‘Trans. Manchester Geol. Soc.,” Vol. I, pl. v.,
figs. 20, 21.
Ctenopetalus serratus—L. Agassiz, 1859 “Enniskillen Coll. MSS.”
a o Morris & Roberts, 1862. “ Quart. Journ. Geol. Soc.,” Vol. XVIIL, p. 101.
5 : Enniskillen, 1869. “Cat. Type Specimens,” p. 4.
Ctenoptychius _,, Young & Armstrong, 1871. ‘Trans. Geol. Soc. Glasgow,” Vol. ITI.,Supt., p. 71.
Ctenopetalus » (mT enetae t 1876. “Catal. W. Scot. Foss.” p. 61.
A J. J. Bigsby, 1878. “ Thes. Devon.-Carb.,” p. 353.
Ctenoptychius._,, . 5 ‘9 p. 353.

Ctenopetalus “5 J. W. Davis, 1881. “Ann. and Mag, Nat. Hist.,” p. 626.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 513

Teeth ; “Wide, much compressed, upper cutting edge having a gentle but
variable convexity ; usually divided into about thirty rounded notches, or obtuse
pointed denticles, slightly larger in the middle than at the ends, and from between
each pair of which a more or less distinct sulcus extends towards the base of the crown,
rarely reaching more than halfway, and fcrming a fringe-like plication, and some-
times nearly obsclete; apices of the denticles minutely crenulated under the lens ;
front surface of crown flat, highly polished, sloping outwards, and terminating in an
obtuse angle in the middle, and directed downwards and outwards; the very
prominent base of the crown being surrounded by three or four flat imbricating
bands of ganoine; root abruptly flattened, also narrower than the crown, and
about equalling it in depth.”—M‘Coy. The posterior surface of the crown is deeply
concave, smooth in the central part, plications at base of crown prominent, extending
with considerable convexity towards the base and much lower than on the anterior
surface. Coronal margin minutely serrated corresponding with the minor crenula-
tions of the anterior surface, but the larger obtusely denticulated groups are not
represented on the posterior face. Breadth of crown about °8 of an inch; height of
crown anteriorly ‘3 inch; root one-third longer than the crown ; posteriorly the
crown is higher than the depth of the root.

Formation and locality : Mountain Limestone, Armagh.
Hz coll. The Earl of Enniskillen.

Ctenopetalus crenatus, Davis.
(Plc XT, fies. 9, 90, (80a)

Teeth, small, +4 of an inch across the crown, and ‘25 inch in height. Crown,
anteriorly slightly convex between the lateral extremities ; cutting edge slightly
rounded, and divided into a number of minute denticles, smooth, obtusely-rounded,
without minor division, which distinguishes them from C. serratus. Enamelled
surface of the crown bounded below by several plicated folds of ganoine, the upper
one enveloping the base of the crown. Lateral extremities of the front face acum-
inate, expanding towards the centre, which descends over the root with a promi-
nently-advanced acute point. Posterior surface of crown concave, descending to
nearly twice the depth of the anterior one, towards the root. Five or six broadly
expanded plications occupy the base; root narrow, thin, anteriorly much con-
tracted.

This beautiful little species possesses all the generic characters of Ctenopetalus,
but is different in several respects from the type species C. serratus of Agassiz. Itis
less robust ; the median portion of the anterior face of the crown forms an acute point,
which in C. serratus is rounded-and obtuse, and the apices of the denticles are smooth
and undivided. This species bears a considerable resemblance to Q. medius, from
the Chester Limestone, Illinois (“ Palzont. Illinois,” Vol, VI., p. 400), but is dis-
tinguished by the pointed apex of the crown in the latter, by each denticle having

452
''514 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

a short, sharp, crested carina, and by its possession of a single fold of enamel only
along the base of the crown.

Formation and locality : Carboniferous Limestone, Wensleydale.
Ex coll. Wm. Horne, Esq., Leyburne.

Genus.—Harpacodus, Agass. MSS.
Ref.: “Annals and Magazine of Nat. Hist.,” Dec. 1881, p. 424.
Teeth small ; crown slightly convex, strong ; cutting edge very slightly circular,
divided into 5-8 deeply-cut, broad and strong denticulations; base of crown promi-
nent, with a single broad fold of ganoine, deeper posteriorly than in front ; root at

its junction with the crown much constricted ; lower it is expanded, large and
tumid.

Harpacodus dentatus, Agass. MSS.
(PY Gx fie. 20.)

Ctenoptychius dentatus—L. Agassiz, 1833. “Rech. s. ]. Poiss. Foss.,” Vol. III, pp. 173
and 383.
2 macrodus, a 1833. “Rech. s. 1. Poiss. Foss.,” Vol. IIL, pp. 173
and 383.
Petalodus dentatus— R. Owen, 1840. “ Odontography,” p. 62.
Ctenoptychius macrodus—J. E. Portlock, 1843. “ Geol. Rept. on Londonderry,” p. 467, pl. xiv.,
fie.1.
Petalodus dentatus, io 1843. “Geol. Rept. on Londonderry,” p. 467.
Ctenoptychius C. G. Giebel, 1848. “ Fauna der Vorwelt,” Vol. L., pt. 3, p. 345.
., macrodus oe ” » ” ” ” ”
i 93 H. G. Bronn, 1848. “ Nomencl. Paleont.,” p. 356.
x dentatus Be a a5 a -
8 S Ma 1849. ‘ Enumerator Palont.,” p. 646.
se macrodus ss 2 5 z a4
Bs s J. Morris, 1854. ‘Catal. Brit. Foss.,” p. 324.
4 dentatus 5 ee a a 3
s 5 F. J. Pictet, 1854, “ Traité de Paléont.,” Vol. IL., p. 264.
= macrodus a s eS 5 a an
Harpacodus dentatus—  L. Agassiz, 1859. “ Enniskillen Coll. MSS.”
. is Morris and Roberts, 1862. ‘ Quar. Journ. Geol. Soc.,” Vol. XVIITL., p. 100.
v = Enniskillen, 1869. “Catal. Type Spec.,” p. 5.
Ctenoptychius _,, ‘Young & Armstrong, 1871. “Trans. Geol. Soc, Glasgow,” Vol. LIL,
Supt., p. 71.
S (Harpacodus) “p { ‘ah NenaneS j 1876. “ Cat. W. Scot. Foss.,” p. 61.
i :; és J. J. Bigsby, 1878. “ Thes. Devon.-Carb.,” p. 353.
Harpacodus __se», oe Dawg. 1881. “‘ Ann. and Mag. Nat. Hist.,” p. 426.

Teeth small, strong, ‘4 inch in lateral diameter, °4 inch in height; height
divided equally between the base and the crown. Crown oval in outline, laterally
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 515

convex, lower part thick and strong; crest slightly arched or straight, divided
into about seven denticulations, large, broad at the base, laterally thin, and
obtusely pointed ; lateral denticles slightly smaller than those of the centre. The
denticles divide the crown to one-half its depth, and between each the line of divi-
sion is continued, forming a sulcus extending almost to the base of the crown. The
latter is prominent, and forms a single broad fold or ridge extending across the
anterior coronal surface, and on each side bending downwards, and thence envelop-
ing the posterior surface of the crown. Posterior surface is concave laterally, and
extends one-third lower from the apex than the anterior surface. Surface of crown
is thickly enveloped with ganoine of a particularly hard and dense character, espe-
cially near the apex or crest. Base proportionately thick and strong, narrower
than crown; anterior surface contiguous to crown much depressed for about one-
third its vertical extent; below this the base is tumid, prominent, rounded and
thick, fibrous, and close in structure.

Formation and locality : Mountain Limestone, Armagh.
Ex. coll. Earl of Enniskillen.

Harpacodus clavatus, Davis.
(Pl, UXL, fig. 20.)

Teeth, small and delicate, ‘1 inch in height, and ‘25 inch. broad. Crown,
circular, base and apex, sub-parallel. Cutting edge divided into eight minute
rounded, clavate, obtusely pointed denticles, coated with glistening enamel,
diminishing with an extremely slight gradation in size towards each lateral
extremity. The denticles occupy more than one-half the surface of the crown.
Base of crown is imperfect, but was somewhat prominent, and apparently a fold of
the ganoine separated it from the root. Posterior surface not visible. Root very
short, conforming to the generally circular form of the crown—thick from back to
front, and somewhat produced downwards at each end.

This species differs from Harpacodus dentatus, Ag., in its broad circular form and
short low crown. The denticles are greater in number, well-defined, with a clavate,
rounded extremity, those of H.dentatus being broader at the base, thin, with a laterally
obtuse point. The base of this species is also quite distinct from that of H. dentatus,
for whilst the latter is boldly prominent with a well-rounded tumid root, /. clavatus
has a very short root, thick and widely expanded, and whilst it possesses the
appearance of being perfect, it differs so much from the type specimen in this
respect that it may be possible that a part of the root has been broken away.

Formation and locality : Mountain Limestone, Armagh. Unique specimen.
Ex coll. Earl of Enniskillen.
''516 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

Genus.—Petalorhynchus, Agass., MSS.

Teeth, medium size, arranged in’ five or six horizontal rows of at least
three teeth each, probably five or seven. Central primary teeth beak-shaped,
lateral ones less pointed. Apex of crown constitutes a sharp cutting surface.
Crown, anteriorly convex, with a median ridge extending from the point downwards
to the base ; posteriorly it is concave and spatulate ; a series of four or five sigmoidal
imbricating plicee extend along both surfaces of the tooth, dividing the crown from
the base ; posterior coronal surface larger than anterior. Base, tapering, osseous,
very long and undivided.

(Teeth, small; crown compressed, thin, concavo-convex petal-shaped, relatively
higher and narrower than in Petalodus ; imbricating folds on posterior face forming
a short, transverse band, not extending to the lateral angles of the crown ; root long,
undivided.’—Newberry and Worthen.)

Petalorhynchus psittacinus, Agass., MSS.

: (PL XT, fies 12, 13, 14, 15, 16, 16a, 16D.)

Chomatodus | accuminatus!—L. Agassiz, 1833.  “‘ Rech. sur les Poiss. Foss.,” Vol. I1f., p. 108.
(partim).
Petalcdus psittacinus— L. Agassiz, 1840. ‘Rech. sur les Poiss. Foss.,” Vol. ITT., pp.174.
and 584.
5 sagittatus, - 1840. ‘Rech. sur les Poiss. Foss.,” Vol. III., pp.174
and 384.
os 5 J. E. Portlock, 1843. ‘Geol. Report on Londonderry, ” p. 461.
fe psittacinus, Fh 1843. 5 es op p-. 461.
i a C.. G. Giebel;. 1848. ‘Fauna der Vorwelt,” Vol. L., pt. 3, p. 345.
4; sagittatus, # ; 1848. s . o, Vol. I. pt. 3, p. 345.
i S5 H. G. Bronn; 1848. ‘Nomencl. Paleont.,” p. 949.
a psittacinus, - 1848. . - p. 949.
% ss iS 1849. ‘Enumerator Paleont.,” p. 646.
5 sagittatus, s, 1849. 45 % p- 646.
9 s J. Morris, 1854;. “ Cat. Brit. Foss.,” p. 337.
ms psittacinus, - 1854. . 3 sj Paes
ae 3 F..J. Pictet, 1854. “Traité de Paléont.,” Vol. II., p. 272.
. sagittatus, 5 1854. ener ; Vol IL, p. 272.
5 psittacinus, F. M‘Coy, 1855. ‘Brit. -Paleoz. Foss.,” p. 636, pl. 31, fig. &
es sagittatus, 33 1855. . x » p- 636, pl. 3i, figs. 2, 3.
Petalorhynchus psittacinus—L. Agassiz, 1859. “Enniskillen Coll., MSS.”
o 0 Morris and Roberts, 1862. ‘Quart. Journ. Geol. Soc.,” Vol. XVIII,
peldl

Petalodus sagittatus— 3 1862. “Quart. Jourm Geol. Soc.” Vol. XVII,

p- 101.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. §17

Petalorbynchus psittacinus—Enniskillen, 1869. ‘Catalogue Type, Spec.,” p. 7.
Petalodus ' Young & Armstrong, 1871. “Trans. Geol. Soc., Glasgow,” Vol. III.,
Supt., p. 74.
- sagittatus— s 1871. ‘Trans. Geol. Soc., Glasgow,” Vol. FUL,
Supt., p. 75.
Petalorhynchus psittacinus | aes : ee i 1876. “Catal. of West Scot. Foss.,” p. 62,
and Robertson,
i es J. J. Bigsby, 1878. ‘Thesaurus Devon.-Carb.,” p. 361.
- s J. W. Davis, 1881. “Rep. Brit. Assoc.,” p. 646.

Teeth, medium size, consisting of, at least, three vertical and five transverse
rows of teeth in each jaw; form much varied in different parts of the mouth
according to situation. Crown generally longer and narrower in central row, and
broader and shorter laterally ; spatulate. Base very long in primary horizontal
row, diminishing in the teeth occupying second and succeeding rows; length of
average specimen, 10 to 1°5 inch; breadth of crown, ‘6 to ‘8 of an inch; length
of crown, anteriorly, one-third that of base ; posteriorly, slightly longer than its
breadth. Crown acutely angular, with a sharp cutting edge, pointed in the
middle, resembling the beak of a parrot; anterior surface laterally convex ;
median portion, from the point downwards, forming a prominent ridge, laterally
expanded and depressed with thin circular margins. Anterior ridge separating
crown from base, extends sigmoidally across the surface; ornamented with four
or five folds of ganoine extending slightly upwards on each side from the central
ridge of the tooth, and recurved towards the lateral margins of the crown, forming
with them an acutely-pointed decurrent angle. Posterior surface deeply concave,
spoon-shaped, nearly twice the leneth of the anterior surface; posterior ridge
covered with an equal number of enamelled folds, continuous with those on the
anterior surface ; from the lateral margins they curve downwards towards the base,
then recurving sigmoidally meet and unite on the median line. Root, like the
crown, varies in form in accordance with the position occupied in the arrangement
of the teeth. Ina typical example from the primary row of teeth, the root is
twice as long as the anterior face of the crown, and from the point of its connexion
with the crown gradually diminishes in diameter to the bottom. On the anterior
surface, the central coronal ridge is continued downwards to the base, at first
expanding in width for about one-third the length of the root, afterwards gradually
contracting. On either side the ridge is a deep sulcus which extends to the lateral
margins. Posteriorly, the root is depressed medially, with a slight ridge on each
side, from which the surface slopes to the lateral margins, termination of base
obtusely angular. The coronal surface is smooth, or very slightly punctate,
enamelled, and highly polished: cutting edge of crown in most cases smooth,
occasionally very slightly imbricated. The crown is frequently worn along the
edge, on one side only, in such a manner that the effect could only he produced
by the grinding action of an opposing tooth, which served at the same time to
''518 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

keep the cutting edge of the tooth sharp. Descending from the apex of the convex
anterior coronal surface there is in some cases a closely approximating series of
open ducts or canaliculze, they are about an eighth of an inch in length and extend
with a slightly sinuous line and not unfrequently bifurcate.

The general resemblance of some of the lower teeth of Petalorhynchus to those
named by Professor Agassiz, Chomatodus truncatus (Pois. Foss. vol. iii. p. 174),
and afterwards described by Professor M‘Coy, asa Petalodont form of Chomatodus
(Brit. Paleeoz. Foss. p. 618, pl. 31, fig. 1), strongly suggests the probability that
the two genera may have appertained to the same fish. They are described by
Professor M‘Coyas being “longitudinally oblong, sides of crown and root sub-parallel,
except at the upper and lower ends, when they rather abruptly converge to form
the subtruncate, slightly rounded cutting edge at top, and the rather more pointed
lower end of the root ; crown flattened, bent at an angle of 120° with the long root
which is nearly straight in profile; surface of the crown finely punctured as in
Psammodus; root, hard and polished, with two or three obscure longitudinal
furrows, almost entirely surrounded by a raised marginal extension of the thick,
prominent, simple, coronal ridge ; the posterior side is concave. Length six and
a half lines, width six lines, length of crown two lines.”

Count Miinster has described a series of teeth of Janassa (Beitrage zur Petrefac-
tenkunde, Heft V. p. 38, tab. 15, fig. 10-14), which appear in all more important
particulars to have possessed great similarity in arrangement to those of Petalo-
rhynchus. In Janassa the terminal teeth are similar in form to certain Petalodonts,
and it may perhaps be assumed that the teeth hitherto known as Chomatodus
truncatus, were the terminal teeth of Petalorhynchus. They differ considerably
in form, but the teeth which are undoubtedly Petalorhynchus, bridge ‘over the
difference between the sharp, long pointed form of the central teeth and those,
even and flat crowned, which occupied each posterior extremity of the jaw.
Awaiting evidence to the contrary they are here included with Petalorhynchus.

Three species of Petalorhynchus are described from the upper beds of the St.
Louis Limestone, of Hlinois (Paleont. of Illinois, vol. VI. p. 405-409, pl. XIL, figs. 1-8).
P. pseudosagitiatus St. J. and W. is described as an example of the intimate specific
relations existing between the European and American Carboniferous fishes. It
very nearly approaches P. sagittatus Agass., from the Limestone of Armagh, but
“ig distinguished by its shorter base, less rapidly converging outline of the crest,
and the more numerous imbrications of the coronal belt.” Considering the extreme
variety in the form, size, and characteristics which exist amongst the numerous
specimens from Armagh, it is slightly problematical if the above differences are
sufficient to constitute a separate species. The same remarks may apply to P.
distorius, St. J. and W., itis possibly a lateral tooth of P. pseudosagittatus, the twist
in the crown being due to its position in the mouth. ‘The third species P. spatu-
jatus is principally characterized and distinguished by its broadly expanded base,
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 519

and is described as holding a similar relationship to P. pseudosagittatus that P.
psittacinnus does to P. sagittatus in the Carboniferous Limestone of Armagh, which
may be correct.

Formation and locality : Mountain Limestone, Armagh.
Hex coll. Kari of Enniskillen.

Genus.—Pristodus, Agass. (MSS.)
Diodontopsodus.—Davis, 1881. ‘“ Rept. Brit. Assoc.,” 1881, p. 646.

Teeth, medium size, beak-shaped, with a semicircular trenchant cutting edge,
upper jaw deeply serrated; crown consists of a vertical surface enveloping the
jaws externally, deep anteriorly and diminishing in size posteriorly on each side;
at right angles to the vertical portion, an expansion of the bony surface forms a
palate, extending backwards to a line with its two latero-posterior extensions,
junction of surfaces produced to form a more or less acute cutting edge. Surface
enamelled, smooth or slightly punctate.

Pristodus falcatus, Agen (MSS.)
(PL LXL., figs. 17, 18, 19, 20, 21, 22.)

Pristodus falcatus—L. Agassiz, 1859. ‘ Enniskillen Coll. MSS.”
Ps E Morris & Roberts, 1862. “ Quart. Journ. Geol. Soc.,” Vol. XVIIL, p. 101.
“ ij Enniskillen, 1869. “Type Specimens of Foss. Fishes,” p. 7.
w 5 J. J. Bigsby, 1878. “Thesaurus Devon.-Carb.,” p. 363.

Teeth. Two forms; in those of upper jaw the cutting edge is largely extended
and divided into a series of ten to fourteen deeply cut serrations, largest in the
centre and diminishing in size backwards. The denticles are triangular in outline,
broad at the base, converging to an acutely poimted apex. In each example the
centre of the tooth, which envelopes the whole external surface of the jaw, is the
line of division between the two largest serrations, one extending on each side ; in
no instance does one of the denticles occupy the median line. The vertical length
of the tooth is ‘5 inch from the upper palatal portion to the extremity of the
serrated cutting edge. It is semicircular in outline, diminishing in height post-
eriorly, and the cutting edge extends obliquely forward from above downwards.
The lower jaw was enveloped in a somewhat similar bony investment, but whilst
in the upper jaw the serrated cutting edge extended from the palatal surface and
formed a long cutting edge, in the lower jaw the cutting edge is not serrated and
extends cnly a short distance beyond the horizontal palate. It is produced and
pointed in the centre, in the form of a beak, from which the surface of the crown
descends on each side, forming only a slight ridge towards the posterior portions of
the tooth. The vertical portion of the lower tooth is slightly convex, its lower

margin extending downwards in front of the jaw, forming an acute point, and from
TRAYS, ROY. DUB, SOC., N,S., VOL, I. aOKG
''520 On the: Fossil. Fishes of the Carboniferous Limestone Series of Great Britain.

this curving graduallysupwards on each side towards the backwardly extended
palate: . The ‘palatal surface is concave, its anterior margin is formed by a semicir-
cular cutting-edge, the posterior margin extends with a shghtly inward flexure
between the two latero-posterior extremities. The teeth consist of a thin bony
shell, the internal surface conforming generally to the external one, and envelop-
ing the cartilaginous jaws. There is no distinct base or root. The surface is
thinly but uniformly coated with enamel, sraooth or slightly punctate.

Messrs. St.John and Worthen, in the ‘Paleontology of Iliinois” (Vol. VL, p. 402,
pl. Xa., fig. 6), refer a minute tooth, -09 inch in lateral diameter, to the genus
Pristodus. Judging from the description and figure, the tooth has the serrated
cutting edge, similar to that of Pristodus, as represented in the teeth from the
Yoredale Limestones of Yorkshire, and it bears a further likeness in having no
appreciable basal region. Leaving its small size out of consideration, it differs
from Pristodus in several important particulars; it does not extend in a semicircular
form backwards at the latero-posterior extremities of the tooth and has much more
the appearance of having constituted one of a series of teeth in the shark-like types,
or, as is suggested by the authors, to one of those curious little fossils known
under the general term Conodonts, than to the singular arrangement in Pristodus.
In the latter there are always two central pronunences or cusps of the coronal surface,
one on each side the median line, which are equal in size, whilst in the specimen
{rom the Kinderhook fish-bed there is only one central prominence. The Yorkshire
specimens are devoid of any imbrications or folds extending along the base of
the crown; they are present in the P. acuminatus, St. J. & W. It is improbable
that this tooth can be retained in the genus Pristodus.

The teeth are probably unique in their characteristics amongst the fishes of the
Paleeozoic rocks. A single tooth appears to have enveloped the whole of the jaw,
upper or lower as the case may be. Those of the upper jaw differed considerably
from the lower. <A strongly-serrated, trenchant, cutting-edge descended from and
encircled the palatal portion of the crown. The serrations, having the character
of a number of teeth or denticles anchylosed together, decrease in size backwards,
the largest on each side the median line of the tooth occupying about one-third its
vertical length ; broadly implanted they converge triangularly to an acute point.

The tooth of the lower jaw is devoid of serrations and presents a surface,
produced to form a single apical point in the centre, but otherwise plain and
gymooth. It is smaller than the upper tooth, and when the mouth of the fish was.
closed, the serrated portion of the latter enveloped the lower jaw extending far
over its anterior surface, this is clearly shown by a specimen in the Collection of
Mr. William Horne of Leyburn. The upper palatal portion of the jaw in this
specimen is broken off, leaving the circular vertical part deeply serrated as usual
and about a quarter of an inch in depth. ‘The interior of the tooth is filled up
with a matrix of limestone, and projecting from this is the pointed apex of the
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain, 521

tooth of the lower jaw. It is situated just within the central part of the tooth of
the upper jaw. The palatal surface of the tooth of the lower jaw is characterized
by considerable lateral convexity; and is produced in front to form the beak-like pro-
minence. Inside each lateral margin, there isa deep sulcus, the palatal and vertical
portions uniting to form an acuminate and well-developed cutting-edge. The
palatal surface of the upper tooth is as nearly as possible the counterpart of the
lower, so that the two surfaces correspond and fit to each other when closed.

The interior of the tooth is hollow, the enamelled osseous part forming a thin
shell-like covering to the cartilaginous jaws. There is no portion which can be
distinguished as the root or base of the tooth, the attachment to the jaw ee ently
being entirely on the inside.

In searching for the zoological relationship of Pristodus, a striking and most
peculiar resemblance is at once observed between it and some of the Gymnodont
group of the Plectognath group of fishes at present existing. These fishes are
characterized by the possession of jaws which in some instances consist of a single
undivided dental plate to each jaw. In others, the dental atrangement. consists
of two upper and two lower dental plates, divided by a mesial suture. The first
group is the one to which the Mountain Limestone fossils bear the greatest resem-
blance. The existing group comprises about seventeen species, which are frequently
found in the Tropical Atlantic and Pacific seas. A common example is Diodon
maculatus, which may be taken for comparison with the fossil forms. It is
unnecessary for our present purpose to consider more than the dental arrangement,
In an example six inches in length from the snout to the base of the tail, the oral
aperture is eight-tenths of an inch in width, and both the upper and lower jaw is
provided with a single semicircular dental plate, extending backwards into the
mouth, in the form of a palate. The front edge is slightly produced and somewhat
beak-like, the teeth extending upwards and downwards respectively, encircling
the outer aspect of the jaw and forming in section two sides of a triangle, the third
side being occupied by the soft internal muscular or cartilaginous attachment for
the tooth. This dental arrangement is admirably adapted to break up masses of
coral, or the hard shells of molluscs and crustaceans on which the fishes feed,
The upper dental plate extends slightly beyond, and overlaps the lower one ; it is
slightly more produced or pointed in the centre. Posteriorly, the upper and lower
jaws are strongly united by ligaments and muscles, the upper extending over and
embracing the lower.

The genus Diodon occurs in a fossil state in the tertiary lmestone of Monte
Bolea and Licata, and from Monte Postale, Enneodon, a distinct genus has been
found and described.

In many respects the fossil teeth from the Mountain Limestone of Yorkshire,
bear considerable resemblance to those of Diodon. In the general form of the

palatal interior, combined with the semicircular external, trenchant edge of the
4K 2
''522 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

tooth, the two are almost identical. The fossil examples do not appear to have
had an osseous prolongation posteriorly for the muscular attachment of the upper
and lower jaw, but this may be due either to the imperfection of the specimens,
which are rarely perfect, or perhaps, more probably to difference in the organization
of the fishes. Diodon is ranked amongst the Teleostean fishes, with an imperfectly
ossified skeleton ; fins mostly soft, skin naked, except where it has developed
osseous spines, the latter capable of extension for the fish’s protection, by the
inflation of its body. The fossil genus Pristodus is represented only by its teeth,
no other portion of its remains have been identified, and it may be inferred that it
was a fish possessing a cartilaginous skeleton, and probably devoid of dermal spines
or appendages. The skeleton being unossified, it naturally results that only the
teeth are preserved in a fossil state.

A comparison of the recent and fossil teeth, however, leads to a natural infsrence
of relationship in some degree, however remote. Evidence is entirely wanting as
to the anatomical structure of Pristodus, and I do not wish to lead to the inference
that it was more nearly related than is warranted by the peculiar similarity of
the teeth. There is a sufficiently special and peculiar adaptation of the jaws and
teeth, of the two groups, to prove that it is not entirely an accidental one, we know
that the teeth of the recent Diodon are admirably suited to the food on which it
exists, for the purpose of breaking the hard coverings of corals or molluscs, and
there is every reason to believe that those of the fossil forms were equally adapted
to preying on the corals, crustacea and brachiopods existing in so great abundance
in the carboniferous seas.

Formation and locality : Yoredale Limestone, Richmond.
Lx coll, Earl of Enniskillen.

Genus.—Cheirodus, M‘Coy.
Cheirodus.—F. M‘Coy, 1848. ‘Ann. and Mag. Nat. Hist.,” 2nd ser., Vol. IT., p. 131.

‘General form of Ceratodus, that is, more or less fan-shaped, thick, flattened,
with the anterior broad margin deeply divided into lobes; but the inner nearly-
straight margin has a small recurved, thumb-like lobe projecting nearly at right
angles from the middle of its length, preventing the mesial junction of the tritors
of each side of the jaw: the inner marginal lobe is the longest; surface minutely

punctured.”—(M‘Coy.)
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 523

Cheirodus pes-ranee, M‘Coy.
(PL DAE, ties. 3, 5a.)

Cheirodus pes-ranee—F. M ‘Coy, 1848. “Ann. and Mag. Nat. Hist.” 2nd ser., Vol. II.,
p. kot.
fe - J, Morris, 1854. “Catal. Brit. Foss,” p. 321.
. i F. J. Pictet, 1854. “Traité de Paléont,” Vol. IT., p. 269.
. F. M‘Coy, 1855. “ Brit. Paleoz. Foss.,” p. 616, pl. 3 a, fig. 9.
oa a Morris & Roberts, 1862. : “ Quart: Journ. Geol. Soc.,” ‘Vol. X VEIL, p. 99.
55 J.J. Bigsby, 1878. ‘Thesaurus Devon.-Carb.,” p. 349.

Teeth, length °65 of an inch, narrow; anterior lobes narrow, prominent, rounded,
arched, separated by deep concave furrows; the inner lobe about a line longer
than the next outer one: at the base of the former, or about half the length of
the whole tooth, there projects horizontally inwards from the inner margin a short,
wide, slightly recurved, flattened lobe, about 1 inch long; posterior part of the
tooth flattened : surface under a lens finely punctured.

This species is founded on a single specimen in the Woodwardian Museum.
In general appearance it resembles the teeth of Ceratodus of the Devonian

rocks.
Formation and locality : Shales in Mountain Limestone, Derbyshire.
Ex coll, Woodwardian Museum, Cambridge

Genus.—Colonodus, M‘Coy.
Colonodus.—F. M‘Coy, 1848. “Ann. and Mag. Nat. Hist.,” 2nd ser., Vol. IL, p. 5.

“Tooth, clongate-conic, very gradually tapering, section round near the hase,
becoming trigonal towards the apex: front even, sides impressed with short,
alternating, transverse wrinkle-like furrows; enamel-like surface smooth, highly
polished, longitudinally marked with few, distant, minute impressed stric ; it
terminates obliquely at the base, the edge being slightly notched or wrinkled: base
forming a short slightly dilated round disc, placed obliquely to the axis of the tooth,
and extending further behind than in front, truncated below, and of a coarse osseous
texture ; medullary cavity about one-third the diameter of the tooth, cylindrical,
from which, under the microscope, the flexuous, distant calcigerous tubes are seen
to radiate directly to the surface, towards which they become gradually finer and
closer.”

Colonodus longidens, M‘Coy.

(PE LATI te, 6.)

Colonodus longidens—F. M‘Coy, 1848. “ Ann. and Mag. Nat. Hist.,” 2nd ser., Vol. IT.,
: p. 0:
- _ J. Morris, 1854. “Catal. Brit. Foss.” p. 323.
F. J. Pictet, 1854. “Traité de Paléont.,” Vol. II., p. 149.

Morris & Roberts, 1862. “Quart, Journ. Geol. Soc.,” Vol. XVIII, p. 100.
J. J. Bigsby, 1878. “Thesaurus Devon.-Carb.,” p. 351.

” 99

” 9
''524 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

Prof. M‘Coy remarks of this species, that it is an almost perfectly straight,
cylindrical tooth, the apex being unfortunately wanting, but enough remains to
show that towards the extremity the anterior face becomes flattened so as to give
an obscurely trigonal section : there are two alternating rows on each side of about
thirteen or fourteen short transverse furrows, forming between them obscure
wrinkles : the whole surface to the naked eye seems smooth and highly polished, but
under a low power, the fine, impressed, rather distant longitudinal sulci become
visible. The whole tooth seems directed backwards at a considerable angle from
its round bony base, and the inferior termination of the enamel-like portion is
therefore very oblique to the axis of the tooth, being considerably lower in front
than behind, the edge seeming: of considerable thickness from a sharp constriction
being immediately under it all round, beneath which again the osseous base
thickens to form a little peltate mass. The length of the portion preserved is °9
of an inch, width at base ‘3 of an inch, diminishing towards the apex to °15 of an
inch.

This peculiar form, at present in the Museum of the Geological Society of London,
which served as the basis of the above description in 1848, still remains unique.
It differs very much from any other teeth discovered in the Mountain Limestone.
Its relationship is considered by Prof. M'‘Coy, to be with Rhizodus or Dendrodus,
and consequently that it is the tooth of a ganoid fish, but the likeness is somewhat
remote, and awaiting further discoveries, it may be as well to withhold any opinion
as to its zoological affinities or position.

Formation and locality: Mountain Limestone, Armagh.
Ee coll. Jones Collection, Museum of the Geological Society, London.

Genus.—Cceelacanthus, Agass.
(Pl. LXIIL., figs. 7-12.)

Several detached plates of a species Coelacanthus have been found in the
limestone at Armagh. They consist of an operculum, jugular plates, mandible, and
other bones of the head as well as some scales. ‘They possess the characteristic
surface ornamention of the genus and probably belong to the species C. lepturus,
Agassiz.

Formation and locality : Mountain Limestone, Armagh,
Ex coll. Karl of Enniskillen.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain, 525,

Genus.—Oracanthus.

Oracan

thus milleri, Agass.

(Plate LXIL, figs. 1-13, Pl. LXIIL, figs. 1-4, Pl. LXTV., figs.1,2, Pl. LXY., figs. 3, 4.)

Ichthyodorulithes curvicostatus,

Buckland and De la Beche, MSS., Bristol Museum.

“ Rech. sur 1. Poiss. Foss.” Vol. ILL., p. 13, pl. iii, figs. 1, 2,3 & 4.

Oracanthus milleri—L. Agassiz, 1833.
. pustulosus, - 1833. i. . 5 v4) Wok DEL, p. Lajae am, Ges. 3, 4.
- minor, a 1833. e Be yp np Wok. WI., p. [Gnpe am, figs. 5, 6:
3 confluens, ee y 1833: - “ wes, - Vol, IED, paeie indet.
i 2 J. E. Portlock, 1843. “ Rept. Geol. Londonderry,” p. 461. _
‘ minor, 1843. % : 9 p- 461.
3 milleri— CO. G. Giebel, 1848. “Fauna der Vorwelt,” Vol. I. pt. 3, p. 303.
i pustulosus, rs 1848. i 5 i Vol. L, pt. 3, p. 303,
& minor, 7 1848. s . es Vol. Js.pt.. 3, p. 309.
5 confluens, - 1848. . j : Vol 1, 3, pt ove.
- - H. G. Bronn, 1848. ‘“ Nomencl. Paleont.,” p. 847.
- milleri, is 1848. e . p. 847.
ee minor, 1848. % is p- 847.
a pustulosus, e 1848. 3 A p. 847.
Coccosteus ? carbonarius—F.*M‘Coy, 1848, “Ann. & Mag. Nat. Hist.,” 2nd ser., Vol. IL., p. 9.
Asterolepis verrucosa, % 1848. a A 5, gudeer,, Vol 20, po.
Platycanthus isosceles, 3 1848. so oe o *, Ome fer, Wor VL. p. bau:
Oracanthus confluens, » 1849. “Enumerator Palont.,” p. 649. ©
is milleri, a 1849. % ' p. 649.
3 minor, - 1849. 5 ‘5 p- 649.
i: pustulosus, 3 1849. 5 is p. 649.
3 confluens—J & Morris, 1854, “Catal. Brit. Foss.,” p. 334.
_ milleri, 3 1854. x o wor poe
F minor, 5 1854. 53 bs 4 ps oon.
pustulosus, oe 1854, we ,, s op ao:
Coccosteus ? carbonarius, _ ,, 1854. i a ee oan.
Asterolepis verrucosa, % 1854, 5 3 5.) pols:
Platycanthus isosceles, Z 1854. 4 5 jou Glineae:
Oracanthus milleri—F. J. Pictet, 1854. “Traité de Paléont.,” Vol. II., p. 284.
is pustulosus, 5d 1854. i 3 Vol. LL, p. 284.
e minor, [ 1854. > Vol. IL, p. 284.
es confluens, s 1854. . Vol. If.,-p. 284.
Coccosteus ? carbonarius, _ ,, 1854. 3 3 MeliEL.,/p.. 225
Asterolepis verrucosa, ; 1854. ‘3 - Vole H,;pe150.
Platycanthus isosceles, os 1854. me ¥ Vol. IL., p. 292
Oracanthus milleri—F. M‘Coy, 1855. “Brit. Paleoz. Foss.,” p. 634.

9)

a milleri,
a minor,

J pustulosus,

confluens—Morris and

Roberts, , 1862. “Quart. Journ. Geol. Soc,” Vol mx Vales pr cut:
: 1862. es yop | Nol SV LE pater,

5 1862. 3 e pit yy SMO OS WITE. spe LOL:
1862. i 4 sictrit on Kae Ouse Atop AOL.

9?
''526 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

Platycanthus isosceles—Morris and
Roberts, 1862. “ Quart. Journ. Geol. Soc.,” Vol. XVIIL, p. 101.
Coccosteus carbonarius, 5 1862. Be 5 . a ol, SV IL1.; p. 100.
Oracanthus milleri— Young and
Armstrong, 1871. “Trans. Geol. Soc. Glasgow,” Vol. III., Supt. p. 73.
e minor, a isl: es i 5 Vol Ait Supt. p, 73.
milleri—Armstrong,
Young & Robertson, 1876. “Catal. W. Scot. Foss.,” p. 62.

53 minor, * 1876. 3 i pop: 62.
= confluens—J. J. Bigsby, 1878. ‘‘ Thesaurus Dey.-Carb.,” p. 359.
s milleri, ve 1878. ri 6 oer} op 09.
9 minor, - 1878. 3 ies (Re O09.
. pustulosus, - 1878. 3 eer pp. 3oe:
Asterolepis verrucosa, 3 1878. ey 5 fib) Pro eds
Coccosteus carbonarius, a SiS: 55 3 She pe 229:
Platycanthus isosceles, 3 1878. a3 et ee alae

Oracanthus millerimde Koninck, 1878. “ Fauna du Calc. Carb. de la Belgique.,” p. 69, pl v., fg, 10;

In the early part of the present century some specimens of a large Ichthyodorulite
were found in the Black Rocks at Clifton, near Bristol, by Dr. Miller. They were
deposited in the Bristol Museum, and were named by Buckland and De la Beche,
Ichthyodorulithes cui vicostatus, they were not, however, described by these authors.
They were considered to be the spines of a fish of Elasmobranch type, the specimens
were of large size, very wide at the basal end, and their exposed surfaces were
ornamented by prominent pustulations. The base did not exhibit evidence of
having been so deeply implanted in the integuments as is generally observed in
_ other genera. Prof. Agassiz described and gave figures of the specimens in his

“« Recherches sur les Poissons Fossiles.” The genus Oracanthus was instituted for
their reception, and the specimens were arranged in three species, being O. pustulosus,
O. minr, and the third in honour of its discoverer, O. milleri.

Oracanthus pustulosus is the largest in size, it is described as being very thin,
much compressed, with a very spacious internal cavity, the external surface is
covered with tubercles disposed irregularly over the spine and most numerous on
the inferior margin. O. milleri is distinguished by the tubercles being arranged
in oblique rows or running into each other so as to form irregularly oblique ridges.
The third species, O. minor, is very small and it is pointed out by Prof. Agassiz,
that it may have been the point of a larger specimen, but that on comparison with
the apex of spines of either of the other species he has found that it is very con-
siderably narrower in proportion to its length; its external appearance it is stated
very much resembles the claw of a crab, but its internal structure certainly indicates
its position to be in the genus Oracanthus.

In addition to the three species from the Bristol Limestone, a fourth was dis-
covered in the Limestone of Armagh, which Prof. Agassiz, named O. confluens, but
did not describe.

Prof.. M‘Coy, considered that O. confluens was the same species as O. milleri,
and also that O. minor was simply the point of the spine O. miller? It is further
''On the Fossi! Fishes of the Carboniferous Limestone Series of Great Britain. 527

remarked that “the extremely puzzling and protean character of the surface pro-
portions, and frequent distortions of this ray are certainly due to its most
extraordinary character, which has entirely escaped M. Agassiz, viz. :—the
extreme thinness of the substance and the great size of the internal cavity.

It is owing to this thin hollow construction that some specimens are flattened
laterally, showing oblique ridges, and some flattened from before backwards,
showing the ridges meeting at a salient angle. This explanation also dispels all
the difficulties under which M. Agassiz laboured, as to the direction of the ridges,
and the position of the faces of the spine.” This statement has been repeated by
M. de Koninck in the “Fauna du Cale. Carbonifére de la Belgique,” (1878.) A
reference to Prof. Agassiz’s descriptions of the species, however, shows quite clearly
that he was well aware of the facts stated by Prof. M‘Coy, whilst the deductions
of the latter, as will be seen by further reference to Pl. LXIV., figs. 1 and 1a, are
evidently fallacious. :

Two or three fragments of osseous dermal plates are described by Prof. M‘Coy
(Annals and Magazine of Natural History,” 2nd Ser., Vol. IL, p. 9), as repre-
sentatives of the Devonian genera Coccosteus and Asterolepis. The latter consists
of an irregular fragment an inch and a quarter long, and less than half an inch wide,
but ‘it is impossible to suggest what part of the body it belonged to.” Two small
specimens are very doubtfully referred to Coecosteus. The several fragments are re-
presented on Plate LXIL, figs. 14, 15; they are from the Mountain Limestone of
Armagh, and form part of the Jones Collection at the Geological Society of London.

Platycanthus isosceles, M‘Coy, (Pl. LXIL., fig. 9), is described by M‘Coy (op. cit.,
p- 120), as a triangular ray, very wide, the length of the base nearly equalling
the height of the spine, arched backwards, much compressed, sides flat, surface.
pustulated, and having two rows of sharp conical teeth on the posterior face.
It very much resembles Oracanthus, but differs in its small size, arched form,
and posterior rows of teeth, which also distinguishes it from Byssacanthus of the
Old Red Sandstone. This species is also from the Limestone of Armagh.

Since the preceding descriptions were written an extensive series of specimens
have been added to the comparatively small number known to Prof, A gassiz ; and
the imperfect specimens which served for illustration in the “Poissons F ossiles,”
cau now be supplemented by others more completely illustrating the characters
and peculiarities of the fishes to which they formerly pertained. Notwithstanding
this increased mass of material there is so much diversity of form, and the structure
of the objects hitherto regarded as dorsal spines is so widely aberrant from the
normal plagiostomous types, such as Ctenacanthus, that, as will be explained here-
after, it is very doubtful whether they can be regarded as spines, and not rather as
the dermal covering of some portion of the body of the fish. It may be advisable
before attempting a detailed description of the specimens to briefly glance at their
general characteristics and more salient points of difference and if possible divide

them into two or more groups.
TRANS ROY. DUB, SOC,, N.S.. VOL. I. ce
''528 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

The Ichthyodorulites described by Prof. Agassiz, and included in the genus
Oracanthus have the following characters in common. Oracanthus pustulosus
and O. milleri are very broad in comparison to their length; the external bony
part is extremely thin and the internal cavity excessively large ; they are laterally
compressed, acutely pointed, and the basal portion, unlike other genera of the
Plagiostomata, is covered to the extremity with the same external ornamentation
which is characteristic of the exposed surface, there being no evidence that any
part of the base was implanted in the integuments of the fish. The «difference
between the two species consisting in the style of ornamentation, O. pustulosus
being studded with tubercles arranged indiscriminately over the surface, whilst on
O. milleri, the tubercles were extended in oblique rows across the surface or
closely approximated, they formed oblique ridges. Oracanthus confluens, which
Prof, Agassiz named in manuscript from specimens in the Enniskillen collection,
was found at Armagh, the two previously mentioned being from the Bristol Lime-
stone. O. confluens may be distinguished from 0. pustulosus and O. milleri by the
extreme width of its base. An example measuring 33 inches on its shorter side,
between the point and the base, is 3°0 inches across the base, so that the width
of the base is nearly equal to the length, whilst in O. milleri the length from point
to base is more than double the basal diameter. The surface is covered with
pustulations which in some specimens assume a definite arrangement, or form ridges
by the coalescence of the tubercles, whilst in others there is no definite arrangement.
Specimens exist which exhibit modifications embracing both these forms,

The type specimen of Oracanthus minor, Ag., which forms a part of the Jones
Collection in the Museum of the Geological Society, at Burlington House, is also from
the Armagh Limestone. Except a quarter of an inch of the upper extremity the
actual specimen has not been preserved, and there is only its impression on the
matrix left. It is represented in the ‘“ Recherches sur les Poissons Fossiles,” Vol.
III., Plate iii, fig. 5. Tt is quite different in form to the other species already
mentioned, and the small portion preserved is not only tuberculated, but very
distinctly striated, the strie being parallel with the length of the spine, and the
tubercles situated in the grooves between the ridges. The latter feature
distinguishes it from Oracanthus, and the general appearance of the spine appears
to indicate a near, if not identical, relationship with Asteroptychius, Ag. From
the above, it may be gathered that the species of the genus Oracanthus, depending,
as they do, on the characters of the surface ornament, are not of sufficent stability
to justify retention, and that one species, O. minor, Ag., must be eliminated from
the genus.

Having thus briefly reviewed the position with regard to the hitherto described
species of Oracanthus, it is proposed to suggest a reconstruction of the genus, which
will, in all probability, entail its removal from the Plagiostomata and its inclusion
in the Placodermie Ganoids.

The figures on Plate LXIL, represent a series of specimens, all obtained from the
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Brita, 529

Armagh limestone, which have external ornamentation more or less characteristic
of Oracanthus. They are of varied form, but all agree in being thin osseous plates,
whose surface is raised so as to form smooth enamelled pustulations similar to, but
smaller than, those on the surface cf the Armagh specimens named by M. Agassiz,
Oracanthus confluens. Amongst this group must be included the examples named
by Prof. M‘Coy, Coccosteus carbonarius, Asterolepis verrucosa, and Platycanthus
isosceles. That this group of specimens formed the cephalic covering of some fish
there can be little doubt. Figures 1 and 2 probably formed the central dorsal
shield ; figs. 4 and 7, the maxilla and mandible respectively ; figs. 5 and 6, the
operculum or cheek plates; fig. 12 has the form of a jugular plate, and fig. 13,
an external bony plate, bent at right angles. The upper triangular portions of
the plate represented in fig. 2, broken or separated from the gencral mass, have
been labelled O. minor, and what appear to be similar fragments have been con-
sidered by American Palontologists as representing a separate genus, Pnigacanthus.
The specimens so named in the collection of Lord Enniskillen are quite different
from the type of the species described and figured by Prof. Agassiz; the latter as
already observed, does not possess the characters of the genus. In addition to
those specimens which are represented on Plate LXUL there is a large number
worthy of very careful study, for the most part similar in form and characters to
those figured, but frequently differing in detail, especially as to form.

Three specimens, from the extreme peculiarity of their form, call for especial
attention. They are apparently similar to each other and may have been the
counterpart organs of three individuals. The largest and most perfect specimen
is 14 inches in length, the basal termination absent. The specimen consists of a
long shaft, compressed from back to front, slightly arched longitudinally. Its
greatest lateral diameter is about an inch towards the basal extremity, antero-
posteriorly it is between °25 and ‘5 of an inch. Nearer the upper extremity of
the specimen the diameter slightly and gradually decreases until about 2 inches
from the extremity where it suddenly expands to 1°75 of an inch, and forms a
more or less spatulate expansion, ending with a broadly rounded margin. The
specimen is composed of a close-grained, fibrous, osseous substance; one of the
specimens shows an internal cavity near the basal end, it is small and conforms
generally to its outer surface; the spatulate extremity appears to be a solid bony
structure. The outer surface is convex, and ornamented with pustulate tubercles,
sometimes indiscriminately scattered over the surface, and at others a short
distance apart, assuming a more or less definite arrangement in gyrating lines ;
the tubercles appear quite similar to those of the external covering of cther parts
of the fish, that is, assuming that the dermal plates already mentioned belong to
the same species. The inner surface of the bone is smooth or striated longitud-
inally with a concavity corresponding to the outer convexity. The lateral portions

formed by the contact of the anterior and posterior surfaces are acutely angular.
L2
''530 On the Fossil Fishes of the Carboniferous Limestone Scries of Great Britain,

The outer or anterior portion of the spatulate extremity is much worn, apparently
by abrasion during the lite of the fish (see figs. 3, 4, on Plate LXV.)

Along with the numerous examples of the external covering alluded to above,
there is in the Armagh limestone a number of ichthyolithes, which were considered
by Prof. Agassiz and others, as the spines of Orthacanthus confluens. On Plate LXIII.,
figures 1, 2, 3, three of these specimens are represented so as to indicate some of
their peculiarities. They are laterally much compressed, more or less triangular in
outline, with one side longer than the others, the junction of the two shorter forming
aright angle. It will also be noted that the specimens are in some cases dextral,
in others sinistral, and it may be inferred from this that they were probably
associated in pairs. The outer surface is covered with considerable uniformity by
amore or less irregularly distributed series of pustulate tubercles, smooth and
apparently worn at the apex, with radiating ridges descending therefrom, and
absorbed in the interspaces forming the general mass of the bone. The tubercles
extend across the surface parallel with the open or basal extremity, sceming to
indicate successive lines of growth. When these rows of tubercles are followed
from the front to the back of the specimen it is observed that they are continuous
and extend evenly and around its surface, but that on the lateral surface the rows
are rapidly diverted towards the pointed apex, whilst on the posterior surface the
lines of tubercles arch sti]] more in the direction of the point. This characteristic
is well shown in Plate LXIII., figs.1,1a. The basal orifice, which is extremely large,
conforms to the outline indicated by the rows of tubercles, the anterior or outer
surface extending much lower than the posterior or inner one. The walls are very
thin and the internal cavity extends nearly to the point.

As already stated these cone-like ichthyolithes have existed in pairs, and it appears
probable that they formed the posterior termination of the body. From the
extension of the hard external covering on one side to a much larger extent than
the other, it may be inferred that those sides with least covering were in juxta-
position and formed the axis of the body from which the two armour-plated
prolongations were expanded. Should this have been the arrangement, the vertical
thickness of this portion of the fish appears to have been considerably greater than
the lateral.

It is not proposed to treat more fully of this part of the subject at present, but
rather to leave for future opportunity, with the hope of increased material, the
elucidation of what now appears to be a somewhat difficult problem in fossil
ichthyology. All the specimens hitherto mentioned are from the Mountain
Limestone of Armagh, and are in the collection of the Earl of Enniskillen.

The specimens of Oracanthus from the Mountain Limestone of Bristol, are longer
in proportion to their diameter across the base than those of Armagh, the average
length being double the diameter, whilst in those from Armagh the length is about

equal to the greatest breadth. In other respects they are similar. A specimen,
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 531

slightly imperfect along the inferior or shorter lateral margin is represented on
Plate LXIV. ; figure la, represents the anterior face, and fig. 1, the posterior, the
shortness of the latter in comparison with the former, and the convolutions of the
rows of tubercles are well shown in this specimen. ‘T'wo sections are also given ;
fig. 1e, represents a longitudinal section, and exhibits the thin, compressed antero-
posterior form, whilst fig. 1b, serves to show its form a short distance from the
basal extremity. It is possible that the two forms from Bristol and Armagh, may
indicate sufficient differences to constitute separate species, but until further in-
formation as to the general character of the whole fish be obtained, it may be better
to regard them as modifications only of one species. The Bristol specimens are
also in the Earl of Enniskillen’s Collection.

The Museum of the Geological Society at Burlington House, contains two
specimens of this genus of very largesize. The locality from which they have been
derived is not known. One of the specimens is preserved to the length of sixteen
inches from the apex downwards, and the base, which is seven inches wide at the
lowest part preserved, is broken and imperfect, and in all probability may have
been several inches longer. The second specimen is also imperfect, it is represented
on Plate LXIV., fig. 2, the part preserved is ten inches in length, and the base
about seven inches wide, its width converges rapidly to about 3 inches, the remaining
portion of the apical extremity is broken off. Both specimens are extremely flat
and compressed, they are cracked and broken in several places, so that the flatness
may be ina great measure owing to the instability of the extremely thin walls
which are little more than the eighth of an inch in thickness. The bony substance
of which they are composed is fibrous and has a strong tough appearance ; the
surface is coarsely pitted in the spaces between the rows of tubercles, the latter
are prominent, enamelled and smooth, and for the most part connected together so
as to form long parallel ridges :25 of an inch apart. The under surface of the bone
is smooth or striated longitudinally. The internal orifice is, of necessity, only
about a quarter of an inch smaller than the external diameter.

These specimens do not differ in any important particular, except in size, from
those of Bristol or Armagh.

Formation and locality : Mountain Limestone, Armagh.
Ex. coll. Ear] of Enniskillen.

Genus.—Stichacanthus, L. G. de Konincx.

Stichacanthus—L. G. de Koninck, 1878. ‘Fauna du Calcaire Carb. de la Belgique,” p. 70.

Professor de Koninck designates under this generic name species of tolerably large
size, having the form of a recurved and depressed horn with a tolerably strong base.
The surface is covered with a numerous series of longitudinal and parallel nodular
riks. The tubercles are prominent, somewhat elongated and attached the one to
''532. On the Fossil Fishes.of the Carboniferous Limestone Series of Great Britain.

the other by the prolongation of the ribs upon which they are fixed. The interior
of the spine is hollow’almost to the summit, ard the walls are thin. The posterior
margin is armed with small spines directed obliquely towards the base. ts

This genus has frequently been associated im collections with (so-called)
Oracanthus, to which in'some respects the specimen now to be described hears a
resemblance. Its walls are thin, with large internal cavity, the long slender form of
this genus is, however, quite distinct from the triangular and irregular outline of
Oracanthus and the tubercles instead of being arranged as in that genus, are placed
in regular longitudinal rows. Prof. de Koninck suggests a resemblance to Physone-
mus of M‘Coy, it appears to be a very superficial one in the present case.

Stichacanthus tortworthensis, Davis.
(PRdaev tor 2.)

Spine, medium size, long and comparatively slender, gently arched, much
compressed, imperfect, basal and apical terminations absent—-part preserved is
eleven inches in length—greatest width near base 2°3 inches, gradually diminishing
to ‘8 of an inch at the part nearest apex which is preserved. A transverse
section is oval, laterally compressed or flattened, the anterior and_ posterior
extremities of the section being more or less pointed. The surface is ornamented
by a numerous series of longitudinal ridges, decreasing by inosculation as they
approach the apex. The ridges extend parallel for the most part with the
concave (posterior?) margin. The ridges are produced at short intervals so as
to form nodular tubercles, broadly implanted, rounded and smooth at the top.
The ridges are separated by longitudinal furrows, which are again subdivided by
minute striations especially towards the basal extremity. The walls of the spine
are thin, and the internal cavity large. The basal portion which may have been
implanted in the body of the fish is not preserved. Along the convex margin of
the spine the tubercles are larger than on the sides, and present the appearance of
denticles : the tubercles on the concave margin do not present any special feature.

This species differs from Stichacanthus cemansi, de Koninck, by its length being
considerably greater in proportion to its diameter at the basal extremity ; in the
smaller size of the dermal tubercles, the longitudinal ridges being narrower and
more numerous ; and in the subdivision of tae ridges by strie.

I have ventured to designate this species by the nomen triviale derived from the
locality where the specimens have been found, which was in the immediate vicinity
of Tortworth Court, the seat of the Earl of Ducie, to whom I am indebted for the
opportunity of describing the specimens included in this genus, and the great spine
for which I have been obliged to establish the following genus.

Formation and locality: Mountain Limestone, Tortworth.
Ew coll. Earl of Ducie, Tortworth Court.
''On_-the Fossil: Fishes of the Carboniferous Limestone Series of Great: Britain, 533,

Genus.—Phoderacanthus, Davis.

Spine, very large size, strong, gently and gracefully arched, wide at the base,
gradually tapering to an acute apex ; transverse section, more or less oval, com-
pressed laterally towards the basal extremity, internal cavity wide, opening
terminally ; posterior cavity or groove absent, no posterior denticles ; surface
uniformly covered with large smooth tubercles arranged on longitudinal ridges
and also to a greater or less extent forming lines across the spine. Osseous walls
of the spine pierced by several cylindrical canals extending longitudinally parallel
with the surface. Base not preserved. |

The magnificent specimen which forms the type of this genus, is perhaps the
largest example of a fin-defence hitherto discovered. The imperfection of the
base renders necessary an addition of at least several inches to its length, and there
is thus indicated a truly formidable and terrible weapon of offence, nearly or quite
three feet in length.

The genus Antacanthus, Dewalque, in several respects appears to possess
characters similar to those of the genus now described. They resemble each
other in the arrangement of the tubercles on the surface and in the possession of
large cylindrical canals in the mass of the bony structure of the spines, but there
is a great divergence in the form of the transverse section of the spines of the two
genera; in the absence of large denticular tubercles on either the convex ‘or
concave margin of this one; and above all in the character which gives the name
to the genus Antacanthus. Prof. de Koninck considers that the direction of the
line dividing the exposed from the embedded portions of that species, Showing its
oblique implantation in the body, the line of demarcation forming an obtuse angle
with the convex surface of the spine, and an acute angle with the concave surface
which is the opposite of the arrangement in such genera as Ctenacanthus or
Gyracanthus, indicates that the convex margin was the posterior one, and the
concave the anterior one. The genus now introduced does not appear to diverge
from the ordinary types of plagiostomous fishes, though the basal extremity of the
spine is wanting, the rows of tubercles, already described as extending across the
spine, no doubt indicate the line of demarcation to a large extent, and this being
so, it is evident, that the line would form an acute angle with the convex border,
and an obtuse one with the concave in the ordinary way.

With the genus Oracanthus, with which this specimen has been erroneously
associated to the present time, it possesses little in common except its pustulate
surface; and in the character of the pustulations a comparison of the two will
prove that they are quite distinct. The long comparatively slender and graceful
form of this gerus, its thick convex walls, and arched form, are altogether different
from the thin compressed section of Oracanthus, with its great basal opening and
rapidly converging antero-posterior margins. In the peculiar duplicate arrangement
of the spines (?) of Oracanthus, there is a still greater divergence from anything
analogous in the form of this genus.
''534 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

Phoderacanthus grandis, Davis.

(Pl. LXV., fig. 1.)
Oracanthus pustulosus—MS. in Collection of the Earl of Ducie.

Spine, very large, massive and strong, gracefully arched, devoid of posterior
cavity, or external groove. Imperfect at the basal extremity and exhibits no
basal surface indicating the extent of its insertion in the integument of the body. The
length of the part preserved is 27 inches; the diameter near the base is 5 inches,
it gradually decreases towards the apex ending in a point. The surface of the
spine is much fractured and broken, but sufficient remains intact to show the
nature of its ornamentation. Transverse section more or less oval, inferior margin
rotund, lateral ones convex, gradually converging to form a superior margin
slightly less rotund than the inferior one. Near the apex the section is much less
compressed than it is near the base, the latter appearing to be somewhat crushed.
The internal cavity is large and conforms generally to the external surface. The
walls of the spine are about ‘5 of an inch in thickness, except on the superior.
margin where they are somewhat thicker. The surface of the spine has been
uniformly ornamented with a series of pustulate ridges, extending in longitudinal
rows; the pustulations also extend in close lateral contiguity one with another
forming a continuous, somewhat wavy ridge across the spine, less regular and
slightly smaller near the apex than below. The pustulations are smooth, prominent,
broadly and firmly implanted in the body of the spine. There is. no distinct
evidence of either superior or inferior margin having possessed any denticular
processes larger than the pustulations occupying the general surface.

The osseous substance of the spine is hard, compact and fibrous. It is pierced by
longitudinal cylindrical canals which appear to have served the purpose of conveying
the nutrient juices from the base towards the apex of the spine. The most
prominent and largest of these canals is situated midway between the external
surface of the superior margin and the large internal cavity ; it is ‘1 of an inch in
diameter ; others occur in the substance of the spine, along the lateral margins
and may be distinctly recognised in several places where a portion of the outer
surface of the spine has been removed.

M. de Koninck, in the description of Antacantius insignis, Dewalque, from the
black limestone of Liege (‘‘ Fauna du Calcaire Carb. de la Belgique,” p. 74), notes the
passage of a cylindrical canal in that species similar to the one described above in
the superior portion of the spine, but he does not mention others.

Formation and locality: Mountain Limestone, Bristol.
Fixe coll. Earl of Ducie, Tortwerth Court.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain 535

3. Description oF LOCALITIES.

Before giving a detailed description of the several localities in the British
Islands in which the Carboniferous Limestone has been proved to contain remains
of fossil fishes, it may be worth while to briefly summarize what is known of the
general character and constitution of the formation as a whole. In Derbyshire
the limestone is a pure, thick-bedded and massive rock, probably two or three
thousands of feet in thickness with occasional but very thin beds of shale. Similar
characters prevail in the neighbourhood of Clitheroe, in Yorkshire, and the lime-
stone has been estimated to attain even a greater thickness than in Derbyshire.
northwards and southwards of these localities the limestone becomes much thinner
and gradually assumes a different character. The massive limestone of Derbyshire
is diminished southwards in Leicestershire to little more than two hundred feet
in thickness and is intercalated with thick beds of shale ; still further southwards
the coal measures of South Staffordshire rest immediately on the silurian rocks,
and the Carboniferous Limestone is entirely absent. From Clitheroe northwards
the limestone diminishes in thickness to 600 feet beneath Ingleborough and a few
miles further, in Wensleydale, has lost its thick-bedded character and is divided
into a number of beds of thin limestone with numerous intervening strata of shale
and sandstone, whilst in Northumberland, still further northwards on the southern
flank of the Cheviot Hills, the shales and sandstones have increased to an enormous
thickness and the limestone has almost entirely disappeared, represented only by
a few thin bands. In Cumberland a similar decadence may be traced, throughout
the whole of this district, where the base of the thick limestone has been exposed,
it is found to rest unconformably on the upturned or contorted beds of Lower
silurian rocks. The junction of the two may be seen to advantage in the
neighbourhood of the Great Craven faults in Yorkshire; as for example, at
Monghton Fell in Ribblesdale, at Norber or at Thornton Force beneath Ingle-
borough. The silurian rocks are in all instances bent and folded at a high inclination,
the whole denuded down to an even surface on which the limestone is deposited.

In Ireland the Carboniferous Limestone is very largely developed, and consists
for the most part of three divisions; there is a thick, pure limestone at the base
and the top, and between the two a middle division which is more or less mixed
with shales or sandstones, the limestone is also impure and earthy. In the
Kilkenny district the limestone is pure and massive, reaching to two or three
thousands of feet in thickness. To the southwards and south-westwards it
thins out and is gradually replaced by shales in counties Waterford and Cork,
and still further to the south entirely disappears, and its place is taken by
thick masses of coarse gritstone. Northwards, at Armagh, the limestones are thin

and divided by beds of shale and sandstone, and towards the highlands of Donegal

TRANS. ROY. DUB. SO0:, N:S:, VOL. LE 4M
''536 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

aud Connemara, the limestone is interleaved with shales and sandstones, with
occasional beds of thin coal, In Ireland as well as England the limestone rests on
the denuded edges of silurian grits and slates, sometimes with the intervention of
conglomerates or sandstones, sometimes without. In each the limestone is very
thick and massive in the central portions of its area, and their northern and southern
portions become intercalated with beds of shale and sandstone, which gradually
increase in thickness towards the boundary line, the limestone at the same time
becoming thinner bedded and finally disappearing.

The Carboniferous Limestone in Scotland occupies the lowland country between
the Grampian Mountains and the border hills. ‘The series is divided into two
parts—the Lower or Calciferous Sandstones, and the Upper or Carboniferous Lime
stone. The former consists of an extremely irregular series of sandstones, shales,
limestones, and thin beds of coal, about six hundred feet in thickness. The Car-
boniferous Limestone series is composed of alternating beds of shale and sandstone,
with several layers of thin limestone. The greatest development is at Beith, in
Ayrshire, where the limestone is about forty feet in thickness. Beds of clay-ironstone
are of frequent occurrence, especially in the upper portions. The Northumberland
district resembles that of the Scottish group to a large extent ; they are composed
almost entirely ot sandstones and shales, with occasionally thin limestones and coals.

In the district around Armagh, from which the majority of the fish remains
described in the preceding pages have been obtained, the Carboniferous Limestone
series overlie the grits and slates of Lower Silurian age, the equivalents of the Bala
or Carodoc Beds of Wales ; the series consists of—

Upper Limestone,

Calp or Middie Division,
Lower Limestone,
Sandstones.

Lower Silurian.

R. Callan. Armagh. S.E.
i

 

 

 

Fic. 1. Secrron rrom §.E. or Armacu, To N.W. or BENBURB CASTLE.

a. Silurian strata. ce. Calp or Middle Series. e. Permian Beds.
b. Lower Carboniferous d. Upper Carboniferous 7. Bunter Sandstone.
Limestone. Limestone. g. Drift.

Horizontal scale, 1} inch to 1 mile. Vertical scale, 43 irches to 1 mile.
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 537

The following description of the Mountain Limestone in the neighbourhood of
Armagh, is derived from the explanatory memoir, sheet 47, of the Geological
Survey of Ireland. The Lower Limestone of the Carboniferous series consists
chiefly of light gray crystalline limestones, sometimes possessing a slight bluish
tinge, and in certain localities assuming a deeper brown and reddish shades. The
beds are in most places separated by thin layers of dark eray shale. The limestone
is generally highly fossiliferous, many of the beds containing large bunches of
coral, crinoidal fragments, shells, and especially towards the base, fish remains.
It is from these beds that the typical specimens of the Jones’ and Enniskillen
Collections have been obtained, as well as the great bulk of the latter magnificent
collection now deposited inthe New Natural History Museum at South Kensington.
Cherty bands are occasionally met with. The thicker beds of limestone supply
very good building stone, which has been extensively quarried in some parts. In
the neighbourhood of Armagh, some of the lower beds have been worked and
polished for marble. These furnish a close-grained rock, which, being of a pinkish
or purplish brown and gray colour, beautifully spotted, and clouded with various
tints of yellow and brown, and susceptible of a high polish, is well adapted for
ornamental work. Some of these beds are flagey, and have been used in the
streets of Armagh. The limestone is in many localities burned for lime of an
excellent quality, which is principally used for agricultural purposes. <A bluish
limestone at Benburb, is said to produce lime possessing hydraulic properties.
This was used in the bridges over the Ulster Canal. Occasional beds of yellowish
and light reddish silicious sandstone occur in various parts of the district, inter-
stratified with the limestone, and these have in some places been quarried for
building.

The Calp consists of sandstones, blue shales and earthy limestones. They are ex-
posed south-west of Benburb. Thin seams of coal occur. The shales are replete with
fossils and the sandstones contain remains of plants as well as mollusca. The Upper
Limestone in this district is thin, ight grayin colour and somewhat arenaceous, and is
shown in the section, figure 1 d; a small thickness of gray arenaceous limestones of
the upper series is exposed near Benburb.

The Lower Limestones are extensively quarried for building and burning for lime.
In a quarry on the west side of the road from Armagh to Loughall, a mile and a
quarter south-west of the latter place, the beds consist of thin bands of light
brownish compact limestone, with layers of dark reddish sandy shale. Tish
remains are found in the latter, and both are largely composed of shells. The
largest quarries lie south of Armagh, near Red Barn. About a mile from the
city in that direction a quarry contains beds of limestone from one to five feet
thick; the rock is a light yellowish or pink colour, and crystalline. Numerous
corals with large masses of Lithostrotion occur, crinoid stems and the shells of
molluscs are coramon, and ‘fine specimens of fish remains have been procured.

Similar fossils have been obtained in a large quarry near the ancient entrenchment
4M 2
''538 On the Fossil Fishes of the Carboniferous Limestone Series of Great Briton.

called Navan Fort, one mile anda half west of Armagh. The face of the rock
worked is sixty feet in height. The fish remains are found principally in the upper
beds.

At Tullyard,west of Wilson’s Bridge,on the Ulster Railway, the Lower Limestone
is extensively quarried: the beds dip S.W., at an angle of 30° to 40°. They have
the usual character of the limestone in this district, varying from one to three
feet in thickness separated by shales. The limestone ranges from a bluish gray
to a brown colour, and is mostly of a crystalline texture. It contains numerous
fossils.

The Carboniferous Limestone of the South-eastern portion of Ireland presents
some variations from the series of strata composing the formation around Armagh.
It consists mainly of three groups (see the section fig. 2), but the lower Limestone
is frequently dolomitized either by the admixture of carbonate of magnesia during
deposition or by a subsequent change in its character. The Limestone Series are
separated from the Silurian beds by great thicknesses of Old Red Sandstones,
attaining in some instances wa vertical extent of more than 3,000 feet. These rest
unconformably on the Silurian rocks, whilst above the sandstones are an additional
200 feet of shales beneath the base of the limestones. The following is the series
as developed in the district around Wexford and Waterford.

Upper Limestone.

“Calo “series.

Lower Limestone (sometimes Dolomitic.)
Lower Limestone Shale.

Upper Old Red or “ Yellow Sandstone.”

Old Red Sandstone.

Lower Silurian Beds.

The Old Red Sandstone is composed for the most part of breccias and conglomerates
of well-rounded pebbles of grits, slates and quartz cemented together, with occasional
thick beds of shale and sandstone of a reddish-brown colour. Above these are the
yellow sandstones separated by an arbitrary line, indicated by a change in colour ;
they vary from 200 to more than 500 feet in thickness. Occasionally the remains
of plants are found in the shales of the Yellow Sandstone series. .

The uppermost beds of the Yellow Sandstone series at Hook point pass gradually
into the Lower Limestone shales, and from them into the Lower Limestone. The
yellow and greenish sandstone and shales change to dark gray, sandy, calcareous
shales and thin grits, alternating with occasional seams of black chert and impure
gray limestone. ‘These are followed by limestones, and in a thickness of about 200
feet the shales and sandy portions disappear altogether. The beds are throughout
fossiliferous, Spirifer, Orthis and Strophonema, Encrinites and Fenestella serving to
distinguish the beds of Carboniferous age. The Lower Limestone is generally
crystalline, thick-bedded, regularly jointed, and of a dark gray colour. In some
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 539

localities the rock is more or less flaggy, as at Granny Castle and Dunkitt, N.W.
of Waterford, where there are large quarries. It also changes to a dolomitic or
magnesian limestone, and where this has occurred the limestone becomes of a pale
brown colour and saccharoid texture; it loses its bedding and all traces of fossils
disappear. The thickness of the Lower Limestone is estimated at not less than
700 feet.

Several species of fossil fishes have been found in the Lower Limestone of
Hook Point and besides these, a greater variety of fossil mollusca, encrinites, and
corals than is to be found in many localities. Mr. W. H. Baily, Palzeontologist to
the Irish Geological Survey, gives this description of the limestone and its fossils :—
“Nothing can exceed the beauty of these fossils where the beds are exposed and
weathered, as they are nearly all round the shores of this point. The rocks of
dark, nearly black limestone are almost horizontal, and rise by a succession of
steps from the sea, with great fissures or joints interrupting the continuity of the
beds. The surfaces of these beds are crowded with Corals, Polyzoa, Brachiopods,
and Crinoids, and sometimes fish-remains. The delicate network of the Reteporide,
and elegant structure of other kinds of Polyzoa, with the internal arrangement of
the Brachiopod shells and the graceful Crinoids, with stems, arms, and heads
attached, are all displayed in perfection at this favourite locality ; and 1 know of
no other place where such a fine field is open for investigating the structure of
these particular groups of fossils i situ as this place affords.”

The Middle Limestone or “ Calp” is composed of compact, evenly-bedded lime-
stone, dark gray or black in colour, with occasional layers and nodules of black
chert and beds of earthy shale, they are occasionally finely crystaJline and reach
500 feet in thickness. The Upper Limestones are generally similar in character
but of a light gray colour, and contain white chert as well as black. North of
Clonmel this group is about 400 feet in thickness,

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Fic. 2. Section FRoM WATERFORD, NEAR Dunxirv, To Tory Hitt.
a. Silurian Rocks. d. Lower Limestone Shale.
b. Old Red Sandstone. e. Lower Limestone.
c. Yellow Sandstone.

Horizontal Scale, 1 inch—1 mile. Vertical Scale, 3 inch=1 mile.
''540 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

Bristol.—The Carboniferous Limestone in this district underlies the Bristol Coal-
field, and rests conformably on the marls and sandstones of the Devonian or Old
Red formation. It consists of the following members :—

Millstone Grits and Coal Measures.
Upper Limestone Shales.
Carboniferous Limestone.
Lower Limestone Shales.

Old Red Sandstone.

The junction between the Old Red Sandstone and the lower beds of the Limestone
Shales is an almost imperceptible one, and can only be discriminated by the gradual
insertion of thin beds of calcareous shales and the presence of fossils of purely
Carboniferous types. The section exposed on the banks of the Avon, near Bristol,
exhibits the whole series as developed in Somerset and Gloucestershire, and as it
is from the quarries near the river that rearly all the fossil fishes have been
obtained, a short description of the Avon section may serve the purpose at present
in view.

The north-western extremity of the section, near Cook’s Folly, is composed of
Devonian sandstones and marls of a red colour. Towards the upper part a quartzose
conglomerate occurs, and about thirty feet above this is the first bed which exhibits
a decided admixture of carbonate of lime. The base of the Lower Limestone
shale series may be placed somewhere between the two, though it is quite
impossible to determine its exact position. The limestone shales are about 500
feet in thickness, and are throughout more or less fossiliferous. They consist of
shales with thin beds of limestone. About 100 feet from their base there is a thin
breccia four or five inches in thickness; when freshly broken it has a grayish
brown colour, which quickly changes by exposure to dark reddish brown from the
oxidation of the iron it contains. The breccia is replete with fossil fish palates, and
some coprolites have been found which contain the comminuted remains of the
hard coverings of mollusca. Numerous shales and limestones with characteristic
fossils occur between the breccia and a second stratum, which is remarkable for
the presence of remains of Oracanthus associated with remains of Brachiopods.
The bed is an argillaceous limestone which weathers easily, and the fossils are in
consequence more easily and perfectly separated from the matrix. It is nearly
200 feet above the breccia, and about the same depth below the Carboniferous
Limestone proper. The latter attains a thickness, in the Avon section, of 2,000
feet, and may be studied in the Black Rock and Great Quarries. The change from
the lower shales to the thick limestone is very gradual, and it is impossible to
draw a distinct line of demarcation between the two. The limestone in the Black
Rock Quarry is very dark in colour, due to the presence of bitumen. The latter
is occasionally so abundant as to be distinctly recognised by the smell. The strata
are very regularly and uniformly bedded, dipping at an angle between 20° and 30° to
the 8.S.E. In the Black Rock Quarry, about 100 feet above the base of the
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 541

limestone, are three beds which are easily distinguished by their remarkably
parallel and symmetrical arrangement. These are the fish-beds of the limestone,
as distinguished from those already mentioned in the Lower Shales. It is from
these beds that the magnificent spines of Ctenacanthus major, Ag., have been
obtained ; the great teeth of Psammodus aud numerous others have also been found
here. Beyond the fish-beds a number of interesting beds occur, a series, about 167
feet in thickness, are Oolitic in structure. The limestone in the Great Quarry is a
lighter gray in colour; between the beds there is frequently a deposit of crystals
of fluor spar.

Above the thick limestone there are about 400 feet of upper limestone shales
which pass gradually into the millstone grits, 1,000 feet in thickness.

The following section exhibits the series of strata between Cook’s Folly and the

Black Rock Quarry :-—

N.W: Cook’s Folly. : Black Rock Quarry. S.E.

   

 

       

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Fic. 3, SECTION IN THE AVON VALLEY, NEAR BRISTOL.
a. Mountain Limestone. 6. Lower Limestone Shales. c. Old Red Sandstone.

The Farlow and Oreton Limestone forms an outlier of small extent at Titterstone,
Clee Hill, in Shropshire. The hill rises from a depression of the Old Red Sand-
stone near Cleobury, and its flanks exhibit the whole of the Carboniferous series
as developed in that district. Above the Old Red Sandstone are the Carboniferous
Shales and Limestone, surmounted by the Millstone Grits and Coal Measures, which
are capped by a considerabie mass of basalt which has been forced by volcanic
action through the entire series and overflowed the top of the hill. The following
sketch from Murchison’s “ Siluria” very clearly exhibits the series :—

QOS

ad SS WTA PA

   

 

 

Fic. 4, Section AcRoss LitTERSTONE, Cire HILL, SHROPSHIRE (AFTER Murcuison).
a. Old Red Sandstone. d. Coal-measures.
6. Carboniferous Shale and Limestone. e. Erupted basalt.
c. Millstone Grit.
''542 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

The thin beds of limestone forming the base of the Titterstone Clee coalfield are
continued in a north-easterly direction, and well exposed at Oreton and Farlow.
The Carboniferous Limestones there overlie a series of yellow sandstones which
constitute the upper beds of the Old Red series. At Oreton the limestone is
extensively quarried, and affords good sections of the general thickness and character
of the limestone. The beds are thicker than at Farlow half a mile distant, though
the arrangement is the same. ‘The middle and lower portions of the limestones
are the most fossiliferous. The principal fossil remains are those of Brachiopods,
Spirifer and Rhynconella being most abundant. Bryozoan remains are numerous
and those of Crinoids and a Crustacean have been found. The most important
remains, however, are those of the fishes, which have been described in preceding
The fauna indicates a deep-sea condition.

The series of Oolitic Limestones exhibit similar structural agencies in their
formation to those of the Carboniferous Limestone of Bristol, and that of the margin
of the South Wales coalfield. The “Jumbles” or Clee Hill marble, has been worked
for decoration purposes, it is the thickest of the Oolitic beds. The accompanying
sketch (fy. 5), will exhibit the relative positicn of the beds in the Oreton and Farlow
district. The fish remains were got from the gray Oolitic Limestone near the
base of the section.

 

Section showing the Mountain LimesTonx at Fartow, in SHROPSHIRE (from Morris and Roberts).

1. Yeilow Sandstone with concretionary masses of Limestone.
2. Gray Oolitic Limestone (from which large palatal teeth were got), 3 feet 6 inches.
3. | Sandrock with nodules of calc spar, 2 feet.
Gray Oolite Limestone (Jumbles), 4 feet 6 inches.
. Soft sandy rock and clays with feruginous beds, 4 feet 6 inches.
. Black clay, 4 inches.
. Gray Limestone, very shelly, 1 foot.
. Brown clays 2 feet, dip about 60° S.E.
. Gray crinoidal Limestone, with bryozoa, 4 feet 6 inches.

oOo ON ea OF

. Dark gray clays with concretionary Limestone, 6 feet.
10. Sandy beds with thin beds of Limestone, 3 feet.
11. Thin bedded bands of sandy Limestone, with concretions of argillaceous Limestone.

Derbyshire—The Mountain Limestone in Derbyshire is generally a pale gray,
thick-bedded and massive deposit of carbonate of lime, it contains a few partings
of shale and clay, and some beds of volcanic origin called “ toad-stone.” Its base
has never been reached, but its thickness is estimated at 4,000 to 5,000 feet. .
The limestone occupies a large extent of surface, reaching from Bakewell to
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain, 543

Buxton, Matlock and Castletown. Above the limestone there is a series of shales
and gritstones, about 500 feet in thickness, which are the equivalents of the
Yoredale series of Wensleydale. It is principally from the black shales im-
mediately overlying the thick Mountain Limestone, that the remains of fishes are
obtained in this district. In no instance are they plentiful.

In Yorkshire the Mountain or Carboniferous Limestone is very largely develop a
attaining its greatest thickness in the district around Clitheroe. It is there
extensively quarried, and the remains of mollusca, bryozoa, and encrinites are
abundant but fish remains have not been found ; at Skipton one or two examples
of the teeth of Lophodus have been discovered, and at Settle, where the limestone
is exposed along the line of the Craven fault, and quarried, the teeth of several
species of fishes have been discovered. The principal locality in Yorkshire,
however, is near Leyburn, in Wensleydale, in the uppermost beds of the formation.
It has ‘already been observed that the thick-bedded, massive limestone of the
districts named above, as they extend northwards, become divided by the inter-
lamination of wedge-shaped beds of shale and sandstone into several thinner beds,
forming a somewhat complex series to which the late Prof. Phillips applied the
term ‘‘ Yoredale Series.” The following section gives approximately the series as

it occurs in Wensleydale :—

Millstone Grit Series, : : : ; : : ; ; — feet.
Red Limestone, : : 3 é d ; : ‘ 20 to 40 feet.
Shale, . : : : : ; 5 : ; 3 —
Main Limestone, : : ; : ‘ ‘ ; : 60 feet.
Grits, Coal and Shale, . : ; : j ; : : 30,
Underset Limestone, : ‘ ‘ ‘ ‘ : 30}
Laminated Grits, flagstones and ace with band of impure productal limestone, 300.5
Middle Limestone, : : ; : : : : ; 303
Gritstones and flags, : : : : ‘ : : DO
Simonside Limestone, ‘ : : ; : ; ; 203
Flags, Shales and Grits, . : : A ‘ . 3 «(i oh 0O..5,
Hardrow Limestone, ; ; : : ; : : : 40,
Grits, Shales and Ironstone,’ _.. ; : : : . @ oe EOD
Lower massive or Scar Limestone (exposed), . : . . «2p

The uppermost limestone, locally named “ Red Beds,” is the one from which a
very large majority of the fossil fish remains have been obtained, which are known
to occur in the Yorkshire beds. A few have been found in the main limestone of
the same district.

In Northumberland the Carboniferous Limestone formation becomes still more:
divided into alternations of limestone, sandstone and shales than in the north of
Yorkshire. It lies, without the intervention of the Old Red Sandstone series, on
the contorted and denuded edges of the Silurian rocks. The strata of Carboniferous

age, beneath the millstone grits have been divided into two groups; the lower,

TRANS. ROY. DUB. SOC., N.S., VOL. 4N
''544 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

named by Mr. G. Tate, the Tuedian, consists of red sandstone conglomerates,
surmounted by red sandstones, and above them beds of limestone, shales, and
clays, the uppermost bed being the Dun or Lamberton limestone, the whole are
about 1,500 feet in thickness. The Upper group, several thousands of feet in
thickness, for which the name Bernician beds has been suggested by Prof. Lebour,
occupy a large area in the western part of the county, extending from the Cheviot
hills and the sea coast at Berwick and Alnmouth, southwards to Hexham. The
Bernician beds are the equivalents of the Yoredale rocks of North Yorkshire and
the thick-bedded scar limestone of Settle and Derbyshire. The Yoredale series
in their progress northwards are largely developed. Thick massive grit rocks are
intercalated with numerous beds of light bluish grey limestone, thick beds of shale
and thin seams of coal. Fossils, principally mollusca of the ordinary Mountain
Limestone species, are numerous throughout the limestones; crinoidsand foraminifera
are not uncommonly met with. ‘The ‘four fathom limestone” and the “great
limestone” are extensively quarried at Lowick and along with a great number of
species of invertebrates, several species of fish have been discovered.

The Carboniferous Limestone series of the west of Scotland assume an entirely
different arrangement to that of the beds in England or Ireland. The massive
Scar Limestone is absent and a large portion of the beds are of fresh water or
brackish origin. The following is the sequence of the beds beneath the Millstone

grits —
Upper Limestone Series.
Lower Coals and Ironstones.
Lower Limestone Series.
Calciferous Sandstone Series.

Old Red Sandstone.

The Upper Limestone Series are between 506 and 600 feet in thickness and
consist principally of thick sandstones, shales, clay ironstones and coals, with
several beds of impure limestone; organic remains are abundant,consisting principally
of mollusca, crinoids, foraminifera, corals, polyzoa and some fish remains. The
Lower Coals and Ironstone are nearly related in lithological characters with the
Upper Coal Measures. They are, with slight exceptions, of freshwater or terrestrial
origin, consisting of sandstones, numerous bands of clay ironstone, shales and
coals. The Lower Limestone Series most nearly approaches the Mountain Lime-
stone in paleontological characters. It ranges from 600 to more than 1,000 feet
in thickness and its lithological character is somewhat similar to that of the Upper
Limestone Series at Beith in Ayrshire, some of the beds of limestone attain a
thickness of more than 40 feet, but generally they are much thinner. One or two
workable beds of coal, and numerous bands of clay ironstone, occur in several
horizons of the strata. In some districts, as at Campsie, thin beds of estuarine, or
''On the Fossil Fishes of the Curboniferous Inmestone Series of Great Britain. 545

freshwater limestone, containing ostracoda and other organisms belonging to
species that occur in the Upper Coal Measures, alternate with the coal beds and
marine limestone. The fossils of the marine limestones and shales are numerous,
and consist of plants, foraminifera, sponges, corals, crinoids, crustacea, polyzoa,
shells and fish remains.

The Calciferous Sandstone Series are 1,500 to 1,800 feet in thickness and consist
in the upper division of a great thickness of bedded traps and ash beds, on which
occur occasional beds of sandstone, impure coal and shale, enclosing plant and fish
remains. Conformably with the ash beds, in descending order, are the Ballagan
Limestone series, consisting of numerous dolomitic limestones, greyish white sand-
stones, flagey sandstones, shales and marls, which contain remains of plants and
occasional fish scales which indicate fresh water origin. Beneath the Calciferous

Sandstones are the Old Red Sandstones.

4, List or GENERA AND Species, with Locauittiss.

 

Salop,
Rene

Armagh : Oreton ; Derby-
Name. , | Bristol. ’? /Yorkshire cae West-
Ireland). ; i ne
( ) and shire. | orelan ad Scotland.| N.W.

Farlow.

 

 

 

 

 

 

 

HYBODONTIDA,

Ctenacanthus major, Agass.,
tenuistriatus, Agass.,
heterogyrus, Agass.,
brevis, Agass.,
denticulatus, M‘Coy,
limaformis, Davis, :
salopiensis, Davis,
dubius, Davis,
levis, Davis, .
plicatus, Agass.,
sulcatus, Davis,
pustulatus, Davis, .
crenulatus, Agass. 5
3 (Onchus) rectus, Agass.,
Acondylacanthus Colei, Davis, :
tuberculatus, Davis, .
3 (Ctenacanthus) distane, M‘Coy,
tenuistriatus, Davis, .
» (Leptacanthus) junceus, M‘Coy,
Jenkinsoni, M‘Coy, .
attenuatus, Davis,
Asteroptychius ornatus, Agass.,
Compsacanthus carinatus, Davis,
Cosmacanthus marginalis, Davis, .
carinatus, Davis, .
carbonarius, M‘Coy,
priscus, Davis,
Lispacanthus retrogradus, Davis, .
gracilis, Davis, ° ;
Dipriacanthus Stokesii , Agass. B
Homacanthus microdus, M‘Coy, .
macrodus, M‘Coy, .
Gnathacanthus triangularis, Davis,
striatus, Davis,

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''546 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

 

 

 

 

 

 

 

 

 

 

 

 

TABLE—continued.
Salop, K
Armagh ; Oreton, z Derby- endal, Ww. Lowick
Bape. (Iretana,| Bristol |“ gng’ |Yorkshire.| “oyi00 | West’ | sostiena. | MCW.”
Harlow: moreland.
Cladacanthus paradoxus, Agass., . x = x = a
major, Davis, . x - — : s js a =
Physonemus armatus, M‘Coy, x - > Be = re os
a subteres, Agass., x - - = = = z 2
“9 attenuatus, Davis, x = - = = = a -
hamatus, Davis, x eX = — es e = ie

Chalazacanthus verrucosus, Davis, . x = = - = = = 2

Cladodus mirabilis, Agass., . x x ss x = x =

7 marginatus, Agass., . x Be - 2 a = x sf
) elongatus, Davis, . : x< - - we ee as as =
” striatus, Agass., x - = x x x x x
55 curvus, Davis, 4 = = Be es = es =
rs destructor, Davis, . 5 - - = oh = a sz
- acutus, Agass., . eee x - = = = Z es Es
” Milleri, Agass, . . = x - = = z x iS
os conicus, Agass., . - x - = Ps s x S
5 basilis, Agass , x - - x a = = se
3 Hornei, Davis, = —~ a x ae es me ae

mucronatus, Davis, - - = x = u = =

Carcharopsis Colei, Davis, x = = es Bi = des =

Pristicladodus dentatus, M‘Coy, 5 x - - x x B x =

” concinnus, Davis, . x“ Zo es ef se oe os

Goughi, M‘Coy, = x x = x ee

Glyphanodus tenuis, Davis, . = - x x ES = eS =
ORODONTIDA.

‘Orodus ramosus, Agass., x x SG x = 3 = ss

»  cinctus, Agass., x x x pa a a x Bs

»  porosus, M‘Coy, x pi eS s oe 2

»  compressus, M‘Coy, x = = = = ae sas as

3»  elongatus, Agass., x = - = = a a ae

>» augustus, Agass., x = - es es a a eS

»  catenatus, Agass., . x eS = ge = = =e a

*)  gibbus, Agass., x = S = 2 = = ae

»  sculptus, Davis, = - - a a zs ng

3 ornatus, Davis, : = = = = ee es a a

»,  Mmoniliformis, Davis, = = - = = a zs 2

»  Reedi, Davis, . = = = x eh es A a

3 tenuis: Davis, . ° : Pa = - = = = ae eS

subteres, Agass., — x x ED 2 & Ks as

Petrodus patelliformis, M‘Coy, = = = = x pe x =

Rhamphodus dispar, Davis, . x = = = a a &.

Lophodus levissimus, Agass., . x x x = & = x ss
a3 gibberulus, Agass., x x a - - = ee ass
ns mamumilaris, Agass., x se x = 2 es x =
e didymus, Agass., . x = x ee oe e x oe
3 reticulatus, Davis, 5 = = x & = se pa
a serratus, Davis, = ee s es an = as ce,
is bifurcatus, Davis, = = = a as ts es
96 levis, Davis, : ~ = = = = a a ze

sinuosus, Davis, . : = = es : = a = ae,

Diclitodus scitulus, Davis, . = = = x = ss = ie

COCHLIODONTID &.

Cochliodus contortus, Agass., x x x x aa x Ss

Streblodus oblongus, Agass., x = = = gs 2 =
s Colei, Agass., x oa = ee = as ae as

Egertoni, Agass., - | Hook point. = ee ae = a a as

Deltodus sublevis, Agass., i x a i a Re gS me =
os expansus, Agass., . : - = = = = ee oe as

a aliformis, Agass., - = = x x = x oe
Deltoptychius acutus, Agass., x x = x x = x s
gibberulus, Agass., x = Ee iS = ES a 2

Sandalodus Morrisii, Davis, . - x x = 2 = a =

Psephodus magnus, "Agass. ie 7 x = = x x x x x

Peecilodus Jonesii, Agass., “ x = = x = = x x
. obliquus, Agass., x Ee = = a x x He
By corrugatus, Davis, : a oS ee = x = = =
foveolatus, M‘Coy, . - - - = x a = =

 
''On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 547

TABLE—continued.

 

Salop
Oreton, York- Derby- Kendal, W.

and shire. shire.
Farlow.

Lowick,

West- | scotland.| N.W.
moreland.

Armagh

Name. (Ireland). Bristol.

 

 

Pecilodus gibbosus, Davis, . : ‘
Tomodus convexus, Agass., . :
Xystrodus striatus, Agass., . ° .
angustus, Agass., : °
Egertoni, Davis, .

‘5 pulchellus, Davis,
Helodus crassus, Davis,
tenuis, Davis, 5
»  Clavatus, Davis, . :
acutus, Davis, : .
Richmondiensis, Davis, .
triangularis, Davis,
expansus, Davis,
rudis, M‘Coy,
Pleurodus Woodi, Davis, . : ; = -

1

I

|

|
Pe ee!
Tiel age A

”
”

«tea @ geese
1

lexxxcaxxx ! xe 1
|
|
|
|
1
I
1

PSAMMODONTID &.
Psammodus rugosus, Agass., . » x x - x = x x x

COPODONTID.

~Copodus cornutus, Agass.,

furcatus, Agass., : f
‘; spatulatus, Agass., . : :
») minimus, Davis, .

Labodus prototypus, Agass.,

» planus, Agass., : :
Mesogomphus lingua, Agass., ‘ 6
Pleuragomphus auriculatus, Agass.,
Rhymodus transversus, Agass., .

‘ oblongus, Davis, 0
-Characodus angulatus, Agass.,
cuneatus, Agass.,
Pinacodus gonoplax, Agass.,
: 5 gelasimus, Agass.,
Dimylius Woodi, Agass., 5
Mylax batoides, Agass., 5 5 :
Mylacodus quadratus, Agass., 5
Re sesamini, Agass., s
Homalodus trapeziformis, Davis, ,
quadratus, Davis, °

|
|
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I
I
|
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PETALODONTID.

Petalodus Hastingsie, Owen, A
7 acuminatus, Agass., . :
5 rectus, Agass., . 5
os grandis, Davis, .
oe recurvus, Davis, . .
inequilateralis, Davis, .
Petalopsodus tripartitis, Davis,
Polyrhizodus radicans, Agass.,
3 Colei, Davis,
oi elongatus, Davis,
a sinuosus, Davis,
a attenuatus, Davis, . :
constrictus, Davis, 5 :
Chomatodus linearis, Agass. Ie ; .
acutus, ’Agass., « °

!
I
1
bose: tex
xox

I

|

|

|

1
x
x

”
Glossodus marginatus, M ‘Coy,

-Ctenopetalus serratus, Agass., . .
3 crenatus, Davis, . :
Harpacodus dentatus, ’Agass. Be ae ;
‘ clayatus, Davis, ,
Petalorhynchus psittacinus, ’Agass., :

INCERTA SEDIS.
Pristodus falcatus, Agass., » : ee - a = x x a = i

l

x

|

I

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xxx Kx |

Part

Mao x xe x Kx x ex ee x
|
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''548 Ox the Fossil Fishes of the Carboniferous Limestone Series of Great Britain.

TABLE—continued.

 

 

Babb, Kendal
Armagh ‘ Oreton, | York- | Derby. : W. Lowick,| Tort-
Nanie- (Ireland). ee, ae "| shire, shire. ee q{scotland.| N.W. "| worth.
arlow. 5
GANOIDEI.

Cheirodus pes-ranz, M‘Coy,

Colonodus longidens, M‘Coy,
Ceelacanthus sp? Agass.,

Oracanthus sp? Agass., :
Stichacanthus tortworthensis, Davis, 5
Phoderacanthus grandis, Davis, .

eel
eee eX

KL)
POINTE Vedio.
ride
Tea alate
eat alelond
eee fl

 

 

 

 

 

 

 

 

 

 

The preceding Table of Localities has been emp pica from the follow-
ing sources :—

Treland, principally Armagh, &c.—The Collection of Lord Enniskillen, and M. Agassiz’s “Poissons
Fossiles.”

Bristol—A gassiz ‘ Poissons Fossiles,” and the Bristol Museum Collection.

Oreton and Farlow—Messrs. Morris and Roberts, ‘Quarterly Journal, Geological Society,” Vol.
XVIII., p. 99, et seg.

Yorkshire, principally Leyburn, Richmond, Settle and Kettlewell—Collections of Dr. Reed at
the York Museum, and William Horne, Esq., of Leyburn.

Derbyshire—Prof. M‘Coy’s, “ British Paleozoic Fossils,” and Woodwardian Museum, Cambridge.
Westmoreland—Collection at the Museum of the Philosophical and Literary Society, Leeds.

Western Scotland—Messrs. Young and Armstrong’s lists in the “Trans. of the Geological Society,
Glasgow,” Vol. IfI., supt. p. 68, et seg., and Messrs. Armstrong, Young and Robertson’s
“Catalogue of the Western Scottish Fossils.” Glasgow, 1876.

Northumberland, Lowick, &c.,—Collection at the Woodwardian Museum, and Prof. M‘Coy’s “ British
Paleozoic Fossils.”
''5, DESCRIPTION CF PRAiie.

 

DESCRIPTION OF PLATE XLII.

 
''550

PLATE XLII.

Page
Fie. 1. Crenacantuus mMasor, Agassiz, 7 ° ° ° . . . 334
Probably posterior dorsal spine.
Limestone, Bristol, . > : e Ex. coll., Bristol Museum.
Fic. 2. OrENacANTHUS MAJOR, Agass., . 334

Probably anterior dorsal spine.

» 2. Section across the latter near the basal extremity.
a ao 5 5 near the point.
» 2d, Enlarged representation of surface markings.

Limestone, Armagh, ‘ : > Ex. coll. Enniskillen Collection.
Natural size.
''Trans.R.D.S.Vol. Las.

Plate XLII.

 

 

 

sa
aan
ween

 

 

 

 

 

 

JWDavis, direxit. /.U.Woodwara, del.

Forster & C%Lath Dublin.

 
'' 
''TRANS,

ROY. DUB. S0C., NS. VOL. TI.

 

DESCRIPTION OF PLATE XLIU.

 

40
''552

PLATE XLITI.

Fic. 1. CrENACANTHUS TENUISTRIATUS, Agass., . -

A large but imperfect specimen.
»» La. Section across the same.

Limestone, Bristol, : : E Lz. coll. Enniskillen Collection.

Fic. 2, CTENACANTHUS TENUISTRIATUS, Agass.,
» 2a. Section showing the posterior cavity.
» 26. Section nearer apex, cavity enclosed.

Limestone, Bristol, : ; ‘ : Lx. coll. Bristol Museum.

Fig, 3, CTENACANTHUS BREVIS, Agass., ; : .
», 3d Section near the base.

Limestone, Armagh, . . Fx. coll, Enniskillen Collection.

Natural size.

Page
339

335

337
'' 

 

 

Trans.R.DS.Vol.Lns. , , i : : : Plate XLUL.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

J. W.Davis, darext. WH Baily, del i Forster & C? Lith,Dubkn.

 

 
'' 
'' 

DESCRIPTION OF PLATE XLIV.

 

40 2
''554

PLATE XLIV,

Fic. 1. CrENACANTHUS HETEROGYRUS, A gass. MSS.,

» 1la.and 1 b. Sections of the same.

Limestone, Armagh, é : Ee coll. Enniskillen Collection.

1G8. 2, 3, CTENACANTHUS HETEROGYRUS, Agass. MSS.,

Mountain Limestone, Armagh, . Ez coll. Enniskillen Collection.

Fic. 4. CTENACANTHUS DENTICULATUS, M‘Coy, . : : : ;

» 4a. Portion of surface enlarged.

Shales of Monaduff, . Ex coll. Woodwardian Museum, Cambridge.

Fig. 5. CrenaACANTHUS LIMAFORMIS, Davis,

» © a, Section across the same.

Limestone, Bristol, : : £ez coll. Enniskillen Collection.

Fic. 6. CTENACANTHUS SALOPIENSIS, Davis,
6 a. and 6 b. Sections across the spine.
6 c. Portion of surface ornamentation enlarged.

99

)

Limestone, Oreton in Salop, Bristol, Ez coll. Enniskillen Collection.

Fig. 7. CTENACANTHUS DUBIUS, Davis, . : : ; Q

Limestone, Armagh, ; Lx coll. Enniskillen Collection.

Page
336

336

338

339

339

340
'' 

Plate XLIV.

Trans.R.D.S.Vol.[.n.s.

 

   

 

 

 

6b

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nasser
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Aa TAN SL

 

 

 

 

 

 

Forster & C° igeh,Dabtm.

J.W. Davis, divexit. WH Baily, del.

 

 
'' 
'' 

 

 
''556

PLATE XLV,

Fic. 1. Crenacantuus Lavis, Davis, ; :
», 1a. Section of the upper portion of the same.

Limestone, Armagh, A .

Fie. 2, CTENACANTHUS PUSTULATUS, Davis, ‘

Limestone, Armagh,

Fie. 3, CTENACANTHUS sULCATUS, Agassiz,
», 3a. Section of the upper part of the spine.

Limestone, Bristol,

Fic. 4. CTENACANTHUS PLICATUS, Agassiz,

» 4a. Enlarged representation of the surface SOAHON.

» 46and 4c. Sections across the spine.

Ex coll. Enniskillen Collection.

Ex coll. Enniskillen Collection.

Ex coll. Bristol Museum.

Limestone, Armagh, : . Ex coll. Geological Society’s Museum.

Fig. 5. Crenacantuus (OncuHus) rectus, Agassiz, MSS.,

Limestone, Armagb, : Ex coll. Geological Society’s Museum.

Fie. 6. Crenacantuus crenucatus, Agassiz, MSS.,
» 6a. Section across the same.

Limestone, Armagh, .  xceoll. Woodwardian Museum, Cambridge.

Fig. 7. ACONDYLACANTHUS coLzI, Davis, .
», «a. Transverse section.

Limestone, Armagh, ; :

Fie. 8. ACONDYLACANTHUS TENUISTRIATUS, Davis,
», 8a. Transverse section.
», 8b. Part of surface enlarged.

Limestone, Armagh, : ;

Ex coll. Enniskillen Collection.

. Hx coll. Enniskillen Collection.

Page
341

344

343.

342

345:

345

347

350
''Plate XLV.

LS,

I

SVol

D

R

x

Tran

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Forster & C°lith,Dubhn. '

WE Baily, del.

avis, direxit.

J.WD

 

 
'' 
'' 

DESCRIPTION OF PLAT XLVI.

 
''Fic.

Fia.

Fic.

99

”

558

PUATE XLVI.

1. ACONDYLACANTHUS COLEI, Davis,
1 a. Enlarged portion of surface.

Carboniferous Limestone, Armagh, .

. 2, ACONDYLACANTHUS JENKINSONI, M‘Coy,

2a. Enlarged portion of surface.
2 6. Transverse section of the spine, enlarged.

Ex coll. Karl of Enniskillen.

Carboniferous Limestone, Lowick, Northumberland.

Ex coll. Woodwardian Museum, Cambridge.

. 3. ACONDYLACANTHUS ATTENUATUS, Davis,

3 a. Transverse section of the spine.
3 6. Enlarged portion of surface.

Carboniferous Limestone, Armagh, 2 coll. Woodwardian Museum, Camb.

. 4, ACONDYLACANTHUS TUBERCULATUS, Davis,

4 qa. Enlarged portion of surface.

Limestone, Armagh,

. 5. ACONDYLACANTHUS DISTANS, M‘Coy,

5 a. Enlarged portion of surface.

Limestone, Armagh,

. 6. ACONDYLACANTHUS JuNcEUS, M‘Coy,

6a. Enlarged portion of surface.

Ee coll. Earl of Enniskillen.

. Hx coll. Enniskillen Collection,

Limestone, Derbyshire, - Ea coll, Woodwardian Museum, Cambridge.

. 7. ASTEROPTYCHIUS ORNATUS, Agass.,

7 a. Transverse section of the spine.

Limestone, Armagh, : °

8 ASTEROPTYCHIUS ORNATUS, Agass.,
8 a. Enlarged portion of surface.

Limestone, Armagh,

. 9, ASTFROPTYCHIUS ORNATUS, Agass., :
9 a. Transverse section of the upper part of ae spine.

9}. Enlarged portion of surface.

Carboniferous Limestone, Armagh,

10. CompsACANTHUS CARINATUS, Davis,
10 a. Transverse section of the spine.
10 6. Portion of surface magnified.

Limestone, Armagh,

. Ex coll. Enniskillen Collection.

. Ex coll. Enniskillen Collection.

Page

347

351

352

348

349

350

353

353

3538

354
'' 

 

 

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v et
= a
ay 5
oS
&
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By

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ro

 

 

 

 

 

 

  
'' 
'' 

DESCRIPTION OF PLATE XLVII.

 

TRANS, ROY. DUB. SOC., N.S., VOL. I.

4P
''Pia.

Fic.

Fia.

Fic.

Fic.

Fie.

Fia.

. 3. Posterior branch of CLADACANTHUS PARADOXUS, Agass.,

560

PLATE XLVII.

. 1. CLADACANTHUS PARADOXUS, Agass.,

1 a. Transverse section of the anterior branch of the spine.
1 &. Transverse section of the posterior branch of the spine.

Carboniferous Limestone, Armagh, . Ex. coll. Enniskillen Collection.

_ 2. Anterior branch of CLADACANTHUS PARADOXUS, Agass., with well preserved distal

termination, . :
2a. The same termination magnified.

Carboniferous Limestone, Armagh, . Ex. coll. Enniskillen Collection.

3 a. The same magnified.

Carboniferous Limestone, Armagh, . Ex. coll. Enniskillen Collection.

4, CLADACANTHUS PARADOXUS, Agass, Anterior termination,

Carboniferous Limestone, Armagh, . Ex. coll, Enniskillen Collection.

5, CLADACANTHUS PARADOXUS, Agass. Anterior termination,
5 a. Transverse section of same.

Carboniferous Limestone, Armagh, . Ex. coll. Enniskillen Collection.

6. CLADACANTHUS MaAgor, Davis. Anterior extremity of a large specimen,

matural size. : ‘
Carboniferous Limestone, Armagh, . Ex. coll. Enniskillen Collection.
7. CLADACANTHUS MAJOR, Davis. Posterior extremity, ; ae : :
Carboniferous Limestone, Armagh, . Ex. coll. Enniskillen Collection.

8. PHysoNEMuUS ARcUATUS, M‘Coy,
8 a. Transverse section of same.

Limestone, Armagh, 3 : Ex. coll. Enniskillen Collection.
9, PHYSONEMUS HAMATUS, Agass., ‘ : ‘ ;
Limestone, Armagh, é : Ex. coll, Enniskillen Collection.
10. PuysonemMus ATTENUATUS, Davis, ‘ 4 : : : é
Limestone, Armagh, : ; Ex. coll. Enniskillen Collection.

. 11. Puysonemus HAMATUS, Agass.,

lla. Transverse section of spine near the basal extremity.
11 6. Ditto, near the apex.
Carboniferous Limestone, Armagh, . Ex. coll. Enniskillen Collection.

. 12. PHysoNEMUS SUBTERES, Agass., . ‘

12 a. Magnified portion of surface.

Carboniferous Limestone, Armagh, Ez. coll. Geological Society of London.

Page
365

365

365

365

365

366

366

367

369

370

368
''Plate XLVI.

Trans.RD.S.Vol.1.ns.

 

 

pHEMT Ray,
i ratte

 

 

Forster & C°Lith,Dubhn.

 

 

 

 

J. W.Davis, dirent. WH Baily, del.
''ei

 
'' 

"DESCRIPTION OF PLATE, XLVI

 

Pp ¢§
''562

PLATE XLYVITLE.

Fic. 1. CosmacaNTHUS PRISCUS, Agass., . ; : : : : .
Longitudinal section along centre of a spine.
Mountain Limestone, Armagh, . Ex. coll. Geological Society of London.
Fic, 2. Cosmacayruus priscus, Agass. External aspect of figure 1, : : :
» .24a. Transverse section of the same.
Mountain Limestone, Armagh, . Ex coll. Geological Society of London.
Fic. 3. CosMACANTHUS MARGINALIS, Davis, : : . . : .
»,. 3a. Transverse section of the same, near base.
Mountain Limestone, Armagh, ; Ex coll. Enniskillen Collection.
Fig. 4. CosmacaNTHus CARINATUS, Davis, : ‘ : : °
Carboniferous Limestone, Armagh, . Ez coll, Enniskillen Collection.
Fic. 5. LisPACANTHUS RETROGRADUS, Davis, : : ; ; : :

9)

itive.

Figs.

HIG:

o)

Fic.

29

Fia,

2”

Fic.

2

Fic.

”

29

5 a. Transverse section of the same.

Limestone, Armagh, : : Ex coll. Enniskillen Collection.

6, LISPACANTHUS GRACGILIS, Davis, ;. : ; : : : cS

Mt. ele Kendal a. Ex coll, Geological Society of London.
estmorelanc. 2 ee

7-9, Homacanruus micropus, M‘Coy, : : . ae : ‘

8. HomacantHus mMicropus, M‘Coy, 6 : : : : :

(Probably from the second dorsal fin).
8 a. Transverse section across the same spine.

All from Mountain Limestone, Armagh, Ex coll. Enniskillen Collection.
10. DipriacaNntTuus sToKEsi!, M‘Coy, ; . : ‘ : :
10 a. Enlarged portion of surface.

Mt. Limestone, Armagh, Ex. coll, Woodwardian Museum, Cambridge.
11. GNATHACANTHUS TRIANGULARIS, Davis, .. : ; 5 : :

11 a. Portion of surface of same magnified.

Mountain Limestone, Armagh, : Ex. coll. Enniskillen Collection.

12, GNATHACANTHUS sTRIATUS, Davis, : A : ; 5 :
12 a. Transverse section across the same.

Mountain Limestone, Armagh, 3 Ex. coll. Enniskillen Collection.

13. CHALAZACANTHUS VERRUCOSUS, Davis, . ‘ : ; ; :
13 a. Transverse section across the same, midway towards the apex.
13 b. Ditto, across the basal portion.

Lower Carb. Limestone, Black Rock, Bristol, Ex. coll. Bristol Museum.

Page

358

358

356

359

359

361

361

360

363

364

371
'' 

Plate XLVIU.

Trans.R.D.S Vol. ns.

 

 

 

 

 

 

 

 

 

Forster & C? Lith,Dubhin.

J.WDavis, direnit. WH Baily, dd.
'' 
'' 

DESCRIPTION OF PLATE XLIX.

 
''Figs. 1-5. CLADODUS MIRABILIS,

2)

”?

Fia.

564

PLATE XLIX.

Agass., :

4 a, Side view of specimen represented by figure

4b. View of under-surf:ice of base of figure 4.
Carboniferous Limestone, Armagh, .

6, CLapopus conicus, Agass.,
Limestone, Bristol,

Fics. 7-9. CLADODUS MARGINATUS, Agass.,

29

Fics. 10, 11. CLapopus ELoneatus, Davis,

Fies, 12,

Fic.

Fia.

Fia.

Fic.

HG:

Fig.

Fic.

Fic.

Fic.

9

Fic.

Fic.

Fie.

Fic.

Fia.

7 a. Antero-posterior section of same.
Mountain Limestone, Armagh,

Mt. Limestone, Richmond and Settle,
13. CLADODUS STRIATUS, Agass., .
Mountain Limestone, Armagh,
14. CLapopus curvws, Davis,
Mountain Limestone, Armagh,

15. CLrapopus DEstTRUCTOR, Davis,

Mountain Limestone, Armagh,

16. CLADODUS MILLERT, Agassiz,

Mountain Limestone, Bristol,

17. CLapopus AcuTus, Agass., ;

Limestone, Loughgall, near Armagh,

18. CLADODUS BASALIS, Agass.,

Mountain Limestone, Armagh,

19. Cuapopus curtus, Davis,
Mt. fine. Richmend, Wot hie.
20. Cuapopus Hornet, Davis,

Carboniferous Limestone, Le

21. Cuapopus mucronaTvs, Davis,
Carboniferous Limestone, es

22. PristicLapopus DENTATUs, M‘Coy,

22 a. Longitudinal section of the same.

Carboniferous Limestone, Wensleydaie,
23. PRISTICLADODUS CONCINNUS, Davis,

Carboniferous Limestone, Wensleydale,
24, GLYPHANODUS TENUIS, Davis,
24 a. Longitudinal section of the same.

Carboniferous Limestone, Wensleydale,
25, GLYPHANODUS TENUIS, Davis,

Carb. Limestone, Wensleydale,
26. CARCHAROPSIS COLEI, Davis,

Mountain Limestone, Armagh,
27. PrisTIcLaDopus GouGHI, M‘Coy, :

Lower Carb. Schists, Kettlewell, Ex

4,
Ex coll. Enniskillen Collection.

Ex coll. Bristol Museum

Ez coll. Enniskillen Collection.

Ex coll. Reed Collection, York Mus.

Ex LE Enniskillen Oollesion
| Ex ae Heals Collection.
Bo aE Enniskillen Collection.

Ew colt. Bristol Gian:

Ex coll. Geological Society, London.

.

Ex coll. Geological Society, London.

Ex coll. Reed Collection, York Mus.

Ex coll. W. Horne, Esq.

Ez coll. William Horne, Esq.

Lx coll. William Horne, Esq.

Ex coll, William Horne, Esq.

. Ex coll, William Horne, Esq.

Ez coll. Reed Collection, York Museum.

coll. Woodwardian Museum, Camb.

.

Ex coll. Enniskillen Collection.

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374

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379

380
380

384

385

386

386
383

385
'' 

 

coer & C2 Lith Dubin

Plate XLIX.

For

 

 

Trans.R.D.S.Vol. Ins.
WDavis, direxit. E.C. Woodward del

 

 

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''DESCRIPTION OF PLATE }

 

 
''566

PLATE L.

Fic. 1. Oropus ramosus, Agass., . :
Three large teeth in natural position.

Mountain Limestone, Bristol,
Fic. 2. Oropvs rAmosus, Agass., .

Mountain Limestone, Armagh,

Fic. 3. Oropus Ramosus, Agass., . Q
Two teeth in natural position.
» 3a. Anterior view of same, showing base as

Mountain Limestone, Armagh,

Fic. 4. Ornopus RAMOSUS, Agass., . :

Mountain Limestone, :

Fic. 5. Oropus ramosus, Agass,
» 9a. Posterior view of the same.

Anterior view,

» 5. Vertical section of do.

Mountain Limestone Armagh,

Fics. 6,7. ORopus RAmosuS, Agass.,

Mountain Limestone, Oreton, Salop,

Fic. 8. Onopus cinctus, Agass., . :
Four teeth in satu.

Mountain Limestone, Bristol,

Fic. 9. Oropus crnctus, Agass., .
Mountain Limestone, Bristol,
Fig. 10. Oropus porosus, Agass., :
Three teeth in natural position,
Mountain Limestone, Armagh,

Fic. 11. Oropus comprREssus, Agass.,

, lla. The same magnified.

Mountain Limestone, Armagh,

Hx coll. Bristol Museum.

Ex coll. Bristol Museum.

well as crown.

: Ex coll. Enniskillen Collection.

Lx coll. Geological Society, London.

Ex coll. Bristol Museum.

Hz coll, Enniskillen Collection.

. Lx coll. Geological Society of London.

. £x coll. Geological Society of Ireland.

Page

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390

390

390

oo
SO
»
©

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392

393

394
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J WDavis, chirexit. E.C. Woodward. del

Forster & C° lath,Dublin.

 
'' 
'' 

DESCRIPTION OF PLATE LI.

 

TRANS. RGY. DUB. SOC., N.S., VOL, I.

4@
''568

PLATE LI.
Fies. 1, 2, 3. Ornopus ELONGATUS, A gass., : ; : : : ;
Mountain Limestone, Armagh, = Ez coll, Enniskillen Collection.
Fic. 4. Ornopus aveustus, Agass., : : ; :
Mountain Limestone, Armagh, . Ex coll. Geological Society, London.
Fic. 5. ORopuS caTENATUS, Agass., : A : A :
» 5a. The same magnified.
Mountain Limestone, Armagh, ; Ex coll. Enniskillen Collection.
Fics. 6, 7. Ornopus cippus, Agass., 3 ; : ; 5 . s
Mountain Limestone, Armagh, : Lx coll. Enniskillen Collection.
Fic. 8. Oropus scuLptTus, Agass., 5 : : : , ‘
» 8a. The same magnified.
Mountain Limestone, Bristol, : : Ex coll. Bristol Museum.
Fic. 9. Oropus ornatus, Davis, ; ‘ : : A ; .

9 a. Same, magnified.
Mountain Limestone, Richmond, Yorkshire, /x coll. Enniskillen Collection.

Figs. 10, 11, 12. Oropus moniuirormis, Davis, .

or.

Mountain Limestone, Armagh, : Ex coll. Siac Collection.

Fig. 13. Onopus REEDI, Davis, . ‘
13 a. Upper surface of same specimen.
Mt. Limestone, Settle, Yorkshire, Ha. coll. Reed Collection, York Museum.

Fig. 14. Oropus TENUuIS, Davis,

”)

Mountain. Limestone, Armagh, : Bx coll. Enniskillen Collection.
Fig. 15. Ornopus sUBTERES, Agass., : 4 : :
Mountain Limestone, Black Rock, Bristol, . Ez coll. Bristol Museum.

Fig. 16. Perroous PATELLIFoRMIS, M‘Coy,
» 16a. Upper surface of same; 16 0. Magnified view ca figure 16.
Mt. Limestone, Derbyshire, Eo. coll. Woodw ardian Museum, Cambridge.

Fic. 17. Ruampnopus pispaR, Davis, : : : : : A .
» 17a. Side view of longer lateral extension.
Mountain Limestone, Armagh, : Ex coll. Enniskillen Collection,

Fic. 18. Lopnopus tavisstmus, Agass.,
» 18a. Upper surface of another specimen.
» 186.,18¢. A series of teeth (diagrammatic).

Mountain Limestone, Armagh. : Ex coll, Enniskillen Collection.
Fic. 19. LopHopus GIBBERULUS, Agass., : : : : :
Mountain Limestone, Armagh, : iu coll. Enniskillen Coliection.
Fig. 20. LopHopus MAMMILARIS, Agass., : : : : : :
Mountain Limestone, Armagh, : Lx coll. Enniskillen Collection.
Figs. 21, 21 a. Lopnopus pipymus, Agass., : : : : : :
Mountain Limestone, Armagh, : Hz coll. Enniskillen Collection.
Fig. 22. LopHopus RETICULATUS, Davis, ; : : : :
Carb. Limestone, Wensley dale, Yorkshire, : Ex coll. Wm. Horne, Esq.

Fias. 23, 24. LopHopus seRRATUS, Davis,
Carboniferous Limestone, Wensleydale, Ee coll. Wn. Horne (Fig. 24) and
Reed Collection, York Museum.

Fig. 25. LopHopus BIFURCATUS, Davis,
25 a. Side view of the same specimen.
Carboniferous Limestone, Wensleydale, ; Ex coll. Wm. Horne, Esq.

Fic. 26. Lopnopus tevis, Davis,
Mt. Limestone, Richmond, Yorkshire, Hx coll, Reed Coll, York Museum.

Fig. 27. LopHopvs LEvis, Davis, : : ; ° ‘
A series of four teeth in natural position.
Mountain Limestone, Richmond, Yorkshire, Ex coll, Wm. Horne, Esq.
Fia. 28. Lopnopus sinuosus, Davis,
Mt. Limestone, Richmond, Yorkshire, Ex coll. Reed Coll., York Museum.

Fic. 29. Dicurropus scrtutvs, Davis, : : ; : : ‘ 7
29 a. The same specimen magnified.
Carb. Limestone, Wensleydale, Yorkshire, . Ex coll. Wm. Horne, Esq.

2?

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395

395

396

396

397

398

398

399

399

400

402

404

405

406

407

407

408

408

409

409

409

410
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oJ) WDavis, direxit. E.C. Woodward, del. Forster & C°Lath,Dubhn.
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''Fig.

Fia.

Fic.

Fic.

570

PLATE LII.

1. CocHLiopus conToRTus, Agass., .
1 a Anterior view of the same.
1 6. View of the under side.
Mountain Limestone, Clifton, Bristol, . zx coll, Earl of Enniskillen.

2, CocHLIODUS CoNTORTUS, Agass.,  . us : : : °

Mountain Limestone, Clifton, Bristol, Hx coll. Geological Society, London.

3. CocHLIODUS conToRTUS, Agass.,

Mountain Limestone, Bristol, é Lx coll. Enniskillen Collection.

. 4, Posterior tooth of Cocuiiopus contortus, Agass.,

4a. Section of the end of the tooth, highly curved.
4b. Under side of the same tooth showing the enrolment.

Mountain Limestone, Bristol. é Ex coll. Enniskillen Collection,

. 5, COCHLIODUS ConTORTUS, Agass., . : i : ; : .

5a. Small anterior tooth, showing the enrolment of the teeth.

Mountain Limestone, Bristol, : Ex coll. Enniskillen Collection.

6. CocHLiIopUs conToRTUS, Agass., : . :
Showing the teeth implanted on the cartilaginous mass of the jaw.

Mt. Limestone, Clifton, Bristol, Zz. coll. Woodwardian Museum, Cambridge.

Fics. 7, 8. DELTopus suBLavis, Agass.,

Fia.

99

Teeth of the right and left ramus of fi upper jaw.

Mountain Limestone, Armagh, . Lz coll. Enniskillen Collection.

9. DELropus suBLzVIs, Agass.,
Teeth of the lower jaw.

9a. Smaller tooth of lower jaw detached, side view.

Mountain Limestone, Armagh, ; £z coll. Enniskillen Collection.

Page
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421

421

421

421

428

428
''Trans.R.D.S. Vol. Ins. Plate Ll.

 

 

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'' 
'' 

DESCRIPTION OF PLATE LIIL

 
''572

PLATE LIII.

Fic. 1. StrEBLoDUS OBLOoNGUS, Agass., .
Teeth of the right and left ramus of the j jaw with a connecting palatal base.

Fic. 2. StREBLODUS OBLONGUS, Agass., . : : ;
Upper surface of posterior tooth,
Fic. 3. STREBLODUS OBLONGUS, Agass., . ; . : . . .

Under side of posterior tooth.

Fic. 4. StREBLODUS OBLONGUS, Agass.,
Tooth attached to a wide expansion of the bony j jaws or "palate.
All from Mountain Limestone, Armagh, Lx coll. a Collection.
Fiaes. 5,6. SrrEBLopUS CoLEI, Agass., .
Posterior teeth, right and left respectively.
Mountain Limestone, Armagh, : Lz coll. Enniskillen Collection.

Fiaes. 7, 8. STREBLODUS EGERTONI, Agass.,

Mt. Limestone, Hook Poa oe Wexford, Lx coll Enniskillen Collection.

Figs. 9,10. DEtropus Expansus, Davis,
Right and left teeth of the upper jaw.
Mountain Limestone, Armagh, : Fx coll, Enniskillen Collection.
Fig. 11. Dreitropus Expansus, Davis,
Tooth of the lower jaw.
Mountain Limestone, Armagh, : Ex coll. Enniskillen Collection.
Fie. 12. DEeLropus anirormis, M‘Coy, _ . : : : : : :
Upper Limestone, Derbyshire, Zz. coll. Woodwardian Museum, Cambridge.
Figs. 13, 14. DELroprycuius acutus, Agass.,
Right and left teeth of the lower jaw.
» 14a. Posterior surface of figure 14, enrolled over the jaw.

Mountain Limestone, Ar magh, : Lx coll. Enniskillen Collection.

Fic. 15. DeLttoprycuius acutus, Agass., : : 2 : ;
A large example of tooth from the upper jaw.

Fic. 16. Dettroprycuius acutus, Agass., : : : ; : _

Under side of figure 15.

Fic. 17. DELToPTYcHIUS AcuTUS, Agass., .
A smaller example from the opposite ramus of a , jaw to ‘the one , represented in
figure 15.
Carboniferous Limestone, Armagh, Ex coll. Enniskillen Collection.

Fias. 18, 19. DELTOPTYCHIUS GIBBERULUS, AGASS.,
Teeth of the lower and upper jaws respectively.
Carboniferous Limestone, Bristol and Hook point, Co. Wexford.
Lx coll. Enniskillen Collection.

Figs. 20, 21, 23. Pacitopus sonesi1, Agass., : : : ; c
Posterior teeth.
Carboniferous Limestone, Armagh, Ez coll. Enniskillen Collection.
Fig. 22. PaciLopus JoNESII, j : : : ; :
Anterior tooth.
Carboniferous Limestone, Armagh, Hx coll. Enniskillen Collection.
Fic, 24. Pacitopus oBLiguus, Agass., . : : : ‘ : :
Posterior tooth.
Carboniferous Limestone, Armagh, Fe coll. Enniskillen Collection.
Fig. 25. Pacitopus corrucatus, Davis, 5 : : “
Carboniferous Limestone, Wensleydale, Hx coll. William Horne, Esq.
Fic. 26. Pacttopus FovEoLatus, M‘Coy, : : : : : :
Carb. Limestone, Derbyshire, Zz. coll. Woodwardian Museuin, Cambridge.
Fic. 27. Pacriopus caipposus, Davis, : : 5 : ; : :

», 27a. Posterior surface, showing the enrolment over the jaw.
Mountain Limestone, Armagh, : Ex coll. Enniskillen Collection.

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433

433:

433

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443

445
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Plate LIM.

 

 

 

 

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''574

PLATE LIV.

Fies. 1, 2. SANDALODUS MoRRISII, Davis,
Teeth of left and right rami of the ioe jaw.

Mountain Limestone, Bristol, - : Ex coll. Bristol Museum.

Figs. 3, 4. SANDALODUS MoRRISII, Davis, : : : :
Teeth of left and right rami of the upper jaw.
oo Transverse section of figure 3.
» 36, Longitudinal section of figure 3.
4a. Under surface of figure 4.

Mountain Limestone, Bristol, . £x coll. Dr. Grenfell, Bristol.

9?

Fras. 5, 6. SANDALODUS MoRRISII, Davis, : . : : P
Large examples of teeth of lower gia upper jaws.

Mountain Limestone, Oreton, Salop, fx coll. Enniskillen Collection.

Fies. 7-10, XYSTRODUS STRIATUS, Agass., . . . : . ‘

Mountain Limestone, Armagh, : Ex coll. Enniskillen Collection.

Page
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437°

437

448
''Trans.R.D.S Vol.\.ns Plate Ly:

 

 

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DESCRIPTIO

 
''576

PLATE LV.
Page
Fics. 1-14. Psepnopus macnus, Agass., : : : : A 439
Fias. 1, 2, 3. A set of three teeth which probably occupied the ramus of one jaw.
Figs. 1a, 2a, 3a. The same set of teeth, showing under-surface hollowed out for attachment
to the jaw.
Fic. 4. Three helodoid teeth of PsrpHoDUS MAGNUS in natural position relative to each other.
Fic. 5. Under-surface of larger specimen similar to figure 3.
Fic. 6. Two attached teeth showing crenulated edges.
Fias. 7, 8, 12. Several teeth of PsEPHODUS MAGNUS.
Fig. 9. Three teeth in natural relative position, attached.
Fic. 10. Side view of tooth, probably from the upper jaw, highly convoluted with crenu-
lated edge.
Fic. 11. Side view of small tooth.
Fics. 13, 14. Two large posterior teeth, much worn by attrition.
All from Mountain Limestone, Armagh, x coll. Enniskillen Collection.
Figs. 15-18. Tomopus convexus, Agass., 4 ; : : : : 446
Fic. 15 a. Transverse section of tooth represented by figure 15.
Fias. 16, 17. Teeth probably occupying opposite rami of the jaw.
Fic. 16 a. Side view of figure 16, showing its enrolled form.
Mountain Limestone, Bristol, Hx coll. Fig. 16, Bristol Museum. Figs. 15
and 17, Enniskillen Collection.
Fic. 18. Tomopus convexus, Agass.
Smaller elongated teeth.
Fig. 18 a. Longitudinal section of same tooth.
Mountain Limestone, Bristol, : : Hz coll. Bristol Museum,
Fics. 19, 20,21. Xystropus auausrus, Agass., : : : y : 449
Mountain Limestone, Armagh, : Ez coll. Enniskillen Collection.
Fias. 22, 23. XYSTRODUS EGERTONI, Davis, . : . 3 : é 450
Fic. 23 a. Lateral aspect of same specimen, figure 23.
Mountain Limestone, Bristol, : Ez coll. Enniskillen Collection,
Fic. 24. Xysrropus PULCHELLS, Davis, : : : : 3 5 450

Fic. 24a. The same magnified.
Mt. Limestone, Wensleydale, Yorkshire, Hx coll. Reed Collection, York.
'' 

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'' 

DESCRIPTION OF PLATE LVI.

 

4R2
''578

PLATE LVi.

Page

Fics, 1-7. Psammopus rucosus, Agass., . é ‘ : 3 : 459

Fic. 1. Upper surface of a large example of the commonest form of the teeth.
,, la. Lateral view of the base of same specimen.

» 10. Anterior extremity of the same, showing thickness of base and crown.

Fics, 2, 3, 5. Examples of ordinary form of the teeth. The upturned left lateral extremity
of figure 2, may be noted. The hollow has probably been produced by the
grinding of the opposing teeth. The hump of figure 5, is also peculiar.

Fias. 4, 6. Triangular teeth occupying the positions indicated in the woodcut on page 462,
at the anterior extremity of the palate.

Mountain Limestone, Armagh, . . Ex coll. Bristol Museum.

Fic. 7. Triangular tooth, similar to those above.

Mountain Limestone, Armagh, . Lz coll, Enniskillen Collection.
''Trans .RDS.VoLLns. Plate [V1].

 

 

 

 

 

 

 

 

 

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''580

PEATE LViL

Page

Fies. 1-7. Psammopus KuGcosus, Agass., ; 3 ; ; i : 459

Fig. 1. A group of three or four teeth disturbed and somewhat fragmentary.

Mountain Limestone, Bristol, : : Ex. coll. Bristol Museum;
Fic. 2. A thick specimen of lateral row of teeth.

Fic. 3. Triangular tooth probably occupying the anterior extremity of line of lateral teeth
(see woodcut on page 462).

» oa. Posterior extremity of same in section.

Fias.4, 5. Examples of ordinary form, much worn.

» 5a. Lateral elevation of figure 5, base and crown very thin.
Fig. 6. A large example peculiarly long in proportion to the breadth.

Fig. 7. Upper surface of a lateral specimen.
» 7a. Under surface of the same tooth.

Specimens represented by figures 2-7 , from Mountain Limestone of Armagh,
Ex coll, Fnniskillen Collection.
'' 

Trans.R.D.S.Vol.Lns. Plate LVI.
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''582
PLATE LVIII.

Fics. 1-5. Copopus cornutus, Agass. : ; ;

» 1. Upper surface. 1a. Under surface. 1 0. Lateral surface.

,» 3, 4. Small posterior teeth (formerly C. lunulatus, Agass.)

,, 4a. Posterior surface of figure 4, showing relative proportions of crown and base.
Fies, 2,5. The large and small forms attached in natural position.

Carboniferous Limestone, Armagh, . . Ex coll. Enniskillen Collection.
Fic. 6. Copopus Frurcatus, Agass., es : : : :
Carboniferous Limestone, Armagh, . . Ex coll. Enniskillen Collection.

Fic. 7. Copopus sPaATULATUS, Agass.,
With small posterior tooth attached.
Carboniferous Limestone, Armagh, . . Ex coll, Enniskillen Collection.

Fic. 8. Copopus minimus, Davis, . : : > : :
Carb. Limestone, Richmond, Yorkshire, . Ex coll. Enniskillen Collection.

Figs. 9-11. Lazopus prorotypus, Agass., :
» 9. Upper surface. Fig. 10. Under surface of base.

el, 5 Hig, 11a. ,; ; ou same,
5 11D. Posterior elevation, showing relative extent of base and crown.
Carboniferous Ei cou6, Armagh, . . Ex coll. Enniskillen Collection.
Fics. 12-14. Lazopus pLanus, Agass., : : : : :
Carboniferous Limestone, ak, : . Ex coll. Enniskillen Coliection.

Fig. 15. PLEUROGOMPHUS AURICULATUS, Agass., . : : :
Upper surface. Fig. 15 a. Under surface. Fig. 15 6. Anterior elevation.

Carboniferous Limestone, Armagh, . ° Ex coll, Enniskillen Collection.
Fic. 16. Mesocompuus Lincua, Agass., : : : é : :
Carboniferous Limestone, Armagh, . . Ex coll. Enniskillen Collection.
Fic. 17. RHyMODUS TRANSVERSUS, Agass., . : : : : :
Carboniferous Limestone, Armagh, . . Ex coll. Enniskillen Collection.

Fic. 18. Ruymopus optoneus, Davis,
, 18a. Under surface of same specimen.

Carboniferous Limestone, Armagh, . . Lx coll. Enniskillen Collection.
Fics. 19, 20, CHARACODUS ANGULATUS, Agass., : : : : :
Carboniferous Limestone, Armagh, : . Ex coll. Enniskillen Collection.
Fic. 21. CHARACODUS CUNEATUS, Agass., : : 3 : : :
Carboniferous Limestone, Armagh, . . Lx coll. Enniskillen Collection.

Fic. 22. Prxacopus Gonopnax, Agass.,
Pair of teeth attached i in natural position.

Carboniferous Limestone, Armagh, . . Ex coll. Enniskillen Collection.
Fig. 23. PinAcopus GELASIMuS, Agass., : s : : : :
Carboniferous Limestone, Armagh, . . Ex coll. Enniskillen Collection.

Fic. 24. DimyLevus woop, Agass.,
» 24a. Side view of the same specimen.

Carboniferous Limestone, Armagh, . . Ex coll. Enniskillen Collection.
Fics. 25, 26. Myzax BaTorpEs, Agass., : : : : : d
Carboniferous Limestone, Armagh, . . Ex coll. Enniskillen Collection.
Fics. 27, 28. Mytacopus quapratus, Agass., : ; : : c
Carboniferous Limestone, Armagh, . . Lx coll. Enniskillen Collection.
Fic. 29. MyLacoDus SESAMINI, Agass., : : : : ; :
Carboniferous Limestone, Armagh, . . Bx coll, Enniskillen Collection.
Fic. 30. HomMALopUS TRAPEZIFORMIS, Davis, : : : i
Carboniferous Limestone, Armagh, . . Ex coll. Enniskillen Collection.

Fic. 31. Homatopus quapRAtus, Davis,
Upper surface. Fig. 31 a. Under or basal surface.
31 0. Lateral surface.
Carboniferous Limestone, Armagh, . . Ex coll, Enniskillen Collection.

Page

464

468
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'' 

DESCRIPTION OF PLATE LIX.

 

TRANS, ROY, DUB. SOC., N.S, VOL, I.
''584

PLATE LIX.

Page

Fias. 1-2. Heropus crassus Davis, 453

» Ll. Profile of posterior aspect of medium-sized tooth.

‘ : a. View of the upper surface of crown from above.

» 2. Profile of anterior aspect of tooth.

5, 2a. Lateral elevation of the same tooth,
Carboniferous Limestone, Armagh, . Ez coll. Enniskillen Collection.

Fics. 3, 4. Hetopus TEenu18s, Davis, : . : 2 5 : rH 454

3. Posterior aspect of the tooth.

4, Anterior aspect of tooth imperfect on left extremity.

2?

9
4 a. Lateral elevation of same tooth.

Carboniferous Limestone, Armagh, . . Ex coll. Enniskillen Collection.
Figs. 5, 6. HeLopus ciavatus, Davis, . : é : ; * f 455
5. View of the upper surface of crown from above.

9?

6. Front view of another tooth.

6 a. Side view of same tooth.
Carboniferous Limestone, Armagh, . . Ex coll. Enniskillen Collection.

Fie. 7. HeLopus acutus, Davis, . : ; : ‘ : 4 : 455

7 a. Lateral elevation of same specimen.
Carboniferous Limestone, Armagh, . . Ex coll. Enniskillen Collection.

Fic. 8. HELODUS RICHMONDIENSIS, Davis, . : : : ; : ; 456
Anterior aspect.

8 a. Side view of the same tooth.
Carb. Limestone, Richmond, Yorkshire, . £x coll. Enniskillen Collection.

Fic. 9 Hetopus tRiancuLanis, Davis, . : é ; : j 456
Anterior or front view of the tooth.

9 a. Side view of the same tooth.
9 b. Posterior or back view of the same tooth.

Carboniferous Limestone, Armagh, . . Ex coll. Enniskillen Collection.
Fic. 10. HeLopus expansus, Davis, : ; ; ‘ ‘ : : 457
» 10a. Side view of the same specimen.
Carboniferous Limestone, Armagh, . . Ex coll. Enniskillen Collection.
Fic. 11. Hetopus rupis, M‘Coy, . : : : “ : : 457
» lla. View of the crown surface from above.
Carboniferous Limestone, Ex coll. Museum Geological Society, London.
Fics. 12-15. PLevropus woont, Davis, . - : ; ‘ 458

Carboniferous Limestone, oa Yorkshire,
Ex coll. Wm. Horne, Esq., Leyburn ; Reed Collection, York Museum.

Fics. 16-21. PETALODUS HASTINGSIZ, Owen, ‘ ; ; : ‘ 493
16, 19. Front views of average-sized specimens.

16 a. Longitudinal section of same tooth.

17. Posterior concave surface of another example.

18, 20, 21. Distorted specimens, probably from the posterior extremity of the jaw.
Mountain Limestone, Armagh, : . Ex coll, Enniskillen Collection.

Figs. 22, 23, PETALODUS ACUMINATUS, Agass. : : : ‘ : 3 494

22. Very large specimen—front view—base having the appearance of being divided
like Polyrhizodus.
Carboniferous Limestone, Richmond, Yorkshire,
Ex coll. Reed Collection, York Museum.

Fic. 24. PETALODUS ACUMINATUS, Agass., . ! . : : : 494
Carboniferous Te tectone Bicimond, . Ex coll. Enniskillen Collection.

2?
'' 

Frans. BUD S Vel. Lis. Plate LIX.

 

 

 

 

nee

 

 

 

oJ WDavis, direst, E.C. Woodward, del Forster & C? Lach,Dabhn.
'' 
''7

 

 
''586

PLATE LX.
Fic. 1. Peranopus Granvis, Davis, : : : é : : :
Posterior aspect of a large tooth, natural size.
Carboniferous Limestone, Armagh, Ex coll. Enniskillen Collection.
Fic. 2. Peranopus recurvus, Davis, : 4 : : : es
Mountain Limestone, Bristol, . : Ex coll. Enniskillen Collection.
Fias. 3, 4. PETALODUS INEQUILATERALIS, Davis, . 4 : d : A

,» 3. Anterior view of an average-sized specimen.
» 4. Posterior view of another example.

Mt. Limestone, Wensleydale, Yorkshire, Ex coll. Enniskillen Collection.

Fic. 5. Petatopus rectus, Agass., : : “ ‘ :
Carboniferous Limestone, Lowick.

Fic. 6. PETALOPSODUS TRIPARTITIS, Davis, ‘ : ; : dl :
,, 64a. Transverse section of figure 6.

Carb. Limestone, Wensleydale, Yorkshire, Ex coll. Wm. Horne, Esq.

Figs. 7, 8. PoLyRHIZODUS RADICANS, Agass., ‘ ‘ : : : :

» 7. Anterior surface of a large specimen.
, 8. Posterior or concave surface of another specimen.

Mountain Limestone, Armagh, ; Ez coll. Enniskillen Collection.
Figs. 9, 10. Potyruizopus couet, Davis, . : : . : : ‘

, 9. Convex front surface of a large specimen.
,, 10. Concave posterior surface of another specimen.

Mountain Limestone, Armagh, : Ex coll. Enniskillen Collection.
Fies. 11, 12, 13. Potyruizopus stnvosus, Davis, : es :
, 11. Anterior face of a large example.

, 12. A smaller example with lateral prolongations of the crown surface.

,, 13. Small specimen, probably immature, with crown, small and imperfectly developed.

Mountain Limestone, Armagh, ‘ Ex coll. Enniskiilen Collection.

Fic. 14. Potyruizopus atrenvuatus, Davis, : c : :
Anterior face of medium-sized example.

Mountain Limestone, Armagh, : Ex coll. Enniskillen Collection.
Fic. 15. Potyruizopus constrictus, Davis, : ‘ , : : : :
Mountain Limestone, Armagh, : Ex coll. Enniskillen Collection.
Fig. 16. Potyruizopus ELONGATUS, Davis, : : a : : z

Convex anterior surface.
,, 16a. Concave posterior surface.

» 16. Longitudinal section of tooth.

Mountain Limestone, Armagh, : Ez coll. Enniskillen Collection.

Page
496

497

497

500

506

503
''Plate LX.

Trans. R.D.S.Vol.1.n.s.

 

 

 

 

 

 

 

 

cer & C? Lath, Dublin

orst

iat

 

avl

a

VD

  

 

 
'' 
'' 

 

 
''588

PLATE LXI.

Page
Fic. 1. CHomatopus LINEARIS, Agass., 5 : : : : - ee
View of surface of crown from above.
» 1a. Longitudinal section of same tooth.
Mountain Limestone, Armagh, : Ex coll. Enniskillen Collection.
Fic. 2. CHomatopus acutus, Davis, ; : ‘ 3 : ‘ ‘ 509
Front view of an example imperfect at one end.
» 2a. Longitudinal section of the same tooth.
Mountain Limestone, Armagh, : Ex coll. Enniskillen Collection.
Fics. 3-5. Giossopus marcinatus, M‘Coy, : ; : : ‘ : 510
» 9 Anterior aspect of an example of ordinary size.
., 3a. Longitudinal section of the same tooth.
» 30, Posterior surface of same.
» 4. Diagrammatic section, exhibiting the arrangement in the mouth.
» 0. Example, with a pointed apex.
» 0a. Side view of the same specimen.
Mountain Limestone, Armagh, : Fx coll. Enniskillen Collection.
Fics. 6-8. CreNoOPETALUS SERRATUS, Agass., ; ; “ : 512
» 6a. Longitudinal section of tooth iaoied by aoe 6.
», 8. Posterior concave face of another specimen.
Mountain Limestone, Armagh, : Hx coll. Enniskillen Collection.
Fic. 9. CTENOPETALUS CRENATUS, Davis, . : : : : : : bls
» 9a. Longitudinal section of same tooth.
» 9. Posterior surface of figure 9.
Mt. Limestone, Wensleydale, Yorkshire. Lx coll. Wm. Horne, Esq.
Fig. 10. Harpacopus DENTATUS, Agass., . : ; a : : : 514
Mountain Limestone, Armagh, : Lx coll, Enniskillen Collection.
Fic. 11. Harpacopus ciavatus, Davis, ; é : ; j : 515
Mountain Limestone, Armagh, : Kz coll, Enniskillen Collection.
Figs. 12-16. PETALORHYNCHUS PSITTACINUS, Agass., : : 3 : : 516
,, 12. Anterior surface of a broad and short example.
,, 13. Anterior surface of a much narrower and longer example.
», 14. View of posterior spatulate surface of a large tooth.
,, 15. Three teeth in natural relative position, horizontally.
,, 16. Five teeth in natural relative position, vertically.
», 16a. Diagrammatic section through the same, showing how successive teeth become
anchylosed to those older and smaller.
Mountain Limestone, Armagh, : Ex coll. Enniskillen Collection.
Figs. 17-22. Pristopus ratcatus, Agass., : - : ; : : pug

17. View of the interior surface of the upper jaw.
19. View of the exterior surface of the upper jaw, with the pointed apex of the
lower one projecting in the interior.
22. Lateral view of the right side of the upper jaw.
21. View of the interior surface of the lower jaw.
18. View of the exterior surface of the lower jaw.
20. View of the under surface of the lower jaw.
Mountain Limestone, Wensleydale and Richmond, Yorkshire.
Lx coll, Wm. Horne, Esq., and Reed Collection, York Museum.
''- frans.R.D.S.Vol.lmns. Plate LXL

 

 

 

 

 

 

 

 

 

‘el WDavis, direxit. E.C. Woodward, del Forster & C? Lith, Dublin.

 
'' 
'' 

 

 
''590

PLATE LXIT.

Page
Figs, 1-15. ORACANTHUS MILLERI, Agass, : : : ‘i : : 52h
», 1. Central dorsal bone of cranium.
», 2. Upper portion of similar plate represented by figure 1.
3. Jugular plate? or sphenoid bone.
» 4. Upper jaw?
5. Head bone.
6. Cheek plate or operculwn ?
» v. Lower jaw.
» 8, 10, 11. Bones forming part of the dermal covering of the head.
» 9. Head bone of Oracanthus (Platycanthus isosceles of M‘Coy).
, 12. Jugular plate?
», 13. A peculiar squarely formed bone.
» 14, 15. Small head bones. (Coccosteus and Asterolepis of M‘Coy.)

Mountain Limestone, Armagh, : Ex coll. Enniskillen Collection.
''Trans.R.DS.Vol.l ns.

Plate LXIL.

 

 

 

 

pavarseniireercossealsso™

oe

aeegnt ePROC RR trees PT

 

 

15.

 

J.W Davis, direxit. H Sykes, del.

 

 

 

 

Forster & C°? Lath, Dubin
'' 
'' 

DESCRIPTION OF PLATE LXIII.

 

TRANS, ROY, DUB, SOC,, N.S., VOL I,

4 T
''592

PLATE LXIII.

Page
Fies. 1-4. ORACANTHUS MILLERI, Agass., — : : : : : 525
» lL. Upper or anterior surface of dermal plate.
», la. Lateral view of same specimen.
» 10. Section near the apical extremity, showing the thickness of the bony part and
large internal cavity.
5, 2. Sinistral example of specimen similar to figure 1.
3 3. Dextral example of a similar specimen.
Mountain Limestone, Armagh, ‘ Ex coll. Enniskillen Collection.
,, 4. Peculiarly shaped bone, forming some portion of the external covering of the fish,
Mountain Limestone, Bristol, : Ex coll, Enniskillen Collection.
Fic. 5. CHEIRODUS PES-RANA M ‘Coy, : 523
,, Da. A magnified view of the same specimen.
Mountain Limestone, Derbyshire, Hx coll. Woodwardian Museum, Cambrid ge.
Fig. 6. Cotonopus LoneipEeus, M‘Coy, .. : : : : : 523.
Mountain Limestone, Armagh, Zz coll. Museum of Geol. Society, London,
Fies. 7-12. External covering of Ca@Lacantuus, Agass., . : : : : 524

Fic. 7 Under-surface of the operculum.
,», 8. Upper-surface of the operculum.
» 9. Dermal covering from head.
,, 10. Jugular plate.
», Ll. Head plate.

», 12. Scale.
Mountain Limestone, Armagh, ; Ex: coll. Enniskillen Collection.
''Trans.R.DS.Vol.Lns. Plate LXUL

 

 

 

 

 

 

 

 

 

 

J.W.Dawis, direxit. H. Sykes, dei ith, Dubh:
ykes, dei. Forster & C° Lith, Dabhn
'' 
'' 

DESCRIPTION OF PLATE LXIV.

 

T 2
''594

PLATE LXIV.
Page
Fie. 1. ORacaNTHUS MILLERI, Agass., ; : : - 525
Posterior view of bony dermal covering, with wide and open basal cavity.

», 1a. Anterior aspect of the same specimen.

» 16. Transverse section of the same.

», 1c. Longitudinal section of the same specimen.

Mountain Limestone, Bristol, A Lz coll. Enniskillen Collection.

Fic. 2. ORACANTHUS MILLERI, Agass., . 3 : : ‘ : 7 a2>

Very large specimen ; imperfect, very thin, and flattened.
Mountain Limestone, locality not known.

Lx coll. Museum of the Geological Society, London.
''Plate LXIV

Trans.R. DS Vol. Ins.

 

 

 

 

 

 

 

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orster & C° Lith, Dublin.

Fe

 

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J.W.D:

 

 
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'' 
''596

PLATE LXV.

Fic. 1. PHoDERACANTHUS GRANDIS, Davis,
» la. Section of the spine near the apical extremity.

Mt. Limestone, Bristol, . Lz coll. Earl of Ducie, Tortworth Court.

Fic. 2, STIcHACANTHUS TORTWORTHENSIS, Davis, .

», 2a. Section of the spine near the apical extremity.

Mt. Limestone, Tortworth, . Ez coll. Earl of Ducie, Tortworth Court.

Fies.3, 4. ORACANTHUS MILLERI, Agass.,

Two peculiar bones apparently pertaining to Oracanthus.

» .%& External surface with similar ornament to the dermal coverings of Oracanthus.

» 3a. Section of spatulate portion of the same.

» 4. Internal aspect of another specimen.

» 4a. Section of the same.

Mountain Limestone, Armagh, : Lx coll. Enniskillen Collection.

Page
534

532

525
''Trans. R D.S.Vol.Lns.

Plate LXV.

 

 

 

 

on
A

 

 

 

 

JW Davis, direxit. H Syies, del.

Forster & C* Lith, Dobhin.

 

 
'' 
''ee ee ee N

Pe OD Rw Ne Noe ee

 

Rb b> > bh

- ©. angulatus, 462, 474, 475, 476.

 

597

6. INDEX TO GENERA AND SPECIES.

 

** The genera described in the Memoir are printed in CAPITALS, the species in Roman, others and the
synonyms in Jtaliec.

AconDYLACANTHUS, 333, 346, 360.
. equicostatus, 347, 348, 349.
. attenuatus, 352.

. colei, 347, 352.

. distans, 349, 350.

. gracilis, 347, 352.

. jenkinsoni, 351, 352.

. Junceus, 350.

. occidentalis, 352.

A. tenuistriatus, 350.

A. tuberculatus, 348.

Acrodius, 411,.412.

A. larva, 490.

Agussizodus, 332, 387, 389, 390, 403, 420.
Antacanthus, 533.

A. insignis, 534,

Antliodus, 484, 485, 508.

A. mucronatus, 484.

Armagh, Mountain Limestone at, 537.
Aspidodus, 438, 439.

Asterolepis, 361, 525, 526, 527.

A. verrucosa, 525, 526, 529.
ASTEROPTYCHIUS, 353.

A. ornatus, 353, 354.

A. semiornatus, 353, 354.

Batoidei, 329.
Bristol, Mountain Limestone at, 540.

Carcharodon, 382.

CarcHARopsIS, 381,

C. colei, 383.

C. dentatus, 383.

C. prototypus, 381, 382, 383.

C. worthent, 382, 383.

Ceratodus, 411, 412, 417, 418, 419, 523.
Cestracion, 403, 411, 412, 413, 418, 419, 420.
Cestraciontide, 415.

Cestracionts, 331, 332, 333, 386, 388, 389, 411,
417, 483, 490.
CHALAZACANTHUS, 370.
C. verrucosus, 371.
CHaracopus, 474.

C. aureatus, 474.

OC. cuneatus, 475, 476.

CuEtRopus, 522.

C. pes-rane, 523.

Chimere, 339, 359.

Cuomatopus, 415, 451, 454, 484, 485, 495, 498,
507, 518.

C. acuminatus, 483, 507, 516.

 

C. aeatus, 509.

C. cinctus, 453, 454, 507.

C. denticulatus, 507.

C. linearis, 411, 484, 457, 508, 509.

C: obliques, 507.

C. venustus, 402.

Chondropterygit, 328.

CLADACANTHUS, 364.

C. major, 366.

C. paradoxus, 365, 366, 367.

Cuapopus, 331, 333, 347, 372, 382, 383, 386, 438.

. acutus, 377, 378.

. alternatus, 374, 375.

. basalis, 379.

, conicus, 378.

. curtus, 379.

CurvUSs, 3105-571.

destructor, 376.

. elegans, 380.

elongatus, 374, 380.

. grandis, 374.

. hornei, 380.

. levis, 373, 374.

. marginatus, 373, 374.

. milleri, 378, 379.

. Inirabilis; 372, 373, 301, 318, sie, ou:

. taucronatus, 380.

. springert, 385.

. Striatus, 374, 375, 378, 380.

. succinctus, 375.

. tenwistriatus, 347.

. wachsmuthi, 385, 386.

Climaxodus, 488, 492.

C. lingueeformis, 491.

Coccosteus, 525, 527.

C. carbonarius, 525, 526, 529.

Cochliodont, 413, 414, 419, 420, 422, 434, 446, 449,

CocHLIODONTIDA, 331, 332, 410.

Cocutiopus, 331, 410, 411, 412, 413, 415, 416,
417, 418, 420, 423, 425, 432, 433, 436, 437,
438, 447, 451, 452, 453.

. acutus, 413, 414, 432, 433, 452.

. compactus, 433, 434,

. contortus, 411, 413, 414, 421, 422, 423, 447,

. convexus, 546.

. magnus, 413, 414, 439, 440, 453.

oblongus, 413, 414, 422, 424.

. striatus, 413, 414, 448.

CasLAcANTHUvs, 524.

Cotonopus, 523.

C. longidens, 523.

CompsacantTuus, 454, 455.

DOO 2220222266696

QOS OSeray a
''598

C. carinatus, 454.

Conodonts, 520.

CopoponTip&, 331, 332, 462, 464.

Coponus, 331, 464,

C. cornutus, 464, 465, 466, 467, 468, 471, 477,

C. furcatus, 466, 467.

C. lunulatus, 464, 465, 477.

C. minimus, 467, 468.

C. spatulatus, 467. ~

Cosmacantuus, 355.

C. carbonarius, 356, 357.

C. carinatus, 356,

C. malcolmsoni, 355, 356, 357.

C. marginalis, 356.

C. priscus, 358.

CTENACANTHUS, 331, 332, 347, 348, 349, 350, 359,
369, 438, 527, 533.

: brevis, 337.

: burlingtonensis, 333.

. crenatus, 340, 345.

. crenulatus, 345.

. denticulatus, 338, 339, 340.

. distans, 347, 349.

. dubius, 340.

. gracllimus, 333, 347.

gradocostus, 339.

heterogyrus, 336.

keokuk, 333, 348.

levis, 341, 342, 343, 344.

limaformis, 339.

major, 334, 335.

plicatus, 342, 344.

pustulatus, 344.

rectus, 345.

salopiensis, 339.

. spectabilis, 338.

. Sulcatus, 343, 344.

. tenuistriatus, 335.

Ctenodus, 411, 412.

Crenopetauus, 484, 511.

C. crenatus, 513.

C. medius, 513.

C. serratus, 484, 512.

Ctenoptychius, 412, 457, 484, 508, 511, 512, 514.

C. apicalis, 484,

C. dentatus, 511, 514.

C. macrodus, 514.

C. serratus, 484, 511, 512.

Cyclostomata, 328.

S560 eoeece os sosoccsa

Dactylodus, 484, 500.

D. inflexus, 500.

D. princeps, 484, 503.

Dettopus, 410, 415, 417, 427, 436, 441.
D. aliformis, 431.

D. expansus, 431.

D. grandis, 438.

D. sublevis, 414, 428, 431, 432, 437, 438, 448.
Dettorrycuius, 410, 415, 417, 428, 432.
D. acutus, 414, 417, 433, 434, 435.

‘D. gibberulus, 435.

Dendrodus, 524.

Dens tritor rugosus, 459, 460.

Derbyshire, Mountain Limestone of, 542. —

 

Dicurropus, 389, 409. 4
D. scitulus, 410.

Dictea striata, 492.
Dinyuevs, 478, 479, 480.
D. woodii, 478.

Diodon, 521, 522.

D. maculatus, 521.
Diodontopsodus, 519.
Dipnot, 328.
Dreriacantuus, 360, 363.
D. falcatus, 365.

D. stokesii, 360.
Drepanacanthus, 370, 371.

Elasmobranchii, 328, 330.
Enneodon, 521.
ERISMACANTHUS, 364.

K. jonesii, 365.

Farlow, Limestone at, 541.

Gampsacanthus, 363.
G. typus, 363.
Ganoidei, 328, 340.
Gtossopus, 509.

G. lingua-bovis, 510.
G. marginatus, 510.
GLyPHANODUS, 386.
G. tenuis, 386.
GNATHACANTHUS, 363.
G. striatus, 364.

G. triangularis, 363, 364.
Gymnodonts, 521.
Gyracanthus, 533.

Harpaconpus, 484, 511, 512, 514.

_H. clavatus, 515.

H. dentatus, 484, 514, 515.

Hetopvus, 397, 400, 403, 412, 415, 416, 438, 451
456, 508.

acutus, 455.

clavatus, 455.

crassus, 453.

didymus, 403, 407.

expansus, 457.

gibberulus, 405, 411.

levissimus, 399, 404.

mammillaris, 403, 406.

nobilis, 452.

planus, 403, 439, 440, 441, 453.

richmondiensis, 456.

. rudis, 457.

. sinyplea, 456.

. subteres, 399, 400, 411.

. tenuis, 354.

. triangularis, 456, 457.

. turgidus, 403, 453, 499.

Flolocephala, 329.

Homacantuus, 351, 361.

Hf. arcuatus, 362.

H. microdus, 361, 362.

H. macrodus, 362.

Homatopus, 481.

H. trapeziformis, 482.
'' 

©

H. quadratus, 482.
Hook Point, Limestone at, 538.
Hybodonts, 870, 388, 507.
Hysopontip#, 331, 332.
Hybodus, 333, 334, 346, 372.

Ichthyodorulite, 334, 346, 370.

I. brevis, 337.

I. curvicostatus, 525, 526.

Ireland, Mountain Limestone in South Eastern
portion, 538.

Janassa, 331, 486, 488, 489, 490, 491, 492, 511,
518.
J. bitwminosa, 491.

Lagpopus, 468.

L. planus, 470.

L. prototypus, 468, 470.
Leptacanthus, 333, 346, 347, 351, 352, 362.
L. jenkinsoni, 346, 347, 351.
L. gunceus, 346, 350, 351.

L. occidentalis, 333, 347.

L. priscus, 346, 358.
Leptocardii, 328.
LispacantuHus, 359.

L. gracilis, 359.

L. retrogradus, 359, 360.
Localities, Description of, 535.
Localities, tabulated list of, 545.
LopHopvs, 387, 389, 397, 403.
L. bifurcatus, 408.

L. didymus, 407.

L. gibberulus, 405, 406.

L. levissimus, 404.

L. levis, 409.

L. mammillaris, 406, 408.

L. reticulatus, 407.

L. sinuosus, 409.

L. serratus, 408, 409.

Marsipobranchii, 328.
Mesocompuus, 470, 472.
M. lingua, 471.
Myuacopus, 480.

M. quadratus, 480, 481.
M. sesamini, 481.

Mytax, 479, 480.

M. batoides, 479.
Myliobates, 490, 491, 492.
M. aquila, 488.

Nemacanthus, 358.
N. priscus, 358.
Northumberland, Limestone of, 543.

Onchus, 342, 344, 346, 370.

O. hamatus, 370.

O. plicatus, 342.

O. rectus, 345, 346.

O. sulcatus, 343.

Oracantuus, 525, 528, 530, 533,
O. confluens, 525, 526, 528, 529.
O. milleri, 525, 526, 528.

TRANS, ROY, DUB, SOC., N.S., VOL, Ip

 

599

O. minor, 525, 526, 528, 529.

O. pustulosus, 525, 526, 528, 534.

Oreton, Limestone at, 541.

OroponTID&, 331, 386.

Orodont, 400, 512.

Oropus, 331, 387, 388, 389, 390, 403, 407, 410,
412, 420.

. angustus, 394, 395.

. carinatus, 394.

. catenatus, 395.

. cinctus, 391, 392.

. compressus, 393, 394.

. elongatus, 393, 394, 395, 399.

gibbus, 395, 396.

mammillaris, 398.

moniliformis, 397, 398.

ornatus, 397, 398,

porosus, 393.

ramosus, 390, 391, 392, 393, 438.

. reedi, 398.

. Sculptus, 392.

. subteres, 399, 406.

. tenuis, 399.

. timidus, 390.

OSOCSOCSCOCOCSS005059

PALHICHTHYTES, 328.

PETALODONTIDA, 331, 483, 484, 488.

Peraopus, 331, 381, 412, 415, 483, 492, 493, 496,

498, 499, 507, 508, 512, 516, 518.

. acuminatus, 483, 494, 497.

dentatus, 514.

. destructor, 496.

. grandis, 496.

hastingsia, 483, 484, 493.

inequilateralis, 497, 498.

levissimus, 483, 493, 494.

. linguifer, 497.

marginalis, 483, 494.

. radicans, 483, 499, 550.

. rectus, 483, 494, 498.

. recurvus, 497.

. rhombus, 494.

. sagittatus, 483, 516.

P. serratus, 512.

Peraropopsis, 498.

P. tripartitis, 499.

PreraLtoruyncuvs, 331, 484, 485, 486, 489, 490,.
491, 492, 511, 516.

P. pseudosagitiatus, 518, 519.

P. psittacinus, 484, 516, 519.

P. sagittatus, 484, 518, 519.

P. spatulatus, 518.

Prtropvs, 387, 389, 400, 438.

P. patelliformis, 400.

Pharyngobranchit, 328.

PHODERACANTHUS, 533.

P. grandis, 534.

Piychodus, 418.

Puysonemus, 349, 367.

P. arcuatus, 367, 369, 370

P. attenuatus, 369.

P. gigas, 368.

P. hamatus, 370.

P., subteres. 368, 369, 370.

NRW yh yh

4U
''Pinacopvus, 476, 479, 480, 481.
P. gelasimus, 477.

P. gonoplax, 477.

P. sesamint, 481.

_ Placodermic Ganoids, 528.

PLaGiosTomaTa, 329, 330, 331, 528.
Platycanthus isosceles, 525, 526, 527, 529.
Pleuracanthus, 355, 359.

Prixvuropus, 401, 458.

P. woodi, 458.

PievrocompnHus, 471.

P. auriculatus, 472.

Pnigacanthus, 529.

Pacitopvs, 410, 413, 415, 417, 427, 432, 441, 447.

P. aliformis, 413, 431, 441.

P. angustus, 414, 441, 449.

P. corrugatus, 444.

P. foveolatus, 413, 445.

P. gibbus, 445, 446.

P. jonesii, 413, 414, 441, 442, 443, 444, 445, 446.

P, obliquus, 413, 414, 441, 443, 444, 446,

P. parallelus, 413, 414, 427, 428, 430, 441.

P. sublevis, 413, 414, 427, 428, 441.

P. transversus, 413, 414, 441, 442, 443.

Po.yruizopus, 415, 484, 485, 495, 496, 499, 508.

. attenuatus, 503, 505.

. colei, 500.

. constrictus, 506.

. elongatus, 500, 503, 504, 506.

. nflexus, 500.

. Littoni, 504.

. magnus, 483, 484, 499, 500, 503.

P. prasensis, 506.

P. porous, 500.

P. pusillus, 499.

P. radicans, 500.

P. sinuosus, 503, 504.

P. truncatus, 500.

PRISTICLADODUS, 382, 383, 384, 386.

P. concinnus, 385.

P. dentatus, 382, 383, 384, 389, 390.

P. goughi, 382, 385, 389.

P, springeri, 383. *

Pristopus, 519, 520, 521, 522.

P. acuminatus, 520.

P. falcatus, 519.

-PSAMMODONTID, 331, 332, 459.

Psammopvvs, 331, 332, 411, 412, 415, 420, 438, 451
459, 463,518. ,

P. canaliculatus, 459, 460.

P. cinctus, 453.

P. contortus, 411, 421.

P. cornutus, 463.

P. gibberulus, 405, 411.

P. infleaus, 460.

P. levissimus, 404.

P. linearis, 411, 508.

P. longidens, 411.

P. magnus, 411.

P. porosus, 411, 459, 460.

Sy hs toh igh

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600

. reticulatus, 411, 460.

. rugosus, 411, 459, 460.

. rugosus, var. porosus, 459, 460, 461.

. subteres, 399, 400, 411.

. tenurs, 411.

Psepuovus, 403, 410, 415, 416, 419, 420, 428, 438,
P. magnus, 403, 414, 416, 439, 453.

Piychodus, 411, 412, 415.

Soebe Soro Se

Ruampuonus, 389, 401, 408.
R. dispar, 402.

Rhinoptera, 490.

Lhizodus, 624.

Ruymopus, 473, 476.

R. oblongus, 473, 474.

R. transversus, 473, 474, 477.
hynchodus, 330.

SanpaLopus, 410, 436, 437.

S. morrisii, 437, 438.

Scotland, Limestone series of the west of, 544.
Selachoidet, 329.

Sphenonchus, 378.

S. conicus, 378.

Squalides, 381.

Squaloraja polyspondyla, 401.
STIcHACANTHUS, 371, 531.

S. coemanst, 532.

S. tortworthensis, 532.

StrREBLoDvS, 410, 415, 422, 423, 425, 428, 436, 437.
S. colei, 425, 427.

S. egertoni, 426.

8. olongus, 414, 422, 424, 426, 427.

| Strophodus, 411, 415, 451.

S. longidens, 411.
S. magnus, 411.
S. reticulatus, 411.
S. tenwis, 411.

Teleoster, 328.

Thecodus, 415..

Tomopus, 410, 446.

T. convexus, 414, 446, 447.

Venustodus leidyi, 402.

Waterford, Limestone at, 539.

; Xystracanthus, 370.

Xystropus, 410, 415, 428, 447.
X. angustus, 414, 449.

X. egertoni, 450.

X. pulchellus, 450.

X. striatus, 414, 448, 449.

Yorkshire, Mountain Limestone of, 543.

Zygobates, 490, 491, 492
Z. marginata, 488.
'' 
''Dusit: Printed by ALex. Tuom & Co., 87, 88, & 89, Abbey-street,
The Queen’s Printing Office,
For Her Majesty’s Stationery Office.

 

1063.—1,000.—6/82.
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