^ ^ Qs: ^s^s:^=^ =^s;^r^s‘g^aj^:^s$^s05£^z:$^sj^s;j^r^Q ^earniitg aub ^fabor. LIBRARY University of Illinois. CLASS. BOOK. VOLUME. ..'S'sl. N\."^io. 'c \ Accession No. MARYLAND GEOLOGICAL SURVEY EOCENE MARYLAND GEOLOGICAL SURVEY LIBRARY • OF the UNIVERSITY of ILLlNUiS EOCENE BALTIMORE THE JOHNS HOPKINS PRESS 1901 J'rt^bentvafi) Company BALTIMORE, MD., U. S. A. > 0 r >) COMMISSION JOHN WALTEE SMITH, President. JOSHUA W. HERING, DANIEL C. GILMAN, Executive Officer. PRESIDE^fT OF THE JOHNS HOPKINS UNIVERSITY. R. AY. SILVESTER, Secretary. PRESIDENT OF THE MARY'LAND AGRICULTURAL COLLEGE. \ GOVERNOR OF MARYLAND. COMPTROLLER OF MARYLAND. Digitized by the Internet Archive in 2016 / https://archive.org/details/eoceneeocenedepo1190claf ♦ i SCIENTIFIC STAFF W^r. Bullock Clakk, State Geologist. SUPEKIXTEXDEXT OF THE SURYEAT. Edward B. Mathey’s, . . . Assistaxt State Geologist. CHIEF OF THE PIEDMONT DISTRICT. Charles S. Prosser, CHIEF OF THE APPALACHIAN DISTRICT. George B. Shattuck, CHIEF OF THE COASTAL PLAIN DISTRICT. Harra' Fieldixg Eeid, CHIEF OF THE HIGHWAY DIVISION. L. A. Bauer, CHIEF OF THE DIVISION OF TERRESTRIAL MAGNETISM. And Y'ith the cooperation of several members of the scientific bureaus of the Xational Government. LETTER OF TRANSMITTAL To His Excellency John Walter Smith, Governor of Maryland and President of the Geological Survey Com- mission. Sir : — I have the honor to present herewith the first volume of a series of reports dealing with the systematic geology and paleontology of Maryland. A clear comprehension of oiir geological formations is based on a knowledge not only of the materials out of which the strata are composed, hut also of the remains of animal and plant life which are entombed in the rocks themselves. A thorough knowledge of both these factors is essential as a basis for a complete interpretation of the mineral resources of the state, while the educational and scientific value of such information cannot be overestimated. It is the purpose of the Survey to publish a number of similar reports which will embrace the entire sequence of Maryland formations. Already much progress has been made in the investigations for the subsequent volumes of the series. I am. Very respectfully, William Bullock Clark, State Geologist. Johns Hopkins University, Baltimore, Aprils 1901. CONTENTS PAGE PREFACE 15 THE EOCENE DEPOSITS OF MARYLAND. By William Bullock Clark AND George Curtis Martin 19 Introduction 21 Historical Review 24 Bibliography 31 General Stratigraphic Relations 44 Cretaceous 45 Eocene 46 Neocene 47 Pleistocene 48 Distribution of Strata 49 Delaware 49 Maryland 50 Virginia 51 General Character of the Deposits 52 Composition 52 Strike and Dip 53 Thickness 54 Origin of the Materials . 54 Origin of Greensand 55 Depth of Sedimentation 57 Stratigraphical and Paleontological Characteristics 57 Formations and Faunal Stages 58 The Aquia Formation or Stage 59 The Piscataway Member or Substage 60 The Paspotansa Member or Substage 62 The Nanjemoy Formation or Stage 64 The Potapaco Member or Substage 65 The Woodstock Member or Substage 66 Local Sections 67 The Potomac River Section 67 Other Sections 71 Geological and Geographical Distribution of Species 73 Table showing Distribution of Maryland Eocene species 73 Correlation of Deposits 82 Correlation of the Deposits within the Middle Atlantic Slope 82 Correlation of the Deposits with the Eocene Formations of the Gulf States. 83 Paleontological Criteria 84 Geological Criteria 89 European Equivalents 91 12 CONTENTS PAGE SYSTEMATIC PALEONTOLOGY, EOCENE 93 Reptilia. By E. C. Case 95 Pisces. By Charles R. Eastman 98 Arthropoda. By E. O. Ulrich 116 Mollusca. By W. B. Clark and G. C. Martin 122 Mollnscoidea 203 Brachiopoda. By W. B. Clark and G. C. Martin 203 Bryozoa. By E. O. Ulrich 205 Coelenterata. By T. Wayland Vaughan 222 Echinodermata. By W. B. Clark and G. C. Martin 232 Protozoa. By R. M. Bagg, Jr 233 Plantae. By Arthur Hollick 258 Explanation of Plates 261 Genekal Index 317 Paleontological Index 323 ILLUSTRATIONS PLATE FACING PAGE I. Map showing- Distribution of Eocene Deposits in Maryland 21 II. Views of Surface of Eocene Country 44 Fig. 1. — Farm- and wood-lands along South Riyer 44 “ 2. — Farm-lands near Annaiiolis Waterworks 44 III. Views of Eocene Sections 48 Fig. 1. — Zones 2 to 6 at mouth of Aquia Creek 48 “ 2. — Blocks of Zone 9, largely composed of TnrriteUa mortoni 48 IV. Views of Eocene Sections 56 Fig. 1. — Fort Washington bluti', basal Eocene overlying Cretaceous 56 Fig. 2. — Zones 2 to 4 at base of Aquia Creek blutf 56 V. General Columnar Section of Eocene Deposits in Maryland 64 VI. Local Columnar Sections of Eocene Deposits in the Potomac Valley 68 VII. Views of Eocene Sections 72 Fig. 1. — Lower Eocene Deposits on Severn River 72 “ 2. — Indurated layer of Upper Marlboro, overlying Bryo- zoan Sand 72 VIII. Views of Eocene Sections 84 Fig. 1. — Contact of Nanjemoy and Aquia Formations in Valley- of Beard Creek, Anne Arundel County 84 Fig. 2. — Contact of Nanjemoy and Aquia Formations at Upper Marlboro 84 IX. Views of Eocene Sections 88 Fig. 1. — Railroad Cut near Upper Marlboro showing Nanjemoy Formation overlain by later deposits 88 Fig. 2. — Popes Creek bluff showing Zone 17 overlain by Miocene Diatomaceous earth 88 X, XI. Reptilia 262-263 XII-XV. Pisces 264-267 XVI. Arthropoda — Crustacea 268 XVII-XIX. Mollusca — Cephalopoda 269-271 XX-XXVIII. Mollusca — Gastropoda 272-280 XXIX. Mollusca — Gastropoda and Scaphapoda 281 XXX-LVII. Mollusca— Pelecypoda 282-309 LVIII. Molluscoidea — Brachiopoda 310 LIX, LX. Molluscoidea — Bryozoa 311-312 LXI. Echinodermata and Coeleuterata 313 LXII, LXIII. Protozoa — Foraminifera 314-315 LXIV. Protozoa — Foraminifera, and Plantae 316 PREFACE The present volume is the first of a series of reports dealing with the systematic geology of Maryland. These reports will appear from time to time as the several investigations are completed, but not neces- sarily in geological sequence. By reference to Volume I of the Survey it will be seen that the geological sequence of Maryland rocks is as follows: { Pleistocene Neocene Eocene Mesozoic Cretaceous Jurassic-Triassic r Paleozoic Permian-Carboniferous Devonian Silurian Cambrian Archean Algonkian-Archean Some of these divisions are more extensively developed in Maryland than others so that the contemplated reports will differ greatly in size. The oldest division, comprising the Algonkian-Archean, is entirely des- titute of organic remains in Maryland, while the Jurassic-Triassic is nearly so. The other seven divisions, however, contain either rich faunas or floras; three of them, the Permian-Carhoniferous, the Cre- , taceous and the Pleistocene containing both animal and plant fossils. These reports when completed will give both to the geologist and to the general reader a comprehensive view of the past history of Maryland territory from the earliest geological period to the present day. For educational purposes the volumes cannot fail to have much value, and will find frequent use in the hands of those who are seeking to acquire a knowledge of the ph}^sical and faunal history of the State of Maryland. The present volume on the Eocene deals with the earliest period of the Cenozoic and, with the Neocene, embraces what is frequently de- 16 PKEFACE nominated by geologists as the Tertiary. As will be shown in later pages the Tertiary rocks of Maryland are of wide extent and contain much of interest from both a scientific and practical standpoint. The Eocene deposits of Maryland have received for many years the close attention of .the senior author of this paper, and his observations have been supplemented recently by the work of the junior author. A report made by the senior author to the Director of the U. S. Geo- logical Survey in 1896 is extensively drawn upon for the present vol- ume, many of the general descriptions being taken directly therefrom, with such changes and additions as the present enlarged knowledge of the subject may require. Dr. K. M. Bagg, Jr., also spent portions of two field seasons in a study of the local stratigraphy under the personal direction of the State Geologist and prepared a series of preliminary maps covering a large part of the area. The paleontological investigations have been jointly conducted by several experts. In addition to the sections for which the authors of the report are personally responsible, aid has been rendered in others by several well-known students. The Eeptilia have been studied by Dr. E. C. Case of Milwaukee, Wis- consin; the Eishes by Dr. Charles R. Eastman of Harvard University, Cambridge, Massachusetts; the Crustacea and Bryozoa by Mr. E. 0. Ulrich of Newport, Kentucky; the Corals by Mr. T. Wayland Vaughan of the U. S. Geological Survey; the Protozoa by Dr. R. M. Bagg, Jr., of Colorado Springs, Colorado; and the Plants by Dr. Arthur Hollick of Columbia University, New York. Mr. Charles Schuchert of the U. S. National Museum has revised the descriptions of the Brachiopoda. Extensive collections of material were made preparatory to this work, and all the leading fossiliferous localities of the state were visited. The greatest amount of material was obtained, however, from the bluffs along the banks of the Potomac river, which afford the most com})lete section of the Eocene in the Middle Atlantic Slope. In general, the fossils of this region are difficult of removal, as they readily crumble at the touch, so that some process of hardening had to be employed to preserve them permanently. To this fact more than to any other cause, has been due MAEYLAND GEOLOGICAL SUKYEY 17 the small size of the collections of Eocene specimens found in the various museums of the countr}', as compared vdth the collections of Neocene forms from the same area. The forms figured and described in this report have come, with scarcely an exception, from the collections of the United States National Museum, the Academy of Natural Sciences of Philadelphia, the Johns Hopkins University, and the Maryland Geo- logical Survey. The Museum of the Academy of Natural Sciences of Philadelphia contains Dr. Conrad’s types, which have been most im- portant in definitely determining the species hitherto described. The State Geological Survey desires to express its thanks for the aid which has been rendered by the several experts who have contributed to this volume; also to the U. S. Geological Survey which has generously allowed the use of many of its plates and drawings, which have materially reduced the expenses of publication; and to Professor G. D. Harris for the loan of several drawings. Many important suggestions have also been received from Dr. W. H. Dali of the U. S. Geological Survey, Professor H. A. Pilsbry of the Philadelphia Academy of Natural Sciences and Mr. C. W. Johnson of the Wagner Free Institute of Science. They have examined many of the determinations of fossils, and have thus materially contributed to the accuracy of the report. Thanks are also due to the artists Mr. J. C. McConnell of the U. S. Army-Medical Museum, Mr. H. C. Hunter of the U. S. Geological Sur- vey and Mr. F. von Person for the beautiful drawings with which the report is illustrated. 2 THE EOCENE DEPOSITS OF MARYLAND BY WILLIAM BULLOCK CLARK AND GEORGE CURTIS MARTIN MARYLAND GEOLOGICAL SURVEY EOCENE, PLATE I I * Fossil Localities NOTE: The Nanjemoy formation is divided into the Wood- stock member which consists of argillaceotis greensands, and into the Potapaco member which is composed of argillaceous sands above and clays below. The Aquia formation is divided into the Paspo- tansa member which consists of ledges of greensand marls under- lain by greensands, and the Piscataway member which is composed of inter stratified layers of indurated greensand marls and incoherent greensands. THE EOCENE DEPOSITS OE MARYLAND BY William Bullock Clark and George Curtis Martin Intkoduction. Maryland, as an important division of the Atlantic border region, comprises in its geology and mineral resources mnch that is typical of the entire province. No discussion of Maryland geology, therefore, can be regarded as complete that does not at the same time take into con- sideration the formations of immediately adjacent states. Mnch may be learned in this way that will be of advantage in interpreting our own geology, since geological deposits are not limited by political boundaries. Maryland, together with Delaware and Virginia, forms what has with propriety been termed the Middle Atlantic Slope, and, as described in the earlier volumes of the Survey, has been divided into the Coastal Plain, the Piedmont Plateau, and the Appalachian Kegion. The pres- ent report is confined to a consideration of only a part of the first of these divisions. Much interest has been manifested in the Coastal Plain geology and paleontology of the Middle Atlantic Slope since the early days of geo- logical investigation in this country. Many of the most potent illus- trations of the geologists of the early part of the century were drawn from this region, and although the relations of the deposits were not altogether comprehended, yet the recorded observations show an appre- ciation of many of the more difficult problems involved. Later, as the complicated geological history of the Coastal Plain became better known, it was recognized that, if a full understanding of any single formation was to be gained, it was necessary to study carefully not only its litho- logical and paleontological characteristics but also its relationship to 22 THE EOCENE DEPOSITS OF MAEYLAND the other members of the series. It was seen that only by an under- standing of the broad conditions affecting the whole district could the strata of any one formation be properly interpreted. Eecognizing this fact, the writers present in later pages a brief discussion of the general relations of the strata composing the Coastal Plain in the Middle At- lantic Slope. The fuller discussions will be found in the later volumes dealing with these formations. When we come to consider that assemblage of deposits (Eocene and Neocene) early separated as the Tertiary, we find that it is divisible into several distinct formations. Even at a relatively early date an older and a younger Tertiary were already established, the former being corre- lated with the Eocene of England and the European continent. At- tempts were made then and later to find its exact equivalent in one or another of the already established local formations of the English or continental series, but with very unsatisfactory results. After the American Eocene strata had received somewhat detailed examination in the various sections of the country and local divisions had been established, attempts were made from time to time to deter- mine their equivalency. By common consent the diversified and exten- sive deposits of the Gulf area came to be regarded as the type for the eastern border region, and the various Eocene deposits of the Atlantic Coast States were assigned to positions in this series. Some authors, recognizing the presence of a few identical species, have referred the strata now under consideration to a single minor division in the scale, while others have regarded the Maryland-AGrginia deposits as repre- senting a larger portion of the Gulf series. After a careful consideration of both the paleontological and the geological data, the writers deem the latter conclusion the only tenable one. Attention has been devoted in the past too exclusively to supposed faunal similarities, upon the most insufficient knowledge of the forms, and too little to the character of the sedimentation. Important as the former are when the fauna has been fully investigated, and the writers would be far from disparaging that importance, yet the widely different physical conditions surrounding the accumulation of the deposits in the two areas must at the same time be regarded. Change in a fauna is MAE'S LAXD GEOLOGICAL SURVEA' 23 not to be measured by tlie time standard alone, but also by the condi- tions of life, whether constant or variable, to which the forms may be subjected. Persistent conditions must of necessity have less effect than those which are changing. A satisfactory correlation of the strata in districts so widely separated as the Middle Atlantic Coastal Plain and the Gulf Region can be attained only by a proper appreciation of the bearing of these factors on faunal development. In the Middle Atlantic Slope the relatively homogeneous nature of the Eocene deposits is a characteristic feature, indicating that through- out the period of deposition the conditions were undisturbed by import- ant physical changes. The fact that the deposits are made up largely of secondary materials shows in a general way that their accumulation took place near a coast reached by few large sediment-bearing rivers, and that at the same time the place of deposition was sufficiently removed from the coast line to be unaffected by shore conditions. In* the Gulf Region, on the other hand, deposition was more rapid, since a great quantity of detrital material was brought to the sea by the large streams draining the interior of the continent. The bearing of these different physical conditions upon the interpretation of the two areas and the correlation of their deposits will be fully considered in the body of the report. The materials of the Eocene of the Middle Atlantic Slope, which are so largely glauconitic, are of no little interest in themselves outside of their bearing ujion the questions of correlation, since few areas afford such extensive deposits of greensand. On that account alone they de- serve special consideration, and a chapter will be devoted to this phase of the subject. The description of new species of fossils is of little scientific impor- tance to the geologist unless the object is something other than the mere multiplication of new forms, which has too often been the case in such investigations. AVhen, however, the work has in view the fullest possible representation of a fauna or the clearing up of doubtful points in the synonymy of already described species, as well as a more complete knowledge of their geological and geographical ranges, it becomes of the very greatest value, since one whole class of important criteria for 24 THE EOCENE DEPOSITS OF MAEYLAND the interpretation of the strata is thus made accessible. The present report includes the results of such an exhaustive study of the fauna of the Eocene of Maryland, together with a critical review of the species described by previous authors, as well as the description of a large num- ber of new forms. It is believed that a much more accurate idea of the faunal characteristics, as well as of the physical conditions prevailing during the Eocene period on the Middle Atlantic Coast, will result from the methods pursued in this investigation. Certainly the data for the comparison of the fauna with those of other areas will be greatly aug- mented. Histoeical Eeyiew.^ On account of its extensive waterways and the ready access thereby gained, the Atlantic Coastal Plain was early visited for purposes of geo- logical investigation. At first the observations were of the most general character, no attempt being made to differentiate the deposits or even to correlate the strata as a whole with those of other districts. Among the earliest investigators of the region was Professor Peter Kalm, who was sent out in 1749 under the auspices of the Swedish Koyal Academy of Sciences to make a study of the various branches of natural history in America, and who spent considerable time in a study of the northern Coastal Plain. He was followed in 1777 by Dr. Johann David Schopf, of Germany, who visited America in order to study the geological features of the eastern portion of the continent. The importance of his observations, which mark considerable advance over those of Kalm, has not been very generally recognized by later writers, but he showed a remarkably keen insight into the geology of eastern Korth America, which was lacking on the part of some of his successors. The first attempt to correlate the deposits of the eastern United States with the geological column then established in Europe was made by William Maclure, in 1809, in his Observations upon the Geology of the 1 Both in this and in the subsequent chapter, comprising the Bibliography, refer- ences are made to articles and books dealing also with the Eocene of Delaware and Virginia since the deposits are embraced in the same geologic province with those of Maryland. MARYLAND GEOLOGICAL SURVEY^ 25 United States. In this publication the coastal deposits of the Middle Atlantic Slope are collectively referred to the Alluvial formation/’ the fourth of the main divisions of geological strata originally proposed hy Werner. The work was subsequently revised and enlarged, appearing in book form in 1817.* In 1820 II. H. Hayden, of Baltimore, published a volume of Geological Essays, in which he attempted to explain the great accumulation of alluvial deposits” in the Atlantic Coastal Plain. In this volume the stratigraphy of the region is described in much greater detail than by his predecessors, and reference is made to the wide distribution of fossil shells and vertebrate remains, many localities being cited. A volume of the same character, so far as it relates to the geology, was published in 1822 by Parker Cleaveland, entitled an Elementary Trea- tise on Mineralogy and Geology, in which, on page 785, under remarks on the Geology of the United States explanatory of the subjoined geological map,” the limits and the lithological character of the allu- vial deposits ” are described in general terms. By far the most important contribution to the stratigraphy of the Atlantic Coastal Plain that had up to that time appeared was made by Professor John Finch, in a “ Geological essay on the Tertiary formations in America,” in the American Journal of Science and Arts for 1824. This was the first attempt at a division of the deposits of the Coastal Plain and their correlation upon scientific grounds; and although thus early in the history of the subject detailed comparisons (which are always unsatisfactory) were made, yet the knowledge of the formations was materially advanced. The author says: In America an immense tract of country, extending from Long Island to the Sea of Mexico, and from 30 to 200 miles in width, is called an alluvial formation. From an examination of fossils brought from that quarter of the United States, from a personal inspection of some of its strata, and the perusal of most of the publications which bear a reference to it, I wish to suggest that what is termed the alluvial for- mation in the geological maps of Messrs. Maclure and Cleaveland is identical and con- temporaneous with the newer Secondary and Tertiary formations of France, England, Spain, Germany, Italy, Hungary, Poland, Iceland, Egypt and Ilindostan. The deposits of various portions of the Middle Atlantic Slope are considered in greater or less detail, and correlations with the strata of 26 THE EOCENE DEPOSITS OF MAKYLAND other portions of the Coastal Plain and with Europe are attempted.. The author states in short that — Many more instances might be advanced to establish the identity of what has been called the alluvial district in America with the Tertiary formation of England and the continent of Europe. The fossil shells from the various beds would not, perhaps, be exactly like those of Europe, but a sufficient number would be found so to establish their relation and order of succession. During the year 1825 Jer. Van Eensselaer delivered in the New York Athenaeum a course of geological lectures that were subsequently pub- lished in book form. The author adopted the classification proposed by Einclq confining his descriptions, however, more particularly to the formations of the northern Coastal Plain. The American Journal of Science for 1826 contains a communication by James Pierce On the shell-marl region of the eastern parts of Vir- ginia and Maryland,’’ in which reference is made to the sections on the James and Potomac rivers and to the shell rock ” at Upper Marlboro. A few years later (1828) Professor Lardner Vanuxem, through his friend, Dr. S. G. Morton, presented the criteria for a more complete and definite recognition of the several members of the coastal series, and described both the Cretaceous and Tertiary formations. In this article an attempt is made to define more accurately the limits of the Tertiary. The author states that much that had been designated by that name properly belongs to other formations. Up to the year 1830 all investigations of the stratigraphy of the Ter- tiary had been carried on in the main independently of a study of the fossils. Generic identity had been cited as ground for correlation, and although this aided largely in determining the limits of the Tertiary itself, further subdivisions were impracticable. The publication of Conrad’s article On the geology and organic re- mains of a part of the peninsula of Maryland,” with an appendix con- taining descriptions of new species of fossil shells, inaugurated a new era in the investigation of the Coastal Plain strata. It is true that Say had already described several Tertiary species, including the common Ostrea compressirosira of the Eocene of the Middle Atlantic Slope, but, as stated in Conrad’s paper, he did not draw any geological inferences MARYLAND GEOLOGICAL SURVEY 27 from the organic remains examined.” Conrad from the first applied the paleontological evidence he had acquired to an interpretation of the stratigraphy; and, although many of his conclusions were erroneous, the knowledge of the geology of the Coastal Plain was very materially ad- vanced hy his work. In this first paper such well-known early Ter- tiary forms as Turritella mortoni, CucuUaea gigantea, and Crassatella alaeformis are figured and described, while the presence of Venericardia planicosta Lamarck is also noted. By the use of the data afforded hy these investigations the strata at Fort Washington, were correlated with the London Clay of England. In 1832 Conrad began the publication (in parts) of an important work entitled Fossil shells of the Tertiary formations of North America.” This and its companion volume upon the “ Middle Ter- tiary,” commenced some years later, must he regarded as the basis of all later work upon American Tertiary paleontology. In the earlier publi- cation Conrad regarded the deposits in the vicinity of Fort Washington, as Middle Tertiary,” and correlated them with the London Clay and Calcaire grassier of Europe, and the Claiborne beds of Alabama. Before the completion of Conrad^s first work above mentioned Lea published his Contributions to geology,” in which a large number of Eocene fossils are described and the stratigraphy of the Tertiary of the Atlantic Coastal Plain is discussed. In this work the term Eocene is first applied to the American Lower Tertiary deposits, although the general position of the deposits had already been recognized hy Conrad. The latter, however, in 1834, in his Observations on the Tertiary and more recent formations of a portion of the Southern States,” employs the term Eocene for the Eort Washington deposits, although he there regards them as younger than the Claiborne beds, and even suggests their Miocene age. During the same year Professor William B. Eogers made his first con- tribution to the Eocene geology of Virginia, and although this article contained little of real importance, it is of interest as being the first of a series of important publications upon the geology of Virginia. Dr. S. G. Morton, whose investigations were chiefly confined to the Cretaceous, gives in his Synopsis, etc.,” published at this time, a 28 THE EOCENE DEPOSITS OF MARYLAND Catalogue of the fossil shells of the Tertiary formations of the United States/^ in which many of the Middle Atlantic Slope forms are included. During the year 1835 several important contributions were made to the geology of the Atlantic Tertiary region. Conrad published his in- vestigations upon the IMaryland-A^irginia Tertiary area, including the description of two new species of Eocene fossils. Eogers presented “Further observations on the greensand and calcareous marl of Vir- ginia, in which the lithological similarity of the beds to the greensand deposits of New Jersey is dwelt upon, although he believes that the character of the organic remains shows the strata to be Eocene. Jointly with his brother, H. D. Eogers, he presented to the Philadelphia Acad- emy of hTatural Sciences the first portion of “ Contributions to the geol- ogy of the Tertiary formations of Virginia,’’ in which several new species of Eocene fossils are described. While the investigations hitherto mentioned were being carried on privately, the three states constituting that portion of the Middle At- lantic Slope now under consideration, viz., Delaware, Maryland, and Virginia, became aroused to the importance of official geological surveys of their areas. The first to organize such a survey was Maryland, in 1833, J. T. Ducatel being appointed State Geologist. Eeports were published until 1841, but the information they contain is economic rather than strati- graphic. The Geological Survey of Virginia began operations in 1835, under William B. Eogers as State Geologist, who was thus able to continue much more systematically than hitherto his observations upon the Ter- tiary belt. The first report, for 1835, which contains a general state- ment regarding the “ Eocene marl district,” and most of the subsequent annual reports, which were continued until 1841, include more or less detailed descriptions of the Eocene deposits. Collectively they form the chief source of information regarding the Eocene stratigraphy of Virginia. The Geological Survey of Delaware was short lived. Its investiga- tions, under the direction of I. C. Booth, State Geologist, extended only over the seasons 1837 and 1838, for which years annual reports were MAEYLAXD GEOLOGICAL SUEVEY 29 published, and, in addition, a more exhaustive ‘^Memoir’’ in 1841; bnt in none of these jmblications was the Eocene recognized as such. Conrad, who actively continued his investigations, made an import- ant contribution to the Eocene of the Middle Atlantic Slope in 1842 in his Observations on a portion of the Atlantic Tertiary region, with a description of new species of organic remains.” During this year the first of Lyell’s pnblications npon the eastern Tertiary belt appeared in the Proceedings of the Geological Society of London. His conclusions were derived from personal observations, and were of special value from his wide knowledge of the Tertiary of Europe. He succeeded in explaining many points in American Tertiary stratigraphy hitherto imperfectly understood. The narrative of his first report contains the following statement: Having examined the most important Cretaceous deposits in New Jersey, Mr. Lyell proceeded in the autumn of 1841 to investigate the Tertiary strata of Virginia, the Carolinas, and Georgia, with a view to satisfy himself, first, how far the leading divisions of Tertiary strata along the Atlantic border of the United States agree in aspect and organic contents with those of Europe; and, secondly, to ascertain whether any rocks containing fossils of a character intermediate between those of the Cretaceous and the Eocene beds really exist. The conclusions at which he arrived from his extensive survey are given briefly as follows : (1) The only Tertiary formations which the author saw agree well in their geological types with the Eocene and Miocene beds of England and France; (2) he found no secondary fossils in those rocks which have been called Upper Secondary and supposed to constitute a link between the Cretaceous and Tertiary formations. The Eocene deposits upon the James Eiver, Virginia, are described in this paper. In his subsequent papers bearing upon the Eocene of the Middle Atlantic Slope the stratigraphy of the Eocene is further considered and references are made to other localities which he visited. Murchison, in his presidential address before the Geological Society of London in 1843, reviewed the results of LyelFs investigations in America and added his own interpretation of a few points. During the years immediately subsequent to LyelTs visit many im- portant articles upon the Tertiary appeared from the pens of American geologists, although the publications dealt more largely with the south- ern than the northern deposits. Conrad, however, made additional observations upon the Eocene strata of the Middle Atlantic Slope and 30 THE EOCENE DEPOSITS OE MAEYLAND described a number of new species. About this time Henry C. Lea pub- lished a Catalogue of the Tertiary Testacea of the United States/' in which the Middle Atlantic Slope forms are included. Subsequent to 1850 interest in the Tertiary geology of the Middle Atlantic Slope seems for a time to have waned, and during the next twenty-five years very few investigations were carried on within the dis- trict. In Maryland two surveys, partly of a geological but more largely of an agricultural nature, were inaugurated, the first, under James Hig- gins, producing six reports between 1850 and 1858, and the second under Philip T. Tyson, who presented two reports in 1860 and 1862. In the report for 1860 the Tertiary is described in some detail, although no attempt is made to establish the limits of its several divisions. Conrad continued, however, to carry on his investigations upon the Atlantic Tertiary belt, adding to the number of new fossil forms and publishing two catalogues of species. During the last twenty-five years, and particularly in the latter part of this period, many more contributions have been made to the geology of the Middle Atlantic Slope. Among those who have given the subject attention may be mentioned McGee, Heilprin, Darton, Uhler, Shattuck,. Bibbins, Harris and the authors of this report. To the publications of McGee we are indebted more than to any other for a general statement of Coastal Plain conditions. Although some modifications have been deemed necessary after a detailed study of the formations, the writers are impressed, from a careful examination of large portions of the area, with the general correctness of the broad principles enunciated by him. Heilprin has devoted considerable attention to Atlantic Coast paleon- tology, comparing several of the Eocene species of Maryland and Vir- ginia with European forms, and correlating the strata, as a result of these investigations, with the lower members of the English and French series. Both Darton and Uhler have studied the local relations of the Eocene deposits, the former having prepared several United States Geo- logical Survey atlas sheets of the central and southern portions of the district. Others have turned their attention from time to time to the area, and from their knowledge of other districts have aided to a greater or less MAKYLAND GEOLOGICAL SUEVEY 31 degree in interpreting the geology of the Eocene of Maryland. The articles contributed by all the various workers in this field are given in the bibliography. Bibliography. Aldrich, T. H. x^otes on Eocene Mollnsca. Bull. Amer. Pal., vol. ii, No. 8. Crassetalla declivis Heilprin and Ringicula dalli Clark are figured. Bagg, K. M. Jr. Contributions to the Eocene fauna of the Middle Atlantic Slope. Protozoa. Johns Hopkins Univ. Circ., vol. xv, 1895, p. 6. Spiroplecta clarki is described from Woodstock, Virginia. The Eocene Deposits of the Middle Atlantic Slope in Dela- ware, Maryland and Virginia. Protozoa. Bull. 141, U. S. Geol. Surv 65 % 1896, pp. 91, 92. A list of Eocene Foraminifera is given. The Tertiary and Pleistocene Foraminifera of the Middle At- lantic Slope. Bull. Amer. Pal., vol. ii, No. 10, 1898, pp. 295-348 (1-34), pis. xxi-xxiii (i-iii). Several Eocene species are figured and described. The occurrence of Cretaceous fossils in the Eocene of Mary- land. Amer. Geol., vol. xxii, 1898, pp. 370-375. The author mentions the occurrence of Terebralula liarlani and Gryphaea vesicularis in the Maryland Eocene. Bailey, J. W. htotice of some New Localities of Infusoria, Fossil and Eecent. Amer. Jour. Sci., vol. xlviii, 1845, pp. 321-343, pi. iv. Mentions occurrence of casts “ in some of the Eocene marls from Fort Washington.” On the Origin of Greensand, and its formation in the oceans of the present epoch. Amer. Jour. Sci., 2nd ser., vol. xxii, 1856, pp. 280-284. Proc. Bost. Soc. Nat. Hist., vol. v, pp. 364-368. Author again refers to “ casts ” found in Fort Washington Eocene. Bassler, Pay S. and Nickles, John M. A Synopsis of American Fossil Bryozoa. Bull. 173, U. S. Geol. Survey, 1900, p. 72. Upper Marlboro is included in the list of Eocene localities. 32 THE EOCENE DEPOSITS OF MARYLAND Booth, J. C. Memoir of the Geological Survey of the State of Dela- ware, including tlie application of the geological observations to agri- culture. Dover, 1841, 8vo, xi and 188 pp. The author gives a description of tlie Upper Secondarj^ and Tertiary formations, hut does not distinguish the Eocene. Clark, William Bullock. On three geological excursions made during the months of October and November, 1887, into the southern counties of Maryland. Johns Hopkins Univ. Circ., vol. vii, 1888, pp. 65-67. Reference is made in this article to the Eocene of Upper Marlboro and Port Tobacco. Third annual geological expedition into southern Maryland and Virginia. Ibid., vol. ix, 1890, pp. 69-71. The author describes the Eocene section of the Potomac river valley in Maryland and Virginia. Eeport of the scientific expedition into southern Maryland. Ibid., vol. X, 1891, pp. 105-109. Much of the same areas are described in this report as in the preceding paper. Correlation Papers — Eocene. Bull. 83, U. S. Geol. Survey, 1891, pp. 43-48, 80, 81, 85-87. The author gives a digest of the literature of the Eocene of the Middle Atlantic Slope, as well as a description of the deposits. Correlation is made with the lower and middle divisions of the Gulf series. Outline of the geology and physical features of Maryland. The Eocene. In Maryland, its Resources, Industries and Institutions, Baltimore, 1893, pp. 53-56. In this report the author gives a brief description of the Eocene deposits of Maryland. The climatology and physical features of Maryland. First Biennial Report Md. State Weather Service, 1894, pp. 38-39. Description of the same area as in the preceding report. Contributions to the Eocene fauna of the Middle Atlantic Slope. Johns IIoj)kins Univ. Circ., vol. xv, 1895, x^p. 3-6. This article contains a list and discussion of the Eocene species of Delaware, Mary- land and Virginia, with the description of 32 new forms. The part upon Corals is pre- pared by Vaughan, that upon Foraminifera by Bagg. The Potomac Eiver Section of the Middle Atlantic Coast Eocene. Am. Jour. Sci., 4th ser., vol. i, 1896, x^p. 365-374. A detailed section of the Botomac river section is given. MARYLAXD GEOLOGICAL SUKVEY 33 The p]ocene Deposits of the iMiddle Atlantic Slope in Dela- ware, Maryland and Virginia. Bull. 141, U. S. Geol. Survey, 1896, 167 j)p. 40 plates. A general discussion of the geological features, distribution, character and correlation of the deposits, with a description of the contained fossils. A number of new species are added. Outline of present knowledge of the Physical Features of Maryland, embracing an account of the Physiography, Geology, and Mineral Eesources. Md. Geol. Survey, vol. i, 1897, pp. 195, 196, 217. The Eocene deposits of the state are described. Collection of Eocene Fossils. Johns Hopkins Univ. Circ., vol. xviii, 1898, No. 137, p. 18. The author substitutes the name Pecten dalli for Pecten ro(jersi which was already pre-empted. Cleavelaxd, Parkek. — An elementary treatise on mineralogy and geology. Pemarks on the geology of the United States explanatory of the subjoined geological map, Boston, 1822, 785 ])]l The author defines the limits of the “ alluvial deposits ” and in general terms describes their lithological character. CoxRAD, T. A. On the geology and organic remains of a part of the peninsula of Maryland. Jour. Acad. Nat. Sci., Bhila., vol. vi, 1830, pp. 205-217. Reference is made to the deposits of Fort Washington and IMscataway, and correla- tion proposed with London Clay of England. The paper also contains original descrip- tions of Mouodonta (jlaruhda, TurriteUa mortnni, Cucullata (jUfcintca, and Craxmtella alaeformifi from this region. ^ — Fossil shells of the Tertiary formations of North America, 1832-1835, 56 pp. (including republication No. 3), 20 pis. The author regards the deposits in the vicinity of Fort Washington as “ Middle Tertiary,” and correlates them with the London Clay, Calcaire {jrosnier and Claiborne beds. He also describes Cardita planicoi^ta and TurriteUa mortoni from Piscataway. Observations on the Tertiary and more recent formations of a portion of the Southern States. Jour. Acad. Nat. Sci., Bhila., vol. vii, 1834, pp. 116-129. Mention is made of the deposits of Fort IVashington, which are considered younger than the strata at Claiborne, Ala., perhaps Miocene in age. Observations on the Tertiary Strata of the Atlantic Coast. Amer. Jour. Sci., vol. xxviii, 1835, pp. 104-111. Author states that there are no Eocene species common to the Pliocene. Observations on a portion of the Atlantic Tertiary region. Trans. Pennsylvania Geol. Soc., vol. i, 1835, pp. 335-341, pi. xiii. The deposits at Upper Marlboro and Piscataway, and City Point, Va., are considered, and Panopaea elomjata and TurriteUa humerom, from Piscataway described. 3 34 THE EOCENE DEPOSITS OF MAEYLAXD Notes on American Geology. Observations on characteristic Fossils, and upon a fall of Temperature in different geological epochs. Amer. Jour. Sci., vol. xxxv, 1839, pp. 237-251. Refers to the Eocene deposits of Upper Marlboro and Piscataway as illustrations of deposition by gentle currents. On the Silurian system, with a table of the strata and char- acteristic fossils. Observations on the Plastic Clay. Amer. Jour. Sci., vol. xxxviii, 1840, pp. 91-92. The authors discusses the relations of the Plastic Clay to the fossiliferous deposits at Piscataway, which it is regarded in some instances to overlie. Observations on a portion of the Atlantic Tertiary region, with a description of new species of organic remains. Proc. Nat. Inst. Prom. Sci., 2nd bull., 1842, pp. 171-194. The deposits of Upper Marlboro, Piscataway and Fort "Washington are referred to the Eocene or Lower Tertiary, and at the same time correlated with the London Clay, CaLcaire grassier, Claiborne beds, etc. The author also describes Ostrea seUaeformis from City Point, Va., and Pholadoniya marylandica and Pholas petrosa from Piscataway. Observations on the Eocene formations of the United States, with descriptions of species of shells, etc., occurring in it. Amer. Jour. Sci., 2nd series, vol. i, 1846, pp. 209-220, 395-405, pis. i-iv. The article contains descriptions of Pholas petrosa, Pholadomya marylandica, Pan- opaea elongata, and Crassatella alaeformis from Piscataway, and Crassatella palmula from Upper Marlboro. Observations on the Eocene formation and descriptions of one hundred and five new fossils of that period from the vicinity of Vicksburg, Mississippi. With appendix. Proc. Acad. Nat. Sci. Phila., vol. iii, 1847, pp. 280-299. The author regards the Fort Washington, Piscataway and Upper Marlboro -deposits as lower Eocene. Observations on the Eocene formation and descriptions of 105 new fossils of that period from the vicinity of Vicksburg, Miss. Appen- dix: Descriptions of new Eocene fossils in the cabinet of Lardner Vannxem. Jour. Acad. Nat. Sci., Phila., 2nd series, vol. i, 1848, pp. 128-134, pi. xiv. The author considers the Maryland and Virginia deposits as “ Lower or older Eocene ” and correlates them with the “ fossiliferous sand of Claiborne and St. Steph- ens, Ala.,” etc., chiefly from the presence of 0. seUaeformis. He also describes CyLherea subimpressa, C. lenis, C. liciata. C. eversa, and Nucula improcera from Hanover County, Va. ; Cytherea pyga from Stafford County, Va., and Nucula parilis from Upper Marlboro. Notes on Shells. Proc. Acad. Nat. Sci. Phila., vol. vi, 1853, p. 320. Cytherea lenticularis Rogers is referred to the genus Artemis of Poli. MARYLAND GEOLOGICAL SURVEY 35 Eectification of the generic names of Tertiary Fossil Shells. Proc. Acad. Nat. Sci. Phila., vol. vii, 1854, pp. 29-31. The generic names of .several Ik>cene fossils from Maryland and Virginia are changed. Xotes on shells, with descriptions of new fossil genera and species. Proc. Acad. Nat. Sci. Phila., vol. xvi, 1864, pp. 211-214, with figures. Descriptions are given in this article of Protocardia virginiana from Pamunkey River, Va., and DoniniopsiK meehii from 6 miles east of AVashington, D. C.” Catalogue of the Eocene and Oligocene Testacea of the United States. Amer. .Tour. Conch., vol. i, 1865, pp. 1-35. Among other forms the catalogue contains a list of the Eocene species of the Middle Atlantic Slope. Descriptions of new Eocene shells and references, with fig- ures, to published species. Ibid., pp. 210-212, pis. xx, xxi. The author describes Lunalia rnarylandica, but gives no locality. Check list of the invertebrate fossils of Xorth America (Eocene and Oligocene). Smithsonian ^lisc. Coll., vol. vii, 1866, art. 6, pp. 1-41. The Eocene species from the Middle Atlantic Slope are included in this list. Descriptions and illustrations of genera of shells. Proc. Acad. Nat. Sci. Phila., 1872, pp. 50-55. The author describes Latiarca idonea, but gives no locality. Dale, VC. H. Contributions to the Tertiary Fauna of Florida, etc. Trans. AVagner Free Inst. Sei., vol. iii, pts. i-v, 1890-1900, pp. 1-947. The biological and geological relations of many of the Maryland and A'irginia Eocene molluscan species are discussed. A Table of the Xorth American Tertiary Horizons correlated Avith one another and Avith those of Western Europe, Avith annotations. 18th Ann. Kept. U. S. Geol. Survey, 1898, pt. ii, pp. 325-348. The Aiaryland Eocene is briefly discussed. Dana, James D. Manual of Geology (fourth edition), 1895, p. 888. Brief reference is made to the geologj* of the Middle Atlantic Slope. Darton, X. H. ^lesozoic and Cenozoic formations of eastern Vir- ginia and Maryland. Bull. Geol. Soc. Amer., vol-. ii, 1891, pi. x, pp. 431-450. The author gives a description of the Eocene deposits of Maryland and ATrginia, and designates them the “ Pamunkey formation.” 36 THE EOCEXE DEPOSITS OF MARYLAND Outline of Cenozoic history of a portion of the Middle At- lantic Slope. Jour, of Geol., vol. ii, 1894, pp. 568-587. The physical history during the Eocene period is briefly referred to, and the relation- ship of the deposits to earlier and later formations is stated. Artesian well prospects in eastern Virginia, Maryland, and Delaware. Trans. Amer. Inst. Min. Eng., vol. xxiv, 1894, pp. 372-379. The lithological character of the strata is discussed and several deep borings are described. Fredericksburg Folio, Virginia and Maryland. U. S. Geol. Survey, Geol. Atlas, folio 13, Washington, 1894. The author describes the Eocene deposits of the area. Artesian Well Prospects in the Atlantic Coastal Plain Eegion. Bull. 138, U. S. Geol. Survey, 1896, 228 pp., 19 plates. Numerous Eocene sections are given. Nomini Folio, Maryland and Virginia. U. S. Geol. Survey, Geol. Atlas, folio 23, Washington, 1896. The author describes the Eocene deposits of the area. Ducatel, J. T. Annual reports of the geologist of Maryland from 1833 to 1841. Annapolis, 8vo. Only brief references to Eocene deposits, and those chiefly of an economic nature, are found scattered through the reports. Featherstonhaugh, G. W. Geological Eeport of an examination made in 1834 of the Elevated Country between the Missouri and Eed Eivers. Washington, 1835, 8vo, 97 pp. The author refers to the Eocene deposits of ^Maryland, especially the fossil if erous beds at Fort Washington and correlates them with “ Lyell’s Eocene.” Finch, John. Geological essay on the Tertiary formations in America. Amer. Jour. Sci., vol. vii, 1824, pp. 31-43. This article contains the first attempt at a differentiation of the “ alluvial formation ” of the Coastal Plain. The Tertiary is recognized. Finch, J. Travels in the United States of America and Canada. London, 1833, 8vo, 355 pp. The author refers to the geology at Fort Washington. Fontaine, W. M. Notes on the ]\Iesozoic strata of Virginia. Amer. Jour. Sci., 3rd series, vol. xvii, 1879, pp. 25-39. 151-157, 229-239. The relations of the Eocene to Mesozoic strata are indicated. MAEYLAXD GEOLOGICAL SURYEA" 37 The artesian well at Fort Monroe, Va. The Virginias, vol. iii, 1882, pp. 18-19. The Tertiary is regarded as haying a thickness of 800 feet. Harris, Gilbert D. Eepnhlication of ConracFs Fossil Shells of the Tertiary Formations of North America. Washington, 1893, 8vo, pp. 1-121, pis. i-xx. The repnblication of Conrad’s important monograph on Tertiary Mollusca, for many years out of print, has rendered it now available to all paleontologists. On the geological position of the Eocene deposits of Mary- land and Virginia. Ainer. Jour. Sci., 3rd series, vol. xlvii, 1894, pp. 301-304. The Eocene deposits of the Middle Atlantic Slope are correlated by the author with the Bell’s Landing substage of the Lignitie of the Gulf. The Lignitie Stage. Bull. Amer. Pal., vol. ii. No. 9, 1897, pp. 193-294 (1-102), pis. vii-xx (i-xiv), and vol. iii. No. 11, 1899, pp. 1-22, pis. i-xii. Many species found in the Maryland Eocene are described and figured. Haa'den, H. H. Geological essay, or an inquiry into some of the geological phenomena to he found in various parts of America and else- where. Baltimore, 1820, 8vo, viii, 412 pp. The general features of the “ alluvial formation ” of the Coastal Plain are desci-ibed in this volume. Heilprin, a. a comparison of the Eocene Mollusca of the sonth- eastern United States and western Europe in relation to the determina- tion of identical forms. Proc. Acad. Nat. Sci. Phila., vol. xxxi, 1879, pp. 217-225. Several forms known to occur in Maryland and Virginia are compared in this article with European species. On the stratigraphical evidence afforded by the Tertiary fos- sils of the peninsula of Maryland. Ibid., vol. xxxii, 1880, pp. 20-33. The author calls attention to the few Eocene fossils in the Maryland strata, and the marked difference between the Eocene and Miocene faunas. Note on the approximate position of the Eocene deposits of Maryland. Ibid., vol. xxxiii, 1881, pp. 444-447. The Maryland Eocene is regarded as “ nearly e Bull. Geol. Soc. Amer., vol. ii, 1891, p. 411. 58 THE EOCENE DEPOSITS OF MAKYLAND of the upper member has been shown to persist very generally through- out the area, while the beds above and below are sufficiently distinct as regards their lithologic and faunal characteristics to be distinguished readily everywhere by the geologist in the field. It is therefore evident that every interest will be subserved by the establishment of two forma- tions, and they will be thus recognized both in the text and on the accompanying map. Each of these formations also represents a well- defined paleontological stage and each is again divided into two clearly defined members or substages, and the latter again subdivided locally into zones. EOKMATIONS AND FAUNAL STAGES." The two formational units of the Eocene of Maryland are known as the Aquia foemation and the Nanjemoy foematton, names derived from localities in the Potomac valley where the deposits of each division are typically developed. Each is characterized by a well-marked fauna, representing a clearly-defined paleontological stage.^ The formations are in each instance divided into two members which represent an equal number of paleontological substages. The Aquia FOEMATION is divided into a basal Piscataway member or substage, and an overlying Paspotansa member or substage; and the ETanjemoy foema- tion is divided into a lower Potapaco member or substage and an upper Woodstock member or substage. These various divisions are shown in the following table: Group. Formations or Stages. Members or Substages. r 1 Nanjemoy. ' f Woodstock. 1 Potapaco. Pamunkey. 1 1 j Paspotansa. i Aqnia. ( 1 Piscataway. 1 In discussing tlie various divisions of the Maryland Eocene deposits a distinction is drawn between stratigraphic and paleontologic units ; the former are designated as formations and members, the latter as stages and substages. As their limits are the same the same name is employed for each. 2 The senior author in an earlier publication (U. S. G. S., Bull. 141, p. 39) divided the Pamunkey on the basis of its contained fauna into the Aquia and Woodstock stages. Later investigation has shown that the fauna from the Woodstock beds constitutes simply a substage, and that this fauna together with the fauna more lately discovered in the underlying beds, and called the Potapaco substage, comprises a larger division now termed the Nanjemoy stage and formation. MAEYLAXD GEOLOGICAL SURVEY 59 Several species have been found vdiicli are common to all the substages of the Pamnnkey. They are: Vohitilithes peirosus (Conrad). Corbula oniscus Conrad. Calyptraea aperta (Solander). Tellina virginiana Clark. Cadulus ahruptus Meyer and Aldrich. 2Iodiolus alabamensis Aldrich. Still other, forms are found in both the Aquia and Nanjemoy stages, although not recognized in all the snbstages. The following species have been found in the Piscataway, Paspotansa, and Potapaco snbstages, but are not known in the Woodstock, viz.: Tornatellaea beUa Conrad. Lunatia maryJandica Conrad. Cylichna venusta Clark. Ontrea {Gryphaeostrea) vomer (Morton). The following have been found in the Paspotansa and Potapaco sub- stages, viz.: CaJyptraphorus trinodifertis Conrad. Dentalium mississippiensis Conrad. The following form ranges from the Paspotansa through the Potapaco and Woodstock substages, viz.: Pecten choctavensis Aldrich. The following forms have been potansa and Woodstock, viz.: Myliobatis copeanus Clark. Odontaspiff cnspidata (Agassiz). Strepsidura mbscalarina Heilprin. Corbula subengonata Dali. Protocardia lenii< Conrad. found only in the Piscataway, Pas- Lucina uJileri Clark. GucuUaea gigmitea Conrad. Nodosaria bacillum Defrance. Polymorphina gibba d’Orbigny. Truncatulina ungeviana (d’Orbigny). The Aquia Formation or Stage. The Aquia formation, so-called from Aquia Creek, which enters the Potomac river from the Virginia side about fifty miles below Washing- ton, is composed chiefly of greensands and greensand marls, at times highly calcareous and less frequently argillaceous. The various litho- logical and paleontological characteristics are clearly shown in the de- tailed sections which follow. The deposits reach about 100 feet in thick- ness, gradually thickening eastward. The name Aquia was originally employed ' to embrace the faunal stage represented by Zones 2 to 9. •Johns Hopkins Univ. Circ., 1895, p. 3; Bull. 141, U. S. Geol. Survey, 1896, p. 39. 60 THE EOCENE DEPOSITS OF MARYLAND To these may be temporarily added Zone 1, which^ so far as known, is devoid of determinable fossils, although indeterminate mollnscan casts and plant remains have been found near the base of the zone. It is possible that this zone should be made an independent stage, and it is not improbable that it may represent a definitely lower Eocene horizon than the more fossiliferous beds which overlie it, but in the absence of distinctive fossils it is impossible to definitely characterize it. It may be regarded at present at least as the basal zone of the Aqnia. The Aqnia stage contains an extensive fauna. Among the forms that are found in both substages are the following: Thecachampsa sp. Thecachampsa marylandica Clark. Cy there marylandica Ulrich. Volutilithes i>p. Caricella pyruloldes (Conrad). Turritella mortoni Conrad. Turritella humerosa Conrad. Vermetus sp. Solarium sp. Scala virginiana Clark. Gibbula glandula (Conrad). Gastrochaena sp. Panopea elongata Conrad. Meretrix ovata var. pyga (Conrad). Lucina aquiana Clark. Venericardia planicosta var. regia Conrad. Crassatellites alaef ormis Conrad. Crassatellites aquiana Clark. Ostrea compressirostra Say Leda cliftonensis Clark and Martin. Trochocyaihus clarkeanns Vaughan. Eupsammia elaborata (Conrad). Nodosaria communis (d’Orbigny). Other species are restricted to one or the other of the substages and are mentioned beyond. Additional to these are the forms previously referred to as found in both divisions of the Pamunkey group. The Aquia formation has been divided into two members which are clearly separated by their contained faunas over considerable portions of Maryland and Virginia. They are known respectively as the Pis- cataway and Paspotansa members or substages. THE PISCATAWAY MEMBER OR SUBSTAGE. The Piscataway member, so-called from Piscataway Creek which empties into the Potomac river on the Maryland bank about ten miles below the city of Washington, is characterized by greensands and green- sand marls, the lower beds often quite argillaceous. Two well-marked and rather persistent layers of indurated marl characterize the upper beds in the Potomac region. The Piscataway member generally ex- ceeds 50 feet in thickness. MARYLAND GEOLOGICAL SURVEY G1 The PiscalaM’av substage is limited to Zones 1 to T. The fossils restricted to this horizon are: Xiphias radiata Clark. The various zones of this division in the Potomac region are charac- terized as follows: Zone 1. — The thickness of the Eocene deposits beneath the lowest beds holding the typical Aqnia fauna has been variously estimated up to 60 feet. Some exposures are seen in the ravines to the west of the bluff, but no complete sequence of the beds has been found. xA.t some points the strata, scarcely exceed 10 feet, and at Glymont the beds are only 8 feet in thickness. They, hov'evei, gradually increase in thickness sea- ward; The almost entire absence of fossils renders the faunal relations obscure. The poorA preserved animal and plant remains are of prac- tically no value, and provisionally this bed is left as an indeterminate basal zone of the Aqnia. The materials are greensands, frequently quite argillaceous and vuth a basal pebble lied overlying the Cretaceous at some points. Zone 2. — This zone is characteristically developed both at the base of the Aqnia Creek section and also on the opposite liank of the Potomac river at Glymont. The beds are from 12 to 20 feet in thickpess, and entirely disappear below the M’ater-line a little beyond the middle of the Aqnia Creek Iduff. The dark greensand of udiich the zone is mainly composed is packed with the sliells of Crassatellites alaeformis and Dosiniopsis leiiticularis, viiile Tnrritella mortoni, T. Immerosa, Crassa- tellites aquiana, Meretrix orata var. pijga, Cucullaea gigantea, and Ostrea compressirostra also occur. Zone 3. — The limestone ledge composing this bed is much less per- sistent than in the overlying limestones. Zone 5, and at times it nearly or quite disappears. It is from 2 to 3 feet in thickness, highly glau- Thecachampm aericodon (:•*) Cope. Thecachampaa contnaov Cope. End antes sp. Trionyx viryiniaua Clark. Synechodas chirkii Eastman. Odontaspis rnacrota (Agassiz). Odontaspis elegans (Agassiz). Odotus obliqiiHs (Agassiz). Sphy nia prisca Agassiz. Tndida sp. Phenacoinya petrosa (Conrad). Pholadomya marylandica Conrad. Lithophaga marylandica Clark and Martin. Ostrea compressirostra var. aJepidota Dali. Gryphaea vesicnlaris Lamarck. Terehratula harlani Morton. Textalaria suhangulata d’Orbigny. Vaginulina Jegumen (Linne). 62 THE EOCENE DEPOSITS OF MARYLAND conitic, and of dark color^ and is filled with shells or, more commonly, casts of shells, among which the forms of Zone 2 are conspicuous, together with Ostrea compressirostra and Turritella mortoni in larger numbers than in the lower beds. Zone Jf . — This zone is composed of a highly typical greensand, con- taining in the main the forms mentioned above as occurring in zones 2 and 3. It is from 7 to 9 feet in thickness. Zone 5 . — This limestone bed is very persistent and forms a conspicu- ous ledge about 2 feet in thickness, along the face of the Aquia Creek bluff until it passes below tide-water near its eastern extremity. In addition to the species already mentioned as characteristic for Zones 2 to 4, which still remain common forms, there are two highly typical species, viz.: Plioladomya marylandica and Phenacomya petrosa, as well as two or three gasteropods, Tudicla sp., Caricella sp., which from the fact that they have only been found in the form of casts cannot be further identified. Zone 6 . — This thin layer, generally about 1 foot in thickness, of dark characteristic greensand, is packed with the common forms of the pre- vious beds. It thickens somewhat to the eastward along the face of the bluff, and near Marlboro Point contains, among other forms, several species of corals, including Eupsammia elaborata, Turbinolia acuticos- tata, and Trocliocyatlius clarTceanus. Zone 7. — The bed of greensand overlying the preceding- layer is really a continuation of it, although the fossils are few in number and much broken. Fragments of the common forms of previous beds are found. This bed is about 7 feet thick. It is barely possible that this stratum of worn and broken shells represents an unconformity between the Pis- cataway and Paspotansa members. Of this, however, there is no positive evidence as yet, and we can only call attention to the fact that there are physical indications of more disturbed conditions of sedimentation than are usual in these formations at the very point where the faunal change occurs. THE PASPOTANSA MEMBER OR SUBSTAGE. The Paspotansa member, so-called from Paspotansa Creek, which enters the Potomac river from the Virginia bank, a mile below Potomac MARYLAXD GEOLOGICAL SURVEY 63 Creek, is composed of a thick bed of greensand, overlain by thick-bedded, indurated layers of greensand marl. It is generally somewhat under 50 feet in thickness. The Paspotansa substage includes Zones 8 and 9. The following fossils are restricted to this suhstage: Bijthoeypris subaequata Ulricli* Bythocypris parilis Ulrich. Cytherella tnm'Iboroensis Ulrich. Cytherella submarginata Ulrich. Cythereis basderi Ulrich. Pleurotoma harrisi Clark. Plenrotoma potonuicensis Clark and Martin. Pleurotoma ducateli Clark and Martin. Pleurotoma childreni Lea. Pleurotoma piscatavensis Clark and Martin. Plexirotoma tysoni Clark and Martin. Cancellaria graciloides Aldrich var. Cayicellaria sp. Cancellaria potomacenMn Clark and Martin. Mitra marylandica Clark. Mitra pomonkensis Clark and Martin. Latirus marylandicus Clark and Martin. Fusus subtenuis Heilprin. Trophon sublevis Harris. Melongena potomacensis Clark and Martin. Tudicla marylandica Clark and Martin. Metula marylandica Clark and Martin. Chrysodomus engonatus (Heilprin). Pseudoliva sp. Tritonium showalteri (Conrad). Fusoficula juvenis (Whitfield). Morio brevidentata (Aldrich). Calyptraphorus jacksotii Clark. Aporrhais potomacensis Clark and Martin. Litiopa marylandica Clark and Martin. Scala potomacensis Clark and Martin. Scala sessilis Conrad. Scala carinata Lea. Turbonilla potomacensis Clark and Martin. Odostomia trapaquara (Harris). Niso umbilicata (Lea). Calliostoma sp. Fissuridea marylandica Clark and Martin. The two zones recognized in the follows: Dlplodonta marlboroensis Clark and Martin. Crassatellites alia (Conrad). {?) Astarte marylandica Clark. Coralliophaga brya7ii Clark. Pecten sp. Platidia marylandica Clark and Martin. Discosparsa varians Ulrich. Fascipora subramosa Ulrich. Reticulipora dichomata Gahb and Horn. Cavaria dumosa Ulrich. Heteropora tecta Ulrich. Membranipora rimulata Ulrich. Alembranipora spiculosa Ulrich. Jfembra7tipora angusta Ulrich. Biflustra to7'ta Gabb and Horn. Eschara digitata Gabb and Horn. L7i7i7ilites reversa Ulrich. Cribrilina modesta Ulrich. Ci'ibrilina crassula Ulrich. Lepralia S7ibpla7ia Ulrich. Lepralia labiosa Ulrich. Mucronella aspera Gabb and Horn. Parac7jathus ma7'ylandicus Vaughan. Bala7ioplx7jllia desmophyllum Milne-Ed- wards and Haime. Texttdai'ia gramc7i d’Orbigny. TexUilaria sagittula Defrance. Fodosaria consorbrina var. emaciata Reuss. Nodosaria sandbei'geri (Reuss). Fodosaria obliqua (Linne). Margin ula costata (Batsch). Cristellaria gibba (d’Orbigny). C7'istella7'ia rotatula (Lamarck). Poly7no7'phina lactea (Walter and Jacob). £Hscorbi7ia tm'bo (d’Orbigny). Anomalina amrnonoides (Reuss). Anomalina grosserugosa (Giimbel). Potomac area are characterized as 64 THE EOCENE DEPOSITS OF MAKYLAND Zone 8 . — The highly characteristic greensands and greensand marls of the preceding zones are succeeded in the Potomac sections hy a zone, some 30 feet in thickness, in which the grains of glauconite have been extensively weathered when exposed, giving the strata, where outcrops are found, a greenish-gray appearance, which changes to a reddish- hrown in the upper layers. Several irregular hands packed with Turri- tella mortoni are present in both the Aquia Creek and Potomac Creek sections, while associated with that species at both localities are Turritella humerosa, Cucullaea gigantea, Crassatellites alaeformis, Ostrea compressi- rostra, and many other forms. The upper portions of this bed have afforded most of the species obtained from the Potomac Creek bluff. Zone 9 . — The thick-bedded limestone layers which compose this zone are almost exclusively made up of the shells of Turritella mortoni, form- ing a Turritella rock. (Plate III, Fig. 2.) Between the indurated layers are interstratified layers of unconsolidated and much weathered green- sand, which contain few fossils of any description. G-reat masses of this Turritella rock strew the shore at the base of both the Aquia Creek and Potomac Creek bluff's. The bed is about 10 feet thick in the Aquia Creek bluff, but reaches 17 feet at Potomac Creek. At the latter locality it consists of five feet of limestone at the base, followed by five feet of greensand, two feet of limestone, two feet of greensand, two feet of limestone and one foot of yellowish greensand. The fauna of Zone 9 is evidently identical with that of Zone 8. The Nanjemoy Formation or Stage. The FTanjemoy formation, so-called from N'anjemoy Creek, which enters the Potomac river from the Maryland side in Charles county, just below Maryland Point, is composed of greensand, often highly argil- laceous, and less frequently calcareous than the lower beds, and with here and there layers containing abundant crystals and crystalline masses of gypsum. The thickness of the deposits is about 125 feet. The Nanjemoy stage comprises Zones 10 to 17. The following fossils are found in both substages: Meretrix ovata var. ovata (Rog'ers). Lucina dartoni Clark. Lncina wlntei Clark. Venericardia potapacoemis Clark & Martin. Ostrea sellaeformis Conrad. Lcd<( improcera (Conrad). Leda potomacensis Clark and Martin. Lcda tysoni Clark and Martin. Xncula potomacensis Clark and Martin. MARYLAND GEOLOGICAL SURVEY EOCENE, PLATE V THICKNESS IN FEET ZONE Greensand, with Ostrea sellaeformis, Meretrix subimpressa, Venericardia poiapacoensis, etc. so Greensand, with few fossils, chiefly Venericardia potapa- coensis, - 4o Greenish-p:rey argillaceous sand with inconstant indurated layer at top and with many typical fossils. Greenish-gray argillaceous sand, with bands of gypsum crystals, - Light-gray greensand, with Venericardia potapacoensis. Greenish-gray argillaceous sand, Indurated argillaceous greensand, Argillaceous greensand with clay bed at base, Interstratified indurated layers and greensands with many Turritella morioni, i 7 Light greenish-gray greensand, with Turritella mortoni^ CucuUaea gigantea, Crassatellitesalaeformis, Ostrea com- pressirostra, etc., Greensand, with fragments of shells of lower beds. Greensand, with corals, Ind. greensand, vf\t\xPholadomyamarglandica,& Phenacomy a petrosa. Greensand, Indurated greensand, Dark greensand with many fossils, including Dosiniopsis lenticular is, Meretrix ovata var.pyga, Crassatellites alae- forrnis, and Ostrea compressirostra, i Greensand, at times argillaceous. Woodstock Member Paspotansa Member Piscataway Member GENERAL COLUMNAR SECTION OF EOCENE STRATA IN MARYLAND Aquia Formation Nanjemoy Formation MARYLAND GEOLOGICAL SURVEY 65 Other species are restricted to one or the other of the substages of the Nanjemoy and are mentioned beyond. x\dditional to these are the forms previously referred to as found in both divisions of the Pamunkey group. THE POTAPACO MEMBER OR SUBSTAGE, The Potapaco member, so-called from the early name of Port Tobacco Creek, which is a corruption of the word Potapaco found on the Smith and other early maps, is composed of greensand, often very argillaceous and at times gypseous. The clayey character of the member, especially in the lower bed, is in marked contrast to the more highly glauconitic nature of the Aquia formation. The thickness of the member is about 60 to 65 feet. The Potapaco substage embraces Zones 10 to 15. The following species are restricted in range to it: Cypraea smithi Aldrich. Teriploma sp. Solen lisbonensin Aldrich. Ceriopora micropora Goldfuss. (?) Lucina astartif ormis Aldrich. The following zones constitute the subdivisions of the Potapaco in the Potomac area, some of which can be recognized over wide areas: Zone 10. — The greenish-gray sand which overlies the Turritella rock is more argillaceous than the underlying or overlying beds of the Eocene. The glauconite grains have been much weathered and nearly all trace of the shell substance has been removed from the few forms recognized. To the northeast of the Potomac area, throughout the central portion of Southern Maryland, this bed becomes a well-defined clay, as at Upper Marlboro, and has been referred to as the Marlboro clay. The casts found at the Potomac Creek bluff are chiefly those of a Meretrix, prob- ably Meretrix ovata var. ovata. An indurated layer, near the middle of the zone, contains Calyptraphorus trinodiferus ; below this is the repre- sentative of the red clay which occurs typically about Upper Marlboro. No fossils were observed at the Aquia Creek bluff. The bed is about 25 feet in thickness. Zone 11. — This zone is composed of a thin, indurated layer of argil- laceous greensand, 1 to 2 feet in thickness. It is well developed at the Potomac Creek bluff, where it contains Venericardia potapacoensis, and is the lowest horizon at which this species has been found. 5 66 THE EOCENE DEPOSITS OF MARYLAND Zone 12. — A greenish-gray argillaceous sand, containing few nn- weathered grains of greensand. No fossils have been found in it. The bed is 8 or 9 feet thick. Zo7ie 13. — This bed consists of a light-gray glauconitic sand, generally somewhat weathered. It is crowded with shells of Venericardia potapa- coensis, and also contains Tornatellaea bella, Cadulus dbruptus, etc. It is 3 feet in thickness. Zone !!{-. — Overlying the Venericardia layer is a bed of greenish-gray argillaceous sand, some 4 to 6 feet in thickness, that contains a great number of bands filled with gypsnm crystals. No fossils were observed. Zone 15. — This bed consists of greenish -gray argillaceons sand, in which the glauconite grains have often been extensively weathered. The bed has a thickness of 12 to 25 feet. At various localities in Charles county, notably about Port Tobacco and at the headwaters of Nanjemoy Creek, this zone contains a fauna that is quite distinct from either the Aquia or Woodstock faunas. It is an unweathered greensand, and very argillaceous at these localities. The top of the bed is marked by a well-developed layer of concretions. This layer passes below water-level about 2J miles above the mouth of Popes Creek, and is to be seen about six feet above the base of the bluff at Woodstock. THE WOODSTOCK MEMBER OR SUBSTAGE. The Woodstock member, so-called from Woodstock, which is an old estate situated a short distance above Mathias Point on the Virginia bank of the Potomac, is characterized by fine, homogeneous greensands- and greensand marls, that are less argillaceous than the underlying Potapaco beds. The member has a thickness of 50 to 60 feet. The Woodstock substage embraces Zones 16 and 17 and contains the ’ following species in addition to those previously mentioned as ranging throughout the Nanjemoy, viz.: Carcharodon auricnlalm (Blainville). Gahocerdo latidens Agassiz. Olivula sp. LeviftiHus traheatns (?) Conrad. Levifnsus trabeatns (?) var. Pyrnla penita Conrad, var. Ptjrula sp. {?) Leda par ills Conrad var. Spiroplecta clarki Bagg. Nodomria affinis (d’OrbignjO. Cristellaria radiata Borneman. Polymorphina austriaca (d’Orbigny). Polymorphina elegantissima Parker & Jones. Polymorphina praelonga Terquem. MARYLAND GEOLOGICAL SURVEY 67 Turritella potomacensis Clark and Martin. GJohigerina huUoides d’Orbigny. Dentalium minntistriatum Gabb. Discorhina hertheloti (d'Orbigny). Meretrix lenis (Conrad). PulvinuUna schreibersii (d’Orbigny). (.^) Jleretrix subimpressa (Conrad). Xonio7iina affinis Reuss. (.^) Lucina astartif ormis Aldrich. Amphistegina lessouii d’Orbigny. Venericardia marylandica Clark & Martin. Cmpolithns mcn'yJandiciifi Hollick. 2Iodiolus marylandicus Clark and Martin. Carpolithus i7iarylandicus vcn\ r7tgosns Leda parva {Rogers). Hollick. The two zones comprising the Woodstock in the Potomac area are characterized as follows: Zone 16. — In this zone haA^e been placed the strata intervening he- ttveen the upper layers of the Potomac Creek section and the base of the Popes Creek section. The deposits are estimated to reach about 40 feet in thickness, and are chiefly greensands and greensand marls. They appear in an unfossiliferous condition in some of the raAunes to the Avest of the Woodstock area, and along the shores Avhere they contain a few fossils of common Woodstock species. Zone 17. — The highest beds at AYoodstock, and the Popes Creek strata, are grouped together in this zone. The materials are very homo- geneous, although several inconstant indurated layers appear. The thickness of this zone is about 20 feet. A thin bed of Ostrea sellaef ormis Avas observed in the lower part of the zone, although evidently not ahvays at the same horizon. OtherAvise, so far as ohserA^ed, the fossils are the same in the several parts of the tAvo sections. The most common forms are Protocardia lenis, Glycymeris idoneus, Meretrix subimpressa, Corbula subengonata, Corbula oniscus, Leda cult elli for mis, Pecten dalli, Leda improcera, Leda parva, Nucula potomacensis, Lucina dardoni, Lucina ulderi, Lucina wliitei, and Ringicula dalli. LOCAL SECTIONS. The formations and faunal stages previously described are based on the numerous local sections found scattered throughout the Eocene area of Maryland. The most numerous and complete series of sections is found in the valley of the Potomac river, hut other and highly im- portant sections are found to the northAvard nearly to the DelaAvare line. Potomac River Section. The most complete section of the Eocene deposits of the Middle Atlantic Slope is found in the valley of the Potomac river hetAveen Aquia 68 THE EOCENE DEPOSITS OF MAKYLAND Creek, Stafford county, Va., and Popes Creek, Charles connty, Md. Throughont this distance the bluffs afford a nearly complete sequence of the several beds of the formations, while the fossils are numerous and well-preserved. The full Potomac Eocene series is given in both generalized and local columnar sections on Plates V and YI. The former is made up chiefly from the local sections afforded by the bluffs at Glymont, Aquia Creek, Potomac Creek, Nanjemoy Creek, Woodstock, and Popes Creek, but con- tains additional data obtained at a few points inland. The local sections are presented in columnar form on Plate YI, and the numbering corresponds with that given at the head of the descrip- tions of the sections which follow. The numbering of the zones in the general section is the same as that in the local sections. The unnum- bered zones are pre- or post-Eocene, as the case may be. Pleistocene. I. Section at Glymont^ north of wharf and ravine. Gravel and loam Feet. 20 Eocene. r Light green glauconitic sand, underlain by argillaceous sand, with few fossils (Zone 4) Indurated greensand (Zone 3) Greenish marl with numerous fossils including Ostrea com- pressirostra, Crassatellites alaeformis, Turritella rnortoni.^ Dosinopsis lenticular is Meretrix ovata var. pyga., etc. (Zone 2) ! Argillaceous glauconitic sand for the most part without fossils, but containing indeterminate plant remains and molluscan casts at the base (Zone 1) 10 1 21 8 Cretaceous. Variegated clays of the Potomac group, 20 Total 80 II. Section two miles up Aquia Creek. Feet. Pleistocene. Gravel and sand Eocene. , f I Indurated greensand (Zone 3) ^ j Greensand with characteristic fossils (Zone 2) I Argillaceous sand more or less glauconitic without fossils ^ I (Zone 1) PL 1 15 18 Total 41 MARY EOCENE, PLATE VI :ac valley MARYLAND GEOLOGICAL SURVEY EOCENE, PLATE VI LEGEND ||£S Nanjemoy Formation I , “i Aqula Formation DETAILED COLUMNAR SECTIONS OF EOCENE STRATA IN THE POTOMAC VALLEY MARYLAND GEOLOGICAL SURVEY 69 Pleistocene. Eocene. <5 III. Section of western portion of bluff at Aquia Creek. Feet. Fine sand, liglit-yellow in color, witli white clay near the base 26 r Fine sand, of light-greenish color, containing a few glau- conitic grains (Zone 10) Thick-bedded, arenaceous, and glauconitic limestone inter- stratifled with unconsolidated layers of partially weathered greensand, the indurated layers largely filled with the shells of Turritella mortoni (Zone 9) Fine sand, of gray or green color, containing several irregular bands of Turritella mortoni., also T. humerosa., Cucullaea gigantea., Crassatellites alaeformis and Ostrea com- pressirostra (Zone 8) 10 10 30 Oj Dark-colored greensand, chiefly filled with broken shells of Meretrix ovata var. pyga and Crassatellites alaeformis (Zone 7) 7 Ditto, with same shells in whole condition (Zone 6) 1 Indurated layer of light-colored greensand filled with Turritella mortoni., T. humerosa., Crassatellites alaeformis., Dosiniopsis lenticularis, Meretrix ovata var. pyga, Panopea elongata, Pholadomya marylatidica (Zone 5) 2 Greensand marl containing same forms (Zone 4) 8 Indurated layer of dark-colored greensand with Crassatellites alaeformis, Meretrix ovata var. pyga, Dosiniopsis leiiticularis, and Ostrea compressirostra (Zone 3) 2 Greensand marl with Dosiniopsis lenticularis, Meretrix ovata var. pyga and Crassatellites alaeformis (Zone 2) 16 Total 112 IV. Section of center of bluff at Potomac Creek. Feet. Pleistocene. Fine yellowish sand containing red and brown bands 15 Neocene. White gritty clay, with Miocene fossils at base 5 Eocene. ii Greenish-gray argillaceous sand, slightly glauconitic (Zone 15) 38 Argillaceous sand containing bands of selenite crystals (Zone 14) 4 Light-gray glauconitic sand with Venericardia potapacoensis (Zone 13) 3 Greenish-gray argillaceous sand (Zone 12) 8 Indurated greensand with Venericardia potapacoensis (Zone 11) 1 Greenish-gray argillaceous sand, glauconitic, with casts of Meretrix (Zone 10) 25 ' Thick-bedded arenaceous and glauconitic limestone inter- f jj- stratified with layers of partially weathered greensand, j g the indurated strata largely composed of the shells of J ^ Turritella mortoni (Zone 9) 12 ] * Greensand bed, much weathered in its upper portions, and I ^ I filled chiefiy with Turritella mortoni in several thick layers; l^P-i also T. humerosa, Cucullaea gig antea, Cras.satellites alaeformis, ( Ostrea compressirostra, and many other species (Zone 8) . . . 25 Total 136 70 THE EOCEXE DEPOSITS OF MARYLAND Pleistocene. Eocene. V. Section three miles below Potomac Creek. ^ . Feet. Sand and gravel 2 [" Greenish-gray argillaceous sand (Zone 15). . . 4 Greenish-gray argillaceous sand with gypsum crystals (Zone 14) 5 ^ Light gray greensand with band containing Venericardia potapacoensis (Zone 13) 4 Greenish-gray argillaceous sand (Zone 12) 10 Indurated greensand with Vetiericardia potapacoensis (Zone 11) 1 Total 26 VI. Section at Head of Nanjemoy Creek. Feet. Pleistocene. Sand and gravel 4 t;, ^ f Greenish-gray argillaceous sand with layers containing g ^ j Venericardia potapacoensis (Zone 15) 11 Eocene. | Light gray greensand with gypsum beds (Zone 14) 6 ? [ Light gray greensand with Venei'icardia potapacoensis (Zone 1^) 3 ^ p_( Covered to tide 75 Total 99 Pleistocene. Eocene. a g VII. Section three miles above Popes Creek. Gravel and sand I Argillaceous greensand (Zone 15) \ Greensand with gypsum crystals (Zone 14).. [ Total Feet. 3 6 5 14 VIII. Section two and one-quarter miles above Popes Creek. Feet. Neocene. Diatomaceous earth Eocene. { Greensand with fossil casts (Zone 17) Greensand, somewhat argillaceous (Zone 16) L Grayish black argillaceous greensand (Zone 15) with num- J erous bands of Venericardia potapacoensis an^ other fossils, ( overlaid by a band of concretions 10 10 30 5 Total, 55 IX. Section of center of bluff at Woodstock. Pleistocene. Yellow and orange-colored sands and gravel 25 Neocene. Diatomaceous earth with Miocene fossils 5 Eocene. r.r Argillaceous greensand (Zone 17) Dark greensand more or less argillaceous with Mitra potoma- censis, Strepsidura subscalarina.^ Turritella potomacensis., Mesalia obruta, Corbula oniscus^ Meretrix subimpressa.^ Pro- tocardia lenis^ Pecten dalli, Ostrea sellaeformis, Glycymeris idoneus and Leda cultelliformis (Zone 16) Greensand Avith Tornatellaea bella., Cylichna venusta, Ringicula dalli, Venericardia potapacoensis and other forms (Zone 15) Total 6 20 6 62 MARYLAND GEOLOGICAL SURVEY’ 71 Neocene. Eocene. X. Section of bluff one mile below Popes Creek. Feet. Inches. Diatomaceous earth 40 ' Brown glauconitic clay much oxidized in places. ... 2 Band of pinkish-brown clay nodules in glauconitic clay 0 6 Dark glauconitic clay with many fossil casts 4 Concretions with occasional fossils 0 6 Argillaceous greensand with many casts and occa- sional shells 3 -I Concretions with many large specimens of Herco- glossa tuomeiji 0 6 Argillaceous greensaud with abundant fossils in- cluding Jferetrix subimpressa., Venericardia potapa- coensis, Hercoglossa tuomeyi.,Turritella potomacensis, Mesalia obruta, Protocardia lenis, Modiolus alabam- e?isis, Corbula subengonata., Mitra potomacensis, and many other fDrms (Zone 17) 6 Total 56 6 Other Sections. Along none of the other drainage lines is the sequence of Eocene strata as complete as in the Potomac river area. Several important local sections, composed of one or more members of the series, have been observed at many different points and may be correlated with one or the other of the divisions previously referred to. Some of the more important and typical sections follow. Section in ravine three-quarters of a mile east of Oxen., Prince George's County. Eocene. Feet. Inches. Yellow glauconitic sand 5 Indurated ledge 4 Black shell marl 4 Indurated ledge with Ostrea compressirostra 6 Shell marl, lower part packed with soft shells in- cluding Cucullaea gigantea^ Ostrea compressirostra, Meretrix ovata var. pyga Dosiniopsis lenticularis, Crassatellites alaeforrnis, Turritella humerosa 10 Total 10 Section in Railroad cut near Seat Pleasant, Prince George's County. Feet. Pleistocene. Gravel and loam 12 r . g I Glauconitic shell marl with OsG-ea 5 Eocene. Indurated ledge with Ostrea compressirostra.. Modiolus alabam- ensis, Crassatellites alaeforrnis, Corbula sp., etc 8 Total 72 THE EOCENE DEPOSITS OF MAKYLAND Eocene. Neocene. Eocene. Section o S east of bridge at Upper Marlboro, Prince George's County, f Feet. Glauconitie clay 22 Pink clay, without glauconite or fossils 22 Coarse glauconitic sand 32 Shell marl with Gibbida glandula, Fissuridea marlboroensis, Lticina aqtdana, Diplodonta marlboroensis, Venericardia plan- icosta var. regia, Fteria limula, Cucullaea gigantea, Leda parilis, Nucula ovula 2 Indurated ledge with Turritella mortoni, T. humerosa, Mesalia obruta, Calyptraphorus jacksoni, Panopea elongata, Meretrix ovata var. pyga Dosiniopsis lenticularis, Venericardia plani- costa var. regia, Crassatellites alaeformis, Astarte maryland- ica, Glycymeris idonens, Cucullaea gigantea, Leda. parilis, Nucula ovula Glauconitic sand full of tine fragments of shells accompanied by bryozoa, echinoid spines and foraminifera ; and with Ostrea compressirostra, Gryphaeostrea vorner, and Platidia (Known as Bryozoan sand) 5 Total 88 Section in ravine one mile south of Thrift, Prince George's County. Feet. Inches. Lead-colored clay with Miocene fossils 40 " Dark argillaceous greensand 7 Argillaceous greensand, packed with Venericardia po- tapacoensis 1 Dark glauconitic clay 3 Layer of Venericardia potapacoensis Greensand with many scattered specimens of Vener- icardia potapacoensis 3 Line of concretions Glauconitic clay with Venericardia potapacoensis 4 Dark greensand 5 Layer packed with shells of Venericardia potapacoensis 1 Argillaceous greensand 1 Line of concretions Argillaceous greensand 3 Greensand with Venericardia potapacoensis 1 Dark glauconitic clay 3 Layer of shells of Venericardia potapacoensis. [ Dark clay, with much glauconite 8 6 4 Total 74 6 Section on bank of Patuxent River one-quarter mile below mouth of Lyons Creek, Calvert County. Pleistocene. Sand and gravel 6 . ( Argillaceous greensand, with abundant casts of Eocene. 'o’ ^ Nanjemoy fossils 10 3 ( Line of concretions 2 Argillaceous greensand and talus 20 Total 50 0 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE VII Fm. 1.— LOWER EOCENE DEPOSITS ON SEVERN RIVER. Fig. 2. -indurated layer at UPPER MARLBORO, OVERLYING BRYOZOAN SAND. VIEWS OF EOCENE SECTIONS. MARYLAND GEOLOGICAL SURVEY 73 Section on South River at mouth of Broad Creek^ Anne Arundel Cou7ity. Eocene. ^ I Feet. Ferruginous sandstone full of casts of Turritella mortoni^ Venericardia planicosta var. regia, Crassatellites alaeformis, etc 10 Coarse oxidized greensand with occasional casts of Venericar- dia planicosta var. regia 34 Talus 34 Total 58 Section on north hank of Severn River 07ie mile above railroad bridge, Anne Arundel Coimty. Feet. Pleistocene. Sand and loam 5 Eocene. O" oS [ Coarse red, glauconitic sand partially indurated, with Ostrea I compressirostra, Cucullaea gigantea, Aferetrix ovata var. pyga, J Turritella lyiortoni, etc, i Red glauconitic sand and talus Total 20 50 75 Section 07i Chester River opposite Rolphs Landing, Kent County. Feet. Pleistocene. Sand and loam Neocene ? Drab clay with a thin band of limonite at the base Eocene. pH Coarse yellowish-red glauconitic sand irregularly indurated and with occasional pockets of coarse bright green glau- conitic sand Very coarse indurated glauconitic sand, much oxidized and iron-stained, with abundant angular quartz pebbles, fre- quently % inch in diameter, and with abundant casts of fossils, including Turritella mortoni, Panopea elongata, Pro- tocardia lenis, Venericardia planicosta var. regia, Crassa- tellites alaeformis, Ghjcymeris idoneus and Cucullaea gigantea Oxidized glauconitic sand, with occasional tubes of Vermetus 5 1 4 3 7 Total 20 Geological and Geographical Distribution of Species. The geological and geographical distribution of the species obtained from the Maryland Eocene has already been indicated in a general way in the discussion of the various stages, suhstages and zones. A much more complete presentation of the distribution of all the forms is given in the accompanying tables and in the chapter on systematic paleon- tology with which the report closes. Any further attempt at a discus- sion of the subject at this time would lead to much needless repetition. 74 THE EOCENE DEPOSITS OF MARYLAND SPECIES. LOCAL DISTRIBUTION. Aquia Formation. PISCATAWAY STAGE. PASPOTANSA STAGE. 1 Fort Washington. Seat Pleasant (Railroad cut). I Brooks estate, near Seat Pleasant. | Piscataway Creek. 1 Swan Creek, near Piscataway. 1 Glymont. 1 Aquia Creek. 1 Liverpool Point. 1 Reedy Run. 1 Clifton Beach. 1 Wades Bay. I Leeland. I Three miles west of Leeland. Collington. j One mile N. E. of Grimesville. Three miles W. of Pisgah. 1 Winchester. 1 Fredericktown Cecil Co. I 1 One mile N. E. of Piscataway. | 1 Tinkers Creek, near Piscataway. | 1 Pomonkey Neck. | 1 One mile S. E. of Mason Springs. | 1 Potomac Creek. | 1 Two miles below Potomac Creek. Paspotausa Creek. I Mattawoman Creek. I Upper Marlboro. | Hardesty. i 'S 1^ W 0 ® ® a § 0 1 Between Buena Vista and Collington. Crownsville. t Two miles south of South River. South River 1 mouth ot Broad Creek). South River (Sheckels farmi. Annapolis. I Severn River. Rolphs Landing. Harrisons Landing. 1 Southeast Creek. 1 Reptilia. * H: * : Pisces. * * * A.6tobcitis ciTcuatus Ag'assiz Syne.nhnd'U.K eJarhii astman * Cid.nnl.asi'pis p,lp,gn,nR (Ag-a.ssiy.i * * OdontaR'piR m,n,p,rntn, (Ag’assiy.'i * Odontaspis cuspidata (Agassiz) Otodv.x rthliq'ii.ti.R Ag-assiz * * * (In.rp.hn.rnd.nn, n.ii.rip.iiln.itist (Tlln ) . . frPiJpDP.p.rd n Tnt.id.pnn Agassiy. . Rphyrnn, prisp.n, Agassi 7 , JCipliiai^ ? rodinta (Clark) * Arthropoda. Ostracoda. HytbopAjpriR f a p ® P 33 P ® ® > ® 33 Crownsville. 1 Two miles south of South River. South River (mouth of Broad Creek). South River (Sheckels farm). Annapolis. Severn River. Rolphs Landing-. Harrisons Landing. 1 Southeast Creek. | Mollusca. Pelecypoda.— Co»tOiM6(L * I t i ! * .•I-. * * . . . . * * ? i" 1 1 Dosiniopsit^ lenticularis (Rog^ers) * :(= .. * I * •.(= ■ ■ *j.- * t V * * * H= * :(= 1" 1 Luciucb uhlci'i Clark * H= * * =(= 7,11.0.11111, inhif.o.i Clark Lucinn sp Venericardla planicosta var. regia Con. Vp.ii.p.vir.n.rriin, mn.njln.indlp.n, O. A M * ■■ * :(= * * H: * :(= Vp,ii.p.ri,p.n,rrlin, 'pntn.yin.p.np.n.sifi (1 A, IVT Crassatellites alaetormif< (Conrad) drn.siint.p.l.li.tp.st n.qu.in.n.n, (Olarkl > 1 1 * :i: '=*= * I I" * * H: * (Irn.ssn.f.p.lli.t.p.fi n.ltn. ^rinnrad i ? * Crassatellites sp Hc i:: Astn.rfp, m.n.ryla.n.flip.n, Cla,rk :i: * (Inrn.lllnphaga hrijn.n.i Clark r ■ * T*p,ripl,nm,a, H .^p I" 1 Ph.nln.rlnm.ifn, mn.rifln.iifli.p.n, Con * * * r 1.. If nd.inlii.fi n.ln.hn.mp.n.fiifi Aid 1 * * L. 'XTnrii, nl.ii.fi m.n.ryl.n.na.ip.ii.ft C. A M T,i.t,hnjih.n.(fn, m.n.ryl.n n.di.p.n. C \f * I" Annm.in, m.n.ryln.n.rHp.n, C AM Pp.p.t.p.ii. p.h.np.t.n.i'ip.n si.fi Aldrioh * =(= 1 Pp.p.f.p.n. f1.n,l,l.i. Clark * Pp.p.t.p.ii. jnliiisnni. Clf^rk =h' :*= 7* p, P.ten. .sp Ostrea compressirostra Say Ostrea compressirostra var. alepidota Dali Ostrea sellaeforinis Conrad * * * * * H: =.= * :C * * * * * Ostrea {Gryphaeostrea) vomer (Morton) * H= * * * • • frTijph.n.p.n. 1 'ip.si.p.iil n.ri.s T.amf^rok Pterin, l.im.ii.ln (Conrad 1 * Gl.ijPifm.p.ris i.dnn.eiis (Conrarl) ... * * * * •• Trigonoarca decisa (Con.) var Cucullaea gigantea Conrad Leda parva (Rog'ors) * * :*= :(= H: ? * :(= =(= * ••1 T,p,(1.n, p.ii.l.f.p.l.l.i.fnrm is (Potyprsl ..1 Leda improcera (Conrad) 1 T iP.fl.n. pn.riii.s (ConrnH) . . . * Leda pai'iHs var ■ '1 Leda potomacensis C. & M ! T,e(1.n. pl.iftnnp.il sis C A M :C * H: ..1 •* Leda tysoni C. & M lVii.Pii.ln. niMi.l.n. T.oa 1 * Nucula potomacensis C. & M I Molluscoidea. Brachiopoda. 'Terehrn.t.ii.l.n. hn.rl.n.n.i Morton.. j 1 H" Platid.ia ■marylandien. C. A AT •1. "I ! 1 Moleuscoidea. Bryozoa. T^isp.nspn.rsn rni'imis TTlrndi 1 1 .. 1 Pet.i.p.ii.l.ipnm. d i.plintiinin. (i A Tf .t Gavaria dumosa Ulricdi ..1 .. 1 , MARYLAXD GEOLOGICAL SURVEY 79 LOCAL DTSTRIBUTIOX GENERAL DISTRIBUTION. Nanjemoy Formation. POTAPACO STAGE. WOODSTOCK STAGE. MARYLAND PROVINCE. GULF PROVINCE. ( SPECIES. as 2 . X X g 0 2 1 i S a 2 ’= ^ 'Z West ot Port Tobacco. East of Port 'Pobacco. Half mile below (’haptd Point. oc 0 0 M s Woodstock. Zone 15. 1 One milo S. E. of Piscataway. I 1 Ravine north of Thrift. Charles Branch, between Rosaryvilie 1 and Upper Marlboro. Upper Marlboro (S. W. ot town). Upper Marlboro (deei) cut on new 1 R. R.). 1 Hills Bridge. 1 1 La 1‘lata. Woodstock. Zones 16 and L. Two miles above Popes (n-eek. 1 1 )^ miles above Popes Creek. | Popes Creek. Deep well at Chesapeake Beach (90- 93 feet). 1 Piscataway stage. 1 Paspotansa stage. 1 Potapaco stage. | Woodstock stage. I 1 Cretaceous. 1 Midwayan. Lower Chickasawan. 1 Upper Chickasawan. 1 Lower Claibornian. upper Claibornian. Jacksonian. | 1 Post-Eocene. Mollusca. Pelecypoda.- Co»D‘?med. 1 .1 • • V * * * . 1 *" ? .. ?. 3Xt/7'cX/ €-ssci C^onr3,(i • * ¥ * 2 ' * (Xto^Grs) T T ¥ , ¥ T ? Lu/C 1 uti ttijitiCDiOj Cl3.rk ? ? • * * * .. * 0 ■ 1 ' * • ; * . ! ; A A ' ,.i ^2 ^2 ? ? ? T^nericcu diet planicosta vai. C ? ? V . V dXCTlCCLTClXd VflClTyiClllCllCH I-'. * T . ^ ! Crassatellites alaef(yrmis (Conrad) * :(= Crassatelliles (Conrad) * *■* ' . ? ^slcu te mcirylcuidicct Clar ? ? Im/y-t'iilfin/linrt f^rkn V A T ; ^2 aKiouf , e -vr ■ ‘ ¥ V ! * 1 Anomia marylandica C. & M * * * * Pecten dalli Clark * ■ ? ! - * * * ? jjMnsoni Clark ¥ T ■■ + * nQl" ft Qq ¥ 1 .2 A- i •• ^ j, ^ ^ 1 'i~t ' /I f 1 1 * 1 ^ 1 C»ail * I 5^ 4 f t P n^f T*Pfl ') }^f}YY}P'T* fTVToT'i' Tl * ' *■ * .6 1 1 *6 1 * * 1 VO iX \ * ' 2 !■*•* A >i/» 1 / >vi 'i/l/vn Pti G {"'i^nvQcl * ¥ ? ? a1 2 I 94 /Ippion Prin *' * * : ^ ? T. *2 4^5 /y p/y ^y^/yvi'^Pfi * .2 L^dct , * * ¥ A *- ; ? ; * T rt/Xfi rnfiF^Uo rnr}r*cnX ^ ^ * * ¥ 1 * ‘ # ‘ ? 1 ■ Lecki potomacemv^ C^ & * * ¥ 6 * * * * * * Leda tysoni C. & M ATicitlrf oviilCL Loa 1 ' * * ; * * ¥ * ^2 2 4 ¥ Molluscoidea. Brachiopoda. Tp.rp.hrn.tii.ln, hrt.rlnni Morton i 1 i 1 •• i Pl.nt.i/lixi, mn,r]/l n.ndir.n. C. Sr. \f 1 * * Moi-luscoidea. Bryozoa. Discosparsci varians Ulrich 1 1 " 1 ‘ ■ 1 1 Fascipora Huhrnmnsa Ulrich * 1 * Reticuliporci dichotomcL G. & H. * ! .. 1 1 Cavarxa dumosa Ulrich 1 ^ Harris: Bull. Amer. Pal., No. 4. 2 jjarris: Bull. Araer. Pal., No. 9. ■‘Aldrich: Coastal Plain, Alabama. ® Harris: Proc. Acad. N. Sci., Phila., 1895. « Dali : Trans. Wag. Free Inst., vol. iii, pt. iv. 80 THE EOCENE DEPOSITS OF MAEYLAND LOCAL DISTRIBUTION. Aquia Formation. PISCATAWAY STAGE. PASPOTANSA STAGE. SPECIES. Molluscoidea. Bryozoa— Continued. Ceriopora micropora Goldf Heteropora? tecta Ulrich Memhranipora rimulata Ulrich Memhranipora spiculosa Ulrich Membranipora angusta Ulrich Reptoflustrella heteropora G. & H Bijlustra torta G. & H Eschara ? digitata Morton LunuHtes reversa Ulrich Cribrilina modesta Ulrich . Cribrilina crassula'U\riGh ... Lepralia subplana T'lrich Lepralia labiosa Ulrich Mucronella a^pera Ulrich COELENTERATA. Flabellum sp Turbinolia acuticostata Vaughan TrocJiocyathUH clarkeanus Vaughan Paracyathus marylandicus Vaughan — Bala nophy Ilia desmophyllum M-E & H. . . Eupsammia elaborata (Conrad) Protozoa. Textularia gramen d’Orbigny Textularia sagittula Defrance Textularia subangulata d’Orbigny Spiroplecta clarki Bagg Nodosaria afflnis (d’Orbigny) Nodosaria bacillum Defrance Nodosaria communis (d’Orbigny) Nodosaria consorbrina v.emaciata(Renss) Nodosaria sandbergeri (Reuss) Nodosaria obliqua (Linn6) Vaginulina legumen (Linne) ... Marginula costata (Batsck) Cristellaria gibba d’Orbigny Cristellaria rotatula ( Lamarck) Cristellaria radiata (Bornemann) Polymorphina austriaca (d’Orbigny) Polymorphina communis d’Orbigny Polymorphina compressa d’Orbigny Polymorphina elegantissima P. & J Polymorphina gibba d’Orbigny Polymorphina lactea (W. & J.) Polymorphina praelonga Terq Olobigerina bulloides d’Orbigny Discorbina bertheloti (d’Orbigny) Discorbina turbo (d'Orbigny) Truncatulina lobatula (W. & J.) Truncatulina ungeriana (d’Orbigny) Anomalina ammonoides (Reuss) Anomalina grosserugosa (Gumbeli Pulvinulina exigua var. obtusa Bur Pulvinulina schreibersii (d’Orbigny) . . . Nonionina afflnis Reuss Amphistegina lessonii d’Orbigny Plantae. Carpolithus marylandicus Hollick Carpolithus marylandicus var. rugosus H. 1 Fort Washington. I 1 Seat Pleasant (Railroad cut). I 1 Brooks estate, near Seat Pleasant. 1 Piscataway Creek. 1 1 Swan Creek, near Piscataway. I 1 Glymont. | 1 Aquia Creek. 1 Liverpool Point. I 1 Reedy Run. I 1 Clifton Beach. | Wades Bay. 1 Leeland. | 1 Three miles west of Leeland. I 1 Collington. I One mile N. E. of Grimesville. I Three miles W. of Pisgah. I Winchester. I Fredericktown, Cecil Co. I One mile N. E. of Piscataway. Tinkers Creek, near Piscataway. Pomonkey Neck. One mile S. E. of Mason Springs. Potomac Creek. Two miles below Potomac Creek. Paspotansa Creek. Mattawoman Creek. Upper Marlboro. Hardesty. | One mile west of Hardesty. Between Buena Vista and Collington. Crownsville. Two miles south of South River. I South River (mouth, of Broad Creek). I South River (Sheckels farm). I Annapolis. Severn River. Rolphs Landing. Harrisons Landing. Southeast Creek. I * * * * * * * * * : * * * * * * * * * * * * * * MAEYLAXD GEOLOGICAL SUKVEY 81 SPECIES. LOCAL DISTRIBUTION. GENERAL DISTRIBUTION. Nanjemoy Formation. POTAPACO STAGE. ? WOODSTOCK STAGE. MARYDAND PROVINCE. G 0 ® § 2 p GUEF PROVINCE. ® I 0 H A 0 P cc ® a o N X ® 2 o o a o o PlH Q >> 0 S ® 1 IZi o o o CS o r-i o PM o ® c o 53 .Q § O PM O DC a & 4-: 1 xi o 0 1 1 ■5 X ® 2 0 ® p- 0 PM ® > 0 53 CO ® 1 ® a 0 N 0 0 -c 0 0 > c3 £ 0 K 05 ® B ® G 4 ^ X H Sf-I 0 X 4J 0 G ® C as ® es 0 as G ® lg 0 P 2 ^ S3 2 X S3 0 a 0 0 2 0 X Th Ki s A G. P ® G G 0 4.3 G ® ® ® X 0 0 X ■3 eS G • Sas P 9 be s 'S p V. s s oS p n G 53 JO G 0 N X 0 s X 0 0 ® \i !o P ® P 53 i's ip ® ® p CO ® G 0 G p 0 .Q CO ® s ® ® p 0 PM i TO X 0 o3 P ® X 53 ® G CO ® X P G ®3 ^ ® ® G'tH ® ® TO P 9 be 1 >> 53 e3 ® ® be 1 G 0 G CO P 9 be c3 CO 0 cS G 53 0 p ® be M 0 4J 'a 0 0 G G >> G .'2 i g’ G G G X 0 X P 34 ® 0 P G* G G CO G .3*3 _® X P 34 ® G G P g’ G C 0 P P 34 ® 0 p G G G 34 0 X P 34 ® G P G G 0 CO X 0 G Molluscoidea. Bryozoa..— Continued. * ^10 ^ *TT 1 ^ * t-t /i /i*i YVi 't il rt 1 rTIr'i/^Vi TTlr.ir»Vi 7 " i i t i TT 1*1 a a H .» :: .. Eschci} ^ digitcUu ^^lovtoTi* ^auuLUCS leieisa uuicii 7^ 7 /¥ /» o i7/t TTl ’ Vi i^riDriti jia ^ ^ ^ ... ^epraiia siioi^iaua^^umcn ^ 7/^ ^ jp /7 7"T'l */^Vi .*. COELENTERATA. Flabellum sp * * • Turbinolia acuticostata Vaughan Trochocyathus clarkeanus Vaughan 1 Paracyathus marylandicus Vaughan Balanophyllia desmophyllum M-E & H... 8 :*=« Eupsammia elaborata (Conrad) * Protozoa. Textularia gramen d’Orbigny 1 L. Textularia sagtttula Defrance Textularia subangulata d’Orbigny * Spiroplecta clarki Bagg * * Nodosaria afflnis (d’Orbigny) Nodosaria bacilluni Defrance * Nodosaria communis (d’Orbigny) Nodosaria consorbrina v.emaciata ( Reuss) Nodosaria sandbergeri (Reuss) Nodosaria obliqua (Linne> ’1 Vaginulina legumen (Linne) * Marginula costata Batsch 1 Oristellaria gibba d’Orbigny Cristellaria rotatula (Lamarck) 1 Cristellaria radiata (Bornemann) 1 ♦ Polymorphina austriaca (d’Orbigny) .. 1 Polymorphina communis d’Orbigoy ..1 ■ ■ * Polymorphina compressa d’Orbigny • •1 • •1 Polymorphina elegantissima P. & j Polymorphina gibba d’Orbigny • • * 1 Polymorphina lactea (W. & j.) ‘i Polymorphina praelonga Terq ! • * Globigerina bulloides d’Orbigny * Discorbina bertheloti (d’Orbigny) Discorbina turbo (d’Orbigny) Truncatulina lobatula (W. & j.) 1 * 1 I Truncatulina unaeriana (d’Orhie-nv) * * Anomalina ammonoides (Reuss) Anomalina grosserugosa (Giimbeli i .. Pulvinulina exigua var. obtusa Bur .. Pulvinulina schreibersii (d’Orbigny) .. * * Nonionina afflnis Reuss .. Amphistegina lessonii d’Orbigny ..' 1 Plantae. Carpolithus marylandicus Hollick 1 * Carpolithus marylandicus var. rugosus H. . . ® Vaughan : Mono, xxxix, U. S. G. S. Cretaceous of N. J.,” Ulrich, see p. 2iii. “ Maastricht,” Ulrich, see p. 310. 6 82 THE EOCENE DEPOSITS OF MARYLAND Correlation of Deposits. Numerous attempts have been made to correlate the Eocene deposits of Maryland with those of other areas. Not only has the attempt been made to establish the equivalency between the Maryland deposits and those of adjoining states to the north and south, but also with the more distant Gulf region and with Europe. That the conclusions reached by the various investigators have been widely at variance has already been shown in the Historical Eeview, Some have considered the strata to represent but a small part of the full Eocene series, while others have regarded them to embrace a considerable portion of the same. These diverse views will be discussed in detail in the subsequent pages. Two methods of correlation are possible, one based upon physical, the other upon biological criteria. The faunal and floral characteristics of the formations find, therefore, interpretation only as the physical fea- tures are clearly understood since the geological and geographical range of species is determined to a large extent by conditions of sedimentation. The physical characteristics of a formation, therefore, bear a close relationship to its contained faunas, and cannot be ignored in the corre- lation of the deposits. It is a well-recognized fact thut the most trustworthy correlations are those based upon paleontological criteria, still the possibilities of varia- tion in the succession of organic forms in widely separated areas are so great that detailed correlation can seldom be satisfactorily attempted even where general equivalence is recognized. This is particularly true of the Eocene of the Middle Atlantic Slope where, as will be shown later, the range of species is quite different in certain particu- lars from that hitherto recognized in adjacent provinces. Such being the case, it is evident that whatever aid the physical criteria can afford should be employed in the interpretation of the Maryland Eocene de- posits. correlation of the deposits within the MIDDLE ATLANTIC SLOPE. It has generally been conceded that the Maryland and Virginia Eocene deposits constitute one and the same geologic province, a con- clusion which is well borne out by the fact that the strata are practically continuous and that the materials of the deposits and the fossils are MARYLAND GEOLOGICAL SURVEY" 83 freqiientl}' the same. It is evident, however, that the Maryland beds especially form the lower horizons, while the Virginia deposits repre- sent more largely the upper horizons of the Pamunkey group. In other words, the Aquia formation is more strongly developed in Maryland and the I^anjemoy formation more strongl}^ in Virginia, although the Xanjemoy formation is by no means lacking in Maryland and the same is true of the Aquia formation in Virginia. It is apparent that there must have been a gradual transgression of the Eocene deposits south- ward, since the Aquia formation gradually disappears under the IsTanje- moy to the south of the Potomac; on the other hand, the E’anjemoy formation is entirely absent to the northeast of the Patuxent valley, while the Miocene deposits have gradually transgressed over the Eocene from the Potomac valley northward, so that successively older horizons are found in contact with the Miocene in passing from the Potomac basin northeastward toward Delaware, where the Miocene strata ulti- mately come to rest directly on the Cretaceous deposits. The result of this ditferential movement is to limit the area of outcrop of the Nanjemoy formation in Maryland to the southern counties of the state, while the Aquia formation is continued across the Chesapeake Bay into the eastern counties as well and finally disappears beneath the Miocene cover not far from the borders of Delaware. It is evident, therefore, that higher Eocene horizons are found in central and southern Virginia than appear in Maryland, a conclusion borne out by the fact that the Ostrea sellae- formis zone with its accompanying fossils is much more strongly repre- sented in the valleys of the Pamunkey ,and James rivers than in the Po- tomac basin. Thick beds of Ostrea sellaefor7nis are found in the former areas, while only a few representatives of this species appear in the upper zone of the Woodstock substage on the banks of the Potomac. CORRELATION OF THE DEPOSITS WITH THE EOCENE FORMATIONS OF THE GULF STATES. By common consent the extensive and diversified series of Eocene deposits found in the Gulf region has come to be regarded as the type not only for the Atlantic Coast region but for the entire country as well. Dr. Dali, basing his conclusions both on his own work and on that of others in this area, has recently adopted the following classification of 84 THE EOCENE DEPOSITS OF MARYLAND American Eocene horizons. The sequence of stages from above down- wards as given by him is as follows: Jacksonian, Claihornian, Chickasawan, Midwayan. Paleontological Criteria. A comparison of the Maryland Eocene faunas with those represented in the Gulf area, which have primarily afforded the basis for the classi- fication above given, shows that the Maryland Atlantic Coast Eocene contains a great many species not represented in the Gulf, or of which the exact range there has not been well enough determined for com- parison (158 out of 207), while the majority of identical forms (49 in all) are of wide geological range, and are thus of little value in deter- mining the exact age of the deposits. There are enough distinctive species, however, as will be seen from a study of the table, to show that the Maryland Eocene must represent beyond any doubt the Chickasawan with both its upper and lower substages,^ and that from the Potomac basin southward through Virginia we also have in all probability the Lower Claibornian as well, with its Osirea sellaeformis zone. Whether higher or lower stages of the Eocene are represented in the Middle Atlantic Slope is a question that cannot be satisfactorily an- swered. There are no paleontological data that bear on this point, and the other evidence which may be brought forward cannot be regarded as conclusive. The non-fossiliferous zone at the base of the Aquia forma- tion may or may not be older than the Chickasawan, and the highest strata recognized as Eocene in central and southern Virginia have not been sufficiently studied to show whether they are or are not younger than the lower Claibornian. The following table contains the forms common to the Maryland and Gulf areas: 1 TheUpper Chickasawa^i used includes the Hatchetigbee and Woods Bluff (or Bashi) substages, while the Lower Chickasmoan includes the Bells Landing (or Tusca- homa), Greggs Landing and Nanafalia substages as differentiated in Alabama and Mississippi. MARYLAND GEOLOGICAL SURVEY, EOCENE, PLATE VIII, FtG. 1.— CONTACT OF NANJFJMOY AND AQUIA FORMATION,S IN VALLEY OF I'.EARD CREEK, ANNE ARUNDEL COUNTY. Fig. 2.— CONTACT OF NANJEMOY AND AQUIA FORMATION.S AT UFl’ER MARLRORO. VIEWS OF EOCENE SECTIONS. MARYLAND GEOLOGICAL SURVEY 85 Tornatellam hella Conrad Pleurotorna childveni Lea Cancellaria (jraciloides Aldrich yar. VolutUitheH petrosiis (Conrad) Caricelhi pyr uloides (Conrad) Fastis sahtennis Tleilprin Fastis inter str hit as Tleilprin Trophon suhlevis Harris Levifasas trabeatus Conrad.... Chrysodotnas euyonatas (Heilprin). Pyrula penita var Conrad Fusoficala jiwenis (Whitfield). . Jforio breindentata (Aldrich). . . Cypraea siaithi Aldrich Valyptraphoras triuodiferiis Conrad. Turritella mortoni Conrad Tarritella humerosa Conrad. ... Afesalia obrata (Conrad) Lanatia marylandica Conrad. . (\ilyptraea uperta (Solander) -/r Odostomia trapaqaara (Harris) Fiso ambilicaia (Lea) ('adalas abraptas Meyer and Aldrich -:f Corbala sabengonata Dali CorbnJa aldrichi Meyer Corbala oniscns Conrad Meretrix. ovata Conrad Meretrix siibhnpressa (Conrad) Dosiniopsis lettHcula^'is {RogeTS>) Lucina aqaiana Clark -x- Lucina astartif ormis Aldrich Lucina nhleri Clark -x Venericardia plardcosta var. regia'^ Conra*' Modiolus alabamensis Aldrich Pecten dalli Clark -x- Pecten choctarensis Aldrich * Pecten johnsoni Clark Ostrea cornpressirostra Say .... -x- Ostrea sellaef ormis Conrad Ostrea (Oryphaeostrea) vomer (.Morton) . . . -x- Pteria lirnala (Conrad) -x- C’hyvymeris idoaens (Conrad; -x- Trigoitoarca decisa (Conrad) Oacallaea gigantea Conrad Ltda parva (Rogers) Leda potomacensis Clark and Martin Xacula ovula I^ea Balanopbyllia desmophyllurn andH.. Eapsauimia el aborata {Convitd) ’ The V. planieosta of the Middle Atlantic Slope has been divided by the authors of this paper into several species, the var. regia being limited to the Aquia stage. The other species have not been recognized in the Gulf region, although further investi- gation may show one or more of them to exist there. 86 THE EOCENE DEPOSITS OF MARYLAND In the above table and in the following discussion only the mollusca and corals are included. Many of the other species occur outside of the state^ hut they are not considered here because the facts at hand are not complete enough to base upon them any generalizations concerning the distribution of the forms or any deductions concerning their significance. Aquia Stage . — The Aquia stage includes the following species that have been found in the Lower Chickasawan of the Gulf^ several of which, as will he seen by the table, also range downward into the Mid- way an, while others pass upward into the Upper Chickasawan and even into the Claibornian. Some of these forms also, as will he further seen from an examination of the table, are not confined alone to the Aquia, but range on into the Nanjemoy stage. The following Lower Chick- asawan species are found in the Aquia: Tornatellaea hella Conrad. rieurotoma childreni Lea. CJancellaria graciloides Aldricli. Volutilithes petrosus (Conrad). (Jaricella pyruloides (Conrad). Fnsus s^ibtenuis Heilprin. Trophon sziblevis Harris. Chrysodormts engonatus (Heilprin). Fasoficula juveuis ( WLitfleld). Morio hrevedentala (Aldrich). Calyptraphorus trinodiferus Conrad. Turritella mortoni Conrad. Turritella humerosa Conrad. Lunatia WMrylandica Conrad. f'ahyptraea aperta (Solander). A^<,so umMlicata (Lea). (?) Odo8tomia trapaquara^ (Harris). Cadulus abruptus Meyer and Aldrich. Corbula subengonata Dali. Corbula aldrichi Meyer. Meretrix ovata Conrad. Fosiniopsis lenticularis (Rogers). Lucina aqniana Clark. Pecten johnsoni Clark. Ostrea compressirostra Say. Giycymeris idoneus (Conrad). Cuctdlaea gigantea Conrad. Leda parva (Rogers). Nttcula ovula Lea. Balanophyllia desmophylbna M-E. and H. Enpsammia elaborata (Conrad). Of these forms a few only are restricted to the Lower Chickasawan, the remainder ranging on into the Upper Chickasawan and some on into the Claibornian as well. The restricted forms are: Trophon stiblevis Harris. Lucina aquiana Clark. Morio brevidentata (Aldrich). CucuUaea gigantea Conrad. Dosiniopsis lenticular'is (Rogers). All of these species, except CucuUaea gigantea, are confined to the Aquia stage. ' See the discussion of this form in the chapter on Systematic Paleontology, p. 156. MAEYLAXD GEOLOGICAL SUEVEY^ 87 The following species of the Aqiiia stage, on the other hand, have 'not been found below the Upper Chickasawan, viz.: F^cshs biter striatus Heilpriu. Pecteu choctavensis Aldrich. Lucina uhleri Clark. Pterici lininla (Conrad). Modiolus alabame?isis Aldrich. Of these, Pteria limula also occurs in the Claihornian. The Aquia stage also contains several species that have not been found below the Claihornian in the Gulf. They are: 31esalia obruta (Conrad). Corbula onisctis Conrad. {?) Odostomia trapaquara (Harris). The following species occur in the Jacksonian, viz.: Cadulus abruptus Meyer and Aldrich. Pecten dalli Clark. Corbula oniscus Conrad. Ostrea {Gyphaeostrea) vomer (Morton). None of them is of special significance. Before final conclusions are drawn from these comparisons, however, the fact must he taken into consideration that the Maryland beds have probably been examined at the present time more thoroughly and at a greater number of localities within the same limited area than those of the Gulf, and that some of the forms above mentioned may be shown upon further study to have a wider range in the Gulf than has been given to them. Due allowance must also he made for differences in judg- ment in the identification of species. At the same time, it is very clear that the species common to the Gulf and Middle Atlantic Slope differ materially in their geological range. This is evidently due in part to the difference in physical conditions in the two areas and also in part to migration. But after taking these facts into consideration it will be seen that the fauna of the iVquia is much more closely related to the Chickasawan as a whole than to either the Midwayan or Claihornian and that there is a somew^hat closer resemblance to the Lower than to the Upper Chickasawan. The distance, however, between the two areas, the difference in physical conditions and the possibilities of migration are too great to admit of any attempt to draw exact parallelism between the substages. Nanjemoy Stage . — The Nanjemoy stage contains the following species found in the Lower Chickasawan of the Gulf, all but one of which {Cucullaea gigantea) also range on upward into the Tapper Chickasawan or higher stages. They are: THE EOCENE DEPOSITS OF MAKYLAND Tornatellaea hella Conrad. Volntilithes petrosus (Conrad). Levifusus trabeatus Conrad. Cypraea smithi Aldrich. Calyptraphorus trinodifertis Conrad. Lunatia marylandica Conrad. Calyptraea aperta (Solander). Cadulus abruptus Meyer and Aldrich. Corbula subengonata Dali. Corbula aldrichi Meyer. Meretrix ovata (Conrad.) Pecteu jolmmni Clark. Glycymeris idoneus (Conradh Cucullaea glga'ntea Conrad. Leda parva (Rogers). The Nanjemoy stage contains the following species found in the Upper Chickasawan of the Gulf. They are: Tornatellaea bella Conrad. Volutilithes petrosas (Conrad). Fusas interstriatus Heilprin. Levifusus trabeatus Conrad. Cypraea smithi Aldrich. Calyptraphorus trinodif erus Conrad. Lunatia m,arylandica Conrad. Calyptraea aperta (Solander). Cadulus abruptus Meyer and Aldrich. C) Corbula subengonata Dali. Corbula aldrichi Meyer. Meretrix ovata Conrad. Among these species a few only asawan. They are: Fusus interstriatus Heilprin. Meretrix subimpressa Conrad. Lucina astartif ortnis Aldrich. Lucina uhleri Clark. Mey'etrix subimpressa Conrad. Lucina astartiformis Aldrich. Lucina uhleri Clark. 2Lodiolus alaLamensis Aldrich. Fecten choctavensis Aldrich. {?) Fecten johnsoni Clark. (.^) Ostrea sellaef oymiis Conrad. Fteria limula (Conrad). Glycymeris idoneus (Conrad). Trigonoarca decisa (Conrad). Leda parva (Rogers). Leda potomacensis Clark and Martin. are restricted to the Upper Chick- Modiolus alabamensis Aldrich. Fecten choctavensis Aldrich. Leda potomacensis Clark and Martin. Of these forms Meretrix subimpressa, Lucina astartiformis and Leda potomacensis are found only in the Nanjemoy stage. The following species of the Uanjemoy stage are found in the Lower Claihornian: Volutilithes petrosus (Conrad). Levifusus trabeatus Conrad. Fyrula penita var Conrad. Mesalia obruta (Conrad). Lmmatia marylandica Conrad. Calyptraea aperta (Solander). Cadulus abruptus Meyer and Aldrich. G) Corbula subengonata Dali. Corbula aldrichi Meyer. Corbula oniscus Conrad. Ostrea sellaeformis Conrad. Fteria limula (Conrad). O Glycymeris idoneus (Conrad). Trigonoarca decisa (Conrad). Among these forms Mesalia obruta is the only species that is confined to the Lower Claihornian, while three others do not pass the limits of the Claihornian stage, viz., Pyrula penita var., Corbula oniscus and (?) Ostrea sellaeformis. MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE IX. Fra. 1.— POPES CREEK BLUFF SHOWING ZONE OVERLAIN BY MIOCENE DIATOMACEOUS EARTH. Fra. ‘2.-RAILROAD CUT NEAR UPPER MARLBORO SHOWING NANJEMOY FORMATION OVERLAIN BY LATER DEPOSITS. VIEWS OF EOCENE SECTIONS. MAKYLAND GEOLOGICAL SUEVEY 89 Of the list above given, Levifusus trdbeatus, Pyr’ula penita var., Ostrea sellaeformis and Trigonoarca decisa are confined to the Nanjemoy stage. The following Nanjemoy species have been found in the Upper Clai- hornian: Fi/rula penita va7\ Conrstd. Corbula oniscus Conrad, Lunatia mai'ylandica Conrad. Ostrea sellaef oi'mis Conrad. Calyptraea aperta (Solander). Ptei'ia litnula (Conrad). hTone of these species are confined to the Upper Claibornian and two of them only, Pyrula penita var. and Ostrea sellaeformis, are dis- tinctively Nanjemoy forms. The following species occur in the Jacksonian, viz.: Cadulus ab^'uptus Meyer and Aldrich. Pecte7i dalli Clark. Co7'bula 07iiscus Conrad. Ost7'ea (Gyphaeost7'ea) voTner (Morton). Xone of them, however, has any special significance. It is thus shown that the Uanjemoy has faunal relationships both with the Chickasawan (and especially with the Upper Chickasawan) and with the Lower Claibornian. But in the Nanjemoy the lack of par- allelism in the succession of faunas between the Middle Atlantic and Gulf regions is even more noticeable than in the lower beds. The only conclusion which can be drawn is that the Uanjemoy of Maryland rep- resents such portion of the Chickasawan as lies above that represented by the Aquia, while the occurrence of the highly characteristic species, Ostrea sellaeformis, in the Uanjemoy stage in Maryland, although not so numerously or typically represented as in the still higher strata in central and southern Virginia, points to the possible Lower Claibornian age of the highest beds of the Maryland Eocene. Geological Criteria. The lithological and stratigraphical characteristics of the Eocene de- posits of the Middle Atlantic Slope afford some important criteria for the correlation of the strata. In the first place, the homogeneous nature of the materials, already referred to, is a significant feature, and indi- cates conditions undisturbed by important physical changes throughout the period of Eocene deposition. Again, the fact that the strata are so largely composed of secondary materials sliows that the position of accumulation was in the vicinity of a coast reached by no large sediment- 90 THE EOCEXE DEPOSITS OF MARYLAND bearing rivers, while at the same time, for the most part, sufficiently removed from the coast-line to be iinaifected by shore conditions. It is further evident that these deposits, which are so largely glauconitic, were very slowly accumulated, as has been shown in the case of the formation of greensand upon the beds of existing seas. When we compare these conditions of accumulation on the Middle Atlantic Slope with the conditions that prevailed in the Gulf region during Eocene time marked differences appear. In the latter area numerous rivers, draining the interior of the continent, discharged large quantities of material throughout much of the Eocene, making the deposits highly diversified. Instead of the greensands and greenish and black clays of the Middle Atlantic Slope, which no longer to any great extent characterize the strata, are found coarser beds of sand and clay, often partly calcareous, which give every indication of more rapid accumulation. To compare, therefore, the 200 to 300 feet of green- sands and clays of the Middle Atlantic Slope with one or two subdi- visions of hardly equal thickness in the Gulf region would scarcely be attempted, even upon geological grounds. The strata of the Middle Atlantic Slope must be represented in the Gulf by deposits many times their thickness. The State Geological Survey of Alabama has estimated the total thickness of the Eocene beneath the Jacksonian at 1500 feet, 600 feet of this belonging to the Chickasawan and 450 feet to the Claibornian. The Lower Chickasawan is given a thickness of about 350 feet and the Upper Chickasawan a thickness of about 250 feet, the Bells Landing division of the former having a thickness of less than 150 feet. The paleontological evidence previously cited, combined with the geological data here presented, show the far greater thickness of the geologically contemporaneous deposits in the Gulf as compared with those of the Middle Atlantic States. Furthermore the general relations of the strata, occurring as they do between the Cretaceous and Neocene along both the Atlantic and the Gulf coasts, give some indication of the continental movements to which each province was subjected. Although the movements may not have been absolutely contemporaneous, they nevertheless afford satisfactory MAllYLAXD GEOLOGICAL SURVEY 91 criteria for the broad correlation of the deposits, their more exact par- allelism being determined on other and more definite grounds. European Equivalents. Several attempts have been made to correlate the deposits of the Middle Atlantic Slope with those of Europe. The earlier attempts in this direction are presented in the Historical Eeview. Most of the con- clusions reached were based on very insufficient data, the faunas being inadequately studied and even the sequence of deposits not being in most instances fully understood; but even after Conrad" began his study of the Maryland Tertiaries and described more or less fully the rich faunas contained therein, his correlations were still based on very insuf- ficient knowledge. As the result of his investigations, he correlated the Eocene deposits of Mainland with the London Clay of England and the Calcaire Grassier of France. Lyell,'' during his visit to America in 1841, examined somewhat hur- riedly the Eocene deposits of the Middle Atlantic area, but attempted no detailed correlation, stating, however, that the Tertiary formations whicli he saw agree well in their geological types with the Eocene and Miocene beds in England and France.^^ Heilprin,"* in an important publication on United States Tertiary Geology, discusses the equivalency of the European and American Ter- tiary formations. In a chapter dealing with A Comparison of the Tertiary Mollusca of the Southeastern United States and Western Europe in Eelation to the Determination of Identical Forms,^^ he refers to the species which Conrad, Lea and Meyer had regarded as analogous to Euro- pean forms, and also discusses in detail all those species which he regards as the same or which have certain points of resemblance. Eeferring to the more important of these forms in an earlier portion of the same volume (p. 13) he says: “If such comparisons are of any value strati- graphically, we may fairly look upon the Maryland Eocene deposits — the ’Jour. Acad. Nat. Sci. Phila., voL vi, ISJO, pp. 205-217; Fossil Shells of the Tertiary, 1882, pp. iv, 0, 12, 18. •■’Proc. Geol. Soc. London, vol. iv, 1845, pp. 568-564; Quart. Jour. Geol. Soc. London, vol. i, 184.5, p. 429-430. ’’ Contribiitions to the Tertiary Geology and Paleontology of the United States, pp. 88-101. THE EOCENE DEPOSITS OE MARYLAND \}2 Piscataway sands below, and tlie Marlborougii rock above — as represent- ing a horizon nearly equal to that of the Thanet sands of England and the Bracheux sands of the Paris basin, or of the British Bognor rock (London clay). Tn either case they would be near the base of the Eocene series.'^ Dr. Dali/ in a recent article on ‘‘A Table of the North American Tertiary Horizons, Correlated with one Another and with Those of ^Yestern Europe, with Annotations,’^ correlates the Maryland formations with the Suessonian of Europe. As the writers of this report believe, however, that the Eocene of Maryland represents more than the lower Chickasawan of tlie Gulf, they would assign to the Maryland Eocene a somewhat wider range in the European Eocene. It seems highly probable that the Londonian and even the Parisian in part are also represented. The few identical species in the two areas have a wide range geologically, and are thus of little value for purposes of detailed corre- lation. Other species may ultimately be found in common, but more careful comparisons than have been made will be necessary to estab- lish this fact. Until such investigations have been made the correlation of the deposits on the two sides of the Atlantic can he at best only provisional. ' 18th Aun. Kept. U. S. Geol, Survey, pt. ii, 1898, pp. 327-348. SYSTEMATIC PALEONTOLOGY EOCENE EEPTILIA B. C. Case. PISCES Charles E. Eastman. AETHEOPODA E. 0. Ulrich. MOLLUSCA W. B. Clark and G. C. Martin. MOLLUSCOIDEA. BEACmOPODA W. B. Clark and G. C. Martin. BEYOZOA E. 0 Ulrich. COELENTEEATA T. Wayland Vaughan. ECHIUODEEMATA W. B. Clark and G. C. Martin. PEOTOZOA E. M. Bagg, Jr. PLAYTAE Arthur Rollick. VERTEBRATA. Class REPTILIA. Order CROCODILIA. Suborder ENSUCHIA. Family CROCODILIDAE. Genus THECACHAMPSA (CROCODILUS) Cope. Thecachampsa sp. Plate X, Pigs. 1, 2. Description. — A very large vertebra, probably dorsal, gives evidence of an animal of considerable size. The anterior face is deeply concave, and the rounded posterior face marked by a deep pit. It is impossible to determine whether the vertebra belongs to any one of the species below described and which are based on the teeth and jaws alone, and it therefore seems undesirable to assign a specific name to it. Occurrence. — Aquia Foematiox. Liverpool Point. Collection. — Maryland Geological Survey. Thecachampsa sekicodox (?) Cope. Plate X, Fig. 3. Thecachampsa sericodon Cope, 1867. Proc. Acad. Nat. Sci. Phila., p. 143. Thecachampsa sericodon Cope, 1869. Proc. Acad. Nat. Sci. Phila., p. 12 ; Amer. Nat., p. 91. Thecachampsa sericodon Cope, 1871. Trans. Amer. Phil. Soc., vol. xlv, p. 64, pi. v, figs. 7 and 8. (Pages 1-104 appeared in 1869.) Thecachampsa sericodon Cope, 187 -t. Proc. Acad. Nat. Sci. Phila., p. 363. Description. — A long slender tooth with a strong root represents this or an allied species. The specimen is water-worn and it is impossible to determine its characters exactly. Occurrence. — Aquia Foematiox. Clifton Beach. Collection. — Maryland Geological Survey. 96 SYSTEMATIC PALEONTOLOGY Thecachampsa contusor Cope. Plate Fig. 4. Thecachampsa contusor Cope, 1867. Proc. Acad. Nat. Sci., Phila., p. 143. Description. — This species was recognized by Cope as of doubtful value and he considered the forms placed here as possibly belonging to T. antiqua. A specimen in the collection has the characters assigned to contusor except that the section of the base is elliptical instead of rounded, and certainly does not belong to antiqua, so that it may be placed here provisionally. Occurrence. — Aquia Formation. Aquia Creek. Collection. — Maryland Geological Survey. Thecachampsa marylandica Clark. Plate X, Fig. 5. Thecachampsa marylandica Clark, 1895. Johns Hopkins Univ. Circ., vol. xv, p. 4. Thecachampsa marylandica Clark, 1896. Bull. 141, U. S. Geol. Survey p. 58, pi. vii, fig. 1. Description . — The specimen is a fragment of the jaw, described as moderately thick, the single complete and one partially preserved alveoli not far removed from one another. Teeth with elongate, slightly curved, conic crowns; basis circular, its diameter about one- third the length of the tooth; apex acute, circular; surface with fine prolongations and striations.^’ Clark, 1895. Dimension of the tooth 38 mm., diameter at base 12 mm. Occurrence. — Aquia Formation. Clifton Beach, Upper Marlboro. Collections. — Johns Flopkins University, Maryland Geological Survey. COPROLITE. Plate X, Fig. 6. Coprolite Clark, 1895. Bull. 141, U. S. Geol. Survey, p. 60, pi. vii, fig. 4. Description . — A reptilian coprolite of very perfect form. It is only one-half preserved. These coprolites are rather common in the forma- tion. Occurrence. — Aquia Formation. Clifton Beach. Collection. — Johns Hopkins University. MARYLAND GEOLOGICAL SURVEY or Order TESTUDENATA. Suborder CRYPTODIRA. Family CHELONIIDAE. Genus EUCLASTES Cope. Euclastes (?) sp. Clark. Plate X, Fig. 7. Euclastes {?) sp. Clark, 189.5. Johns Hopkins Univ. Circ., vol. xv, No. 4. Euclastes {?) sp. Clark, 1896. Bull. 141, U. S. Geol. Survey, p. 59. Description . — Several fragments from the carapace of a large sea turtle were found at Clifton Beach, but they were not sufficiently well preserved to identify the genus with certainty. Fragments of the costals show that the surface was smooth and the edges of the plate more or less rounded. The shields were relatively thin.’^ Clark, 1895. Occurrence . — Aquia Formation. Clifton Beach. Collectio7i . — Johns Hopkins University. Suborder TRIONYCHIA. Family TRIONYCHIDAE. Genus TRIONYX Geoffroy. Trionyx virginiana Clark. Plate XI, Figs. 1, 2. Trioyiyx virginiana Clark, 1895. Johns Hopkins Univ. Circ., vol. xv. No. 4. Trionyx virginiana Clark, 1896. Bull. 141, U. S. Geol. Survey, p. 59, pi. viii, fig'S. la and lb. Description . — Fragments of costals with tuberculated and ridged sur- faces, characteristic of the genus Trionyx. The longitudinal ridges are prominent, at times irregular and inosculate; relatively remote and separated by intervals of about twice their width; generally entirely disappear near the margins of the plates. Length of the largest fragment 130 mm., width 45 mm., thickness 18 mm. 98 SYSTEMATIC PALEONTOLOGY This fragment is evidently one of the terminal costals with no pro- jecting portion of the rib beyond the plate. Occurrence. — Aquia Fokmation. Aqnia Creek. Collections . — Wagner Free Institute of Science, Johns Hopkins Uni- versity, Maryland Geological Survey. Class PISCES. Order ELASMOBRANCH 1 1. Suborder TECTOSPONDYLI. Family MYLIOBATIDAE. Genus MYLIOBATIS Cuvier. The following remarks on the crushing pavement-teeth of the great Eagle-rays,^^ so abundant in the American and European Eocene, are extracted from an important paper on sharks’ teeth from the English Eocene by A. S. Woodward."" The dentition of each jaw in this genus [Myliodatis'] comprises large, flattened, hexagonal teeth, arranged in seven antero-posterior series. In very young individuals, the teeth are all approximately of equal size, hut quite early in life the median teeth begin to become rela- tively very broad, and as the animal grows, this disproportion of the median teeth gradually becomes greater and greater. When unworn or unahraded, the grinding surface of the teeth is covered with a thin enamel-like layer of gano-dentine, usually marked with antero-pos- teriorly directed striations; hut when this layer is removed, the tooth has a punctate appearance, owing to the exposure of the vertical nutri- tive canals traversing the underlying vascular dentine. In naming the fossils, it is thus necessary to take into account the size of the specimen, and remember that the surface markings depend on the state of preser- vation. It is also necessary to note that the dental plate of the lower jaw is flat, while that of the upper jaw curves round the supporting cartilage.” Proc. Geol. Assoc., vol. xvi, 1899, p. 3. MAEYLAND GEOLOGICAL SURVEY 99 Myliobatis copeanus Clark. Plate XII, Figs. 1, 2; Plate XIII, Figs. 2a, 2b, G, 7a, 7b. Myliobatis copeamcs Clark, 1805. Johns Hopkins Univ, Circ., vol. xv, p. 4. Myliobatis copea7ttis Clark, 1896. Bull. 141, U. S. Geol. Survey, p. 61, pi. vii, figs. 3a, 36. Description . — Dentition large and massive, the coronal contour strongly curved antero-posteriorly, and moderately arched from side to side in the upper jaw, but only very slightly so in the lower. Trans- verse sutures strongly and regularly concave toward the front in upper median teeth, less so in those of lower jaw, where they are sometimes slightly serrated. Upper median teeth relatively longer than the lower, but often variable in this respect; as a rule they are about five times as broad as they are long in the adult. Lateral teeth long and narrow, arranged parallel with the main axis. Surface smooth and polished when unabraded, but becoming longitudinally striated and fissured when worn. Oral surface of lower dental plate exhibiting a slight longitudinal depression along the central portion, and under surface cor- respondingly thickened, the latter having an arcuate contour from side to side. This species is very abundant in the Eocene of Maryland and Vir- ginia, but is apparently unknown beyond the limits of these states. A large series of specimens has been collected, thus facilitating a compari- son of successive growth stages, and of variations due to wear and other causes. It is a remarkably massive form, the thickness of the median teeth equalling that of if. pachyodon from the Miocene, and the trans- verse section being very much the same. In the latter species, how- ever, the transverse sutures of the median teeth are nearly straight, being only slightly curved backward at the extremities, whereas the present form is distinguished by the median sutures being uniformly concave toward the front. The curvature of the suture-lines is usually more pronounced in the upper dentition than in the lower, and in the newe.st-formed teeth than in those more anteriorly situated. The me- dian teeth of the lower dental plate are also somewhat shorter, as a rule, than those in the upper jaw, and the coronal contour is much less arched from side to side. 100 SYSTEMATIC PALEONTOLOGY Dental pavements are not uncommon showing as many as nine longi- tudinal series of median teeth intact (Plate XIII, Figs. 6, 7). One of the largest upper dental plates examined is from the Aquia Formation of Potomac Creek, and in this the median teeth are 6.5 cm. wide, 1.5 cm. long, and 3 cm. thick, not including the root. The antero-posterior curvature of the coronal surface is so great as to form a nearly perfect semicircle, having a diameter of 8 cm. and a periphery of over 12 cm. Nine of the median teeth are preserved in regular series, together with a portion of the lateral series on both sides. There is considerable re- semblance between this species and M. liolmesii from the Eocene of South Carolina. The type consists of fragmentary dental plates of the upper and lower jaws. Occuirence . — Xanjemoy Formation. Woodstock. Aquia Forma- tion. Clifton Beach, Liverpool Point, Aquia Creek, Potomac Creek. Collectio7is . — Johns Hopkins ITnivcrsity, Maryland Geological Survey. Myliobatis magister Leidyi Plate XII, Fig. 3; Plate XIII, Figs, la, lb. Jfyllobatis magister Leidy, 1876. Proc. Acad. Nat. Sci. Phila., p. 86. Myliobatis magister Laidy^ 1877. Jour. Acad. Nat. Sci. Phila., N. S., vol. viii, p. 283, pi. xxxiii, tig. 7. Myliobatis Iwlmesii Woodward, 1890. Cat. Foss. Fishes, Brit. Mus., pt. i, p. 122. Description . — Dentition very large and massive, the median teeth at least six times wider than long, their sutures curved backward near the lateral margins, and sometimes very faintly so in the central area. Coronal contour of upper dental plate uniformly arched from side to side, and also to an equal extent in a longitudinal direction; lower dental plate less curved antero-posteriorly than' the upper, and slightly de- pressed along the median line. Surface smooth when unworn, or with fine superficial striae slightly convergent toward the front. This gigantic species, ■which is exceeded in size only by the Egyptian M. peutoni, is not actually known to occur in Maryland, being confined, so far as known, to the Eocene Phosphate Beds of South Carolina. It is noticed in this connection, however, because of the interest attached MAEYLAXD GEOLOGICAL SUKVEY 101 to the original^ which is the largest specimen hitherto reported from this country. The figured specimen was found at Ashley, South Caro- lina, and is preserved in the Mnsenm of Comparative Zoology at Cam- hridge, Massachusetts. The strong curvature of the oral surface, which is equal in both longitudinal and transverse directions, together with the proportions and wavy sutures of the median teeth prove it beyond all doubt to he the upper dentition, previously unknown, of a species founded by Leidy on a unique lower dental plate from the same locality, to which he applied the name M. magister. Leidy himself, and follow- ing him A. S. Woodward, were of the opinion that the type-specimen might represent the lower dentition of M. Iwlmesii Gihhes, which was described from a supposed upper dental plate with strongly curved su- tures. The specimen in the Cambridge collection, however, completes our knowledge of the dentition of ill. magister, and we must look else- where for the opposing dentition of Gihhes’ species. The latter, as has already been intimated, appears to he only very slightly different from J/. copeamis of this state. The type consists of a lower dental plate. Collections. — Philadelphia Academy of Natural Sciences, Museum of Comparative Zoology, Cambridge. Genus AETOBATIS Muller and Henle. In this genus there is hut a single series of very broad, flat teeth, those of the upper jaw only differing from the median teeth of Mylio- hatis in their truncated lateral ends. The lower dentition is very nearly flat, and the teeth are all more or less strongly curved or angularly bent in the middle. The coronal surface is smooth or slightly striated, and the attached surface of the root longitudinally ridged or grooved. Woodward^ remarks that “In this genus there is much less variability in the relations of the length and breadth of the teeth according to age than in Myliolatis ; but the form of the lower teeth is so inconstant, that species cannot be determined upon the evidence of the lower denti- tion alone.” ' Cat. Foss. Fishes^ British Mmeum, pt. i, 1889, p. 138. 102 SYSTEMATIC PALEONTOLOGY Aetobatis aecuatus Agassiz. Plate XIII, Figs. 3a, 3b, 8. Aetohatis arcuains Agassiz, 1843. Poiss. Foss., vol. iii, p. 337. Aetohat'h arcnatuti Cope, 1867. Proc. Acad. Nat. Sci. Pbila., p. 139. Aetobatis profundus Cope, 1867. Loc. cit.y p. 139. Aetohatis arcuatns Leidy, 1877. Jour. Acad. Nat. Sci. Phila., 2nd ser., vol. viii, p. 245, pi. xxxi, tigs. 14-18. Aetobatis prof undus Leidy, 1877. Loc. cit.., p. 346, pi. xxxi, tigs. 19, 20. Descriptio7i. — This species is known only by fragments belonging chiefly to the lower dentition, and consequently cannot be accurately deflned. Founded originally on detached teeth from the Miocene of Switzerland, it has been recognized by Cope and Leidy from the corre- sponding horizon in Maryland, but has not been hitherto reported from the Eocene. It would appear to be very rare in the latter formation, as only a few detached teeth have been collected by the Maryland Geo- logical Survey. A number of Miocene forms from Charles county are flgnred by Leidy (loc. cit., 1877, pi. xxxi), Avho very plausibly suggests that the narrow rounded crowns described by Cope as A. profundus are in reality only worn anterior teeth belonging to the species under con- sideration. Other species of Aetohatis occur in the Eocene of Xew Jer- sey and South Carolina. Occurrence. — Xanjemoy Formation. Popes Creek. Aquia Forma- tion. Aquia Creek. Collection . — Maryland Geological Survey. Suborder ASTEROSPONDYLl. Family CESTRACIONTIDAE. Genus SYNECHODUS Woodward. This genus of Cestraciont sharks is known by the nearly complete dentition and parts of the skeleton in the Lias of England, vdiere it accompanies such allied forms as Hyhodus, Acrodus, etc., and detached teeth have also been described from the Cretaceo-Tertiary of Xew Zea- land. Its remains have not been heretofore reported, however, from strata of undoubted Tertiar}- age, and the following species ma}" be re- garded as the latest survivor of the genus of which we have any record. MARYLAND GEOLOGICAL SURVEY^ 103 Sy^nechodus clarkii n. sp. Plate XIV, Figs. 5a, 5b, 5c. Description . — Teeth of small or moderate size, but of relatively stout proportions, and symmetrical. Median cone sharply recurved, gently tapering, smooth, convex on both faces, and cutting edges not conspicu- ously defined; on either side, two much smaller cones, the external one being the lesser of the two. Eoot massive and somewhat turgid, pro- duced in the arc of a circle on the inner face, and flat below; nutrient foramen small. The total height of the tooth, oriented in its natural position, is 7 mm. The distance from apex to base of crown, measured along its recurved outer face, is 6 mm. The width and thickness of the crown at its base are equal, amounting to 3 mm., whereas the corresponding measure- ments of the root, taken at their maximum, are 8 mm. and 4 mm. re- spectively. This unique tooth appears sufficiently well characterized, notwith- standing that the lateral cones are broken off above the base, to warrant recognition as a distinct species, and it may be fittingly named in honor of the State Geologist. Much interest is attached to the fact of its coming from a Tertiary horizon. Occurrence . — Aquia Formation. Liverpool Point. Collection . — Maryland Geological Survey. Family LAMNIDAE. Genus ODONTASPIS Agassiz. The teeth of this genus are very similar to those of the Cretaceous Scapanorhynchus, a survivor of which has been recognized in Mitsiku- rina of the present day; and they are also, as remarked by Agassiz, very difficult to distinguish from those of Lanina. The crown is high, nar- row and compressed in all except a few hindermost teeth, and adjacent to it are one or two pairs of lateral denticles, generally sharply pointed. The anterior teeth are especially high-crowned, comparatively large and. slender, with a much produced bifurcated root. 104 SYSTEMATIC TALEONTOLOGY Odontaspis elegans (Agassiz). Plate XIV, Figs. 2a, 2b, 2c, 3a, 3b, 3c. Lamna elegans Agassiz, 1843. Poiss. Foss., vol. iii, p. 369, pi. xl6, fig. 24. Lamna elegans Gibbes, 1849. Jour. Acad. Nat. Sci. Pbila., 2nd ser., vol. i, p. 196, pi. XXV, figs. 98-102 (? figs. 96, 97). Lamna elegans Emmons, 1858. Kept. Geol. Surv. N. Car., p. 239, figs. 70, 71. Lamna elegans Noetling, 1885. Abb. Geol. Spenialk. Preussen u. Thiiring. Staaten, vol. vi, pt. 3, p. 61, pi. iv. Odontaspis elegans Woodward, 1889. Cat. Foss. Fishes, British Mus., pt. i, p. 361. Odontaspis elegans Clark, 1895. Johns Hopkins Univ. Circ., vol. xv, p. 4. Odontaspis elegans Clark, 1896. Bull. 141, U. S. Geol.- Surve}’, p. 62. Odontaspis elegans Woodward, 1899. Proc. Geol. Assoc., vol. xvi, p. 8, pi. i, figs. 15-18. Description . — Anterior teeth with a very high and narrow crown, only slightly curved, the inner face strongly striated longitudinally, and scarcely flattened in the middle. A single pair of small, prickle-like lateral denticles, and nutritive foramen on the prominent inner side of the root placed in a deep cleft. Lateral teeth with an almost equally slender, but less elevated crown, which is similarly striated and flanked with relatively large, slender denticles. The two branches of the root are long, compressed and generally pointed. This is the most abundant of all Eocene sharks’ teeth in Maryland and Virginia, but is of rare occurrence in the Miocene. It is a some- what smaller form than 0. macrota, and tlie anterior teeth of the two species are so much alike that it is ditficnlt to separate them. This is especially true of worn specimens (Plate XIV, Fig. 2) where the den- ticles are wanting and the striation of the inner face inconspicnons," and chief reliance must be placed on the narrowness of the crown. The anterior teeth sometimes exceed 4 cm. in total height. Dr. F. Xoetling, and following him, Jaekel and Smith Woodward, have been chiefly in- strumental in reconstructing the dentition of this and other species of Odontaspis. The type consists of teeth and associated vertebrae in the museum of College of Surgeons, London. Occurrence . — Aquia Formation. Aquia Creek, Fort Washington, Liverpool Point. Collections . — Jolms Hopkins Fniversit}', Maryland Geological Survey. 1 On the striation of Selachian teeth, see J. Probst, Wurtt., Jahresb., vol. xv, 1859, p. 100. 3IARYLAXD GEOLOGICAL SURVEY 105 Odoxtaspis macrota (Agassiz). Plate XI Y, Figs. 4a, 4b. Otodus macrotiis Ao-assiz, 184o. Poiss. Foss., vol. iii, p. 273, pi. xxxii, figs. 29-31. Lamna elegans Agassiz, 1843. Tom. cit.., p. 289, pi. xxv, figs. 1-7 ; pi. xxxviia, figs. 58, 59. Lamna compressa Agassiz, 1843. Tom. cit., p. 290, pi. xxxviia, figs. 35-42. Lamna compream Gibbes, 1849. Jour. Acad. Nat. Sci. Phila., 2nd ser., vol. i, p. 197, pi. xxv, figs. 107-112. Otodus mac rot us Gibbes, 1849. Tom. cit., p. 200, pi. xxvi, figs. 2, 143, 144. I^amna compressa Emmons, 1858. Kept. Geol. Surv. N. Car., p. 240, figs. 72, 75, 7(5. Odontaspis rnacrota O. Jaekel, 1895. Mem. Comite Geol., St. Petersb., vol. ix, pp. 11, 29, pi. i, figs. 8-17. Odontaspis rnacrota Woodward, 1899. Proc. Geol. Assoc., vol. xvi, p. 9, pi. i, figs. 19, 20. Description . — Anterior teeth much compressed, the inner face with fainter, more wavy and more interrupted strioe than those of 0. elegans. Typical lateral teeth much compressed, croivn with sharp cutting edges and a faintly striated inner face; outer coronal face gently convex. A single pair of large and broad lateral denticles, iisnally rounded, but sometimes obtusely pointed. This species is tolerably abundant in the Eocene of various localities in Maryland and Virginia, especially at Liverpool Point on the Potomac river. The lateral teeth rarely exceed 2.5 cm. nor the anterior 3.5 cm. in total height. Occurrence . — Xaxjemoy^ Formatiox. Woodstock. Aquia Forma- Tiox. Aqnia Creek, Fort AYashington, Liverpool Point. Collection . — Maryland Geological Survey. Odoxtaspis cuspid ata (Agassiz). Plate XIY", Figs, la, lb, Ga, Gb. Lamna cuspidata Agassiz, 1843. Poiss. Foss., vol. iii, p. 290, pi. xxxviia, figs. 43-50. lAirnna cuspidata Gibbes, 1849. Jour. Acad. Nat. Sci. Phila., 2nd ser., vol. i, p. 197, pi. xxv, figs. 103-10(5. Lamna clavata Agassiz, 1856. Kept. Pac. R. R. Explor. and Surv., vol. v, p. 310, pi. i, figs. 19-21. Tjumna clavata Agassiz, 1850. Amer. Jour. Sci., ser. ii, vol. xxi, p. 275. Odontaspis hopei Noetling, 1885. Abb. Geol. Specialk., Preussen u. Thiiring, Staaten, vol. vi, pt. 3, p. 71, pi. v, figs. 1-3. Odontaspis cuspidata Woodward, 1899. Proc. Geol. Assoc., vol. xvi, p. 7, pi. i, figs. 12-14. 106 SYSTEMATIC PALEONTOLOGY Description. — Teeth scarcely distinguishable from those of 0. elegans except by their slightly smaller size and by the absence of striae upon the inner coronal face. Anterior teeth much elevated and narrow, hut moderately stont. Lateral denticles of both anterior and lateral teeth occasionally flanked by a smaller secondary pair. Teeth belonging to this species accompany those of 0. elegans and 0. macrota in various localities of Maryland and Virginia, but are less numerous than either of these forms. From the Miocene of this state, very few examples have been obtained. In some specimens two well- developed pairs of lateral denticles occur, as shown in Plate XIV, Fig. 1, and also in Figs. 86a and 87a of Emmoifls Xorth Carolina Geological Survey Eeport (1858), p. 241. Occurrence. — Xanjemoy Formation. Popes Creek, Woodstock. Aquia Formation. Mattawoman Creek, Fort Washington, Liverpool Point. Collection . — Maryland Geological Survey. Genus OTODUS Agassiz. Nearly all the species assigned by Agassiz to this genus have been distributed by subsequent authors among Lamna, Odontaspis and Oxyrhina. Noetling even goes so far as to refer the type-species 0. obliquus, to the genus C arcliarodon, although the coronal margin is never distinctly serrated. The best modern opinion is that the pecu- liarly robust teeth belonging to this species should be provisionally re- tained in the place provided for it by its founder, and along with this should be ranged a second, somewhat smaller species occurring in Eng- land and Eussia, known as 0. trigonalis (Jaekel). Otodus obliquus Agassiz. Plate XV, Figs. l-4c. Otodus obliqmts Agassiz, 1843, Poiss. Foss., vol. iii, p. 267, pi. xxxi, pi. xxxvi, figs. 22-37. Otodus obliquus Gibbes, 1849. Jour. Acad. Nat. Sci. Pliila., 3ud ser., vol. i, p. 199, pi. xxvi, figs. 131-137. Lamna acuminata Gibbes, 1849. Loc. cit., p. 197, pi. xxv, figs. 113, 114 (? not fig. 115). Lamna {?) obliqua Clark, 1895. Johns Hopkins Univ. Circ., vol. xv, p. 4. Lamna {?) obliqua Clark, 1896. Bull. 141, U. S. Geol. Survey, 61. Otodus obliquus Woodward, 1899. Proc. Geol. Assoc., vol. xvi, p. 10. MARYLAND GEOLOGICAL SURVEY 107 Description . — Teeth robust, attaining to a very large size; crown moderately compressed, sharply pointed, with one broad acuminate pair of lateral denticles, and, in the smaller teeth, an additional pair of more slender denticles. Outer coronal face flat or slightly convex, without folds; inner face smooth. Inner face of the root prominent, and nutri- tive foramen not sunk in a groove.” Agassiz, 1843. These very robust teeth attain a large size, the crown sometimes meas- uring 5 cm. in height (cf. Plate XV, Fig. 4), but the majority of speci- mens do not exceed 3 cm. in total height. The anterior teeth (Plate XV, Fig. 1) are narrow and erect, with rather deeply cleft root, and frequently with only one or no lateral denticles; they are sometimes diffi- cidt to distinguish from the anterior teeth of Odontaspis macrota. The lateral teeth are distinguished by their broader, more compressed and usually obliquely directed crowns. The small hindermost teeth are often extremely broad-based, but here as elesewhere in the jaws, much individual variation occurs. It does not appear possible, however, to recognize more than a single species in the American Tertiaries. Xu- merous examples are found in the Eocene of Maryland, Virginia, Xew Jersey, and the Carolinas. Occurrence. — Aquia Formation. Liverpool, Aquia Creek, Glymont. Collections. — Maryland Geological Surve}q Johns Hopkins University. Genus CARCHARODON Agassiz. The teeth of Carcliarodon attain enormous size, exceeding those of all other Selachian genera. They are triangular, usually erect, and re- semble those of Oxyrliina and Otodus except that the edges of the com- pressed crown are always serrated. Some species are without lateral denticles, others have a single pair, serrated like the crown. The genus enjoyed V world-wide distribution during the Eocene and Miocene, and was exceedingly abundant in various localities of both hemispheres. In the South Carolina Phosphate Beds the teeth are so numerous as to be of no mean commercial importance. 108 SYSTEMATIC PALEONTOLOGY Cakcharodon auriculatus (Blaiiiville). Squalus auriculatus Blainville, 1818. Nouv. Diet. cl’Hist. Nat., vol. xxvii, p. 884. Carcharoclon acuiidens Gibbes, 1847. Proc. Acad. Nat. Sci. Pliila., p. 267. Carcharodon augustideiis Gibbes, 1848. Jour. Acad. Nat. Sci. Pbila., 2nd ser., vol. i, p. 145, pi. XIX, tigs. 10-18, pi. xx, pi. xxi, tigs. 87-38. Carcharodon acuiidens Gibbes, 1848. Torn, cit.^ p. 146, pi. xxi, tigs. 39-41. Carcharodon rectus Agassiz, 1856. Kept. Pac. R. K. Explor. and Surv., vol. v, p. 816, pi. i, tigs. 89-41. Carcharodon rectus Agassiz, 1856. Araer. Jour. Sci., ser. ii, vol. xxi, p. 274. Carcharodon crassidens Emmons, 1858. Kept. Geol. Surv. N. Car., p. 283, tig. 59a. Carcharodon contortidens Emmons, 1858. Loc. cit.^ p. 288, tig. 60. Carcharodon angustidens Leidy, 1877. Jour. Acad. Nat. Sci. Pliila., 2nd ser., vol. viii, p. 258. Carcharodon angustidens Noetling, 1885, Abb. Geol. Specialk., Preussen u. Thiir. Staaten, vol. vi, pt. 3, p. 82, pi. vi, tigs. 1-3. Description . — Teeth robust, comparatively narrow, with a pair of broad lateral denticles; outer coronal face flat or slightly convex. Lat- eral denticles especially large in the lateral teeth, which have a very narrow oblique crown.^^ Blainville, 1818. This species is apparently very rare in the Maryland Tertiaries, only a single fragmentary example having been obtained from the Eocene of Popes Creek, and very few from the Miocene. Owing to its imper- fection, no figure is given of the Eocene tooth, but it is to be noted that the lateral denticles are very feebly developed, so that the reference to this species is not absolutely certain. Occurrence. — Nanjemoy^ Formation. Popes Creek. Collection . — Maryland Geological Survey. Family CARCHARIIDAE. The teeth of this family of man-eating sharks are very abundant in the Tertiary of all countries, and closely resemble those of the Lamnidae. They differ from the latter ho’wever, in their internal struc- ture, being holloAv in the center throughout life, and with minute tubules radiating from the pulp-cavity across the dentine. The teeth are so much alike in existing genera that vdien found in the detached fossil condition it is often impossible to separate them. For instance, the upper teeth of llypoprion are scarce!}’’ distinguishable from those of Galeus, and isolated teeth of Galeocerdo and Spliyrna are difficult to dis- tinguish from tliose of C archarias. It is rather surprising that the last- MARYLAND GEOLOGICAL SURVEY 109 named genus does not appear to be present in the Maryland Eocene, and the teeth of Galeocerdo contortiis, although very abundant in the corre- sponding horizons of Virginia and South Carolina, are likewise wanting in this state. Hemipristis serra is another common form in the Carolina Eocene, and also in the Miocene of the Atlantic Slope extending as far north as Gay Head, Massachusetts, but is apparently unknown in the Eocene of ^laryland and Virginia. Genus GALEOCERDO Miiller and Henle. The teeth of this genus are serrated on both margins, have the pos- terior edge deeply notched, and the apex more or less sharply inclined backward. As already remarked, some species are very difficult to dis- tinguish from Carcharias, and in the case of the teeth referred to G. mmor by Gibbes, Emmons and Cope, comparisons show that these really belong to species of Carcharias. Galeocerdo latidens Agassiz. Plate XIV, Eig. 8. Galeocerdo latidens Ajjassiz, 1843. Poiss. Foss., vol. iii, p. 231, pi. xxvi, figs. 22, 23 (? tigs. 20, 21). Galeocerdo latidens Gibbes, 1849. Jour. Acad. Nat. Sci. Pbila., 2nd ser., vol. i, p. 192, pi. XXV, tig-s. 59-02. Description. — Teeth broad, mostly low-crowned, the largest meas- uring about .024 cm. across the base. Anterior coronal margin only slightly arched, except near the apex; apex above the posterior notch small, narrow; margin below the posterior notch long, straight and much inclined; root large. Serrations of the coronal margin very prominent.” This species is not uncommon in the Maryland Miocene, but as yet only a single example has been obtained from the Eocene of this state. Its jireservation is not so good as might be desired, and it is rather under the average size attained by this species. Occurrence . — Xanjemoy" Formation. Moodstock. Collection. — Maryland Geological Survey. Genus SPHYRNA Rafinesque. The small teeth belonging to this genus are similar in both jaws, oblique, with a slight posterior notch, and margins smooth or serrated. Their resemblance to the teeth of Carcharias has already been noted. 110 SYSTEMATIC PALEONTOLOGY Sphyena pkisca Agassiz. Plate XIV, Figs. 7a, 7b. Hphyrna py'isca Agassiz, 1848. Poiss. Foss., vol. iii, p. 334, pi. xxvia, flgs. 35-50. Sphyrna prisca Gibbes, 1840. Jour. Acad. Nat. Sci. Pbila., 2nd ser., vol. i, p. 104, pi. XXV, figs. 88-00. Lamna compressa {pars) Emmons, 1858. Kept. Geol. Surv. N. Car., p. 340, figs. 70-81. {?) Sphyrna denticulata Emmons, 1858. Loc. cit.^ p. 341, fig. 84a. Description . — Teeth small, broad, gently oblique, often erect, with finely serrated edges. This species is very abundant in the Eocene of South Carolina and Miocene of Maryland, but only two or three rather imperfect examples have been obtained from the Eocene of this state. There was also found one doubtful tooth, which may possibly belong to a distinct species. Occurretice . — Aquia Eoemation. Liverpool Point. Collection . — Maryland Geological Survey. SELACHIAN VERTEBRAE. Detached vertebrae of the Asterospondylic type, consisting of calcified cartilage and therefore not well adapted for preservation, are occasionally met with in the Eocene of Clifton Beach and a few other localities in Maryland and A'irginia. Some of the larger ones are but slightly con- cave on both faces, and belong without doubt among the Lamnidae, possibly to Otodus or CarcJiarodon. Detached vertebrae of both Elas- mobranch and Teleost fishes are much more common in the Miocene than Eocene, and represent a considerable variety of forms. In Plate XII, Figs. 7a and 7& are represented detached vertebrae of an indeter- minate species of bony fishes. Subclass TELEOSTOMl. Order ACTINOPTERYGll. Kemains of bony fishes are very rare in the Tertiary of the Middle Atlantic Slope, and are confined to detached vertebrae, otolites and por- tions of the dentition. A few species founded on detached teeth from MAEYLAXD GEOLOGICAL SUEVEY 111 the Eocene of South Carolina have been described by Leidy/ and a singular bone from the same horizon supposed to belong to Platax is figured by Gibbes." Cope records in all only one species of Actinoptery- gians from the Miocene of Maryland {Spliyraena speciosa), and five from the same horizon in New Jersey, as follows: Spliyraena speciosa, S. siloviana, Pliasganodus gentry i, C tommy odus irregularis, and Pliyllo- dus curvidens.^ The last-named genus is of exceptionally rare occur- rence in the American Tertiary, being known only by the four detached dental plates noticed by WymaiT and l)y Marsh;" The peculiar teeth first described by Leidy from the Cretaceous of New Jersey under the name of Ischyrliiza, occur also in the Miocene, of Maryland and North Carolina, if we may credit the statements of Cope and according to this author certain coalesced caudal vertebrae hypnral fans accompanying the Cretaceous teeth and occurring also in the Eocene of Maryland and South Carolina should be referred to this genus, which he claims is re- lated to the Esocidae. It is much more likely, however, that the Cre- taceous fans belong to ProtospJiyraena or some similar form, and that the Tertiary fans, which all agree in having the terminal centrum at- tached, belong to one or more species of Sword-fishes. Genus XI PH IAS Linnaeus. Fragmentary remains of Sword-fishes have been met with from time to time in various Tertiary horizons, but in most cases are insufficient for accurate identification. Detached rostra and hypnral fans of large size, both probably belonging to Xipliias or some related genus, are not uncommon in the Eocene of South Carolina. A number of such re- mains, inclndifig the types of X. rohustus Leidy, are preserved in the Holmes Collection belonging to the American Mnsemn of Natural His- tory in New York. Here also is to be seen the tooth of Ischyrliiza mira figured by Leidy in Holmes’ Post-Pleiocene Fossils of South Carolina (Plate XXV, Figs. 3, 4), which is the most perfect specimen of that ’ Jour. Acad. Nat. Sci. Pbila., 2nd ser., vol. viii, 1877, pp. 254-257, pi. xxxiv. ^ Ibid., vol. i, 1849, p. 300, pi. xlii, figs. 10-13. ^Proc. Amer. Philos. Soc., vol. xiv, 1875, p. 362. 4 Amer. Jour. Sci., ser. ii, vol. x, 1850, p. 234. sProc. Amer. Assoc. Adv. Sci., 18th Meet., 1870, p. 228. •^Vertebrata Cret. Form. West, Kept. U. S. Geol. Surv. Territ., vol. ii,1875, p. 280. 112 SYSTEMATIC PALEOXTOLOGY form extant. The Tertiary caudal fans which have been theoretically associated with the teeth of Isclujrliiza by Cope and Clark are here con- sidered to belong to typical Sword-fishes. The following species is the only one known to occur in Maryland. XiPHiAS (?) RADIATA (Clark). Plate XII, Fig. 8. Ischyrhizai?) racliata Clark, 189.5, Johns Hopkins Univ. Circ., vol. xv, p. 4. IschyrMza (?) radiata Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 60, pi. vii, fig. 2a (? non figs. 26, 2c). Description . — Terminal vertebral centrum deeply concave in front and circular in cross-section, its neural and haemal spines fused into a solid fan-shaped body; the anterior haemal spine less completely fused with the next following than are all the rest, and even separated from it near the point of attachment with the centrum by a small perforation passing completely through the fan. [Dentition and other parts of the skeleton unknown.] This species is established on a unique fan-shaped body, the extreme height of which is 3.9 cm.; hut some of the South Carolina specimens exceed 10 cm. The latter also differ from the Maryland form in having the vertebral centrum transversely elongated instead of circular. The type is a hypural fan in the Museum of Johns Hopkins Uni- versity. Occurrence. — Aquia Formatiox. Clifton Beach. Collection . — Johns Hopkins University. Genus PHYLLODUS Agassiz. The presence of this interesting genus in North America was first made known by Dr. Jeffries Wyman," who came into possession of two unique dental plates from the Eocene of Eichmond, Virginia. Eather poorly executed woodcuts of both specimens are given by him, the more perfect one being compared with P. toliapicus Agassiz, and the other declared to he different from any described species. This paper of Wy- man’s seems to have escaped general notice, and was certainly over- looked by Marsh, when in 1870 he claimed his P. elegans and P. curvi- 1 Amer. Jour. Sci., ser. ii, vol. x, 18.50, p. 284. 2 Proc. Amer. Assoc. Adv. Sci., 18th Meet., 1870, p. 228. MARYLAND GEOLOGICAL SURVEA' 113 dens, likewise founded on unique dental plates from the Eocene and Miocene respectively of New Jersey, to he the first indications of this genus in North America. Neither of the last two species have been figured, hut it is probable from Marsh’s brief description that P . elegcins is a young example of P. toliapicus. Furthermore, it is practically cer- tain that neither of AYyman’s specimens are referable to P. toliapicus, but each is representative of a distinct species. Whether their horizon is Eocene or Miocene was not conclusively determined by Wyman, although the chances are in favor of attributing them to the former. Traces of this genus have not as yet been discovered in Maryland, but the following species deserves notice on account of its historical and scientific interest. Phyllodus hipparioxyx n. sp. Phyllodiui sp. aflF. toliapicus Wyman, 1850, Amer. Jour. Sci., ser. ii, vol. x, p. 234, woodc. fig:. 9rt. Type . — Detached dental plate; formerly in Museum of Comparative Zoology, Cambridge, Mass. OTOLITES. Plate XII, Figs. 4-6. Fish otolites, or ear-stones,’’ are found almost exclusively in the detached condition, this being due to the fact that they are held in place during life only by membranes, and hence readily fall out from the head and sink to the bottom while the decomposing body of the fish continues to float on the surface, a prey to all sorts of creatures, or is cast ashore by the waves. The circumstance of large numbers of fossil fish skeletons being found in close proximity to one another, but none of them having otolites preserved in situ, is cited as an argument against their having met their death suddenly or in shoals. The peculiar struc- ture and composition of otolites favor their preservation in the fossil state, hence it is not surprising that they sliould occur in considerable abundance and variety throughout the Tertiary and even older horizons. Eather is it the converse proposition which excites wonder; for when we consider the number of forms represented solely by ear-bones, it is diffi- cult to understand why not a vestige of other parts of the skeleton re- mains, s 114 SYSTEMATIC PALEONTOLOGY The otolites of Cyclostomes and cartilaginous fishes consist of irregu- lar and loosely united aggregations of lime carbonate; those of Teleos- tomes, on the other hand, are dense porcellanous bodies composed of microscopic crystals of calcite, excellently adapted for fossilization. The proportion of calcite frequently amounts to 98 per cent of the whole, and the organic matter rarely exceeds 4 per cent. Although extremely variable in form and size, nothing can be predicated from these char- acters as to the proportions of the complete fish. The sculpturing of tiie external surface, however, has been found fairly distinctive for cer- tain families; for instance, it is more or less tuberculose among the Gadidae, Sciaenidae, etc,, and radially folded among the Pekcidae and Spaeidae. Otolites are secreted in a few definite regions of the auditory appa- ratus. A small one, termed by Koken the lapillus, is formed in a por- tion of the labyrinth known as the vestibule ’’ or utriculus; another {asteriscus of Koken) occurs in the posterior prolongation of the otolite- sac (sacculus), and the principal ear-stone in the center of the sac proper. The principal otolite (sagitta of Koken) occupies a constant position with reference to the investing sacculus, partaking of its shape and being attached to its inner wall; and accordingly it is capable of being precisely oriented, even when found in the detached fossil condition. That is to say, a dorsal and ventral, anterior and posterior, and inner and outer side are almost always to be recognized, as well as the side of the head to which it belongs. But on the other hand the configuration, and in the opinion of some excellent authorities, even the surface mark- ings of fish otolites are dependent on the variable form of the enclosing membranous sac, and are by no means constant within specific or even generic limits.^ 1 “ Hasse halt auch die Form der Otolithen fiir onvvichtig, als ein mit der Form des Sacculus sich anderndes Moment. . . . Die Gestalt der Otolithen ist allerdin^s in ^ewissen Grenzen variabel, in Zusammeuhange mit den individuelleu Schwankunj^en der Sacculus-Form, welcher sie sich anpasst. Audi ist das Wachsthum vorwieg:end auf die aussere Seite anjj^evviesen, welche frei im Sacculus liegt ; .... dementsprechend ist das Wachsthum der iiusseren Seite unregelmassiger, uud gerade die auf die Scul])tur derselben sich griindenden Merkmale . . . erwiesen sich ofters als ungeeignet, well sie sich durch Vergrosserung des Gehorsteines zu leicht verwischen.” — E. Koken, Ueber Fisch-Otolithen etc. {Zeitschr. d. d. geol. Ges., vol. xxxvi, 1SS4, p. 51S). MARYLAND GEOLOGICAL SURVEY 115 Xevertlieless, the structure and topography of these minute and ap- parently insignificant bodies have been investigated with great care, and a precise nomenclature established. For the depression extending from the anterior margin backward in a horizontal direction on the flat or concave inner side, Koken has proposed the designation of sulcus acusti- cus, and this he regards as furnishing the most important diagnostic characters. The sculpture of the inner and outer sides, and nature of the peripheral border, whether sharp or thickened, smooth, folded, den- ticulated or incised, and various minor characters of like nature are all taken into account in the attempt to identify detached specimens. Their size, too, is held to be an important distinguishing character. The most painstaking investigations on fossil otolites from both our own and European Tertiaries are those of Professor Koken," and refer- ence should be had to his writings by all interested in this snbject. A summary of the earlier literature is given by him in the first paper cited below. If any are inclined to question the accuracy of his determina- tions of genera and species, the opportunity is certainly open for more extended comparisons with recent and fossil forms. Otolites occur rather frequently in the Eocene of Maryland, but only a few have been found in the Miocene at Plum Point. A few typical examples are shown in Plate XII, Figs. 4-G, but further than to say that they bear a general resemblance to those of the Gadidae, their identi- fication is not attempted here. Occurrence. — Xanjemoy Formation. Port Tobacco, 2^ miles above Popes Creek, Woodstock. Collection . — IMaryland Geological Survey. COPROLITES. Polled cylindrical bodies of amorphous structure and very suggestive of fossil fish excrement are occasionally found at a few localities in the Eocene of IMaryland and Virginia. Tlie occurrence of coprolites of enor- mous size in the Miocene of Virginia has been known for a long time." Lor., rlt., pp. 500-565. — Neue Untersucliungen an tertiaren Fisch-Otolithen, vol. xl, 1888, pp. 274-805. Wyman, Notice of Remains of Vertebrated Animals found at Richmond, Virginia, Amer. Jour. Sci., ser. ii, vol. x, 1850, p. 285. 116 SYSTEMATIC TALEOXTOLOGY ARTHROPODA. Class CRUSTACEA. Superorder M ALACOSTR ACA. Order DECAPODA. Family CANCROIDEA. Description . — Claws belonging to an indeterminate genus of the Cancroidea are abundant in the bed underlying the indurated ledge at Upper Marlboro. All of the specimens are so fragmentary that no attempt is made to illustrate the forms. Collection . — Maryland Geological Survey. Superorder OSTRACODA. Family BAIRDIIDAE. Genus BYTHOCYPRIS Brady. Bythocitpeis subaequata n. sp. Plate XVI, Pigs. 1-4. Description . — Carapace about 1.0 mm. in length, elongate, snbcylin- drical or, perhaps better, siibreniform, the dorsal outline arcuate, the ventral slightly hollowed, and the ends rounded and nearly equal, the posterior a trifle blunter than the anterior; end view nearly circular, dorsal and ventral views lanceolate, with the greatest thickness about the middle of the posterior half; left valve slightly overlapping the right along its ventral edge; surface smooth or very finely granulose. Inner side of valves with simple thin edges, and within these, except along the dorsal border, a thin bevelled plate, mnch the widest an- teriorly. There are numerous fossil and recent Ostracoda, mostly of otherwise widely diverging genera, that have a carapace similar to this, but nom^ was found exactly matching it. MAKYLAXD GEOLOGICAL SURVEY 117 Occurrence . — Aquia Formatiox. Upper Marlboro. Collection . — Maryland Geological Survey. Bythocypris parilis n. sp. Plate XVI, Figs. 5-8. Description . — Carapace about 1.0 mm. long, and nearly or quite 0.5 mm. high; reniform, strongly arched dorsally, very slightly sinuate or straight in the ventral portion of the outline, and with the ends rounded and very nearly equal, the posterior outline however being usually a trifle oblique above, and the turn into the basal line slightly lower than at the front end; point of greatest thickness above the middle, the slope toward the ventral edge being flatter than elsewhere; edge view elongate, snbelliptical, the anterior extremity more acute than the posterior, the latter being comparatively blunt. Left valve slightly overlapping the right both above and below, its ventral edge somewhat thickened in the middle and bordered along the anterior and posterior thirds of its extent by a sharply impressed, thin line. Surface generally appearing quite smooth, but under favorable circumstances very small scattered pnnctae may be observed. Interior of valves with the marginal plate well de- veloped and widest in front. This carapace is relatively higher, has a more arcuate back, and less acute anterior extremity (in edge view) than its associate B. subaequata. It is distinguished further by the dorsal overlap of the valves and in the greater development of the internal marginal plate. Occurrence . — Aquia Formatiox. Upper Marlboro. Collection . — Maryland Geological Survey. Family CYTHERELLIDAE. Genus CYTHERELLA Jones. Cytherella marlboroexsis n. sp. Plate XVI, Figs. 9-13. Description . — Carapace nearly regularly ovate, the height and length about as two is to three; 0.9 or 1.0 mm. in length; ventral portion of outline somewhat less convex than the dorsal. Eight valve much larger than the left and projecting beyond it all around. Edge view obtusely lanceolate, with both extremities blunt, the posterior, the more so, and 118 SYSTEMATIC PALEONTOLOGY much thicker than the other; end view snhovate. Valves eompara- tively thin for this genus, the marginal groove of the right valve rela- tively narrow though sharply defined. Interior of right valve with two snhovate smooth spaces, situated one in the anterior, the other in the posterior half, and around them concentric rows of small pnstnles. Sur- face smooth or minutely punctate. No known Tertiary species agrees very closely with this. The well- known C. compressa (Miinster), has a similar edge view, as have also several other species, hnt otherwise, the form of its carapace, especially the ventral portion of the outline, is quite different. The Cretaceous C. ovata is probably a closer relative but differs obviously in its edge and end views. Occurrence . — Aquia Foemation. Tipper Marlboro. Collection . — Maryland Geological Survey. Cytiierella submarginata n. sp. Plate XVI, Figs. 14, 15. Description . — Carapace about 1.0 mm. in length, somewhat oblong, rounded at the ends, the posterior end a little wider and its margin more oblique above and merging more gradually into the very slightly arcuate dorsal outline than the anterior; ventral margin straight, edge view subcuneiform, end view subovate. Valves compressed convex, thickest posteriorly, with an obscurely defined broad depression near the midlength and mostly above the center of the valves. A narrow but distinct rim borders the two ends. Surface smooth. Of this species only the single valve figured has been seen. Com- pared with described species it was found to agree rather well with C. londinensis Jones a Lower Eocene species from London, Eng., but after a closer examination it was decided that it could not be justly referred to that species. As described and figured C. londinensis must have quite a different appearance in edge views, due to the more uniform convexity of its valves. The central depression and marginal rims as well as its different outline, will serve to distinguish C. submarginata at once from C. marlhoroensis with which it is associated. Occurrence . — Aquia Formation. Upper Marlboro. Collection . — Maryland Geological Survey. MARYLAND GEOLOGICAL SURVEY" 119 Family CYTHERIDAE. Genus CYTHERE Muller. Cytpiere marylandica n. sp. Plate XVI, l"igs. 16-18. Description. — Carapace about 1.0 mm. in length and 0.55 mm. in height and thickness, suhovate in outline; hinge straight, half the en- tire length of carapace, ventral outline broadly arcuate; anterior end obliquely rounded, most prominent in the lower half and much wider than the posterior end; the latter is neatly rounded below, obtusely angu- lar above the middle, then straight or slightly sinuate to the subangular extremity of the hinge line. Valves unequal, the left overlapping the right, very convex and swollen in the middle and thickest near the ventral edge. The swollen region of the valves is of subtriangular shape and sharply defined Avhere it rises from the relatively small, compressed, terminal remnants of the surface. Of these remnants the posterior is more depressed (it may appear like a flattened border) and narrower than the anterior one, and both are marked with shallow pits arranged in rather obscure concentric series. The surface of the swollen region is more distinctly pitted, Avith the pits arranged in the loAver half betAveen more or less sharp longitudinal curved riblets and much less regularly in the upper half. Sometimes the SAvelling is terminated beloAv by one or tAvo ribs more prominent and stronger than the rest. Edge Anew snbovate, Avith the ends produced; end vieAV subtriangular AAuth the lat- eral lines rather strongly convex. Hingement consists as usual in Cythere of large lateral teeth and connecting har. This seems to be a Avell-marked species Avith not very close relations to C. trigonula Jones and C. triangularis (Peuss) Jones. From lioth it differs in outline, the former, varying further in, having also a finer surface punctation, a much more triangular end vieAV, and relatively very slightly compressed ends causing the edge vieAv to he equally dif- ferent. C. triangularis agrees better in end and edge vieA\"s but its sur- face differs decidedly, being smooth, shining, and beset Avith scattered setae.’’ Another of the species described by Jones in his Monograph of the Tertiary Entomostraca of Ehigland, es])ecially since he nuoitions that he has a scarcely distinguishable A-ariety of it from the middle Ter- 120 SYSTEMATIC PALEONTOLOGY tiary of Maryland, may be compared with C. marylandica. This is Cythere pmictata (Miinster). Judging from illustrations alone the pres- ent species must be quite distinct and so obviously that it seems highly improbable that the American variety of Munster’s species mentioned by Jones, is the same as the one above described. Occurrence. — Aquia Fokmation. Upper Marlboro, Brooks Estate near Seat Pleasant. Collection. — Maryland Geological Survey. Genus CYTHEREIS Jones. Cytheeeis bassleri n. sp. Plate XVI, Figs. 19-21. Description. — Carapace oblong, length 0.80 to 0.85 mm., widest and rounded anteriorly; the posterior edge more or less angular in the mid- dle, straight or slightly sinuate above to the angular extremity of the hinge, and with two or three spines projecting from the slightly convex, lower half; edges with a thickened rounded rim, becoming obsolete near the center of the flattened ventral region; hinge line straight except at the antero-cardinal angle which is thickened and prominent; ventral outline slightly sinuate. Valves equal, with a rounded sub-central node, sometimes obscured by a network of small ridges, and a sharp ventral ridge rising gradually from its inception at the antero-ventral angle and ceasing abruptly at a point about one-fourth of the length of the valve from its posterior extremity. A less prominent ridge runs from the high end of the ventral ridge in a slightly oblique direction to the post- cardinal angle and then turns forward. The whole surface is covered with rather large pits arranged in more or less irregular curved series, the space between the rows, especially over the central portion of the valves being raised into thin and sometimes coalescing ridges. This species presents more or less close affinities with no less than six of the species of Cythere figured by Bosquet in his excellent Mono- graph of the Ostracoda of the Tertiary deposits of France.^ These are C. hehertiaiia Bosq., C. thierensiana Bosq., C. desliayesiana Bosq., C. ’ Desc. des Entomostrace’s Fossiles des Terrains Tertiaires de la France et de la Belgique. Mem. Couron. Acad. Belg., Tome xxiv, 1851. MARYLAND GEOLOGICAL SURVEY 121 angusticostaia Bosq., C. macropora Bosq. and C. edwardsi (Roemer), all Eocene species except the last, which is a widely distributed Miocene fossil. Despite the often striking similarities presented, not one of the European species mentioned agrees closely enough in all respects to justify a reference of the Maryland form to it. Cytliereis hassleri, which I name in honor of my able and indefatigable assistant, Mr. R. S. Bassler, seems to be a common fossil at Dpper Marl- boro. Considering that the specimens studied present considerable variation in surface sculpture, it is possible that they represent more than a single specific type. I have also a specimen from the Cretaceous at Vincentown, N”. J., which can scarcely be distinguished from the Upper Marlboro specimen figured. Occurrence . — x\quia Formation. Upper Marlboro. Collection. — Maryland Geological Survey. Genus CYTHERIDEA Bosquet. Cytheridea perarcUx\.ta n. sp. Plate XVI, Fig. 22, 23. Description. — Carapace 1.1 mm. long, 0.6 mm. high, strongly and, ex- cepting the acuminate posterior extremity, rather uniformly convex, obliquely acute-ovate in outline; ventral edge straight to the acute pos- terior extremity, the sharpness of which is emphasized by a small spine; anterior outline wide and regularly rounded, and armed with five or six spines; dorsal side strongly arcuate, the curve straightening some- what as it nears the posterior end. Central portion of surface, over a space corresponding in shape with the outline of the valves, marked with eleven or twelve approximately vertical furrows, each including a row of small punctures. Beyond this space the surface is smooth, ex- cepting toward the posterior end where an obscurely wrinkled appearance may be observed. Ventral edge of right valve with a narrow bevel in- ward. Hinge as required by the genus, consisting of a series of small denticles at each end of the hinge in right valve and corresponding sockets in the left valve. Edge view broadly lanceolate, thickest near the middle length and slightly more attenuate behind than in front; end view subcircular. 122 SYSTEMATIC PALEONTOLOGA" At first it was believed that this form might he regarded as a variety of Cytheridea mulleri (Miinster), a common and widely distributed European Tertiary and Becent species. However a more careful com- parison brought out so many differences that it seemed best to rank them as distinct species. This conclusion was confirmed by finding almost unquestionable C. mulleri associated with C. perarcuata at Woodstock, while C, intermedia (Reuss) which Jones considers a close variety of C. mulleri, was found rather abundantly in association with specimens agreeing closely with Jones’ C. deUlis, at Upper Marlboro. C. perarcu- ata differs from all of these forms in the restricted extent of its surface markings, in wanting a mesial furrow, in its relatively greater height and more strongly arcuate dorsal outline. Its edge view furthermore is decidedly different, the central portion being thicker, while the ends, the posterior especiall}q are thinner. Occurrence. — Nanjemoa^ Formation. AVoodstock. Aquia Forma- tion. Potomac Creek. Collection. — Maryland Geological Survey. MOLLUSCA. Class CEPHALOPODA. Subclass TETRABRANCHIATA. Order NAUTILOIDEA. Suborder ORTHOCHAENITES. Family CLYDONAUTILIDAE. Genus HERCOGLOSSA Conrad. IIercoglossa tuomeam n. sp. Plates XVII-XIX. NautiluH ,sp. Tuomey, 1842, Amer. Jour. Sci., vol. xliii, p. 187. Nautilus sp. Clark, 1895, Johns Hopkins Univ. Circ., A"o1. xv, p. 4. Nautilus sp. Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 63, pi. ix, tig. 1. Description . — Shell large; aperture v'ide, narrowing rapidly, without curving to a narrow and sharply rounded periphery; ventral saddles of MARYLAND GEOLOGICAL SURVEY 123 moderate size; lateral lobes regularly but moderately rounded; lateral saddles narrower and sharper than the other saddles; umbilici not small; shell thick (2-8 mm.), marked by fine, distinct, closely-set lines of growth, which sweep shar])ly back on the periphery. This species is distinguished from If. (E nclimatoceras) ulriclii by its much less prominent ventral saddles, and by its less uniformly rounded transverse section, the sides being almost without curvature down almost to the very periphery. The nautiloid shell which Tuomey roughly described without naming was from the James river and from a horizon exactly corresponding to our Popes Creek occurrence. There is little doubt that it was this species. Diameter (restored) of coil of largest specimen about 400 mm. Occurrence. — Xaxjemoy Formation. Popes Creek (abundant). Aquia Formation. Clifton Beach (fragments rare). Collections . — Maryland Geological Survey, Johns Hopkins University. Class GASTROPODA. Order OPISTHOBRANCHIATA. Suborder TECTIBRANCHIATA. Family ACTAEONIDAE. Genus TORNATELLAEA Conrad. Tornatellaea BELLA Coiirad. Plate XX, Figs. 1, la, 2. Tornatellaea bella Conrad, 1860, Jour. Acad. Nat. Sci. Phila., 2nd ser., vol. iv, p. 294, pi. xlvii, tig. 23. Tornatella bella Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 4. Tornatella bella Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 63. Description. — Ovate, spire conical; revolving lines numerous, im- pressed, punctate striate.” Conrad, 18G0. Shell solid, ovate in profile, six-whorled; surface with uniform, punc- tate, spiral grooves, crossed only by lines of growth and regularly un- 124-. SYSTEMATIC PALEOXTOLOGY diilating in width; spire short, conical, acuminate; whorls slightly con- vex; body whorl more than half the length of the shell, moderately convex; suture distinct; outer lip sometimes crenulate; columella with two pronounced oblique plicae. Length, 15 mm.; width, 8 mm. Occurrence. — Xaxjemoy Foematiox. West of Port Tobacco. Wood- stock, 1 mile southeast of Piscataway. Aquia Foematiox. Aquia Creek, Potomac Creek, 1 mile northeast of Piscataway, Upper Marlboro. Collections . — Maryland Geological Survey, Philadelphia Academy of Natural Sciences, U. S. National Museum. Family RINGICULIDAE. Genus RINGICULA Deshayes. Eixgicula dalli Clark. Plate XN, Figs. 3, 3a. Ringicula dalU Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 4. Ringicula dalli Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 64, pi. ix, figs. 3a, 36. Ringicula dalli Aldrich, 1897, Bull. Amer. Pal. No. 8, p. 8, pi. ii, fig. 6. Description . — Shell small, five-whorled; surface of last four whorls strongly striate spirally; spire elevated, acuminate; body whorl much inflated; outer lip much thickened and crenulate within; columella with thick callous and with two strong plaits.’’ Clark, 1896. Length, 3 mm.; width, 2 mm. Occurrence. — Nax.temoy Foematiox. IVoodstock. Collection . — Maryland Geological Survey. Family SCAPHANDRIDAE. Genus CYLICHNA Loven. Cylichna vexusta Clark. Plate NX, Figs. 4, 4a. Cylichna vemu^ta Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 4. Cijlichna vemisia Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 64, pl.'ix, figs. 2a, 26. Description . — “ Shell small, elongate-ovate, rather globose; surface spirally striate; spire depressed; columella with small obscure plait.” Clark, 1896. MARYLAND GEOLOGICAL SURVEY 125 The spire is usually perforate, and the revolving lines alternate and punctate. It most closely resembles C. aldrichi Langdon, from which it is distinguished by being proportionally longer, less cylindrical in out- line, and with the spire less strongly perforate. Length, 7 mm.; width, 3.5 mm. Occurrence . — Xanjemoy Formation. West of Port Tobacco, Head of Xanjemoy Creek, Woodstock. Aquia Formation. 1 mile southeast of Mason Springs, Potomac Creek, 2 miles below Potomac Creek, 1 mile northeast of Piscataway, Clifton Beach. Collections . — Johns Hopkins University, ]\raryland Geological Survey. Superfamily TOXOGLOSSA. Family PLEUROTOMIDAE. Genus PLEUR.OTOMA Lamarck. Pleurotoma harrisi Clark. Plate XX, Figs. 5, 5a, 6. Tleurotoma harrin Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 4. Pleurotoma harrisi Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 64, pi. ix, figs. 4a, 4&. Descri])tion . — Shell of moderate size, elongate, five or six whorled; surface with distinct, revolving lines of varying size, crossed by trans- verse ridges; aperture narrow, with long straight canal.’’ Clark, 1896. The lower half of the whorl is strongly convex and is strongly orna- mented with 'revolving lines, alternating in size, and is crossed on the shoulder by oblique nodular ridges. The upper half of the whorl is flat, with very faint revolving lines, except one or two strong ones about the middle of the flat zone. The aperture narrows rapidly toward the base, the body whorl partaking of the constriction. The canal is very long, straight, and narrow. Length, 30 mm.; width, 8 mm. Occurrence . — Aquia Formation. Potomac Creek, 2 miles below Po- tomac Creek, 1 mile southeast of Mason Springs. Collection . — Maryland Geological Survey. 126 SYSTEMATIC PALEOXTOLOGY Pleueotoma potomacexsis n. sp. Plate XX, Figs. 7, 7a. Description . — Shell attenuate, with spire and beak of equal length; aperture narrow; beak long and straight; whorls seven, with four more in the nnclens; few large, raised, revolving lines on and below the shoul- ders; nnmerons fine, proximate lines between these, and covering the entire whorl; two ])rominent, raised, revolving lines below the sntnre, the lower more prominent; shoidder with acnte nodes, carinated by one or two of the major revolving lines; lines of growth faint. Some varieties of P. nasnta Whitfield are very similar to this species. It is intermediate between that species and P. harrisi Clark. Length, 31 mm.; width, 8 mm. Occurrence. — Aquia Fokmatiox. 1 mile northeast of Piscataway, 2 miles below Potomac Creek. Collection. — ]\Iar3dand Geological Survey. Pleueotoma ducateli n. sp. Plate XX, Fig. 8. Description . — Surface smooth, save for faint, impressed, revolving lines which become stronger just below the sntnre, and very strong on the beak; sntnre very distinct; columella straight, striated spirally; lines of growth faint, with broad sinus below the sntnre. Length, 10 mm.; width, 4 mm. Occurrence. — Aquia Foematiox. 1 mile southeast of Mason Springs. Collection . — IMaryland Geological Survey. Pleueotoma ta'soxi n. sp. Plate XX, Fig. 0. Description . — Shell eight-whorled; body whorl about half the length of shell; month contracting but slightly toward beak; body whorl with sixteen, oblique, longitudinal ribs, strongly nodular where crossed by the large, elevated, revolving lines; eight strong, revolving lines on the body whorl helow the shoulder, and nnmerons fainter ones below, on the beak. All the whorls are concave above the shoulder, and nnscnlptnred, save for lines of growth and for a strong, raised, nodular, snbsntnral MARYLAND GEOLOGICAL SURVEY 127 line. Whorls of the spire with four nodular revolving lines below the shoulder. Length, 12 mm.; width, -1 mm. Occurrence. — Aquia Formation. 1 mile southeast of Mason Springs. Collection . — Maryland Geological Survey. Subgenus HEMIPLEUROTOMA Cossmann. Pleurotoma (Hemipleurotoma) childreni Lea. Plate XX, Figs. 10, 11. Pleurotoma childreni Lea, 1833, Contrib. to GeoL, p. 137, pi. iv, fig. 132. Pleurotoma denticula var Harris, 1899, Bull. Amer. Pal., No. 11, p. 12, pi. i, figs. 21 , 22 . Description . — Shell fusiform, tiirrited, transversely striate, granu- late on the larger part of the whorl; substance of the shell rather thick; spire elevated, obtuse at apex; whorls about nine, siibcanaliciilate above; mouth long and narrow, one-third the length of the shell.” Lea, 1833. Our specimens vary considerably in the smaller details of sculpture, but all seem to fall within the limits of variation of the Alabama form. Whether they are the same as the French species P. denticula Bast, to which Professor Harris assigns the Alabama form is a question that cannot be settled here. They agree with it well enough to fall into the subgenus Hemipleurotoma of which P. denticula is the type. Length, 12 mm.; width, 3.5 mm. Occurrence. — Aquia Formation. 1 mile southeast of Mason Springs, 2 miles below Potomac Creek. Collection . — Maryland Geological Survey. Pleurotoma piscatavensis n. sp. Plate XX, Fig. 12. Description . — Shell fusiform, seven-whorled, carinated; lines of growth distinct; revolving lines absent above the shoulder, one to three in num- ber below the shoulder; beak marked only by lines of growth; nucleus three-whorled, smooth; following whorls of the spire with oblique ])li- cae, extending from suture to suture; body whorl with about ten acute nodes, confined to the suture. 128 SYSTEMATIC PALEOXTOLOGA' Length, 11 mm.; width, 4 mm. Occurrence. — Aquia Foematiox. 1 mile northeast of Piscataway. Collection . — Maryland Geological Survey. Genus MANGILIA Risso. Subgenus PLEUROTOMELLA Venill. Maxgilia (Pleurotomella) bellistriata Clark. Plate XX, Figs. 13, 13a. Mangilia {Fletirotomella) bellistriata Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 4. Mangilia {Pleurotomella) bellistriata Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 65, pi. ix, flg. 5. Description . — Shell small, snhfnsiform, with a rather short, pointed spire, and ahont five whorls; body whorl large, somewhat infiated; earlier whorls nearly flat; surface scnlptnred with numerous, alternating, larger and smaller spiral threads, crossed hy fine, wavy lines, and by irregu- larly spaced, oblique ribs, about twenty in number on the body whorl; ribs strongest at the shoulder, gradually disappearing both posteriorly and anteriorly; behind the shoulder somewhat excavated; aperture nar- row.^’ Clark, 1896. There is a distinct fold on the columella, and the lines of growth are very slightly curved. Length, 27 mm. (restored); width, 13 mm. Occurrence. — Xaxjemoy Foematiox. Popes Creek. Aquia Forma- tiox. Potomac Creek. Collections . — Johns Hopkins University, Philadelphia Academy of Xatural Sciences. Family CANCELLARIDAE. Genus CANCELLARIA Lamarck. Caxcellaria graciloides Aldrich, var. Plate XXI, Fig. 1. Caiicellaria graciloides Aldrich, 1898, The Nautilus, vol. xi, p. 98. Cancellaria graciloides 1899, Bull. Amer. Pal., No. 11, pp. 28, 29, pi. iii, tigs. 10, 11. Description . — Shell broadly fusiform, spire elevated, whorls 6-7, rounded, slightly shouldered, cancellated, first three smooth, on the MARYLAND GEOLOGICAL SURVEY 129 other^ the revolving lines are nnmerons, strongly defined; lines of growth smaller and much finer than the revolving lines, sntnre deeply im- pressed, outer lip expanded, strongly nodular within, columella with three folds, aperture pointed and canaliculate at base/^ Aldrich, 1898, This abundant and variable form approaches too near to some va- rieties of C. graciloides to be safely separated from it. Length, 13 mm.; width, 8 mm. Occurrence . — A quia Formation. 1 mile southeast of Mason Springs. Collection. — Maryland Geological Survey. Cancell ARIA sp. Plate XXI, Fig. 2. Several specimens of Cancellaria were found that are so imperfect and immature, that it is unsafe to describe them or even to refer them to any known species, yet they are very different from our other Maryland species. The figured specimen represents a form from the locality two miles below Potomac Creek which also doubtfully occurs at Potomac Creek, and which distantly recalls C. parva Lea.^ When .the adult is found it will probably be recognized as a new species. Another form from Potomac Creek may be C. ulmula Harris^ or a variety. This is so imperfect that it does not seem desirable to figure it. Occurrence . — Aquia Formation. 2 miles below Potomac Creek, Po- tomac Creek. Collection . — Maryland Geological S'urvey. Subgenus NARONA H. and A. Adams. Cancellaria (Xarona) potomacensis n. sp. Plate XXI, Figs, 3, 3a. Description . — Shell elongate; mouth more than half the length of the shell; spire short; whorls marked with distinct, raised, flat-topped, re- volving ridges, with interspaces twice as broad; body whorl with twenty of these ridges, whorls of the spire with six. Lines of growth and ^Contrib. Geol., p. 42, pi. v, fig. 141. 2Proc. Acad. Nat. Sci. Phila., vol. xlvii, 1895, p. 66, pi. vi, fig. 6. 130 SYSTEMATIC PALEONTOLOGY several variable, usually obscure, longitudinal undulations cross the revolving ribs, granulating them and often reticulating the surface. Labium expanded, grooved and cancellated. Labium with two, distinct, oblique folds and numerous striae, continuations of the external revolv- ing lines. Canal short, recurved. Length, 17 mm.; width, 8 mm. Occurrence . — Aquia Fokmation. 1 mile southeast of Mason Springs. Collection . — Maryland Geological Survey. Superfamily RACHIGLOSSA. Family OLIVIDAE. Genus OLIVULA Harris. Olivula sp. A single specimen was found which gives little doubt of its generic character. It is probably distinct from 0. staminea (Conrad). In the imperfect condition of the specimen it is impossible to assign it to any species, new or old, and a figure would show no determining characters. Length, 20 mm.; width, 6 mm. Occurrence . — Nanjemoy Fokmation. Popes Creek. Collection . — Maryland Geological Survey. Family VOLUTIDAE. Genus VOLUTILITHES Swainson. VoLUTiLiTHES PETROSUS (Conrad). Plate XXI, Figs. 4, 5, 5a. Valuta petrosa Conrad, 1838, Fossil Shells of the Tertiary, No. 3 [1st Edit.], p. 29. Valuta petrosa Conrad, 1835, Fossil Shells of the Tertiary, No. 3 [2nd Edit.], p. 41, pi. xvi, fig. 2. Atlileta tuomeyi Conrad, 1853, Proc. Acad. Nat. Sci. Phila., vol. vi, p. 449. Valutilithes {Athleta) tuomeyi Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 4. Volutilithes {Athleta) tuomeyi Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 65, pi. x, figs, la, 15. Description . — “ Shell subglabrous; body whorl marked with from eight to ten longitudinal folds, terminating on the shoulder in compressed MARYLAND GEOLOGICA,!^ SURVEY 131 subacute tubercles, which are also distinct on the spire: transversely striated at base: two folds on the columella/^ Conrad, 1833. The Maryland specimens are principally of the tuomeyi type, but the normal form occurs with it at most localities. Length, 38 mm.; width, 25 mm. Occurrence. — Xaxjemov: Formation. Woodstock, Popes Creek; West of Port Tobacco. Aquia Formation. Potomac Creek, 2 miles b^low Potomac Creek, 1 mile northeast of Piscataway, 1 mile southeast of Mason Springs, Aquia Creek. Collections. — ]\Iaryland Geological Survey, Johns Hopkins University, Philadelphia Academy of Xatural Sciences, U. S. Xational Museum. VOLUTILITHES Sp. Plate XXI, Figs. 6, 6a. Volutilithes sp. Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 4. Volutilithes sp. Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 65, pi. x, figs. 2a, 25. A fine cast of a large species of Volutilithes was obtained from the in- durated ledge. Zone 3, at the Aquia Creek bluffs, and a very imperfect specimen from Potomac Creek. It is unlike any of the species of Volu- tilithes hitherto described, but from the fact that the shell subatance is almost lacking no attempt will be made to give a full description. It has a somewhat compressed form, due to pressure. The shell substance is extremely thin, and the surface is marked only by lines of growth. The tubercles are obtuse and distant, and the spire small. Length, 75 mm.; width, 53 mm. Occurrence. — Aquia Formation. Aquia Creek, Potomac Creek. Collections. — Maryland Geological Survey, Johns Hopkins University. Genus CARICELLA Conrad. Caricella pyruloides (?) (Conrad). Plate XXI, Figs. 7, 8. Turhinella pyruloides Conrad, 1833, Fossil Shells of the Tertiary, No. 2, p. 24, pi. x, fig. 1. (?) Caricella sp. Clark, 189.5, Johns Hopkins Univ. Circ., vol. xv, p. 4. (?) Caricella sp. Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 66, pi. xi, fig. 1. 132 SYSTEMATIC PALEONTOLOGY Description . — Pyriform, ventricose, smooth; with obscure spiral striae on the inferior half of the body whorl; spire very short; apex slightly mammillated; columella with 4 distant oblique plaits/’ Con- rad, 1833. The specimens which are referred to this species consist of the cast and the broken shell which are figured, and a still more imperfect cast. It is not certain that they belong to the same species, or that any of them belong to the species to which they are here referred. If they do not belong here they probably represent one or more undescrihed species. Length, 55 mm.; width, 22 mm. Occurrence . — Aquia Formation. Potomac Creek, Aquia Creek, Liv- erpool Point. Collections . — Maryland Geological Survey, Johns Hopkins University. Genus MITRA Lamarck. Mitra marylandica Clark. Plate XXI, Figs. 9, 9a. Mitra marylandica Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 4. Mitra marylandica Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 66, pi. xi, figs. 4a, 45 (not 3). Description. — Shell small, rather thick, with six (?) whorls; surface with numerous, thickly-set spiral threads, crossed by fine wavy lines, giving a finely reticulated appearance; spine moderately high; suture distinct, appressed; shoulder not prominent; aperture elongated; col- umella nearly straight, with three plaits.” Clark, 1896. The essential character which distinguishes this species from the fol- lowing is the lack of ribbing. Length, 21 mm.; width, 7 mm. Occurrence . — Aquia Formation. Pomonkey Xeck. Collection . — U. S. Xational Museum. Mitra pomonkensis n. sp. Plate XXI, Figs. 10, 10a. Mitra sp. Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 4. 3Iitra sp. Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 66, pi. xi, figs. 3a, 36. Description . — Shell larger than M. marylandica; whorls strongly con- vex, and with a somewhat angulated shoulder slightly above the middle; MAEYLAND GEOLOGICAL SURVEY 133 sculptured by numerous, approximate, impressed, revolving lines, and variable longitudinal ribs, which stop at the shoulder, leaving a subsu- tural constriction above it. The best specimens of this species are in the Philadelphia Academy and are from Potomac Creek. The type in the U. S. National IMuseum is now labelled ^^‘Near Month of Potomac Cr.f G. D. Harris,’^ but it was supposed when des- cribed to have come from Pomonkey Neck. Length, 25 mm.; width, 9 mm. The largest specimen has width of 12 mm. Occurrence. — Aquia PormaIion. Pomonkey Neck, 2 miles below Po- tomac Creek, Potomac Creek, 1 mile northeast of Piscataway. Collections. — Maryland Geological Survey, U. S. National Museum, Philadelphia Academy of Natural Sciences. Mitra potomacensis n. sp. Plate XXI, Fig. 11. Description. — Shell small; whorls but slightly convex, and not con- stricted below the suture; revolving lines fine, distinct; ribs reaching from suture to suture, and often extending in one continuous line from w^horl to whorl; ribs usually sharp and narrow. Length, 12 mm.; width, 3.5 mm. Occurrence. — Nayjemoy Formation. Woodstock, Popes Creek. Aquia Formation. 1 mile northeast of Piscataway. Collection . — Maryland Geological Survey. Family FUSIDAE. Genus LATIRUS Montfort. Latirus marylandicus n. sp. Plate XXI, Figs. 12, 12a. Description. — Shell subfusiform, five or more whorled; body whorl with fifteen, blunt, irregular, longitudinal folds, and a number of re- volving ridges, very prominent on the shoulder and gradually dying out toward the beak; entire shell covered by fine, closely-set, raised, revolv- 134 SYSTEMATIC PALEONTOLOGY ing threads, which over-ride both the longitudinal and the revolving folds, the threads showing a tendency to alternate in size; whorls of spire with two, very distinct, revolving folds; major intersecting sets of sculpture giving a reticulate appearance; folds strongly nodular at the intersections; mouth narrow; columella with two, strong, oblique folds; canal long and straight. Length, 26 mm.; width, 11 mm. Occurrence . — Aquia Fokmation. 2 miles below Potomac Creek. Collection . — Maryland Geological Survey. Genus FUSUS (?) Lamarck. The following species are referred to the genus Fusus without any claim that their biological affinities are with that genus as now restricted. They belong to that large group of fossils, of approximately fusoid form, but indeterminate generic relationships. Fusus, (?) SUBTENUIS Heilprin. Plate XXII, Figs. 1, 2. Fusus subtenuis Heilprin, 1880, Proc. Acad. Nat. Sci. Phila., vol. xxxv, p. 371, pi. XX, fig. 4. Description . — Shell fusiform, of about seven subangular volutions; whorls ornamented with somewhat obscure longitudinal folds, about twelve on the body whorl, which are cut by several prominent revolving ridges commencing at the shoulder angulation; shoulder of the whorls more or less smooth, with an obscure median revolving line, and a prominent subsutural one; aperture about the length of the spire, or slightly exceeding it, the canal gently curved, moderately contracted, and somewhat expanding at the extremity; outer lip thin, and showing internally the external ornamentation; base with numerous revolving lines, which alternate in coarseness.^’ Heilprin, 1880. Very characteristic specimens of this species occur at the locality noted below. Length, 35 mm. (restored); width, 18 mm. Occurrence . — Aquia Fokmation. 2 miles below Potomac Creek. Collection . — Maryland Geological Survey. MAEYLAXD GEOLOGICAL SURVEA^ 135 Fuses (?) ixterstriatus Heilprin. Plate XXII, Figs. 4, 4a. Fusus interstriaUcs Heilprin, 1880, Proc. Acad. Nat. Sci. Phila., vol. xxxv, pi. xx, fig. 11. Description . — Shell fusiform, slender, composed of about ten convex volutions, the first three of which are smooth; whorls ornamented with both longitudinal plications and revolving lines, the last of which (about eight in the upper whorls), alternate with finer intermediate striae; the longitudinal plications distinct on the earlier whorls, but becoming much less so on the body whorls, and the one preceding; aperture about the length of the spire; the canal somewhat tortuous; outer lip thin, den- tate within.’’ Heilprin, 1880. The Maryland form differs from that from the Gulf states in that its ribs are alternate, while in the latter they are doubly alternate or with three smaller ones between each pair. The longitudinal plications may be either present or partly absent as on the Gulf form. Length, 16 mm.; width, 6 mm. Occurrence . — Xaxjemoy Foematiox. Woodstock. Aquia Forma- Tiox. 1 mile northeast of Piscataway, Aquia Creek. Collection . — Maryland Geological Survey. Family MURICIDEA. Genus TROPHON Montfort. Trophox subleyis Harris. Plate XXII, Fig. 3. Trophon sublevis Harris, 1899, Bull. Amer. Pal., No. 11, p. 61, pi. viii, figs. 1, 19. Description . — Size and general form as indicated by the figure; whorls seven, embryonic three smooth, spire and body whorl smooth, polished, but with nine sharp-edged costae on each whorl, becoming somewhat pointed on the shoulder; faint undulations indicating indis- tinct, distant spirals between the ribs; outer lip thickened, with five crenulations within, the upper the stronger; no umbilicus.” Harris, 1899. 136 SYSTEMATIC PALEONTOLOGY A single fragment was found which may safely he assumed to repre- sent this species. Lengthy 13 mm. (restored); width, 5 mm. Occurrence . — Aquia Fokmation. 1 mile northeast of Piscataway. Collection . — Maryland Geological Survey. Family BUCCINIDAE. Genus STREPSIDURA Swainson. Steepsiduka subscalaeina Heilprin. Plate XXII, Figs. 5, 6, 7, 8, 8a. Fusus (Strepsidura) subscalarinus Heilprin, 1880, Proc. Acad. Nat. Sci. Pliila., vol. XXXV, p. 372, pi. XX, fig. 8. Fusus {Strepsidura) perlatus Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 4. Fusus {Strepsidura) perlatus Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 67. Description . — Shell somewhat hncciniform, whorls about eight, snb- angular, the first three or four smooth, the remainder ornamented with both longitudinal costae and revolving striae, the latter showing a ten- dency to alternate in size; the costae are arcuate, not in a regularly con- tinnons series, those of the body whorl extending considerably below the middle of the whorl; aperture about the length of spire, the canal somewhat refiected; columella covered with a callous deposit, consider- ably twisted; outer lip dentate within.^^ Heilprin, 1880. Our specimens show a marked tendency to variation both in shape and sculpture, as the figures show, but none of the forms seem to be sufficiently definite to warrant the separation of another species. Occurrence . — Xanjemoy Foemation. Popes Creek, Woodstock. Aquia Foemation. Liverpool Point, Potomac Creek, 2 miles below Potomac Creek, Upper Marlboro. Collections . — Maryland Geological Survey, Johns Hopkins University, Philadelphia Academy of Xatural Sciences. Genus MELONGENA Schumacher. MeLONGENA (?) POTOMACENSIS n. sp. Plate XXII, Fig. 9. Description . — Shell fusiform, showing five angulated whorls (the api- cal whorls and portion of the body whorl wanting); with about twelve MARYLAND GEOLOGICAL SURVEY 137 longitudinal costae, vdiich do not extend above the shoulder; ribs crossed by numerous more or less alternating ridges, of which two on the body whorl, about half-way between the shoulder and the anterior end, are noticeably larger than the others; finer lines of growth cross the ridges forming a somewhat rugose sculpture; above the shoulder smooth with a few small revolving raised lines and still smaller arcu- ated lines of groAvth. The figured specimen is the only one known. It resembles very closely Melongena sul)carinata of the Paris Basin Eocene. There is also a resemblance to Papillina staminea var. Harris^ from Claiborne, Ala- bama. Length, 34 mm.; width, 18 mm. Occuri'ence. — Aquia Formation. Potomac Creek. Collection . — Philadelphia Academy of Aatural Sciences (Ko. 6880 of the Lea Memorial Collection). Genus TUDICLA Bolten. Tudicla marylandica n. sp. Plate XXIII, Figs. 1, la, lb. Description . — Spire flat, concealed except on top by the body whorl which is large, much expanded above, but rapidly contracting below; surface marked by lines of growth, and fine, revolving wrinkles which become strong toward the beak; periphery of body whorl with spines of moderate size; beaks long, narrow, reflexed; columella twisted obtusely. This species differs from P. pyrula Aid. in not having the elevated spire shown in Harris’ figure of a Midwayan specimen,"* and also in not having as elevated a spire, as ovate a mouth, nor being as strongly spinose as the Chickasawan specimens. Length, 70 mm.; width, 50 x 35 mm. Occurrence. — Aquia Formation. 2 miles below Potomac Creek. Collection . — Maryland Geological Survey. 1 Proc. Acad. Nat. Sci. Phila., vol. xlviii, 1890, p. 474, pi. xx, fig. 2. 2 Bull. Amer. Pal., vol. iv, pi. xix, fig. 2. 138 SYSTEMATIC PALEONTOLOGY Tudicla sp. Plate XXIII, Figs. 2, 2a. Fyropsis (?) sp. Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 4. Pyropsis sp. Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 67, pi. xi, figs. 2a, 2b. {?) Pyropsis pyrula Harris, 1899, Bull. Amer. Pal., No. 11, p. 46 (In part). Desci'iption. — Several casts of a large Tudicla have been found at various localities in the Aqnia formation. They differ from T. mary- landica in having a hluntly angulated shoulder. We have not seen the casts from Fort Washington which Professor Harris referred to Py7'opsis pyrula hut they belong probably to this form. Length (of fragment), 40 mm.; width, 55 mm. Occurrence. — Aquia Fohmation. Clifton Beach, Aquia Creek, Crownsville, Fort Washington (Harris). Collections . — Maryland Geological Survey, Cornell University. Tudicla (?) sp. Plate XXIII, Fig. 4; Plate XXIV, Fig. 6. Description. — The cast of a small unknown gastropod is very abund- ant in the indurated ledge at Aquia Creek. It has an obtuse, conic spire, varying in height, and a body whorl much expanded at the top, but diminishing in width below. The beak is moderately long, straight and slender. The spire is wound on or slightly below the shoulder of the whorl. The periphery of the whorl is tuberculate. An imperfect shell having all these characters was also found at Popes Creek. It has a thick shell and is ornamented with distant, raised, revolving lines. Length, 40 (?) mm.; width, 27 mm. Occurrence. — Xanjemoy Fokmation. Popes Creek. Aquia Fokma- TiON. Aquia Creek, Clifton Beach. Collections . — Johns Hopkins Universit}q Maryland Geological Survey. Genus LEVIFUSUS Conrad. Levifusus trabeatus (?) Conrad. Fusus trabeatus Conrad, 1833, Fossil Shells of the Tertiary, No. 3 [1st Edit.], p. 29. Fusus trabeatus Conrad, 1835, Fossil Shells of the Tertiary, No. 3 [2nd Edit.], p. 53, pi. xviii, fig. 1. MAKYLAXD GEOLOGICAL SUKTET 139 Fusiis (Levifusus) trabeatus Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 4. (In part.) Fusus {Levifusus) trabeatus Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 67. (In part.) Description . — “ Shell subfusiform, ventricose, with revolving elevated striae at the base, and more obscure ones on the spire : body whorl with two distinct rows of tubercles, humeral one continued on the spire.’’ Conrad, 1829. Several fragments of molds of the exterior, as well as less clearly de- fined casts of the interior, have been found. They cannot be identified with L. trabeatus with certainty. The casts from Aqnia Creek which were formerly identified with this species are evidently of an indetermi- nate Tudicla. Occurrence . — Naxjemoa^ Foematiox. Popes Creek. Collection. — Maryland Geological Survey. Levifusus tkabeatus (?) var. Plate XXIII, Fig. 3. Description . — A single, imperfect specimen was found at Woodstock which cannot be distinguished in its present condition from a Fulgur. It would be unwise, however, to assume the presence of that genus in the Eocene without better evidence than a single cast. The specimen is too imperfect for description but a figure is given and the form tenta- tively referred to a variety of the preceding species. The substance of the shell is very thin and apparently smooth. The shoulder is carinate or tuberculate. The suture does not seem to be channeled. Length, 73 mm.; width, 25-40 mm. (flattened). Occurrence. — Xaxjemoy Foematiox. Woodstock. Collection. — Maryland Geological Survey. Genus METULA Adams. Metula maeylaxdica n. sp. Plate XXIII, Fig. 5. Description . — Shell small, elongate, six-whorled; sculpture of longitu- dinal folds and elevated revolving ribs; body whorl with thirteen longi- 140 SYSTEMATIC PALEONTOLOGY tiidinal folds, and about fifteen, raised, obtusely rounded, revolving ribs becoming alternate toward the base; other whorls with six ribs; lines of growth fine and sharp; onter lip with ten, irregnlarly spaced teeth; canal short, slightly curved. Length, 11 mm.; width, 5 mm. Occurrence. — Aquia Fokmation. 2 miles below Potomac Creek, Po- tomac Creek, 1 mile southeast of Mason Springs. Collection . — Maryland Geological Survey. Genus CHRYSODOMUS Swainson, Chrysodomus engonatus (Heilprin). Plate XXIII, Pig. 6. Fusus {Hemifusus?) engonatus Heilprin, 1880, Proc. Acad. Nat. Sci. Phila., vol. XXXV, p. 372, pi. XX, fig. 8. Descri'ption . — Shell turreted, of about ten volutions, the first three whorls smooth and convex, the remainder strongly carinated, and trans- versed by numerous fine revolving lines, which on the median portion of the body whorl alternate with intermediate finer striae; body whorl impressed immediately below the carination (shoulder angulation); lines of growth sinous, and approximating the characteristic lines of the Pleurotomidae; aperture considerably exceeding the spire in length; columella slightly arcuate, and presenting a rudimentary fold at about its central portion.’^ Heilprin, 1880. Length, 33 mm.; width, 16 mm. Occurrence . — Aquia Formation. 2 miles below Potomac Creek, Po- tomac Creek. Collections. — Maryland Geological Survey, Philadelphia Academy of Natural Sciences. Genus PSEUDOLIVA Swainson. Pseud OLIVA sp. Plate XXIII, Fig. 7. Description. — Only internal casts of this form have been found. They are not unlike in size and shape to P. venusta (Conrad), but it is not safe to attempt a specific determination. MAEYLAXD GEOLOGICAL SUEYEA" 141 Length, 30 mm.; Yndth, 17 mm. Occurrence . — Aquia Foemation. Upper Marlboro, Hardesty. Collection . — Maryland Geological Survey. Superfamily TAENIOGLOSSA. Family TRITONIDAE. Genus TRITONIUM Link. Teitonium showalteei (Conrad). Plate XXIY, Figs. 1, la. Simpulu7n showalteri Conrad, 1860, Jour. Acad. Nat. Sci. Phila., vol. iv, p. 292, pi. xlvii, fig. 11. Description. — Fusiform; whirls eight, angular, periphery of angle acute, situated below the middle of the vdiirl; whirls of spire costate longitudinally, but not very distinctly; revolving lines closely arranged, fine, with a few distant prominent lines; three first whirls of -the spire smooth, the next two tnberculated; angle tnbercnlated; a promi- nent, acute line on the body whirl runs from the upper extremity of the aperture, and a similar finer line between it and the angle above; colum- ella rugose, with a prominent fold near its upper end; labium dentate within.” Conrad, 1860. Length, 26 mm.; width, 13 mm. Occurrence . — Aquia Foemation. Month of Paspotansa Creek, 2 miles below Potomac Creek. Collection . — Maryland Geological Survey. Family DOLIIDAE. Genus PYRULA Lamarck. Pyeula penita vae. Conrad. Plate XXIV, Fig. 2. Pyrula penita Conrad, 1833, Fossil Shells of the Tertiary, No. 3 [1st Edit.], p. 32. Pyrula cancellata Lea, 1833, Contrib. to Geol., p. 154, pi. v, fig. 160. Pyrula elegantianma Lea, 1833, Contrib. to Geol., p. 155, pi. v, fig. 161. Pyrula tricarinata Conrad, 1835, Fossil Shells of the Tertiary, No. 3 [2nd Edit.], p. 38, pi. XV, fig. 6. Description . — “ Shell snbfnsiform, reticulated, with three carinations on the body whorl: striae alternating in size: five volutions; spire ele- vated and pointed. Lip thickened toward the margin. 142 SYSTEMATIC PALEONTOLOGY ‘^Variety, C. Destitute of carinations, and probably the young shell. Length about an inch.” Conrad, 1833. Several specimens have been found which are very close to this species. They are nearer the Variety C. suggested by Conrad and named P. ele- gantissima by Lea. Length, 27 mm.; width, 12 mm. Occurrence. — Nanjemoy Foemation. Popes Creek. Collection . — Maryland Geological Survey. Pykula (?) sp. Plate XXIV, Fig. 5. Description. — Shell thin; body whorl large, convex; sculpture of nu- merous, closely set, revolving, impressed lines, very strongly and con- stantly punctate. Only one specimen has been found and it is very imperfect. The spire is entirely gone. Length (of fragment), 14 mm.; width, 11 mm. Occurrence . — Xanjemoy Foemation. Popes Creek. Collection . — Johns Hopkins University. Genus FULGUROFICUS Sacco. Fulgueoficus aegutus Clark. Plate XXIV, Figs. 3, 3a. Fulgur argutus Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 4. Fulgurojicus argutus Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 68, pi. xii, figs, la, 16. Fulgurojicus triserialis Harris, 1899, Bull. Amer, Pal., No. 11, p. 67, pi. viii, fig. 17. (In part.) Description. — Shell moderately short, with four or five whorls; first two whorls apparently smooth; third whorl with faintly impressed spiral lines and minute transverse riblets; later whorls with spinous tubercles at the shoulder; body whorl also with two lower rows of tubercles ar- ranged along strongly elevated spiral ridges and transversely placed vertically above one another; ten to fourteen tubercles in each row; nu- merous fine spiral threads also pass over the spinous ridges and inter- MAEYLAND GEOLOGICAL SUEVEA" 143 spaces; lines of growth somewhat irregular; canal rather long, narrow/^ Clark, 1896. This species differs from F. triserialis Whitfield in having the three rows of tubercles of nearly equal strength, and spaced at nearly equal distances, in having more elevated spire, and in having that portion of the body whorl, of which the middle row of tubercles is in the center, uniformly convex throughout, instead of sharply angulated at the shoulder and nearly fiat below. Length, 27 mm.; width, 18 mm. Occurrence. — Nanjemoy Foemation. Woodstock. Aquia Foema- Tiox. Potomac Creek, 2 miles below Potomac Creek, Pomonkey Neck, Upper Marlboro. Collections . — Maryland Geological Survey, U. S. National Museum, Philadelphia Academy of Natural Sciences, Johns Hopkins University. Genus FUSOFICULA Sacco. Fusoficula juvexis (Whitfield). Plate XXIV, Figs. 4, 4a. Pyrula juvenis Whitfield, 1865, Amer. Jour. Conch., vol. i, p. 259. Fusoficula juvenis Harris, 1899, Bull. Amer. Pal., No. 11, p. 66, pi. viii, figs. 15, 16. Description . — Shell small and fragile; spire elevated; columella slender, slightly bent; aperture large, elongate, ovate or sub-elliptical; volutions three; marked on the periphery by three distinct carinae or sub- angular revolving ridges, the upper one marked with closely arranged, longitudinally elongated nodes, the others simple; entire surface marked by very fine revolving lines, which are somewhat fasciculate below the lower Carina, there being three finer ones between each large one.” Whitfield, 1865. A single specimen of typical form and excellent state of preservation was found. Length, 23 mm.; width, 11 mm. Occurrence. — Aquia Foematiox. 2 miles below Potomac Creek. Collection . — Maryland Geological Survey. 144 SYSTEMATIC PALEONTOLOGY Family CASSIDIDAE. Genus MO RIO Montfort. Morio brevidentata (Aldrich). Plate XXIV, Fig. 7. Cassidaria hrevidentata Aldrich, 1885, Jour. Cin. Soc. Nat. Hist., p. 152, pi. iii, fig. 20. Description. — Shell, ohlong-oval, whorls seven; suture, channeled; surface covered with fine revolving striae; coarser, distant lines upon the body whorl, giving the shell the carinated aspect of the genus; lines of growth fine, a few coarser ones showing on the line of the tubercles; apex, smooth; whorls of the spire carinate and slightly tubercled; a row of upright longitudinal nodes on the shoulder of the body whorl, none below; a single, strong varix on the body whorl; aperture, ovate; inner lip spreading over the whorl, with three plications on the upper part, smooth in the central part and plicate below; outer lip reflected, plicate on the inner edge above and below, smooth in the center; canal, narrow, strongly twisted.’^ Aldrich, 1885. Length, 30 mm.; width, 20 mm. Occurrence . — Aquia Formation. 1 mile southeast of Mason Springs, 2 miles below Potomac Creek. Collection . — Maryland Geological Survey. Family CYPRAEIDAE. Genus CYPRAEA Linnl Cypraea smithii Aldrich. Plate XXIV, Fig. 8. Cypraea smithii Aldrich, 1886, Geol. Survey, Ala., Bull. 1, p. 33, pi. v, fig. 3. Description . — Shell oblong-ovate, rather flat, surface smooth; labium crenulate within, smooth on the base and flattened, reflected somewhat and raised above base of shell; aperture slightly crenulate within, ex- panded helow.’^ Aldrich, 1886. Fragments of a Cypraea which in their somewhat imperfect condition show no characters which would prevent their being referred to C. smithii are fairly abundant in the Potapaco member, hut seem to he much restricted in vertical range. MAEYLAXD GEOLOGICAL SURVEY 145 Length, 18 mm.; width, 15 by 8 mm. (crushed). Occurrence. — Xaxjemoy" Forwatiox. West of Port Tobacco, mile below Chapel Point, Head of Hanjemoy Creek. Collection . — Maryland Geological Survey. Family STROMBIDAE. Genus CALYPTRAPHORUS Conrad. Calyptraphorus jacksoxi Clark. Plate XXV, Figs. 1, la, 2. CalypLrophorm jacksoni Clark, 1895, .Johns Hopkins Univ. Circ., vol. xv, p. 4. Calyptrophorus jacksoni Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 68, pi. xii, figs. 2a, 26. Description . — Shell large, solid, many whorled; spire prolonged, acu- minate; surface of adult covered with thick, calcareous deposit, entirely enveloping the whorls; inner lip thickened with extensive callosity.” Clark, 1896. This very remarkable form is quite distinct from any other species, but some of the Gulf types ajjproach it in size and amount of callosity. Some of the largest specimens of C. trinodiferus Conrad show certain points of similarity, but the Maryland species cannot be confounded with it. In the absence of young shells, the character of the surface decoration is unknown. A large number of specimens have been found in the South Eiver area. Length (restored), 102 mm.; width, 44 mm. Occurrence. — Aquia Forwatiox. South Eiver, Upper Marlboro. Collections . — Maryland Geological Survey, Johns Hopkins University, Museum of Comparative Zoology. Calyptraphorus trixodiferus Conrad. Plate XXV, Fig. 3. Calyptraphorus trinodif eru.'i Conrad, 1857, Proc. Acad. Nat. Sci. Phila., vol. ix, p. 166. Calyptraphorus trinodiferus Conrad, I860, Jour. Acad. Nat. Sci. Pbila., 2nd ser., vol. iv, pi. xlvii, fig. 29. Description . — Subfusiform, with three distinct nodes on the upper part of the body volution; spire subtriangular, having curved longitu- 10 146 SYSTEMATIC PALEONTOLOGY dinal ribs visible beneath the tnnic; rostrum of the spire elongated and curved; labrnm with a prominent angle above/^ Conrad, 1857. Length, 45 mm.; width, 18 mm. Occurrence . — ^^anjemoy Foemation. Potomac Creek (Zone 11). Aquia Foemation. 2 miles below Potomac Creek. Collection . — Maryland Geological Survey. CaLYPTEAPHOEUS TEINODIFEEUS (?) VAE. Plate XXV, Figs. 4, 4a. Description . — This form has the prolonged spire and longitudinal rib- bing of C. trinodiferus, differing from it only in lacking the nodes. It might perhaps be referred to a variety of C. velatus, but the characters which separate it from C. velatus seem less likely to be accidental than those separating it from C. trinodiferus. In the Philadelphia Academy of Xatnral Sciences are a few specimens of C. velatus which have the prolonged spire of this form, but none have the ribbing on the spire. Length, 46 mm.; width, 15 mm. Occurrence . — Xanjemoy Foemation. Popes Creek. Aquia Foema- tion. 1 mile southeast of Mason Springs. Collection . — Maryland Geological Survey. Family APORRHAIDAE. Genus APORRHAIS da Costa. Apoeehais potomacensis n. sp. Plate XXV, Figs. 5, 6. Description . — Shell fusiform; spire elevated, pointed; body whorl large; outer lip much expanded; digitations, two, slender and long; pos- terior digitation about twice as long as the anterior; callus on the inner lip thick; whorls strongly convex and somewhat angnlated below the middle; body whorl with two obtuse revolving ribs, which extend down the middle of the digitations, and disappear in the opposite direction beneath the callus on the labium; about twenty longitudinal ribs on each whorl, with a deep curve below the suture, overridden by fine, raised, close-set, revolving lines. MAEYLAXD GEOLOGICAL SUKVEY 147 Length, 25 mm.; width (of body whorl), 10 mm.; length of posterior digitation, 22 mm. Occurrence . — Aquia Fokmatiox. 1 mile northeast of Piscataway, Paspotansa Creek, 2 fliiles below Potomac Creek. Collection . — Maryland Geological Survey. Family TURRITELLIDAE. Genus TURRITELLA Lamarck. Tueeitella moetoxi Conrad. Plate XXVI, Figs. 1-5. Turritella mortoni Conrad, 1830, Jour. Acad. Nat. Sci. Pliila., vol. vi, p. 221, pi. x, flg. 2. Turritella mortoni Conrad, 1832, Fossil Shells of the Tertiary, No. 3 [2nd Edit.], p. 40, pi. XV, flg. 11. Turritella mortoni Morton, 1834, Synopsis Organ. Rem. Cretaceous Group, App., p. 4. Turritella mortoni H. C. Lea, 1848, Proc. Acad. Nat. Sci. Phila., vol. iv, p. 107. Turritella mortoni Conrad, 1865, Amer. Jour. Conch., voL i, p. 32. Turritella mortoni de Gregorio, 1^0, Ann. Geol. et Pal., p. 122, pi. xi, flg. 7. Turritella mortoni var. postmortoni Harris, 1894, Amer. Jour. Sci., ser. iii, vol. xlvii, p. 303, flirs. 1, 2, 3. Turritella mortoni Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 4. Turritella mortoni Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 69, pi. xiii, flgs. la-le. Turritella mortoni Harris, 1899, Bull. Amer. Pal., No. 11, p. 74, pi. x, flgs. 3, 4. Description . — Shell turreted, conical, thick, with revolving distant, and finer intervening striae; whorls with an elevated acute carina near the base of each; volutions about eleven; the striae are largest on the elevations of the whorls, which are slightly concave above, and abruptly terminate at the sutures; the lines of growth on the last whorl are strong and much undulated.^' Conrad, 1830. This important species was one of the first to be recognized in the Maryland Eocene, and has been generally regarded as one of the most characteristic, as it is one of the most common forms. At times it makes up whole beds, as shown in the Paspotansa member of the Aquia formation at Aquia Creek, Potomac Creek, and other neighboring lo- calities. Turritella mortoni shows very great variations in the form and deco 148 SYSTEMATIC PALEONTOLOGY ration of the whorls, and if it were not for the great number of inter- mediate types one might readily, establish several independent species. Some specimens have nearly equally rounded whorls with evenly spaced spiral lines, while others are prominently*carinated toward the base of the whorl and the spiral threads are irregularly spaced, varying in prominence and number. A variety named postmortoni by Harris is characterized by its rather smaller size, plainer surface, and extremely sharp basal carina. Figure 5 represents this form. Length, 130 mm.; width, 33 mm. Occurrence. — Aquia Formation. Fort Washington, 1 mile northeast of Piscataway, Northwest of Piscataway (W. of Tinkers Cr.), Brooks Es- tate near Seat Pleasant, Glymont, Liverpool Point, Clifton Beach, 1 mile southeast of Mason Springs, Aquia Creek, Potomac Creek, Upper Marlboro, Sheckels Farm near South Eiver, 1 mile west of Hardesty, Eolph’s Landing. Collections. — Maryland Geological Survey, Johns Hopkins University, U. S. National Museum, Philadelphia Academy of Natural Sciences. Turritella humerosa Conrad. Plate XXVII, Figs. 1, la. Turritella humerosa Conrad, 1835, Trans. Geol. Soc., Penn., p. 340, pi. xiii, fig. 3. Turritella humerosa H. C. Lea, 1848, Proc. Acad. Nat. Sci., Phila., vol. iv, p. 107. Turritella humerosa Conrad, 1865, Amer. Jour. Conch., vol. i, p. 32. Turritella humerosa Conrad, 1866, Smith. Misc. Coll. (200), p. 11. Txirritella Immerosa Harris, 1894, Amer. Jour. Sci., ser. iii, vol. xlvii, p. 303. Turritella humerosa Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 4. Turritella humerosa Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 70, pi. xiv, fig. 1. Turritella Immerosa Harris, 1899, Bull. Amer. Pal., No. 11, p. 75, figs. 5, 6, 7. Description . — Shell turreted^ subulate; whorls with fine regular re- volving striae; an obtuse slight elevation on the summit, a shallow groove at the base of each.^’ Conrad, 1835. Turritella humerosa, although not an uncommon species, is far less frequent than T. mortoni. It is very readily separated from the latter by its flat whorls and prominent siihsutural carina, which makes the whorls of nearly equal diameter above and below. MARYLAND GEOLOGICAL SURVEY 149 This species apparently never reaches the dimensions of T. mortoni, hnt is commonly associated with it. Like T. mortoni, it is largely con- fined to the Paspotansa member of the Aqnia Formation. Length, 140 mm.; width, 25 mm. Occurrence. — Aquia Formation. Fort Washington, Clifton Beach, Aqnia Creek, 1 mile southeast of Mason Springs, Glymont, Month of Paspotansa Creek, 1 mile northeast of Piscataway, Near Annapolis, Be- tween Bnena Vista and Collington, Tinkers Creek, Liverpool Point, Tapper Marlboro, Sheckels Farm near South Eiver, Brooks Estate near Seat Pleasant. Collections. — Maryland Geological Survey, Johns Hopkins University, L^. S. National Mnsenm, Philadelphia Academy of Natural Sciences. Turritella potomacensis n. sp. Plate XXVII, Figs. 2, 3. Description . — Shell slender, elongate; whorls many; each whorl cari- nated at the base, diminishing sharply in diameter toward the apex, and concave in the middle; sculpture consisting of one or two strong, ele- vated carinae at the base of the whorl, and about five moderately strong ones, irregularly spaced above them, and between these secondary alter- nating threads and fine, raised, revolving lines; some of the carinae, especially those toward the middle of the whorl, are headed. Length, 45 mm.; width, 10 mm. Occurrence . — Nanjemoy Formation. Popes Creek, Woodstock. Collection. — Maryland Geological Survey. Genus MESALIA Gray. Mesalia obruta (Conrad). Plate XXVII, Fig. 4. Turritella obruta Conrad, 1833, Fossil Shells of the Tertiary, No. 4, p. 4.5 ; No. 3 [2nd Edit.], 1835, p. 40. pi. xv, ti^^. 12. Turritella venusta Conrad, 1835, Trans. Geol. Soc., Penn., vol. i, p. 336. Description. — Snhnlate, with ahont eleven slightly convex volutions, with about seven sharp elevated striae on each, and intermediate fine crowded lines; space about the suture indented.’’ Conrad, 1833. 150 SYSTEMATIC PALEONTOLOGY This form is very abundant in the IsTanjemoy formation, and occurs near the top of the A quia formation at Upper Alarlboro, in the indurated ledge and just above it, and also in the same bed near South Eiver bridge. Length, 30 mm.; width, 10 mm. Occurrence. — Nanjemoa" Formation. Popes Creek, Woodstock. Aquia Formation. Upper Marlboro, Sheckels Farm near South Eiver. Collectio7i . — Maryland Geological Survey. Family VERMETIDAE. Genus VERMETUS Adams. Vermetus sp. Plate XXVII, Figs. 5, 5a, 6, 7. Vermetus sp. Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 4. Vermetus sp. Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 71, pi. xiv, figs. 2a, 2b. Description . — Fragmentary masses of this form are found at various points in the Potomac Eiver region, but no specimen sufficiently well preserved for specific determination has been obtained. The fragments, however, probably represent a new species. The form is characterized by longitudinal furrows, giving it a somewhat angulated appearance, and by transverse, scaly lines interrupted by the furrows. The average diameter of the tubes is about 2 mm. Occurrence . — Aquia Formation. Piscataway Creek, Potomac Creek, Eolph’s Landing, Upper Marlboro. Collections. — U. S. Xational Museum, Johns Hopkins University, Maryland Geological Survey. Family NATICIDAE. Genus NATICA Lamarck, Natica cliftonensis Clark. Plate XXVIII, Fig. 1. Natica cliftonensis Clark, 1895, Jolms Hopkius Univ. Circ., vol. xv, p. 4. Natica cliftonensis Clark, 1890, Bull. 141, U. S. Geol. Survey, p. 69, pi. xii, fig. 4. Description . — “ Shell small, with four or five whorls; spire low; body whorl much inflated; suture well marked; surface smooth, except for lines of growth; aperture large, with thick callus.” Clark, 1896. MARYLAND GEOLOGICAL SURVEY 151 In addition to the type we have only a crnshed Natica from Wood- stock that may represent this species. Length, 10 mm.; wddth 12 mm. Occurrence. — Xaxjemoy Formation. Woodstock. (?) Aquia For- mation. Clifton Beach. Collections. — Maryland Geological Survey, Johns Hopkins University. Genus LUNATIA Gray. Lunatia marylandica Conrad. Plate XXVIII, Figs. 2, 2a, 3. Lunatia marylandica Conrad, 186.'5, Amer. Jour. Conch., vol. i. pp. 26, 211, pi. xxi, fig. 11. Lunatia marylandica Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 4. Lunatia marylandica Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 69, pi. xii, figs 3a— 3c. cf. Natica eminula var. Harris, 1899, Bull. Amer. Pal., No. 11, p. 88, pi. xi, fig. 22. Description . — Snhorbicnlar or snbovate, volutions 5; spire short, whorls convex, subcontracted below the suture; labium with a callus on the upper part, reflected over the umbilical margin; umbilicus moderate in outline, profound, showing most of the volutions.’^ Conrad, 1865. The stratigraphic and geographic range of this species is very great. It is larger, however, and more abundant in the lower beds of the Aquia formation. The afflnities of the species are with L. eminula (Conrad) of Alabama, especially with L. eminula var. Harris, of the Alabama Chickasawan, which is an intermediate member of a series of which the Claibornian L. eminula and L. marylandica are end members. The separation of these species is very difficult, and possibly all the forms ought to be referred to L. eminula which is the older name. The Maryland forms show almost, if not quite, the complete range of varia- tion of the series. Length, 32 mm.; width, 30 mm. Occurrence. — Xanjemoy Formation. East and west of Port Tobacco, Woodstock. Aquia Formation. 1 mile northeast of Piscataway, Po- tomac Creek, 2 miles below Potomac Creek, Upper Marlboro, Liverpool Point, Mouth of Paspotansa Creek, Aquia Creek, 1 mile southeast of Mason Springs, Glymont, Hardesty, Fort AVashington. 152 SYSTEMATIC PALEONTOLOGY" Collections . — Maryland Geological Survey, Johns Hopkins University, U. S. National Museum, Philadelphia Academy of Natural Sciences. Family CAPULIDAE. Genus CALYPTRAEA Lamarck, Cala"ptkaea aperta (Solander). Plate XXVIII, Pigs. 4, 5. Trochus apertus Solander, 1766, Foss. Haut., p. 9, figs. 1, 2. Calyptraea trochiformis Lamarck, 1804, Ann. Mns. d’Hist. Nat., vol. i, p. 1.5, fig. 3. Calyptraea trochiformis Clark, 1895, Jolms Hopkins Univ. Circ., vol. xv, p. 4. Calyptraea trochiformis Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 70. Calyptraea aperta Harris, 1899, Bull. Aiuer. Pal., No. 11, p. 84, pi. xi, figs. 18-16. Description . — Shell orbicular, thin, obtusely conical; volutions three or four; apex suhcentral; later whorls spinose; whole surface (except protoconch) roughened with irregular, wavy lines of growth, or a vermi- cular shagreening; septum slightly concave; pillar reflected, giving the appearance of an umbilicus. This species is represented, usually in a poorly preserved state, in nearly all the beds and localities of the Maryland Eocene. The largest specimens are in the Aquia formation. Length, 15 mm.; width, 28 mm. Occurrence . — Nan.jemoa" Formation. Popes Creek, Woodstock, East and west of Port Tobacco, \ mile below Chapel Point. Aquia Forma- tion. Fort IVashington, Glymont, Clifton Beach, Liverpool Point, Up- per Marlboro, Aquia Creek, Potomac Creek, 2 miles below Potomac Creek, 1 mile southeast of Mason Springs. Collection . — Maryland Geological Survey. Family LITTORINIDAE. Genus LITIOPA Rang. Litiopa marylandica n. sp. Plate XXVIII, Figs. 6, 6a. Description . — Shell thin, with six whorls; the first two whorls smooth^ the third with fine, closely-set, revolving striations from suture to su- MARYLAND GEOLOGICAL SURVEY 153 tiire, the fourth with striations on the upper half, the lower half being smooth, the fifth and sixth (body) whorls smooth, except for very faint, revolving lines, which are less distinct than the lines of growth, and about eight, sharp, revolving lines around the umbilicus; callosity on the labium thin; umbilicus moderate; mouth large; columella concave above. Length, 8 mm.; width, 4 mm. Occurrence. — Aquia Formation. 2 miles below Potomac Creek. Collection . — ]\Iaryland Geological Survey. Superfamily PTENOGLOSSA. Family SOLARllDAE. Genus SOLARIUM Lamarck. Solarium sp. Plate XXVIII, Figs. 7, 7a. Solarium sp. Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Solarium sp. Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 71, pi. xiv, tigs. 4«, 46. Xo new material belonging to this genus has been obtained except an indeterminate fragment from near Mason Springs. Xeither this, nor the cast from Aquia Creek, give any clew to the specific characters. Length, 6 mm.; width, 16 mm. Occurrence. — Aquia Formation. Aquia Creek, 1 mile southeast of Mason Springs. Collection . — Johns Hopkins University, Maryland Geological Survey. Family SCALARllDAE. Genus SCALA Klein. ScALA viRGiNiANA Clark. Plate XXVIII, Figs. 8, 8a, 9, 9a. Scala virginiana Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 4. Scala virginiana Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 71, pi. xiv, ligs. 3a, 36. Description . — Shell probably seven- or eight-whorled; surface cov- ered with a uniform, fine, spiral striation; varices fifteen to the whorl. 154 SYSTEMATIC PALEONTOLOGY inflected forward and prominent; some of the varices are more promi- nent than others, and in a few instances are partially divided by a central groove; aperture nearly round/^ Clark, 1896. Some specimens show a large umbilicus, in others it is absent. Length, 22 mm.; width, 14 mm. Occurrence. — Aquia Fokmation. Aquia Creek, Potomac Creek. Collection . — U. S. National Museum, Philadelphia Academy of Natural Sciences. SCALA POTOMACENSIS n. Sp. Plate XXVIII, Fig. 10. Description . — Shell elongate, moderately slender, eight-whorled; mouth round; base with numerous, closely-set, revolving lines and folds radiating to the varices; whorls closely-set; moderately and uniformly convex; varices low, obtuse, twenty-five on the body whorl, and about as many on the whorls of the spire, stronger than ordinary, and occurring at irregular intervals; raised revolving threads, about 30 in number, alternating and doubly alternating in strength, run between without crossing the varices. Length, 20 mm.; width, 8 mm. Occurrence. — Aquia Formation. 2 miles below Potomac Creek. Collection . — Maryland Geological Survey. ScALA SESSiLis Conrad. Plate XXVIII, Fig. 11. Scala sessilis Conrad, 1833, Fossil Shells of the Tertiary, No. 4, p. 45. Description. — Subulate, with rather thick longitudinal costae, and minute crowded spiral lines; whorls nine, sessile or contiguous; base of the body whorl carinated.’^ Conrad, 1833. Occurrence. — Aquia Formation. 2 miles below Potomac Creek. Collection . — Maryland Geological Survey. Scala carinata Lea. Plate XXVIII, Fig. 12. Scala carinata Lea, 1833, Contrib. to Geol., p. 116, pi. iv, fig, 103. Description . — “ Shell conical, closely ribbed, carinate on the inferior part of the last whorl; substance of the shell thick; spire elevated. MAKYLAND GEOLOGICAL SUKVEY 155 pointed; ribs about twelve, lamelliform; whorls six, rounded; mouth roimd/^ Lea, 1833. Occurrence. — Aquia Fokmation. 2 miles below Potomac Creek, Up- per Marlboro. Collection. — Maryland Geological Survey. Superfamily GYMNOGLOSSA. Family PYRAMIDELLIDAE. Genus TURBONILLA Risso. Subgenus PYRGISCUS Philippi. Tukbonilla potomacensis n. sp. Plate XXIX, Fig. 1. Description. — Shell stout; whorls eight, moderately convex; about twenty-five slightly curved, longitudinal ribs on the body whorl, crossed by eight, impressed, revolving lines, which are deepest between the ribs; base of shell with impressed, revolving lines, and faint, radiating ribs; mouth ovate. Length, 10 mm.; width, 4 mm. Occurrence. — Aquia Formation. Potomac Creek, 2 miles below Po- tomac Creek. Collection . — Maryland Geological Survey. Genus TUBA Lea. Tuba marylandica n. sp. Plate XXIX, Fig. 2. Description. — Shell elongate; whorls seven, strongly convex, covered with eight raised revolving threads, with narrower interspaces; threads strongly beaded by intersections with raised longitudinal lines. Length, 12 mm.; width, 5 mm. Occurrence. — Nanjemoy Formation. Popes Creek. Aquia Forma- tion. Mouth of Paspotansa Creek, 1 mile southeast of Mason Springs. Collection. — Maryland Geological Survey. 15G SYSTEMATIC PALEONTOLOGY Genus ODOSTOMIA Fleming. Odostomia tkapaquaka (Harris). Plate XXIX, Fig. 3. Syryiola irapaquara Harris, 1895, Proc. Acad. Nat. Sci. Phila., vol. xlvii, p. 77, pi. viii, tig. 10. Description . — Size and general form as indicated by the figure; whorls 7; 1 small, sinistral; 2-7 polished, slightly tnmid, with a well- marked suture; aperture moderate, striate within; one strong plait on the columella.’’ Harris, 1895. This species has some resemblance to the figure of Acteon melanellus Lea, but it tapers more gradually, has shorter whorls, stronger lines of growth and no revolving lines (or almost none), while they are strong in A. melanellus. Our specimens are very different from the Chickasawan form — 0. in- significa Aldrich, which Harris regards as a synonym of 0. trapaquara. Length, 7 mm.; width, 2.5 mm. Occurrence. — Aquia Fokmation. Potomac Creek, 2 miles below Po- tomac Creek, Upper Marlboro. Collection . — Maryland Geological Survey. Family EULIMIDAE. Genus NISO Risso. XlSO UMBILICATA (Lea). Plate XXIX, Fig. 4. Pasithea umbilicata Lea, 1833, Contrib. to Geol., p. 103, pi. iv, tig. 85. Description . — Shell elevated above, rounded below, subcarinate, pol- ished; substance of the shell thin; apex acute; suture linear; umbilicus large; Avhorls nine, flattened; mouth subovate, acutely angular above, one-fifth the length of the shell; columella incurved at base; margin en- tire. ... Its umbilicus is wide, with a large spiral groove. On some of the wliorls the line of growth may be indistinctly seen.” Lea, 1833. Length, 24 mm.; width, 5 mm. Occurrence. — Aquia Formation. Potomac Creek. Collection . — Maryland Geological Survey. MARYLAND GEOLOGICAL SURVEY 157 Order ASPIDOBRANCHIATA. Suborder RHIPIDOGLOSSA. Family TROCHIDAE. Genus GIBBULA Risso. Gibbula glandula (Conrad). Plate XXIX, Fig. 5. 2fonodonta glandula Conrad, 1830, Jour. Acad. Nat. Sci. Phila., vol. vi, pp. 214, 220, pi. ix, fig. 15. Monodonta glandula H. C. Lea, 1848, Proc. Acad. Nat. Sci. Phila., vol. iv, p. 102. 2Ionodonta glandula Conrad, 1866, Smith. Misc. Coll. (200), p. 11. Gihhula glandula Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Gibbula glandula Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 72, pi. xiv, fig. 5. Description . — “ Shell conical, with about four convex volutions; re- volving striae fine, crowded and wrinkled; suture deeply impressed; right lip toothed within at the base; margin entire. The teeth or tubercles extend to the base of the columella of this shell.’^ Conrad, 1830. Length, 8 mm.; width, 7 mm. Occurrence. — Aquia Formation. Piscataway (Conrad), Potomac Creek, Upper Marlboro. Collections . — Johns Hopkins University, Maryland Geological Survey, Philadelphia Academy of Xatural Sciences. Genus CALLIOSTOMA Swainson. Calliostoma sp. Description. — Two specimens of Calliostoma, both too imperfect either to figure or to describe, were found in the Aquia formation. The one from below Potomac Creek is part of the base of the body whorl. It shows a strong basal carina, and revolving threads of various size, all slightly granulate. The fragment from Upper Marlboro does not show the surface decoration, hut has a deep groove in the middle of the whorl. Occurrence . — Aquia Formation. Upper Marlboro, 2 miles below Po- tomac Creek. Collection . — Maryland Geological Survey. 158 SYSTEMATIC PALEONTOLOGY Family FISSURELLIDAE. Genus FISSURIDEA Swainson. Fissukidea maklboroensis n. sp. Plate XXIX, Figs. 6, 6a. Description . — Shell ovate, depressed; apex anteriorly situated, acute; foramen keyhole-shaped, anterior to the apex, plane sloping forward; internal callus shaped like the end of a gun-stock, deeply dinted behind; surface sculptured by fine, impressed, radiating lines, with broad and fiat interspaces toward the periphery, raised and rounded toward the apex; interspaces doubly alternating in width or height, every fourth being much wider, while of each group of intervening narrower ones that in the middle is slightly wider than the rest; alternation becomes simple on the posterior slope, with double alternation strongest on the anterior slope. Length, 17.5 mm.; width, 12 mm.; height, 6 mm. Occurrence . — Aquia Formation. Upper Marlboro. Collection . — Maryland Geological Survey. Class SCAPHOPODA. Order SOLENOCONCHIA. Family DENTALllDAE. Genus DENTALIUM Linnk Dentalium minutistriatum Gabb. Plate XXIX, Fig. 7. Dentalium minutistriatum Gabb, 1860, Jour. Acad. Nat. Sci. Phila., 2nd Ser., vol. iv, p. 386, pi. Ixvii, tig. 46. Description . — ^^Very slightly curved, marked by numerous small lon- gitudinal ribs, all of the same size, no trace of alternation; aperture round.^’ Gabb, 1860. This form differs from D. mississippiensis in having finer, non-alter- nate ribbing, and not attaining to so great a size. MAKYLAXD GEOLOGICAL SURVEY 159 The figured specimen (besides which only fragments have been found) is strongly and regularly compressed in the plane at right angles to that of curvature. So natural does the compression appear that the indi- vidual was referred to the genus Compressidens of Pilshry. But other fragments have been found which have a perfectly round aperture, and faint cracks have been discovered along the lines of greatest curvature of the compressed specimen, and therefore the character must probably be regarded as accidental. Length, 17 mm.; width, 1.75x2.5 mm. (flattened). Occurrence. — Naxjemoy Formation. Popes Creek. Collection . — Maryland Geological Survey. Dentalium mississippiensis Conrad. Plate XXIX, Fig. 8. Dentalium misHssippiensis Conrad, 1848, Jour. Acad. Nat. Sci. Phila., 3ud Ser., vol. i, p. 113, pi. xi, fig. 1. Description . — Curved, attenuated above, longitudinally striated, the lines alternating in size. ... It differs from D. tlialloides in having more numerous and much less prominent lines.” Conrad, 1848. Length, 36 mm.; width, 6 mm. Occurrence. — Xanjemoy Formation. West of Port Tobacco, 1 mile southeast of Piseataway. Aquia Formation. Upper Marlboro. Collection . — Maryland Geological Survey. Family SIPHONODENTALIIDAE. Genus CADULUS Philippi. Cadulus abruptus Meyer and Aldrich. Plate XXIX, Fig. 9. Cadulusi ahruptus Meyer and Aldrich, 1887, Jour. Cin. Soc. Nat. Hist., vol. ix. No. 3, p. 40, pi. ii, fig, 3. Cadulus hellulus Clark, 189.5, Johns Hopkins Univ. Circ., vol. xv, p. 5. Cadulus belhdus Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 73, pi. xiv, fig. 6. Description. — ‘‘ Rather large, somewhat depressed. Inflation very near to the larger aperture and suddenly decreasing.” Meyer and Al- drich, 1886. 160 SYSTEMATIC PALEONTOLOGY Thin, polished, slightly arched; much contracted near the anterior extremity; anterior opening snhcircnlar, posterior simple. This species differs from C. subcoarctatus Gahb in having the con- striction begin much nearer the aperture. There is no longitudinal striation. Length, 8 mm.; width, 1.25 mm. Occurrence . — Nanjemoa" Fokmation. Woodstock, Head of Hanjemoy Creek, East and west of Port Tobacco, H and 2J miles above Popes Creek, 1 mile southeast of Piscataway, Upper Marlboro (deep cut near Chesapeake Beach E. E. station). Well at Chesapeake Beach (90-92 feet). Aquia Formation. Aquia Creek, Liverpool Point, Clifton Beach, 1 mile northeast of Piscataway. Collection . — Maryland Geological Survey, Johns Hopkins University. Class PELECYPODA. Order TELEODESMACEA. Family TEREDINIDAE. Genus TEREDO LinnA Teredo virginiana Clark. Plate XXX, Figs. 1, la, 2, 2a, 3. Teredo virginiana Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Teredo virginiana Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 72, pi. xv, tigs. 5a-5c. Teredo virginiana Dali, 1898, Trans. Wagner Free Inst. Sci., vol. iii, part iv, p. 813. Description . — “ Shell unknown; tube thick, cylindrical, irregularly curved, rapidly tapering; surface smooth, or with fine lines of growth; prominent transverse segment near posterior extremity of the tube in some of the forms.’’ Clark, 1896. This type compared with the forms described from the Alabama Ter- tiary shows various points of dissimilarity, and even in the absence of the valves seems, from its common occurrence, worthy of a name. The tubes often occur in large masses in pieces of lignite. Diameter of tube (maximum), 5 mm. Occurrence . — Xanjemoi: Formation, J mile below Chapel Point. Woodstock, Hills Bridge, West of Port Tobacco, Upper Marlboro (deep MARYLAND GEOLOGICAL SURVEY 161 cut near Chesapeake Beach E. E. station). Aquia Formation. Upper Marlboro, 2 miles below Potomac Creek, 1 mile southeast of Mason Springs, Clifton Beach, 1 mile northeast of Piscataway. Collections . — Johns Hopkins University, Maryland Geological Survey, Philadelphia Academy of Natural Sciences. Family PHOLADIDAE. Genus PHENACOMYA Dali. Phenacomya petrosa (Conrad). Plate XXX, Figs. 4, 4a, 4b. Pholas petrosa Conrad, 1842, Proc. Nat. Inst., Bull, ii, p. 193, pi. ii, fig. 4. Pholas petrosa Conrad, 1846, Amer. Jour. Sci., ser. ii, vol. i, p. 213, pi. i, fig. 1. Pholas petrosa H. C. Lea, 1848, Proc. Acad. Nat. Sci. Phila., vol. iv, p. 104. Pholas petrosa Conrad, 186.5, Amer. Jour. Conch., vol. i, p. 2. Pholas petrosa Conrad, 1866, Smith. Misc. Coll. (200), p. 9. Pholas 0) petrosa Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Pholas {‘i) petrosa Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 73, pi. xv, figs, la-lc. Phenacomya petrosa Dali, 1898, Trans. Wagner Free Inst. Sci., vol. iii, part iv, p. 823. Description. — Ovate-acute; anteriorly profoundly ventricose; radii sharp and numerous; dorsal margin obliquely rectilinear from the sum- mit of the umbo; base obliquely subrectilinear; posterior side produced, cuneiform.^^ Conrad, 1842. This form is apparently restricted to the limestone ledge, known as Zone 5. Length, 85 mm.; height, 35 mm. Occurrence . — Aquia Formation. “Piscataway’’ (Conrad), Fort Washington, Aquia Creek, Clifton Beach. Collections . — Johns Hopkins University, Maryland Geological Survey, Philadelphia Academy of Natural Sciences. Family GASTROCHAENIDAE. Genus GASTROCHAENA Spengler. Gastrochaena sp. Plate XXX, Fig. 5. Gastrochaena sp. Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Gastrochaena sp. Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 73, pi. xv, tig. 6. Casts of the tubes of Gastrochaena are common in the indurated layer. Zone 5, of the Aquia Creek stage, and also occur at higher horizons. 11 162 SYSTEMATIC PALEONTOLOGY Few of the specimens obtained show any traces of the shell substance^ and rarely impressions of the transverse striations of the tube wall. Occurrence. — Aquia Foemation. Aqnia Creek, Upper Marlboro. Collection . — Johns Hopkins University. Family SAXICAVIDAE. Genus PANOPEA Menard. Panopea elongata Conrad. Plate XXXI, Figs. 1-5. Panopaea elongata Conrad, 1885, Trans. Geol. Soc. Penn., vol. i, p. 339, pi. xiii, tig-. 1. Panopaea elongata Conrad, 1846, Amer. Jour. Sci., ser. ii, vol. i, p. 215, pi. i, tig:. 2.. Panopaea elongata H. C. Lea, 1848, Proc. Acad. Nat. Sci. Phila., vol. iv, p. 103. Glycyrnei'is elongata Conrad, 1854, Proc. Acad. Nat. Sci., Phila., vol. vii. p. 29. Glycymeris elongata Conrad, 1865, Amer. Jour. Conch., vol. i, p. 2. Glycymeris elongata Conrad, 1866, Smith. Misc. Coll. (200), p. 8. Panopaea elongata Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 4. Panopaea elongata Clark, Bull. 141, U. S. Geol. Survey, p. 75, pi. xix, tigs, la-lc. Panopea elongata Dali, 1898, Trans. Wagner Free Inst. Sci., vol. iii, pt. iv, p. 828. Description . — Shell oblong, produced, surface with distinct con- centric irregular undulations; beaks distant from the anterior margin.’’ Conrad, 1835. Since at most localities casts alone are found, the following important character has thus been overlooked, viz., that the surface is covered with closely-set, radiating lines of minute granules, which when worn show as lines of punctae, or give the surface an irregularly honeycombed ap- jiearance. Length, 85 mm.; width, 43 mm. Occurrence . — Aquia Foemation. Fort Washington, Winchester,. Piscataway ” (Conrad), Tinkers Creek 1 mile north of Piscataway, 1 mile northeast of Piscataway, 1 mile southeast of Mason Springs, Har- desty, E. E. cut near Seat Pleasant, Aquia Creek, Potomac Creek, Pas- potansa Creek, 2 miles below Potomac Creek, Marshall Hall, Upper ]\[arll)oro, Clifton Beach, Eolphs Landing, Glymont. Collections . — Johns Hopkins University, Maryland Geological Survey, Philadelphia Academy of Xatural Sciences, U. S. Xational Museum. MARYLAND GEOLOGICAL SURVEY 163 Family CORBULIDAE. Genus CORBULA Lamarck. CORBULA SUBENGONATA Dali. Plate XXXII, Figs. 1, la, 2, 2a, 2b. Corhula nasuta Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Corbula nasuta Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 74. Corhula suhengonata Dali, 1898, Trans. Wagner Free Inst. Sci., vol. ill, pt. iv, p. 841. Description . — This form is smaller, less inflated, thinner, and with more nearly parallel dorsal and ventral borders than C. alabamiensis. The sculpture is finer than in C. engonata, which is a more elongated species.^’ Dali, 1898. The species was thus defined by Dr. Dali to include the forms from the Chickasawan of Alabama, which had previously been called C. ala- bamiensis Lea or C. alabamiensis var. It is probably the ancestral form of the Claibornian C. alabamiensis Lea. This species is very common in the Maryland and Virginia Eocene. Its slightly elevated umbones and the absence of rostrated posterior sur- face separate it from the other species of this genus. In its occurrence it differs from our other Eocene species of Corbula in that it is most abundant in the lower beds. Length, 11 mm.; height, 6 mm. Occurrence. — Xanjemoy Formation. Woodstock, Popes Creek. Aquia Formation. Glymont, Clifton Beach, 6 miles east of Washing- ton, Mattawoman Creek, 2 miles below Potomac Creek, 1 mile southeast of Mason Springs, 1 mile northeast of Piscataway. Collectiojis . — Maryland Geological Survey, Johns Hopkins University, U. S. Xational Museum. Corbula aldrichi Meyer. Plate XXXII, Figs. 3, 3a, 4, 4a, 5, 5a, 6, 6a. Corhula aldrichi Meyer, 1885, Amer. Jour. Sci., ser. iii, vol. xxx, p. 67. Corhula aldrichi Aldrich, 1886, Bull, i, Ala. Geol, Survey, p. 83, pi. i, fig. 21. Corhula aldrichi Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Corhula aldrichi Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 74. Description. — It has radiating striae on the umbonial part of the surface, a characteristic which I had not seen before in a Corbula.” Meyer, 1885. 164 SYSTEMATIC PALEONTOLOGY Eoimded trigonal; ventricose; posterior side carinated; beak small, curved anteriorly, in the left valve nearly in the middle; right valve briefly rostrated; in both valves the nmbonial part is without concentric ribs, but with impressed, radiating lines — the ventral part with con- centric ribs.” Aldrich, 1886. This remarkable form, with its radiating lines upon the nmbonial portions of the shell, is very common. The Maryland form differs in no essential particulars from the Gulf type. Length, 11 mm.; height, 7 mm. Occurrence. — Nanjemoy Formation. Upper Marlboro (deep cut near Chesapeake Beach E. E. station). East and west of Port Tobacco, Head of Hanjemoy Creek, mile below Chapel Point, Popes Creek, IJ miles above Popes Creek, miles above Popes Creek, AVoodstock, 1 mile southeast of Piscataway. Aquia Formation. Aquia Creek, Liverpool Point, Clifton Beach. Collectio7is . — Maryland Geological Survey, Johns Hopkins University, U. S. National Museum. CoRBULA ONiscus Conrad. Plate XXXII, Figs. 7, 7a, 8, 8a, 8b. Corbula oniscus Conrad, 1833, Amer. Jour. Sci., vol. xxiii, p, 341. Corbula oniscus Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Corbula oniscus Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 75. Corbula {Aloiclis) oniscus Dali, 1898, Trans. Wagner Free Inst. Sci., vol. iii, pt. iv, p. 843. Description . — Shell elevated; larger valve ventricose, with profound sulci terminating at the nmbonial slope, which is carinated; posterior extremity narrowed and truncated, from the posterior angle of which a Carina extends to the apex, nearly parallel with that of the nmbonial slope; superior valve concentrically striated. Length, one-third of an inch.” Conrad, 1833. This species, characterized by its solid form and numerous concentric, wrinkled, approximate lines and prominently rostrated posterior sur- face, is common at several localities in the Maryland Eocene. None of the specimens obtained reach the size of the larger individuals in the Gulf Eocene. MAKYLAXD GEOLOGICAL SURVEY 165 Length, 10 mm.; height, 7 mm. Occurrence . — Nanjemoy Formation. East and west of Port Tobacco, Woodstock, Popes Creek, 2^ miles above Popes Creek, Head of Nanjemoy Creek, Upper Marlboro (deep cut near Chesapeake Beach K. E. station), 1 mile southeast of Piscataway. Hills Bridge? Aquia Formation. Glymont. Collection . — Maryland Geological Survey. Family SOLENIDAE. Genus SOLEN Linne. SoLEN LiSBONENSis (?) Aldrich. Plate XXXIII, Fig. 1. Solen Usbonensis Aldrich, 1886, Bull, i, Ala. Geol. Survey, p. 37, pi. iv, fig. I. Solen up. Harris, 1897, Bull. Amer. Pal. No. 9, p. 66, pi. xiv, fig. 9. Solen (Plectosolen) lisbonensis Dali, 1900, Trans. Wagner Free Inst. Sci., vol. iii, pt. v, p. 953. (.^) Solen {Plectosolen) lisbonensis var. abruptas Dali, 1900, Trans. Wagner Free Inst. Sci., vol. iii, pt. v, p. 953. Description . — Shell linear, nearly straight; posterior snbtruncate; anterior obliquely rounded with a depressed space behind running to the beaks; lines of growth prominent, bending at right angles along a line running obliquely from the beaks to the junction of the posterior and ventral margins. Anterior widely gaping.’^ Aldrich, 1886. The references given above are the only records we have of the occur- rence of this genus in the Eocene of Eastern Xorth America. The two specimens from the Potomac Eiver are both imperfect and neither shows any characters upon which they can be specifically separated from S. lishonensis. The lines of growth on our specimens do not bend quite as sharply as they do in AldricUs figure. In this respect they are more like the figure published by Professor Harris. Our specimens are smaller than either of those figured from Alabama. In the publication above noted. Dr. Dali describes a variety ahruptus under S. lishonensis. This differs from our form even more than the typical S. lishonensis does. 166 SYSTEMATIC PALEONTOLOGY Length (of fragment), 32 mm.; width, 9 mm. Occurrence . — Nanjemoy Fokmation. ^ mile below Chapel Point, Woodstock. Collections . — Maryland Geological Survey, Philadelphia Academy of Natural Sciences (No. 6224). Family TELLINIDAE. Genus TELLINA Deshayes. Subgenus ANGELUS Megerle. Tellina (Angelus) vieginiana Clark. Plate XXXIII, Pig. 3. Tellina virginiana Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Tellina virginiana Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 76, pi. xv, flg. 4. Tellina greggi Harris, 1897, Bull. Amer. Pal. No. 9, p. 72. (In part.) Tellina {Angelas) virginiana Dali, 1900, Trans. Wagner Free Inst. Sci., vol. iii, pt. V, pp. 1015, 1016. Description . — Shell elongated, thin, compressed; posteriorly very short, angular, and slightly folded; anteriorly rounded and elongated; umbones posteriorly situated; two small cardinal teeth and indistinct lateral teeth; pallial sinus obscure. Exterior covered with fine concen- tric lines following lines of growth.” Clark, 1896. This species is more abundant in the Nanjemoy formation, but the specimens from the Aquia formation are much larger. Professor Harris has suggested the identity of this form with T. greggi of Alabama, but further study has shown them to be undoubtedly dis- tinct. Dr. Dali agrees with us in this opinion. Length, 38 mm. (average, 18 mm.); height, 25 mm. (average, 13 mm.). Occurrence . — Nanjemoy Fokmation. Woodstock, Popes Creek, East and west of Port Tobacco, Charles Branch between Rosary ville and Up- per Marlboro, 2J and 3 miles above Popes Creek. Aquia Fokmation. Aquia Creek, Clifton Beach, 2 miles below Potomac Creek, 1 mile south- east of Mason Springs, Fort Washington. Collections . — Maryland Geological Survey, Johns Hopkins University. MAKYLAND GEOLOGICAL SURVEY 167 Section peronidia dale. Tellina (Peronidia ?) williamsi Clark. Plate XXXIII, Figs. 2, 2a. Tellina williamsi 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Tellina williamsi Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 76, pi. xv, figs. 3a, 36. Tellina subtriangularis Harris, 1897, Bull. Amer. Pal., No. 9, p. 73. (In part). Tellina {Peronidia?) williamsi Dali, 1900, Trans. Wagner Free Inst. Sci., vol. iii, . pt. V, p. 1016. Description. — Shell small, rather solid, not strongly inequilateral; posterior shorter; surface ornamented with elevated, close-set ridges or lamellae, increasing in size toward the basal margin; posteriorly suhan- gulated; two cardinal teeth, posterior bifid; lateral teeth strongly devel- oped; pallial sinus deep.’^ Clark, 1896. The question of the identity of this form with Tellina subtriangularis Aldrich of the Alabama Eocene has been carefully considered. Dr. Dali " agrees with us that they are distinct, but Professor Harris " thinks they are the same. T. williamsi is more elongate and more strongly sculptured. Length, 12 mm., height, 7 mm. Occurrence. — Xanjemoy Formation. Popes Creek, 2^ miles above Popes Creek, Woodstock. Aquia Formation. Potomac Creek. Collection. — Maryland Geological Survey, Johns Hopkins University. Tellina (Peronidia) p^pyria (?) Conrad. {?) Tellina papyria Conrad, 1833, Fossil Shells of the Tertiary, No. 4, p. 41 (lig’d. Amer. Jour. Sci., vol. i, 1846, pi. iv, tig. 7). A single specimen has been found which belongs to neither of the pre- ceding species, and which has the outline of T. papyria. The shell is very thin and has almost disappeared. Length, 35 mm.; height, 26 mm. Occurrence. — Aquia Formation. Fort Washington. Collection. — Maryland Geological Survey. * Trans. Wagner Free Inst. Sci., vol. iii, pt. v, 1900, p. 1016. ^Bull. Amer. Pal., No. 9, 1897, p. 73. 168 SYSTEMATIC PALEONTOLOGY Family VENERIDAE. Genus MERETRIX Lamarck. Meretkix lenis (Conrad). Plate XXXIII, Fig. 4. Cytherea lenis Conrad, 1S48, Jour, Acad. Nat. Sci. Phila., 2nd ser., vol. i, p. 180, pi. xiv, tig. 19. Description . — Longitndinally ovate, thin, ventricose; anterior ex- tremity acutely rounded; posterior end direct, snbtrnncated; disk with impressed concentric lines, distinct on the sides hut obsolete in the middle of the valves; lunnle long, cordate, defined by an impressed line; inner margin entire.^^ Conrad, 1848. This species is distinguished from its associates by its extremely ele- vated beaks, and deep valves. The shell is very thin and fragile and tends to break along radiating lines. The concentric wrinkles and lines of growth are very distinct toward the beak, hut become less so toward the periphery. Length, 11 mm.; height, 11 mm. Occurrence . — Xanjemoy Formation. Woodstock, Kavine north of Thrift (?). Collections . — Maryland Geological Survey, Philadelphia Academy of Natural Sciences (No. 6384). Meretrix ovata yar. ovata (Rogers). Plate XXXIV, Figs. 1, la. Cytherea ovata Rogers, 1837, Trans. Amer. Philos. Soc., vol. v, p. 340; vol. vi, pi. xxvii, fig. 2. (Reprint Geol. of the V'irginias, 1884, p. 668, pi. ii, fig. 2.) Cytherea liciata Conrad, 1848, Jour. Acad. Nat. Sci. Phila., 2nd ser., vol. i, p. 131, pi. xiv, fig. 20. Cytherea ovata H. C. Lea., 1848, Proc. Acad. Nat. Sci. Phila., vol. iv, p. 99. Cytherea liciata H. C. Lea, 1848, Proc. Acad. Nat. Sci. Phila., vol. iv, p. 99. Meretrix liciata Conrad, 1854, Proc. Acad. Nat. Sci. Phila., vol. vii, p. 30. Meretrix ovata Conrad, 1854, Proc. Acad. Nat. Sci. Phila., vol. vii, p. 30. Diove ovata Conrad, 1865, Amer. Jour. Conch., vol. i, p. 6. Bione liciata Conrad, 1865, Amer. Jour. Conch., vol. i, p. 6. Dione ovata Conrad, 1866, Smith. Misc. Coll. (200), p. 7. Bione liciata Conrad, 1866, Smith. Misc. Coll. (200), p. 7. Cytherea ovata Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. (In part.) Cytherea ovata Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 76. (In part.l MAEYLAXD GEOLOGICAL SURVEY 169 Description . — Shell suhovate, somewhat inflated, with concentric transverse striae, very fine near the nmhones, hnt much coarser near the margin; beaks rather elevated; Innnle very indistinct; teeth elevated and straight, the two posterior ones of the left valve small, much compressed, approximate, and nearly parallel; the anterior tooth large and grooved by a deep canal; cavity of shell deep; margin entire; posterior margin straight, and separated from the muscular impression by a fold or groove. Length one and one-tenth of an inch; height eighty-five hundredths of an inch.^’ Eogers, 1837. This widely-distributed species shows great variation in outline and has been described under several names, of which only the Maryland names are given in the synonymy. The complete species includes M. nuttalliopsis Heilprin with all its varieties, and a number of other Ala- bama names. The species ranges from the base to the summit of the Maryland Eocene, and is very abundant in nearly all localities. The two varieties may be clearly recognized and their separation closely confot-ms to the stratigraphic divisions. The form originally described by Eogers comes from the Xanjemoy formation. It is smaller, thinner, in general more elongate, and with a less rounded basal margin than the older type. It was this variety that Conrad afterward named liciata. Length, 31 mm.; width, 24 mm. Occurrence . — Xaxjemoy FoR^iiATiox. East and west of Port To- bacco, Popes Creek, 1 to 2^ miles above Popes Creek, ^ mile below Chapel Point, Upper Marlboro (deep cut near ^Chesapeake Beach E. E. station). Upper Marlboro (southwest of town near forks of roads). Head of Xanjemoy Creek, 1 mile southeast of Piscataway. Collections . — Maryland Geological Survey, Johns Hopkins University, Philadelphia Academy of Xatural Sciences, U. S. Xational Museum. Meretrix ovata VAR. PYGA Conrad. Plate XXXIV, Figs. 2, 2a, 3, 3a, 4, 5. Cythei'ea pyga Convady 184S, Jour. Acad. Nat. Sci. Pliila., 2nd ser., vol. i, p. 131, pi. xiv, flff. 18. Cytherea pyga II. C. Lea, 1848, Proc. Acad. Xat. Sci. Phila., vol. iv, p. 09. 170 SYSTEMATIC PALEONTOLOGY Meretrix pyga Conrad, 1854, Proc. Acad. Nat. Sci. Phila., vol. vii, p. 30. Dione pyga Conrad, 1865, Amer. Jour. Conch., vol. i, p. 6. Cytherea ovata Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. (In part.) Cytherea ovata Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 76 (In part), pi. xvi, figs. la-1/. Description. — Siiboval, ventricose, thick, with closely arranged ro- bust concentric lines; nnibo wide, prominent above; dorsal margin very oblique, rounded; posterior extremity obtusely and obliquely rounded inwards; anterior extremity much narrower than the posterior, and more acutely rounded; liinnle lanceolate, defined by a distinct impressed line; cardinal teeth robust. Length, If; height. If/’ Conrad, 1848. The form described by Conrad under this name was found in the Aqnia formation, and the name as here used is thus restricted. The specimens are large, thick, ventricose, and more nearly oval than the variety from the Nanjemoy formation. Length, 50 mm.; width, 43 mm. Occurrence. — Aqijia Foiimation. Potomac Creek, Aqnia Creek, Fort Washington, Glymont, Month of Paspotansa Creek, Liverpool Point, Sheckel’s Farm near South Eiver, Clifton Beach, 2 miles below Potomac Creek, 1 mile northeast of Grimesville, Upper Marlboro, Hardesty, Brooks Estate near Seat Pleasant, 2 miles west of Collington, Eeedy Eiin (branch of Chickomnxen Creek), Mattawoman Creek (?), 1 mile south- east of Mason Springs. Collections . — Maryland Geological Survey, Johns Hopkins University, Philadelphia Academy of Natural Sciences, U. S. National Museum. Meretkix subimpressa Conrad. Plate XXXIII, Figs. 5, 5a, 6, 7, 8, 8a, 9, 9a. Cytherea subimpressa Conrad, 1848, Jour. Acad. Nat. Sci. Phila., 2nd ser., vol. i, p. 130, pi. xiv, fig. 26. Cytherea subimpressa II. C. Lea, 1848, Proc. Acad. Nat. Sci. Phila., vol. iv, p. 99. Meretrix subimpressa Conrad, 1854, Proc. Acad. Nat. Sci. Phila., vol. vii, p. 30. Cytherea subimpressa CHv'k, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Cytherea subimpressa Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 77, pi. xvii, figs. la-17i. Description. — Ovate, slightly ventricose, smooth and polished, with concentric, slightly impressed lines on the anterior side; anterior side MAKTLAXD GEOLOGICAL SUETEY m short, rather acutely rounded; posterior side produced, acutely rounded at the extremity; dorsal margin long, oblique, slightly curved; beaks prominent; lunule lanceolate; defined by a slightly impressed line. Length, inch; height, 8-10 inch.’’ Conrad, 1848. This species is very abundant in the AVoodstock member of the Xan- jemoy formation. Length, 30 mm.; width, 18 mm. Occurrence. — Xaxjemoi: FoKiiATiox. Popes Creek, 1 mile southeast of Piscataway, AA'oodstock, Upper Marlboro (southwest of town near forks of two roads). Collections . — Maryland Geological Survey, Johns Hopkins University, Philadelphia Academy of Xatural Sciences. Genus DOSINIOPSIS Conrad Dosixiopsis LEXTicuLAKis (Eogers). Plate XXXA^, Figs, la-lg. Cytherea lenticularis'Rogevs, 1839, Trans. Amer. Philos. Soc., toI. vi, p. 372, pl.xxviii, tig. 1. Cytherea lenticularis H. C. Lea, 1848, Proc. Acad. Xat. Sci. Phila., vol. iv, p. 99. Artemis lenticularis Conrad, 1853, Proc. Acad. Nat. Sci. Phila., vol. vi, p. 320. Bosinia lenticularis Conrad, 1854, Proc. Acad. Nat. Sci. Phila., vol. vii, p. 30. Dosiniopsis meekii Conrad, 1864, Proc. Acad. Nat. Sci. Phila., vol. xvi, p. 213, and tigure in text. Dosiniopsis lenticularis Conrad, 1865, Amer. Jour. Conch., vol. i, p. 6. Dosiniopsis rneekii Conrad, 1865, Amer. Jour. Conch., vol. i, p. 6. Dosiniopsis rneekii Conrad, 1866, Smith. Misc. Coll. (200), p. 6. Dosmiopsis lenticularis Conrad, 1866, Smith. Misc. Coll. (200), p. 6. Dosiniopsis lenticularis Harris, 1894, Amer. Jour. Sci., ser. iii, vol. xlvii, p. 302. Dosiniopsis lenticularis Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Dosiniopsis lenticularis Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 78, pi. xviii, tigs, la-l^r. Description . — Shell large, depressed, discoidal, rather thick, length nearly equal to the breadth; transversely striated; lunule long, ovate, obscurely defined by a very faint impressed line; umbones rather de- pressed; beaks small, hardly recurved; teeth straight, divergent; cavity of the shell not deep; margin entire. Diameter about two inches.” Eogers, 1839. The type of the species, as figured and described by Eogers, is a much 172 SYSTEMATIC PALEONTOLOGY less common form than the variety later described by Conrad under the name of B. meekii. Eogers’s type represents a moderately thin shell with a weak hinge, while the form described by Conrad is a heavy shell with a broad, solid hinge. Every possible gradation between these extremes has been obtained. Length, 70 mm.; height, 70 mm. Occurrence. — Aquia Eoemation. Fort Washington, Glymont, Clif- ton Beach, Potomac Creek, Liverpool Point, Aqnia Creek, Mattawoman Creek, 1 mile northeast of Piscataway, Sheckels Farm near South Eiver, Eeedy Eun (branch of Chickomnxen Creek), 1 mile west of Hardesty, near Hardesty, Brooks Estate near Seat Pleasant, 1 mile northeast of Grimesville, Harrisons Landing, Upper Marlboro, 3 miles west of Pisgah, Fredericktown. Collections . — Maryland Geological Survey, Johns Hopkins University, U. S. National Museum, Philadelphia Academy of Natural Sciences. Family CARDIIDAE. Genus PROTOCARDIA Beyrich. Protocardia lenis Conrad. Plate XXXVI, Figs. 1, la, 2, 2a, 3. Cardinm {Protocardia) lenis Conrad, 1855, Proc. Acad. Nat. Sci. Pliila., vol. vii, p. 258. Protocardia virginiana Conrad, 1864, Proc. Acad. Nat. Sci. Pbila., vol. xv, p. 211. Protocardia virginiana Conrad, 1866, Smith. Misc. Coll. (200), p. 6. Protocardia virginiana Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Protocardia virginiana Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 81, pi. xxvi, tigs, la-lc. Protocardia lenis Dali, 1900, Trans. Wagner Free Inst. Sci., vol. iii, pt. v, p. 1113. Description . — Compared with C. nicolletti; nmho less inflated, pos- terior margin oblique, shell proportionally longer, and the radiating lines 22; in the other 25. The posterior cardinal tooth larger, &c.^^ Conrad, 1855. Cordate, snhtriangnlar, inequilateral, ventricose, thin; radiating lines minute; anterior upper margin very oblique, slightly emarginate, pos- terior side slightly produced, the margin obliquely truncated; post-nm- honal area densely tnhercnlated on closely arranged striae; posterior car- MARYLAND GEOLOGICAL SURVEY 173 dinal tooth small, tubercular. Height, 1-| inch; length. If inch." Conrad, 1864. This species has a wide vertical and horizontal range in the Maryland Eocene. It is hy no means a common form, and good specimens are very rare. Certain Gulf-state forms have been referred to this species, hut the recent work of Dr. Dali shows that they are distinct and that this species is apparently restricted to Maryland and Virginia. Length, 42 mm.; width, 42 mm. Occurrence . — Hanjemoy Formation. Popes Creek, Woodstock. Aquia Formation. Aquia Creek, Potomac Creek, 1 mile southeast of Mason Springs, 2 miles below Potomac Creek, Upper Marlboro, Eolphs Landing, 1 mile northeast of Piscatawa}^ mouth of Paspotansa Creek. Collections . — Maryland Geological Survey, Johns Hopkins University, Philadelphia Academy of Natural Sciences. Family DIPLODONTIDAE. Genus DIPLODONTA Broun. Diplodonta marlboroensis n. sp. Plate XXXVI, Fig. 4. Description . — Shell subcircular, moderately and regularly convex. Beaks depressed, approximate. Lines of growth weak. Surface irregu- larly wrinkled, sometimes smooth and almost polished. Differs from D. liopTcinsensis Clark in being larger, more elevated, much less globose, having a less prominent beak, and much weaker and less frequent lines of growth. This species has a resemblance to D. ungulifera Conrad. The resem- blance is especially close with Lea’s figure of that species (described as Egeria rotunda). Length, 18 mm.; width, 16 mm.; depth of valve, 4 mm. Occurrence . — Aquia Formation. Upper Marlboro, SlieckeFs Farm near South Eiver. Collection . — Maryland Geological Survey. 174 SYSTEMATIC PALEONTOLOGY Diplodonta hopkinsensis Clark. Plate XXXVI, Figs. 5, 5a, 6, 7. Biploclonta hopkinsensis Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Diplodonta hopkinsensis Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 79, pi. xxii, figs. la-lfZ. Diplodonta hopkitisensis Dali, 1900, Trans. Wagner Free Inst. Sci., vol. iii, pt. v, p. 1181. Description . — “ Shell small, suhorbicular, globose; surface with fine in- distinct striations; anteriorly and posteriorly rounded.’’ Clark, 1896. This species has not been found in Maryland, hut as it occurs in the same beds in Virginia it will undoubtedly he found in Maryland later, and for this reason the figures and description are reprinted for the benefit of future investigators. Dr. Dali records several localities in the Chickasawan of Alabama. Length, 16 mm.; height, 15 mm. Occurrence. — Xanjemoy Formation. Evergreen, Va. Collection . — Johns Hopkins University. Family LUCINIDAE. Genus LUCINA Bruguih'e. Lucina aquiana Clark. Plate XXXVII, Figs. 1, la. Lucina aquiana Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Lucina aquiana Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 78, pi. xx, figs, la, 16. {?) Lucina greggi Harris, 1897, Bull. Amer. Pal. No. 9, p. 70 (In part), pi. xiv, fig. 2a (not fig. 2). Description . — “ Shell of moderate size, somewhat compressed; surface covered with numerous concentric striae; umhones depressed and acumi- nate on account of prominent, deeply incised lunules; anterior side elon- gate; posterior side rounded; hinge with two cardinal and two lateral teeth.” Clark, 1896. The smaller figure published by Professor Harris of a specimen from Gregg’s Landing, Ala., is indistinguishable from this species. Length, 18 mm.; height, 18 mm. Occurrence . — Aquia Formation. Aquia Creek, Upper Marlboro. Collections. — U. S. Xational Museum, Maryland Geological Survey. MARYLAND GEOLOGICAL SURVEY 175 Lucina astartiformis Aldrich. Plate XXXA^II, Figs. 2, 2a. Lxicina astartiformis Aldrich, 1897, Bull. Amer. Pal. No. 8, p. 15, pi. v, figs. 1, la. Description . — “Shell small^ rather solid; beak pointed and small; sur- face with numerous concentric raised lamellae which nearly overlap at ventral margin; between the striae are fine radiating lines from beak to margin; striae terminating at hinge line in raised points; hinge long and narrow; anterior of shell concave along the hinge line; escutcheon smooth; cardinal teeth separated by a deep quadrangular fosset; no lat- erals; muscular impressions distinct; pallial line simple; posterior part of valves somewhat flattened; margin smooth.’^ Aldrich, 1897. The number of raised lamellae and the distance between them are very variable factors. This species is very rare. Length, 6 mm.; width, 5.5 mm. Occurrence. — XxVNJemoy Formation. 1 mile southeast of Piscata- way. Tapper Marlboro (deep cut near Chesapeake Beach R. R. station). Collection . — Maryland Geological Survey. Lucina dartoni Clark. Plate XXXA^II, Figs. 3, 3a, 3h. Lucina dartoni Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Lucina dartoni Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 79, pi. xx, figs. 2a~2c. Description . — “ Shell rather small, suhorhicular, thin; surface with fine, thin, distant concentric, lamellated striae, crossed by numerous radial, fine, irregular lines less distant than the concentric lamellae; an- teriorly and posteriorly high shouldered and angulated; lunules large; hinge area narrow; ligament small; muscle impressions shallow; margin simple.^’ Clark, 1896. Length, 9 mm.; width, 7.5 mm. Occurrence. — Xanjemoy Formation. Popes Creek, 24 miles above Popes Creek, Woodstock. Collections . — Johns Hopkins University, Maryland Geological Survey. 176 SYSTEMATIC PALEONTOLOGY Lucina uhleki Clark. Plate XXXVII^ Figs. 4, 5, 6, 7. Lucina ulileri Clark, 1895, Johns Hopkins Unii". Circ., yol. xv, p. 5. Lucina uhleri Clark, 189(5, Bull. 141, U. S. Geol. Survey, p. 79, pi. xxi, figs. la-\d. {?) Lucina ulrichi Harris, 1897, Bull. Amer. Pal. No. 9, p. 71, pi. xiv, fig. 4. Description . — Shell small, orbicular, slightly tumid; surface with nu- merous uniform, elevated, concentric ridges; anterior and posterior sides rounded; lunules slightly depressed; interior with radiating striae; mar- gin simple.^^ Clark, 1896. The original figures of this species did not show the muscular scars and the teeth accurately. The figures here published correct these de- fects. It is evident that Professor Harris has spelled the name ulrichi unin- tentionally. The form from Wood’s Bluff is probably the same as that from Maryland. The apparent difference in the hinge, noted by Pro- fessor Harris being an inaccuracy in the old figures which are here re- placed by a correct one. It would he a misfortune if we had to use two names, as nearly alike as uhleri and ulrichi, for two forms with as slight differences as these show. This is the most abundant and widely distributed of our Maryland Eocene Lucinas. The types are immature. Length, 9 mm.; height, 8 mm. Occurrence . — Xanjemoy Fokmation. Popes Creek, Woodstock. Aquia Fokmation. Clifton Beach, LTpper Marlboro, Potomac Creek, Glymont, 1 mile northeast of Piscataway, Mattawoman Creek, 1 mile southeast of Mason Springs, 2 miles below Potomac Creek, Liverpool Point. Collections . — Maryland Geological Survey, Johns Hopkins University. Lucina whitei Clark. Plate XXXVII, Figs. 8, 8a, 9. Lucina whitei Clark, 1895, Johns Hopkins Unix. Circ., vol. xv, p. 5. Lucina whitei Clark, 189G, Bull. 141, U. S. Geol. Survey, p. 79, pi. xx, ligs. 3«-3c. Description . — Shell small, suhorhicular, globose; surface with promi- nent concentric lamellae, interrupted posteriorly by shallow fold, extend- MARYLAND GEOLOGICAL SURVEY 177 ing from iimbones to posterior basal margin; Innules deeply depressed; anterior side high shouldered, rounded; posterior high shouldered, angu- lated; margin crenulated/’ Clark, 1896. Length, 8 mm.; width, 7.5 mm. 0ccurre7ice. — Nanjemoy Formation. IVest of Port Tobacco, ^ mile below Chapel Point, Woodstock. Collections. — Johns Hopkins University, Maryland Geological Survey. Lucina sp. A single fragment, evidently of a large Lucina, was found, which is very different from any other form known from Maryland or Virginia. It probably belongs to a new species of Lucina, or to L. claibornensis Con.; but our only specimen is too imperfect to determine. The shell is fragile, moderately thin, and the valves very shallow. It has about forty, rugose, concentric lamellae with faint, wavy, radiating lines be- tween them. Hinge, scars, and pallial line are unknown. Length and height about 30 mm. Occurrence. — Hanjemoy Formation. Popes Creek. Collection . — Maryland Geological Survey. Family CARDITIDAE. Genus VENERICARDIA Lamarck. This genus is very abundantly represented in the Maryland Tertiary and especially in the Eocene. The Eocene forms are very numerous and range throughout the entire horizontal and vertical extent of the forma- tions. The variation in form is very great and has led to the establish- ment of several species and varieties, all of which have been referred by most later authors to F. plaiiicosta. Three forms, possessing con- stant differences, ma}^ be recognized, and as these are each definitely restricted in stratigraphic range, and are hence of geologic value, they are given names. Rogers^ described from Virginia a species of Yejiericardia which he called F. ascia. As this form has never been recognized from Mary- 1 Trans. Amer. Philos. Soc., vol. vi, 1839, p. 374, pi. 29, fig. 2. 12 178 SYSTEMATIC PALEONTOLOGY land, no reference is made to it in the synonymy. If the figure and description are correct, it is probably a different species from any in Maryland. Venekicaedia planicosta vak. kegia Conrad. Plate XXXVIII, Figs. 1, la; Plate XXXIX, Figs. 1, la; Plate XL, Figs. 1, 2, 3. Cardita planico&ta Conrad, 1832, Fossil Shells of the Tertiary, No. 1, [1st. edit.] p. 20, pi. V, fig. 2. Cardita planicosta Morton, 1834, Syn. Org. Rem. Cretaceous Group, App., p. 7. Venericardia planicosta H. C. Lea, 1848, Proc. Acad. Nat. Sci. Phila., vol. iv, p. 107. Venericardia planicosta var. regia Conrad, 1865, Amer. Jour. Conch., vol. i, p. 8. Venericardia planicosta Conrad, 1866, Smith. Misc. Coll. (200), p. 5. Venericardia regia Conrad, 1866, Smith. Misc. Coll. (200), p. 5. Cardita planicosta Heilprin, 1884, Contrih. Tert. Geol. and Pal., p. 87. Venericardia planicosta var. regia Harris, Amer. Jour. Sci., ser. iii, vol. xlvii, p. 302. Venericardia planicosta Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Venericardia planicosta Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 80, pi. xxi, fig. 3 ; pi. xxii, fig. 2 ; pi. xxiii, figs, la (?) 15 (?) Ic; pi. xxiv, figs, la (?) 15 (?) Ic; pi. XXV, figs, la-lc. Description . — The form originally described and figured by Conrad, which he subsequently called V. regia, seems to correspond very closely to the original V. planicosta of Europe. Conrad describes it as follows: Cordate; ribs about 22, broad and flattened, separated by a narrow groove which becomes obsolete at the base; ribs near the posterior end narrow, indistinct, and crossed by numerous strong wrinkles; lunule small; cordate, profoundly impressed; inner margin crenate.’’ Conrad, 1832. This form is the largest of our Eocene Venericardias and is widely distributed in and restricted to the Aquia formation. It is readily dis- tinguished by its size, and its broad, flat ribs, which do not become obso- lete. Length, 110 mm.; width, 100 mm. Occurrence.— Aqm A Formation. Upper Marlboro, 1 mile west of Hardesty, Sheckels Farm near South Eiver, 1 mile northeast of Piscat- away, Xear Annapolis, Aquia Creek, Potomac Creek, Collington, Rolphs Landing, Mouth of Paspotansa Creek, Fredericktown (Cecil MAKYLAND GEOLOGICAL SURVEY 179 Comity), Fort IVashington, South Eiver at mouth of Broad Creek, Severn Eiver, Piscataway (Conrad’s original locality), 2 miles below Potomac Creek. Collections . — Maryland Geological Survey, Philadelphia Academy of Aatural Sciences, Johns Hopkins University, U. S. National Museum. Yenericardia marylandica n. sp. Plate XL, Figs. 7, 7a. Description . — Shell thin; outline circular; valves shallow; about 37 ribs, broad and flat on top, with deep, narrow interspaces near the beaks, but very flat, and separated by narrow, impressed line toward the peri- phery. This species resembles very closely in outline F. pectuncularis from the Paris Basin. It is restricted to the Woodstock substage. Length, 80 mm.; width, 80 mm. Occurrence. — Xanjemoy Formation. 2 and 2^ miles above Popes Creek, Popes Creek, Woodstock. Collection . — Maryland Geological Survey. Yenericardia potapacoensis n. sp. Plate XL, Figs. 4, 5, oa, 6, 6a. Description . — Shell small, very thick; valves relatively deep, and elon- gate along the line of the beak and posterior basal margin; beak an- teriorly situated; lines of growth strong; ribs 20 to 24 in number, ele- vated and crenulated toward the beak, and obsolete toward the periphery; lunule deeply impressed; muscular scars deeply impressed; margin strongly crenulate. This form is restricted to the Xanjemoy formation, and is most typically developed in the lower or Potapaco substage. Figure 4 repre- sents the typical Potapaco form. Figures 5 and 6 show the Woodstock form. Length, 40 mm.; width, 33 mm. Occurrence. — Xanjemoy Formation. East and west of Port Tobacco, Popes Creek, Woodstock, -J mile below Chapel Point, Head of Xanjemoy 180 SYSTEMATIC PALEONTOLOGY Creek, Potomac Creek (50 feet from top of bluff), 1 mile southeast of Piseataway, La Plata, Upper Marlboro (gully southwest of town), 2 and 2J miles above Popes Creek. Collections . — Maryland Geological Survey, U. S. National Museum, Philadelphia Academy of Natural Sciences. Family CRASSATELLITIDAE. Genus CRASSATELLITES Kruger. Ceassatellites alaefoemis (Conrad). Plate .XLI, Figs. 1-8. Crassatella alaeformis Conrad, 1830, Jour. Acad. Nat. Sci. Phila., vol. vi, p. 228, pi. X, fig. 1. Crassatella alaeformis Morton, 1834, Syn. Org. Rem. Cretaceous Group, App., p. 7. Crassatella capri-cranium. Rogers, 1839, Trans. Am. Phil. Soc., new series, vol. vi, p. 375, pi. XXX, fig. 2. (Reprint: Geology of the Virginias, 1884, p. 672, pi. V, fig. 2.) Crassatella alaeformis Conrad, 1846, Amer. Jour. Sci., ser. ii, vol. i, p. 396, pi. iii, fig. 3. (?) Crassatella pahnula Conrad, 1846, Amer. Jour. Sci., ser. ii, vol. i, p. 396, pi. iv, fig. 1. Crassatella alaeformis H. C. Lea, 1848, Proc. Acad. Nat. Sci. Phila., vol. iv, p. 98. Crassatella capri-cranium H. C. Lea, 1848, Proc. Acad. Nat. Sci. Phila., vol. iv, p. 98. Crassatella alaeformis d’Orbigny, 1850, Prodrome, vol. ii, p. 383. Crassatella capri-cranium Conrad, 1865, Amer. Jour. Conch., vol. i, p. 10. Crassatella alaeformis Conrad, 1865, Amer. Jour. Conch., vol. i, p. 10. Crassatella alaeformis Conrad, 1866, Smith. Misc. Coll. (200), p. 5. Crassatella capri-cranium Conrad, 1866, Smith. Misc. Coll. (200), p. 5. Crassatella declivis Heilprin, 1880, Proc. U. S. Nat. Museum, vol. iii, pp. 151, 152, pi. facing p. 150, fig. 9. Crassatella protexta de Gregorio, 1890, Ann. Geol. et Pal., pi. xxv, fig. 12. Crassatella alaeformis Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Crassatella alaeformis Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 81, pi. xxvii, figs, ia-lk. (?) Crassatella pal mula Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 93. Crassatella declivis Aldrich, 1897, Bull. Amer. Pal. No. 8, p. 4, pi. iii, figs. 1, la. Description . — Shell transversely ovate oblong; anterior side ros- trated; posterior side short and rounded; umbones transversely sulcated; margin slightly crenulated within.’’ Conrad, 1830. The variations in C. alaeformis Conrad are so great that in the ab- sence of connecting forms one would be led to consider the existence of several well-defined species. After a careful study of a large amount of MARYLAND GEOLOGICAL SURVEY 181 material belonging to this important species, it appears that the forms figured and described by Eogers and Heilprin as distinct species are only varieties of Conrad’s C. alaefoiinis. The species is largely represented in the lower portion of the Middle Atlantic Coast series, especially in the Piscataway snbstage of the Aqnia formation. It is rarer in the Pas- potansa snbstage, and here two distinct forms are found, each different from the older forms. The specimens from the sandy beds along the Potomac are small and very elongate, the average size being 40 x 20 mm. The indurated ledge at Upper Marlboro, Hardesty, South Eiver bridge, and Eolphs Landing contains a very large form at the other end of the alaeformis series. This reaches the size and proportions of 90 x 60 mm., but a single specimen from South Eiver, which may however belong to another species, attains the size of 95 x 80 mm. The larger elongate forms approach the several Miocene species in size and outline. The specimens from the various beds of the Piscataway substage vary greatly in size and form and connect the Paspotansa varieties with each other and almost connect them with C. aquiana. C. palmula Conrad prob- ably belongs in this series. Length, 40 to 90 mm.; height, 20 to 60 mm. Occurrence. — Aquia Formation. Paspotansa Creek, 2 miles below Potomac Creek, Potomac Creek, 1 mile southeast of Mason Springs, Clif ton Beach, Clymont, Mattawoman Creek, Liverpool Point, Wades Bay, Aquia Creek, 1 mile northeast of Piscataway, Brooks Estate near Seat Pleasant, Fort Washington, Upper Marlboro, 3 miles west of Leeland on Western Branch, West of Collington, between Buena Vista and Colling- ton, SheckeFs Farm near South Eiver, Eolphs Landing. Collections. — Maryland Geological Survey, Johns Hopkins University, U. S. National Museum, Philadelphia Academy of Natural Sciences. Crassatellites aquiana (Clark). Plate XIJI, Figs. 1, 2a, 2b. CrciHmtella aquiana Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Crassatella aquiana Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 82, pi. xxvi, figs. 2a-Zc. Description . — Shell moderately large, attenuated posteriorly; surface w4th a few broad, shallow, concentric furro\vs, indicating periods of 182 SYSTEMATIC PALEONTOLOGY growth, and fine concentric lines, often obscure; Innules broad, deeply depressed. This species differs from C. alaeformis by its shorter, broader pos- terior extremity; by the absence of deep, prominent furrows on the nm- bones, and by the nmbones themselves being higher.’^ Clark, 1896. This species shows considerable variation in size and form, sometimes approaching the more elevate varieties of C. alaeformis. On the other hand it frequently becomes so short and elevate as to approach Astarte in outline. This species is most abundant in the Piscataway substage. Length, 60 mm.; height, 50 mm. Occurrence. — Aquia Formation. Aqnia Creek, Glymont, Eeedy Kun, Brooks Estate near Seat Pleasant, Potomac Creek, Liverpool Point, Mat- tawoman Creek. Collections . — Maryland Geological Survey, Johns Hopkins University, Philadelphia Academy of Natural Sciences. Crassatellites ALTA (Conrad). Plate XLII, Fig. 3. Crassatella alia Conrad, 1832, Fossil Shells of the Tertiary, No. 2, p. 21, pi. vii. Crassatella alia Conrad, 1835, Trans. Geol. Soc. Penn., vol. i, p. 335. Description . — Snboval, thick and ponderous, compressed; anterior margin obtusely rounded; posterior margin broad and slightly angular; beaks with regular concentric grooves, and somewhat angnlated behind; inner margin crennlated.^^ Conrad, 1832. Conrad recorded this species from Upper Marlboro in 1835, but there is no other evidence of its occurrence at that locality. The large speci- men here figured is from Hardesty and can belong to no other known species. The large forms alluded to under C. alaeformis may be the same as the Upper Marlboro forms which Conrad referred to C. alta. Length (of fragment), 105 mm.; width, 75 mm. Occurrence. — Aquia Formation. Hardesty. Collection . — Maryland Geological Survey. MARYLAND GEOLOGICAL SURVEY 183 Crassatellites sp. Plate XLII, Figs. 4, 4a. The specimen figured possesses characters very different from any other known species of the genns and if normal mnst he new, although it is perhaps only a diseased specimen of C. alaeformis. Length, 20 mm.; width, 13 mm. Occurrence. — Aquia Formation. Clifton Beach. Collection . — Johns Hopkins University. Family ASTARTIDAE. Genus ASTARTE Sowerby. Astarte marylandica Clark. Plate XLII, Fig. 5. Astarte marylandica Clark, 1895, Johns Hopkins Univ. Circ., vol. xy, p. 5. Astarte marylandica Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 80, pi. xxi, flg. 2. Description . — Shell small, ronndedly trigonal, somewhat compressed, thick, nearly equilateral; surface concentrically costated and with super- imposed fine striae; nmhones prominent.^’ Clark, 1896. Length, 16 mm.; width, 15 mm. Occurrence. — Aquia Formation. Upper Marlboro, Brooks Estate near Seat Pleasant, SheckeFs Farm near South Elver. Collections. — Johns Hopkins University, Maryland Geological Survey. Family PLEUROPHORIDAE. Genus CORALLIOPHAGA Blainville. Subgenus ORYCTOMYA Dali. CORALLIOPHAGA (Oryctomya) bryani Clark. Plate XLIII, Figs. 1, la, 2, 2a. Coralliophaga hryani Clark, 189.5, Johns Hopkins Univ. Circ., vol. xv, p. 5. Coralliophaga hryani Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 73, pi. xv, figs. 2a, 26. Description. — “ Shell transversely oblong, thin, slightly gaping pos- teriorly; prominent fold from umbo to lower margin; surface with deli- 184 SYSTEMATIC PALEONTOLOGY cate lines of growth and fine radial rows of minute grannies, obsolete over mnch of the surface; teeth consisting of two small cardinal and one long posterior lateral; pallial line with shallow sinus/^ Clark, 1896. Only two specimens, both right valves, have been found. The one here newly figured is smaller than the type, but more nearly perfect. The teeth are not well preserved, but the radiating rows of grannies show the generic affinities. Length, 20 mm.; height, 16 mm. Occurrence . — Aquia Formation. 1 mile southeast of Mason Springs, Pomonkey Neck. Collections . — Maryland Geological Survey, U. S. National Mnsenm. Order ANOM ALODESM ACEA. Family PERIPLOMIDAE. Genus PERIPLOMA Schumacher. Periploma (?) sp. Two specimens have been found which have the general form of this genns, but are too imperfect for complete identification or description. Length, 29 mm.; height, 24 mm. Occurrerice. — Nanjemoy^ Formation. East of Port Tobacco, Wood- stock. Collections . — Maryland Geological Survey, Philadelphia Academy of Natural Sciences (No. 6430). Family PHOLADOMYIDAE. Genus PHOLADOMYA Sowerby. Pholadomya marylandica Conrad. Plate XLIII, Fig. 3. Pholadomya marylandica Conrad, 1843, Proc. Nat. Inst. Bull, ii, p. 193, pi. i, fig. 3. Pholadomya marylandica Conrad, 1846, Amer. Jour. Sci., ser. ii, vol. i, p. 214, pi. ii, fig. 9. Pholadomya marylandica IT. C. Lea, 1848, Proc. Acad. Nat. Sci. Phila., vol. iv, p. 104. Pholadomya marylandica Conrad, 186.5, Amer. Jour. Conch., vol. i, p. 3. Pholadomya marylandica Conrad, 1866, Smith. Misc. Coll. (300), p. 8. Pholadomya marylandica Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Pholadomya marylandica Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 75, pi. xxix,. fig. 3. MAKYLAND GEOLOGICAL SUKVEY 185 Description. — OA^ate, profoundly ventricose, with coarse, irregular concentric lines and furroAvs, and obsolete, rather distant, radii; sum- mit of umbo prominent/’ Conrad, 1812. The very fragile shell of this species Avas found only partially pre- serA^ed in a feAv instances, although numerous casts Avere obtained from the indurated layer. Zone 5, at Aquia Creek. Length, 75 mm.; height, 55 mm. Occurrence . — Aquia Fokaiation. Clifton Beach (upper indurated bed), Aquia Creek, Fort Washington, PiscataAAmy (Conrad). Collections . — Maryland Geological Survey, Philadelphia Academy of Xatural Sciences, Johns Hopkins University, U. S. National Museum. Order PRIONODESMACEA. Family MYTILIDAE. Genus MODIOLUS Lamarck. Modiolus alabaaiensis Aldrich. Plate XLIII, Figs. 4, 5, 5a. Jfodiola alabamensis Aldrich, 1895, Bull. Amer. Pal. No. y, p. 16, nl. v, fig. 13. Modiola poto7nacensis Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Jlodiola potomaceiisis Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 85, pi. xxxiv, figs, la-lc. Modiolus {Bi'ccchijdontes) potomacensis Dali, 1898, Trans. AVagner Free Inst. Sci., vol. iii, pt. iii, p. 796. Description . — Shell strongly arcuate, surface with raised lines closely set, becoming nearly obsolete on the beaks; a few lines of growth cross- ing the striae; beak small, hinge margin slightly curved, ascending; very small fissure on basal margin.” Aldrich, 1895. Shell small, oblong, thin, tumid, anterior side someivliat contracted; surface Avith fine costated striae nearly obsolete anteriorly and less strongly accentuated posteriorly than in the center, crossed occasionally by irregular lines of growth; umbones prominent, curved. Length, 32 mm.; width, 15 mm. Occurrence . — Xanjeaioy Foraiation. Popes Creek, Woodstock, 2.1 miles aboA^e Popes Creek. Aquia Foraiation. Liverpool Point, Clif- 186 SYSTEMATIC PALEONTOLOGY ton Beach, Wades Bay, Aqnia Creek (Zones 2 and 3), Potomac Creek, 2 miles below Potomac Creek, Glymont, 1 mile southeast of Mason Springs, Upper Marlboro, Fort Washington, Month of Paspotansa Creek. Collections . — Maryland Geological Survey, Johns Hopkins University, U. S. National Museum, Philadelphia Academy of Natural Sciences. Modiolus makylandicus n. sp. Plate XLIII, Fig. 6. Description . — Shell thin and fragile; beaks elevated, strongly incurved, and situated far back of the anterior extremity; surface marked by strong lines of growth and faint radiating lines, developing into strong radial cracks. One specimen only, and that showing parts of both valves, has been found; while another that may belong to this species, although it shows some quite different characteristics, was also obtained. Length (of fragment), 20 mm.; width, 10 mm. Occurrence. — Nanjemoy Fokmation. Woodstock. Collectio7i . — Maryland Geological Survey. Genus LITHOPHAGA Bolten. Lithophaga makylandica n. sp. Plate XLIII, Fig. 7. Solemya petricoloides Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Soleniya petricoloides Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 74. Not By ssomy a petricoloides Lea. Description . — Shell elongated, very inequilateral, slightly gaping, thin; surface nearly smooth tvith fine lines of growth; umbones very posteriorly situated; hinge edentulous; pallial line obscure.’^ Clark, 1896. Our specimens differ from petricoloides in having the beaks nearly terminal. Length, 11 mm.; width, 4.5 mm. Occurrence . — Aquia Formation. Clifton Beach. Collections . — Maryland Geological Survey, Johns Hopkins LBiiversity. MARYLAND GEOLOGICAL SURYEIT 187 Family ANOMIIDAE. Genus ANOMIA Muller. Anomia maeytlandica n. sp. Plate XLIV, Figs. 3, 3a, 3. Description. — Shell small, thin, irregular; valves very unequal; right valve moderately and uniformly convex; hyssal opening small; left valve very convex and irregular. Beak anteriorly situated and much in- curved. Surface marked by fine raised radiating threads and irregular wavy concentric undulations. Lines of growth strong, irregular. Length, 19.5 mm.; height, 18 mm. Occurrence. — Xanjemoy Formation. Woodstock, Popes Creek. Aquia Formation. Clifton Beach. Collection . — Maryland Geological Survey. Anomia McGeei Clark. Plate XLIV, Figs. 1, la. (?) Anomia ruffini Conrad, 1835, Fossils Medial Tertiary, p. 74, pi. xlii, lig. 6. Aiiomia mcgeei Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Anomia mcgeei Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 86, pi. xxxiv, figs. 5a, 56. {?) Anomia ruffini Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 93. A7iomia ruffini Dali, 1898, Trans. Wagner Free Inst. Sci., vol. iii, pt. iv, p. 782. (In part). Description . — Shell of left valve rather solid, convex, nearly equi- lateral; surface strongly lamellar, with faint radial plaits, stronger in the latter than in the earlier portions of the shell.’^ Clark, 1896. The type of this species, which is the only adult specimen known, was found in the collections of the Philadelphia Academy of Natural Sciences labelled “Eocene of Hanover County, Ya.’^ Anomia ruffini Conrad was described with Miocene fossils (the type having been found on the Pamunkey Eiver, Virginia, where both Eocene and Miocene strata occur), and, was later, by Conrad and by others, placed in lists of both Eocene and Miocene forms. It is extremely doubtful if the species has ever been found in the Eocene. The resemblance between A. mcgeei and A. ruffini is so close and both are so different from any other forms which have ever been found 188 SYSTEMATIC PALEONTOLOGY in the Eocene that it is possible that they both represent the same Miocene species. Dr. Dali considers them identical but is in donht as to the horizon from which they came. It seems best to publish here the original figures of A. mcgeei under the original name in order to bring the question before the eyes of future investigators. Length, 50 mm.; height, 48 mm. Occurrence . — Hanover County, Ya. Collection . — Philadelphia Academy of Natural Sciences. Family PECTINIDAE. Genus PECTEN Muller. Pecten choctavensis Aldrich. Plate XLIV, Pigs. 4, 5, 6. Fecten choctavennis Aldrich, 1895, Bull. Amer. Pal. No. 2, p. 16, pi. v, fig. 7. Description . — Shell suhorhicular thin, depressed, finely closely rib- bed, ribs showing through the substance of the shell, imbricated near the ventral margin and on the anterior slope; ears ribbed and ribs im- bricated with fine oblique reticulations between.” Aldrich, 1895. There are 40 to 50 ribs, which are lamellated, especially when old, but sometimes when very young. The young shells from Alabama do not show any lamellation. The ribs increase both by bifurcation and intercolation. Camptonectes structure is a constant characteristic. Width, 23 mm.; height, 24 mm. Occurrence. — Nanjemoy Fokmation. Popes Creek, miles above Popes Creek. Aquia Formation. Upper Marlboro, 1 mile northeast of Piscataway, South East Creek (1 mile from Chester Eiver). Collection . — Maryland Geological Survey. Pecten dalli Clark. Plate XLIV, Figs. 7, 7a, 7b. Pecten rogersi Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Fecten rogersi Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 85, pi. xxxiv, figs. 2a-2c. Pecte7i dalli Clark, 1898, Johns Hopkins Univ. Circ., vol. xviii, p. 18. Fecteix {Fsendamusinm) frontalis Dali, 1898, Trans. Wagner Free Inst. Sci., vol. iii, pt. iv, p. 753. Not FectcM rogersi Conrad. MAKYLAXD GEOLOGICAL SURVEY 189 Descri'ption. — Shell small, orbicular, siibpellucid, nearl}^ equilateral, thin; surface shining with fine, delicate concentric lines and rather ob- scure, in places obsolete, radial ribs that show most strongly near the anterior margins; umbones approximate and acute; auricles very un- equal and costated/^ Clark, 1896. This very beautiful species shows some points of similarity to P. cal- vatns Conrad in form and surface features, but the radial striae are lack- ing upon the latter. It differs from P. choctavensis in its feebler sculp- ture. It possesses a faint camptonectes structure. Width, 16 mm.; height, 18 mm. Occurrence. — Hanjemoy Formation. Woodstock, Upper Marlboro (deep cut near Chesapeake Beach E. E. station). Aquia Forma- Tiox. Potomac Creek, South East Creek (1 mile above Chester Eiver). Collections . — Johns Hopkins University, Maryland Geological Survey. Pectex johnsoni Clark. Plate XLIV, Figs. 8, 8a. Pecten johnsoni Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, i). 5. Pecten johnsoni Clark, 1896, Bull. 141, U. S. Geol. Survey, j). 85, pi. xxxiv, flgs. 3fl[, 36. Description . — Shell small, suborbicular, equilateral; surface with about twenty uniform, distant, rounded costate, separated by broad interspaces, with a few short costae at basal margin, the whole crossed by fine lines of growth; ears prominent, unequal.^’ Clark, 1896. P. greggi Harris resembles this form very closely. It differs in hav- ing stronger camptonectes structure, and in not having the number of ribs increase toward the periphery. Width, 14 mm.; height, 15 mm. Occurrence. — Haxjemoy Formatiok. AYoodstock. Aquia Forma- Tiox. 2 miles below Potomac Creek, Potomac Creek, Mouth of Paspo- tansa Creek. Collections. — Johns Hopkins University, Maryland Geological Survey. 190 SYSTEMATIC PALEONTOLOGY Pecten sp. Plate XLIV, Figs. 9^ 9a. Pecten sp. Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Pecten sp. Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 86, pi. xxxiv, fig. 4. Description . — Shell small, orbicular; surface with about twenty broad, flat costae, dividing in most cases in passing downward, so that over thirty appear at the margin; umbones compressed; ears unequal.^^ Clark, 1896. This differs from P. jolinsoni only in having the ribs increase by bifurcation instead of intercolation, and in having the ribs broader than the interspaces. As the figured specimen is the only one that has been found and is very immature it is best not to give it a name. Perhaps it is an aberrant or immature form of P. jolinsoni, or of P. walitubheanus Dali. Width, 10 mm.; height, 11 mm. Occurrence. — Aquia Formation. Potomac Creek. Collection . — Maryland Geological Survey. Family OSTREIDAE. Genus OSTREA Linne. OsTREA compressirostra Say. Plates XLV, XLVI, XLVII. Ostrea compressirostra Say, 1824, Jour. Acad. Nat. Sci. Phila., vol. iv, p. 132, pi. viii, figs. 2a, 26 [Reprint Bull. Amer. Pal. No. 5, p. 38, pi. viii, figs. 2a, 26.] Ostrea compressirostra Morton, 1834, Syn. Org. Rem. Cretaceous Group, App., p. 2. Ostrea smuosa Rogers, 1837, Trans. Amer. Philos. Soc., vol. v, p. 340; vol. vi, pi. xxvii, fig. 1. Ostrea compressirostra H. C. Lea, 1848, Proc. Acad. Nat. Sci. Phila., vol. iv, p. 103. Ostrea hellovacina Conrad, 1842, Proc. Nat. Inst., Bull, ii, p. 172 (not of Lamarck). Ostrea smuosa H. C. Lea, 1848, Proc. Acad. Nat. Sci. Phila., vol. iv, p. 103. Ostrea compressirostra Conrad, 1865, Amer. Jour. Conch., vol. i, p. 15. Ostrea sinuosa Conrad, 1865, Amer. Jour. Conch., vol. i, p. 15. Ostrea compressirostra Conrad, 1866, Smith. Misc. Coll. (200), p. 3. Ostrea compressirostra Heilprin, 1883, White’s Fossil Ostreidae ; Fourth Ann. Rept. U. S. Geol. Survey, p. 309, pi. Ixv, figs. 1, 2. Ostrea coynpressirostra Heilprin, 1884, Contrib. Tert. Geol. and Pal., p. 85. Ostrea sinuosa Rogers, 1884, Geology of the Virginias, p. 668, pi. ii, fig. 1. Ostrea compressirostra de Gregorio, 1890, Ann. Geol. et Pal., t. ii, p. 177, pi. xx, figs. 1, 8. MARYLAND GEOLOGICAL SURVEY 191 Ostrea compressiroslra Harris, 1894, Amer. Jour. Sci., ser. iii, vol. xlvii, p. 302. Ostrea compressirosira Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Ostrea comprensirostra Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 86, pi. xxxvii, figs. 1, 2tt-2c; pi. xxxviii, figs, la, 16, 2a-2c; pi. xxxix, figs. 1, 2a, 26; pi. xl, flg- 1- Ostrea compressirosira Dali, 1898, Trans. Wagner Free Inst. Sci., vol. iii, pt. iv, p. 679. Description. — Shell sinistral;, siibovate: inferior valve convex, with iiiiineroiis convex ribs interrupted by fornicated scales at the lines of increment; hinge curving a little upward, very mnch contracted and short: superior valve flat, wrinkled concentrically, without any appear- ance of longitudinal lines: hinge more dilated than that of the superior valve, and oblique with respect to the thickness of the shell/^ Say, 1824. This is one of the most abundant fossils in the Aquia formation. The Xanjemoy formation contains many small oysters which are probably the young of sellaeformis, although they cannot be distinguished from the young of this species. Length, 215 mm.; width, 180 mm. Occurrence. — Aquia Formation. Upper Marlboro, Hardesty, Aquia Creek, Brooks Estate near Seat Pleasant, 3 miles west of Leeland on Western Branch, SheckeFs Farm near South Eiver, Keedy Kun, Liver- pool Point, IJ miles south of Grimesville, Potomac Creek, Fort Wash- ington, Tinkers Creek, 1 mile northeast of Piscataway, Swan Creek (ravine near Piscataway Creek), 1 mile southeast of Mason Springs, Mouth of Paspotansa Creek, Wades Bay, 3 miles west of Pisgah, Clifton Beach, Mattawoman Creek, 2 miles south of South Eiver, Glymont, 2 miles below Potomac Creek, Leeland, Seven Eiver. Collections. — Maryland Geological Survey, Johns Hopkins University, U. S. Xational Museum, Philadelphia Academy of Xatural Sciences. Ostrea compressirostra var. alepidota Dali. Ostrea compressirostra var. alepidota Dali, 1898, Trans. Wagner Free Inst. Sci., vol. iii, part iv, p. 680. Description. — AVithout raised lamellae externally but with radial grooves.^^ Dali, 1898. 192 SYSTEMATIC PALEONTOLOGY Shell small^ roughly triangular; beak high, in some cases slightly twisted; raised lamellae absent or confined to the extreme periphery; radial grooves, becoming stronger toward the periphery. Length, 85 mm.; width, 65 mm. Occurrence. — Aquia Formation. Fort Washington, Aquia Creek. Collections. — Maryland Geological Survey, V. S. National Museum, Philadelphia Academy of Natural Sciences. OsTREA SELLAEFORMis Conrad. Plates XLVIII, XLIX. Ostrea sellaeformis Conrad, 1832, Fossil Shells of the Tertiary, No. 2, p. 27, pi. xiii, fig. 2. Ostrea sellaeformis Morton, 1834, Syn. Org. Rem. Cretaceous Group, App., p. 6. Ostrea sellaeformis Conrad, 1842, Proc. Nat. Inst., Bull, ii, pp. 192, 193, pi. i, fig. 1. Ostrea sellaeformis H. C. Lea, 1848, Proc. Acad. Nat. Sci. Phila., vol. iv, p. 103. Ostrea sellaeformis Conrad, 1865, Amer. Jour. Conch., vol. i, p. 15. Ostrea sellaeformis Conrad, Smith. Misc. Coll. (200), p. 3. Ostrea sellaeformis 1883, White’s Fossil Ostreidae ; Fourth Ann. Rept. U. S. Geol. Survey, p. 311, pi. Ixii, figs. 1, 2 ; pi. Ixiii, fig. 1. Ostrea sellaeformis Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Ostrea sellaeformis Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 87, pi. xxxv, figs. la-l(Z; pi. xxxvi, figs, la, 16. Description. — Oblong, convex, thick and ponderous, lohed; one side of the larger valve profoundly sinuous and the opposite side gibbous; smaller valve sinuous and little convex; dorsal margin long and slightly arched, with both extremities obtusely rounded.” Conrad, 1833. This form although very abundantly and characteristically developed in the valleys of the James and Pamunkey rivers, occurs generally in the Potomac Valley and farther north only as small specimens, almost indistinguishable from the young of 0. compressirostra. Height, 60 mm.; width, 40 mm. (largest Maryland specimen). Occurrence. — Nanjemoa^ Formation. Popes Creek, 1-J miles above Popes Creek, 2J miles above Popes Creek, East of Port Tobacco, Upper Marlboro (deep cut near Chesapeake Beach B. E. station), Woodstock. Collections. — Johns Hopkins University, Philadelphia Academy of Natural Sciences, Maryland Geological Survey. MAKYLAXD GEOLOGICAL SUKVEY 193 Subgenus GRYPH AEOSTREA Conrad. OSTREA (GrYPHAEOSTREA) TOMER (Mortoil). Plate Figs. 1, la, lb, 2, 3, 4, 4a, 5. Gryphaea vomer Morton, 1830, Jour. Acad. Nat. Sci. Pliila., vol. vi (1st series), p. 83, Gryphaea vomer Morton, 1834, Syn. Org. Rem. Cretaceous, p. 54, pi. ix, tig. 5. Gryphaea vomer Conrad, 1835, Trans. Geol. Soc. Penn., a^oI. i, p. 336. Gryphaea vomer Conrad, 1842, Proc. Nat. Inst., Bull, ii, p. 172. Ostrea {Gryphaeostrea) subeversa Conrad, 1865, Amer. Jour. Conch., vol. 1, p. 15 (name only). Ostrea sp. Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 6. Ostrea sp. Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 88, pi. xxxix, tigs. 3a-3c. Ostrea subeversa Clark, 1896, Bull. 141, U. S. Geol, Survey, p. 93. Ostrea {Gryphaeostrea) subeversa Dali, 1898, Trans. Wagner Free lust. Sci., vol. iii, pt. iv, p, 681. Description . — “ Oblong-oval, thin, narrow; lower valve deep, longi- tudinally curved; beak prominent, curved laterally; upper valve small in proportion to the lower, and marked with distinct, concentric, squamose plates ” Morton, 1834. The possible equivalence of this form with Gryphaea vomer Morton, or Gryphaea eversa Mellville was suggested by Dali. Conrad recorded the species from Piscataway and Upper Marlboro. Length, 39 mm.; width, 20 mm.; depth of lower valve, 10 mm. Occurrence. — Nanjemoy Formation. mile below Chapel Point. Aquia Formation. Piscataway, Upper Marlboro, Aquia Creek, Po- tomac Creek, 2 miles below Potomac Creek, Sheckel’s Farm near South River, Fredericktown, Glymont. Collections . — Maryland Geological Survey, Johns Hopkins University, Philadelphia Academy of Natural Sciences. Genus GRYPHAEA Lamarck. Gryphaea vesicularis Lamarck. Plate L, Figs. 6, 6a. Gryphaea vesicularis Lamarck, 1806, Ann. Mus. viii, p. 160, pi. xxii, flg. 3. An. Sans. Vert., vol. vi, p. 209. A single specimen of this form was found associated with Eocene fossils at Clifton Beach. It is very perfect, having both valves in posi- tion. It seems hardly possible, however, that it can be a representative 13 194 SYSTEMATIC PALEONTOLOGY of the Eocene fauna, as an isolated specimen of this typical Cretaceous species, it seems more probable that it must have been derived from Cretaceous deposits. An even more remarkable occurrence is the dis- covery of many specimens of Terebratula liarlani under similar condE tions (see p. 204). Occurrence. — Aquia Eoemation. Clifton Beach. Collection. — Maryland Geological Survey. Family PTERIIDAE. Genus PTERIA Scapoli. Pteria limula (Conrad). Plate LI, Fig. 1. Avicula limula Conrad, 1833, Fossil Shells of the Tertiary, No. 4, p. 39. Description . — Shell convex, with slight concentric undulations; umbo tapering gradually towards the apex, which is acute, but not prominent; wings large and very oblique; sinus of the posterior margin not profound; nacre very pearly and iridescent. Height, inches.’^ Conrad, 1833. Height of largest fragment, 18 mm. Occurrence . — Hanjemoy Formation. Popes Creek, Hills Bridge. Aquia Formation. Upper Marlboro. Collection. — Maryland Geological Survey. Family ARCIDAE. Genus GLYCYMERIS Da Costa. Glycymeris idoneus (Conrad). Plate LI, Figs. 2, 2a, 3, 3a, 4. Pectunciilas idoneus Conrad, 1833, Fossil Shells of the Tertiary, No. 4, p. 39. Pectanculus idoneus Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Peciunculus idoneus Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 84, pi. xxix, figs, la-lc, 2. Description . — Shell suborbicular, thick, convex; oblique, with rather obscure radiating striae, and very minute, intervening lines; umbo con- vex; beaks distant, rather prominent and pointed; cardinal teeth large; MARYLAND GEOLOGICAL SURVEY 195 truncated in the center by a rectilinear line; cavity capacious; margin crenate. Length, in ” Conrad, 1833. Shell moderately thick, obliquely orbicular, rather ventricose, slightly inequilateral, equivalve, with faint radiations; hinge with few promi- nent teeth; margins crenulated; beaks depressed. The higher beds of the Aquia formation, especially the indurated ledge at Upper Marlboro and at the localities to the northeast, are very rich in shells of Glycymeris. Although in some features they at times show slight variations from G. idoneus of the Gulf, the differences are too slight to warrant specific distinction. Length, 60 mm.; height, 60 mm. Occurrence . — Xanjemoy Formation. 3 miles above Popes Creek, AYoodstock. Aquia Formation. Upper Marlboro, 1 mile west of Hardesty, Potomac Creek, 1 mile northeast of Piscataway, Hardesty, Sheckels Farm near South Eiver, 2 and 3 miles south of South Eiver, Eolph’s Landing. Collections . — Philadelphia Academy of Xatural Sciences, Johns Hop- • kins University, Maryland' Geological Survey. Family LIMOPSIDAE. Genus TRIGONOARCA Conrad. Trigonoarca decisa (Conrad) var. Plate LI, Figs. 5, 5a. Pectunculns decisus Conrad, 1833, Fossil Shells of the Tertiary, p. 39. Limopsis decisus Conrad, 1860, Jour. Acad. Nat. Sci. Phila., 2nd ser., vol. iv, p. 297, pi. xlvii, fig. 13. (?) Noetia pulchra Gahb, 1860, Jour. Acad. Nat. Sci. Phila., 2nd ser., vol. iv, p. 388, pi. Ixvii, fig. 65. Trigonoarca pulchra var. Harris, 1897, Bull. Amer. Pal. No. 9, p. 48, pi. viii, figs. 2, 2a. Description . — Shell longitudinally suhoval, equilateral, with obsolete radiating striae; posterior end obliquely truncated, umbonial slope angu- lated, incurved; beaks small, pointed and recurved; cardinal teeth small and crowded; series not much arcuated; margin entire. Length, J of an inch.^’ Conrad, 1833. This form is smaller and proportionally longer than T. pulchra Gahb 196 SYSTEMATIC PALEONTOLOGY" and has fainter sculpture. It is much more like the variety figured by Harris. Length, 4 mm.; width, 2.5 mm. Occurre7ice. — Nanjemoy" Fokmation. Woodstock. Collection . — Maryland Geological Survey. Family PARALLELODONTIDAE. Genus CUCULLAEA Lamarck. CucuLLAEA GiGANTEA Conrad. Plates LII, LIII, LIV, LV. Cucnllaea qigmitea Conrad, 1830, Jour. Acad. Nat. Sci. Phila., vol. vi, p. 227, pi. x, tig. 4. Cucullaea onochela Roi^ers, 1839, Trans. Amer. Philos. Soc., vol. vi, p, 372, pi. xxviii, fig. 2. Cucullaea transversa Rogers, 1839, Trans. Amer. Philos. Soc., vol. vi, p. 373, pi. xxix, fig, 1. Cucullaea gigantea H. C. Lea, 1848, Proc. Acad. Nat. Sci. Phila., vol. iv, p. 98. Cticullaea onochela H. C. Lea, 1848, Proc. Acad. Nat. Sci. Phila., vol. iv, p. 98. Cucullaea transverm H. C. Lea, 1848, Proc. Acad. Nat. Sci. Phila., vol. iv, p. 98. Cucullaea rogersiana Nyst, 1848, Tabl. Synopt. Arcacees, p. 63. Latiarca gigantea Conrad, 1865, Amer. Jour. Conch., vol. i, p. 11. Latiarca onochela Conrad, 1865, Amer. Jour. Conch., vol, 1, p. 11. Latiarca transversa Conrad, 1865, Amer. Jour. Conch., vol. i, p. 11. Latiarca gigantea Conrad, 1866, Smith. Misc. Coll. (200), p. 4. Latiarca onochela Conrad, 1866, Smith. Misc. Coll. (200), p. 4. Latiarca transversa Conrad, 1866, Smith. Misc. Coll. (200), p. 4. I^atiarca idonea Conrad, 1872, Proc. Acad. Nat. Sci. Phila., p. 53, pi. ii, fig. 1. Area rogersi Heilprin, 1881, Proc. Acad. Nat. Sci. Phila., p, 449. Cucullaea onochela Rogers, 1884, Geology of the Virginias, p. 669, pi. iii, fig. 2. Cucullaea transversa Rogers, 1884, Geology of the Virginias, p. 670, pi. iv, fig. 1. Area onochela Heilprin, 1884, Contrib. Tert. Geol. and Pal., p. 87. Cucullaea transversa Harris, 1894, Amer. Jour. Sci., ser. iii, vol. xlvii, p. 302. Cucullaea gigantea Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Cucullaea gigantea Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 84, pi. xxx, xxxi, xxxii, xxxiii. Cucullaea gigantea var. Harris, 1897, Bull. Amer. Pal. No. 9, p. 49, pi. viii, figs. 3a, 4. Cucullaea gigantea Dali, 1898, Trans. Wagner Free Inst. Sci., vol. iii, pt. iv, p. 603. Cucullaea transversa Dali, 1898, Trans. Wagner Free Inst. Sci., vol. iii, pt. iv, pp. 603, 646. Description . — Shell subtriangular, obliquely cordate; very ventri- cose, with numerous longitudinal sulci; anterior side flattened, produced MARYLAND GEOLOGICAL SURVEY" 197 and snbcnneiform; posterior side very short; umbones gibbous; beaks distant and much incurved.*^ Conrad, 1830. A careful examination of the various forms of Cucullaea from the Maryland and Virginia Eocene shows them to be modifications of a single species that possesses great variability in outline and surface decoration. The most profound changes appear upon comparison of 3 ’oung and adult forms. The immature shells are relatively not as high or as tumid and possess much narrower ligament areas than the adults. Kogers gave the name of C. transversa to these young forms. Casts of tlie larger shells are not uncommon and are locally known as ^Aurtle heads.’^ Professor Harris agrees with us in regarding the Maryland-Yirginia Cucullaeas as all of one species, and also includes in it a form from the Chickasawan of Alabama of the transversa type. Dr. Dali, however, recognizes two species. If it were possible to separate the forms the dis- tinction between the gigantea and transversa types would be very useful, since the former occurs only in the Aquia formation, while the latter is the only form found in the Hanjemoy formation or in the Gulf states. Occurrence. — Xaxjemoy" Formation. Popes Creek, Woodstock, Thrift (well). Aquia Formation. Liverpool Point, 1 mile southeast of Mason Springs, Potomac Creek, Paspotansa Creek, 2 miles below Po- tomac Creek, Aquia Creek, Clifton Beach, 1 mile northeast of Piscata- way. Upper Marlboro, Hardesty, Eolph’s Landing, 3 miles west of Leeland, Fort Washington, Glymont, SheckeFs Farm near South Eiver, Fredericktown (?). Collections . — Maryland Geological Survey, Johns Hopkins University, U. S. Xational Museum, Philadelphia Academy of Hatiiral Sciences. Led A PARVA (Eogers). Plate LVI, Figs. 5, 6, 7, 7a. Xacula parva Rogers, 1837, Trans. Amer. Philos. Soc., vol. v, p. 840. (Reprint Geology of the Virginias, 1884, p. 668.) Xacula parva H. C. Lea, 1848, Proc. Acad. Nat. Sci., Phila., vol. iv, p. 102. Leda parva Conrad, 1854, Proc. Acad. Nat. Sci. Phila., vol. vii, p. 29. Xaculana parva Conrad, 1865, Amer. Jour. Conch., vol. i, p. 3. Xuculana parva Conrad, 1866, Smith. Misc. Coll. (200), p. 3. Lecla parva Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Leda parva Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 83, pi. xxviii, figs. 2a-2d 198 SYSTEMATIC PALEONTOLOGY Description . — Shell ovate, inflated, rounded before, not much pro- duced, but rapidly tapering to a truncated point behind, furnished with about twelve rather coarse concentric folds or ridges, and a longitudinal gently depressed groove or undulation of surface, running from near the beak to the posterior basal margin; beaks nearly central; anterior series of teeth slightly arched; posterior series nearly straight; margin entire; cavity rather deep/^ Kogers, 1837. Length, 5 mm.; height, 3 mm. Occurrence . — Nanjemoy Fokmation. Popes Creek, Woodstock, miles above Popes Creek. Collections . — Philadelphia Academy of Natural Sciences, Johns Hop- kins University, Maryland Geological Survey. Leda cultellieokmis (Rogers). Plate LVI, Figs. 8, 8a. Nucula cultelliformis Rogers, 1837, Trans. Amer. Philos. Soc., new series, vol. v, p. 339. Nucula cultelliformis H. C. Lea, 1848, Proc. Acad. Nat. Sci. Phila., vol. iv, p. 102. Leda cultelliformis Conrad, 1854, Proc. Acad. Nat. Sci. Phila., vol. vii, p. 29. Nuculana cultelliformis Conrad, 1865, Amer. Jour. Conch., vol. i, p. 13. Nuculana cultelliformis Conrad, 1866, Smith. Misc. Coll. (200), p. 3. Nucula cultelliformis Rogers, 1884, Geology of the Virginias, p. 667. Yoldia cultelliformis Clark,. 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Leda {Adrana) cultelliformis Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 83, pl_ xxviii, ligs. 3a, 35. Description . — Shell ovate, ensifgrm, somewhat inflated, rounded be- fore, much elongated and tapering behind, the posterior length more than twice the anterior, furnished with very fine, hardly distinct concen- tric striae, and one distinct and one very obscure rib behind; anterior part with an indistinct fold; shell thin; lunule long and lanceolate; beak small; anterior series of the teeth gently arched; posterior series straight; teeth in both acutely bent, the angles directed toward the beak; margin entire; cavity of shell shallow, with a ridge passing from the beak to the posterior margin.^^ Rogers, 1837. Length, 10 mm.; height, 4 mm. Occurrence . — Aquia Formation. Clifton Beach. Nanjemoy' For- MAKYLAXD GEOLOGICAL SURVEY 199 MATiox. Popes Creek, miles above Popes Creek, Woodstock, Upper Marlboro (deep cut near Chesapeake Beach E. R. station). Collections . — Johns Hopkins University, Maryland Geological Survey. Family LEDIDAE. Genus LEDA Schumacher. Led A IMPROCERA (Conrad). Plate LVI, Figs. 1, 2, 3, 4. Nucula improcera Conrad, 1848, Jour. Acad. Nat. Sci. Phila., 2nd ser., vol. i, p. 131, pi. xiv, fiff. 23. Nuculana improcera Conrad, 1865, Amer. Jour. Conch., vol. i, p. 13. Nxiculana improcera Conrad, 1866, Smith. Misc. Coll. (200), p. 3. Leda improcera Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Leda improcera Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 83, pi. xxviii, figs. la-ld (not Ic). Description. — Elongate, very inequilateral, convex, polished, and having fine indistinct concentric lines; anterior side produced, bicarin- ated; the upper margin incurved toward the apex; extremity angulated.” Conrad, 1848. This species shows considerable variation in outline. Conrad’s types are of the more elongate form. If the more elevated form is a con- stant variation it should be separated as a new variety or species. Length, 8 mm.; height, 4 mm. (typical). Length, 11 mm.; height, 7 mm. (elevated form). Occurrence . — Hanjemoy Formation. Popes Creek, Woodstock, Head of Hanjemoy Creek, 2J miles above Popes Creek. Collections . — Johns Hopkins University, Maryland Geological Survey. Leda parilis (Conrad). Plate LVII, Figs. 1, 2, 2a. Nucula parilis Conrad, 1848, Jour. Acad. Nat. Sci. Phila., 2nd ser., vol. i, p. 132, pi. xiv, fig. 31. Nucula parilis Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 93. Description. — Ovate, ventricose, with concentric lines; beaks medial; anterior end pointed, angular; posterior end regularly rounded; an- terior submargin carinated, hinge margin very oblique, straight from 200 SYSTEMATIC PALEONTOLOGY the apex, except near the end where it is somewhat angnlated.” Con- rad, 1848. This very distinct species has been found only in and immediately above the indurated ledge at Upper Marlboro and Sonth River bridge. It is rare in the indurated ledge but abundant in the shell bed imme- diately above it. The type which came from Upper Marlboro is still in the collection of the Philadelphia Academy of Uatnral Sciences. Length, 15 mm.; height, 9 mm. Occurrence. — Aquia Foemation. Upper Marlboro, Sheckel’s Farm near Sonth River. Collections. — Maryland Geological Survey, Philadelphia Academy of Uatnral Sciences. Leda paeilis vae. Plate LVII, Fig. 3. Leda improcera Clark, Bull. 141, U. S. Geol. Survey, pi. xxviii, fig. 1e. This form is a connecting link between L. cliftonensis and L. parilis and might be the descendant of either. It is less globose and has smaller, more nnmerons folds than L. parilis; and is somewhat more elevated than L. cliftonensis with smaller, more closely-set folds. Length, 11 mm.; width, 6.5 mm. Occurrence. — Uanjemoy Foemation. Hills Bridge, Woodstock. Collections. — Maryland Geological Survey, Johns Hopkins University. Leda potomacensis n. sp. Plate LVI, Figs. 9, 10. (.^) Nuculana protexla Conrad, 1865, Amer. Jour. Conch., vol. i, p. 147, pi. xi, fig. 6. (In part.) Leda protexla Clark, 1895, Johns Hopkins Unix. Circ., vol. xv, p. 5. Leda protexta Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 82. Description. — Shell large, transverse, elongate, anterior side round- ed, posterior somewhat longer, attenuated, terminating in an obtuse beak; surface with numerous concentric striations somewhat interfered with on the rostrated portion of the posterior side, where the riblets become more lamellated and wavy and at times even disappear.’^ Clark, 1896. MARYLAND GEOLOGICAL SURVEY 201 Xiicnlana protexta Conrad (1865), which is Leda protexta Harris (189T), includes two forms. The first has been described by Dr. Dali as Leda pliarcida and occurs at Wood's Bluff, Choctaw Corner, and Cave Branch, x\la. The second, which is Leda protexta Clark (1896), is described here, and occurs outside of Maryland at Bell’s Landing, Gregg’s Landing, and Yellow Bluff, Ala. The above localities are all given from material in the collection of the Philadelphia Academy of Yatnral Sciences. Length, 37 mm.; width, 17 mm. Occurrence. — Yaxjemoy Formation. Woodstock, West of Port To- bacco, 1 mile southeast of Piscataway, ^ mile below Chapel Point, Charles Branch between Eosary ville and Upper Marlboro, Popes Creek. Collections. — Johns Hopkins University, Maryland Geological Survey. Leda cliftonensis n. sp. Plate LVI, Fig. 11. Description. — Shell short, ventricose, posteriorly acute, anterior regu- larly rounded. Surface marked with very regular, concentric folds, with narrow, sharply incised interspaces. Length, 11 mm.; height, 5 mm. Occurrence. — Aquia Formation. 2 miles below Potomac Creek, Po- tomac Creek, Aquia Creek, Liverpool Point, Clifton Beach. Collection. — Maryland Geological Survey. Leda tysoni n. sp. Plate LYII, Figs. 4, 4a, 5. Desci'iption. — Shell of moderate size, thin, not extremely inequilateral; beaks large, proximate; anterior end produced, uniformly rounded; pos- terior end broad, uniformly rounded; surface marked by fine, regular closely-set rounded lamellae with narrow interspaces; hinge-line nearly straight with from twelve to fifteen teeth on either side of a subum- bonal chondrophore. This species has some resemblance to the figures of Nucula capsiopsis de Gregorio.'^ Ann. Geol. et Pal., vol. ii, p. 187, pi. xxii, figs. 28, 24. 202 SYSTEMATIC PALEONTOLOGY Length, 12 mm.; height, 6.5 mm. Occurrence . — Nanjemoy Fokmation. Popes Creek, Woodstock, 1 mile southeast of Piscataway, 2J to 3 miles above Popes Creek. Collections . — Maryland Geological Survey, Philadelphia Academy of Natural Sciences. Family NUCULIDAE. Genus NUCULA Lamarck. Nucula ovula Lea. Plate LVII, Fig. 6. Nucula ovula Lea, 1833, Contrib. to GeoL, p. 80, pi. iii, fig. 59. Description . — Shell ovate, oblique, inflated, very inequilateral, trans- versely striate, longitudinally and very minutely ribbed; substance of the shell thin; lunule large, not deeply impressed; beaks pointed, re- curved; anterior series of teeth short, posterior series long; fosset nearly direct; cavity of the shell deep; margin very minutely crenulate; nacre pearly.” Lea, 1833. Length, 11 mm.; height, 7.5 mm. Occurrence . — Aquia Foemation. Tipper Marlboro, Sheckeks Farm near South Eiver. Collection . — Maryland Geological Survey. Nucula potomacensis n. sp. Plate LVII, Figs. 7, 7a, 8, 8a. Nucula magnifica Clark, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Nucula magnifica Clark, 1896, Bull. 141, U. S. Geol. Survey, p. 82. Not Nucula magnifica Conrad. Description . — Shell small, thin, fragile; valves shallow; surface mark- ed by strong radial striae which are stronger toward the periphery, and along which the shell tends to fracture; margin strongly crenulated; lines of growth faint and irregular, other concentric sculpture lacking; interior with a silvery luster; beaks anteriorly situated; lunule indis- tinct; chondrophore narrow, oblique; anterior teeth about fifteen, pos- terior teeth about six. MARYLAND GEOLOGICAL SURVEY 203 Length, 11 mm.; height, 8 mm. Occurrence . — Xanjemoy Formation. Woodstock, Head of Xanjemoy Creek, Charles Branch between Eosaryville and Upper Marlboro, Popes Creek, East and west of Port Tobacco, Tapper Marlboro (deep cut near Chesapeake Beach E. E. station), miles above Popes Creek. Collections . — Maryland Geological Survey, Johns Hopkins University. MOLLUSCOIDEA. Class BRAG H 10 POD A. Order TELEOTREMATA. Family TEREBRATELLIDAE. Genus PLATIDIA Costa. Platidia marylandica n. sp. Plate LYIII, Figs. 1, la, lb, Ic. Description . — Shell small, subcircular, somewhat depressed, with well- marked lines of growth; ventral valve with hinge-area prominent, high, bisected by a large open foramen and with a well-defined, linear septum in the interior; dorsal valve with large pedicle incision, and with a short, high, slightly bifurcated medium septum in the interior; teeth and sockets prominent; shell structure minutely punctate. This beautiful little brachiopod is not uncommon at Upper Marlboro where it is found associated with bryozoans and foraminifera. There is no other American fossil species of this genus. Length, 4 mm.; width. 4 mm. Occurrence . — Aquia Formation. Upper Marlboro. Collection . — Maryland Geological Survey. 204 SYSTEMATIC PALEONTOLOGY Family TEREBRATULIDAE. Genus TEREBRATULA Llhwyd. Tekebratula haelani Morton. Plate LVIII, Figs. 2, 3, 3a. Terebratula harlani Morton, 1829, Jour. Acad. Nat. Sci. Phila., vol. vi, p. 73, pi. hi, tigs. 1-4, 7, 8; Amer. Jour. Sci., vol. xvii, p. 283; vol. xviii, pi. iii, tig. 16 . Terebratula harlani Bao-g, 1898, Amer. Geol., vol. xxii, p. 370. Description . — Shell large, about twice as long as broad, sides straight and imperfectly parallel; upper valve plano-convex, obscnrely bipli- cated except near the margin, which has three inconsiderable sinuses; loAver valve very convex, with a longitudinal ridge and slight lateral depressions; beak incurved; umbo prominent.’^ Morton, 1829. Mr. Schuchert states in a private communication that The Tere- bratula harlani from the Eocene show a tendency to variation which if constant I would use as a distinguishing character for the establishing of a variety. This tendency is for the shell to become a little wider with the loss of lohation. Similar shells also occur among the Cretaceous specimens hut the form seems to he rare. If in the Eocene this form is the prevailing one then it shows the line of variation in evolution. However, if you give these Eocene specimens a varietal name, call atten- tion to the fact that the identification cannot he made from single specimens. Another slight difference is the wide area on each side of the crural processes. This also has no particular value. I should never have be- lieved the finding of Terebratula harlani in Eocene strata had I not seen these specimens with your remarks as to occurrence and associated Eocene fossils.^’ Whether the specimens of Terebratula harlani found associated with typical Eocene fossils are to he regarded as mechanically derived from Cretaceous deposits or are really Eocene representatives of this import- ant species the authors have not been able to determine. A careful study of the many shells found does not afford any evidence that they were transported to any distance although in some instances occurring well above the base of the Eocene. Furthermore, it cannot be definitely MARYLAND GEOLOGICAL SURVEY 205 shown, so far as these occurrences are concerned, that the Eancocas for- mation, to which Terehratula liarlani is limited farther north, really ex- ists or ever did exist in the area below the Eocene strata. The specimens obtained, however, are not unlike the Cretaceous forms. It is important in this connection that they have never been observed in the intervening Manasquan and Shark River formations, both of which have furnished a considerable number of other species. The specimens vary considerably in size, although the larger forms predominate. The largest specimens are from 70 to 80 mm. in height and 10 to 50 mm. in width. Occurrence. — Aquia Formation. 3 miles west of Leeland, Severn River opposite Annapolis. Collections . — Maryland Geological Survey, Maryland Academy of Sciences. Class BRYOZOA. Order CYCLOSTOMATA. Family TUBULIPORIDAE. Genus DISCOSPARSA d’Orbigny. Discosparsa varians n. sp. Plate LIX, Fig. 3. Description . — Zoarium forming subcircular (young) or irregular, un- dulating expansions, 2 to 10 mm. wide, parasitically attached, or more or less free and epithecated beneath. In young colonies which are often spread over the original layer, the zooecial apertures, which are enclosed by moderately elevated, ring-like peristomes, are, sometimes uniserially, but never very regularly, arranged in a radiate manner about the small, depressed and smooth central space. In older examples, there are sev- eral of these maculae, but the radial arrangement of the zooecia about them, is generally obscure. The ooecia immediately surrounding the maculae are often of larger size and more oblique than those covering the intermediate spaces where they are quite direct, but in worn ex- amples very little difference in size is noticeable. The interzooecial 206 SYSTEMATIC PALEONTOLOGY spaces, which are solid and concave normally, are pitted in worn speci- mens as thongh they contained covered mesopores or vesicles. The nn- worn covering is minutely punctate, as are also the covers closing some of the zooecial apertures. The zooecia form mere inflations of the sur- face, usually (perhaps always) over one of the maculae, which in that case is slightly raised instead of depressed and pierced by somewhat scattered apertures. An average of nine zooecia occur in 2 mm. Tube walls as seen in fractured specimens, thin beneath the outer crust, min- utely perforated, the pores arranged in transverse series with nearly three of the rows in the space equalling the width of a tube. No diaphragms were observed. Length of tubes, 1 mm. or less. The Lower Eocene specimens have been identified with a common form in the washings of the Lpper Cretaceous at Yincentown, N. J. In the latter the arrangement of the zooecia is usually more regular and the maculae scarcely so noticeable as they are in the Upper Marlboro specimens, but other Yincentown specimens agree very closely with the one illustrated on Plate LIX, Fig. 3. The generic position of the species ma)^ be considered a trifle doubtful. The wholly parasitic specimens would probably be placed by most authors under Berenicea, but it does not seem that the species in any of its forms is ever truly a Berenicea. Besides, these parasitic specimens cannot possibly be distinguished in other respects from the free laminar and even discoid specimens here united with them. Discosparsa as established by d’Orbigny and ac- cepted by Pergens, includes discoid or cupuliform zoaria, attached by the central portion of the base only. The zooecial apertures are dis- posed irregularly or in intersecting curved lines about the center of the upper surface. As these conditions are fully complied with by at least some of the Yincentown specimens of D. varians, it appears reasonable to place the species under Discosparsa rather than Berenicea. There is no described American species closely resembling D. varians and none of those from European deposits seem near enoiigh to require detailed comparison. The species is common in the Upper Cretaceous at Yincen- town, X. J. Occurrence. — Aqijia Fokmation. Upper Marlboro. Collection. — Maryland Geological Survey. MAKYLAXD GEOLOGICAL SUKVEY 207 Family FASCIPORIDAE. Genus FASCIPORA d’Orbigny. Fascipoea subkamosa n. sp. Plate LIX, Figs. 1, 2. Description . — Zoarium consisting of small flattened branches, varying from snbcylindrical to tlabellate, usually about 1.5 mm. in thickness. Ends of branches convex, occupied by the months of numerous sub- equal, thin-walled, angular tubes, usually about 0.12 mm. in diameter. Sides of branches with rather obscure transverse wrinkles and the aper- tures of the true or fully-developed zooecia. The latter are somewhat scattered, though a tendency to arrangement in series— chiefly longitu- dinal — is commonly apparent. The rounded contour of the zooecial tube-wall is but dimly discernible behind the moderately raised aper- tural rims. Zooecial apertures ovate, about 0.14 mm. by 0.18 mm., with about five in 2 mm. Interapertural space as well as apertural covers, minutely punctate. In vertical fractures the tubes are shown to be very long and that they approach the surface very gradually. Ooecium a mere inflation of the surface through which one or more of the zooecial tubes pass. In the general form of its zoarium this species agrees very well with F. pavonina (Michelin) d’Orbigny’s type of the genus, but its zooecia are much smaller and not nearly so prominent. Occurrence . — Aquia Fokmation. Upper Marlboro. Collection . — Maryland Geological Survey. Family IDMONIIDAE. Genus RETICULIPORA d’Orbigny. Eeticulipoka DlCHOTOiiA Gabb and Horn. Plate LIX, Figs. 9-12. Reticulipora dichoioma Gabb and Horn, 1862, Jour. Acad. Nat. Sci. Phila., 2nd ser., vol. V, p. 178, pi. xxi, lig. 64. Comp. Bicritiina gandryana Pergens, 1890, Revis. des Bryozoaires du Cretace, Bull. Soc. Beige de Geol., t. iii, pi. xiii, tig. 2. Description . — Fragments only of this species have been seen. So far as these admit of judging, the zoarium is not reticulated but consists of 208 SYSTEMATIC PALEOXTOLOGY laterally compressed curved branches, 2 to 3 mm. wide or high and 1 mm. or less thick, throwing oft similar branches from their sides. Oc- casionally they appear to divide dichotomonsly, but this probably is not really the case. The zooecial apertures are subcircular or oval, 0.08 to 0.10 mm. in diameter, arranged in more or less irregular transverse series, five or six in 1 mm., oblique, with the peristome higher behind than in front. Except for an occasianal large cell (? zooecinm) the lower third or half of the branches is without zooecial apertures and in the worn condition may appear quite solid. When in a good state of preservation, however, this part of the surface is covered by angular depressions, of varying sizes, the centers of the depressions usually show- ing the mouth of a small pore. Similar pores extend upward and oc- cupy the depressed spaces between the rows of zooecial apertures. Gon- ocysts of the same type as in Berenicea, Discosparsa and Fascipora. The zooecial tubes pass through them without interruption, but the mesopores do not. Closures of zooecial tubes, some distance below the external orifice, appear to have a central perforation. A species recently described by Pergens (loc. cit) from the Cretaceous (Senonien) of France, under the name of Bicrisina gaudryana, is either the same as R. dichotoma or extremely like it. The species occurs in the Upper Cretaceous at Timber Creek and Yincentown, U. J. Occurrence. Aquia Eokmatiox. Upper Marlboro. Collection . — Maryland Geological Survey. Family CERIOPORIDAE. Genus CAVARIA Hagenow. Cavaria dumosa n. sp. Plate LIX, Figs. 4-8. Description. — Zoarium forming small, bushy masses, consisting of fre- quently and irregularly dividing and coalescing branches, varying in thickness generally from 1.5 to 2.0 mm., but occasionally reaching 3.0 mm. Surface of the most nearly perfect specimens exhibiting at irreg- ular intervals; small, slightly depressed maculae, smooth or occupied solely b}'’ mesopores. In these specimens the zooecia are readily dis' tinguished from the meso})ores by their prominent peristomes and MARYLAND GEOLOGICAL SUEYEY 209 rounded as well as larger apertures. The mesopores occur in the maculae and in the depressed spaces between the zooecia, are something like twice as numerous as the latter, and have small though variable apertures set in the bottoms of rounded or angular depressions. Inner diameter of zooecial apertures about 0.8 mm., with four in the space of 1.0 mm. In young or slightly worn examples the maculae are not readily distinguished, the mesopores relatively larger and the two sets of mouths more nearly alike than in the condition described above. Gonocysts large, appearing as rounded or irregular inflations of the surface perforated by the mouths of zooecial tubes which pass through them without interruption. Beside each zooecium is the orifice of a smaller tube, the nature of which is not understood. When the outer wall of the gonocyst is broken away, the zooecial tubes, together with the small tubes accompanjdng them, are turned in every direction away from the center. Between them the mouths of the mesopores are covered by a perforated pellicle. The axial hollow or tube varies between 0.2 and 0.4 mm. in diameter, is winkled transversely and further constricted at irregular intervals. At the constrictions a thin curved plate is often observable, but that it extends completely across the cavity has not been observed and from the evidence at hand it is at least doubtful that it ever does. The tubes, as seen in fractures, present no evidence of diaphragms, but the con- necting perforations in the walls are quite distinct. They occur mostly in transverse rows, two or three of the rows in a space equalling the width of a tube. Superficially there is considerable resemblance between this species and Heteropora (Multicrescis) parvicella Gabb and Horn, a common fossil of the Upper Cretaceous deposits at Vincentown, X. J. The ramulets of that species, however, are more slender and divide less frequently while its zooecia and mesopores appear more scattered. But the prin- cipal difference lies in the central hollow which is wanting in Gabb and Horn’s species and distinguishes Cavaria from Heteropora. Of the three species of Cavaria described by Hagenow, only C. ramosa, the type of the genus, is at all similar. In this the axial hollow is rela- tively larger and is crossed by strong transverse partitions. The branches 14 210 SYSTEMATIC PALEONTOLOGY also appear to be smaller and the apertures of both zooecia and ineso- pores smaller, more angular and less regularly disposed than in C. ra- mosa. Occurrence. — Aquia Formation. Upper Marlboro (in fragments). Collection . — IMaryland Geological Survey. Genus CERIOPORA Goldfuss. Ceriopora micropora Goldfuss. Plate LIX, Figs. 13, 14. Ceriopora micropora Goldfuss, 1822, Petr, i, p. 33, pi. x, fig. 4c^ (not 4a-c). Ceriopora micropora Hagenow, 1851, Die Bryozoen der MaastricRter Kreide bildiing, p. 52, pi. V, fig. 4. Description . — Among the Survey material received for description is a single zoarium agreeing too closely with C. micropora, as redefined by Ftagenow and represented by several examples in the authoFs private collection received from Dr. Ed. Pergens, to admit of distinguishing it at present. The specimen is depressed globular in shape, nearly 5 mm. in diameter, hollow beneath, and composed of at least three layers of zooecia. The zooecial apertures are not very clearly shown by the speci- men but appear to be a trifle smaller, more unequal and thinner walled than in the Maastricht colonies. Occurrence. Xanjemoy Formation. 2^ miles above Popes Creek. Collectio7i . — Maryland Geological Survey. Genus HETEROPORA Blainville. HeTEROPORA (?) TECTA n. sp. Plate LIX, Figs. 15, 16. Description . — Zoarium consisting of small, subramose masses or stems, 2 or 3 mm. in thickness, the upper ends of which are rounded and cov- ered uniformly with angular thin-walled tube mouths, about seven in 1 mm. A large proportion of the sides of the specimen figured is cov- ered with a thin and minutely punctate pellicle, the tube apertures covered thereby being quite obscured. Most of the apertures showing through or piercing the pellicle, are of rounded form, with an inside diameter of about 0.13 mm., and enclosed by a ring-like peristome. MARYLAND GEOLOGICAL SURVEY 211 Tlicse are regarded as the true zooecia, the other tubes being probably all of the nature of meso})ores. In longitudinal sections the tubes have thin walls, perforated as usual, are developed in any part of the axial region and approach the surface in a very gradual curve. No dia- pbragnis were observed. No Ilcteropora has been seen by the autlior that resembles this spe- cies very closely. Indeed, there is a doubt regarding its belonging to this genus, but, after comparing it with all the described genera of this section of the Cyclostomata, it a])pears to agree better with Heteropora than with any of the other genera. Occurrence. — Aquta Formation. Upper ^larlboro. Collection . — ^faryland Geological Survey. Order CH 1 LO STOMATA. Family MEMBRANIPORIDAE. Genus MEMBRANIPORA Blainville. ^Iembranirora rimulata n. sp. Plate LX, Figs. 1, 2. Description . — Zoarium adnate, forming a thin, single sheet of indefi- nite extent. Zooecia hexagonal in form, arranged quincuncially with the longitudinal rows generally very regular. Apertures occupying the whole of the large opesium, quite regularly ovate in shape. Rim or interapertural space narrower than the oj)esia, rounded, sometimes an- gular in the middle but oftener with a depressed interzooecial suture line, marked vdth close transverse lines or wrinkles. Taking the place of an ordinary zooecium isolated cells or, more commonly, turn or three in longitudinal sequence, occur which dilYer from the rest in having a convex cover with a narrow median slit and above the slit a linear cres- centic impression. These cells may represent an unusual type of ooecia but more probably are to be considered as a form of vicarious avicularia or vibracula. The specimens upon which the species is founded are divisible into two varieties, one with smaller zooecia and opesia and thicker walls 212 SYSTEMATIC PALEONTOLOGY than the other. Measuring longitudinally the former has four and one- half zooecia in 2 min., the other only three and a half. Diagonally one has six, the other five in the same space. Thickness of zooarial sheet not exceeding 0.2 mm. Membranipora perampla Gabb and Horn, which occurs rather fre- quently in the Upper Cretaceous at Vincentown and other points in Hew Jersey, sometimes resembles this species, but its zooecia are larger, less regular, with irregular spaces often between the rims and one side of the latter generally higher than the other, while none of the covered cells described above have so far been observed in it. The zooecia are more regularly arranged in M. rimulata than in any of the simple spe- cies of the genus known to the writer, and this fact, together with the presence of the peculiar covered cells, is principally relied upon in dis- tinguishing the species. Two fragments in my collection of Cretaceous bryozoa found at Vincentown, H. J., and regarded as Biflustra disjuncta Gabb and Horn, have very similar covered cells, and, considering the variations shown in my specimens of this species, seem to show a closer relation to M. rimulata than to any other form. Occurrence. — Aquia Formation. Upper Marlboro. Collection. — Maryland Geological Survey. Membranipora spiculosa n. sp. Plate LX, Figs. 3, 4. Description. — Zoarium adnate. Zooecia arranged in quincunx or ir- regularly, oblong, rounded and widest above, more or less produced be- low. Opesia large, normally ovate, the upper edge nicely rounded, the lower variable, taking up about half of the length of the zooecium. Eim thin, highest above, usually dying out before reaching lower ex- tremity of zooecium. Front wall over lower half of zooecium, slightly depressed, covered with small granules or spines, those bordering the edge projecting sharply into the opesial opening. Ooecia numerous, cucullate, strongly elevated, often with a tubercle or point forming the summit. When a zooecium is without an ooecium its place is often oc- cupied by an elevated avicularium of moderate size. The avicularia are very few in number but when present similar to those found in Repto- MARYLAND GEOLOGICAL SURVEY 213 flustrella lieteropora Gabb and Horn. Length of zooecinm 0.5 or 0.6 innu; width 0.25 to 0.30 inin. The specimen described shows a single cell differing from the rest in being closed, a convex cover, at the upper extremity of which a semi-circular impression is distinguishable, extend- ing over the whole. Occurrence. — Aquia Formation. Upper Marlboro. Collection . — Maryland Geological Survey. Membranipora angusta n. sp. Plate LX, Figs. 5, 6. Description. — Among the material from Upper Marlboro, there are several specimens of a delicate Membranipora that, on account of their imperfection and fragile nature, it may be risky to distinguish as a new species. However, as it is easily recognized and may prove useful in stratigrajihic studies the writer has ventured to name it as above. The zooecia are shallow, elongate, elliptical, hexagonal or rhomboidal and separated exce^it in young stages by a thin tuberculated wall common to adjoining cells (i. e. there is usually no depressed dividing line between the zooecia). The inner portion of the wall is much thicker than the outer, so that the mouths of the connecting pores, of which there are at least six on each side and one or two at each end, are clearly shown in a xiew of the front. Two specimens have cucullate ooecia as shown in Figure 5, and on all an occasional small oval or rounded and slightly raised avicularium may be noticed. The zooecia are about 0.4 mm. long and 0.2 mm. wide. M. angusta apparently belongs to the M. lineata group of AVaters. Occurrence. — Aquia Formation. Upper Marlboro. Collection. — Maryland Geological Survey. Genus REPTOFLUSTRELLA d’Orbigny. Eeptoflustrella heteropora Gabb and Horn. Plate LX, Figs. 8, 9. Jieptojlnstrella heteropora Gabb and Horn, 1862, Jour. Acad. Nat. Sci. Phila., 2nd ser., vol. V, p. 162, j)!. xx, fig. 50. Description . — “ Colony encrusting in irregular patches. Cellules in a single layer, placed with but little regularity, but with a tendency to 214 SYSTEMATIC PALEONTOLOGY radiating lines; elongate, acuminate anteriorly, broadly truncate behind. Opening snbtriangular, with the sides convex, often approaching an oval in very long cellules. Surface regularly convex, bordered anteriorly and laterally by a slightly elevated, rounded edge, usually becoming obsolete as it approaches the proximal end of the cellule. Special pore placed in advance of the opening, small and round. No ovarian vesicles were observed. Old cellules are closed over by a continuation of the surface wall totally obliterating the aperture. In this case the ^ special pore ’ is also generally obliterated, merely showing a slight depression.^^ Gabb and Horn, 1862. The Eocene specimens are coarser in appearance than the Cretaceous form of the species, of which the writer has a number of excellent examples. They differ further in the more pronounced character of the granulation of the front wall and opesial margin, the Cretaceous form being almost smooth; in more frequently assuming a rhomboidal form of zooecium; and in the relatively smaller size of the opesium and larger avicularia. Cucullate ooecia, less prominent but otherwise similar to those of Membranipora spiculosa, occur not infrequently upon the Cre- taceous specimens but are wanting on the Eocene material in hand. When these occur they take the place of the avicularium which other- wise occurs invariably on, or, just above, the upper rim of the zooecium. The species occurs in the Cretaceous at Mullica Hill, Timber Creek, and Ahncentown, N. J. Memhra7iipora spiculosa is a closely related species, but has a more ovate and larger opesium and differently shaped zooecia. Occurrence. — Aquia Eokmation. Upper Marlboro. Collection. — Maryland Geological Survey. Genus BIFLUSTRA d’Orbigny. Biflustra torta Gabb and Horn. Plate LX, Eig. 7. Biflustra torta Gabb and Horn, 1862, Jour. Acad. Nat. Sci. Phila., 2nd ser., vol. v, p. 152, pi. XX, tig. 36. Description . — Colony composed of very compressed branches, usu- ally twisted, rarely in the same plane for more than a quarter of an MAKYLAXD GEOLOGICAL SURVEY 215 inch. Cellules arranged in longitudinal lines and usually in quincunx. About six to ten rows on each side of the branches, although we have in one case counted twenty just below a bifurcation. Cellules closely jux- taposed; elongated oval anteriorly, contracted and afterwards dilated posteriorly, and straight or slightly emarginate at the proximal edge. Opening elongated oval, variable in form and size, occasionally sub- quadrate, sometimes slightly narrowed posteriorly, either more or less than half the surface of the cellule, no lip or margin, simply pierced in the substance of the cellular wall and placed at the lowest part of the surface. Surface smooth, concave, elevated at the anterior and antero- lateral margins into a rounded or acute edge, a little higher than the posterior of the surface of the adjoining cellules. From this edge the surface slopes inwards toward the mouth. Behind the mouth the sur- face is generally marked by two radiating depressed lines, running from the proximal corners of the mouth to the corresponding corners of the cellule, between which is a rounded elevation, not as high, however, as the anterior end of the preceding cellule. The accessory cells [vicarious avicularia] appear to be ordinary cellules undeveloped, and are not always placed immediately in advance of an ordinary cellule. They are about two-thirds of the ordinary size, not closed above, by a testaceous covering, but have the anterior edge very much produced, thin and overhanging, and about as high as the length of the aperture. We have noticed but one broken ovarian vesicle, which is placed in advance of the cellule to which it belongs, appears to have been semiglobular and overlaps the proximal surface of the succeeding cellule, reaching to the edge of the aperture.^^ Gabb and Horn, 1862. Although rather variable this is still to be counted as an easily recog- nized species. Ooecia occur but rarel}q only four or five specimens out of fifty or more in my collection having any at all. They are cucullate, often with a delicate longitudinal ridge across them and about as large as in Membranipora spiculosa, but more uniformly convex. The species occurs in the Upper Cretaceous at Mullica Hill, Timber Creek, and Vincentown, X. J. Occurrence. — Aquia Formatiox. Upper Marlboro. Collection . — Maryland Geological Survey. 216 SYSTEMATIC PALEONTOLOGY EsCHAKA (??) DIGITATA Moi’ton." Plate LX, Figs. 10, 11. Eschara digitata Morton, 1834, Syn. Org. Rem. Cretaceous Group, p. 79, pi, xiir, fig. 8. Eschara digitata Lonsdale, 184.5, Quart. Jour, Geol. Soc. London, vol. i, p, 73, figs, c, d, g^ {a and h?) exclus. e and /. Eschara digitata d’Orbigny, 1850, Prod. Pal. Strat., vol. ii, p. 264. Eschara digitata Gabb and Horn, 1862, Jour. Acad. Nat. Sci. Pbila., 2nd ser., vol. V, p. 114. Description . — Zoarium bifoliate, branching dichotomonsly ; branches flattened, acutely elliptical in cross-section, nsnally 2.5 to 3.0 mm. wide. Zooecia hexagonal, regularly arranged in qnincnnx, about 0.55 mm. long and 0.38 wide, bounded by a slightly impressed line; surface concave, esiiecially toward the aperture which is situated usually just in front of the center. Aperture semielliptical, rounded in front, straight behind, 0.10 to 0.12 mm. wide. Xormally developed and perfect, the posterior border of the aperture is slightly raised and bears a delicate lunarium- like curved plate which extends into the aperture. Abortive cells, pos- sibly of the nature of vicarious avicularia, are frequent but seem to be entirely restricted to the edges of the zoarium and to those portions lying just beneath the axes of bifurcation. They are distinguished from the other cells by their subcircular and usually much smaller apertures. Ooecia unknown. The species occurs abundantly in the Upper Creta- ceous at Mullica Hill, Timber Creek, and Vincentown, X. J. Occurrence. — Aquia Formation. Upper Marlboro (rare). Collection . — Maryland Geological Survey. 1 Of course this species does not belong to the genus Eschara as now understood. Like Bijltistra torta it belongs near or to the genus Onychocella Jullian, Avhich is variously regarded, by some as a mere section of Membranipora., by others as a distinct genus or even as the type of a new family, while Gregory makes it a member of the Mxcroporidae. At present I regard Onxjchocella, taking such a form as Memhranipora augulosa Reuss, as a typical species, as clearly entitled to generic rank and as probably representing a distinct family. It would, however, to say the least, be premature to place either Bijlustra torta or Eschara digitata under Omjchocella^ since neither accords strictly with the more typical species of the proposed genus. When raised to the rank of a family it is highly probable that other generic groups will be established into which these species would fall more naturally than into Onychocella proper. Careful Mr. Waters has already instituted a second genus of the Onychocella type — Vihracella — for Flustrellaria trapezoidea Reuss, while it may yet become desirable to employ some of the names proposed by d’Orbigny for related types. Under these circumstances I prefer leaving the species where Gabb and Horn placed them. MAETLAXD GEOLOGICAL SURVEY 21T Genus LUNULITES Lamarck. Luxulites reversa n. sp. Plate LX, Figs. 19, 20. Description . — Zoariiim flabellate (perhaps originally discoid or de- pressed conical), zooecia snhqnadrate or pentagonal, nsnally widest in the anterior half, arranged in rather irregular radiating lines, about six in 2 mm., with an impressed line separating the rows; area depressed, its sur- face grano-lineate. Margin strongly raised, thick, and straight or slightly concave across the posterior end and much thinner along the sides, the anterior end appearing to be overlapped by the posterior ridge of the next succeeding zooecinm. Aperture surrounded by a thickened rim, generally rounded in front and straighter behind, sometimes sub- quadrate, its anterior border close to the prominent end of the next cell, and the length and width averaging about half the corresponding dimen- sions of the entire zooecinm. Vibracular cells fusiform or elongate oval, rather large, one, usually at each angle of junction between four zooecia. A constriction occurs near the center of each, sometimes on one side only, at other times on both. A narrow area may surround the opening. Under surface marked by irregular depressed lines radiating from the narrow lower extremity of the zoarium. Between these lines the surface is convex and rather coarsely pitted and granulate. The only specimen seen is too imperfect to permit a positive declara- tion that it is not a mere fragment of a discoid zoarium. Still, the arrangement of the depressed lines on the lower surface does not look right for a species in which the zooecia radiate from a center as in the ordinary forms of Lunulites. On the other hand this side looks de- cidedly like d’Orbigny^s figure of his Pavolunulites elegans (Pal. Franc., vol. V, pi. dccvi, fig. 7), hence I expect to find that perfect specimens of L. reversa have a fiabellate and not a discoid or conical form. Specifically, L. reversa is distinguished from all species of Lunulites known to the writer, except L. regularis d’Orbigny, L. semilunaris Marsson and L. patelliformis Marsson, in having the posterior margin of the zooecinm thicker and more premoinent than the anterior. From the species mentioned it differs in the greater elevation and square out- 218 SYSTEMATIC PALEONTOLOGY line of the raised margin, in the larger size and different form of the aperture, and the grano-lineate marking of the whole surface. Occurrence . — Aquia Foemation. 2 miles below Potomac Creek. Collection. — Mar}dand Geological Survey. 'Family CRIBRILINIDAE. Genus CRIBRILINA Hincks. Cribeilina modesta n. sp. Plate LX, Figs. 12, 13. Description . — Zoarinm forming a delicate parasitic patch upon foreign bodies. Zooecia ovate, not very regularly arranged, about 0.4 mm. in length and 0.28 mm. wide, bordered by a thin rim. Front wall gently convex, usually with six (five to seven) radiating and transverse furrows, each with two or three pores, on each side, and a central, flattened, ovate or triangular space, including five or six similar pores placed in obscure transverse furrows. Apertures rounded, prominent, oblique, the pos- terior edge highest and often thickened in its central portion. Small avicularian cells occur near or attached to one part or another of the apertural rim of most zooecia, generally one to each, rarely two. Where three zooecia join there is usually a small open space (? vibracular cell). Ooecia cucullate, moderately arched. I could find none among the numerous species of Crihrilina and the related, if not congeneric, forms referred to E scliaripora, Semiescliari- pora and Reptescliaripora by d’Orhigny that exactly matches the fossil above described. It is distinguished from nearly all of them by the crihrose, central space on the front wall, and the prominent rounded aperture. Occurrence . — Aquia Formation. Upper Marlboro. Collection . — Maryland Geological Survey. Cribeilina crassula n. sp. Plate LX, Fig. 14. Description . — Zoarium encrusting. Zooecia oblong quadrate or hexa- gonal, irregularly arranged, with a heavy, strongly elevated margin, MARYLAND GEOLOGICAL SURVEY^ 219 clithridate in outline. Front wall with a narrow raised ridge running down its center, and five or six transverse and radiating rows of minute punctures lying in furrows. Apertures rounded or subovate, the outline often less curved on the posterior side than elsewhere. Avicularian cells small, raised, variously distriljuted, sometimes one or two and even three to a zooecium; or a cell may have none at all. Ooecia unknown. Zooecia 0.5 to 0.6 mm. in length, 0.25 to 0.30 mm. wide; about seven in 4 mm. measuring lengthwise. The thick marginal rim of the zooecia and the unusual depression of the front wall are regarded as the distinctive characters. The latter feature seems to occur also in Escharipora immersa Gabb and Horn, a species described but unfortunately not figured in their monograph, and founded on a specimen from the Cretaceous at Timber Creek, X. J. Their description leaves much in doubt, but as it is stated that the zoarium forms broad, tortuous and anastomosing plates, celluliferous on both faces, and that the zooecia are arranged in regular quincunx, it seems highly improbable that C. crassula can be the same species. Of other Cribrilmidae known to the writer only Escharipora incrassata d^Orbigny, from the Cretaceous of France, presents considerable resem- blance. That species, however, grows into bifoliate expansions, has larger and relatively longer zooecia and large accessory cells ( ? vicarious avicularia) not observed in (7. crassula. Occurrence. — Aquia Formation. Upper Marlboro. Collection. — Maryland Geological Survey. Family ESCHARIDAE. Genus LEPRALIA Johnston. Lepralia subplana n. sp. Plate LIX, Ehgs. 17, 18. Description. — Zoarium, as seen in three specimens, forming a hollow cylinder, composed of numerous la}^ers, each 0.3 to 0.35 mm. in thick- ness, and varying in diameter according to the number of layers from 7.0 to 13.0 mm. Zooecia not very regularly arranged, sometimes subo- vate, at other times hexagonal or sul)quadrate, longer than wide, the length averaging about 0.45 mm. Upper surface nearly flat, the outline 220 SYSTEMATIC PALEONTOLOGY of the zooecia^ in aged conditions especially, scarcely distinguishable and mainly by a double row of pores which, as shown by fractures, are the mouths of small tubes traversing the walls in a vertical direction. Front wall slightly convex, perforated, the pores usually smaller than those outlining the zooecia, distinctly visible on the inner surface, sometimes wanting over a varying space just behind the aperture. The latter is rounded in front, nearly straight behind, with the angles rounded, gen- erally semielliptical, the width and length averaging, respectively, 0.15 and 0.13 mm. Small, round or oval avicularia generally present. Their position is variable though usually close to the rim of the aperture. While an occasional zooecium may occur, having no avicularia, as many or more will be found having one on each side of the aperture. Ooecia unknown. Fractures dividing the zooecia vertically (see Fig. 18) show that the walls (side and front) are traversed by minute, wavy, vertical tubuli and that the zooecial cavities are connected by two series of pores, the larger set near the bottom and a row of smaller pores above the midhight. The openings of the larger set are often irregularly distributed over the concave floors of the zooecia. A fine specimen from the Cretaceous at Vincentown, N. J., is of a species closely related to L. suhplana but distinguished by several readily apparent differences. In it the young zooecia are more convex than in L. subplana, and the convex portion entirely without perforations. With age, however, the surface becomes distinctly pitted. The vibracula also are more regularly and numerously developed, most zooecia having one on each side of the aperture. The Vincentown specimens may belong to Gabb and Horn’s Reptocdleporaria aspera but certain discrepancies between it and their description and figure render a positive identifi- cation impossible at present. Occurrence . — Aquia Formation. Upper Marlboro. Collection. — Maryland Geological Survey. Lepralia labiosa n. sp. Plate LX, Figs. 15, 16. Description. — Zoarium forming thin crusts over shells and other for- eign bodies. Zooecia rhomboidal, hexagonal or subovate, arranged more MARYLAND GEOLOGICAL SUEVEA" 221 or less irregularly in curved series, five or six in 2 mm. often separated by a depressed line. Front wall punctate, slightly convex, fiat, or de- pressed, the last when the margin on one or both sides is thickened and elevated. x\perture subquadrate or semielliptical, sometimes contracted near the middle, always enclosed by a more or less strongly thickened rim. Avicularia occur on the raised apertural border, usually one to each zooecium, or two, as shown in the figures on Plate LXI. Ooecia unknown. Occurrence . — Aquia Formation. Upper Marlboro. Collection . — Maryland Geological Survey. Genus MUCRONELLA Hincks. Mucronella aspera n. sp. Plate LX, Figs. 17, 18. Description . — Zoarium incrusting, consisting of one or more layers; surface under a low power of magnification presenting a decidedly rough aspect. Zooecia varying from ovate-hexagonal, to sub-rhomboidal, indistinct externally, arranged more or less irregularly, though the rows are more regular than they may appear at first sight; about six in 2 mm. Apertures rounded or subquadrate, 0.13 mm. in diameter, ren- dered oblique by the elevation of the more or less strongly swollen pos- terior margin and the depression of the anterior part. The central por- tion of the raised lip forms a mucro of greater or less thickness and prominence, the same hiding a minute central tooth beneath it, and forming with the rest of the thickened portion of the lip, a more or less obscure resemblance to the figure M. Behind the lip the surface slopes rapidly and in the most nearly perfect example is granulose. In the depressed space in front of the aperture there are, normally, three small raised avicularia (? vibracula) while a few larger avicularia, dif- fering further from the others in being divided into two unequal parts by a cross-bar, ar^ scattered without order among the zooecia. Ooecia are not often seen. When present, they occupy the depressed space in front of the aperture, are cucullate, about as large as the zooecial aperture, and usually bear a furrow running from the summit to the concave edge. 222 SYSTEMATIC PALEONTOLOGY" While the. appearance presented by the surface of the zoarinm is sub- ject to considerable variability^ the essential characters are nevertheless very constant. Compared with the numerous described species possess- ing a mucronate aperture, none seems to be nearer than the form described by Gabb and Horn under the name Escliarifora typica. How- ever, aside from the obvious zoarial differences between the two species, that one being erect and bifoliate, the surface characters of the zooecia are sufficiently different to obviate all necessity for detailed comparisons. Any one familiar with the fossils can scarcely fail to distinguish them at a glance. The species occurs in the Cretaceous at Yincentown, H. J. Occurrence . — A quia Fokmation. Upper Marlboro. Collection . — Maryland Geological Survey. COELENTERATA. Class ANTHOZOA. Order HEXACORALLA. Family TURBINOLIDAE. Genus FLABELLUM Lesson. Flabellum sp. Plate LXI, Figs. 3, 3a. Flabellum sp. V"aughan, 1900, Mon. U. S. Geol. Survey, No. 39, p. 66. Description . — Corallum compressed cuneiform, attached by a short pedicel, with slightly developed marginal wings above the pedicel. The dimensions of the two largest specimens, whose outer surface is unfortu- nately so very much corroded that its detail is destroyed, are: 1 2 mm. mm. Greater diameter of calice 14 13 Lesser diameter of calice L 9 7 Height of corallum 15 15 “ Distinct costae correspond to the larger septa. The number of the septa was not determined with certainty, but is about forty. This may be a new species, but has a suggestive resemblance to some MARYLAND GEOLOGICAL SURVEY 223 varieties of F. cuneiforme, and especially to the older varieties of that species.'^ Yanghan, 1900. Since the above was published Professor Clark has sent me three more specimens of this same species, bnt the material is not yet sufficient to determine whether the species is new or only a varietal form of some species of the genus found further south. The best specimen is rep- resented by Plate LXI, Figs. 1, 2. The dimensions of this specimen are: greater diameter of calice, 15.5 mm.; lesser diameter of calice, 8 mm.; height of corallum, P2.5 mm. This specimen is not so elongate as the two specimens whose measurements are given above, but there is sufficient material to show that they represent only a single species. It possesses nineteen large septa that reach the columella; in each of eighteen of the loculi between these large septa are three septa, one longer with a shorter on each side. In one loculus there is a solitary short septum. Comparison may be made with Flabellum cuneiforme var. pacliypliyllum Gabb and Horn, Flabellum cuneiforme var. wailesi Conrad, and Flabel- lum jolinsojii Vaughan. From the first it differs by its epitheca being not so dense, and the corallum is not so solid, the corallum is more fragile; the second is coarser and larger; F. jolinsoni is not so compressed, the measurements of its calice are: greater diameter about 11 mm., lesser, about 10 mm. or slightly greater. The specimens from Virginia and Maryland are probably nearest to F. jolmsoni. Its horizon is the Woods Bluff beds of Alabama. Occurrence. — Xan.jemoy’ Formation. Woodstock (three specimens). Aquia Formation. x\quia Creek (six specimens), 1 mile southeast of Piscataway (two specimens, including the one figured). Collection. — Maryland Geological Survey. Family TURBINOLIDAE Milne-Edwards and Haime. Genus TURBINOLIA Lamarck. Turbinolia acuticostata Vaughan. Plate LXI, Figs. 4, 4a, 4b. Turbinolia acuticostata Vaughan, 1895, Johns Hopkins Univ, Circ., vol. xv, p. 6. Turbinolia acuticostata Vaughan, 1896, Bull. No. 141, U. S. Geol. Survey, p. 89. Turbinolia acuticostata Vaughan, 1900, Mon. U. S. Geol. Survey, No. 39, p. 89, pi. vi, figs. 13-136. 224 SYSTEMATIC PALEONTOLOGY Description. — Conical in shape, as is nsnal in the genns. Size small. Costae tall and thin with crenate margins. Beginning with 6, 6 more costae are soon developed, making 12, between which in the intercostal furrows are double rows of perforations. The 12-costal condition exists for about 1.5 mm. from the base, when 12 more costae are introduced. The costae on the basal portion of the corallum are very slightly larger than they are on the upper portion; they are not so prominent on the basal portion as in Turbinolia pharetra. In the extreme upper portion 24 rudimentary costae are introduced, making the total number 48, twice as many costae as septa. In the intercostal furrows, after the de- velopment of the rudimentary costae, there are only single rows of per- forations; during the 24-costal stage there are double rows of alternating perforations in the intercostal furrows. The septa are 24 in number, in three cycles. Those of third cycle fuse, about half-way between the corallum wall and the columella, by their margins to the sides of those of the first cycle. The septal faces are beset with distinct, sharp, small spines. All of the septa except those of the first cycle are thin and weak. Columella weak, terminated by a small hexagonal star. Height, 6.5 mm.; diameter of calice, 3 mm.’^ Vaughan, 1900. Since the original diagnoses of this species and T. wautuhbeensis ^ were prepared additional specimens have come to notice, making a revision of the critical remarks on these species necessary. The speci- men of T. acuticostata from Popes Creek possesses a weak columella, with a stellate upper termination. Additional specimens of T. wautub- beensis collected by Mr. Frank Burns at Wautuhhee, Mississippi, show that that species possesses costae with crenate margins. The costae of the original type of T. wautubbeensis are probably worn. These facts have shown that these two species are so closely related that it seemed that it might he necessary to unite them, however, there are still important differential characters. The costal crenations of T. acuti- costata are coarser than those of T. wautubbeensis, and the incisions between the crenations in the former species are deeper than in the latter. The columella in well-preserved specimens of T. wautubbeensis is stouter than in T. acuticostata, but there is not sufficient good ma- 1 Mon. U. S. Geol. Survey, No, 39, p. 88, pi. vi, figs. 11-12, MAEYLAKD GEOLOGICAL SUKTEIT 225 terial to determine the value of this feature. T. wautuhbeensis is the more robust species, T. acuiicostata is more slender. The last men- tioned difference is the most striking one. It is extremely probable that T. wautnhbeensis is a direct descendant from T. acuiicostata. T. yliaretra Lea also possesses a columella with a hexagonal upper ter- mination. It does not possess rudimentary costae, and the costae have entire edges, hut it and the two above discussed species are very closely related and probably should he grouped in a section or subgenus of Turhinolia. Occurrence. — ^N'axjemoy Formation. Popes Creek. Aquia Forma- tion. Potomac Creek. Collections. — Johns Hopkins University, Maryland Geological Survey. Family CARYOPHYLLIDAE. Genus TROCHOCYATHUS Milne-Edwards and Haime. Trochocyathus CLARKE anus Vaughau. Plate LXI, Figs. 5, 5a, 6, 7, 8. Paracyathufi {?) clarkeanus Vaughan, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 6. Paracyathns {?) clarkeanus Vaughan, 1896, Bull. No. 141, U. S. Geol. Survey, p. 89. Trochocyathus clarkeanus Vaughan, 1900, Mon. U. S. Geol. Survey, No. 39, p. 100, pi. vii, flgs. 20-23. Description . — ‘^‘^Corallum conical, usually slightly curved. Cross-section elliptical. Nearly ahvays showing a distinct area of attachment, which is variable in size. Costae not very prominent; acute; 48 in number, corresponding to all the cycles of the septa; nearly equal in size. In young specimens those corresponding to the last cycle of septa are smaller than those earlier developed. No epitheca M'as observed and is most probably absent. Septa thin, not exsert, sides granulated; 48 in number, arranged in six systems of four cycles each; those of the first three cycles reach the columella; the fourth cycle fuse by their inner margins to the sides of the third cycle. Calicular fossa shallow. Pali apparently before all of the cycles of the septa except the last, small and thin, and appear to be arranged in tivo crowns. Eudimentary dis- sepiments apparently present. Columella fascicular; upper surface papillate.” Vaughan, 1900. 15 SYSTEMATIC PALEONTOLOGY 22 () The measurements of the two specimens are: 1 2 mm. mm. Greater diameter of calice 7 7.75 Lesser diameter of calice 6 5.c Height of corallum 12.5 9.75 The specimens on which this species is founded are all imperfect. I could not obtain accurate details concerning the characters of the col- umella or of the pali, but the species seems to present all the essential characters of Trochocyatlius and is therefore referred to that genus. There is no other species of coral with which it could be confused; therefore critical notes are unnecessary. Occurrence . — Aquia Formation. Potomac Creek, Aquia Creek, 1 mile northeast of Piscataway, Marlboro Point. Collections . — Johns Hopkins University, U. S. National Museum, Maryland Geological Survey. Genus PARACYATHUS Milne-Edwards and Haime. Paracyathus marylandicus n. sp. Plate LXI, Figs. 9, 9a,* 9b. Description . — Corallum low, subcylindrical, attached by a wide and somewhat expanded base. Dimensions: greater diameter of calice, 5.75 mm.; lesser diameter of calice, 5 mm.; height of corallum, 5 mm.; great- est width of base, 6.5 mm. Outer surface of corallum glossy, apparently epitheca is present. Cos- tae corresponding to all septa, low, alternately larger and smaller in size near the calicnlar margin, but equal near the base, densely granu- lated and slightly crested along the summit. Granulations also present between the costae. Upper septal margins very slightly exsert. Septa crowded, thin, in four complete cycles; the six primaries slightly the largest and somewhat more prominent; the secondaries slightly smaller than the primaries; the quaternaries are the smallest and the least prom- inent. The septal faces, beset with small, low, conical granules. Septal margins entire, sometimes transversely undulate. Pali present before all except the last cycle of septa and arranged with diagrammatic regu- MAEYLAXD GEOLOGICAL SURVEY 227 larity. Those before the septa of the first cycle are small, and stand not very high above the papillae of the columella; those before the mem- bers of the second are wide and thin; those before the members of the third cycle are very wide and thin, they extend fnlly one-half the dis- tance from the outer limit of the colnmella to the wall. The pali be- fore the septa of the second and third cycles arched upward, their sides are granulated in a measure similar to the sides of the septa, their margins are entire • and transversely nndnlate. The calicnlar fossa is deep, the bottom is gently concave. The upper surface of the colnm- ella consists of nnmerons papillae. There are from the Eocene of the Gulf states two species with which this species should be compared. The first is Paracyathus granulosus Vanghan from Woods Bluff, Alabama. The septa of the first and second cycles in P. gra^iulosus are much stouter and have much more prominent margins than in P. marylandicus. The costae of P. granulosus are thicker and are more prominent than in P. mary- landicus. The latter difference will be made clear by comparing the figures of the latter species given here with the original figures ' of the former. The other is Paracyathus alternatus Vaughan, from the Lower Claiborne of Louisiana, Mississippi and Texas. It exhibits many points of difference. Its costae and septa are thicker and very much more prominent. The pali are also different. They are stouter and fre- quently are bilobedb P. marylaaidicus is strikingly different from any other of our Eocene species of Paracyathus. Occurrence. — Aquia Formation. 1 mile northeast of Piscataway. Collection . — Maryland Geological Survey. Genus BALANOPHYLLIA Searles-Wooci. Balaxopiiyllia desmophyllum Milne-Edwards and Haime. Plate LXI, Figs. 10, 11. Balanophrjllia desmophyllum Milne-Edwards and Ilaime, 1848, Mon. des Eupsam- mides, Annales sci. nat., 3d ser., vol, x, p. 86. 1 Mon. U. S. Geol. Survey, No. 39, pi. viii, fig. 15a. 2 Op. sup. cit., pi. viii, fig. 11a. 228 SYSTEMATIC PALEONTOLOGY BalanophyUia desmophyllum Milue-Edwards and Haime, 1850, Mou. Brit. Fossil Corals. Palaeontogr. Soc., pp. 85, 30, pi. vi, figs. 1 and \a-lc. BalanophyUia desmophyllum Milne-Edwards and Haime, 1857, Hist. Nat. des Coral!., vol. iii, p. 102. BalanophyUia desmophyllum Quenstedt, 1881, Roliren-n. Sternkorallen, p. 1002. BalanophyUia desmophyllum Vangban, 1900, Mon. U. S. Geol. Survey, No. 39, p. 164, pi. xviii, figs. ll-13a. Description . — Corallum siibflabelliform, attached by a short pedicel, transverse outline elongate elliptical. Calice rather deep. Septa thin, in five cycles. The members of the first and second cycles with promi- nent upper margins. The margin of the third also exsert, but not to so great a degree as in the first and second cycles. The members of the fourth cycle have the least prominent margins. Those of the fifth cycle meet and unite in front of the fourth and then fuse to the sides of the third. They are very perforate. Their surfaces are granulate. There are no dissepiments. Costae rather fine, crowded together. Those corresponding to the first, second and third cycles coarser than those corresponding to the fourth and fifth cycles. Those costae correspond- ing to the fourth and fifth cycles fine, acute, present a serrate appear- ance when seen from the side, composed of a single row of granules; those corresponding to the first, second and third cycles of septa con- sist in their lower portion of a single row of granules, but in their upper portion of a double row. Branching by trifurcation. In old speci- mens the costae of the upper portion are wider and more granulated. Occasionally a septum of the fourth cycle will be fused distally to one of the second cycle and a single costa will correspond to the two septa. The perforations in the intercostal furrows are very close together. Wall rather dense, vesiculated. Epitheca rudimentary or absent. There may be an extremely thin pellicle of epitheca just above the place of attachment. Columella very well developed, spongy, vesiculated. Greater diameter of calice Lesser diameter of calice . Height of corallum 12 3 mm. mm. mnr. 14 13 23 8.5 8.3 16.5 18.5 17.5 28.5 The siibflabellate form of this species easily separates it from the other older Eocene species of BalanopliyUia in the United States. MARYLAND GEOLOGICAL SURVEY^ 229 I have compared our American material very carefully with the descriptions and figures of B. desmopJiyllum given by Milne-Edwards and Haime, and when in London, in January, 1898, I had the oppor- tunity to examine the types of the species. I have been unable to find any character by which the American specimens can be separated from those from Bracklesham beds, England. Milne-Edwards and Haime give an account of the affinities of B. desmopliyllum for the other Euro- pean species of the genus in their Monograph of the British Fossil Cor- als. Their work can be consulted for these notes. Occurrence. — Aquia Formation. 1 mile southeast of Mason Springs. Collection . — Maryland Geological Survey. Genus EUPSAMMIA Milne-Edwards and Haime. Eupsammia elaborata (Conrad). Plate LXI, Figs. 12, 13, 13a, 14, 14a. Turhinolia elaborata Conrad, 1846, Proc. Acad. Nat. Sci. Phila. , vol. iii, p. 22, pi. i, fig. 30. Osteodes elaborata Conrad, 1866, Check List, p. 2. Osteodes elaborata de Gregorio, 1890, Mon. de la faune eocenique, de PAla., p. 25. (.^) Placosmilui (Trocltosmilia) co7inivens De Gregorio, 1890, Mon. de la faune eocenique de PAla., p. 255, pi. xliv, figs. 25-28. Eupmramia elaborata Vaughan, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 6. Eupsammia elaborata Vaughan, 1896, Bull. 141, U. S. Geol. Survey, p. 90. Eupsammia elaborata Vaughan, 1900, Mon. U. S. Geol. Survey, No. 39, p. 180, pi. xxi, figs. 3-7. Description . — The folloiving brief description is based on the original type of Conrad. It bears the label, written by Conrad, “ Osteodes elaborata Con., Claiborne, Ala.'’^ This specimen is in the Academy of Natural Sciences of Philadelphia. Corallum compressed, conical, straight; cross-section elliptical, no in- dication of attachment. Costae rather fine, show perforations; branch by trifurcation. No epitheca. Wall perforate, spongy. Septa thin, in five cycles, anastomosing as usual in Eupsammia. Columella spongy. Greater diameter of calice, 12 mm.; lesser diameter of calice, 9 mm.; length of corallum, 13 mm. 230 SYSTEMATIC PALEONTOLOGY Locality, Claiborne, Alabama/ The following description is based on material from G-reggs Land- ing, xVlabama, in the United States National Mnsenm: The corallnm is snbconical or subcnneiform, the cross-section is ellip- tical. The base is -rather obtnse, usually rounded; very frequently on the tip is a minute scar, showing that the corallnm, in its early stages at least, is attached. The adults are evidently free, and the basal scar may be obliterated. The coralla are usually straight, but sometimes the apex of the base may be nearer to one end of the long transverse axis than to the other. There is no epitheca. The costae correspond to all septa; they are equal, fine and crowded; they are acute, with beaded margins; nearly always have along the summit a single row of granules; extremely rarely the row may be double for a short distance. The. septa are thin, weak, arranged in five complete cycles, six systems, with the typical Eupsammid scheme of anastomosing. The granulations on the septal faces are rather low. The columella is lax, spongy, fairly well developed. 12 3 mm. mm. . mm. Greater diameter of calice 13 14 12 Lesser diameter of calice 10 11.5 10 Height 17.5 18.5 14 + The specimens from Virginia are usually more slender than those from Alabama. Fig. 12 represents one of these slender specimens. The folloAving is M. de Gregorio’s original description of Placosmilia (Trochosmilia) connivens de Gregorio. Tr. conoidea, simplex, elegans, calice elliptico, paulo excavato; septis nnmerosis in 6 cyclos dispositis, laminaribiLs, tenuibis, valde angulosis spinulosisqiie, apud columellam vix incrussatis; columella carente vel cellulosa, ficta; costulis exterioribus confertis, miniitis, granulosis.” Translation: Tr. conoid, simple, elegant; calice elliptical, slightly excavated; septa numerous, disposed in 6 cycles, thin, delicate, with very sharp minute spines, thickening near the columella; columella ab- ' Doubtful. It is probable that Conrad has assigned a wrong locality to the specimen. MARYLAND GEOLOGICAL SURVEY 231 sent or cellular, false; external costae crowded together, minute, granu- lar/^ The description suits Eupsammia elaborata except for the number of cycles of septa, and the columella is never absent. E. elaborata has only five cycles of septa. M. de Gregorio's figures for the side view of his spe- cies, and the outlines of the calice, answer for E. elaborata, and only five cycles of septa are represented. In the arrangement of the septa, how- ever, his drawings do not represent what is found in Conrad’s specie^. The septal diagrams given by M. de Gregorio for other species of corals that I know well are not accurate, so it is not improbable that these like- wise are not correct representations of what is found in the specimens. I believe that M. de Gregorio has redescribed E. elaborata. Occurrence. — Aquia Formation. Potomac Creek, Aquia Creek, Marlboro Point, Upper Marlboro, 1 mile southeast of Mason Springs. Collections. — Philadelphia Academy of Natural Sciences, Mar}dand Geological Survey, Johns Hopkins University. Eupsammia conradi Vaughan. Plate LXI, Figs. 15, 15a, 15b. TurhinoUa pileolm Conrad, 1843, Proc. Acad. Nat. Sci. Phila., vol. i, p. 837. Tiirhinolin pileolus Conrad, 1846, Proc. Acad. Nat. Sci. Phila., vol. iii, p. 22, pi. i, iig. 26. EupHiimmia pileolHn Vaughan, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 6. Eupmmmia {^) pileolm Vaughan, 1896, Bull. 141, U. S. Geol. Survey, p. 90. Eapmimnia conradi Vaughan, 1900, Mon, U. S. Geol. Survey, No. 30, p. 183, pi. XXI, tigs. 10-10?). Not TurhinoUa pileolus Eichwald, Zool. Spec., pt. i, 1839, p. 186, pi. iii, tig. 1. Description. — Shape, like a very short cylinder set on a hemisphere. The basal portion is very slightly conical, rounded. Very faint costae. Wall thick, vesiculate. Septa thick, in four cycles; those of the fourth cycle fuse to the sides of the third, near the wall. The first three cycles reach the columella. Sides granulate; columella vesiculate. Greater diameter, 13 mm.; lesser diameter, 11.3 mm.; height, 11 mm. AVe know but little of this species; only one specimen seems to have been found, and that one is very unsatisfactory. I have referred it to the genus Eupsammia from the strong resemblance of its septal arrange- 232 SYSTEMATIC PALEONTOLOGY ment to that of young forms of other species. There is a faint scar on the hasC;, which may he due to attachment in its early stages. More information concerning this interesting little form will he welcomed. Occirrrence.— N anjemoy Fokmation. Pamnnkey Eiver, Kent Co., Virginia. Collection . — Philadelphia Academy of Natural Sciences. ECHINODERMATA. CL.SS ECHINOIDEA. Subclass ECHINOIDEA. Order SPATANGIDEA. Family SPATANGIDAE. A few fragments of the tests of spatangoid forms have been obtained from the Eocene of the Middle Atlantic Slope. It is not possible to determine their generic relations. A single fragment is figured (Plate LXI, Fig. 1). Occurrence . — Nanjemoy Formation. Evergreen, Va. Collection . — Johns Hopkins University. Orders DIADEMATOIDA and CIDAROIDA. Families DIADEMATIDAE and CIDARIDAE. Numerous spines belonging either to diadematoid or cidaroid forms have been found in the Eocene deposits of Maryland but they are not sufficiently distinctive to admit of generic determination. A single specimen is figured (Plate LXI, Fig. 2). Occurrence . — Aquia Formation. Upper Marlboro, Potomac Creek. Sheckels Farm near South Piver. Severn Eiver. Collections . — Johns Hopkins University, Mar}dand Geological Survey. MARYLAND GEOLOGICAL SURVEY' 2 ; 3;3 PROTOZOA. Class RHIZOPODA. Order FORAMINIFERA. Family TEXTULARIDAE. Genus TEXTULARIA Defiance. Textularia gramex d'Orbigny. Plate LXII, Fig. 1. Textularia gramen d’Orbigny, 1846, Foram. Fossiles Vienne, p. 248, pi, xv, ligs. 4-6. Textularia gramen Brady, 1884, CRal. Kept., vol. ix, p. 365, pi. xliii, ligs. 9, 10. Textularia gramen Bagg, 1898, Cret. Foram. New Jersey, Bull. 88, U. S. Geol. Sur- vey, p. 29. Description . — Test arenaceous, rough, stoutly built, laterally com- pressed, margin subangular; normally composed of five to seven wide chambers (in our Eocene specimens of nine or ten) in each series, which are but slightly convex; posterior end neatly rounded and in general outline very similar to T. hauerii, but differing from that species by its more angular lateral edges, and distinguished from T. abbreviata, which it also resembles, in being less short and thick. The little specimens of this Textularia from the localities of the Eocene below agree well in general characteristics with typical forms except in the greater number of chambers. They are composed of finely agglutinated grains well-rounded and smoothed over and the shells are quite compactly built for this species. The sutures are slightly depressed giving thus some relief to the chambers, especially to the final ones. This is a rare form in the Eocene of Maryland though common in the Pliocene of ATrginia. In present oceans it occurs in nearly all latitudes hut is commonest on shallow bottoms. Occurrence . — Aquia E’ormation. Upper Marlboro, 1 mile northeast of Piscataway. Collections . — Maryland Geological Survey, Johns Hopkins University. 234 SYSTEMATIC PALEOXTOLOGA' Textulaeia sagittula Defrance. Plate LXII, Fig. 2. Textularia sagittula Uefrance, 1824, Diet. Sci. Nat., vol. xxxii, p. 177; 1828, vol. liii, p. 344; Atlas Conch., pi. xiii, ttg. 5. Textularia sagittula Brady, 1884, dial. Kept., vol. ix, p. 361, pi. xlii, figs. 17, 18. Textularia sagittula Bagg, 1898, Bull. Amer. Pal., No. 10, p. 20. Description . — Test elongated, strongly compressed, with sharp-angled peripheral margin; chambers numerous, about ten to twelve in each series in typical forms, closely set, separated by short, nearly straight septal lines externally visible; aperture linear. Specimens of this form occur also in the Cretaceous (Rancocas) of New Jersey. It is rare in the Eocene of Maryland as are all species of the Textularia type. Three specimens have been recognized from Upper Marlboro. In present oceans this is one of the most wide-spread and commonest of all the Textnlaridae and Brady states that the same is time among the fossil Foraminifera. This may be attributed to the thick and solid walls, which, though not definitely arenaceous are so compactly hnilt of opaque material that they are more readily preserved than more delicate types. It is a shallow water species of temperate seas hilt is reported by Professor Brady to occur in the North Atlantic at the depth of 2675 fathoms and at 1425 fathoms in the South Atlantic. It occurs in the fossil condition in the Cretaceous formations of the north of Ireland (Wright), in the Cretaceous of New Jersey, the Eocene of the London Basin (Jones, Parker and Brady), the Lower Eocene of the Thanet beds of Pegwell Bay (Burrows), the Miocene of Austria, France, and elsewhere (d'Orbigny, Czjek, etc.), Miocene of Maryland and Virginia (Bagg), the later Tertiaries in Italy (Def ranee, Jones and Parker, d'Orbigny), the Crag of England (Jones, Parker and Brady), and the Post-Tertiary beds of Norway, Scotland, and Ireland (Sars, Robert- son, Wright). Occurrence. — Aquia Foemation. Upper Marlboro. Collections . — Johns Hopkins LTniversit}^ Maryland Geological Survey. Textulaeia subaxgulata d'Orbigny. Plate LXII, Fig. 3. Textularia subangulata d’Orbiguy, 1846, Foram. Fossiles Yienue p. 247, pi. xv, figs. 1-3. MARYLAND GEOLOGICAL SURVEY 235 Textuhiria subangulata Egger, 1857, Neues Jalirb.. fiir Miu. etc., p. 293, pi. xii, tigs. 15, 16. Textularia subangulata Bagg, 1898, Bull. Amer. Pal. No. 10, p. 20. Description . — The test of Textularia subangulata closely resembles T. granien, but it is separated from that species by the more nearly straight sutures^ more angular edges, and in typical forms by its larger number of chambers. The one specimen of this form from the Brook’s Estate near Seat Pleasant, while it may possibly be considered as a variety of the more widespread T. gramen differs so markedly from the common form that it has been placed with the present species. d’Orbigny’s specimens came from the Miocene of Austria, Egger’s from the Miocene of Ortenburg. Occurrence. — Aquia Formation. Brooks Estate near Seat Pleasant. Collection. — Johns Hopkins University. Genus SPIROPLECTA Ehrenberg. Spiroplecta clarki Bagg. Plate LXII, Fig. 4. spiroplecta clarki Bagg, 1895, Johns Hopkins Univ. Circ., vol. xv, p. 5. Spiroplecta clarki Bagg, 1896, Bull. Ill, U. S. Geol. Survey, p. 91. Spiroplecta clarki Bagg, 1898, Bull. Amer. Pal., No. 10, p. 20, pi. i, tig. 1. Description. — Test elongate, textulariform, finely arenaceous, firmly cemented; compressed strongly, lateral margins sharp and very slightly lobed; surface of shell rough, of a dull gray color; chambers at first planospiral then l)iserially arranged with nine and ten respectively on each side; aperture a median arched opening; length, 0.53 mm.; breadth, 0.20 mm. Previous to the author's discovery of the above Foraminifera the genus Spiroplecta has never been reported from the Tertiary formation so far as known. It has, liowever, been described from the Cretaceous of Mississippi (Ehrenberg), and of ^Minnesota (Woodward and Tliomas), and from the Gault and Clialk of England (Parker and Jones). Brady reports its occasional presence in existing oceans confined to three spe- cies, S. annectens, S. hiformis, and S. americana, the latter found living only in one locality oft' Raine Island. Torres Strait at the depth of 155 fathoms. 236 SYSTEMATIC PALEONTOLOGY Joseph Wright includes the genus Spiroplecta in the list of Post- Tertiary Foraminifera from the North of Ireland. The two specimens which the writer found at Woodstock seem to he new though they resemble 8. biformis of Parker and Jones. They are separated from that species^, however, by their sharp angular edges. The distal end is more obtusely rounded than in Textularian types and the chambers are less regularly developed. Occurrence. — Nanjemot: Formation. Woodstock. Collection. — Johns Hopkins University. Family LAGENIDAE. Subfamily NODOSARIDAE. Genus NODOSARIA Defrance. Nodosaeia aefinis (d’Orbigny). Plate LXII, Fig. 5. Deutalina ajffinis d’Orbigny, 1810, Mem. Soc. Geol. France, vol. iv, p. 13, pi. i, tig. 4. Nodosaria ajffinis Sherborn and Chapman, 1886, Jour. Roy. Microsc. Soc., 2nd series, ■vol. vi, p. 748, pi. xiv, fig. 38. JSfodomria affinis Bagg, 1896, Bull. 141, U. S. Geol. Survey, p. 91. Nodomria affi7iis Bagg, 1898, Bull. Amer. Pal., No. 10, p. 24. Descriptiofi. — Test very large, nearly straight, more tapering than Nodosaria bacillum, and without having the primordial chamber larger than the succeeding one; proximal end acuminate; chambers numerous, nnconstricted below but becoming distinctly so above; surface marked by about ten distinct elevated costae as in N. bacillum; aperture central, elevated on the ultimate chamber. Length 9 mm. or more. Occurrence. — Nanjemoy Formation. Woodstock. Collection. — Johns Hopkins Hniversity. Nodosaria bacillum Defrance. Plate LXII, Fig. 6. Xodosm'ia bacillum Defrance, 1825, Diet. Sci. Nat., vol. xxxv, p. 127; vol. xxxvi, p. 487, Atlas Conch., pi. xiii, fig. 4. Nodomria bacillum Bagg, 1896, Bull. 141, U. S. Geol. Survey, p. 91. Nodomria bacillum Bagg, 1898, Bull. Amer. Pal., No. 10, p. 24. Description. — Test very large, straight or nearly so, surface marked by about ten very distinct snow-white costae, though this number does MAEYLAXD GEOLOGICAL SGRYEY 23T not remain constant, some specimens liaying only eight costae below and as many as twelve above; primordial chamber bulbons, acuminate, though the spine is frequently broken; segments regular, less distinct below, marked by straight, transverse septae ; length unknown but frag- ments of nine chambers measure 5 mm. This Nodosaria has been described from a number of Tertiary de- posits of Europe and England but is seldom found in modern oceans, though Schlumberger mentions it from the Gulf of Gascony. It is, like all Nodosaria, not at all common in the Eocene deposits of the Middle Atlantic Slope. Occurrence. — ^Iaxjemoy^ Formatiox. Woodstock. Aquia Forma- Tiox. 3 miles west of Leeland, 2 miles below Potomac Creek, 1 mile southeast of Mason Springs, Upper Marlboro. Collections. — Johns Hopkins University, Maryland Geological Survey. Nodosaria commuxis (d'Orbigny). Plate LXII, Fig. 7. Bentalma communis d’Orbigny, 1826, Ann. Sci. Nat., vol. vii, p. 254. Bentalina communis 3 OTies and Parker, 1860, Quart. Jour. Geol. Soc. London, vol. xvi, pi. xix, tigs. 25, 26. Xoclosaria communis Brady, 1884, Chal. Kept., vol. ix, p. 504, pi. Ixii, figs. 19-22. Nodosaria cornnuinis Bagg, 1896, Bull. 141, U. S. Geol. Survey, p. 91. Nodosaria communis Bagg, 1898, Bull. Amer. Pal., No. 10, p. 25. Description. — Test elongate, smooth, with depressed, oblique septa; primordial chamber larger than the one succeeding and in some of our specimens acuminate; ultimate chamber, elongate, tube-like; transverse section circular, aperture round, smooth, length 0.6 mm. The earlier description of this species was based on a single young form but since this time a number of other specimens have been found from Upper Marlboro. The typical forms of this species have the sutures depressed and the chambers all oblique, in some of the forms remarkably so. This is one of the most common Nodosaria in both fossil and recent state and has a world-wide distribution to-day. It includes a large number of variously described species with oblique sutures such as D. inornata, and D. hadenensis, dUrbigny (Vienna Basin Monograph), D. lerjumen Peuss, D. snharcuaia AVilliamson and many others. 238 SYSTEMATIC PALEONTOLOGY Occurrence. — Aquia Formation. Brooks Estate near Seat Pleasant, Upper Marlboro. Collections. — Johns Hopkins University, Maryland Geological Survey. Hodosaeia consobrina VAR. emaciata (Keuss). Plate LXII, Fig. 8. Dentalma coiuobrina var. emaciata Reuss, 1865, Denkschr. d. k, Akad. Wiss. Wien, vol. XXV, p. 132, pi. ii, tigs. 12, 13. Nodosaria co?isobrma, var. emaciata Brady, 1884, Ckal. Kept., vol. ix, p. 502, pi. Ixii, figs. 25, 26. Nodosaria consobrina var. emaciata Bagg, 1898, Bull. Amer. Pal., No. 10, p. 25. Description. — Test smooth, elongate, tapering gracefully, segments numerous, short, elongate oval; similar in outline to N. consobrina but more elongated and slender; septae somewhat depressed, transverse. The proximal chamber is rounded and ends in a nipple-shaped aperture. Both N. consobrina and the variety emaciata are found living in the Xorth Atlantic at depths ranging from 290 to 725 fathoms, and in the South Atlantic at 350 fathoms; off the Cape of Good Hope, 150 fath- oms; and in the South Pacific, 129-1375 fathoms.^ This species has a vdde distribution in the fossil world. It is found in several formations of the Xew Jersey Cretaceous, according to Wright it occurs in the Chalk of Ireland, Jones and Parker report it in the London Clay, Eeuss, Bornemann, etc., record it in the Septaria Clays of Germany, the Miocene of Austria (d’Orbigny), the later Tertiaries of Italy (Costa), the Post-Tertiary of Norway (Crosskey and Eobertson), the Island of Ischia (Broeck), and in Scotland (Eobertson). Occurrence. — Aquia Formation. Upper Marlboro. Collection. — Johns Hopkins University. Nodosaeia sandbergeri (Eeuss). Plate LXII, Fig. 9. Dentalina sandbergeri Reuss, 1856, Sitzungsb. k. Akad. Wiss. Wien, vol. xviii, p. 224, pi. i, tig. 5. Description . — Test stoutly built, composed of from four to eight cham- bers which are constricted at the sutures; primordial chamber larger 1 Brady, Cbal. Rept., p. 502. MARYLAND GEOLOGICAL SURVEY 239 than the one succeeding, nltiinate chamber largest; chambers more con- stricted towards the oral end and none of them quite so strongly dis- tinct as in Eenss’ figure. Surface of shell strongly costate but differing from Eeuss’ specimens in that most of our forms have no costae upon the final segment, though this feature is not constant enough to make a new variety. The aperture is situated upon one side as in Marginu- lina types. Eeuss’ specimens were from the Tertiary deposits of Germany. Occurrence. — Aquia Formation. Upper Marlboro. Collection . — Maryland Geological Survey. XoDOSARiA OBLiQUA (Linue). Plate LXII, Fig. 10. Nautilus obliqnus Linne, 1767, Syst. Nat., 12th Edit., p. 1168, No. 281; 1788, Syst. Nat., 13th Edit. (Gmelin’s), p. 3372, No. 14. Nodosaria obliqua Brady, 1884, Chal. Kept., vol. ix, p. 1.513, pi. Ixiv, tigs. 20-22. Description . — Test variable in size, sometimes very large, elongate, tapering, arcuate; septal lines depressed, surface costate, costae varying in size and number in different specimens; chambers numerous, ventri- cose, distinct; aperture central, radiate. According to Professor Brady this species is found in every sea and at all depths from the laminarian zone down to 1500 or 2000 fathoms. It occurs frequently in the fossil state: Cretaceous of Sweden (Nillson), Cretaceous of Mecklenburg, and elsewhere (Eeuss), Cretaceous of New Jersey (Bagg), Lower Eocene, Thanet Beds, Pegwell Bay (Burrows), Tertiary of Germany (Eeuss, etc.). Tertiary of Italy (Costa). !Many other references could easily be given though these are sufficient to show its wide distribution. These forms are so large and long that one can find no perfect s])cci- mens as they are easily broken in collecting and washing the marl. The Cretaceous forms from Xew Jersey, however, are frequently perfect and well preserved. Occurrence . — Aquia Formation. Upper Marlboro (fragments only). Collection . — Maryland Geological Survey. 340 SYSTEMATIC PALEOXTOLOGA" Genus VAGINULINA Lamarck. Vagixulixa legumex (Linne). Plate LXIII, Fig. 1. JSFantilaa legumen Linne, 1758, Syst. Nat., 10th Edit., p. 711, No. 248; 12tli Edit., 1767, p. 1164, No. 288. Vaginnlina legumen Brady, 1884, Chal. Kept., vol. ix, p. 530, pi. Ixvi, figs. 13-15. Vagimilma leg\mien Bagg, 1898, Bull. Amer. Pal., No. 10, p. 26. Vaginnlina legumen Bagg, 1898, Cret. Foram. New Jersey, Bull. 88, U. S. Geol. Sur- vey, p. 52, pi. iv, fig. 4. Description. — Test nearly straight, pod-like, compressed, smooth, con- sisting of only six chambers; septa limbate, parallel, oblique, less dis- tinct towards the distal end; ultimate chamber slightly prolonged at the anterior end; aperture radiate; length, 0.80 mm. The genus Vaginnlina is closely related to the ensiform varieties of Crist ellariae and to the less flattened form Marginulina, and from the curved forms of Nodosaria from which it is separated by its broader outline and marginal aperture. Brady states that it is widely distributed over present oceans and that the genus reaches its greatest abundance in the North Atlantic. The species V. legumen is found at various depths down to 2000 fathoms hut it is commonest in shallow waters. Tate and Blake record this form from the Yorkshire Lias, Jones and Parker include it in the forms from the Upper Trias (?) of Chellaston, near Derby; Chapman records its occurrence from the Gault of Folke- stone; Burrows, Sherhorn and Bailey record it from the Bed Chalk of Yorkshire, etc., and many other localities are elsewhere given. Occurrence. — Aquia Fokmation. Brooks Estate near Seat Pleasant. Collection. — Johns Hopkins University. * Genus MARGINULINA d’Orbigny. Maeginulina costata (Batsch). Plate LXIII, Figs. 2, 3. JVautilufi {Orthoceras) costatus Batsch, 1791, Conchyl. des Seesaudes, p. 3, pi. i, figs 1 a-g. Marginulina costata Brady, 1884, Chal. Kept., vol. ix, p. 528, pi. Ixv, figs. 10-13. Description. — Test rather stoutly built, irregularly costate and costae curving about the distal end; compressed hut not strongly so; consist- MARYLAND GEOLOGICAL SURVEY’ 241 ing of six chambers, largest and most distinct at oral end, bluntly acu- minate, aperture on incurved side of final chamber. Brady says of this form, Individual specimens vary a good deal in contour, and also as to the number and degree of development of the superficial ribs; but the stout proportions of the shell, its subcylindrical form, and comparatively slight curvature, the inflated character of the later chambers, and the marginal aperture, are generally sufficient to distinguish it from costate varieties of Vaginulina and CristeJlaria. The test is usually more or less compressed just at the commencement, and occasionally presents a sharp or even subcarinate edge at the aboral end, but more frequently the margin is rounded from the beginning.” It is found in many parts of the North Atlantic at depths ranging from 370 to 1240 fathoms, from the South Atlantic at still greater depths, from the Mediterranean, and from the Adriatic. Save a few specimens found at 150 fathoms off the coast of New Zealand, it has not been observed in any portion of the Pacific ocean, in the Southern ocean or the Bed Sea. Occurrence. — Aquia Formation. Upper Marlboro. Collection. — Maryland Geological Survey. Genus CRISTELLARIA Lamarck. Cristellaria GIBB a dUrbigny. Plate LXIII, Fig. 4. Cristellaria fjihha d’Orbigny, 1839, Foram. Cuba, p. 63, pi. vii, ligs. 20, 21. Cristellaria excisa Bornemann, 1855, Zeitschr. d. deutsch. geol. Gesell., vol. vii, p. 328, pi. xiii, figs. 19, 20. Cristellaria palchella Reuss, 1862, Sitzungsb. d. k. Akad. Wiss. AVien, vol. xlvi, p. 71, pi. viii, fig. 1. liohulina concinna Reuss, 1863, Sitzungsb. d. k. Akad. Wiss. Wien, vol. xlviii, p. 52, pi. V, fig. 58. Cristellaria (fibha Bagg, 1898, Cret. Foram. New .Jersey, Bull. 88, U. S. Geol. Survey, p. 56. Descriptim. — Test oblong, biconvex, smooth, subcarinate, narrow; chambers few (seven or eight), slightly arcuate, separated by distinct septa; aperture marginate. Length (Cretaceous), 1.3 mm.; breadth, 0.87 mm. The septal face is rather sharply cut off from the whole surface and this feature separates it from Cristellaria acutauricularis which it 16 242 SYSTEMATIC PALEONTOLOGY closely resembles. Our Eocene forms have more chambers than the Cretaceous specimens of New Jersey which show nine. The mouth opening is also more prolonged and the sutures somewhat depressed be- tween the chambers. This species is found in many places in the Cretaceous of New Jersey, Eancocas (Bagg), Septaria Clays near Berlin (Bornemann), North Ger- man Hils and Gault (Keuss), and elsewhere. We must regard the species as an intermediate variety between the elongate compressed Cristellaria crepidula, and the symmetrical lenticu- lar Cristellaria rotulata. The form occurs in the North Atlantic and in the South Pacific at depths of less than 500 fathoms (Brady). Occurrence. — Aquia Fokmation. 1 mile northeast of Piscataway, Upper Marlboro. Collection. — Maryland Geological Survey. Ckistellakia eotulata (Lamarck). Plate LXIII, Fig. 5. Lenticnlites rotulata Lamarck, 1801, Annales du Museum, vol. v, p. 188, No. 3. — Tableau Eucycl. et Meth., pi. cccclxvi, tig. 5. Cristellaria rotulata d’Orbigny, 1810, Mem. Soc. geol. France, vol. iv, p. 26, pi. ii, tigs. L5-18. Cristellaria rotulata Parker and Jones, 186.5, Phil. Trans., vol. civ, p. 345, pi. xiii, tig. 19. Description. — Test involute, biconvex, smooth; peripheral margin sharp, non-carinate; chambers numerous, eight or nine in final convolu- tion; septa gracefully curved, visible externally as fine lines; aperture elliptical radiate. Diameter, 1-2 mm. While the above species is abundant in the Cretaceous of New Jersey and in the Eancocas reaching a large size for this type, it and all other Cristellariae are exceedingly scarce in the overlying Eocene. The type secured from Mason Springs is very large and thick-shelled. Since such a form would be readily preserved it is difficult to account for the lack of the species elsewhere while so many much more delicate Foram- inifera abound. It is doubtful if any Foraminifera is more widely distributed or more abundant either living or in fossil state than Cristellaria rotulata. MAEYLAXD GEOLOGICAL SUE VEIT 243 Brady records its presence in Arctic waters and as far south as Terra del Fnego and at the same time it occurs at all possible depths down to 2200 fathoms. So in the fossil world it is equally widely distributed. Jones and Parker record it in the Upper Trias of Derbyshire; Brady and Blake have identified it in every division of the Lias of England. It is frequently reported in the Cretaceous of England (Sherhorn, Chapman, IVnght, Sowerhy, etc.). It is abundant in every division of the Tertiary and has been frequently recorded. Occurrence. — xIquia Eoematiox. Upper Marlboro, 1 mile southeast of Mason Springs. Collection. — Maryland Geological Survey. Ceistellaeia eadiata (Bornemann). Plate LXIII, Fig. 6. Sobulina radiata Bornemann, 185.5, Zeitschr. d. deutscli. geol. Gesell., vol. vii, p. 834, p]. XV, fig. 1. Cristellaria radiata Bagg, 1896, Bull. 141, U. S. Geol, Survey, p. 91. GrUtellaria radiata Bagg, 1898, Bull. Amer. Pal., No. 10, p. 29, pi. i, fig. 3. Description. — Test nearly circular, moderately compressed, with cir- cular raised umbilicus; final convolution showing ten strongly curved, even chambers, marked externally by raised white septal lines which become less distinct toward the peripheral margin; keel quite definite and of the same snow-white character and color as the raised septa, while the chambers are darker in color and are strongly contrasted from the rest of the shell. The surface is smooth and glistening; the aperture radiate; diameter, 1.26 mm. Bornemann’s specimens of Cristellaria radiata were from the Oligo- cene (Septarienthon) of Germany. This form resembles Cristellaria rotulata but has the umbilicus raised, and the septa are also raised as they are not in Cristellaria rotulata. The keel is definite hut not pro- duced into a flange as in Cristellaria cultrata which form it closely re- sembles. Occurrence. — Xaxjemoy Foematiox, Woodstock. Collection. — Johns Hopkins University. 244 SYSTEMATIC PALEONTOLOGY Genus POLYMORPHINA d’Orbigny. POLYMORPHINA AUSTRIACA (d'Orbigliy). Plate LXIII, Fig. 7. GutUilina austriaca d’Orbigny, 1846, Foram. Fossiles Vienne, p. 223, pi. xii, ligs. 23-25. Polymorphina austriaca Sell wager, 1877, Boll. R. Com. geol. Ital., vol. viii, p. 25, pi. xxxi. Polymorphina austriaca Bagg, 1896, Bull. 141, U. S. Geol. Survey, p. 91. Polymorphina austriaca Bagg, 1898, Bull. Amer. Pal., No. 10, p. 28. Description. — Test oviform, smooth, moderately compressed, acum- inate anteriorly; consisting of four chambers which are oblong, oblique, and somewhat convex; separated by fairly deep sutures; aperture mam- millate. d^Orbigny considers that Guttulina nitida is closely related to this species but states that it differs from it in its more elevated chambers. Our specimens are slightly more acuminate posteriorly than in d’Or- bigny’s figure. Professor Brady lists this form among the synonyms of Polymorphina prohlema but d'Orbigny has shown that it differs from the latter by its more convex chambers and more gibbous form as a whole. Since the specific variations among the PolymorpJiinae are necessarily limited there is a possible danger of including too many variations under one species and it is preferable, therefore, to keep the species distinct as d^Orbigny has done. d'Orbigny^s specimens were from the Miocene of Nussdorf, Baden. It is not a common fossil form but Terquem has identified it among the Eocene Foraminifera of the Paris Basin. Occurrence. — Xanjemoy Formation. Woodstock. Collection. — Johns Hopkins University. Polymorphina communis (d’Orbigny). Plate LXIII, Figs. 8, 9. Guttulina communis d’Orbigny, 1826, Ann. Sci. Nat., vol. vii, p. 266, No. 15, pi. xii, ligs. 1-4. Modele, No. 62. Polymorphina communis Brady, 1884, Chal. Kept., vol. ix, p. 568, pi. Ixxii, flg. 19. Polymorphina comnmnis Bagg, 1896, Bull. 141, U. S. Geol. Survey, p. 92. Polymorphina communis Bagg, 1898, Bull. Amer. Pal., No. 10, p. 29. Description. — Test irregular, ovoidal, or egg-shaped; consisting of four or five distinct chambers; anterior end extremely acute, posterior obtuse; MARYLAND GEOLOGICAL SURVEY 245 chambers inflated, elliptical, embracing; surface smooth with definite septal depressions; aperture mammillate; diameter, 0.35 mm. This species occurs abundantly in the New Jersey Cretaceous but the forms are much larger than in the Eocene of Maryland. The species also occurs in the Pamunkey formation of Virginia on the Pamunkey River. This form is recorded from the Lower Lias (Blake); Septaria Clays of Germany (Reuss); Gault of Folkestone (Chapman); Lower Eocene of Pegwell Bay (Burrows); Red Chalk of Yorkshire, etc. (Burrows, Sher- born and Bailey); and many other references. Polymorpliina communis is closely related to Pohjmorpliina proUema^ and Professor Brady thinks that they should be united under one name of P. proUema and the name communis be allowed to drop. In the original models described by d’Orbigny (Nos. 61 and 62), the forms portrayed represent clearly distinct species, the first P. proUema shows about seven definite segments which are much inflated and with deep sutures while P. communis presents about four or five segments with less excavated sutures. In d^Orbigny’s great monograph on the Vienna Basin, both forms are included and the rather unimportant distinctions here seem to be that P. communis is of smaller size, the superior end acuminate and the su- tures are complanate while P. proUema shows an obtuse anterior, exca- vated sutures, larger size and more inflated chambers. Reuss considered in his notes on Herr von SchlichPs Septaria-clay Eoraminifera that P. communis is a variety of P. proUema and his con- clusion may be accepted ultimately, though for the present, it seems better to keep them distinct. Both forms have a wide distribution tbroughout all oceans but are apparently limited to a depth of less than 155 fathoms and so are shal- low water forms. It is also interesting to note that in the fossil world they frequently occur side by side and are variously described from the same localities. The genus Polymorpliina is represented by a good many forms of Eoraminifera as compared with other types but they never become abundant as do some of the involute genera. 246 SYSTEMATIC PALEONTOLOGY Occurrence. — N'anjemoy Formation. Woodstock. Aquia Forma- tion. Upper Marlboro. Collections. — Johns Hopkins University, Maryland Geological Survey. PoLYMORPHiNA COMPRESSA d’Orbigny. Plate LXIII, Fig. 10. Polyrnorphma compressa d’Orbiguy, IS46, Foram. Fossiles Vienne, p. 253, pi. xii, figs. 32-34. Polymorpldna compressa Brady, Parker and Jones, 1870, Trans. Linn. Soc. London, vol. xxvii, p. 227, pi. xl, tig. 12, a-f. Polyrnorphina compressa Bagg, 1890, Bull. 141, U. S. Geol. Survey, p. 92. Polyrnorphma compressa Bagg, 1898, Bull. Amer. Pal., No. 10, p. 29, pi. iii. ftg. 1. Description. — The shell or test of Polyrnorphina compressa is oblong, flatly compressed, inequilateral, with numerous fusiform chambers ar- ranged in a double series. Phiese are somewhat inflated and the sutures depressed. The surface of the shell is sometimes beautifully striated longitudinally, at others smooth or faintly striated. The aperture is variable, sometimes labyrinthic or porous but usually simple, circular and coronate. Its length is very variable, in our specimens from 0.82 to 1.3 mm., with a breadth of 0.43 mm. This species is very common in the Miocene of Maryland at Plum Point, Jones IVharf, etc., and also in the Miocene of Virginia. It is, however, not abundant in the Eocene. It has been identified from a well-boring in Norfolk, Va., at a depth of 685 feet. Professor Brady compares this form with its relatives as follows: In general terms Polyniorpliina compressa may be said to include the less regularly Textulariform varieties of the genus, its nearest allies being Polyrnorphina complanata d’Orbigny; Polyrnorphina frondiformis S. V. Wood; and Polymorphina cylindroides Roemer. Of these the first is distinguished by an exceedingly regular and equilateral Textularia- like disposition of the segments, and Polymorphina frondiformis by its even larger dimensions and its surface-ornament of interrupted costae or tubercles; whilst Polymorphina cylindroides has a long tapering test, less compressed than that of the present species and composed of a small number of nearly erect segments. , MARYLAND GEOLOGICAL SURYEA' 247 '' Pol iimorphina compressa is a cosmopolitan form, especially common in temperate latitudes. . . . It is abundant in the temperate portion of the Xorth Atlantic, j)referring shallow-water margins, hut extending sometimes to a depth of 400 to 600 fathoms. In the tropical South At- lantic- and in the Xorth and South Pacific it is less frequent. It has been recognized as a fossil in the lower and middle Lias of the west and north of England (Brady, Blake); in the lower Oolite, the L^pper Oxford Cia}', and the Kimmeridge Clay of England (Parker and Jones), and in the Cretaceous system of England, France, Germany, and Xorth America, and generally in the Tertiary and Post-Tertiary forma- tions of Europe.” Occurrence . — Xaxjemoy Formation. Woodstock, Well at Chesapeake Beach at 90-92 feet. Collections . — Johns Hopkins Hniversity, Maryland Geological Survey. PoLiTMORPHiNA ELEGANTissiMA Parker and Jones. Plate LXIII, Eig. 11. rohjiiiorpJnnn elegnntissima Parker aud Jones, 1865, Phil. Trans., vol. civ, p. 438, table 10. Pohjmorphina ehfpmtinsiina Brady, Parker and Jones, 1870, Trans. Linn. Soc. Lon- don, vol. xxvii, p. 231, pi. xl, tig. 15, a-c. Pohjmorphina elega)itinsima Bagg, 1896, Bull. 141, U. S. Geol. Survey, p. 92. Pohjmorphina elegantissima Bagg, 1898, Bull. Amer. Pal., No. 10, p. 30. Description. — Test ovoidal, anterior end acute, posterior ol)tusely rounded; chambers four or five, elongate, arranged in an inequilateral biserial manner and overlapping in such a way that while one side re- mains nearly flat the opposite is more or less irregularly vaulted and shows all the chambers in parallel arrangement; final segment broad below, embracing, and bearing the mammillate aperture upon the an- terior end. Shell surface smooth, finely perforate; length, 0.60 mm.; breadth, 0.40 mm. Professor Brady places under this species the form P. problema var. delfoidea Peiis.s, and P. anceps Penss. Occw/'/T/ice.— X anjemoy Formation. Woodstock. Collection . — Johns Hopkins University. 248 SYSTEMATIC PALEONTOLOGY POLYMORPHINA GIBB A (POrbignj). Plate LXIII, Fig. 12. Glohnlina gihha d’Orbigny, 1846, Foram. Fossiles Vienne, p. 227, pi. xiii, figs. 13, 14. PolyrnorpJdna gihha Brady, 1884, Chal. Kept., vol. ix, p. 561, pi. Ixxi, fig. 12. Polymorphina gihha Bagg, 1896, Bull. 141, U. S. Geol. Survey, p. 92. Polymorphma gihha Bagg, 1898, Bull. Amer. Pal., No. 10, p. 80. Description . — Test siibglobiilar, apex slightly produced; base obtusely rounded; consisting of from two to four chambers compactly joined and overlapping. The surface is smooth and unmarked by septal constric- tions. Septa visible as delicate, oblique lines; transverse section nearly circular; aperture mammillate; length of our specimens, 0.35 mm.; breadth, 0.30 mm. This is not a common species in the Eocene but the specimens are very similar to those from the Navesink formation (Lower Marl Bed) of the Xew Jersey Cretaceous. This form is very similar to PolymorpTiina lactea from which it is with difficulty separated. Its distribution is probably the same, both recent and fossil. Occurrence. — Xanjemoy Formation. Woodstock. Aquia Forma- tion. Upper Marlboro, Brooks Estate near Seat Pleasant. Collections . — Johns Hopkins University, Maryland Geological Survey. PoLYMORPHiNA LACTEA (Walker and Jacob). Plate LXIII, Fig. 13. Serpida lactea Walker and Jacob, 1798, Adam’s Essays (Kanmacher’s Edit.) p. 634, pi. xxiv, fig. 4. Poly t nor phina lactea Williamson, 1858, Recent Foram. Gt. Brit., p. 71, pi. vi, fig. 147. Polymorphina lactea Brady, Parker and Jones, 1870, Trans. Linn. Soc. London, vol. xxvii, p. 213, pi. xxxix, fig. 1, a-c. Description . — Test ovate or subpyriform, only slightly depressed, con- sisting of three or four chambers with flush sutures and scarcely distinct septal lines; aperture terminal, radiate; diameter, 0.39 mm. (Miocene). It is, as pointed out above, very difficult to separate this form from P. gilla. It is somewhat more graceful and slender and less obtuse and the MTiter believes that there is less good ground for separating these two forms than for distinguishing Polymorphma communis and Poly- MAKYLAXD GEOLOGICAL SUEVEY 249 morphina problema. The description of this form precedes P. gibba by nearly 50 years and if any change is made this must be given the prefer- ence and P. gibba be made a variety of Poly morphina lactea. Inasmuch as there is jnst as great danger of placing together many forms with varietal distinctions as there is in making too many species it is not at- tempted at the present time to change previous determinations and specific names. While fonnd in almost every sea it is more abundant in the shallow waters of temperate latitudes. It was not dredged by the Challenger in the North Atlantic at a greater depth than 400 fathoms but in the South Atlantic was fonnd at 1990 fathoms, North Pacific at 2300 fathoms. South Pacific, 2350; hut in all these cases the specimens are rare and of exceedingly small size, showing that they belong to shal- low water temperate zoneal forms. Its geological range is likewise wide and has been repeatedly recorded from the Jura, Cretaceous, and the various Tertiary deposits. It has been fonnd in the Miocene of Plum Point, where it is rare. Occurrence. — Aquia Foematiox. Upper Marlboro. Collection . — Maryland Geological Survey. PoLYMOEPHiNA PEAELONGA Terquem. Plate LXIII, Fig. 14. Polymorphina praelonga Terquem, 1878, Mem. Soc. geol. France, series 3, ^vol. i, p. 39, pis. iii, viii, figs. 20, 21. Polymorphina praelonga Bagg, 1896, Bull. 141, U. S. Geol. Survey, p. 92. Polymorphina praelonga Bagg, 1898, Bull. Amer. Pal., No. 10, p. 31. Description. — Test elongate oval, attenuated anteriorly; smooth and glistening; nearly circular in transverse section; three or four slightly raised, elongate chambers marked by somewhat depressed septa. Length, 0.79 mm. This species, with its many varieties of form, is beautifully illus- trated in Terqnem’s Monograph on the Eocene Foraminifera about Paris. It is said to he more abundant in the Eocene hut quite rare in de- posits of (later) Pliocene age. Occurrence. — Nanjemoy Foemation. Woodstock. Collection . — Johns Hopkins University. 250 SYSTEMATIC PALEONTOLOGY Family GLOBIGERINIDAE. Genus GLOBIGERINA d’Orhigny. Globigerina bulloides cEOrbigny. Plate LXIII, Figs. 15, 16, 16a. Globigerina bulloides d’Orbiguy, 1826, Ann. Sci. Nat., voi. vii, p. 277, No. 1 ; Modeles, No. 17 (young), and No. 76. Globigerina bulloides d’Orbigny, 1846, Foram. Fossiles Vienne, p. 163, pi. ix, figs. 4-6. Globigerina bulloides Brady, 1884, Cbal. Kept., vol. ix, p. 593, pi. Ixxvii, and pi. Ixxix, figs. 3-7. Globigerina bulloides Bagg, 1896, Bull. 141, U. S. Geol. Survey, p. 92. Globigerina bulloides Bagg, 1898, Bull. Amer. Pal., No. 10, p. 33. Description . — Test spiral, siibtrochoid; superior surface convex, in- ferior more or less convex but with deeply-sunken umbilicus; periphery rounded, lobulated; adult specimens composed of about seven globose segments, of which four form the outer convolution, the aperture of the individual chambers opening independently into the umbilical vestibule; diameter sometimes one-fortieth of an inch (0,63 mm.), but oftener much less.’^ (Brady, loc. cit.) While this species is not uncommon in the New Jersey Cretaceous it is rare in the Eocene. In New Jersey in the Manasquan (Upper Marl Beds) formation it is however much larger than in the Rancoeas, and. is 0.4 mm. in diameter in some specimens. In the Miocene of Maryland and Virginia it is also rather common but it is most abundant in the Miocene shell marls of Plum Point. In present oceans this species of Glohigerina is the commonest of all the Globigerinidae. In temperate zones it exists in enormous abundance and it does not seem to be limited in depth but occurs in dredgings all the way from shallow bottoms to the greatest depths. It is one of the few foraminifera which are truly pelagic in habit, that is, exist at the surface or in mid-water, for strange as it may seem, the majority of genera pass their existence at or near the bottom. Notwithstanding this fact that the great majority of foraminifera pass their existence near the bottom, the surface and middle water forms, far surpass the former in point of^numbers and are^resent in countless millions in all great oceans. It is interesting to note what genera and species belong ^^rAEYLAXD GEOLOGICAL SURVEY^ 251 to these surface forms and Professor Brady has prepared a list to show this feature. In this list we find seven species of Globigerinae, Orbiilina iiniversa, Ilastigeriua pelagica, PuUema ohliquiloculata, Sphaeroidina de~ hiscens, Candeina nitida, six species of Pnlvinulina, CymhaJopora hul- loides and CliilostomeUa ovoidea Eeuss. Occurrence. — ISTaxjemoy^ Formatiox. Woodstock, Well at Chesa- peake Beach at 90-92 feet. Collections. — Johns Hopkins University, Maryland Geological Survey. Family ROTALIDAE. Genus DISCORBINA Parker and Jones. Discorbixa bertheloti (d’Orhigny). Plate LXIY, Fig. 1. Rosalina bertheloti d’Orbigny, 1839, Foram. Canaries, p. 13.5, pi. i, figs. 28-30. I>isco7'bina bertheloti Bagg, 1896, Bull. 141, U. S. Geol. Survey, p. 9S. Discorbina bertheloti Bagg, 1898, Bull. Amer. Pal., No. 10, p. 34. Description. — Test very compressed, carinate, finely punctate; spiral side approximately flat, reverse side low-convex; chambers depressed, nu- merous, convex, margins slightly limbate; ultimate chamber larger than the one preceding. The shell is quite similar to Truncatulma lobatula, but it is more depressed, and the walls are more finely perforate; diame- ter, 0.42 mm. This is a shallow-water f oraminif era occurring usually at depths of less than 500 fathoms. Occurrence. — Xaxjemoy Formatiox. Woodstock. Collection. — Johns Hopkins University. Discorbixa turbo (d’Orbigny). Plate LXIV, Fig. 2. Rotalia {Troehulina) turbo d’Orbiguy, 1826, Ann. Sci. Nat., vol. vii, p. 274, No. 29; Modele, No. 73. JJiscorbina turbo Parker, Jones and Brady, 1865, Ann. and Mag. Nat. Hist., series 3, vol. xvi, p. 30, pi. ii, fig. 68. Discorbina turbo Brady, 1884, Chal. Kept., vol. ix, p. 642, pi. Ixxxvii, figs. 8, a, b, e. Description. — Test solidly built in a compact involute subconical form; walls rather coarsely perforated; six chambers visible on inferior surface t \ I 252 SYSTEMATIC PALEONTOLOGY with straight depressed septa between them and with the margin slightly lohnlated at their extremities. The inferior surface is flat or nearly so; superior side convex and several (three?) convolutions indistinctly visible. Septal lines rather sharply and gracefully curved and less definite as the primordial chamber is reached, which makes it difficult to tell how many chambers are present. Peripheral view a definite cone and aper- ture lying underneath the margin. Shell is of small size hut is very abundant in the Lower Eocene. This species is found in the Chalk of Maastricht (Parker and Jones), the Eocene of Paris (Terquem), etc. It is a shallow-w^ater foraminifera as is proved by the Challenger expedition which obtained the form at 420 fathoms (Ascension Island small forms), 350 fathoms off the coast of South America, at from two to ten fathoms at Port Jackson, Australia, and in the Bermuda coral sands. Occurrence. — Aquia Eokmation. Upper Marlboro. Collection . — Maryland Geological Survey. Genus TRUNCATULINA d’Orbigny. Truncatulina lobatula (Walker and Jacob). Plate LXIV, Fig. 3. N’autihts lobatulus Walker and Jacob, 1798, Adam’s Essays (Kanmacher’s Edit.), p. 642, pi. xiv, fig. 36. TrimcatuUna lobatula Brady, 1884, Chal. Kept., vol. ix, p. 660, pi. xcii, fig. 10; pi. cxv, figs. 4, 5. Truncatulina lobatula Bagg, 1896, Bull. 141, U. S. Geol. Survey, p. 92. Truncatulina lobatula Bagg, 1898, Bull. Amer. Pal., No. 10, p. 35. Description. — Test plano-convex, moderately vaulted; last volution consisting of seven, eight, or nine chambers with slightly depressed septa; septa more curved upon the superior (flat) surface; aperture a small, neatly-shaped arch at the margin of the ultimate segment. Diam- eter, 0.6 mm. Truncatulina lohatula shows great variation. Professor Brady con- siders that the more convex varieties merge into Truncatulina refulgens, MARYLAND GEOLOGICAL SURVEY 253 while flattened forms resemble Truncatulina wueJlerstorfi. The regular built convex varieties constitute Truncatulina boueana d’Orbigny and the less regular form the Truncatulina variabilis of the same author. T. variabilis is very well represented in the Miocene deposits at Plum Point, and elsewhere in the Atlantic Slope Miocene. Truncatulina lobatula is probably the most widely distributed of all the Foraminifera. In present oceans it occurs in every latitude from the Arctic waters to the Antarctic Ice barrier. It is most frequent in shallow waters but is present also at depths of 3000 fathoms. Its geological distribution begins with compact solid forms as far back as the Carboniferous and it is recorded in subsequent formations down to the present day. Occurrence. — Xaxjemoy Formation. Woodstock. Aquia Forma- tion. Upper Marlboro. Collections. — Johns Hopkins University, Maryland Geological Survey. Truncatulina ungeriana (d’Orbigny). Plate LXIV, Fig. 4. JRotalina iingeriana d’Orbigny, 1846, Foram. Fossiles Vienne, p. 157, pi. viii, tigs. 16-18. Truncatulina linger iana Brady, 1884, Clial. Kept., vol. ix, p. 664, pi. xciv, fig. fi, a-r/. Description. — Test large, rotaliform, circular, coarsely porous, both sides moderately convex, unequal, depressed slightly on the inferior side at the umbilicus; consisting of three convolutions. The last \olution composed of ten to twelve chambers. Septa arched; aperture a median slit of semilunar shape. Diameter, 0.T8 mm. This species is common in the Rancocas formation of the New Jersey Cretaceous and it is fairly abundant in the Lower Eocene of Upper Marl- boro, near Seat Pleasant and elsewhere. In the Xorth Atlantic Truncatulina ungeriana is fairly abundant at from 90 to 600 fathoms, and while it has been found in the South Pa- ciflc at depths from 27 to 2600 fathoms it is nevertheless a shallow-water form. Specimens occur in the Lower Eocene of Pegwell Bay, England (Burrows) and in the London Clay, and it is recorded in the later Ter- tiaries of southern Europe. 254 SYSTEMATIC PALEONTOLOGY Occurrence. — Aquia Formation. Upper Marlboro, Brooks Estate near Seat Pleasant, Well at Chesapeake Beach at 90-92 feet. Collection . — Maryland Geological Survey. Genus ANOMALINA d’Orbigny. AnOM ALINA AMMONOIDES (Eeuss). Plate LXIV, Fig. 5. Romlina ammonoides Reuss, 1845-46, Verstein. bohm. Kreide, i, p. 36, pi. viii, fig. 53 ; pi. xiii, fig. 66. Anomalina ammonoides Bradj^ 1884, Cbal. Kept., vol. ix, p. 672, pi. xciv, figs. 2, 3. Anomalina ammonoides Bagg, 1898, Bull. 88, U. S. Geol. Survey, p. 67, pi. vi, fig. 5. Description . — Test nautiloid, coarsely porous, small, compressed; lat- eral surface nearly equally convex; depressed at the umbilici; peripheral edge round; aperture an arched nearly median opening upon the inner margin of the ultimate segment. Diameter, 0. 5-0.8 mm. In the Xorth Atlantic off Bermuda good specimens of Anomalina ammonoides were taken by the Challenger expedition but no other speci- mens were found in the North Atlantic. These were at the depth of 435 fathoms. It was recognized in dredgings in the South Pacific at the depths of 210 fathoms (near the Fiji Islands), also at 1350 fathoms from the same vicinity, 275 fathoms off New Zealand, and another in Humboldt Bay at 37 fathoms. Parker and Jones obtained it from the Red Sea at depths of 372 and 678 fathoms, also in anchor muds near Ilong Kong and shore sands at Melbourne. It is common as a fossil from Cretaceous time on through the Tertiaries. Occurrence. — Aquia Formation. Upper Marlboro. Collections . — Johns Hopkins University, Maryland Geological Survey. Anomalina grosserugosa (Gtimbel). Plate LXIV, Fig. 6. Trmicatulina (jrosserugosa Giimbel, 1868, Abhandl. d. k. bayer. Akad. Wiss., vol. x, p. 660, pi. ii, fig. 104, a, h. Anomalina grosserugosa Brady, 1884, Cbal. Rept., vol. fix, p. 673, pi. xciv, figs. 4, 5. Anomalina grosserugosa Slierborn and Chapman, 1889, Jour. Royal Microsc. Soc., p. 487, pi. xi, fig. 24. Anomalina grosserugosa Bagg, 1898, Bull. 88, U. S. Geol. Surve}', p. 67, 'pi. vi, fig. 4. Description . — Test nautiloid, very coarsely porous, pores larger and more numerous upon the inferior surface; both sides convex; umbilici MARYLAND GEOLOGICAL SURVEY distinct; peripheral margin round; chambers large, inflated; only eight in final convolution; septa nearly straight; aperture median, arched. Diameter, 0.43-0.82 mm. Though occurring in the Cretaceous the form is more frequently re- corded in Tertiary deposits. Good recent specimens were secured by the Challenger in the Xorth Atlantic at depths of 450 to 1000 fathoms, in the South Atlantic at 420 to 1415 fathoms, in the South Pacific at 610 and 2160 fathoms, and in the I^orth Pacific at 325 and 2050 fathoms. Occurrence. — Aquia Formation. 1 mile northeast of Piscataway. Collection . — Maryland Geological Survey. Genus PULVINULINA Parker and Jones. PULVINULINA EXIGUA VAR. OBTUSA BurrOWS. Plate LXIV, Fig. 7. Pnlvinnlina exigua var. ohtusa Burrows, 1S97, Proc. Geol. Assoc, (and reprint), vol. XV, pts. i, ii (Marcli-May), p. 49, pi. ii, tig-. 25 in reprint. Description . — Test free, rotaliform; both faces convex and generally equally so; composed of three convolutions, of which the outermost has usually five segments. Sutures non-limbate, marked on the superior face by thickened lines of opaque shell-substance; on the inferior by slight depressions; periphery olfiuse, and very rarely lobulated.’’ Bur- rows, 1897. According to the above author P. exigua var. ohtusa is next to Bull- mina elongata the most common foraminifera of the Thanet Sands (Lower Eocene). Our specimens agree closely with the figure of Burrows’ varieties of Pulvinulina exigua as figured by Professor Brady, but there are six in- stead of five chambers in the final convolution and the form is not quite so obtuse as the type forms. The perfectly straight septa so obliquely set upon the superior surface are more distinct in the outer convolution. Upon the inferior side these run straight to the center of the umbili- cus. The type of the species {P. exigua) is regarded as a deep water form. In the Challenger expedition it v'as obtained at depths ranging 256 SYSTEMATIC PALEONTOLOGY from 64 to 2740 fathoms but it is quite possible that this variety of the form is not to be so regarded. Occurrence. — Aquia Fokmation. 1 mile northeast of Piscataway. Collection . — Maryland Geological Survey. PuLViNULiNA SCHREIBEESII (d’Orbigny). Plate LXIV, Fig. 8. Eotalina schreihersii d’Orbigay, 1846, Foram. Fossiles Vienne, p. 154, pi. vii, tigs, 4-6. Pulvinulina schreiberaii Bagg, 1896, Bull. 141, U. S. Geol. Survey, p. 92. Palvinnlina schreihersii Bagg, 1898, Bull. Amer. Pal., No. 10, p. 37, pi. xxiii, tig. 2. Description. — Test orbicular, superior side more convex than inferior; consisting of about seven chambers in the final convolution (some speci- mens show nine); inferior side distinctly stellate with depressed septal lines and elevated chambers, the latter feature being characteristic for the species and distinguishing it from Pulvinulina harsteni, by lack of peripheral keel. The final chamber is larger and more globose than the one adjoining; umbilicus depressed on the inferior side; aperture a sub- marginal slit; diameter, 0.4-0.54 mm. This species is not uncommon in the Eocene of Woodstock but seems to be quite rare in the Miocene of James Kiver, Ya. Eeferring to the depth at which this species is found in present oceans Professor Brady says in the Challenger Eeport — off New Hebrides 125 fathoms; off Ki Islands, 129 fathoms; southwest of Papua, 28 fath- oms; oft Eaine Island, 155 fathoms; off Cape York, Torres Strait, 3-11 fathoms; Humboldt Bay, Papua, 37 fathoms; and off Admiralty Islands, 17 fathoms; ... off Bermuda, 435 fathoms. Parker and Jones record its occurrence in the Eed Sea, 40 fathoms, and in the Mediterranean, 90 fathoms.^^ Occurrence. — Hanjemoy Formation. Woodstock, lYell at Chesa- peake Beach at 90-92 feet. Collections . — Johns Hopkins Universit}^ Maryland Geological Survey. MARYLAND GEOLOGICAL SURVEY 257 Genus NONIONINA d’Orbigny. Nonionina afeinis Eeuss. Plate LXIV, Fig. 9. Nonionina affitiis Reuss, 1851, Sitzungsb. d. k. Akad. Wiss. Wien, vol. iii, p. 72, pi. Vj flg. 32. Nonionina affinis Bagg, 1896, Bull. 141, U. S. Geol. Survey, p. 92. Nonionina affinis Bagg, 1898, Bull. Amer. Pal., No. 10, p. 39, pi. i, fig. 5. Description . — Test small, orbicular, strongly compressed, umbilicate, finely perforate; chambers ten to twelve, small, fiat, slightly curved, sep- arated by fairly distinct band-like septal lines; septal plane of ultimate chamber somewhat higher than broad and quite large; aperture short, semilunar. Diameter, 0.32 mm. Professor Eeuss’ figure agrees fairly well with our specimens but there are twelve chambers visible in the last volution. According to Eeuss this species is closely related to Nonionina punctata d’Orbigny, but the latter is thicker in transverse section. Occurrence. — Xanjemoy Formation. Woodstock. Collection . — Johns Hopkins University. Genus AMPHISTEGINA d’Orbigny. Amphistegina lessonii d’Orbigny. Plate LXIV, Fig. 10. Amphistegina lessonii d’Orbigny, 1826, (parte) Ann. Sci. Nat., vol. vii, p. 304, No. 3, pi. xvii, figs. 1-4. Amphistegina lessonii Brady, 1884, Chal. Kept., vol. ix, p. 740, pi. cxii, figs. 1-7. Amphistegina lessonii Bagg, 1896, Bull. 141, U. S. Geol. Survey, p. 92. Amphistegina lesso7iii Bagg, 1898, Bull. Amer. Pal., No. 10, p. 42, pi. i, fig. 6. Description . — Test circular, compressed, transverse elliptical; superior only slightly more elevated than the inferior; superior surface shows about eighteen angular segments; inferior surface less distinctly cham- bered, more irregular; chambers narrow, angular, visible in transmitted light; surface smooth and of a brownish-yellow color. Diameter, 1.47-2 mm. Professor Brady states that this species shows great variation in the amount of convexity. Our specimens agree more closely with his Fig. 4 17 258 SYSTEMATIC PALEONTOLOGY of Plate CVI, in the Challenger Eeport and may be considered as typical for the species. This is not a common form and only three specimens have been obtained at Woodstock and only a few are found in the Mio- cene of Darlington, S. C., nearly all of which are imperfect specimens. In existing oceans this form is commonest on bottoms of less than ^0 fathoms depth and is rare below 300 to 400 fathoms. It is more fre- quent in warm tropical waters. As a fossil it has been variously de- scribed from the Tertiaries of Europe, among them being the Eocene of the Paris Basin (Terquem), Upper Eocene of the Swiss Alps (Kauf- mann), etc. Occurrence. — Uanjemoy Eokmation. Woodstock. Collection . — Johns Hopkins University. PLANTAE. Carpolithus marylandicus n. sp. Plate LXIV, Figs. 11, 11a, 11b. Fruit irregularly ovate, about f inch long, broadest at the base, 4-valved (?); valves separating completely to the base; epicarp rough, somewhat warty, wrinkled or ridged longitudinally, about 1-16 inch thick, distinct from the smooth pericarp; seed cells about f inch long by -J inch broad, attenuate towards the apex of the fruit and rounded at the base. Carpolithus marylandicus yar. rugosus n. var. Plate LXIV, Figs. 12, 12a, 12b. Orbicular, about 7-16 inch in diameter, or less; warty, but without longitudinal markings; seed cells relatively broader to the length than in the species. The material upon which the descriptions and figures of Carpolithus are founded is exceedingly fragmentary, not one entire fruit being rep- resented in the collection. The drawings of the complete fruits were made by fitting together disconnected valves, and as these vary in size MARYLAND GEOLOGICAL SURVEY 259 the number of yalves into which the fruit was actually divided is un- certain. They may have been three or four or five, and for that reason the number is questioned in the description. The fruit resembles quite closely Pliymatocoryon mackayi Muell., from the auriferous drifts of Australia, described in the Eeport of the Geo- logical Survey of Victoria for 1874, p. 11, pi. ii, which is however defi- nitely 3-valved. The geological horizon of these drifts is considered as Pliocene. In this connection it may be of interest to note that the fossil fruit deposit of Brandon, Vt., described by Hitchcock (Commonwealth of Massachusetts, House Document Vo. 39, 1853, pp. 22-34; Amer. Jour. Sci., vol. XV, 1853, pp. 95-104) and by Lesquereux (Kept. Geology of Vermont, vol. ii, 1861, pp. 712-718; Amer. Jour. Sci., vol. xxxii, 1861, pp. 355-363) has been called by different authorities Eocene, Miocene, Pleiocene and Pleistocene. The general appearance of our material is quite similar to that from Brandon, being thoroughly lignitized, with the general form of the fruit preserved. The internal structure has, however, been more or less de- stroyed or altered and it has, therefore, not been possible to determine satisfactorily the probable botanical affinities. The only other record with which I am familiar, of similar material from the United States, is by Edmund Puffin (Amer. Jour. Sci., ser. ii, vol. ix, 1850, pp. 127-129) describing a fossil nut from the Eocene marl of Marlbourne, Va. Vone of the American species described or figured may be satisfac- torily identified with our specimens. I PLATES PLATE X. PAGE Fig-s. 1, 2. Tiiecachampsa sp 95 1. Dorsal view of dorsal vertebra. Liverpool Point. 2. Posterior view of same specimen. Fig. 3. Thecachampsa sericodon (?) Coj)e 95 Tooth. Clifton Beach. Fig. 4. Thecachampsa contusor Cope 96 4a. Lateral view of tooth. Aqiiia Creek. 4b. Basal view of same tooth. Fig. 5. Thecachampsa marylandica Clark 96 Fragment of jaw with tooth. Clifton Beach. Fig. 6. Eeptilian coprolite 96 From Clifton Beach. Fig. 7. Euclastes (?) sp 97 Costal plate. Clifton Beach. 263 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE X. REPTILIA, PLATE XI. PAGE Figs, la, lb. Trionyx virginiana Clark 97 Costal plates. Aqiiia Creek. Museum Wagner Free lust. Sci., Phila. 263 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE REPTILIA. PLATE XII. PAGE Figs. 1. 2 . Myliobatis copeanus Clark 99 1. Oral aspect of upper dental plate of an adult individual. The an- terior end is uppermost. Clifton Beach. 2. Portion of lower dental plate of an immature individual, showing two rows of lateral teeth and anterior depression due to wear. Clifton Beach. Fig. 3. Myliobatis magister Leidy 100 Oral aspect of a very large upper dental plate, the anterior end shown uppermost in the figure. Museum Comp. Zool., Cambridge. Ashley River, S. C. Figs. 4-6. Otolites of Teleostome Fishes 113 Pof)es Creek. X 4. Figs. 7a, 7b. Detached vertebral centrum of an indeterminate Tele- ostome fish 110 7a. Lateral view. Clifton Beach. 7b. End view of same specimen. Fig. 8. XiPHiAS (?) RADIATA (Clark) 112 Llypural fan as viewed from the left lateral aspect. Clifton Beach. 264 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XII. PISCES. PLATE Xlll. PAGE Figs, la, lb. Myliobatis magister Leidy 100 la. Transverse surface of the same sj)ecimen shown in Plate XII, Fig. 3. The anterior end is placed uppermost in the figure. lb. Attached surface of same specimen. Figs. 2a, 2b. Myliobatis copeanus Clark 99 2a. Transverse section. Liverpool Point. 2b. Attached surface, same locality. The anterior end is f>laced uiiper- most in the figures. Figs. 3a, 3b. Aetobatis arcuatus Agassiz 102 3a. Attached surface of detached tooth. Pof)es Creek. 3b. Lateral aspect of same sxiecimen. Fig. 4. Myliobatis sp 101 Transverse and longitudinal views of caudal siiine, Ashley lliver, S. C. Museum Comp. Zook, Cambridge. Fig. 5. Myliobatis sj) 101 Transverse and longitudinal views of caudal spine, Montgomery, La. Museum Coinj). Zook, Cambridge. Figs. 6, 7a, 7b. Myliobatis copeanus Clark 99 6. Nearly jierfect uxif)er dental xilate of a comxjaratively young indi- vidual; the anterior end shown up^iermost in the figure. Clifton Beach. 7a. Oral surface of lower dental i)late of a comjiaratively young indi- vidual with serrated sutures due to wear. Clifton Beach. 7b. Inferior asjiect of same specimen. Fig. 8. Aetobatis arcuatus Agassiz Oral surface of a detached tooth. Popes Creek. 102 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XIII. PISCES. PLATE XIV. PAGE Figs, la, lb. Odontaspis cuspidata (Agassiz) 105 la. Inner face of a tooth with well-developed lateral denticles. Liver- pool Point. lb. Outer face of same specimen. Figs. 2a, 2b, 2c, 3a, 3b, 3c. Odontaspis elegans (Agassiz) 104 2a. Inner face of a worn anterior tooth lacking its pair of lateral denticles. Liverpool Point. 2b. Lateral aspect of the same specimen. 2c. Outer face of the same specimen. 3a. Inner face of a well-preserved tooth showing prominent coronal striae. Aquia Creek. 3b. Lateral asiiect of the same specimen. 3c. Outer face of the same specimen. Figs. 4a, 4b. Odontaspis macrota (Agassiz) 105 4a. Outer face of a tooth. Liverpool Point. 4b. Inner face of the same specimen. Figs. 5a, 5b, 5c. Syneciiodus clarkii n. sp 103 5a. Inner face of a tooth. Liverpool Point. 5b. Lateral aspect of the same specimen, 5c. Outer face of the same specimen. Figs. 6a, 6b. Odontaspis cuspidata (Agassiz) 105 6a. Outer face of a tooth. Liverpool Point. 6b. Inner face of the same specimen. Figs. 7a, 7b. Sphyrna prisca Agassiz 110 7a. Inner face of a tooth. Liverxiool Point. 7b. Outer face of the same siiecimen.. Fig. 8. Galeocerdo latidens Agassiz 109 Outer face of a tooth. Woodstock. X 2 PISCES. PLATE XV. PAGE Figs. 1-4. Otodus obliquus Agassiz 106 la. Inner face of an anterior tooth belonging to an immature indi- vidual, and corresponding in size to the lateral tooth shown in Fig. 5. Liverpool Point. lb. Lateral aspect of same specimen. l c. Outer face of same specimen. 2a. Inner face of a lateral tooth belonging to an immature individual. Liverpool Point. 2b. Lateral aspect of same specimen. 2c. Outer face of same specimen. 3a. Outer face of a lateral tooth, with a well-develox^ed pair of lateral denticles. Aquia Creek. 3b. Lateral aspect of same specimen. 3c. Inner face of same specimen. 4a. Inner face of an unusually large and massive tooth with erect crown, entire edges and large lateral denticles, showing transi- tional characters between Carcliarodon and Larnna. Glymont. 4b. Lateral aspect of same specimen. 4c. Outer face of same si^ecimen. PISCES. PLATE XVI. Fig-s. 1-4. Bythocypris subaequata n. sp 1. Eight side of an entire carapace. Upper Marlboro. 2. Dorsal view of same. 3. Anterior view of same. 4. Inner side left valve showing internal marginal jilate. Figs. 5-8. Bythocypris parilis n. sp 5. Eight side of entire carapace. Upper Marlboro. 6. Ventral edge of same. 7. Inner side of right valve. 8. Inner side of left valve. Figs. 9-13. Cytiierella marlboroensis n. sii 9. Left side of a perfect carapace. Upper Marlboro. 10. Eight side of another specimen from same locality. 11. Dorsal view in outline of same. 12. Inner side of a right valve. 13. Anterior end view. Figs. 14-15. Cytherella submarginata n. sp 14. A left valve showing slight mesial depression and marginal Upper Marlboro. 15. Ventral view of same. Figs. 16-18. Cythere marylandica n. sp 16. Posterior end view of an entire caraxmce. Upper Marlboro. 17. Eight side of same. 18. View of ventral edge of same. Figs. 19-21. Cythereis bassleri n. sp 19. An average left valve of this species. 20. Ventral edge of an entire carapace. 21. Outline view of anterior end of same. Figs. 22-23. Cytheridea perarcuata n. sp 22. View of a right valve. 23. Ventral edge of same. All the figures are magnified 20 diameters. 268 PAGE 116 117 117 118 rim. 119 120 121 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XVI. ARTHROPODA CRUSTACEA. PLATE XVII. PAGE Hercoglossa tuomeyi n. sp 122 Lateral view of smaller tyi^e. Popes Creek. X % 269 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XVll- b MOLLUSCA CEPHALOPODA. PLATE XV HI. PAGE Hercoglofsa tuomeyi n. sp 122 Lateral view of larg-er type, showing fragments of shell substance with lines of growth. Popes Creek. X % 270 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XVIII- MOLLUSCA CEPHALOPODA. PLATE XIX. Fig-s. 1-3. Hercoglossa tuoaieyi n. sp 1. Peripheral view of specimen illustrated on Creek. 2. Specimen showing* frag-ment of shell substance Popes Creek. 3. Specimen showing* a fragment of shell from Clifton Beach. PAGE 122 Plate XVII. Popes X % from near periphery. X % near the umbilicus. MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XIX. MOLLUSCA CEPHALOPODA. PLATE XX. PArings. Fig. 9. Plefrotoma tysoai n. sp 12G Ventral view of type s])ecimen. 1 mile southeast of Mason Springs. Figs. 10, 11. Plefrotoma gtiiloreni Lea 127 10. Ventral view of broken sxtecimen. 1 mile southeast of INlason Springs. 11. Dorsal view of more nearly perfect individual. Fig. 12, Plefrotoma ptscatavensis n. sp 127 Dorsal view of type specimen. 1 mile northeast of Piscataway. Figs. 13, 13a. IMangilia (Plefrotomella) bellistrtata Clark 128 13. Ventral view of ty]te s])ecimen, enlarged as indicated. Popes Creek. 13a. Dorsal view of same sjtecimen, natnral size. MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XX. 4 MOLLUSCA— CEI>HAL()l'OI).\. PLATE XXI. PAGE Fig. 1. Cancellaria graciloides Aldrich var 128 Ventral view of specimen from 1 mile southeast of Mason Springs. Fig. 2. Cancellaria sp 129 Much enlarged view of specimen from 2 miles below Potomac Creek. Figs. 3, 3a. Cancellaria (Narona) potomacensis n. sp 129 3. Ventral view of specimen from 1 mile northeast of Piscataway. 3a. Dorsal view of same sj)ecimen. Pigs. 4, 5, 5a. Volutilithes petrosus (Conrad) 130 4. Pomonkey Neck. U. S. National Museum. 5. Dorsal view. Potomac Creek. 5a. Ventral view of same specimen. Figs. 6, 6a. Volutilithes sp 131 6. Ventral view of cast. Aqnia Creek. 6a. Dorsal view of same specimen. Figs. 7, S. Caricella pyruloides (?) (Conrad) 131 7. Spire and part of body whorl. Potomac Creek. 8. Cast. Aqnia Creek. Figs. 9, 9a. Mitra marylandica Clark 132 9. Dorsal view. Pomonkey Neck. U. S. National Museum. 9a. Ventral view of same specimen. Figs. 10, 10a. Mitra pomonkensis n. sp 132 10. Ventral view. Pomonkey Neck. U. S. National Museum. 10a. Dorsal view of same specimen. Fig. 11. Mitra potomacensis n. sp 133 Enlarged view. 1 mile northeast of Piscataway. Figs. 12, 12a. Latiriis marylandicus n. sp 133 12. Ventral view. 2 miles below Potomac Creek. 12a. Dorsal view of same speeimen. J73 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XXI. MOLLUSCA GASTROPODA. PLATE XXII. PAGE 134 Figs. 1, 2. Fusus (?) si'BTENX'is ITeilprin 1. Dorsal view of specimen with nearly ])erfeet spire. 2 miles below Potomac Creek. 2. Ventral view of another specimen with perfect month. Two miles below Potomac Creek. Fig. 3. Tropiion sublevis Harris 135 \hew of fragment, with outlined restoration. 1 mile northeast of Piscataway. Figs. 4, 4a. Fx^stis (?) interstriatits Heilprin 135 4. Ventral view of specimen. 1 mile northeast of Piscataway. 4a. Dorsal view of same sjxecimen. Figs. 5-8. Strepsidura subscalarina Heilprin 136 5, 6. Ventral views of specimens. 2 miles below Potomac Creek. 7. Potomac Creek. Acad. Xat. Sci. Phila. 8. Ventral view. 2 miles below Potomac Creek. 8a. Dorsal view. Same locality. Fig. 9. MELONGENA (?) POTOMACENSTS 11 . sp 136 Type. Potomac Creek. Acad. Xat. Sci. Phila. Lea .Memorial Coll. MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XXII. M ( ) LLU S C A G A ST R O P (3 1) A . PLATE XXIII. PAGE Fig'S, 1, la, lb. Tudicla marylandica n. sp 137 Ventral, dorsal and end views. 2 miles below Potomac Creek. Fig'S. 2, 2a. Tudicla sp 138 Ventral view. Crownsville. End view of the same specimen. Fig-. 3. Levifusus trareatus (?) Conrad var 139 Cast. Woodstock. Fig'. 4. Tudicla (?) sp 138 Cast. Aquia Creek. Fig. 5. Metula marylandica n. sp 139 Ventral view of type specimen. 2 miles below Potomac Creek. Fig. 6. Chrysodomus engonatus (Heilprin) 140 2 miles below Potomac Creek. Fig. 7. PSEUDOLIVA sp 140 Cast. Upper Marlboro. 375 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XXIII. MOLLUSCA — GASTROPODA. PLATE XXIV. Figs. 1, la. Tritonii'm siiowalteki ((’oiirad) 141 1. Ventral view. 2 miles below Potomae Creek, la. Dorsal view of the same specimen. Fig. 2. Pykula PENiTA var. Conrad 131 Ventral view with outlined restoration. Popes Creek. Figs. 3, 3a. Fulgukoficus argutus Clark 142 Type specimen. I’otomac Creek. Figs. 4, la. Fusoficula juvenis (Whitfield) 143 4. Ventral view. 2 miles below Potomae Creek. 4a. Dorsal view of the same specimen. Fig. 5. Pyrula (?) sp. 112 Body whorl. Ponies Creek. Fig. C. Tfdk'la (?) s]) 138 Po])es Creek. Morio rrevidentata (Aldrich) 144 Dorsal view. 1 mile southeast of IMason Springs. Fig. 8. Cypraea SMiTiii Aldrich 144 Specimen with outlined restoration, mile belo\v Cha])el Point. MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XXIV. 3 MOLLUSCA GASTROPODA. PLATE XXV. PAGE Fig’S. 1, la, 2. Calyptraphorus jacksoni Clark 145 1. Dorsal view of type. Sheckels Farm near South Eiver. la. Ventral view of same specimen. (Fig’S. 1 and la are modified and corrected copies of the original figures in Bull. 141, U. S. Geol. Survey.) 2. Dorsal view of large individual from same locality. Fig. 3. Calyptraphorus trinodiferus Conrad 145 Dorsal view. 2 miles below Potomac Creek. Figs. 4, 4a. Calyptraphorus trinodiferus (?) Conrad var 146 4. Ventral view. 1 mile southeast of ISlason Springs. 4a. Dorsal view of the same specimen. Figs. 5, 6. Aporrhais potomacensis n. sp 146 5. Ventral view of imperfect individual. Digitations restored from original of Fig. 6. 1 mile northeast of Piscataway. 6. External view of labruni of large individual from same locality. MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XXV. MOLLUSCA — GASTROPODA. PLATE XXVI. PAGE Figs. 1-5. Turkitella mortoni Conrad 147 1. Ventral view of specimen. Potomac Creek, la. Dorsal view of same specimen. 2. More elong’ate specimen from same locality. 3. Specimen from same locality with stronger basal carina. 4. Internal cast. 5. Specimen showing- the strong basal carina of the variety postmortonl of Harris. Tinkers Creek. MARYLAND GEOLOGICAL SURVEY, EOCENE, PLATE XXVI MOLLUSCA GASTROPODA. PLATE XXVII. PAGE Fig’S. 1, la. Turritella iiumerosa Conrad 148 1. Ventral view. 1 mile southeast of Mason Springs. Figs. 2, 3. Turritella potomacensis n. sp 149 T3^pe specimens. Popes Creek. Fig. 4. Mesalia obruta (Conrad) 149 Popes Creek. Figs. 5, 5a, 6, 7. Vermetus sp 150 5. Small mass of tubes. 5a. End of same tube, enlarged. 6. Mass of tubes. Piscataway Creek. U. S. National Museum. 7. Short fragment of tube from same specimen, enlarged. 3T9 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XXVII. 5 6 MOLLUSCA GASTROPODA. PLATE XXVIII. PAGE Fig-. 1. Xatica cliftonensis Clark 150 Ventral view of type sj)ecimen. Clifton Beaeli. Figs. 2, 2a, 3. Lunatia makylandica Conrad 151 Figs. 4, 5. CAr.YPTEAEA APERTA (Solancler) 152 4. Dorsal view of specimen. 1 mile southeast of Mason Springs. 5. Cast of large individual. Figs. 6, 6a. Litiopa marylandica n. sp 152 G. Dorsal view of type specimen. 2 miles below Potomac Creek. Figs. 7, 7a. Solarium sp 153 7. Cast, as seen from above. Aquia Creek. 7a. Same specimen as seen from the side. Figs. 8, 8a, 9, 9a. Sc ALA virgintana Clark 153 8. Ventral view of type specimen. Ac|uia Creek. U. S. National Museum. 8a. Dorsal \iew of same specimen. 9. Ventral view of sjiecimen. Potomac Creek. Acad. Nat. Sci. Phila. 9a. Dorsal view of the same specimen. Fig. 10. SCALA POTOMACENSIS n. sp 154 Type specimen. 2 miles below Potomac Creek. Pig. 11. Sc ALA SESSILIS Conrad 154 2 miles below Potomac Creek. Fig. 12. ScALA CARUSTATA Lea 154 2 miles below Potomac Creek. 280 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XXVIII. MOLLUSCA GASTROPODA. PLATE XXIX. *PAGE Fig-. 1. TuRBONILLA POTOMACENiSIS n. sp 155 2 miles below Potomac Creek. Fig-. 2. Tuba marylandica n. sp 155 Mouth of Paspotansa Creek. Fig. 3. Odostomia trapaquara (Harris) 156 Potomac Creek. Fig. 4. Niso UMBiLiCATA (Lea) 156 Potomac Creek. Fig. 5. Gibbpla glandula (Conrad) 157 Potomac Creek. Figs. 6, 6a. Fissuridea marlboroensis n. sp 158 6. Lateral view of type specimen. Upper Marlboro. 6a. Dorsal view of same specimen. Fig. 7. Dentalium minutistriatum Gabb 158 Popes Creek. Fig. 8. Deintalium mississippiensis Conrad 159 Upper Marlboro. Fig. 9. Cadulus abruptus Meyer and Aldrich 159 Woodstock. 281 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XXIX. MOLLUSCA — -GASTROPODA AND SCAPHOPODA. PLATE XXX. PAGE Figs. 1, la. Teredo vieginiana (?) Clark 160 1. Lateral view enlarged as indicated, la. End view of same specimen. Figs. 2,- 2a, 3. Teredo vieginiana Clark 160 2. ETiteral view of small fragment of tube. Woodstock. 2a. End view of same specimen. 3. Lateral view of another fragment. Woodstock. Figs. 4, 4a, 4b. Phenacomya petrosa (Conrad) 161 4. Dorsal view of cast. Fort Washington. 4a. Same specimen as seen from the left. 4b. Same specimen as seen from the right. Fig. 5. Gastrociiaena sp 161 Cast of tube. Aqnia Creek. 383 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XXX. MOLLUSCA PELECYPODA. PLATE XXXI. PAGE Figs. 1-5. Panopea elongata Conrad 162 1. Left aspect of cast. Fort Washington. 2. Left valve. Aquia Creek. 2a. Surface of same specimen. X 17 3. Light valve of Fig. 1. 4. Left valve. Fort Washington. 5. Light valve. Fort Washington. 283 MARYLAND GEOLOGICAL SURVEY, EOCENE, PLATE XXXI. MOLLUSCA PELECYPODA. PLATE XXXII. Figs. 1, la, 2, 2a, 2b, Corbula subengonata Dali 1. Exterior of right valve. Poises Creek, la. Interior of same specimen. 2. Interior of left valve. Popes Creek. 2a. Exterior of same specimen. 2b. Hinge of same specimen, enlarged. Figs. 3, 3a, 4, 4a, 5, 5a, 6, 6a. Corbula alurichi Meyer 3. Exterior of right valve. Evergreen, Va. 3a. Interior of same specimen. 4. Interior of left valve. Evergreen, Va. 4a. Exterior of same specimen. 5. Exterior of right valve. Evergreen, Va. 5a. Interior of same specimen. 6. Interior of yonng left valve. Evergreen, Va. 6a. Exterior of same specimen. Figs. 7, 7a, 8, 8a, 8b. Corbula oniscus Conrad 7. Interior of right valve. Evergreen, Va. 7a, Exterior of same specimen. 8. Dorsal view of specimen. Evergreen, Va. 8a, Interior of right valve of same individual. 8b. Exterior of same valve. MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XXXII. MOLLUSCA PELECYPODA. PLATE XXXIII. PAGE Fig. 1. SOLEN LISBONENSIS (?) Alclrich 165 Fragment of left valve. ^ mile below Chapel Point. Figs. 2, 2a. Tellina williamsi Clark 167 2. Exterior of left valve. Potomac Creek. 2a. Interior of same specimen. Fig. 3. Tellina vieginiana Clark 166 Exterior of left valve. Hanoverville, Va. Fig. 4. Mereteix lenis (Conrad) 168 Exterior of right valve. Woodstock. Figs. 5-9. Mereteix subimpressa Conrad 170 5. Exterior of right valve. Acad. Nat. Sci. Phila. 5a. Interior of same specimen. 6. Dorsal aspect of complete individnal. Acad. Nat. Sci. Phila. 7. Exterior of left valve. Same collection. 8. Exterior of right valve. 8a. Interior of same specimen. 9. Interior of left valve. 9a. Exterior of same specimen. 385 MARYLAND GEOLOGICAL SURVEY. eocene, plate XXXIIl- d MOLLUSCA — PELECYPODA. TLATE XXXiV. PAGK Figs. 1, la. Meretiux ovata var. ovata (Eogers) 168 1. Interior of right valve. West of Port Tobacco, X 2/7 la. Exterior of same specimen. Figs. 2-5. Meeethix 0Vx\ta var. pyga Conrad IGD 2. Exterior of right valve. 2a. Interior of same sj)ecimen. 3. Interior of left valve. 3a. Exterior of same si)eeimen. 4. Exterior of right valve. 5. Exterior of left valve of young individual. 386 MARYLAND GEOLOGICAL SURVEY EOCENE, PLATE XXXIV. MOLLUSCA PELECYPODA, PLATE XXXV. Figs, la-lg. Dosmiopsis lenticularis (Pogers) la. Interior of left valve. Glymont. lb. Interior of right valve. Same localit3\ l c. Exterior of Fig. la. l d. Exterior of Fig. lb. le. Dorsal aspect of comihete individnal. Same locality. l f. Interior of left valve. Same locality. l g. Interior of right valve. Same locality. PAGE 171 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XXXV. MOLLUSCA PELECYPODA. PLATE XXXVI. PAGl' Fig-s. 1-3. Pkotocaedia i.KNis ('onriid 172 1. Exterior of right valve. 1 mile southeast of Mason Sx^ring’s. la. Interior of same valve. 2. Interior of left valve. Pamnnkey Iviver, Va. Acad. Nat. Sci. Phila. 2a. Exterior of same valve. 3. Exterior of right valve from same locality and in same collection. Fig-. 4. Diplodonta MxVelboeoensis n. si) 173 Exterior of left valve. Upper Marlboro. X 7/4 Fig’S. 5, 5a, G, 7. Diplodonta hopkinsensis Clark 174 5. Extei-ior of left valve. Everg-reen, Va. 5a. Interior of same valve. 6. Exterior of right valve. vSame locality. 7. Hinge much eitlarged. MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XXXVI. MOLLUSCA PELECYPODA. PLATE XXXVII. Eig-s. 1, la. Lucina aquiana Clark 174 1. Exterior of right valve. Tyj)e specimen. Aquia Creek. U. S. Na- tional Museum, la. Interior of same valve. Figs. 2, 2a. Lucusta astaetiformis Aldrich 2. Interior of left valve. 1 mile southeast of Piscataway. 2a. Exterior of same valve. Figs. 3, 3a, 3b. Lucina dartoni Clark 3. Interior of right valve of the type specimen. Woodstock. 3a. Exterior of same valve. 3b. Exterior of left valve of same individual. Figs. 4-7. Lucina uhleri Clark 176 4. Exterior of right valve of type specimen. Woodstock. 5. Interior of right valve of siiecimen. 1 mile southeast of Mason Springs. 6. Interior of left valve. Same locality. 7. Exterior of left valve of tyjie specimen. Woodstock. Figs. 8, 8a, 9. Lucina whitei Clark 176 8. Exterior of right valve of type specimen. Woodstock. 8a. Interior of same specimen. 9. Exterior of left valve of duplicate type. Same locality. 389 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XXXVII. . MOLLUSCA PELECYPODA, PLATE XXXVill. PAGE Figs. 1, la. Venekioardia planicosta var. regia Conrad ITS 1. Exterior of right valve. Upper INIarlhoro. Acad. Nat. Sci. Phila. X 9/10 la. Interior of same valve. MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XXXVIII. MOLLUSCA PELECYPODA. PLATE XXXIX. Fig-s, 1, la. Venericardia planicosta var. regia Conrad 1. Exterior of left valve of individual fignired on Plate XXXVIll. X 9/10. la. Interior of same valve. PAGE 178 291 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XXXIX. MOLLUSCA — PELECYPODA. 178 Figs. 1, 2, 3. Venericardia planicosta var. regia Conrad 1. Anterior view of complete individual figured on Plates XXXVIII and XXXIX. Acad. Nat. Sci., Phila. 2. Exterior of left valve of very young- individual. 3. Exterior of riglit valve of young- individual. Figs. 4-6. Venericardia potapacoensis n. sp 179 4. Exterior of left valve of type specimen. West of Port Tobacco. 5. Exterior of left valve. 5a. Interior of same specimen. 6. Exterior of right valve. 6a. Interior of same specimen. Figures 5 and 6 are from specimens in the Philadelphia Acad- emy of Natural Sciences. The locality of these specimens is in doubt, but they represent that form of V. potapacoensis which occurs typically in the Woodstock substage. Figs. 7, 7a. Venericardia marylandica n. sp 179 7. Exterior of right valve of type specimen. 2y^ miles above Popes Creek. 7a. Interior of same specimen. MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XL. MOLLUSCA — PELECYPODA, PLATE XLI. Eig-s. 1-8. Ceassatellites alaeformis (Conrad) 1. Exterior of the right valve of the type specimen of C. decUvis Heilprin. Aqnia Creek. U. S. National Museum. (After Aldrich.) 2. Exterior of the left valve of the same. (After Aldrich.) 3. Exterior of right valve. Fort Washington. 3a. Interior of the same. 4. Interior of left valve. Fort Washington. 4a. Exterior of the same. 5. Exterior of left valve. 6. Exterior of left valve. Fort Washington. 6a. Interior of the same. 7. Interior of left valve. Fort Washington. 7a. Exterior of the same. 8. Exterior of right valve. Fort Washington. 8a. Interior of the same. PAGE 180 393 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XLI. MOLLUSCA PELECYPODA. PLATE XLII. PAGE Figs. 1, 2a, 2b. Ceassatellites aquiana (Clark) 181 1. Dorsal aspect of type specimen. Aquia Creek. 2a. Exterior of left valve of the same individual. 2b. Exterior of right valve of the same. Fig. 3. Ceassatellites alta (Conrad) 18S Exterior of specimen. Hardesty. Figs. 4, 4a. Ceassatellites sp 183 4. Exterior of right valve. Clifton Beach. 4a. Interior of the same. Fig. 5. Astaete maeylaxdica Clark 183 Exterior of left valve of type specimen. Upper Marlboro. 294 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XLII MOLLUSCA PELECYPODA PLATE XLIII. PAGE Fig-s. 1, la, 2, 2a. Coralliophaga (Oryctomya) bryani Clark 183 1. Exterior of right valve. 1 mile southeast of Mason Springs, la. Interior of the same specimen. 2. Exterior of right valve of the type specimen. Pomonkey Neck. U. S. National Museum. 2a. Interior of the same specimen. Fig. 3. Pholadomya marylandica Conrad 184 Exterior of left valve. Fort Washington. Acad. Nat. Sci. Phila. Figs. 4, 5, 5a. Modiolus alabamensts Aldrich 185 4. Exterior of right valve. Mouth of Paspotansa Creek. 5. Exterior of right valve. Potomac Creek. 5a. Exterior of left valve of same individual. Fig. 6. Modiolus marylandicus n. sp 186 Dorsal aspect of crushed specimen. Woodstock. Fig. 7. Litiiopiiaga marylandica n. sp 186 Exterior of left valve of type specimen. Clifton Beach. 395 MOLLUSCA PELECYPODA, PLATE XLIV. PAGE Fig-s. 1, la. Anomia mcgeei Clark 187 1. Exterior of left valve of type siDecimen. Hanover Co., Va. Acad. Nat. Sci. Phila. la. Interior of the same. Fig'S. 2, 2a, 3. Anomia marylandica n. sp 187 2. Exterior of left valve. Pojies Creek. 2a. Interior of the same. 3. Exterior of left valve. Same locality. Fig'S. 4, 5, 6. Pecten choctavensis Aldrich 188 4. Exterior of rig'ht valve. Popes Creek. The height of the orig'- inal is 13.5 mm. instead of 11 mm. as the line indicates. 5. Exterior of left valve. Popes Creek. 6. Exterior of left valve of smaller individual. Same locality. Figs. 7, 7a, 7b. Pecten dalli Clark 188 7. Exterior of right valve of type specimen. Potomac Creek. 7a. Hinge of the same. X 2 7b. Interior of the same. Figs. 8, 8a. Pecten johnsoni Clark 189 8. Exterior of left valve of type sjiecimen. Potomac Creek. 8a. Interior of the same. Figs. 9, 9a. Pecten sp 190 9. Interior of right valve. Potomac Creek. 9a. Exterior of the same. MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XLIV. MOLLUSCA PELECYPODA. PLATE XLV. PAGE OsTKEA coMPRESsmosTEA Say 190 Lower valve of larg-e individual. X % MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XLV. MOLLUSCA PELECYPODA, PLATE XLVI. PAGE Figs. 1, 2. OsTREA COMPRESSIROSTRA Say 190 1. Lateral view of specimen figured on Plate XLV. X 1 2a, 2b, 2c. Exteriors of young lower valves. 298 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XLVI. MOLLUSCA PELECYPODA, PLATE XLV:i. Fig’S. 1-4. OSTEEA COMPEESSIROSTRA Say 1. Exterior of lower valve, la. Interior of the same. Ih. Lateral aspeet of the same indiviclnal. 2 , 3, 4. Exteriors of young- upper valves. PAGE 190 299 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XLVIl. MOLLUSCA PELECYTODA. PLATE XLVIll. Figs, la, lb. OsTREA sellaeformis Conrad la. Interior of lower valve. Janies Eiver, Va. lb. Exterior of upper valve of same individual with lower valve i position. PAGE 192 800 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XLVIll. MOLLUSCA PELECYPODA, PLATE XLIX. Fig-s. la-ld. OsTEEA sellaefoemis Conrad la. Lateral view of specimen figured on Plate XL VIII. lb, Ic, Id. Exteriors of lower valves of young individuals. James River, Va. PAGE 192 301 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE XLIX. f MOLLUSCA — I'Er.ECYrODA. PLATE L. PAGE Fig-s. 1-5. OsTKEA (Grypiiaeostrea) vomer (Mort(Mi) 193 1. Exterior of lower valve. Glymont. la. Lateral aspect of the same. lb. Interior of the same. 2, 3. Exteriors of lower valves of yoniig individnals. 4. Exterior of iipj)er valve, with typical form and sculpture. Upper Marlboro, la. Interior of the same. 5. Exterior of lower valve, abnormally elong-ated and shallow. Clifton Beach. Figs. 6, 6a. Gryphaea vesicularis Lamarck 193 6. Exterior of lower valve. Clifton Beach. 6a. Exterior of nj)per valve of same individual, with lower valve in position. 302 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE L. MOLLUSCA PELECYPODA, PLATE LI. PAGE Fig-. 1. Ptekia limula (Conrad) 194 Exterior of left valve. Popes Creek. Fig-s. 2, 2a, 3, 3a, 4. Glycymeris iuoxeus (Conrad) 194 2. Interior of s^iecimen. LTpf>er klarlboro. Acad. Nat. Sci. Phila. 2a. Exterior of the same specimen. 3. Exterior of larg-er specimen from the same locality and col- lection. 3a. Interior of the same specimen. 4. Exterior of another specimen from Upper Marlboro. Fig'S. 5, 5a. Trigonoaeca decisa (Conrad) var 195 5. Interior of a right valve. Woodstock. 5a. Exterior of the same valve. MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE LI. MOLLUSCA PELECYPODA. PLATE LTI. PAGE Figs, la, lb. CucuLLAEA gigantea C'oiirad . , 196 la. Interior of left valve. I*otoniac Creek. lb. Exterior of same valve. 304 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE MOLLUSCA PELECYPOUA. PLATP] LTIl. Figs, la, lb. CucuLLAEA gioantea Conrad la. Interior of right valve of individual figured on Plate Lll. lb. Exterior of same valve. PAGE 196 305 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE Llll. MOLLUSCA PELECYPODA. PLATE LIV. 'ig-s. la, lb, Ic. CucuLLAEA GiGANTEA Coiirad la. Exterior of left valve of young’ of the fnut.srerm ty])e. Potomac Creek. lb. Interior of the same valve. l c. Dorsal aspect of larg’e cast. Fort Washington. PAGE 19G MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE LIV. MOLI.USCA PELECYPODA. PLATE LV. PAGE Fig-s. la, lb, Ic. Cucullaea gtgantea Conrad 196 la, lb. Diagrams showing’ transverse section of the individual tig’ured on Tdates Ltl and LI II. Ic. Lateral aspect of the individnnl figured on Plate LTV, Fig. Ic. 807 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE LV. PLATE LVI. PAGH Fig'S. 1-4. Leda impkoceba (Conrad) 199 1. Exterior of right valve. Po^Jes Creek. 2. Interior of right valve. Woodstock. 3. Interior of right valve. Popes Creek. 4. Exterior of right valve. Popes Creek. Figs. 5, 6, 7, 7a. Leda parva (Kogers) 197 5. Dorsal aspect of individual. Woodstock. 6. Exterior of right valve. Woodstock. 7. Interior of left valve. Woodstock. 7a. Exterior of same specimen. Figs. 8, 8a. Leda cultelliformis (Rogers) 198 8. Exterior of right valve. Woodstock. 8a. Interior of right valve. Woodstock. Figs. 9, 10. Leda potomacensis n. sp 200 9. Exterior of right valve. Port Royal, Va. 10. Exterior of left valve of young individual. Popes Creek. Fig. 11. Leda cliftonensis n. sp 201 Exterior of right valve. 2 miles below Potomac Creek. 308 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE LVI. I 11 MOLLUSCA PELECYPODA. PLATE LVII. PAGE Fig-s. 1, 2, 2a. Leda parilis (Conrad) 199 1. Exterior of left valve. Upper Marlboro. 2. Exterior of rig'ht valve. Same locality. 2a. Interior of same valve. Fig. 3. Leda parilis (Conrad) var 200 Exterior of left valve. Probably from Woodstock. Figs. 4, 4a, 5. Leda tysoni n. sp. 201 4. Interior of right valve. Woodstock. 4a. Exterior of same valve. 5. Exterior of smaller right valve. Woodstock. Fig. 6. Nucula ovula Lea 202 Exterior of left valve. Woodstock. Figs. 7, 7a, 8, 8a. Nucula potomacensis n. sp 202 7. Interior of left valve. Woodstock. 7a. Exterior of same valve. 8. Exterior of right valve. Woodstock. 8a. Interior of same valve. 309 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE LVIl. g MOLLUSCA PELECYPODA, PLATE LVIII. PAGE Figs. 1, la, lb, Ic. Platidia makylandica n. sjj 203 1. Exterior of ventral valve. Upper Marlboro. la. Interior of the same. lb. Exterior of dorsal valve of the same individual. l c. Interior of the same. Figs. 2, 3, 3a. Terebeatula haelani Morton 204 2. Interior of ventral valve. 3 miles west of Leeland. X 4/9 3. Exterior of ventral valve from the same locality. 3a. Dorsal asjject of the same individual. 310 MARYLAND GEOLOGICAL SURVEY I EOCENE, PLATE LVIll. I I 3 3a MOLLUSCOIDEA — BRACHIOPODA. PLATE LIX. PAGE Figs. 1 and 2. Fascipora subramosa n. sp 207 1. A fragment. Upper Marlboro. X 6 2. Surface of same, showing several covered apertures. X 20 Fig. 3. Discosparsa varians n. sp 205 3. Surface of a parasitic specimen, showing* one of its maculae. Uj)i)er Marlboro. X 12 Figs. 4-8. Cavaria dumosa n. sj) 208 4. Portion of a small but well j)reserved branch, showing two maculae, prominent zooecial mouths, and mesopores. When worn the walls are much thinner and the apertures corre- spondingly larger. X 9 5. Portion of the fractured end of a branch. X 20. 6. A branch broken longitudinally to show the central hollow and tubes bending outward from it. X 9 7. Surface of another specimen, showing portion of one of the large gonocysts in right half of figure and usual appearance of zooecia and mesof)ores in left half. It is to be observed that not only the zooecial tubes pass through the gonocyst but smaller accessory tubes, evidently different from the ordinarj^ mesopores, as well. (See also Fig. 8.) X 20 8. One of the large gonocysts broken so as to show the tubes i)ass- ing through it. X 20 The originals of Figs. 4-8 are all from Upper Marlboro. Figs. 9-12. Eeticulipora dichotoma Gabb and Horn 207 9. The broken end (transverse section) of a fragment. In the lower half the length of the tubes corresponds with the length of the branches, but in the ujiper part they turn gradually upward until their direction is nearly at right angles to the length. X 6 10. Upper and lower fourths of the same. X 20 11. I’ortion of one of the sides of a fragment. X 20 12. A broken gonocyst which was found over a j)revious smaller cyst which remains intact. X 20 Figured specimens all from Upf)er Marlboro. Figs. 13 and 14. Ceriopora micropora Goldfuss 210 13. A subglobular mass, showing the form usually characterizing this species. 2% miles above Popes Creek. X 6 14. Surface of the same. X 20 Figs. 15 and 16. Heteropora ? tecta n. sp 210 15. Upper portion of a zoarium. The terminal portions of the branch are covered uniformly with subangular mouths of tubes, while in the lower portion and in the axis of the main bifurcation, nearly all the mouths are covered with a finely punctate pellicle. The few apertures in the pelliculate parts are rounded. Upper Marlboro. X 6 16. Portion of the same. X 20 Pigs. 17 and 18. Lepralia subplana n. sp 219 17. Surface of a specimen preserving the front wall of only seven of the zooecia shown in the figure. Upper Marlboro. X 20 18. The edge of a broken specimen from the same locality, showing four layers of zooecia. X 20 311 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE LIX. ## »?!*•! MOLLUSCOIDEA BRYOZOA. PLATE LX. PAGE Fig'S. 1 and 2. Membranipora rimt^lata n. sp 211 1. Surface of a specimen of the small-celled variety of this species. Upper Marlboro. X 20 2. Surface of the type specimen. X 20 Figs. 3 and 4. INIembranipora spiculosa n. sp 212 3. Surface of a siDecimen, showing form and arrangement of zooecia and ovicells. Upper Marlboro. X 20 4. Several zooecia of same, more hig'hly magnified. Figs. 5 and 0 . JMembranipora angusta n. sp 213 5. Surface of a specimen, showing connecting pores and ovicells. Ux3per Marlboro. X 25 6. Portion of another and more worn specimen, without ovicells. X 20 Fig. 7. Biflustra torta Gabb and Horn 214 7. I’ortion of a fragment of the bifoliate zoarinm of this species. Ux)X)er ]\larlboro. X 20 Figs. 8 and 9. Eeptoflustrella heteropora Gabb and Horn 213 8. Surface of the Eocene form. Uj:)x:)er Marlboro. X 20 9. One zooecium of same more highly magnitied. Figs. 10 and 11. Esch^ra ?? digitata Alorton 216 10. Surface of a fragment of the Eocene form of this sxDecies. Upper ISlarlboro. X 20 11. Perfect zooecium of same more highly magnified to show the lunarium-like process of the lower border of the aperture. Figs. 12 and 13. Cribrilina modesta n. sp 218 12. Portion of the type sx3ecimen of this species. Upper Marlboro. X 20 13. One zooecium of same more highly magnitied. Fig. 14. Cribrilina crassula n. sp 218 14. Portion of the somewhat worn specimen described. Upper Marl- boro. X 20 Figs. 15 and 16. Lepralia labiosa n. sp 220 15. Surface of an average sx3ecimen. X 20 16. Two young zooecia, each with two avicularia and a semilnnate area in the upper xiortion of the apertural rim. X 20 Figs. 17 and 18. Mucronella aspera n. sp 221 17. Surface of a sxiecimen. Upper Marlboro. X 20 18. A few zooecia of another specimen. X 20 Figs. 19 and 20. Lunulites reversa n. sp 217 19. I’ortion of front surface of the specimen described. 2 miles below Potomac Creek. X 25 20. Portion of dorsal surface of same. X 20 313 MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE LX. MOLLUSCOIDEA — BRYOZOA. PLATE LXI. PAGE Fig. 1. Fragment of spatangoid pi^te 232 Evergreen, Va. X 5/3 Fig. 2. Echinoid spine 232 Potomac Creek. Figs. 3, 3a. Flabellum sp 222 3. Upright view of coralhim, height 12 mm. 1 mile southeast of I’iscataway. 3a. Calicnlar view, greater diameter of calice, 15.5 mm. Figs. 4, 4a, 4b. Turbinolia acuticostata Vaughan 223 4. Upright view of corn Hum, height 6.5 mm. Popes Creek. 4a. Calicular view, diameter of calice, 3 mm. 4b. Margins of the costa* of another specimen enlarged. Figs. 5 to 8. TROCHOcrATiiiJS clarkeanus Vaughan 225 5. Uiiright view of a sjiecimen, height 12.5 mm. 5a. Calicular view of the same, greater diameter of calice, 7.75 mm. 6. Upright view, height 10.5 mm. 7. Upright view of another specimen, height 10 mm. 8. Upright view of a fourth specimen, height 9.5 mm. Figs. 9, 9a, 9b. Paracyatiius marylandicus n. sp 226 9. Upright view of corallum, height 5 mm., 1 mile northeast of Piscataway. 9a. Costae enlarged. 9b. Calicular view, greater diameter of calice, 5.75 mm. Figs. 10, 11. Balanophyllia desmophyllitm M.-E. and H 227 10. Upright view, height 23 mm., 1 mile southeast of Mason Springs. 11. Uiiright view of another specimen, height 26 mm. Same locality. Figs. 12 to 14. Eupsammta elaborata (Conrad) 229 12, Upright view of a specimen, height 17.5 mm. 13, 13a. Conrad’s type (from Alabama), length of corallum, 13 mm.: greater diameter of calice, 12 mm. 14, 14a. An unusually slender specimen; height of corallum, 15.5 mm.; greater diameter of calice, 9.5 mm. Potomac Creek. Figs. 15, 15a, 15b. Eupsammia conradi Vaughan 231 Conrad’s type of TnrhhioUa pilcolus (not Turhinolia pileolus Eich- wald). Height of corallum, 11 mm.: greater diameter of calice, 13 mm. Acad. Nat. Sci. Phila. MARYLAND GEOLOGICAL SURVEY. EOCENE, PLATE LXI. ECIIINODERMATA AND COELENTERATA. T’LATE LXTT. PAGE Fig-. 1. Textularta gramen d'Orbigny 233 1 mile nortlieast of Piscataway. X 50 Fig. 2. Textularta sagittela Def ranee 234 Upper Marlboro. X 50 Fig. 3. Textularia surangueata d’Orbigny 234 Brooks Estate near Seat Pleasant. X 50 Fig. 4. Spiroplecta clarki Bagg 235 Type specimen. Woodstock. X 50 Fig. 5. XODOSARIA AFFTXIS (d’Orbigny) 236 Woodstock. X 10 Fig. G. Nodosaria bacillum Defrance 236 3 miles west of Leeland. X 10 Fig. 7. Nodosaria communis (d’Orbigny) 237 1 miles northeast of Piscataway. X 21 Fig. 8. Nodosaria consorbrina var. emagiata (Benss) 238 Upper Marlboro. X 10 Fig. 9. Nodosaria sandbergeri (Eenss) 238 Upper Marlboro. X 24 Fig. 10. Nodosaria obeiqua (Linne) 239 Upjier Marlboro. X 10 3U PROTOZOA FORAMINIFERA. PLATE LXIII. PAGE Fig. 1, Vaginulina legumex (Linne) 240 Prooks Estate near Seat ITeasant. X 50 Figs. 2, 3. ]\1 abginulina costata (Batsch) 240 2. Large individual from Ujjper Marlboro. X 24 3. Smaller individnal from same locality. X 50 Fig. 4. CniSTELLARiA GiBBA d’Orbigiiv 241 1 mile northeast of Piseataway. X 24 Fig. 5. CniSTELLABiA ROTATUEA (Laimirck) 242 1 mile southeast of Mason Springs. X 7 Fig. 6. Crtstellabia radiata (Bornemann) 243 Woodstock. X 24 Fig. 7. PoLYMORPinxA AUSTRIACA (d’Orbigiiy) 244 Woodstock. X 50 Figs. 8, 9. PoLYMORPiiiNA COMMUNIS (d’Orbigny) 244 8. Woodstock. X 50 9. Upper Marlboro. X 50 Fig. 10. POLYMORPIIINA c OMPRESSA d’ Orbigiiy 240 Woodstock. X 40 Fig. 11. POLYMORPIIINA ELEGAN^i issiMA Parker and Jones 247 Woodstock. X 50 Fig. 12. POLYMORPIIINA GIBBA (d’Orbigny) 248 Brooks Estate near Seat ITeasant. X 50 Fig. 13, POLYMORPIIINA LACTEA (Walker and Jacob) 248 Upper ?^IaiTboro. X 50 Pig, 14. POLYMORPIIINA PRAELONGA Tcrcpiem 249 Woodstock. X 32 Figs. 15, 16, IGa. Globigerina bulloides d’Orbigny 250 Well at Chesapeake Beach at 90-92 feet. X 50 315 PROTOZOA FORAMINIFERA. PLATE LXIV. Fig. 1. Discoebina bertheloti (cFOrbigny) Woodstock. X 62 Fig. 2. Discoebina turbo (d’Orbigny) Upper Marlboro. X 62 Fig. 3. Truncatulina lobatula (Walker and Jacob) Upper Marlboro. X 62 Fig. 4. Truncatulina ungeriana (d'Orbigny) Upper Marlboro. X 30 Fig. 5. Anomalina ammonoides (Eeuss) Upj)er Marlboro. X 62 Fig. 6. Anomalina geosserugosa (Giimbel) 1 mile northeast of Piscataway. X 62 Fig. 7. PULVINULINA EXIGNA Var. OBTUSA BniTows 1 mile northeast of Piscataway. X 62 Fig. 8. PULVINULINA sciiREiBERSii (d’Orbigny) Woodstock. X 62 Fig. 9. Nonionina aefinis Reuss Woodstock. X 62 Fig. 10. Ampiiistegina lessonii d’Orbigny Woodstock. X 25 Figs. 11, 11a, 11b. Carpolithus marylandicus n. sp 11. Longitudinal section, showing position and shape of seed cell. Popes Creek. lla. Entire fruit, side view. llb. Entire fruit, viewed at the apex. Figs. 12, 12a, 12b. Carpolithus marylandicus var. rugosus n. var 12. Longitudinal section, showing position and shaxie of seed cell. Pojies Creek. 12a. Entire fruit, side view. 12b. Entire fruit, viewed at the apex. PAGE 251 251 252 253 251 254 255 256 257 257 258 258 316 PROTOZOA— FORAMINIFER, AND PLANTAE. INDEX A. C. Academy of Natural Sciences, Phila- delphia, 17. Accumulation of deposits, conditions of, 90. Alabama, Claiborne beds of, 27. Aldrich, T. H., 31, 75, 77, 79. “ Alluvial deposits,” 25. Alluvial formation, 25. Annapolis, fossils from, 74, 76, 78, 80, 149, 178, 205. Appalachian Kegion, 21. Aquia Creek, section near, 68, 69. Aquia Creek, fossils from, 74, 76, 78, 80, 96, 98, 102, 104, 105, 107, 124, 133.^ 132, 138, 146, 148, 149, 151-154, 160- 162, 166, 172-174, 178, 181, 182, 186, 192, 193, 197, 201, 223, 225, 231. Aquia formation, 58, 85. Aquia formation, composition of, 59. Aquia formation, distribution of, 74, 80. Aquia formation, description of, 59. Aquia formation, fossils from, 58, 68, 69, 71, 72, 73, 74, 76, 78, 80. Aquia formation, relation of to Chickasawan, 87. Aquia stage, species of, 86, 87. Arundel formation, 45. Ashley, S. C., 101. Atlantic Coast Province, distribution of Eocene in, 75. B. Bagg, E. M., Jr., 16, 31, 93. Bailey, J. W., 31, 56. Bassler, Eay S., 31, 41, 121. Bells Landing substage, 37, 84. Bibbins, A., 30. Bognor rock, 92. Booth, I. C., 28, 32,. Bracheux sands, 37, 92. Broad Creek, section near, 73. Buhrstone, 37. Buena Vista, fossils from, 74, 76, 78, 80, 138. h Case, E. C., 16, 93. Calcaire Grossier, 91. Chapel Point, fossils from, 75, 77, 79, 81, 145, 152, 160, 164, 166, 169, 177, 179, 193, 201. Character of Eocene deposits, 52. Charles Branch, fossils from, 75, 77, 79, 81, 201, 203. Charles County, 102. Chesapeake Beach, fossils from well at, 75, 77, 79, 81, 160, 161, 166, 247, 251, 254, 256. Chesapeake group, 47. Chester Eiver, section on, 73. ChickasaAvan stage, 84, 87, 89. City Point, Va., 33, 34. Claiborne beds of Alabama, 27. Claibornian stage, 84. Clark, Wm. Bullock, 9, 21, 32, 93. Cleaveland, Parker, 25, 33. Clifton, fossils from, 74, 76, 80, 95-97, 100, 112, 123, 125, 138, 148, 149, 151, 152, 160-164, 166, 170, 172, 176, 181, 183, 185-187, 191, 194, 197, 198, 201. Coastal Plain, 21. Coastal Plain deposits, general rela- tions of, 44. Collington, fossils from, 74, 76, 78, 80, 149, 170, 178, 181. Columbia formation, 49. Commission, 5. Conditions of accumulation of Eo- cene deposits, 90. Conrad, T. A., 27, 28, 29, 33, 34, 35, 51, 91. Contents, 11. Cope, E. D., 111. Correlation of deposits, 82. Correlation of deposits with those of Europe, 91. Cretaceous, 75, 77, 79, 81. Cretaceous, description of, 45. Crownsville, fossils from, 74, 76, 78, 80, 138. 318 INDEX D. Dali, W. H., 17, 35, 83, 92, 166, 167, 197. Dana, James D., 35. Darton, N. H., 30, 35, 40, 49, 57. Delaware, Eocene of, 49. Depth of sedimentation, 57. Distribution of species in Aquia for- mation, 74, 76, 78, 80. Distribution of species in Eocene, 75, 77, 79, 81. Distribution of species in Xanjemoy formation, 75, 77, 79, 81. Distribution of species, 73. Distribution of strata, 49. Diicatel, J. T., 28, 36. E. Eastman, Charles E., 16, 93. Ehrenberg, C. G., 56. Eocene deposits, comiDosition of, 52. Eocene deposits correlated within Middle Atlantic Slope, 82. Eocene deposits, general character of, 23, 52. Eocene deposits, general distribution of, 75. Eocene deposits, origin of, 54. Eocene deposits, strike and dip of, 53. Eocene deposits, thickness of, 54, 90. Eocene foraminifera, 31. Eocene formations correlated with Gulf states, 83. Eocene, first use in America, 27. Eocene of Middle Atlantic Slope, de- scription of, 46. Eocene strata, distribution of, 49. Eolignitic, 37. European equivalents, 91. Evergreen, Va., fossils from, 174, 232. F. Faunal stages, table showing, 58. Featherstonhaugh, G. W., 36. Finch, John, 25, 36. Fireman, Peter, analyses by, 53. Fontaine, W. M., 36. Formations, table showing, 58. Formations and faunal stages, 58. Fort Washington, 27, 31* 33. Fort Washington, fossils from, 74, 76, 78, 80, 104-106, 138, 148, 149, 151, 152, 161, 162, 166, 167, 170, 172, 179, 181, 185, 186, 191, 192, 197. Fossils of Paspotansa substage, 63. Fossils of Piscataway substage, 61. Fossils of Potapaco substage, 65. Fossils of Woodstock substage, 66. Fredericktown, fossils from, 74, 76, 78, 80, 172, 178, 193, 197. G. General stratigraphic relations, 44. Geographical distribution of species, 73. Geological criteria, 89. Geological distribution of species, 73. Geological divisions, 15. Gilman, Daniel C., 5. Glymont, 61. Glymont, fossils from, 74, 76, 78, 80, 107, 148, 149, 151, 152, 162, 163, 165, 170, 172, 176, 181, 182, 186, 191, 193, 197. Glymont, section at, 68. Greensand, origin of, 55. Greggs Landing substage, 84. Grimesville, fossils from, 74, 76, 78, 80, 170, 172, 192. Gulf province, distribution in, 75. H. Hanover county, Va., fossils from, 188. Hardesty, fossils from, 74, 76, 78, 80. 141, 148, 151, 162, 170, 172, 178, 182, 191, 195, 197. Harris, G. D., 17, 30, 37, 75, 77, 79, 133, 166, 167, 197. Harrisons Landing, fossils from, 74, 76, 78, 80, 172. Hatchetigbee substage, 84. Hayden, H. H., 25, 37. Heilprin, A., 37, 91. Heinrich, O. J., 38. Hering, Joshua W., 5. Higgins, James, 30, 38. Hilgard, E. W., 48. Hills Bridge, fossils from, 75, 77, 79, 81, 160, 165, 194. Historical review, 24. Hollick, Arthur, 16, 93. Hotchkiss, Jed., 38. Hunter, H. C., 17. I. Illustrations, List of, 13. Introduction, 21. Iterson, F. von, 17. INDEX 319 J. Jacksonian, fossils from, 75, 77, 79, 81. Jacksonian stage, 84, 85. Jaekel, O., 104. James river, deposits of, 29. Johns Hopkins University, collections of, 17. Johnson, C. W., 17. K. Kalm, Peter, 24, 38. Ivoken, E., 114, 115. L. Lafayette formation, 47. La Plata, fossils from, 75, 77, 79, 81, 180. Lea, Henry C., 39. Lea, Isaac, 27, 39, 91. Leeland, fossils from, 74, 76, 78, 80, 181, 191, 197, 205, 237. Leidy, Joseph, 101. Letter of transmittal, 9. Lignitic of Gulf, 37. Liverpool Point, fossils from, 74, 76, 78, 80, 95, 300, 103, 104, 105-107, 132, 136, 148, 149, 151, 3 52, 160, 164, 170, 172, 176, 181, 182, 185, 192, 197, 201. London clay, 27, 33, 91. LovN'er Chickasawan stage, 85. Lower Chickasawan stage, fossils from, 75, 77, 79, 81. Lower Claibornian, 85. Lyell, Chas., 29, 39, 91. Lyons Creek, section near, 72. M. McConnell, J. C., 17. McGee, W J, 30, 40, 49. Maclure, William, 24, 39. Manasquan formation, 205. Marlboro clay, 65. Marlboro Point, fossils from, 226, 233. Marls, analyses of, 53. Marsh, O. C., 111. Marshall Hall, 162. Martin, George Curtis, 21, 93. Maryland, Eocene in, 50. Mason Springs, fossils from, 74, 76, 78, 80, 125-127, 129-131, 140, 144, 146, 148, 149, 151-153, 155, 161-163, 166, 170, 173, 176, 181, 184, 186, 191, 197, 229, 231, 237, 243. Matawan formation, 45. Mattawoman Creek, fossils from, 74, 76, 78, 80, 106, 172, 176, 181, 182, 191. Maury, M. F., 39. Meyer, O., 91. Middle Atlantic Slope, 21. Midwayan stage, 84, 85. Miller, S. A., 40. Monmouth formations, 45. Morton, S. G., 26, 27, 40. Mount Misery, deposits at, 52. Mullica Hill, N. J., 214, 215, 216. Murchison, K. I., 29, 41. Murray & Renard, 55. N. Xanafalia substage, 84. Xanjemoy Creek, 66. Xanjemoy Creek, fossils from, 75, 77, 79, 80, 125, 145, 160, 164, 165, 169, 179, 199, 203. Xanjemoy Creek, section near, 70. Xanjemoy formation, 47, 58, 69, 70, 71, 72, 85. Xanjemo}" formation described, 64. Xanjemoy formation, relations to Chickasawan, 89. X'anjemoy stage, species of, 87, 88. Xeocene deposits described, 47. Xew Jersey, greensands of, 28. Xickles, John M., 31, 41. Xoetling, F., 104. O. Origin of Eocene materials, 54. Ostrea sellaeformis zone, 83. Oxen, section at, 71. P. Paleontological criteria, 84. Pamunkey formation, 35, 57. Pamunkey Group, 58. Pamunkey river, Ya., 35. Pamunkey river, Va., fossils from, 232. Paspotansa Creek, fossils from, 74, 76, 78, 80, 141, 147, 149, 151, 155, 162, 170, 173, 178, 181, 186, 189, 191. 197. Paspotansa stage, 58, 69, 72, 73, 71, 75, 76, 77, 78, 79, 80, 81. Paspotansa stage described. 62. Paspotansa stage, distribution, 74, 80. Paspotansa stage, fossils of, 63. Patapsco formations, 45. 320 INDEX Patuxent formations, 45. Patuxent river, section on, 73. Piedmont Plateau, 21. Pierce, James, 26,^41. Pilsbry, H. A., 17. Pisgah, fossils from, 74, 76, 78, 80, 172, 191. Piscataway, 33, 34. Piscataway, fossils from, 75, 77, 79, 81, 124, 125, 126, 128, 131, 133, 135, 136, 147-149, 151, 157, 159-165, 169, 171- 173, 175, 176, 178, 180, 181, 185, 188, 191, 193, 195, 197, 201, 202, 223, 226, 227, 233, 242, 255, 256. Piscataway, section at, 72. Piscataway Creek, fossils from, 74, 76, 78, 80, 150. Piscataway stag-e, 58, 68, 69, 71, 73, 74, 75, 76, 77, 78, 79, 80, 81. Piscataway stage described, 60. Piscataway stage, distribution in, 74, 80. Piscataway stage, fossils of, 61. Pleistocene deposits described, 48. Pomonkey Neck, fossils from, 74, 76, 78, 80, 132, 133, 143, 184. Popes Creek, fossils from, 75, 77, 79, 81, 102, 106, 108, 115, 123, 128, 130, 131, 136, 138, 139, 142, 146, 149, 150, 152, 155, 159, 161, 163-166, 169, 171, 173, 175, 176, 177, 179, 180, 182, 185, 187, 188, 192, 194, 195, 197, 198, 199, 202, 203, 210, 225. Popes Creek, section near, 70, 71. Post Eocene, fossils from, 75, 77, 79, 81. Port Tobacco, 32, 66. Port Tobacco, fossils from, 75, 77, 79, 81, 115; 124, 125, 131, 145, 151, 152, 159, 160, 179, 193, 201. Potapaco stage, 58, 65, 69, 70, 72, 75, 77, 79, 81. Potapaco stage described, 65. Potapaco stage, distribution in, 75. Potapaco stage, fossils of, 65. Potomac Creek, 75. Potomac Creek, fossils from, 74, 75-80, 100, 124-126, 129, 131-134, 136, 137, 140, 141, 144, 146-148, 150-157, 162, 163, 166, 170, 172, 173, 176, 178-182, 186, 189-191, 193, 195, 197, 201, 218, 225, 226, 231, 232, 237. Potomac Creek, section near, 69, 70. Potomac Groui), 45. Potomac Elver section, 67. Potomac river, section on, 67. Preface, 15. Probst, J., 104. R. Eancocas formation, 45. Earitan formation, 45. Eeedy Eun, fossils from, 74, 76, 78, 80,. 170, 172, 182, 191. Eogers, H. D., 28, 42. Eogers, William B., 27, 28, 41, 42, 51. Eolph’s Landing, fossils from, 74, 76, 78, 80, 148, 150, 162, 173, 178, 181, 195, 197. Eolph’s Landing, sections near, 73. Euffin, Edmund, 42. S. Say, Thomas, 26, 42. Schuchert, Charles, 16, 204. Schopf, Johann David, 24, 42. Seat Pleasant, fossils from, 74, 76, 78, 80, 120, 148, 149, 162, 170, 172, 181- 183, 192, 235, 238, 240, 254. Seat Pleasant, section near, 71. Secondary formation, 25. Section at Glymont, 68. Section near Lyons Creek, 72. Sections near Potomac Creek, 69-70. Section of Potomac river, 67, 68. Section of western portion of bluif at Aquia Creek, 69. Sedimentation, depth of, 57. Severn river, fossils from, 74, 76, 78,. 80, 179, 191, 232. Severn river, section near, 13. Shark Eiver formation, 205. Shattuck, G. B., 30, 49. Silvester, E. W., 5. Smith, John Walter, 5. Southeast Creek, fossils from, 74, 76,. 78, 80, 188, 189. South Eiver, fossils from near, 74, 76,. 78, 80, 145, 148-150, 172, 173, 178, 179, 181, 183, 191-193, 195, 197, 200,. 202, 232. South Eiver, section at, 73. Species, distribution of, 73. Stratigraphical and paleontological characteristics, 57. Strike and dip of Eocene deposits, 53. Suessonian, 92. Swan Creek, fossils from, 74, 76, 78, 80, 191. INDEX 321 T. Table of correlation, 85. Table showing- formations and faunal stages, 58. Table showing geographical and geo- logical distribution of species, 73. Table showing local and general dis- tribution of Eocene species, 74. Timber Creek, N. J., 208, 214,215,216,219. Tertiary formations, 22, 25. Thanet sands, 37, 92. Thickness of Eocene deposits, 54. Thrift, fossils from, 75, 77, 79, 81, 168, 197. Thrift, section near, 72. Tinkers Creek, fossils from, 74, 76, 78, 80, 148, 149, 162, 191. Transgression of Eocene deposits, 83. Transmittal, letter of, 9. Tuomey, M., 43, 123. Turritella rock, 64. Tyson, Philip T., 30, 43. U. Uhler, P. R., 30, 43. Ulrich, E. O., 16, 81, 93. U. S. Geological Survey, 17. U. S. National Museum, 17. Upper Chickasawan, 85. Upper Chickasawan, fossils from, 75, 77, 79, 81. Upper Claibornian, 85. Upper Marlboro, 31, 32, 34. Upper Marlboro, fossils from, 74-81, 117, 118, 120, 121, 124, 136, 140, 143, 145, 148-152, 155, 157-162, 164, 165, 169-176, 178, 180, 181, 183, 186, 188, 189, 191-195, 197, 199, 200, 202, 203, 206-208, 210-216, 218-222, 231-234, 237-239, 241-243, 249, 252-254. Upper Marlboro, section near, 72. V. Van Rensselaer, J. 26, 43. Vannxem, Lardner, 26. Vaughan, T. Wayland, 16, 43, 81, 93. Vincentown, N. J., 121, 206, 208, 209, 212, 214, 215, 216, 220, 222. Virginia, Eocene of, 51. W. Wades Bay, fossils from, 74, 76, 78, 80, 181, 186, 191. Washington, D. C., 35. Washington, fossils from near, 163. Willis, Bailey, 40. Williams, G. H., 40. Winchester, fossils from, 74, 76, 78, 80, 162. Woods Blnlf, Ala., 227 Woods Blulf substage, 84, 223. Woodstock, fossils from, 75, 77, 79, 81, 100, 105, 106, 109, 115, 122, 124, 125, 131, 133, 135, 136, 143, 150-152, 160, 163-166, 168, 171, 173, 175-177, 179, 184-187, 189, 192, 195-199, 201-203, 223, 236, 237, 243, 244, 246, 247, 249, 251, 253, 256-258. Woodstock, section at, 70. Woodstock stage, 58, 66, 70, 71, 75, 77, 79, 81. Woodstock stage described, 66. Woodstock stage, distribution of spe- cies from, 75, 77, 79, 81. Woodstock stage, fossils of, 66. Woodstock, Va., 31. Woodward, A. S., 98, 101. Woodward, Smith, 104. Wyman, Jeffries, 111, 112, 115. PALEONTOLOGICAL INDEX A. Actaeonidae, 123. Actinopterygii, 110. Acteon metanellus, 156. Aetobatis, 101. Aetobatis arcuatus, 74, 75, 102, 265. Aetobatis profundus, 102. Amphistegina lessonii, 67, 80, 81, 257, 316. Angelas, 166. Anomalina ammonoides, 63, 80, 81, 255, 316. Anomalina grosserugosa, 63, 80, 81, 25//, 316. Anomalodesmacea, 184. Anomia marylandica, 78, 79, 187, 295. Anomia mcg’eei, 187, 295. Anomia rufdni, 187. Anomiidae, 187. Anthozoa, 222. Aporrhaidae, 146. Aporrhais potomacensis, 63, 76, 77, U6, 277. Area onochela, 196. Area rogersi, 196. Areidae, 194. Artemis lentieularis, 171. Arthropoda, 74, 75, 116. Aspidobranehiata, 157. Astarte marylandiea, 63, 72, 78, 79, 183, 294. Astartidae, 183. Asterospondyli, 102. Athleta tuomeyi, 130. Avieula limula, 194. B. Bairdiidae, 116. Balanophyllia desmophyllum, 63, 80, 81, 85, 86, 227, 313. Berenieea, 206, 208. Bierisina gaudryana, 207, 208. Biflustra disjuneta, 212. Biflustra torta, 63, 80, 81, 2Z//, 312. Braehiopoda, 78, 79, 203. Bryozoa, 78, 79, 80, 81, 205. Bueeinidae, 3 36. Bj^ssomya petrieoloides, 186. B3^thoeypris j)arilis, 63, 74, 75, 117, 268. Bythoeypris subaequata, 63, 74, 116, 117, 268. C. Cadulus abruptus, 59, 66, 76, 77, 85, 86, 87, 88, 89, 159, 281. Cadulus bellulus, 159. Cadulus subeoaretatus, 160. Calliostoma sp., 63, 76, 77, 157. Calyptraea aperta, 59, 76, 77, 85, 86, 88, 89, 152, 280. Calj^ptraea aperta, 152. Calyptraea troehiformis, 152. Calj^ptraphorus jaeksoni, 63, 72, 76, 77, "755, 277. Calj'ptraphorus trinodiferus, 59, 65, 76, 77, 85, 86, 88, lJf5, 277. Cal^'ptraphorus trinodiferus (?) var., "76, 74, 11,6. Calj^ptraphorus velatus, 146. CaB^ptrophorus. See Calyptraphorus. Caneellaria graeiloides, 128. Caneellaria graeiloides var., 63, 74, 75, 85, 86, 128, 273. Caneellaria (Narona) potomaeensis, 63, 74, 75, 129, 273. Caneellaria parva, 129. Caneellaria ulmula, 129. Caneellaria sp., 63, 74, 75, 129, 273. Caneellaridae, 128. Caneroidea, 116. Capulidae, 152. Careharias, 109. Carehariidae, 108. Careharodon, 107. Careharodon aeutidens, 108. Careharodon angustidens, 108. Careharodon aurieulatus, 66, 74, 108. Careharodon eontortidens, 108. Careharodon erassidens, 108. Careharodon reetus, 108. 324 PALEONTOLOGICAL INDEX Cardiidae, 172. Cardita planicosta, 178, Carditidae, 172, 177. Cardium (Protocardia) lenis, 172, 173. Cardium nicolletti, 172. Caricella pyruloides (?), 60, 74, 75, 85, 86, ISl, 273. Caricella, 131. Caricella sp., 62, 131. Carpolithus marylandicus, 67, 80, 81, 258, 316. Carpolithus marylandicus var. I'ug'o- sus, 67, 80, 81, 258, 316. Caryophyllidae, 225. Cassididae, 144. Cassidaria brevidentata, 144. Cavaria dumosa, 63, 78, 79, 208, 311. Cavaria ramosa, 209. Cephalopoda, 74, 75, 122. Ceriopora micropora, 65, 80, 81, 210, 311. Cerioporidae, 208. Cestraciontidae, 102. Cheloniidae, 97, Chilostomata, 211. Chrysodomus engonatus, 63, 76, 77, 85, 86, IJ/O, 274. Cidaridae, 232. Cidaroida, 232. Cl 3 ^donautilidae, 122. Coelenterata, 80, 81, 222. Compressidens, 159. Coprolites, 96, 115, 262. Coralliophaga bryani, 63, 78, 79, 183. Coralliophaga (Oryctomya) bryani, 183, 295. Corbula alabamiensis, 163. Corbula aldrichi, 76, 77, 85, 86, 88, 163, 284. Corbula nasuta, 163. Corbula oniscus, 59, 67, 70, 76, 77, 85, 87, 88, 89, 164, 284. Corbula (Aloidis) oniscus, 164. Corbula sp., 71. Corbulidae, 163. Corbula subengonata, 59, 67, 71, 76, 77, 85, 86, 87, 163, 284. Crassatella alaeformis, 180. Crassatella alta, 182. Crassatella capri-cranium, 180. Crassatella declivis, 180. Crassatella palmula, 180. Crassatella protexta, 180. Crassatellites alaeformis, 60, 61, 64, 68, 69, 71, 72, 73, 78, 79, 180, 182, 183, 293. Crassatellites alta, 63, 78, 79, 182, 294. Crassatellites aquiana, 60, 61, 78, 79, 181, 294. Crassatellites palmula, 181. Crassatellites sp., 78, 79, 183, 294. Crassatellitidae, 180. Cribrilina crassula, 63, 80, 81, 218, 312. Cribrilina modesta, 63, 80, 81, 218, 312. Cribrilinidae, 218. Cristellaria acutauricularis, 241. Cristellaria crepidula, 242. Cristellaria cultrata, 243. Cristellaria excisa, 241. Cristellaria gibba, 63, 80, 81, 241, 315. Cristellaria pulchella, 241. Cristellaria radiata, 66, 80, 81, 243, 315. Cristellaria rotulata, 63, 80, 81, 242, 315. Cristellariae, 240. Crocodilia, 95. Crocodilidae, 95. Crustacea, 116. Cryptodira, 97. Cucullaea gigantea, 59, 61, 64, 69, 71, 72, 73, 78, 79, 85, 86, 87, 88, 196, 304, 305, 306, 307. Cucullaea gigantea var., 196. Cucullaea onochela, 196. Cucullaea rogersiana, 196. Cucullaea transversa, 196, 197. Cyclostomata, 205. Cylichna aldrichi, 125. Cylichna venusta, 59, 70, 74, 75, 124, 271. Cypraea smithii, 65, 76, 77, 85, 88, 144, 276. Cypraeidae, 144. Cythere angusticostata, 121. Cythere desha^^esiana, 120. Cythere edwardsi, 121. Cythere hebertiana, 120. Cythere macropora, 121. Cjdhere marjdandica, 60, 74, 75, 119, 268. Cjdhere punctata, 120. Cythere thierensiana, 120. Cjdhere triangularis, 119. ’ Cythere trigonula, 119. Cjdherea lenis, 168. Cj'therea lenticularis, 171. Cytherea liciata, 168. PALEOXTOLOGICAL INDEX 325 Cj'therea ovata, 168. Cytherea pyg’a, 169. Cytherea subimpressa, 170. O^’tliereis bassleri, 63, 71, 75, 120, 268. Cytheridae, 119. Cytheridea debilis, 122. Cytheridea intermedia, 122. Cytheridea miilleri, 122. Cytherella compressa, 116. Cytherella londinensis, 118. Cytherella marlboroensis, 63, 74, 75, 111, 118, 268. Cytherella ovata, 118. C^'therella siibmarginata, 63, 74, 75, 118, 268. Cytherellidae, 117. Cytheridea perarcuata, 74, 75, 121, 268. D. Decapoda, 116. Dentaliidae, 158. Dentalina affinis, 236. Dentalina badenensis, 237. Dentalina communis, 237. Dentalina consobrina var. emaciata, 238. Dentalina inornata, 237. Dentalina legnmen, 237. Dentalina sandbergeri, 238. Dentalina subarcuata, 237. Dentalium minutistriatum, 67, 76, 77, 158, 281. Dentalium mississippiensis, 59, 76, 77, 159, 281. Dentalium thalloides, 159. Diadematidae, 232. Diadematoida, 232. Dione liciata, 168. Dione ovata, 168. Dione pyga, 170. Diplodonta hopkinsensis, 173, 1V^, 288. Diplodonta marlboroensis, 63, 72, 78, 79, 113, 288. Diplodonta ungulifera, 173. Diplodontidae, 173. Discorbina bertheloti, 67, 80, 81, 251, 316. Discorbina turbo, 63, 80, 81, 251, 316. Discosparsa varians, 63, 78, 79, 205, 311. Doliidae, 141. Dosinia lenticularis, 171. Dosiniopsis lenticularis, 61, 68, 69, 71, 72, 78, 79, 85, 86, 111, 287. Dosiniopsis meekii, 171. E. Echinodermata, 232. Echinoidea, 232. Egeria rotunda, 173. Elasmobranchii, 98. Ensuchia, 95. .Escharidae, 219. Eschara digitata, 80, 81, 216, 312. Escharipora, 218. Escharipora immersa, 219. Escharipora incrassata, 219. Escharifora typica, 222. Euclastes (?) sp., 61, 74, 75, 91, 262. Eulimidae, 156. Eupsammia conradi, 231, 313. Eupsammia elaborata, 60, 62, 80, 81, 85, 86, 229, 313. Eupsammia (?) pileolus, 231. F. Fascipora pavonina, 207. Eascipora subramosa, 63, 78, 79, 201, 311. Fasciporidae, 207. Eissurellidae, 158. Fissuridea marlboroensis, 63, 72, 76, 77, 158, 281. Flabellum cuneiforme var. pachyphyl- lum, 223. Flabellum cuneiforme var. wailesi, 223. Flabellum johnsoni, 223. Flabellum sp., 80, 81, 222, 313. Foraminifera, 233. Fulgur argutus, 142. Fulguroficus argutus, 76, 77, 142, 276. Fulguroficus triserialis, 142, 143. Fusoficula- juvenis, 63, 76, 77, 85, 86, 143, 276. Fusidae, 133. Fusus (Hemifusus ?) engonatus, 140. Fusus (?), 134. Fusus (?) interstriatus, 74, 75, 85, 87, 88, 135, 273. Fusus (Levifusus) trabeatus, 139. Fusus (Strepsidura) perlatus, 136. Fusus (Strepsidura) siibscalarinus, 136. Fusus (?) subtenuis, 63, 74, 75, 85, 86, 134, 274. 326 PALEONTOLOGICAL INDEX Fusus trabeatus, 138. Fusus trabeatus (?) var., 76, 77, 139. G. Galeocerdo, 109. Galeocerdo latidens, 66, 74, 75, 109, 266. Galeocerdo minor, 109. Gastrochaena sp., 60, 76, 77, 161, 282. Gastrochaenidae, 161. Gastropoda, 74, 75, 76, 77, 123. Gibbiila glandula, 60, 72, 76, 77, 151, 281. Globiilina g-ibba, 248. Globigerina bulloides, 67, 80, 81, 250, 315. Globigerinidae, 250. Glycymeris elong'ata, 162. Glycymeris idoneus, 67, 70, 72, 73, 78, 79, 85, 86, 88, 191^ 302. Gryphaea eversa, 193. Gryphaea vesicularis, 61, 19S, 302. Gryphaea vomer, 193. Gryphaeostrea, 193. Grj^phaeostrea vomer, 59, 72, 193. Guttulina austriaca, 244. Guttulina communis, 244. Guttulina nitida, 244. Gymnog’lossa, 155. H. Hexacoralla, 222. Hercoglossa (Eiiclimatoceras) ulrichi, 123. Hercoglossa tuomeyi, 71, 74, 75, 122, 268, 269, 270. Heteropora (?) tecta, 63, 80, 81, 210, 311. Heteropora (Multicrescis) parvicella, 209. I. Idmoniidae, 207. Ischyrhiza (?) radiata, 112. L. Lagenidae, 236. Lamna, 103, 106. Lamna acuminata, 106. Lamna clavata, 105. Lamna compressa, 105. Lamna compressa (pars), 110. Lamna cuspidata, 105. Lamna elegans, 104, 105. Lamna (?) obliqua, 106. Lamnidae, 108. Latiarca idonea, 196. Latiarca onochela, 196. Latiarca transversa, 196. Latiarca gigantea, 196. Latirus marylandicus, 63, 74, 75, 133, 273. Leda (Adrana) cultelliformis, 198. Leda cliftonensis, 60, 78, 79, 200, 201, 308. Leda cultelliformis, 67, 70, 78, 79, 198, 308. Leda improcera, 64, 67, 78, 79, 199, 200, 308. Leda parilis, 72, 78, 79, 199, 309. Leda parilis var., 66, 78, 79, 200, 309. Leda parva, 67, 78, 79, 85, 86, 88, 191, 308. Leda pharcida, 201. Leda potomacensis, 64, 78, 79, 85, 88, 200, 308. Leda j)rotexta, 200, 201. Leda tysoni, 64, 78, 79, 201, 309. Ledidae, 199. Lenticulites rotulata, 242. Leimalia labiosa, 63, 80, 81, 220, 312. Lepralia subplana, 63, 80, 81, 219, 311. Levifusus trabeatus (?), 66, 76, 77, 138. Levifusus trabeatus (?) var., 66, 76, 77, 85, 88, 89, 139, 275. Limopsidae, 195. Limopsis decisus, 195. Litiopa marylandica, 76, 77, 152, 280. Lithophaga marylandica, 61, 78, 79, 186, 295. Littorinidae, 152. Lucina aquiana, 60, 72, 78, 79, 85, 86, llJf, 289. Lucina astartiformis, 65, 67, 78, 79, 85, 88, 115, 289. Lucina claibornensis, 177. Lucina dartoni, 64, 67, 78, 79, 115, 289. Lucina greggi, 174. Lucina sp., 78, 79, 111. Lucina uhleri, 59, 67, 78, 79, 85, 87, 88, 116, 289. Lucina ulrichi, 176. Lucina whitei, 64, 67, 78, 79, 116, 289. Lucinidae, 174. Lunatia eminula, 151. Lunatia marylandica, 59, 76, 77, 85, 86, 88, 89, 151, 280. Lunulites patelliformis, 217. PALEONTOLOGICAL INDEX 327 Lnnulites regularis, 217. Luniilites reversa, 63, 80, 81, 211, 312. Lunulites semilunaris, 217. M. Malacostraca, 116. Mangilia (Pleurotomella) bellistriata 74, 75, 128, 272. Marginulina, 240. Marg’inulina costata, 63, 80, 81, 2'fO, 315. Melong'ena (?) potomacensis, 63, 74, 75, 136, 274. Melong-ena subcarinata, 137. Membranipora angusta, 63, 80, 81, 213, 312. Membranipora lineata, 213. Membranipora perampla, 212. Membranipora rimulata, 63, 80, 81, 211, 312. Membranipora spiculosa, 63, 80, 81, 212, 214, 215, 312. ^tembraniporidae, 211. Meretrix lenis, 67, 76, 77, 168, 285. Meretrix liceata, 168. Meretrix nuttalliopsis, 169. Meretrix ovata, 168. Meretrix ovata var. ovata, 64, 65, 76, 77, 168, 286. Meretrix ovata var. pyga, 60, 61, 68, 69, 71, 72, 73, 78, 79, 85, 88, 169, 286. Meretrix pyga, 170. Meretrix subimpressa, 67, 70, 71, 78, 79, 85, 88, 110, 286. Mesalia obruta, 70, 71, 72, 76, 77, 85, 87, 88, Ui9, 279. Metula marylandica, 63, 76, 77, 139, 275. Microporidae, 216. Mitra marjdandica, 63, 74, 75, 132, 273. Mitra pomonkensis, 63, 74, 75, 132, 273. Mitra potomacensis, 70, 71, 74, 75, 133, 273. Mitra sp., 132. Mitsikurina, 1C3. Modiola alabamensis, 185. Modiola potomacensis, 185. Modiolus alabamensis, 59, 78, 79, 85, 87, 88, 185, 295. ^Modiolus marylandicus, 67, 71, 78, 79, 186, 295. Modiolus (Brachydontes) potomac- ensis, 185. Molluscoidea, 78, 79, 80, 81, 203. Mollusca, 74, 75, 76, 77, 78, 79, 122. Monodonta glandula, 157. Morio brevidentata, 63, 76, 77, 85, 86, lU, 276. Mucronella aspera, 63, 80, 81, 221, 312. Multicrescis parvicella, 259. Muricidea, 135. Myliobatis, 98. Myliobatis copeanus, 59, 74, 75, 99, 264, 265. Myliobatis holmesii, 100. Mjdiobatis magister, 100, 264, 265. Myliobatis pacbyodon, 99. Myliobatis pentoni, 100. Myliobatis sp., 101, 265. Myliobatidae, 98. Mytilidae, 185. N. Narona, 129. Naticidae, 150. Natica cliftonensis, 76, 77, 150, 280. Natica eminula var., 151. ISTautiloidea, 122. Nautilus (Ortlioceras) costatus, 240. Nautilus legumen, 240. Nautilus lobatulus, 252. Nautilus obliquus, 239. Nautilus sp., 122. Niso umbilicata, 63, 76, 77, 85, 86, 156, 281. Nodosaria affinis, 66, 80, 81, 236, 314. Nodosaria bacillum, 59, 80, 81, 236, 314. Nodosaria communis, 60, 80, 81, 231, 314. Nodosaria consorbrina v. emaciata, 63, 80, 81, 238, 314. Nodosaria obliqua, 63, 80, 81, 239, 314. Nodosaria sandbergeri, 63, 80, 81, 238, 314. Nodosaridae, 236. Noetia pulchra, 195. Nonionina affinis, 67, 80, 81, 251, 316. Nonionina punctata, 257. Nucula capsiopsis, 201. Nuciila cultelliformis, 198. Nucula improcera, 199. Nucula magnifica, 2f,2. Nucula ovula, 72, 78, 79, 85, 86, 202, 309. Nucula parilis, 199. Nucula parva, 197. Nucula potomacensis, 64, 67, 78, 79. 202, 309. 328 PALEONTOLOGICAL INDEX Niiculana cultelliformis, 198. Nuciilana improcera, 199. Nuciilana parva, 197. Nuculana protexta, 200, 201. Niiculidae, 202. O. Odontaspis, 103 , 106. Odontaspis cuspidata, 59, 71, 75, 105 , 266. Odontaspis eleg-ans, 61, 74, 75, 105 , 266. Odontaspis hopei, 105. Odontaspis macrota, 61, 74, 75, 104, 105 , 266. Odostomia insig’nifica, 156. Odostomia trapaqiiara, 63, 76, 77, 85, 86, 87, 156 , 281. Olividae, 130. Olivnla sp., 66, 74, 75, 130 . Olivula staminea, 130. Onychocella, 216. Opisthobranchiata, 123. Orthochaenites, 122. Oryctomya, 183. Osteodes elaborata, 229. Ostrea bellovacina, 190. Ostrea compressirostra, 60, 61, 64, 66, 69, 71, 72, 73, 78, 79, 85, 86, 190 , 191, 192, 297, 298. Ostrea compressirostra var. alepido- ta, 61, 62, 78, 79, 191 . Ostrea (Gryphaeostrea) subeversa, 193. Ostrea (Gryphaeostrea) vomer, 59, 78, 79, 85, 87, 89, 193 , 302. Ostrea sellaeformis, 64, 67, 70, 78, 79, 83, 85, 88, 89, 191, 192 , 300, 301. Ostrea sinuosa, 190. Ostrea sp., 193. Ostrea subeversa, 193. Ostracoda, 74, 75, 116. Ostreidae, 190. Otodns macrotus, 105. Otodns obliquus, 61, 74, 75, 106 , 267. Otolites, 113 , 264. Oxyrhina, 106. P. Panopea elongata, 60, 69, 72, 73, 76, 77, 162 , 282. Papillina staminea var., 137. Paracyathus alternatns, 227. Parac 3 mthus (?) clarkeanus, 225. Paraej'athus granulosus, 227. Parac^'athus marylandicus, 63, 80, 81, 226 , 313. Parallelodontidae, 196. Pasithea umbilicata, 156. Pavolunulites elegans, 217. Pecten calvatus, 189. Pecten clioctavensis, 59,’ 78, 79, 85, 87, 88, 188 , 189, 296. Pecten dalli, 67, 70, 78, 79, 85, 87, 89, 188 , 296. Pecten (Pseudamusium) frontalis, 188. Pecten greggi, 189. Pecten johnsoni, 78, 79, 85, 86, 88, 189 , 190, 296. Pecten rogersi, 188. Pecten sp., 63, 78, 79, 190 , 296. Pecten w^ahtubbeanus, 190. Pectinidae, 188. Pectunculus decisus, 195. Pectunculus idoneus, 194. Pelecypoda, 76, 77, 78, 79, 160. Periploma (?) sp., 65, 78, 79, 185 . Periidomidae, 184. Peronidia, 167. Plienaeom^'a petrosa, 62, 76, 77, 161 , 282. Plioladom\'a marjdandica, 62, 69, 78, 79, 185 , 295. Pholadomyidae, 184. Pholas petrosa, 161. Pholadidae, 161. Phyllodus, 112 . Phyllodus hipparionj'x, 113 . Ph\dlodus sp. aff. toliapicus, 113 . Phyllodus toliapicus, 112. Ph\"matocor 3 "on mackajd, 259. Pisces, 74, 75, 93, 98. Placosmilia (Trochosmilia) connivens, 229, 230. Plantae, 80, 81, 93, 258, 316. Platidia marjdaudica, 63, 72, 78, 79, 203 , 310. Pleurophoridae, 183. Pleurotoma childreni, 63, 74, 75, 85, 86, 121 , 272. Pleurotoma ducateli, 63, 74, 75, 126 , 272. Pleurotoma denticula, 127. Pleurotoma denticula var., 127. Pleurotoma harrisi, 63, 74, 75, 125 , 126, 272. Pleurotoma (Hemipleurotoma) chil- dreni, 127. PALEONTOLOGICAL INDEX 329 Pleurotoma nasuta, 126. Pleurotoma piscatavensis, 63, 74, 75, 121, 272. Pleurotoma potomacensis, 63, 74, 75, 126, 272. Pleurotoma tysoni, 63, 74, 75, 126, 272. Pleurotomella bellistriata, 128. Pleurotomiclae, 125. Polymorpliina anceps, 247. Polymorphina austriaca, 66, 80, 81, 2U, 315. Polymorpliina communis, 80, 81, 21flf, 248, 315. Polymorphina complanata, 246. Polymorphina compressa, 80, 81, 2.'i6, 315. Polymorphina cylinclroides, 246. Polymorphina eleffantissima, 66, 80, 81, 247, 315. PolymoriDhina froncliformis, 246. Polymorphina g-ibba, 59, 80, 81, 21^8, 249, 315. Polymorphina lactea, 63, 80, 81, 2.’iS, 315. Polymorphina praelonga, 66, 80, 81, ^2If9, 315. Polymorphina problema, 244, 245, 249. Polymorphina problema var. deltoi- dea, 247. Prionodesmacea, 185. Protocardia lenis, 59, 67, 70, 71, 73, 78, 79, 112, 288. Protocardia virginiana, 172. Protosphj^raena, 111. Protozoa, 80, 81, 233. Pseudoliva sp., 63, 76, 77, UO, 264. Pseudoliva venusta, 140. Pteria limula, 72, 78, 79, 85, 87, 88, 89, lO.’f, 303. Pteriidae, 194. Ptenoglossa, 153. Pulvinulina exigua var. obtusa, 80, 81, 255, 316. Pulvinulina karsteni, 256. Pulvinulina schreibersii, 67, 80, 81, 256, 316. Pyramidellidae, 155. Pyrgiscus, 155. Pyropsis pyrula, 137, 138. Pyropsis (?) sp., 138. Pyrula cancellata, 141. Pyrula elegantissima, 141, 142. Pyrula juvenis, 143. Pyrula penita var., 66, 76, 77, 85, 88, 89, Ul, 276. Pyrula (?) sp., 66, 76, 77, lJi.2, 276. Pyrula tricarinata, 141. R. Eachiglossa, 130. Ileptescharipora, 218. Eeptilia, 74, 75, 95. Eeptocelleporaria aspera, 220. Eeptofiustrella heteropora, 80, 81, 213. 312. Eeticulipora dichotoma, 63, 78, 79, 201, 311. Ehipidoglossa, 157. Ehizopoda, 233. Eingicula dalli, 67, 70, 74, 12J^, 272. Eingiculidae, 124. Eobulina concinna, 241. Eobulina radiata, 243. Eosalina ammonoides, 254. Eosalina bertheloti, 251. Eotalia (Trochulina) turbo, 251. Eotalidae, 251. Eotalina schreibersii, 256. Eotalina ungeriana, 253. S. Saxicavidae, 162. Scala carinata, 63, 76, 77, 154, 280. Scala potomacensis, 63, 76, 77, 154, 280. Scala sessilis, 63, 76, 77, 154, 280. Scala virginiana, 60, 76, 77, 153, 280. Scalariidae, 153. Scapanorhynchus, 103. Scaphandridae, 124. Scaphopoda, 76, 77, 158. Selachian vertebrae, 110. SemiescharijDora, 218. Serpula lactea, 248. Simpulum showalteri, 141. Siphonodentaliidae, 159. Solariidae, 153. Solarium sp., 60, 76, 77, 153, 280. Solen lisbonensis (?), 65, 76, 77, 165, 285. Solen (Plectosolen) lisbonensis, 165. Solen (Plectosolen) lisbonensis var. abrnptus, 165. Solen sp., 165. Solenidae, 165. Solenoconchia, 158. Solemya petricoloides, 186. Spatangidae, 232. 330 PALEONTOLOGICAL INDEX Spatang-idea, 232. Sphyraena speciosa, 111. Sphyrna, 109. Spliyrna denticulata, 110. Sphyrna i^risca, 61, 74, 75, 110, 266. Spiroihecta americana, 235. Spiroplecta biformis, 236. Spirof)lecta clarki, 66, 80, 81, 235, 314. Sqnalus aiiricnlatus, 108. Strepsidura subscalarina, 59, 70, 74, 75, 136, 274. Strombidae, 145. Synechodns, 102. Synechodus clarkii, 61, 74, 75, 103, 266. Syrnola trapaqiiara, 156. T. Taenioglossa, 141. Tectibranchiata, 123. Tectospondyli, 98. Teleodesmacea, 160. Teleostomi, 110, 264. Teleotremata, 203. Tellina greg-gi, 166. Tellina siibtriangularis, 167. Tellina virginiana, 59, 76, 77, 166, 285. Tellina williamsi, 76, 77, 167, 285. Tellina (Angelus) virginiana, 166. Tellina (Peronidae) iDapyria (?), 76, 77, 167 Tellina (Peronidia ?) williamsi, 167. Tellinidae, 166. Terebratellidae, 203. Terebratula harlani, 61, 78, 79, 194, 20J^, 310. Terebratnlidae, 204. Teredinidae, 160. Teredo virginiana, 76, 77, 160, 282. Testndenata, 97. Tetrabranchiata, 122. Textularia abbreviata, 233. Textnlaria hauerii, 233. Textularia gramen, 63, 80, 81, 233, 314. Textularia sagittula, 63, 80, 81, 231f, 314. Textularia subangulata, 61, 80, 81, 231f, 314. Textularidae, 233. Thecaehampsa antiqua, 96. Thecaehampsa eontusor, 61, 74, 75, 96, 262. Thecaehampsa marylandica, 60, 74, 75, 96, 262. Thecaehampsa sericodon (?), 61, 74, 75, 95, 262. Thecaehampsa sp., 60, 74, 75, 95, 262. Tornatella bella, 123. Tornatellaea bella, 59, 66, 70, 74, 75, 85, 86, 88, 123, 272. Toxoglossa, 125. Trigonoarca decisa var., 78, 79, 85, 88, 195, 303. Trigonoarca pulchra, 195. Trigonoarca pulchra var., 195. Trionychia, 97. Trionychidae, 97. Trionyx virginiana, 61, 74, 75, 97, 263. Tritonidae, 141. Tritonium showalteri, 63, 76, 77, llfl, 276. Trochidae, 157. Trochocyathus clarkeanus, 60, 62, 80, 81, 225, 313. Trochosmilia connivens, 229. Trochus apertus, 152. Trophon sublevis, 63, 74, 75, 85, 86, 135, 274. Truncatulina boueana, 253. Truncatulina grosserugosa, 254. Truncatulina lobatula, 80, 81, 251, 252, 316. Truncatulina refulgens, 252. Truncatulina ungeriana, 59, 80, 81, 253, 316. Truncatulina variabilis, 253. Truncatulina wuellerstorfi, 253. Tuba marylandica, 76, 77, 155, 281. Tubuliporidae, 205. Tudicla marylandica, 63, 76, 77, 137, 275. Tudicla sp., 61, 62, 76, 77, 138, 275. Tudicla (?) sp., 76, 77, 138, 275, 276. Turbinella pyruloides, 131. Turbinolia acuticostata, 43, 62, 80, 81, 223, 313. Turbinolia elaborata, 229. Turbinolia pharetra, 224, 225. Turbinolia pileolus, 231. Turbinolia wautubbeensis, 224. Turbinolidae, 222, 223. Turbonilla potomacensis, 63, 76, 77, 155, 281. Turritella humerosa, 60, 61, 64, 69, 71, 72, 76, 77, 85, 86, UfS, 279. Turritella mortoni, 60, 61, 62, 64, 68, 69, 72, 73, 76, 77, 85, 86, U7, 148, 149, 278. TALEOXTOLOGICAL INDEX 331 Turritella mortoni var. postmortoni, 147. Turritella obruta, 149. Turritella potomacensis, 67, 70, 71, 76, 77, U9, 279. Turritella venusta, 149. Turritellidae, 147. V. Vaginulina leg'umen, 61, 80, 81, 210, 315. Venericardia, 177. Venericardia ascia, 177. Venericardia marjdandica, 67, 78, 79, m, 292. Venericardia pectuncularis, 179. Venericardia planicosta, 177, 178. Venericardia planicosta var. regia, 60, 72, 73, 78, 79, 85, 778, 290, 291, 292. Venericardia potapacoensis, 64, 65, 66, 69, 70, 71, 72, 78, 79, 119, 292. Venericardia regia, 178. Veneridae, 168. Vermetidae, 150. Vermetus sp., 60, 76, 77, 150, 279. Vertebrata, 95. Voluta petrosa, 130. Volutidae, 130. Volutilitlies (Athleta) tuomeyi, 130. Volutilithes petrosus, 59, 74, 75, 85, 86, 88, 130, 273. Volutilithes sp., 60, 74, 75, 131, 273. X. Xiphias, 111. Xiphias (?) radiata, 61, 74, 75, 112, 264. Y. Yoldia cultelliformis, 198. ERRATA. PAGE 61 line 10 for 63 “ 14 “ 63 “36 “ 63 “ 43 “ 80 “ 35 “ 81 “ 35 “ 82 “ 14 “ Plate XX “ Odotus ohliquus read Otodas ohliquus. Reticulipora dichomata read ReticuUpora dichotoma. 2Iarginula costata read Marginulina costata Fissuridea marylandica read Fissuridea marlhoroensis Marginula costata read Margin ulina costata therefore read their Cephalopoda read Gastropoda.