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,;EFEliFK-::t

"UiriONKM IS UARIS PBOFVSDO QVABBl,"—Pi.iin XII, t.

NOTES ON THE UNIONID^E FOUND IN
THE WCINITY OF OTTAWA, ONT.

F. R. Latchford, B. a.

^ JAD BEFORE THE OTTAWA FIELD NATURALISTS* OI.UB, IOtH MARCH, 1882.]

The family oflamellibrancli niolluskH known as the Uniovidce is represented
in every part of the world, but with a very irregular distribution. While only
thirteen species are found in Europe, and about fifty recorded from Africa and
one hundred and eighty from Asia and the Islands of the Pacific, more than
seven hundred have been described from North America. Fully a hundred of
these occur in the Ohio River alone; |and in Georgia, the Carolinas,
Alabama, and the Southern and So'.ith-Western States in general, almost every
stream has its peculiar forms. Towards the north and east the species become
fewer and fewer, until only eleven are found in Massachusetts. In Canada a
much greater number have Iteen found by Messrs. D'Urban, Bell, Billings
and Whiteaves. In a paper read before the Field-Naturalists' Club in 1880,
Mr. Heron noted twelve species from the vicinity of Ottawa. Tliere are, how-
ever, at least twice as many to be met with here, within a radius of forty miles.
The very low state of the riverb in 1881 afforded me for collecting Unionidce •
facilities of which I had ample leisure to avail myself during the midsummer
vacations. I have in my spare time since then studied carefully these humble
creatures ; and, not content with my own determinations, have taken much
pains to have the species collected identified by the l)est authorities. A M have
been checked or named by such eminent couuhologi.sts as Mr. Arthur h , Gray,
of Danversport, Mass., Mr. George W. Tryon.of the Academy of Sciences,
Philadelphia, and Prof. J. F. Whiteaves, F.G.'i., of the Geological Survey of
Canada. I am therefore certain that, except perha))8 in one or two instances,
the shells which I found have ljeei> r.u.^rectlv determined.

The species met with belong to thegenera Unio, Margaritana,and Anodonia.
These are distinguished from one anoth <r more by the conformation of the
shells than by any peculiarities of the a; nals themselves. Hence it is of the
shells alone that most works on the Unionidce treat ; and from this course it
is not my inten on to depart at present. The shell itself wjll always enable
the student to distinguish one species from another. But the soft parts are by
no means^undeserving of attention. In species of the same group they are
very much alike. In species of different groups, for instance in U. rectus and
U, occidens, they are so dissimilar that the least practised eye can perceive
differences in their form and arranKcinent. In all cases tliey pre'«' > the same
admirable ordination of structure to purpose that we see elsewliere tiirougliout
the works of nature's God. Even the distribution of the I'liionuhe is provided
for, by their young bein^ for a time endowed with liookH by which tiiey can
attach themselves to contiguous objects — often the fin ot a tish or the loot of
a water bird — and be transported far from their place u\ l>ii'th, In the winter
and spring the young, having already well formed shells, are e.xtruded from
the brai.chial uterus of the females In hundreds of thousands and even mil-
lions. According to a computation made by Dr Isaac Lea, of Philadelphia,
who has during fifty 3'ears studied Unionidce, and describe.! almost half the
species known, a large specimen of U. muUiplicains,Lea, contained upward of
iiiree millions of embryonic young. Nearlv all perish early in their free life,
being devoured by fishes, crustaceans and tlie larvte of many kinds of insects.
Their food con.'iots of algae, infusoria and entomostraca, which are drawn in
through the branchial orince to the mouth, at the same time that oxygen is
supplied to the lamelliform gills. Nor is it only by eliminating from fresh
water minute organisms which render it injurious to human life that the
C/niont'dtB are designed to exercise a beneficial influence on mankind. Were

1 460H : PROVINCIAL library,

VICTORIA B. C.

LZ6\

' 8

it not for the immense quantities of lime which they absorb to form their sheila,
tlie water oflimestone regions would be so "hard" thatjt would be unfit without
chemical tieatnient for domestic or economic uses.

Genus Unio, Phillippaon.

Shells of the genus Vnio are readily distinguishable from those of
Margnritana and Anodonta, by their having both cardinal and lateral teeth.
The genus, according to Jeffreys, was established by IMiillippson in 1738, but
it is generally attributed to Petz, who happened to be chairman ofthe meet-
ing at which Phillippson read his " Viaaertatio Siatens Nova Teataceorum
Genera."

Unio complanatua, Uolander, is our commonest species. Abounding in
almost everv stream and lake, it is subject to much variation in size and
coloring. VV^hat may be regarded as the typical form is common in the
Rideau everywhere and in the Ottawa above the Chuudidre Falls. It is a
moderately thin, biown, depressed, sub-rliomboidal shell, with a nacre of
different and often of exceedingly beuutifiii Hhades of purple. The average
dimensionsof ten shells, five from each riyer, are as follows: length 3'5 in.,
height 1*7, diameter 0-8.

In company with the tvpical form, I found near Skead's Mills, in 1880, a
specimen ot a small variety which is of considerable interest. Although
presenting everv appearance of maturity, it is only an inch in height by two
and a halt in length. For its size it is very thick and regularly inflated. I
am informed thata similar vurietyoccurs in some streams in Western New York.

A form almost as small is found in the cold, clear waters of Meech's Lake.
But it is a thin and not a thick shell; not inflated but depressed. Its color
is a very light brown .

About half a mile from Meech's lak'*, un the creek through which it finds
an outlet, are a few shallow ponds, with a bottom of coarse sand and gravel
washed down from the surrounding hills In the warmer water ot these
ponds, where food also must be more abundant, U. complanatua is three times
as large as in the neighbouring lake. It also differs from the lake shell in
bemg proportionately less depressed, and more equally rounded at both
extremities. Its color is ii rich dark brown with a silken lustre, and, not
unfrequently, a tinge of bright orange <»!ong the umbonal slope.

Near the lower end of Duck Island, about seven miles doWn the Ottawa,
there occurs a form o( much interest on account o( its curious angular infla-
tion. Ilow extraordinary this is for species whose most constant characteristic
isits HatiiesH, may be inferreil from tne fact that a representative specimen
whose height is I'G in. measures 15 in. in diameter. The inflation is greatest
near the dorsal margin behind the liinge-lis;ament, where a section ofthe
shell would be an almost perfectly equilateral triangle with the base and the
angles at the base slightly rounded. A specimen found by Mr. Poirier is 3 in.
high, 4-9 long, and weighs T\ oz. Ten ot the shells from Meech's Lake weigh
only 3 oz.

At the same locality is found a still more remarkable variety and one of
no little bv:auty. In some respect" it resembles U. Jialeighenaia,*L^a,trom
North Carolina, and in others, U. tortuosua, Sowerby, an Asiatic species.
It IS like the former in shape and in the numerous prominent rays which
diversity its surface ; and like the latter in the strange peculiarity that its
valves meet at the ventral margin not in a straight but in a sinuous line. A
correspondent writes that under Dr. Lea's treatment it would be entitled to
rank as a species. Whether regarded as a mere variety of U. complanatua or a
distinct species, it is a unique and most interesting shell.

Unio gibboaua, Barnes, appears to be rare, having occurred to me only in
the Ottawa near Gilmour's Mills and at Templeton, always in deep water.
It is a brown, elongated shell, attenuated posteriorlv, and with the dorsal
margin regularly curval. It bears a slight resemblance to some forms cf
U comj>lanatua', but may always be distinguished by its heavier shell, the
deeper purple of its nacre, and especially by the great thickness of the
lamellar tooth in the right valve,

CTtto e^/{p«t8. Lea, is not uncommon on sand bars below Kettle Island,
but does not seem to occur in the Uideau or in the Ottawa above this city.
Il differs from all other species here observed in having the beaks very near
the anterior end of the shell, where the muscular impression is of great depth
and the shell itself of great thickness. The cardinal teeth are parallel to
the lateral teeth and not placed at a right or oblique angle to them as in our other

spfc

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in el

tellsl

that!

species. The nacre of many HpecinienH is beautifully iridescent, displaying
the colors of the prism and rainbow, chastened, soflened, and made per*
petual .

Unio rectus, Lamarck, which in easily recognized by its dark colocr.
and elonsated form, is found in conHidsruble nunilters in the Uideau near
Billings' Bridge, but is comparatively rare in (he Ottawa. The ground color
of the epidermis, which at tirHt appears black, proves on closer examinHtion
to be yellow, profusely rayed with broad lines of very dark green. Young
shells occasionally hare a purple nacre, but in mature tapecimens only a trace
of this is seen along the lateral teeth and in fhe cavity ot the beaks. Where
I^. com/>/ana<u« is found of the normal size in the Uideau and at the Chats
Hapids in the Ottawa, U. rectus is very large — not unfrequeiitly exceeding
six inches in length. But at Duck Island, where U, complanatun attains an
uncommon size, U. rectus is small, though in verv fine condition. In fact,
all the shells found at this wonderfully prolific locality, with the exception of
F. borealii, are in an excellent state of preservation.

r^/iio radia/u«, Lamarck, is common almost everywhere in the Ottawa
above the Chaudi^re. At the fuot of the rapids near Mechanicsville are a
number of islets along whose shores, when the river is low, there may be seen
large heaps of shells, of which this Hpecies constitutes no iiicunsiderubii* part.
The muskrat lives chieflv on the ITnionida;', and these heaps are the remains
ot his nightly repasts. I have obtained from them home of my best »'i)ecimeiis
of U. radiatua. At the Chaudiere, itseldom attains n greater length than three
inches, but is much larger in the Deschencs Luke, above Britannia. It is a fiat,
obovate shell, of a green, olive or reddish color, with numerous narrow rays.

UiUo luteolns, Lamarck, atiounds in the Rideau Canal from the Sappers'
Britigc upward, and is not uncommon in the Rideau River. Its color is from
a greenish yellow to a dark olive, with distinct, dark green rays. In shape
il varies even more than in colour. Some shelli» are ho innated as to be
almost cylindrical ; others .^o depressed that they ciinnot, when the beaks
are eroded, be distinguished by any external clmmcter from U. rwliatus, .
Having probably stu<fied only the exterior o( the two species, an esteemed
western correspondent writes that they merge into one ano'.her in Toronto
Bay. I doubt whether they can possibly l>e more alike in Lake Ontario than
they «are sometimes tiere, and however great their outw.ird resemblance, I
find tliat they always differ internally, especially in the form of the cardinal
teeth. Ill U. radiatus these are short., erect, and triangular. In U. luleolua,
they are long, curved, compressed and oblique.

IT/Mo mrib»M», ^'ay, occurred to me near Black Ray, Eardley, Quebec,
where I was searching for nodules and fossils in the Champla i Ciayt*, whi< h
there form the north shore of the Deschenes Lake. It is a th , small, ovate,
inflated shell, of a yellowish color, with a few indistinct, rays. Some
speciiuens of an accompanying species of Le(/a, which lived when the clays
were deposited in the post glacial period, would be taken for recent shells, so
well have they preserved their thin, delicate epidermis and fragile teeth
through the many thousand years that have elapsed since then.

Unio occidtns. Lea, is quite abundant in the Ottawa, near the mouth of
the Gatineau, and along the sandy shores of Duck Island. Its shape is
remarkably uniform, varying only with the sex. It is an ovate and very
much inflated shell, with large prominent umbones and closely approximate,
recurved beaks. The females are more broadly inflated than the mules and
of a triangular shape, on account of which peculiarities they are liable to
be confounded with U, ventricosua, Barnes.

For beauty and diversity of coloring, there is not probably found in the
world a fresh water shell which surpasses the Unio occidenaoC the Ottawa
River. When young it ia of soft and varied shades of yellow, green and red,
the primary spectral colors, and sometimes of all three together. Mature
spfcimeus are rich as ai^ autumn landscape in tints of yellow-brown and olive-
green. All — but especially the young shells — hnve a porcelain-like lustre,
which it seen at its best, when on a sunny day they lie on the clean, white sand,
with just enough water to cover them. Then they shine and glow like
opals. Moreover, their changeful colors are so differently combined with
ruys — sometimes few and sometimes many, fine as a liair or iiroud almost as
an iris leal — that, among hundreds of specimens collected, no tuo were alike
in every respect. Each is, accordingly, a unio, in the exact sense that Piiny
tells us the word was coined to express. " From the circumstance, he sayE
that uo two pearls are ever found alike, Roman luxury called a pearl ^»to,—>

from umu, one^theaning a uniqu*; production. " The barbariftDS who found
the pearlf) called them mcwgaritae.

That U. oeeidens, under precisely the same conditions of l>fe, should
secrete in almost infliHte variety so many different colors itt a fact which
challenges attention.

Unio mbovaiun. Lea, which is found in the Rideau Canal and River, is
chiefly remarkable For the large size to which it sometimes attains, a specimen
from the canal beyond Uurtweli'H Locks measurirg 4 5 inches in length, 3'4
in height, and 2*2 in diamet<>r. In the river it is smaller and more eroded
than in the canal. Good shells, however, are to be found near Mr. D. O'Cun-
Dor's summer residence. This species bears especially when young some
resemblance in color and outline to U. Occident, of which Say considered it
only a variety. His opinion on this point is now held by very few; and I
hardly think that anyone who compares the two shells as they here occur would
venture to pronounce them specifically identical. U. 'aubovatut is less
inflated than U. oeeidens, and less approximate at the beakt<, while with
respect to beauty there can be no comparison between tliem.

Be8ide»the curious spiral follicle of the larva of a phryeanaceous insect,
Helicopsyehe arenifera, which was first described as a mollusk of the genus
Valvata, I have observed on the valves of 17. aubovalus. and other la^ge
species from the Rideau River,a small isopod cruxtaceun, which is worthy of
note as being probably the best living, though degenerate, representative of
the trilobites that once abounded here on the low tidal flats of the Silurian
seas. It is, I think, Fliivicola Herrickii, De Kay.

Unto alatua. Say-, was found here by Mr. Heron in 1880, and was recorded
from " Ottawa River, near Ottawa," twenty vears ago, by Mr. Whiteaves in
a valuable paper published in the Canadian I^aturaiiHt. It whh also found by
Mr. Hubert Bell in the Ottawa at the mouth of the River Rouge, a locality I
have not yet been able to visit. There are a few fnecimeiis in the museum
of the Ottawa Iiiterary and Scienliflc Society, which were probably collected
by Mr. Bell. As I have not met with it on my many exciirsionc, I think it
must be n>re in this vicinity, or at least restricted tu a small area. It is the
only species found here in which the wing rises higher than the right line of
the hinge margin. It occurs from Tennessee to Vermont and westward to
Nebraska and Manitoba. Certain other species, as U. apinosua. Lea, attd V.
Shepardianua, Lea, are said to be confined within narrow limits to one stream.

Unio gracilia,Bamea, is another winged species which has not, till now,
I believe, been recorded from any locality in Canada east of the Welland
Canal. It is not at all common, Mr. Poiner and myself having found only
five or six specimens during the summer. These were collected on sand bars
in the Ottawa between Duck Island and the Ontaiio fhore. It is an exceed-
ingly thin and fragile, depressed, sub-triangular shell, of a greenish yellow
color. The hinge margin is straight and prolonged into a large wing, uniting
the two valves. It may be distinguished from 17^. a/afiilL by its greater fra-
gility, lighter color, both inside and out, and by its differeinly formed wing.

Unio preaaut. Lea, was found by Mr. Tyrrell, of the Geological Survey,
in the Rideau near the Rifle Range. Only one specimen was met with, and
that he has with grpat kindness presented to me. It is but liitie more than
two inches in length, very much flattened, and the hinge margin is straight
with a 8li>.htly alated projection. The beaks are finely undulated. Its form
and exter.jal color, together with the shape of its cardinal teeth, seem to con*
nect it Ath the margariianae.

[I have since collected a number of large U.preaaua in excellent condition
along the right bank of the Rideau, from the Utica Slate outcrop near the
Sparks' homestead up to Hurdman's. Over this area it is found sparsely
scattered in muddy pools in the rapids; but it does not occur in the next
rapids above at Billings' Bridge, nor thence upward. Mr. Weston while col-
lecting fossils at Paquette's Rapids, at the foot of Allumette Island (about
45° 50 N) picked up a dead U. presaua. This is the most northerly locality
at which the species has been found.]

Unio Canadenaia, Lea, was originally described from the St. Lawrence
near Montreal. Both Mr. Tryon and Mr. A. F. Gray have referred to thin
species some shells which I collected in Nepean Bay. Mr. Gray writes: "It
seems to agree well with the characters of u. Canadenaia, and with Dr, Lea's
figure. From these data, and without a typical shell with which to compare
it, I am justified, I think, in referring it to that species." Mr. Tryon saya :

1-6J
surl
diaf

fin<^

TryJ

'* I regard * aheli which you sent iiie from N«pe*n Bay as the (rue V. Cbna-
denaU." It appears to be rare, only a few apocimens having been found. It is
somewhat compressed, of an oval shape ana darlc olive color, with indistinct
rays.

Unio^borealis, A, F, Gray, is a new species. It occurs in the Ottawa,
from the moutli of Brighani's Greek to Templeton,and probably much farther
down. Although common, it is very seldom met with in good condition.

I first submitted this shell to Mr Trvon, but the only specimens I had to
send were so budly eroded that they cSt^ld not Ite determmed. A second lot,
little if any better, led him to think it doubtfully referable to U. luteolttt,'
from some forms of which the females are not easily distinguishable. Not
until October ot the past year did I succeed in collecting specimens which
had the undulations ol the beaks well preserved. I was led to eo out so late
in the season by a letter from Mr. A. F Gray, relating to the shell in question,
of which I had sent him speciniens a short time previously. He regarded my
views as correct, that it differed essentially from both I', luteolua and if.
radiatua, but thouglii that further study and comparisons mi);ht prove it to
possess affinilies with some other described specicii, and cxpressea a wish to
see a large series of the l>est shells I could obtain. On my next holiday I
went down the river tc Duck Island and collected a numlier of male and
female shells, including a few in fine condition. I despatched these to Mr.
Oray on the day following, but lieard nothing more about them until Feb-
ruary 28th, when I I'eceived the pleasing;, though not unexpected information
that the shell was undoubtedly new. The names U. beUus and U. horealia
were suggested as appropriate. The latter seems the more fitting, and the
species will accordingly be known as Unto borealia, A. F. Gray. A defcrip-
tion, promiseii at my request, has not yet been received, and I do not wish lo
refer more particularly to the shell to-night, lest I should in any wav interfere
with the prioritv o' my friend's description. The right of naming tT. boreatia
belongs to Mr. dr..,, as he was the first to recognize itu specific distinctness
from any described nni'o.

[Mr. Gray's description was received some time after the reading of my
paper, and is here given in full :

Unio Boreams, — A. F. Gray.

Shell smooth, broken only by numerous ridges of growth ; obovate, very
much inflated in the female form, the male more compressed, very inequil-
ateral, obtusely angulated behind and rounded before, the basal or ventral
margin rounded, beaks badly eroded and but slightly raised ; ligament thick,
moderately long and dark brown; unbonal slope flattened, and but slightly
carinated ; epidermis variable, some specimens dark olivaceous brown with
broad obscure rays of dark green, others yellowish green with numerous fine
rays of a brighter green, cardinal teeth rather large, somewhat compressed
and corrugate ; lateral teeth thick, slightly curved, and with crenulate mar-
gins ; anterior cicatrices distinct, that of the adductor muscle very deeply
impressed; dorsal cicatrices posterior to the centre of the cavity of the bealcs;
posterior cicatrices confluent and but sliditly impressed; cavity of the shell
deep and rounded ; cavity of the beaks obtusely rounded and deep; substance
of shell very thick, thickest liefore: nacre usually white, occasionally rosy,
and sometimes a beautiful pink, and beautifully iridescent.

Transverse diameter, 3-15 inches; altitude, 1*95 inches; lateral diameter,
1*65 inches. These measures are from a large female. A male shell mea-
sures : transverse diameter, 315 inches; altitude, 1*90 inches; lateral
diameter, 1-.35 inches.

For this beautiful shell, and the privilege of describing it, I am indebted
to Mr. F. R. Latchtbrd, of Ottawa, Ontario, from whom I received quite a
large series of this Unio, which belongs to the group of which Unio luteolua
of Lamarck may be considered the type. It differs from that species in being
shorter transversely, in having a much thicker shell, and having the beaks
badly eroded. In its outline it bears a close resemblance to Unio radiatua.
Lam., but is more inflated and has a heavier shell. It occurs in the Ottawa
Uiver at Duck Island ; it has also been found at Leamy's Lake, near Hull,
in the Province of Quebec.

The variety with pink nacre has a bright orange-brown epidermis with
fine rays of dark green

^■.^■^■^

'After the aliove was written, I lent lome yonn^ gpecimens of V. hortalis. A. T. Oray, to Hi,
Tt]roii,'UUl tboy have couvlnoed him, be iafonua me, tlut the tpeolet U new.

A young specimen in more elongated transverBely has perfect umboueH
which Nhow four well developed folds, and liaH a rugoite poaterior alope simi-
lar to Margaritana rvgosa, liarncH.

The fioft parts ha^ not been prcnerredi in conHequencei their arrange*
ment cannot w deflcriUed.]

Ogki'h Makoakitaka, Schimacher.
The Hhell of tliix genun dillerH from tliatui Unio in having no lateral teeth.
Thexe, however, are not always entirely wanting in M. margaritif'era, the
celebrated pearl nuisnel of Great Britain am! the North Atlantic and Pacific
Itorder regionn of America. Alihongii common eastward in Quebec and to
the south in New York and Vermont, it has not yet been tound in this
vicinity.

Margaritana mnrginata, Hay, occurn nparHcly in the Rideau and Ottawa
in rapid water, which', indeed, in the favorite habitat ot our other species also.
It is small, seldom of greater length than two and a half inches, moderately
ihin, and transversely wedge-shaped. In color it ranges from a dusky green
to a deep brown, with indistinct dark rays. The shells found h^e are much
inferior in size and coloring to specimens of the same species received from
the Mohawk River, New YorTc.

Murgaritana undnlaia. Sag, is rare in the Rideau and is not common iiT
the Ottawa, whcic tiie least unproductive locality that I know of is above the
Little Cliaudidre along both shores of the river. In Meech's Creek it is quite
plentiful, esjiociaily mar llie ulmndoned rubber factory. It is smaller than M.
marginata, proportionately more inf1u'"d, brighter in color, often so bright as
to be really beautiful. The distant .Dncentrio and prominent waves on the
umbones from which it derives its specific name, are seldom apparent except
in young shells. Many old specinutis are as thick and strong anteriorly as a
/7. cWjps»V» of the same fi/e, while towards the posterior margin they are as
thin and fragile as the mcst delicate anoJonta; and thus, as well as by
having cardinal and no lateral teeth, Jf. umlulata unites in itself two of the
most distinctive characters of the genera between which, in the plan of crea-
tion, Margaritana has been assigned its pl.^ce.

Margaritana rvgosa, Barnes, the largest we have of the genus, is abun*
dant a^ many points along the Rideau, but is quite rare in the Ottawa. As
found in the furmer stream it res<>mbles the typical U. complanatus in shape,
but is of a greener color, and may, moreover, be easily distiniruished from
that shell botlt by the wrinkles along the post-lateral margin and, of course,
by the absence of lateral teeth. A shorter, truncated form is occasionally met
with in the same river.

I observed a few large and exceedingly fine specimens of this margaritana
at the Chats Rapids, where I found them in a mixed company ofuniones and
anodontae, thirtv-three in number which were living together in an open
space between tfie rocks but little if any more than a square foot in extent.
Ihey were green in color, and had the characteristic wrinkles prominently
developed. One shell exhibited in a marked degree the strange deformity that
its valves did not meet in a straight line, but, an inch ur more from the pos-
terior end, were bent sharply aside about forty degrees. I have noticed a
few less striking insta .ces of similar distortion in tlie same species from the
Rideau. They are probably due to injuries received when young through
coming into violent contact with a stone or pebble. To such' a mishap the
young of this species must often be exposed in the rapid water they frequent.

Genus Anodonta, Bruguiires.

The transition from Margaritana to Anodonta is b^ no means abrupt:
nihil in naturaper saltum. It is made easy by a shell found here, which was
first described by Say, and placed by him in the former genus — or rather m
the genus correspondiMjg to it that he had instituted, alasmodonta, — but which
is at present universaflv referred to the latter, This species is now known
as Anodonta edentttla, !^ay. Although its name expresses w!iat may be called
the reduplication of toothlessness, the shell is slightly exceptional to the best
marked character of the genus — the absence of both cardinal and lateral teeth.

Anodonta edentula. Say, like its relatives the margaritance, is to be found
in water flowing rapidly over a rocky bottom. The best localities along the
Ottawa that I have met with are the 'Little Cbaudidre and Chats Rapids. \

fil
ir

capital place for collecting it and seven or ci^ht other species of
Unionidce is the nnye^ as the lumbermen* cull it, between Mason's
Mill and the opposite island. It is a comparatively thick shell,
generally of a dark olive color; but when the rays are few or
narrow.'the f;round tint, a lisht brown, predominates. In the left valve
of many specimens there is a sliort though well defined cardinal tooth with
a small notch in it snal^gons to the iieep cleft in the primary tooth of the
left valve of Unio and Margaritana.

In the narrowest and most rapid parts of Meech's Creek, and not in the
ponds into which it often expanas, or the lake from which it flows, there
occurs a large though badly eroded form of this shell which appears to be
identical vtiththe variety of A. edentiila described by DeKav,and called by
him, after the river in New York in which it is found, /I. L^H(fdi7/a. It is
more inflated than the A. edentula from the Ottawa, and of a lighter color.

Anodonta undulala, Say, is found in the Rideau near Billings' Bridge,
and in the Ottawa at Kettle Island. It resembles the preceding species so
much that many think the two identical. A. undulala differs from A.
edentula in lieing a thinner shell, more obscurely rayed, and more angularly
inflated. Additional and perhaps mure distinctive characters are revealtxl by
the microscopic examination of the young ol both species. Botanists, as Mr.
Fletcher told us two years ago, cannot always by the leaves and blossoms
alone distinguish Drbsera lojigifolia from Vrosera rotundif'olia, but their
minute seeds present characteristics which place the specific distinctness of
the parent plants beyond all doubt. So also with the embryonic young of
these two species of anodonta. I have not examined them myself; but Dr.
Lea's figures show that they differ in outline, and that while the hooks of A.
edentula end in three points, those of A. undulala end in one,

Anodonta aubcylindracea. Lea, a very distinct species which I have met
with only at the Chats, is one of the most widely distributed shells of the genus
extending hence through the middle and western states as far soiitli as
Louisiana. Uur shell in its ordinary form is iilentical with Dr Lea's type.
It is small, thin, inflated, almost elliptical in outline, and olive green in color,
with indistinct rays. Old shells are ge:ierally abnormal. They are con-
stricted along the basal margin opposite the hinge and so much elongated
that instead of being elliptical they are kidnej- shaped This reniform appear-
ance is observable in old shells of many species of the Unionidce, U, com-
planatua, for instance, and notably M. margariUfera. An examination of tlie
lines of growth will show that altera certain age the shell does not increase
symmetrically. It grows rapidly in the direction of the uinbonal slope,
slowlv in front, and scarctly at all opposite the hinge. The change produced
in this way in tlue form of shells is very remarkable.

Anodonta Benedictii, Lea, occurs in several localities near the city, but
nowhere in great numbers. I have found it at the Chats, and in a small lake on
Meech's Creek. Mr. Fletcher collected a few fine specimens of the typical
form in the Ottawa near the outlet of Leamy's Lake. It is a trapezoidal,
slightly compressed, horn-colored shell. The dorsal margin is nearly straight
ana is extended behind, where it forms a well marked wing.

Anodonta Lewinii, Lea, occurred to me in the Mississippi at Almonte,
where it appears to be abundant. It has a much smaller wing than A.
Benedictii, which it resembles, is more elongated, and somewhat less inflated.
The beaks in perfect spvoimens have sharp prominent tubercles, which are
arranged in a manner ch.: ' 'eristic of the species. With A. Lewisii, I found
at Almonte U. comptanatus, U luleolus, m. }-ugoaa, M. undulala, and A.
undulala.

Anodonta impUcata, Say, is a species of which only a single living speci-
men has been obtained. It was found in a deep pool near the upper end of
the old Chats Canal, after a search of an hour s duration, which 1 was led to
engage in by seeing on the shore a few broken valves of an anodonta not pre-
viously met with. It is a large, thick, olive-brown, elongated, cylindrical
shell, with a salmon-colored nacre.

.^nodontoi^oo^tana, Lea, is not uncommon at the Chats Rapids. It is a

* TheHo liaitiy voyai/cun relisli a dish of "clams" ocvasiunally and obtain thum by an ingenious
procenB. Whik' the rafts are heintj towed slowly down Lake 8t. Teter the men immrrge top down-
ward iu the shallow water, a number of the long biruh withes used for tying the timber. The open
unioa feeling the birch a poiteriori, close upon the withes which are drawn up from time to time
Hnd the iheUi picked off until a aumoiency baa been obtained.

thin, inflated, oblong, browninh ap«oi«8, obacurel? radiated, and tinsed with
yellow pooteriorly. A darker ana leas elongated form from Meech'H Creek ia
•aid to he " identical with HhellH determined by Dr. Lea m his A. Footiana,*'
which are now in Mr.vOray'fl cabinet.

Anodnnta lacutMa, Lea, inhabit* lakoH in the County of Ottawa It in
brown when aged, but young Mu*lln are greeninh yellow. The tuberclen on
the beakf* are arranged in cloxe, concent no waven. Kvery npecimen found in
Septenitier, 1881, in tCidderV Luke, in MnRhani, was infented by hundredn of
small initeH, which moved freely over the surface of the gills. The same
lake, which is about thirty miles from Ottawa, contains a plant, Ertocaulon
teptanffulare, not recorded in tlie " Flora Ottawaensis " of Mr. Fletcher.

AnodoHia fragiUa, Lamarck, is common in Meech's Lake, near the out-
let. It is an elongated, thin, depressed shell of a yellowish colour, with a
straight dorsal margin, and pearly iridescent nacre. That the form regarded
as lacuatria is distmct from this appears to me somewhat doubtful. U.
carioxua is the only other shell which mav not be correctly determined.

/ ite found in the gills of A-Jragilia in Meech's Lake, is as large as a
pellet of buck-shot, and ditl'ers vastly fi-um any species I have ever seen. Mr.
Tyrrell will doubtless soon publish a description of it.

Anodnnta flutiatWt, Dillwun, occurs in great numbers in McKay's Lake,
New Edinburgh, and in the Kiucau Canal \ but is rare in the Utta\ » v here
it is found only in bays in which there is little or no current. In color it
ranges from a bright grass green to an an olive-brown with concentric
yellow bands, and innumerable narrow, obscure rays. Sometimes it attains
a length of six inches, but is generally al)Out a third smaller. Its large size
and Drilliant coloring conspire to make it the finest Auodonta we have.
Toward the end of April, when the ice has melted, and before the water has
been let into the Canal, very fine specimens may be collected at St. liouis
Dam. Still finer, though smaller shells are .to be obtained— but only by
dredging — in McKay's Lake.

Repeated microscopic examinations of the young of this shell lead me to
believe that the only observations which I find published on the youns of the
Unionida are not altogether correct; In his •• Descriptions of the embryonic
forms of thirty-eight species of the Unionidce," Dr. Lea says : *• The btts<!
in all the species always presented the anterior iind the posterior margins
equal, which is not the case with any of the species when fully grown. That
is, ii a perpendicular line be raised from the middle of the basal margin to
the miodle of the dorsal line, the right and the lejt diviaiona will be exactly
aummetrical. " Now, I thought that precisely the contrary was evident when
tne youngof A.fiuviatilia were observed under a high power ; and Mr. Tyrrell
and Mr. Fletcher, whose attention was called to the matter, thought so too.
Dr. Lea, however, to whom I sent some of the young, wrote that on carefully
examining them, he failed to notice the asymmetrical difference which I des-
cribed. Here was observation opposed to observation. To ascertain the
truth with regard to the point at issue, I made use of the fine solar miscros-
cope of the College of Ottawa, which gives a magnification of two thousand
diameters. As the outline of shell after shell was cast upon the screen,
each was observed to l)e decidedly asymmetrical and unequally curved on the
sides. The vounzof U. luleolus and U, borealia proved also to be inequilat-
eral i and I have little doubt that the same want of symmetry obtains in the
young of almost all other species. It seem&, therefore, that Dr. Lea was
mistaken in describing and figuring as symmetrical the embryonic forms of
many species of the Unionidce.

With A.fluciatiHa closes the record of the species so far observed her#.
Extended as it is, for a place so distant from the metropolis of the Unionidae
in the Ohio Valley, it certainly does not include all the forms that occur
in this vicinity. A plana, Lea, and A. FeriraaeiaHa, Lea, a shell which is
found at Montreal and at Toronto, probably occur here; and when the numerous
lakes and streams around our city are more diligently searched, they will, I
feel confident, furnish very material scI ui ons to tlie piesent list of the Ottawa
Unionidce.

k. a. Woonacaii, Printer and PnbUaher, Elgin Street, Ottawa.

UNIC BOREALIS.— A. F. Gray