i PEPARTMENT OF THE INTERIOR. iz. II E r 0 11 T UNITED 8TATE8 GEOLOGICAL SURVEY THE TEBRITOPvIES UNITED STATES GE OL 0 G IST-IN-CH AEGE. VOLUME 11. WASHINGTON: G <) V K U N M E N T P R I N T I N O O !•' F 1 CI E , 1875. LETTER TO THE SECRETARY. Office of the United States Geological Survey of the Territories, Washington, D. C, October 5, 1875. Sir: The very vnliiablc niemuir, l)y Prol". K. D. Cope, on the " Verte- Iirala of the Cretaceous Formations of the West," is respectfully submitted for your approval and for publication. The great interest which has been excited among the peojjle, as well as among scientific men, l)y the discoveries of the remarkable extinct vertebrate remains, within a few years past, in the num- erous ancient lake-basins of the West, will render the publication very opportune at this time, and one of great value to the intelligent world. As a contribution of materials toward the solution of the numerous problems involved in the geological structure of our great West, as well as the unfold- ing of its ancient life, it must take the highest rank. In a certain sense. Paleontology, or the history of ancient organic remains, lies at the very foundation of geological science. It oftentimes stands as the arbiter on doubtful questions, and is a very important aid to the stratigrapher in unfolding the age of strata, and in fixing the great timc-bnnndaries o( groups, as well as divisions or sul»divisioiis. Xo geological survey can be considered complete without its cooperation. It has l)ecn with this idea that so much of the strength of the survey has been given to this department. So far as the opinions expres-sed by the author in regard to the age of the Lignitic group are concerned, he aloni' is responsible to the scientific world. In all the publications of the survey under my charge, prepared by collaborators of established reputation, I have thought it best to permit the broadest latitude in the expression of dpininns, w hetlier they liarnionize with my own conclusions or not. While Professor ( 'oiie reads, in the teachin"-s ot the extinct vertcbra'.e fauna of tlie Lignili>' irroiip, its Cretaceous age, Pro- IV fcssor Lesqucreux, with equal sincerity and force, decides, from tlic lessons of tlie fossil vegetation, that it belongs to the Tertiary epoch. The present volume will be followed in due time by two others by the same author, on the Vertebrata of the Tertiary Lake-Basins of the "West. I have the honor to be, your obedieut servant, F. V. HAYDEN, United States Geologist. Hon. 1>. R. CowEN, Acting Secretary oj the Interior. UNITED STATES GEOLOCICAL SURVEY OF THE TEIMIITORIES. THE VERTEBRATA CRETACEOUS FORMATIONS THE WEST By E. D. cope. WASHINGTON: GOVERNMENT PRINTING OFFICE. 18 75. CONTENTS. Letter to Professor Hayden lutroduction : on the significance of paleontological science PART I. On tbc classification and distribution of tlio Cretaceons deposits of the West. PART II. Descriptions of the Cretaceons Vertebrata of the West 1. Description of the localities and fauna 2. Literature of the Reptilia 3. Descriptions of the Reptilia 4. Li terature of the Fishes 5. Descriptions of the Fishes PART III. Synopsis of tlu- known Cretaceous Vertebrata of North America Page. 15 42 42 51 53 179 180 245 27889 LIST OF WOOD-CUTS Kic. 1. Diagram of teeth a{ Cionndon arctatun, page 59. 8. Sketch of bones of I'lolontena gigcs, taken at time of disrovery, i>.i. Femoral bones and ventral tin of a Poi-IIuiin, from above; a, from below; (/, from tlie side, page I'.l-J 10. Scapnla, ete., and base of ])eetoraI fin of I'llecoiilrnm diinii-tjKs, Cope, |iage 244 L!. Philadelphia, January 20, 1875. SiK : The accompanying pages embrace my final report on the vertebrate paleontology of the Cretaceous formations of the West. The greater number of species described has been derived from the beds of the Niobrara (No. 3) and Fort Union (No. 6) epochs. The material has been obtained from the explorations in Kansas by the writer in 1871 ; from similar explorations in Kansas by Prof. B. F. Mudge in the years 1870 and 1S72 ; from the explora- tions by the writer in Wyoming in connection with the United States Geolo- gical Survey in 1872; and from a similar expedition in Colorado in 1873. I wish to express here my indebtedness to various friends who have assisted me on these occasions ; especially to General John Pope, commanding the Department of the Smoky Hill, and Captains Butler and Lyman, and Dr. King, stationed at Fort Wallace at the time of my expedition in 1871 ; to Dr. John H. Janeway, United States Al-my, of Fort Hays, and Profs. B. F. Mudge and George Merrill, of Kansas, for invaluable specimens of the fossils of the Niobrara group ; and to Capt. E. 0. Clift, Dr. Joseph Corson, and Judge W. E. Carter, of Fort Bridger, Wyoming, for many kindnesses. I am also under obligations to George M. Dawson, geologist of the British North Amer- ican Boundary Commission, for the opportunity of examining fossils from the Fort Union lieds of British America ; and to the Smithsonian Institution for facilities in the use of specimens and books. AVhere it has been possible to throw light on questions of stratigraphy, this subject has also been touched upon. I am, with much esteem, E. D. COPE, Paleontologist. Dr. F. V. Hayden, Director of the U. S. Geological Survey of the Territories. ^CT' I ISr TR O D U C T I O N^ ON THE GENERAL SIGNIFICANCE OF THE SCIENCE OF PALEONTOLOGY. I. Paleontology is an exact science. It embraces generalizations or laws obtained by indnction, which may be dednctively applied to the unknown. Its first law is an illustration of the uniformity of nature's methods, namely, the law of the persistence of type. An organized structure once created, and existing under circumstances not hostile to its working, is adhered to with the greatest fidelity, and extended in time and space. This constant law is the key to this as to tlie other biological sciences, and occasionally surprises the student of evolutionistic proclivities. On this basis, the possibility of reconstruction of the extinct forms of the past will always rest ; and the cer- tainty of the law is unconsciously admitted by every paleontologist who determines, names, or classifies a fossil from anything less than a perfect specimen. It is assumed every day, and universally allowed, although occa- sionally even an expert is found who sometimes questions it, and still more frequently an inexpert who does not read nature aright. The application of tlie law is, however, various as the given terms, i. c, the remains preserved, ditfer in significance. Thus, to illustrate, certain parts are common to all stoves, and distinguish them from all other article?t of furni- ture; but certain other parts not only belong to a stove, but mark a given pattern of stove, since they belong only to it. A still more minute range of appearances is found only in one man's make of stoves, and others in tiiat of another man. Hence, a person acquainted with stoves, sewing-machines, &c., can readily determine the origin of a very small part by referring it to its projicr kind and make. The application of this law of persistence presupposes a knowledge of the pattern as essential to its deductive application. Hence, a difliculty at once suggests itself as arising when a portion of an aninial belonging to a new 8 pattern is discovered. That patterns quite distinct from those known to zool- ogists have existed in past ages has been well proven by paleontologists. How can the structures of a species of such a kind be inferred from a frag- ment ? Another law equally true with that of persistence has been developed from the facts, but it is much more difficult of application. This is the one already defined by the writer^ under the name of the law of " successional relation.'' It is absolutely certain that the types of nature, whether pri- mary or subordinate, form series of steps passing from one condition of rela- tions to another. The natural deduction is, that if a portion of an animal exhiljits a form intermediate between two known forms or types, the remainder of the animal's structure possesses the same kind of intermediacy. This law is tacitly admitted, and employed by paleontologists ; but there is a diffi- culty of application in consequence of the existence of other laws now to be considered. The first difficulty arises from our possible ignorance of one terminus of the series or hue in which our fossil represents a stage. This objection is more theoretical than real, because the living classes and orders are the struc- tural extremes of the lines of succession ; nevertheless, among divisions of lesser range, many have reached their culmination, and disappeared in times past. These points of culmination must be known in order to ascertain the direction of the succession. Every discovery, however, is not that of an advanced position on such lines ; intermediate positions being necessarily more numerous than termini. Hence, this difficulty is of only occasional recurrence. The preceding considerations all express different phases of the law of uniformity. I now refer to the law of variation, which is in apparent conflict with it. It is the law which expresses evolution as opposed to persistence of types. It especially limits the application of the last law, that of uniformity in succession ; i. c, that when one portion of structure occupies a position intermediate between two already known types, the remaining parts of the same animal or system of organs will occupy the same relation of structure to the corresponding parts of the known. This is not uniformly true. The law of variation intervenes, which states that it may occur that, while one part of an organization occupies a relation of intermediacy, the other parts do not exhiliit exactly the same relation. It is by the unequal mingling of structural points that new lines of succession are marked out. Thus it is ' Pcuii Monthly Magazine, 1872, p. 229. that the power of reconstruction from fragments is limited, but not sufficiently so as to justify the epithet " pretension," which has been applied to the claim made. Besides, two other laws remain, which are of great importance to the paleontologist. Illustrations of tlic preceding laws may first be given. If a fragment of an animal be found, which contains a certain type of teeth known as the true selenodont, it is certain, in accordance with the law of uniformity of type, that the first bone of the hind foot of that animal (the astragalus) possessed two pulley-grooved fiices, one above and one below, and not one only, as in most animals; also, that the lower pulley-face was succeeded by two sub- equal toes, and that the lateral toes were either reduced in form or wanting. There is no mechanical relation between the structures of the teeth and foot ; their accordance is simply a fact of type of a selenodont Artiodactyle.' Again, if I find a portion of a foot which presents a joint between the first and second rows of bones which ibnn the sole, I am absolutely certain that the animal had the two outer ear-bones external to the skull, forming a part of the lower jaw and the connecting-rod by which the latter is attached to the skull. This is a type-law of the bird and reptile. Again, if I find a part of a foot of the structure just named, where the first row of bones of the sole is united into one mass, and closely embraces the leg-bone without being continuously united, I know that I have an animal with teeth, with a very long hip-bone and a very long series of united vertebra? (or sacrum) resting upon it — in other words, a Dinosaurian. The law of uniformity in successional relation is well illustrated by the genus Loxolophodon. The first bone of the foot (astragalus) of this animal exhibits characters intermediate between that of the elephants {Prohoscidia) and odd-toed hoofed mammals (example, tapir) ; the remainder of the skeleton does the same ; the neck-vertebrse are similar to those of the former, while portions of the skull reseml)le corresponding ones of the latter. The toot of a dinosaur is intermediate between that of a reptile and that of a bird ; so are the sacrum and pelvis. The sternum of a frog of the family Discoglossidce is intermediate between those of ordinary frogs and salamanders ; so are the vertebrae and ribs. Examples of the limitation of the latter rule are still more numerous. They may "be produced from the three cases cited. Thus, in the dinosaur, it ' Represented by a Kuiiiiiiiiiil. 10 might once have been said that tlic jaws did not partake of the intermediacy, because they all present teeth, and are never smooth, like those of birds. Yet birds with teeth have recently been discovered, which deprives us of the use of this character as a definition. In the discoglossid frog, the cranium is not intermediate in structure between the frog and salamander, but is that of a trog. Ill tiie Loxolophodon, the toothless front of the upper jaw is not a general character of either of the orders between wliich it stands. These difficulties arise from the existence of the subordinate variations or subtypes of a general or major pattern, and, for their resolution, require only a new application of the first law of uniformity on the lower plane. If the subcharacters defining the subpattern be known, the existence of one presupi^oses that of the others. The structure of an artiodactyle astragalus will not enable me to infer the character of the incisor-teeth of the animal; for this I require some other more minutely-correlated portion. So I can infer the ribs and vertebrae from the sternum of the discoglossid frog, but n(jt the cranium ; for this I require some part correlated with discoglossid char- acters only, and not only significant of the relations to the orders of Batra- chians, as are the characters mentioned, although it happens, by the accident of discovery, that none but such frogs are known to possess them to-day. The two laws vyliich further aid the deductions of the paleontologist are those of mechanical relations and of embryonic parallelism. One structure requires another in order that an animal be viable. Thus, long legs in a grazer presuppose a long neck to enable it to reach the ground with its lips. Hooked claws presuppose carnassial teeth or a hooked beak. For a horizontal body to be properly poised on two legs instead of four, the weight of the viscera must be transferred backward, and the anterior regions of the body lightened. This we find to be the case with birds and Dinosauria. The lower bones of the pelvis, with the contained organs, ai-e thrown backward, while the fore- limbs are lightened and the head reduced in proportionate (not absolute) size. The parallelism of types with transient embryonic conditions of other types, aids the paleontologist essentially in the classification or proper location of a specimen. Its relation to known series must be first determined, as this obviously precedes in reconstruction all application of tlie law of uniformity. Such reference having been made, either to a new series or to a place in a known series, the considerations heretofore adduced come into view, but not sooner. Hence, the law of parallelism is as essential to the paleontologist, as it is all-pervading and all-expressive of nature itself. 11 XL Paleontology in its relation to geology is as yet partially empirical. Thus, while its indications are definite for one locality, they have not identical significance for all localities on the earth's surface. The lower we descend in the scale of being, the more uniform over great areas are its phenomena ; but, among higher animals, esjiecially vertebrates, the greater the geographical peculiarities as compared with the stratigraphical. Professor Agassiz once said that the e.xisting geographical fauusB are more distinct than the extinct faunae of two consecutive epochs of geologic time; a statement justified by many facts. Hence, it has been believed by some, that fossil vertebrates cannot furnish conclusive evidence of the age of the rock-strata in which they occur; for, say they, we have to-day existing on the Australian continent, animals that approach more nearly to those found fossil in the Jurassic forma- tions of Europe than to any now living on the latter continent ; so that, were Australia to be presently submerged and her strata and fossils again brought to light, the paleontologist would assert that the sun had not shone on that land since the days of the Jura. And so he would were he not at the same time a zoologist; just as the bare zoologist would err in the opposite direction of assuming the modern age of the European Jurassic beds, because they contain the living types of Australia. Thus, a foundation-fact of zoology properly applied is essential to the paleontologist, namely, that the earth now presents four or more distinct faunal areas, the more prominent among which are the Australian, the South American, and the temperate lands of the northern hemisphere. Each of these possesses many pecuHar forms of life not now found elsewhere. Has this distinction always prevailed? Paleon- tology answers decidedly in the affirmative, so far as extinct mammalia are concerned. There seems to be no doubt that the faunal distinctions have a very ancient origin, and are therefore to be first considered when estimating the age of strata from the contained mammalian remains. The explanation of this diversity is not yet attainable ; but an important advance has been made by the discovery of the great similarity between the extinct forms of the northern hemisphere and the living or more modern ones of the southern hemisphere faunae. The Jurassic character of much of the Australian fauna is known, while prevalent t3'pes of South America and Africa can be shown to have much relation to Eocene types of the north. In North America and Europe, tapirs, opossums, coatis, civets, kinkajous, lemurs, and allies of the 12 toxodonts belong to the Eocene ; now these animals characterize the southern continental life, or, as is the case with toxodonts, have but recently become extinct there, ^fhis mode of defining those faunae is not, however, exact, since many modern types have found their way into them, especially in the case of Africa. How, then, is life significant of chronological station in the earth's strata? Since very many forms of animals are so widely spread and at the same time so distinctly limited in range on the earth's surface to-day, the same order must have prevailed in past time, and have been of equal significance. That this law of uniformity has prevailed in the past as in the present is amply proven by the paleontology of a single zoological area taken by itself. The apparition of types over the northern land-area has been nearly universal. This fact has only been placed within our reach by modern investigations in North America; for, until the sister continent of Europe-Asia was explored, no one could be sure what degree of individual peculiarity her extinct life might present. Now it is certain that the succession of Tertiary beds was mutually similar, and that the contemporaneous deposits contained in a large degree similar life, and that intermediate stages of the one can be properly intercalated in the vacant interspaces of the other. The resemblances be- tween the Lower Eocenes of New Mexico and Wyoming and that of France are marked ; similarity between the Pliocenes of the respective continents is evident. Descending in the scale, the parallels between the North American and New Zealand Cretaceous are very apparent, and the faunae of the Caro- linian and Wiirtembergian Trias were the same. The interruptions in the record of life marked by the appearance of great land-areas near the close of the Carboniferous and Cretaceous periods are universally observed in the zoological areas of the northern hemisphere, or Arctogsea. The close of the Cretaceous everywhere saw the end of ammonites, rudistes, and sauroptery- gian and dinosaurian reptiles, in spite, in North America at least, of physical continuity of deposits. Was this succession of interruptions of life universal over the globe, and do these trenchant lines justify the old assumption of repeated destructions and rcTcreations of animal life'? The former question has already been answered in the negative by the explanation of the characters of the existing faunae of the southern hemisphere, where ancient types sfill remain in con- siderable numbers. Moreover, some of (he later periods of both N(uth 13 America and Europe are characterized l)y a large predominance of forms of the corresponding southern continent. It is, indeed, evident tiial inigrafioii from tiie one continent lo the otlier has taken place, and is amply sufficient to account for the abrupt changes in the life of each, without necessitating the intervention of creative acts. If glacial periods be dependent on cosmic movements, the increased obliquity of the earth's axis to the sun, at periods 25,000 years apart, due to the same causes as precession, would cause a coi-- responding alternation of cold periods in the opposite hemispheres. This is well known as a most potent cause of migration and extinction, and the known relations of the faunae would thus result from a greater or less alter- nate invasion of the one hemisphere by the life of the other. But within the great time-boundaries are distinct land-fonnjc whose striking distinction may not thus be accounted for. Tims, the Miocene and Loup Fork faunae of Western America are entirely distinct, but with corre- sponding members. The alternate presence and absence of water-areas adapted for the preservation of the remains of the animals will abundantly account for such minor interruptions. Such changing topogra})hy is well known as due to the slow vertical oscillations of the earth's crust. The original question, the exactitude of the chronological significance of structural types, has been momentarily held in abeyance. Is paleontology a science so far exact as to furnish a chronological scale of terrestrial strata? The admission that the known Tertiary faunae, for instance, are but fragments of a continuous succession, would appear to invalidate any such claim. It would indicate tliat tlie restriction of a given type to a given horizon is only a matter of discovery, and that another accident may at any time give it a new range. This objection has but little weight. Fragments though i:hcy be, nearly-related formations, as the Tertiaries, are obviously the visible portions of a serial succession of life. Like the bright lines in a spectrum, the order is not disturbed by the temporary obliteration of a part of the colors, but the visible portions indicate the relations of the component parts with ir.foUible certainty. The more universal the physical interruption, the more far-reach- ing tlie break in tlie succession of life in any one locality, the greater is the significance of remains of animals as indication of relation in time. Tin; change of faunae in Arctogaea at the close of the Cretaceous is a case in point. A dinosaur, sauropterygian, ammonite, or rudist are as definite indicators of 14 the life that precederl the change as a tapir or civet-like carnivore is of the age that foIlowesemys victus. Adocus lineolatus. Plastomenus punctulatus. * * * * Trionyx vagans. Ischyrosaurus antiquus. Plesiosaurus occiduus. Bottosa urus perrugosus. Polyonax mortuarius. Cionodon arctatus. Hadrosaurus 1 occidentalis. * * % * * * « « * Hadrosaurus occidentalis. ■ The identity and correspondence of the species in the two columns indi- cate that these remote localities contain the remains of the same fauna. Further, the presence of Dinosauria and Sauropterygia demonstrates its mesozoic character. A number of vertebrate remains was collected by George W. Dawson, ' Annual Report, 1870, p. 168. -Seo an interesting article by Prof. O. C. Marsh on tbe Geology of the Eastern Uintah Mountains in the American Journal of Science and Arts for March, 1871. -Aiiiiii:i1 Kcpoi-t (loldi-ado, ISIJiJ, p. ^d. *:^vv l;i;lli.-lin cfllif I'liiled .Slates (icologieal Survey, No. 1, 1^74, )>. Id. 27 of Montreal, geologist of the British American Boundary Commission, near the line of the northern boundary of the United States (latitude 49°),. within the drainage-area of the Milk River. The formations are regarded by him as belonging to the Lignite or Fort Union of Dr. Haydcn, and consist of green- ish and greenish-brown arenaceous clays of various degrees of hardness, fre- quently including small gravel-stones, and sometimes forming a hard cement between them. The fossils were found near the base of the formation, and "not more than one or two hundred feet above yellow arenaceous beds, which I conceive represent Cretaceous No. 5, and which are rapidly followed in descending by well-marked No. 4 with characteristic fossils." (Extracted from letter of Mr. Dawson.) The species are the following : Clastes, sp.; Compsemys ogmius; C. ? victus; Plastomenus costatus;^ P.coakscem; Trionyx ?vagans; Trionyx Isp.; ? Hadro- saurus .^sp.; Cionodon stenopsis. The dinosaurian remains are quite abundant, and indicate several species, but are mostly so fragmentary as to be unfit for determination. The diagnos- tic genera of this list are Compsemys, Plasto?nenus, and Cionodon; the species referred to Hadrosaurus being represented by caudal vertebrae only. The first-named genus is characteristic of the Fort Union epoch only ; the frag- ment referred to C. victus, the only species of the list previously known, is too small for final specific reference. The Plastomenus coalescens is represented by a moi-e perfect specimen than any other species referred to this genus from the Fort Union beds, but is not sufficiently complete to render the reference to this Eocene genus final. It is, in any case, not a member of any other known genus. One species of Trionyx is represented by a hyosternal bone, and is not definable ; while the fragment referred to T. vagans, thouglt closely resembling that species, is not large enough for final determination. The Cionodon, thougli based on incomplete remains, is quite sufficient for paleon- tological purposes. In conclusion, it may be stated that there are present two genera in this collection which are diagnostic of tiie Fort Union epoch, but no species cer- tainly so, though two species are probably identical with species of that epoch ; also, that the presence o^ Dinosaur ia refers the fauna to the Mesozoic series; and that there is no .satisfactory evidence of the co-existence of these reptiles ' Two R])pcitsaro |iriivisiiiii;i11y rpfiTrod to tlic Tertiary giiiiis I'liiilomniitu, Init :iri^ (oo frii^iiiriitary for liiial ili'd'iiiiiiiatiuii. 28 with Tertiary forms ; that the species referred to Flastomenus constitute an indication of affinity with corresponding Eocene forms. The presence of gar- fishes of the genus Clasles in this formation is as yet peculiar to this and tlie • Juditii l\iver locahties. As these gars have not heretofore been found in Nortli America below the Eocene, they constitute the first case of apparent commingling of Tertiary and Cretaceous animal life yet clearly determined. Yet the evidence is far from being as weighty in indication of Tertiary rela- tions as is the presence of the saurians in question as evidence of Mcsozoic character; for the gars, though now living, are an ancient typCj their allies having swarmed in the Jurassic seas, and it is therefore altogether reason- able that they should be found in fresh-water deposits of Cretaceous and Tertiary age. The rarity of the former deposits accounts for the late date of their discovery there. The longest known of these transitional faunae was discovered l)y Dr. Haydcn near the mouth of Judith River, in Montana. As determined by Dr. Leidy, it embraces the following Vertebrata: Hadrosaurtis mirabtlis ; Palceos- cincus costahis; Tro'udon formosus ; Auhhjsodon liorrldus; Bottosaurus? hiimilis, Trionyx foveatas ; Clastes occidentaUs {Lepidotus, Leidy) ; Lejndotus haydenii. The first four species of this fist are Dinosauria, antl hence diagnostic of the Mesozoic age of the formation. The Clastes indicates relation to the MilK' River fauna. That the Judith River ibraiation is Cretaceous would appear to have been the suspicion of ]\Iessrs. Meek and Ilayden when they originally described the deposit and its invertebrate fossils. Leidy suspected that the species "indicate the existence of a formation like that of the Wealden in Europe."' Meek and Hayden" remark : "We are inclined to think with Professor Leidy that there may be, at tlie base o(" the Cretaceous system, a fresh-water formation lil^e the Wealden. Inasmuch, however, as there are some outliers of fresh-water Tertiary in these lowlands, we would suggest that it is barely possible these remains may belong to that epoch." From the standpoint of the writer, these beds would be at the top of the Cretaceous, and more or less related to the Fort Union epoch. ]\Ir. Meek expresses himself^ cautiously with refer- ence to the age of the Fort Union and Judith River formations, as follows: ' Proceedings of the Academy of Niitiiral Sciences. Philadelphia, 1856, p. 73. - /,. i:, wm. i>. 114. ■'II::y(l('ii'M Aiiiiiuil Report for 187'2, p. 4G0. 29 " The occurrence of [I'os.sils specified] at the Jiiditii River localities would certainly strongly favor the conclusion, not only that this Judith I'onnation, the age of which has so long been in doubt, is also Cretaceons, but liiat even the higher tVesii-water Lignite formation at Fort Clark and other Upper Mis- souri localities may also be Upper Cretaceous instead of Lower Tertiary. That the Judith River beds may be Cretaceous I am, in the light of all now known oi" this rosion of the continent, rather inclined to believe. But it would take very strong evidence to convince me that tiie higher Iresh-water Lignite series of the Upper Mis.souri is more ancient than the Lower Eocene. 'J'hat they are not is certainly strongly indicated not only by the modern afKnities of their molluscan remains, but also by the state of preservation of the latter." I presume it is now apimrent that the presence of the orders Sauropte- rygia and Dinosauria establishes, conclusively, the Mesozoic and Cretaceous character of this fauna. This reference was made by the writer in 1869, and was, at that time, opposed to the views extant, both geological and pale- ontological. The following list exhibits the state of opinion on tliis point at that time and subsequently. 1856. Meek and Hayden, Proceedings of the Academy, Philadelphia, p. 63 ; referred them to the Tertiary. Meek and Hayden, /. c, p. 265 ; Lignite, referred to the Miocene. Meek and Hayden, /. c, 113 ; referred to Lower Tertiary. Leidy, I. c, p. 312 ; Thcspesius oocidentaUs {Hadrosaurus) ; referred to the 3{am?nrJia, and regarded as dinosaurian. Leidy, I. c, p. 89 ; Ischyrosaurus referred to the Mammcdia as a sirenian. 1860. Hayden, Transactions of the American Philosophical Society, p. 123; repeats former conclusions; Leidy refers llienpesius more decidedly to the Sauria, and questions relations of Ischyi'osaurus. 1868. Hayden, American Journal of Science and Arts, p. 204; Lignites regartled as Tertiary, from both vegetable and animal remains, from the Missouri and the Laramie Plains. Leconte, Exploration of the Smoky Hill Railroad Route, |). Go ; the Middle Colorado beds are "older tiian those of the Mis.souri or Great Lignite bed of llaydcn, which are prul)ai)ly Miocene," ttc. 30 1869. Cope, Transactions of the American Philosophical Society, pp. 40, 9S, 243 ; supposed mammalian i-emains proven to be reptilian, and the formation referred to the Cretaceous. 1871. Newberry, in Hayden's Annual Report, pp. 95-96 ; Lignite flora regarded as Miocene. 1874. Dawson, Report of Progress of the British North American Boundary Commission : on tlie Tertiary Lignite Formation, p. 20 ; Milk River beds regarded as lowest American Tertiary. Cope, Bulletin of the United States Geological Survey of the Territo- ries, No. 2 (April) : Fort Union beds of Colorado referred to the Cretaceous. 1875. Cope, Proceedings of the Academy of Natural Sciences, Philadelphia (January) ; Milk River beds regarded as Cretaceous. From the above, it appears that both paleontologists and stratigraphers, excepting the writer, have maintained the Tertiary age of the beds of the Fort Union epoch. Whether the Bitter Creek and Bear River groups of Hayden present much ditlerence of horizon remains to be determined. For the present, they are retained as distinct. VII. — THE BITTEE CREEK SERIES, mentioned by the writer as a distinct group, in the Proceedings of the Amer- ican Philosophical Society, 1872 (pubUshed on August 12), is apparently regarded by Mr. Meek also as representing a distinct epoch.' He says, " The invertebrate fossils yet known from this formation are, in their specific rela- tions, with possibly two or three exceptions, new to science, and diflferent from those yet found either at Bear River, Coalville, or indeed elsewhere in any established horizon,' so that we can scarcely more than conjecture, from their specific affinities to known forms, as to the probable age of the rocks in which we find them." On this account, and because of the great stratigraph- ical diflferences exhibited by the Bear River and Evanston coal-strata, I have followed Hayden in regarding the Bear River group, on the west side of the Bridger basin, as representing a distinct series of rocks, with present knowl- edge. On this account I omit, as heretofore, allusion to determinations I Ilajdcn'M Animal Rciioi't for 1872, pp. 4S9-4G1 ; piiblihliod April, 1873. 31 of age of the latter ioniiation as irrelevaut. in discussing the age of the Bitter Creek epoch.' My own observations on tlic relations of these rocks, made during the summer of 1872, have been, in a measure, anticipated by the detailed reports of Messrs. Meek and Bannister," which, with the older observations of Dr. Hayden and Mr. Emmons (of King's survey), leave little to be added. How- ever, as none of these gentlemen paid especial attention to the vertebrate paleontology, the bearing of this department in relation to the stratigraphy remains to be explained. As Dr. Hayden remarks, the Union Pacific Railroad, at Black Butte station, passes through a inonoclinal valley ; the rocks on both sides having a gentle dip to the southeast. This dip continues to the ea'stward to near Creston, where the beds pass under the newer Tertiary strata. Following the railroad westward from Black Butte, the same dip continues to near Salt Wells, where we cross an anticlinal axis, the dip of the strata being gentle to the northwest. There are minor variations in the dij), but the general result is as stated. They disappear five miles east of Rock Spring station, beneatii the later beds of the Green River Tertiary, which, at this point, presents a line of strike extending northeast and southwest, across the railroad, in the form of a range of bluffs, of considerable elevation. They are composed of lighter-colored and softer material than the Bitter Creek strata. The latter consist of alternating beds of hard and soft sandstone, with argillaceous and carbonaceous strata. The upper part of the series contains eleven coal-strata. At Rock Spring, I was informed that the upper was ten feet in thickness, and the next, four feet. Returning eastward, the heavier-bedded sandstone is low in the series at Point of Rocks, in consequence of the southeast dip, and tiie upper beds are softer and abound in fossil shells. At Black Butte station, the heavy sandstone-bed disappears from view toward the east, and the eleven coal-strata appear above it. About twenty feet above the sandstone, between two of the thinner beds of coal, the bones of the Agathaumas sylvestris were found, iml)edded in leaves and sticks of dicotyledonous plants, cemented together by sand and clay. Where the heavy sandstone-bed disappears below the level of the track of the railroad, in the course of its eastern dip, a thin ' Tliis cmirsi! li;is liefii iiiisiiiulorstood by Mr. Meek and otlieis :us iiii|ilyiii^ a design to i<;iio.c tlioso (Ibtcruiiiiatioiis. Uolh Mr. liiiiiiions and Mr. Mi'iOi arc clear in tbi; i-xprrssioii of tlmir conilu.sioiis a.s to the ago of (ho ISoar River i'|iiii;!i. 'Si:;; ll:!\d.-:i'.i Ammti.iI Keport for l^li. pp. l.'iT, '. 32 bed of coal, just above it, soon follows; then a bed of shells containing oys- ters, more and less numerous at different points, may be traced lor some distance before it also disni^pears. Near the latter point, a bed of Melanians and other fresh-water shells is seen a few feet above them. A section, carried for eight miles south of Black Butte station, exhibits the relation of the Bitter Creek series to the superincumbent Tertiarics very instructively. The whole series rise slightly to the southward, and more dis- tinctly to the westward, so as to form an escarpment as the eastern border of an open valley, which extends south from the railroad, just west of the station. The heavy bed of sand-rock is here, as elsewhere, the landmark and strati- graphical base-line. Moving south from the railroad, we keep along the strike of the lower coal-beds. Just above the sand-rock, the softer stratum thickens, and six miles from the station is covered with the debris of immense numbers of Lcptesthes crassatelUformis. Passing over the edges of the strata, toward the southeast, I connted eight beds of coal, separated by various short inter- vals, the eighth being the heaviest, and five or six feet thick. Above this one, three thin beds of lignite were crossed in succession, each accompanied with an abundance of leaves of chiefly dicotyledonous plants. Then came the ninth bed of coal, and then, in order, three more beds of lignite, with abun- dant leaves. During this time the ascent became less steep, and a number of short, level tracts were passed before reaching the upper bed of lignite. Beyond this, I passed another short Hat, which was marked by a number of worn banks of the light-ash color that distinguishes the material of the bluffs of the Grreen River Tertiary which overlie the coal-series near liock Sjirings. I had not ridden a (juarter of a mile before reaching a low line, from which one of my men picked up a jaw of a small mammalian, allied to the Bridger Hyopsodus or to Hyracotlierium of the Eocene of France and Switzerland, and a number of PaludinaASkG shells. I had thus reached the summit of the Bitter Creek formation, wliich did not appear to be much more than 350 feet al>ove its base at the railroad. In full view, a mile or two to the south, rose the first of the benches which constitute the horizons of the Green River formation. Between this and the first mammal-producing bed, just descril)ed, rose three banks, one beyond the other, measuring, altogether, 120 ieet ; perhaps the lowest was 10 feet above the first bank, and this one not more elevated above the last lignite and leaf-bed. In all of these I found l)()nes of (ircen River Verhbrala exceedingly abundant, but all dislocated and scaltcn'd, ^o as 33 to be rarely in juxtaposition. These consisted of the following species : Fishes : Clastes 1 glaher ; Reptiles : Emys megaulax ; E. pachylomus ; E. eu- tlinetus; Trionyxscutumantiqunni ; Alligator heterodon; Mammals: Orohijypus vasacciensis ; and fragments too imperfect for determination. In the third bank, in immediate juxtaposition with the remains just enumerated, I found another thin bed of lignite, but this time without any visible leaves. In a fourth line of low blutis, a little beyond, I found that remarkable mammal, Meialophodon armatus, with its dentition nearly complete, in connection with fragments of other mammals and reptiles. Behind these rises the first line of white bluff's already described, which extend away to the east ; to the west, they soon terminate in a high escarp- ment in north and south line with that of the Bitter Creek beds, already men- tioned as bounding a north and south valley. This and the suj)erjacent strata which we pass over in going south appear to be conformable to those of the Bitter Creek series beneath them. I say ''appear," for slight differences of dip are not readily measured by the eye; yet I suspect that the conformability is very close, if not exact, and similar to that mentioned by Meek and Bannis- ter as exhibited by the beds of the Washakie group which lie upon the coal- series east of Creston. The white bluffs add perhaps one hundred feet to the elevation. On their summit is a thin bed of buflT clay and sand-rock sim- ilar to the upper strata of the Bitter Creek series, and containing numerous shells and some scattered teeth and scales of fishes. I called Mr. Meek's attention to the specimens of these shells, which I sent him, and his reply was that most were of identical species with those of the coal-series (Creta- ceous), and that they presented no general peculiarity. At a short distance to the southward, another line of white bluffs extends across the line of travel. This is not more elevated than the preceding one. I only found remains of tortoises on it. Several miles to the south we reach another bench, whose bluflfy face rises four or five hundred feet in buttress- like masses, interrupted at regular in*;ervals by narrow terraces. Tliis line is distinguished f'or its brilliantly-colored strata extending in horizontal bands along the escarpment. They are brilliant cherry-red, white, true purple witli a bloom shade, yellow, and pea-green, forming one of th(> most beautiful dis- plays I ever beheld. The lower portions-are bright-red, wiiicli color predom- inates toward the west, where the bluffs descend to a lower elevation. 1 fi)und on them remains of a turtle {Emys cvtlnHtus, Cojje) and some borings 34 of a ? worm in a hard layer. On top of these are clay and slate rocks of a muddy-yellow color, with their various ledges rising to perhaps two hundred feet. Continuing now to the southeastward, along the old stage-road, we cross South Bitter Creek at the old Laclede station. Some miles south and cast of this point, a band of buff sandstones form a bluff of fifty or more feet in elevation. Below it lie more white or ashen beds, which contain i-emains of mammals and turtles, rather decayed. A short distance beyond these, and forty miles from Black Butte station, we reach tiie base of the enormous pile of sediment which I have called the Mammoth Buttes. These form a horse- shoe-shaped mass, the concavity presenting south and eastwardly, the summit narrow, serrate, and most elevated to the east, and descending and widening toward the south. I estimated the height of the eastern end to be at least one thousand feet above the plain surrounding it. Numerous mammalian remains^ demonstrated that this mass is a part of the Bridger Eocene; although, as Mr. Emmons, of King's survey, informs me, no continuous connection with the principal area west of Green River can be traced. The total thickness of the Green River and Bridger formations on this section cannot be far from two thousand five hundred feet, at a very rough estimate. The point of transition from the Cretaceous to the Tertiary deposits, as indicated by the vertebrate remains, is then in the interval betvi'een the last plant-bed at the summit of the buff mud-rocks and the mammal-bone deposit in the lowest of the ash-gray beds. Below this line, the formation must be accounted as Cretaceous, on account of the presence of the dinosaurian Aga- thau?nas sylvestris, and those above it, as I have already pointed out, Eocene," on account of the types of Mammalia contained in them. The authorities on the Bitter Creek formation have presented views more or less at variance with those entertained by the writer, or of such a dubious character as to fall very far short of the requirements of evidence. Dr. Hayden has regarded them as Tertiary and as transitional from Creta- ceous to Tertiary. Mr. King, in his very fall article on the Greon River Basin, definitely refers the lower part of the series to the Cretaceous, in the follov/- ing language:^ "We have then here the uppermost members of the Cretaceous series laid down in the period of the oceanic sway, and quite freely charged 'See tlio Monster of MaiDuioth Buttes, Penn Monthly Magazine for .ingnst, 1873. ^Ou Bathmodon, an extinct genus of Ungulates, February 10, 1872, Hayduu's Annual Keport (1872), p. 431 ; Annual Eeport for 1872, p. 645. 3 Exploration of tlic Fortieth Parallel, p. 458. 35 willi the fossil relics of marine life; tlien an uninlernipted passage of con- formable beds tlirough the brackish period up, till the whole Green River / basin became a single sheet of fresh water.'' He regards the line of the Lu npper bed of oysters as the summit of the Cretaceous, and the superimposed beds as Tertiary, in the following language (page 453): "while the fresh- water species which are found in connection with the uppermost coal-beds seem to belong to the early Tertiary period." He thus places the line some distance within what I have regarded as the Cretaceous boundary. Mr. Lesquereux, as is known, regards these beds as Tertiary, not only on account of their vegetable fossils, but also on account of the stratigraphic relations of the formation. His conclusion to this effect is consistent throuirh- out, and is a fact of the highest importance in this connection. Mr. Meek has fully discussed the age of this series in his interesting article in Hayden's Annual Report for 1872, the general tenor of whicli is indicated by the passage I have quoted from the opening of his remarks, in the beginning of the present notice of the Bitter Creek beds. His opinions may be cited as follows: In the Annual Report for 1870, he determined the same beds visible at Hallville as Tertiary; in that of 1871, three species of oysters from other parts of the Bitter Creek beds are placed in the Cretaceous list, each one with question as to the identification of species, a point, in the case of oysters, of first importance in the determination of the age of the deposit. The remarks in this report, as well as those in Mr. King's report, refer either to the much lower Weber River coal or to the different area of the Bear Rivcr group, and are consequently noticed under that head. In a paper on the age of these beds, published August 12, 1872, the writer asserted the Cretaceous age of the series. On this, Dr. Bannister, tjic com- panion of Mr. Meek, writes^ "that Mr. Meek, and, I believe, Mr. Emmons also, had considered that these beds might be Cretaceous; but lliis was rather on account of the change in the fossil fauna from pur(;ly fresh-water, as in the characteristic Tertiary of this region, to brackish-water marine, and tiie spec- ific affinities of a few of the fossils to California Cretaceous species, than from any very positive evidence. As far a.3 I know, the only evidence of this kind is in the identification by Professor Cope of the saurian remains found by us at Black Butte." It only remains to observe that the strata and coal of the Bitter Creek ' AoQual Ueport for 1873, p. 534. 36 group of the Cretaceous are either wanting on the western and southern borders of the Green River basin, or are concealed by the superincumbent Tertiaries. Instead of these, a comparatively thin bed of apparently unfos- siliferous quartzite or sandstone lies at a high angle against the bases of the Uintah^ and Ham's Fork Mountains, respectively, on beds of Jurassic age, which are probably Cretaceous No. 1 (Dakota). Tlie beds observed by Pro- fessor Marsh, on the south side of the Uintah Mountains, on Brush Creek, belong neither to the Dakota nor Bitter Creek epochs, but perhaps to No. 3, if, as Professor Marsh asserts, the oyster found in a superjacent stratum is Ostrea congesta, Con. It is, in any case, of no later date than the Canyon City or Weber River coals. Hence, the assumption of some writers that this dis- covery determined the age of the Bitter Creek series to be Cretaceous is without foundation in fact. VIII. — THE BEAR KIVER GROUP, of Hayden, occupies, according to him, a distinct basin, to the west of an anticlinal axis, which separates it from that of Green River. It is buried under Tertiary beds, the age of which has been a question of interest, and will be hereafter considered. In order to determine the relations of the two basins, a section was carried across the rim of the eastern, starting from the Fontanelle Creek, eighty miles north of the Union Pacific Railroad, and con- tinuing toward the upper waters of Ham's Fork of Green River to the westward. My notes are as follows : The beds of the Green River epoch dip gently from the point where my last notes left them, near to Rock Spring station, toward the northwest, all the way to Green River. The upper strata become slaty in character, and descend to the water-level at the river, where they form a high bluff. In these slates occur the fish-beds discovered by Dr. Hayden, as well as the insect-beds noticed by Messrs. Denton and Richardson. They are worn into towers and other picturesque forms at Green River City (see Hayden's Annual Report for 1870). Passing north from the railroad, up the valley of Green River, the slates display a gentle dip to the north, and eighteen miles beyond have disappeared from view. On both sides of the river huge mesas of the Bridger formation come into view; those ou the east extending to the ' See Hayden's Annual Report for 1870 ; Marsli, American Journal of Science and Arts, March, 1871. 37 Big Sandy River, and those on the west to Ham's Fork. A.t Slate Creek, further to the north twenty miles, a yellowish-brown sandstone rises into view, and continues to increase in importance toward the north. At the mouth of Fontauelle Creek, it rises on the east side of the river to a heigh'; of perliaps 250 feet, but sinks toward the north and east, from near the mouth of La- barge Creek, fifteen miles up the river. North of Labarge, a similar bed of sandstone rises again, ajid is immediately overlaid by white shales, resembling those of the Green River epoch, which have here a great thickness. Oppo- site the mouth of the Labarge, their lower strata are bright-red ; but, on the west side of the river, the sandstone only is visible. All the beds rise to the north ; the red beds forming the summits of the cliffs in that direction. In passing up Fontanelle Creek to the westward, the heavy beds of buff sandstone gradually descend, and the white shales come into view. I exam- ined the former for lignite and coal, but found none. There are several thin beds of a tough, carbonaceous material in the white shales (which I take to be of the Green River epoch). In the lower strata in this locality, as well as on the east side of Green River above the mouth of Labarge Creek, are nu- merous remains of fishes similar to those of Green River City, with insects and their larvae, shells like P«^?a and Cyrena, and millions of Ct/prLs. The larvae are dipterous, some nearly an inch long, and others minute and in pro- digious numbers. With them are found stems of plants, but no leaves. These beds rise with a very gentle dip, and, twenty miles from the mouth of the creek, terminate against stecplj^-inclined strata of earlier age. At this point the lower beds exhibit the bright-red colors that are so often seen in the lower part of the formation at other points. The uplifted beds form a ridge of high hills, having a north by east and south by west trend, across which the Fontanelle cuts its way in a deep cafion. This range is monoclinal ; the strata dipping 45° east, and their outcrop on the summit and western face. The first bed which forms the surface of the incline is rather thin, and is composed of a reddish quartzite without fossils, no doubt of Cretaceous age. lielow it is a stratum of highly fossiliferous bluisli limestone of Jurassic age, coniaining Pentacrin us asteriscus, M. and H. ; Trigonia, &c. Below this, a reddish sandstone presented a similar thickness, which may represent the Trias, which rests on a bluish-shale formation. We have now reached the base of the western side of the hills ; from their summit, wc have had a Ijcau- tiful and inicres)inrs 7 c 50 The Cretaceous ocean of tlie West was no less remarkable tbr'its fishes tliau tor its reptiles. Sharks do not seem to have been so common as in the old Atlantic, but it swarmed with large predaceous forms related to the salmon and saury. VcrtebrjB and other fragments of these species project from the worn limestone in many places. I will call attention to perhaps the most formida- ble as well as the most abundant of these. It is the one whose bones most frequently crowned knobs of shale, which had been left standing amid sur- rounding destruction. The density and hardness of the bones shed the rain off on either side, so that the radiating gutters and ravines finally isolated the rock mass from that surrounding. The head was some inches longer tlian tliat of a fully-grown grizzly bear, and the jaws were deeper in proportion to their length. The muzzle was shorter and deeper than that of a bull-dog. The teeth were all sharp cylindric fangs, smooth and glistening, and of irreg- ular size. At certain points in each jaw they projected three inches above the gum, and were sunk one inch into deep pits, being thus as long as the fangs of a tiger, but more slender. Two pairs of such tangs crossed each other on each side of the end of the snout. This fish is known as Forthcus molossus, Cope. Besides the smaller fishes, the reptiles no doubt supplied the demands of its appetite. The ocean in which flourished this abundant and vigorous life was at last completely inclosed on the west by elevations of sea-bottom, so that it only communicated with the Atlantic and Pacific at the Gulf of Mexico and th(; Arctic Sea. The continued elevation of both eastern and western sliores contracted its area, and when ridges of the sea-bottom reached the surface, Ibrming long, low bars, parts of the water-area were inclosed, and connection with salt-water prevented. Thus were the living beings imprisoned and sul)- jected to many new risks to life. The stronger could more readily capture the weaker, while the fishes would gradually perish through the constant freshening of the water. Willi the death of any considerable class, the l)al- ance of food-supply woukl be lost, and many larger species would disappear from the scene. The most omnivorous and enduring would longest resist the approach of starvation, but would finally yield to inexorable fiite ; the last one- caught by the shifting bottom among shallow pools, from which his exhausted energies could not extricate him. REP'J'ILIA. LITERATURE OF THE SUBJECT. 1834. Harlan, in Transactions of the American Philosophical Society, v. IV, p. 405, pi. XX, figs. 3-8. Mosasaurus missuriensis. Snout de- scribed. 1845. Gohlfuss, ill Nova Acta Acad. K. L. C. Nat. Cur., XXI, p. 179, pis. vi, vii, viii, ix. Mosasaurus 7naximiliani described (with malar arch) (possibly remaining part of Harlan's specimen). 1856. Leidy, in Proceedings of the Academy of Natural Sciences, Philadel- phia, p. 8t^. Ischijrosaurus antiquus described. Leidy, /. sup. c, p. 73 ; six species of reptiles from the Fort Union beds of Judith River described. Leidy, I. sup. c, p. 311. Hadrosaurus occidentalis and two tortoises from the same beds described. 1-8G0. Leidy, Transactions of the American Philosophical Society, p. 145. All the species of the Fort Union epoch redescribed and figured. 1868. Cope, in Leconte's Notes on the Geology of the Extension of the Union Pacific Railroad, Eastern Division, on the Smoky Hill, p. Q)'6. Elasmosnurus platyurus described. 1869. Co|)e, in Proceedings of the Boston Society of Natural History, p. 250, January {separata). The ordcv Pi/tkononiorpha defined; the num- ber of cervical vertebrae, structure of the posterior regions of the cranium, of the lower jaw, scapular arch, and tore-limb first deter- mined ; genus Platecarpus defined. Cope, in Proceedings of the American Philosophical Society, June. Articulation of splenial bone in Pythonomorpha described ; genus Polycotylus described. (Jope, Transactions of the American Phihisophical Society. Part I of Synopsis of Extinct Batrachia, Reptilia, and Aves of North Amer- ica (to p. 104), issued in August. Elasmosaurus and Polycotylus described and Reptilia of Fort Union epoch determined. 1870. Cope, in Transactions of the American Philosophical Society, same work, part II (to p. 235), issued in April. Order Pythonomorpha further described, its genera further defined, and Liodon jrronger described. 52 Cope, Proceedings of the Aiiiericaii Philosophical Society, p. 574. Ij'io- don dyspelor, Platecarpus nmdgei, P. ictericus, and Clidastes chicrin- ruin described. 1871. Marsh, in American Journal of Science and Arts, p. 472 (separata Jnne). VoW\s 0^ Pythonomorpha first described, and the hind limbs for the first time stated to exist , and the species Clidastes dispar, tjc/ox, vymanii, and pumilus, and Ptei'odactylus owenii described. Cope, in letter to J. P. Le-sley, in Proceedings of the American Philo- sophical Society, p. 168 (separata October). Hind liml) of a Py- thonomorph first described, and Platecarpius latispmus and P. cras- sartus described. Cope, I. c, p. 172 (separata October). Protostega described, with hind limbs and pelvis of Liodon dyspelor. Testudlnata first recorded. Cope, /. c, p. 264, December. Catalogue o{ Pythonomorpha found in the Cretaceous strata of Kansas. Pterygoid bones first deter- mined, and hind limbs described ; genera determined, and six new species described. 1872. Cope, /. c, p. 308 (separata January). Cynocercus incisus and Hyposaurus vebbii described. Marsh, American Journal of Science and Arts {separata March 9). Pterodactylus ingcns and P. %-elox described. Name of P. owenii, changed to P. occidentalis. Scuta o^ Pytlwnomorpha described. Cope, Proceedings of the American Pliilosophical Society (separata March 11). Pterodactylus umbrosus and P. harpyia described. Cope, /. c, p. 403 (separata March). Protostega gigas fully described, and southern and eastern species named. Marsh, American Journal of Science and Arts (separata May). Deter- mination of position of phalanges of fore-limb, and of two addi- tional hones connected with the opistliotic in Pythonoiuorpha; cor- rection of position of the quadrate and confirmation of the previous locations of the malar arch and stapes ; description of six new spe- cies, and better definition of the genera Platecarpus and Liodon. Co|)c, in Proceedings of the Academy of Natural Sciences, Philadel- phia (separata June 6th). Descri[)tion of Plesiosaurus gulo. Coj)e, in /. sup. c. (separata June 8th). Review of Professor Marsh's paper of May, 1872; corrections of questions of nomenclature and disc(iv(M'v. 53 Cope, in Proceedings of the American Pliilosopliicnl Society (.sejfarafa August 12). Genus Agathnumas described. lS7;->. Cope, Proceedings of the Academy of Natural Sciences, Philadelphia, p. 10. Toxoclielys latiremis described. Leidy, Iveport of the United States Geological Survey of the Territo- ries, by F. V. Hayden. Clidastes affinis and Plesiosaurus occiduus described and other known species figured. 1874. Cope, in Hayden's liulletin of the United States Geological Survey of the Territories, No. 2 (issued April). Species of Cionodoii, Polyonax, Bottosaurus, Triony.i; PlastonieHuy, Adocus, C/idasfcs, and ,Liodon described; structure of Z?/'«os«wr/a of the Fort Union epoch eluci- dated. DINOSAUEIA. AGATHAUMAS, Cope. Proceedings of tbo American Pliilosopbical Society, 18T'J, p. 482. The characters of this genus are derived from the typical species A. syl- vcstrh, which is represented by dorsal and lumbar vertebrae and an entire sacrum, with tlie ilia, one nearly entire, ribs, and a number of other bones the character of which have not yet been positively ascertained. One of these resembles the proximal part of the pubis; others, portions of the sternum, &c. On eight (and, perhaps, nine) vertebra?, anterior to the sacrum, there is no indication of the capitular articular facet for the ril). This fticet is found, as in Crocodllia, at or near the base of the elongate diapophyses. The centra are slightly concave posteriorly, and still less so on the anterior face, with gently convex margins. The neural canal is very small, and the neural arch short, and quite distinct from the centrum, having scarcely any suture. The neural arch has a sul)cubical i'orm, partly truncated above by the anterior zygapophyses. In like manner, the base of the combined neural spine and dia- pophyses are truncated below by the square-cut posterior zygapophyses. The diapophyses are long, and directed upward ; they are triangular in section. There are eight (and, perhai)s, iiine) sacral vertebra?, which exhibit a con- siderable diminution in the diameters of the centra. The diapophyses and neural arches are shared by two centra, the anterior part of a centrum bear- ing the larger portion of both. The diapophyses are united distally in pairs; each pair inclosing a large foramen. 1'he anterior is the most massive 54 rest on Iheiliiiiu; the posterior pair llie most expanded; tlie superior mar- gins oi' its posterior edge form an open V, with the apex iorward on the neural arch of the fifth vertebra. On the last sacrals, the diapophyses rise to the neural arch again. The exits of the sacral spinal nerves are behind the middles of the centra, and continue into grooves of the sides in all but the last vertebrjE. The reduced and rather elongate form of the last sacral verte- l)ra induces me to believe that this animal did not possess such large and short caudal vcrtebrte as are found in the genus Hadrosaurus, and that the tail was a less massive organ. The iUinii is much more elongate than the corresponding element in Hadrosaurus, Cetiosaurus, or Megalosaurus. Its ujiper edge is turned and thickened inward above the anterior margin of the acetabulum, and here the middle of the conjoined diapophyses of the second and third sacral vertebra; was applied when in place. In front of this point, the ilium is produced in a straight line and a stout flattened form with obtuse end. Posterior to it, its inner face is concave to receive the second transverse rest of the sacrum, and the superior mai-gin is produced horizontally toward the median line like the corresponding bone in u bird. The posterior j)ait of the bone is the widest; for it is expanded into a thin plate and produced to a considerable length. From one of the margins (my sketch, made on the ground, represents it as the upper), a cylindric rod is pi'oduced still farther backward. This it is believed is only the shaft of a displaced rib. The base of the ischium is co- ossified with the ilium, and is separated behind its base from the iliac portion of the acetabulum. There is no facet nor suture for the pubis at the front of the acetabulum. The ribs are compressed. There are no bones certainly referable to the limbs. The form of the ilia distinguishes this genus from those known hereto- fore. Agathaumas sylvestrls, Cope. Proceedings of the American Pliilosopbical Society, 1872, p. 4"i'J. The last nine dorsal vertebras have rather short centra ; the most poste- rior the shortest. They are higher than wide; the sides are concave, the in- ferior face somewhat flattened. The neural arch is keeled behind from the canal to between the posterior zygapophyses, and a similar keel extends from the base of the neural sjiinc to between the anterior zyga])oj)hyses. The 55 neural spine is elevated uud compressed; the diapophysis is convex above and concave along the two inferior faces, most so on tin' posterior. The articular face of the first sacral vertebra is wider llian deep. The eight sac- ral vertebrae are flattened below, in all except th(! first, by a plane which is separated from the sides by a longitutlinal angle. The neural sphies of the anterior five sacral vertebra; are mere tuberosities. A large sutural surface for attachment of a transverse process is seen on the posterior Ihird of the eighth sacral vertebra, which descends nearly as low as the plane of the in- ferior surface. On the 1 tenth sacral, there is no such process, but its neural arch and that nf" the '. nintli support transverse processes. I^hese are mon; likr those of the dorsals in having lliree stmng l)a.'s, and others. Cionodon differs in dentition from all Dinosauria where that part of the structure is known; but it remains to compare Polyonax \\\i\\ Tro'udon and Palceoscincus of Leidy, which are known from the teeth only, while no portions of dentition are preserved with the specimens at my disposal. Ckar. gen. — Established primarily on a portion of the right maxillary bone, with numerous teeth in place. The posterior portion exhibits a suture, |)robal)ly for union with the palatine bone, while the rest of the interior margin is free. It is removed some distance from the tooth-line in con.sequence of the horizontal expanse of the bone, while the outer face is vertical. The teeth are rod-like; the upper portion subcyliudric in section, with the inner tiice flattened from apex to base, whiic (he lowci' half is flattened by an abrupt excavation to the middle, for the accomnioilalinn of the crown of the successional tooth. The inner face of I lie tooth, from apex to base, is shielded liy n plate of enamel, which is somewhat elevated ;il the iiiiirgins, and 59 supports a keel in tlic middle, thus giving rise to two shallow loiigitudiual troiiijhis. Tlie reiiKiiiuler of the tooth is covered with a layer of some dense substance, possibly cenientuin. which overlaps the vanishing ninrgins of the enamel. The outer inferior excavation of the shaft presents a median longitud- inal groove to accommodate the keel of the closely-appressed crown of the successional loolli. The apex of the tooth being ob- tusely wedge-shaped, the func- tional tooth is pushed forward and transversely toward the inner side of the jaw. The tooth slides downward in a closely-fitting ver- ^'^o- l.-Diagr-im of the umsillary dentitiou of Cionodon arctatiig : o, griucliiig-fncK ; ft, superior or radical view of tical groove of the outer alveolar the maxillary boue. natural size. wall. The inner wall is oblirpie, its section forming with that . 2. ' ' Char, specif. — The enamel-plate of the tooth extends from apex to near the base of the shaft. Its margins are thickened and without serration, while the surface generally is nearly smooth. The dense layer over the remainder of the tooth is much roughened by a great number of shorl, serrate, and somewhat irregular longitudinal ridges. 31easurements. M. Width of the alveolar groove - 0. 0120 Length of a triad of teeth on the alveolus 0. 0140 Lengt h of an iiuworu tooth 0. 0^)50 Diameter of the surface of attrition of a tooth of the middle row : Longitudinal 0.0063 Transverse 0.0072 Width of the maxillary bone 0.0350 Depth of the maxillary hone at the inner margin 0.0140 61 What I suppose to bo ilio poslrrior end dl' I lie inaxilliiry hoiic nxliihits the grooves to near its apex as well as a consideral)lc surface of articulation for the malar. Two dorsal vertebreB are preserved, whose neural arches are coossified, with a trace ol" the suture remaining. Both articular faces exhibit a transverse fossa for ligamentous or bursary attachment. Round these, on the convex face, there are transverse rugosities, while oliliquc-ridgcd lines descend on each side from the floor of the neural canal. The centra are shorter than deep, and subquadrate in a horizontal section. The sides are concave ; the anterior one compressed with lenticular vertical section with the angle below. The more posterior is less compressed, and the surface is smooth ; in the an- terior, it is thrown into weak longitudinal ridges near the edges of the articular extremities. There are large nutritious foramina on the sides. The neura- pophyses are excavated vertically on their posterior edges. Neural canal on the anterior dorsal, a broad vertical oval. A caudal vertebra is rather elongate and depressed ; as it has no diapophysis, it is not from the anterior part of the series. There is no prominent lateral angle, but the two inferior angles con- necting the chevron -facets are well marked. Neurapophysis only measuring half the length of the centrum. The articular faces exhibit the same trans- verse tbssa as is seen in the dorsals. The anterior is plane, the posterior reniformly concave. Measnrements. Anterior ilorsal : M. Length of tbo centrum 0.074 Elevation of the articnlar face 0.0?:? Width of tbo articular face 0. OTII Vertical diameter of the neural canal 0. 027 Elevation of the anterior zygapophysea 0. l'i'2 Middle dorsal : Leugth of the centrum 0. 0G8 Elevation of the articular face - 0. 08.'> Width of the articular face 0.080 Middle cautlal : Length of the centrum 0. 0(')2 Elevation of the articular face (at canal) 0. 047 Width of the articular face 0. OCH Width between the inferior angles n. H-'l Width of the uenral canal 0. Ui:! The femur is only represented by the distal end, witii the condyles per- fectly preserved. Tiie latter form a single trochlear surface, whost; borders form arcs of circles. It is slightly hour-glass-shaped, chiefly by excavation of the posterior lace, which is, however, shallow, the deep fossa; seen in 62 Hadrosdurus and other genera l)eing absent. The area of the ailieiilnr car- tilage is clearly marked out, and the dense snrface ol' the shaft is marked with delicate striae, which terminate at the edge of the former. One side of the end of the bone is nearly plane, the other is longitiidinally excavated ; some shallow grooves furrow the angle with the trochlear face. The section of the shaft, three inches from the end, is a wide, transverse parallelogram. This bone looks no little like the distal end of a metapodial bone, but there are Yarious reasons why it is more probably femur or humerus. The presence ot the tibia, especially, determines it to be the former element. The head and distal end of the tibia, with six inches of the shaft, are pre- served. The former relates with the end of the femur, resembling it both in size, simplicity of contour, and details of surface. The form is crescentoid ; one horn being the cneinial crest, the other posterior, and replaced by a short truncation. The inner (convex) flrce is rendered angular by a median tuber- osity, and all round this margin shallow grooves cut the solid angle at irreg- ular distances. The articular face displays the smooth area, and the shaft the delicate strise seen in tlic femur. The distal end is nnsymmetrically lenticu- lar in section, one side being more convex ; the aiticular face; is rugose, show- ing a fixed ligamentous articulation with the astragalus. The convex iiice of the shnft is coarsely striate-grooved near the extremity ; on the other side, the intervening ridges are represented by exostoses or rugosities. The flatter side becomes the more convex on the lower ])art of the shnft. Miitr.uvcinnti:!. Ti-.iDsverso iliameter: il. Of the coudyles of the Hiiiiar - (I. OH-i Of tbo shaft of tho femur 0. Of.:! Diiimeter, fore and aft : or the iiiidclU) of the condyles 0. (J54 Of the side of the condyles U. 001) Of the shaft 0.0?8 Diameter of the head of the tibia: Greatest (1.102 Fore and aft 0. 091! Transverse 0. UOO Diameter of the shaft of tibia ((iroxinially) : Transverse 0. OoO Foreandaft 0.045 Diameter of the distal end of the tibia : Transversely 0. 1 15 FortJand afc 0. 0(iO Remarks. — If the bones above described as pertaining to the hind linil) are really such, they are smaller as compared with the dorsal vertebra* than in Hadro^diiyns fau/hri. \\\h\ iiidifiite an aniniid as lar Diameter of tbe be.ad 0. liS Diameter of tbe sbaft 0. 098 Diameter of the distal eud (transverse), restored in part 0. 18 Should the humerus have been related to the fore-limb, as in Flesio- saurus dilichodirus, Conyb., the latter would have had a length of 4 feet 3 inches ; as the proportions of the radius and phalanges are shorter, the limb was probably relatively shorter. If related to the total length, as in the same Plesio.saur the humerus would indicate a length of \lh feet. The cer- vical vertebrae become attenuated, as compared with the dorsals, to a greater degree in Polycotylux than in Flesiosaurus. ELASMOSAURUS, Cope. This genus has been more completely preserved to us than any oilier American representative of the order. In the interpretation, however, con- siderable care is necessary, as the form appears, at first sight, to reverse, to a remarkable degree, the usual proportions of known reptiles. The scapular arch, in the absence of the episternum, presents the same number of ele- ments as the pelvic, and is not without resemblance to the latter, as it exists in some species of the order. The fortunate preservation of the series of cervical vertebraj shows this to have been, in the typical species, three times the lenglii of the body; much exceeding in this disproportion that knowu to exist in other species of the order. The neural arches are everywhere continuous with the centra, witiiout sign of suture, and are externally plane. The nenial canal is exceedingly small for the size of tlic vertebra;, especially on the lumbar and caudal verte- br;e. 76 The dorsal vertebra arc remarkable from tlie fact that the diapophyscs disappear on the anterior part of the series, and gradually diminish in length from behind forward to the point of disappearance. On the median and posterior parts of the series, they are very elongate, and rise for a short dis- tance from the basis of the neural arch. Anteriorly, they descend and shorten, and finally remain only as the slightly-elevated borders of rib-pits. Through- out the whole of the anterior portion of the column to the cervicals, the neural spines are of great elevation, and of such antero-posterior extent as to be nearly continuous. The cervical vertebrm are not only more numerous, but become anteri- orly much smaller and more attenuated than in its allies of the same family. They are remarkably compressed, the centra much longer than deep, and deeper than wide, and with smooth concave sides. The ribs of the anterior cervico-dorsal region are inserted directly in the vertically-oval pits of the centrum. Immediately at the point where these cease, thin traverse processes appear to arise from the lower edges of the rib- pits. They form a continuous series with the ribs, and soon rise from the plane of the lower face of the centrum, and are directed obliquely downward. At the end of the cervical series, they are directed nearly vertically down- ward. The number of these vertebrae is very great; the anterior diminishing to a very small size ; the whole measuring a little more than half the total length. Most of the cervicals possess two venous foramina below, the dorsals two, and most of the caudals one. The resemblance of the caudals to the usual type of Plesiosaurus is seen in the fact that each bears near its posterior articular aspect, on the inferior face, a pair of articular surfaces for chevron-bones. Similar vertebrae had been described by Leidy as the caudals of a genus he called Discosaurus. The study of the present genus shows that they are really of the caudals of the allied genus Chnoliasaurus, the support caudals of the latter being the cervicals. The ribs are simple-headed ; the abdominal ribs seen in Plesiosaurus are possibly wanting, as none were found by the discoverer of the fossil, after a careful search. The end of the muzzle, with symphysis mandibuli, was preserved. This is flat, the symphysis co-osified and rather short, tlie premaxillary grooved at the intervals between the dental alveoli. The teeth are deeply implanteliquely flattened by the pressure ; the other cervicals have the bodies natu- rally flat, with the articular surfaces much less so than the median portion. Some of the caudals are obliquely distorted. • DescrijJtion. — Vertebrce. — The neck may be safely assumed as a point of departure, as it consists of above sixty mostly continuous vertebrae, which graduate to an atlas of very slender proportions. Most of them preserve more or less developed parapophyses. At the posterior extremity of this series sixteen are perfectly continuous, and in this portion a great gradation in form is apparent. The anterior are narrow, compressed, and similar to the more distal cervicals in the elevated position of the lateral angle; the anterior are subquadrate, thick, and with lower lateral rib, and stronger (f) pleurapophy- sis. In these respects, the latter resemble the dorsals which follow toward what I beHeve to be the tail. Four anterior dorsals are in one mass (figured in Plate 3) ; in this series, the lateral angle first approaching is finally lost in the margin of the rib-pit, the posterior thus resembling other dorsals. In a series of four anterior dorsals, which, like the preceding, are in their original continuous mass, those of one extremity have centra rounded in section, with inferior rib-pits ; those of the other have quadrate centra and elevated diapophyses; the former have the character of the first dorsals, the latter of the median dorsals. The posterior dorsals and anterior caudals form, in like manner, a continuous series of eleven vertebrae, fractured in four places. In them, the diapophyses steadily descend, reaching the inferior plane in the last; thus, with the reduction of the venous foramina to one at the seventh, indicating the point of transition from dorsal to caudal series. The zygapo- physes preserve the usual arrangement, but are much compressed, so that the 81 posterior or dowii-looking arc conHneul, and scarcfly sciuuatcd In an cmar- gi nation. The neural spines, at their bases, have a slight posterior ol)liquity ; and tlie superior portions lean strongly in the anterior direction. The inferior liml)s of the cervical pleurapophyscs appear to be entirely wanting. TIk; articular faces for the chevron-bones are seen at the extremity of the interior rib of the caudal. Of the cervicals, there are both axis and atlas. Of the caudal series, probably the distal half, at least, is lost. A single vertebra near the middle does not relate to either of those anterior or posterior to it. There ai'c, therc- ibre, at least four lost from that region also. There is a considerable interruption immediately anterior to the last dorsal vertebra. Three large vertebrae, with long diapophyses belonging here, were embedded in the hard matrix which protected the pelvic arch. These are far from relating immediately to the vertebrae preserved before and behind them. I estimate the number missing as follows: Seven of the four- teen dorsals preserved have more or less elongate diapophyses. In Flexio- auri, vertebrae of this character are much more numerous; in P. homalospon- dijlus, Owen gives seventeen. If we add ten to the series in the present species, it will give the abdominal space between the adjacent margins of the oo. pubis and coracoidea an extent equal to the length of the pelvic arch. This is rehitively shorter than in the Plesiosauri. Dr. Turner found that a space of " three or tour" feet intervened between the two portions of the skeleton, which was otherwise continuous. I think ten an average number to represent safely the missing dorsals. From the cervical proximal regions, probably three vertebrae are missing from two interruptions. The remainder of the cervical series exiiibits three interruptions. Most of the proximals have been broken medially, leaving the articulations solid, an advantage in determining their continuity. Three vertebra' and one-half are thus found missing in this region. The whole number of vertebrae preserved and Inst, with the relative lengths of each, may be stated as follows : 11 c 82 I'li-sciit. Lost . Total No. Lenglli. No. Length. l<,-ngtb.s. CraDium . .. TtichiK. Inches. 24. 22.3 37.0 CO. Inches. 24. Ccrvicals . . -. .. (W-1 M 21 257..'-) 5r>. 10 00.4 3i 10 30 27U.t^ Dorso-lumbars '.12. 10 120. 4 Total lo:u 43i ;->!(;. 30 This gives the totnl length to the animal of 43 feet 2 inches, wiiich, in- creased by the amount taken up by intervertebral cartilages, will give roundly about forty-five feet. Of this, twenty-two must be reckoned to the neck. . The cervical iicrtehrce are assumed to commence where the rib-pits cease anil the continuous lateral processes commence. This point is ascertained with difficulty on the specimen. It is, however, perhaps the same point where tile hmgitudinal lateral ridge leaves the upper margin of the rib-pit; and it was to the series of vertebrae which pass this point that the scapular bones, the clavicle, and the coracoid were found attached. On the anterior dorsals, the inferior margin of the rib-pit is most prominent, and is finally produced into the flat, thin process which is directed obliquely downward on the cervi- cals. Both these and the posterior ribs are crushed on the centra, and project obliquely below them ; their mode of attachment is thus rendered rather ob- scure. A similar structure exists in the posterior cervicals of Cimoliasaurus, while, on the anterior dorsals, short, tiiick diapophyses support the ribs, The proximal cervicals are remarkable for their compressed and elongate form. They are, for a considerable distance, longer than any dorsals. The lateral longitudinal ridge rises successively nearer to the neural arch and disappears. The articular .surfaces are vertically oval, flattened above and below. The inferior faces are slightly grooved in line with the venous foramina. These vertebrae diminish in length, and, in front of the posterior third of the series, materially in depth. They diminish to terminal ones of very small size. In most, the decurved (?)parapophyses are broken near the base; but the l)asal pnition of various lengths generally adheres. The}' are as wide as a rib and scarcely half as thick. They have much greater antero-posterior extent on tlie terminal than the proximal cervical centra, having a base five-sixths the length of the latter. The zygapophyses have relatively a larger size on these 83 than iiii\ (jIIk r \( r1il)i;i'. In siicli. Ilic (•ciilniiii is Ics-; ctJiiipressed I lnuiali wifli concave sides, and witli a section rallirr ([luidratc. Tli(! coi-vicid vcit('l)rii', IVoiii Ilic sixty-sixtli to flic Inirty-niiitli, arc all longer than the dorsals : thcv eoninicnce I'onr inches in Icnsith, increase 1o five, and diminish (o tonr auain. ^f^■allnrcmentll. Iix-lirs. l.illf. I.iiigtli i>tsixt.v-lliii.I i-iivical 4 !».■-' De]>lli oftlie articiiliir (ace of tbo ciMitniin :> (•. Wiiltli of tilt! articular face of the (U'lilniin •! 1". - Total elevation of the uinth cervical - '.'. Anterior posterior diameter of tbe third cervical '■i -• Transverse diameter of the tbiril cervical 2 11. Length of the head of rili 1 !'• ' Width of the head of rib 1 X Widthof the shaft of rib 1 It'.-'' Many of the r/hs jireserved have been pressed upon the vertebra- and crushed. The first dorsal is that vertel)ra which first presents a distinct articula- tion for a rib. The diapophyses are never much elevated above the cen- trum, and are longest on the thirteeiitii (inserting seven supposed to be lost). Their form is stout and much depressed, and distally expanded. They dimin- ish gradually, and, on the third, are represented by a longitudinal angulation; the superior angle is first distinct on the first, and bounds the articular sur- tiice last on the third. They give the transver.se section of" the posterior eer- vicals a pentagonal form; that of the anterior dorsals is nearly circular. The latter are strongly constricted medially, and the articular faces are slightly concave. The external surfiice near the included angle is coansely ridged, in conformity with coarse cellular texture of the spongy bone. The venous foramina gradually become more widely separated, approaching each other again on the posterior cervicals. On the dorsals, they occupy the bottom of a more or less pronounced concavity. These concavities, on the posterior dor- sals, are bounded externally by a strong obtuse longitudinal angulation, giving a fpiadrate outline to the section of the centrum in this part of the series. The posterior cervicals are not readily distinguished from the anterior doisals. In the latter, the ril)s appear to be present, of reduced length, judg- ing from the smaller size of the remaining licads. The artieidar pits continue to descend till their lower marginal ridge is.*he inferior lateral angle of tiie vertebra. On such vcrlebrar^, the inferior surface is flat. 84 Measurements. ]u 3. Vertical posterior diameter of the articular face :i 10. Trausvcrse posterior diameter of the neural canal 10.2 Transverse posterior diameter of the articular face of the third dorsal 5 2.5 E leva, ion of the centrum, arch and spine of the second dorsal 1 19. Elevation of the upper edge of the zygapophysis of the second dorsal (i Length of the zygapophysis at the upper edge of the second dorsal 1 10.2 Length of the centrum of the last cervical 4 Width of the centrum of the articular face of the cervical 5 3. Elevation of the neural arch and spine of the cervical 7 9. Antcro-posterior width of the neural spine of the cervical at the zygapophysis 3 7. The caudal vertebrce have slightly concave articular surfaces, which are not bounded by groove or ridge. The neural arches have flat sides; and there is no longitudinal ridge above the diapophyses. The neural spines are ele- vated; the margins of those of the adjacent vertebrae close together. The diapophysis is very short aud wide, terminating in a large oval concavity for the pleurapophyses. Each limb of the chevron-bone is attached to an articu- lar surface on the lower posterior face of the vertebra at the extremity of a strong inferior ridge. These inferior ridges are rather close together, and distinguish the vertebra3 from those of Cimoliasaurus magnus, where they are wanting. They are absent on the anterior seven of the caudal series. The diapophysis is nearer the anterior than the posterior face of the vertebra. The venous foramen is single and median on all but the last six caudals. Me(xs^lrements. Inches. Lines. Antero-posterior diameter of the fourth caudal 2 4. Transverse posterior diameter of the fourth caudal 3 10.5 Total elevation of the fourth caudal 8 Vertical diameter of the centrum of the fourth caudal 3 1.5 Antcro-posterior diameter of the diapophysial iiit 1 9.2 Length of the ninth caudal 1 ".5 Transverse diameter of the articular face 1 •'■ Vertical diameter of the articular face 1 2. 7 Heads of fourteen ribs tire preserved, and a great number of shafts. The heads are simple, with cloiigate-oval articular face. They are oblique in the narrow direction, and fretpiently in their length also; the margins are somewhat everted. The extremities of the diapophyses of the larger dorsal v(>rtol)ia? are tntnsverse, some flattened, the others more oval; the more ante- 85 rior are siibtriangular; aud the rib-pits on the first dorsals an; siibround or vertically oval. Thus, the heads ol" the ril)s also vary. The shafts arc all flat, probably partly from pressure. They are frequently curve <) Greatest autero-posterior length of the precoracoid cavity 7 :i Transverse extent of the elaviculi t>7 Transverse extent of the coracoidia K; From the acetahulum to the foramen 7 0 The form of the posterior margin of the coracoidca is unknown, and tlicy are much broken on the inner margin. The greater part of the pelvic arch appears to be preserved. From the ol)liqiiity of the median suture, and from the ibrm ol' the pubes, as they arc preserved on a large nodule of indurated clay, it is evident that they have formed a boat-shaped supi)ort to the abdominal viscera, with an obtuse keel on the median line below. McnsuremcnU. Inches. LllH-H. Greatest aDtero-posterior leugth of the pubis and ischium 25 Greatest antcro- posterior leugth of the pubis 13 (', Antero-posterior median length to the notch of the ischia 7 Leugth of the coracoids behind the notch 4 f, (ireatcst wiillh nf the pubPR v;7 (i Greatest wiillh of lhi> ischi.i 21 8(^ 1 The anterior and lateral portions ot the piibes are very thin, as are also the median posterior portions of the ischiadic plates. The pubic bones are thickest on tiie posterior margin ; they present a downward-projecting median convexity near the anterior end. Depth of" the articular face, 2 inches 8 lines. » The superior surface of this arch was brought to light by the exertions of my friends B. Waterhouse Hawkins and William M. Gabb, who removed a large mass of matrix, which fortunately protected and accompanied it. This presents a transverse tliickening extending across it, and continuous with the posterior margin of tlie clavicles. A median longitudinal thickening extends from this to the anterior emarginatiwi, embracing in its angle with the trans- verse a shalbw concavity. The posterior projection, which is continuous with the median part of the ischia, is strongly detlexed behind the transverse rib, and is continuous with the basinlike concavity formed l)v the united pubes. The glenoid surface of the pubes is a sigmoid, while that of the ischia is regularly convex. The articulation of the ilium nas been exclusively with the former. Of the pleura])ophysial portion of the two arches nothing appears to be preserved except two lateral symmetrical long bones. One was found em- bedded in the mass carrying the pelvic arch, and they articulate well with the pnbes ; but the articular extremity is too short to articulate with ischia at the same time. Though they resemble the inferior view of the ])rocoracoids, they represent the ilia oi' Plexioaaurus. The head is subdiscoid, rather Hat, slightly j)rojecting eccentrically with a ligamentous pit. The articular surlacc is very oblique to the axis of the shaft, and is separated from the surtiice by a marked angle all round. Nothing like a trochanteric ridge is appai-ent in this bone. Measurements. iDcbes. Lines. Length iu tbo middle of the curve 9 9 Diameter jit the head 3 :S Diameter, distally, on the; curve (i Dianictor, distally, straight 4 The shaft is flattened cylindric : much flattened nearest the proximal extremity. The latter is very oblique to the shaft, and slightly convex neai- the proximal margin. The end of the muzzle preserved includes also the symphysis and parts of the rami of the mandible. '^I'lic ])!nts have been crushed together, ami \\\v. ST ends of" the teeth l)rokeii oil'. The alveoli ot the Iwo jaws iiifliiic ;i1 a iiai row angle to each other; hence the teeth, which iiltciiiatc, cross each other near the middles of the crowns. The purls preserved appear lo l)eloiiir 1o the premaxillary bone, though no suture can be found, and the bony walls are so thin as to render their ol)literation a probability. There is a keeled ridge along the middle line above, which is not continued to-fhe margin of the l)one. The form of the muzzle is narrow; tlie sides subparallel near the tip. which is elongate rounded. The mandil)ular synipiiysis, iiowever, is not very elon- gate, as the rami are given otf at three inches from the tip. The latter ap- |)ear to iiav(; l)een quite slender from tln^ various small sections or pieces sent with the nuizzle The premaxillary border of 4 inches 7 lines exhibits eight teeth, or their alveoli, of which tlie median two are close together, and not sep- arated by any mandibulars. The sections of the teeth are round or oval, and their sizes are irregular, jirobably on account of dilfering age and degrtu; ol protrusion. The diameters at alveolar margin vary from 6 lines to 3. Their form is slender conic, or, with the root, slender fusiform, and the pulp-cavity is small and median, sometimes cylindric, and sometimes narrowed. The surface, from a short distance above the alveolar margin to the tip, is marked with acute, threadlike ridges, which are sometimes interrupted, and .sometimes furnished with short branchlets. They are more or less undulate, and do not unite, but simply cease as the tip of the tooth is approached. The latter is smooth without lateral cutting-edges. The width of the mandible at the commencement of the rami is 3 inches 0.05 line; of the muzzle of the seventh tooth, 3 inches 7.5 lines; at the third tooth, 2 inches 4.2 lines. General liemarks. — The tail is a powerful swinnning-organ, more or less compressed in life: hence the specific name, which means tlat-tailed. The dang(!r of injury to which such an excessively elongate neck has been exposed wouhl render the recovery of a perfect sj)ecimen like the present an unusual accident. The neural spines of the dorsal region are so elevated and (dosely jdaced as to allow of little or no vertical motion of the column down- ward ; while, those of the cervical and caudal region being narrower, the elevation ol tiie head is (pate possible, and an upward ilexure easy. The iiabits of this species, like that of its known allies, were rapacious, as evinced by the numenius caniiielike teeth, and the tish-remains taken from beneath its vertebra?. The general Ibrui of tliis reptile was that of a serpent, \sitli a rejalivi-ly ■shorter, more rolmst, and nmre posteriorly-plnccil 88 body than is characteristic of true serpents, and with two pairs ot" hnibs, or paddles. It progressed by the strokes of its paddles, assisted by its jiowerlul and oarlike tail. The body was steadied by the elevated keel of the niediaa dorsal line, formed by the broad, high, neural spines. The siiakelike neck was raised high in the air, or depressed at the will of f lie animal, now arched swanlike, preparatory to a plunge after a fish, now stretched in repose on the water or deflexed in exploring the depths below. Comparisons. — In Cimoliasnurus magnus, the dorsals with elevated diapo- physes have considerably larger centra than those in which they are situated lower down. In E. platyurus, these vertebrae are oi" relatively equal length. The cervical pleurapophyses in C. magnus are anteriorly considerably stouter and less flattened. In comparing this species with the Cimoliasaurus grandu, Leidy, from Arkansas, we observe, first, the generic character of the strong inferior dia- pophyses in the latter. That species marks itself also as a pre-eminently short-necked form, as these anterior dorsals are even shorter than in C. ivag- 71US, being nearly twice as wide as long. The depth of the articular faces is also relatively greater than in the E. platyurus. Localities. — This species has been found in various parts of Kansas, lie- sides that from which the specimen above described was procured. Prof B. F. Mudge obtained vertebrae from a point thirty miles east of Fort Wallace, which probably belong to this animal. PLESIOSAURUS, Conybeare. Two American species have been provisionally referred to this genus : the P. lockwoodii, Cope, from No. 3 of New Jersey; and the P. gulo. Cope, from Kansas. This determination is only temporary, since the structure of the sternum, in which the type-characters of the sauropterygian families are to be observed, are unknown. The two species agree with Plesiosaurus, and difl!er from Elasinusaurus and Cimolianaurus in the non-coossification of the arches and centra of the vertebra?. Plesiosaurus gulo, Cope. The typical specimen consists of eleven cervical, thirteen dorsal, luid seven or eight other vertebrse, with portions of scapular and pelvic arch and ril)s. 80 The cervicals are longer than wide, and coiisiderahly compressed in form anteriorly, but depressed posteriorly. This is partly due to pressure, l)ut not wholly; and it is likely that the i)osterior centra are abont as transverse as in Cimoliamttrus magnus, Leidy ; while the anterior are relatively several times as long. In (he length, ihe latter resemble the English Plesiosauri, in which the centra arc also (•()nii)ressed. The compressed anterior centra exhibit a ridge on the side above the middle. A more massive ridge extends between the articular extremities at the lower part ol' the side, and presents a pit for the parapophysis. The pit for the neural spine is of nearly simihir size. Where the cervicals begin to be depressed, two foramina appear near together on the inferior face, and the articular extremities display an open obtuse emargination below. They are also eniarginate for the neural canal above, so as to have a form approaching a transverse figure 8. In the large; posterior cervicals, the sides are contracted both below and at the sides. In all the cervicals, the articular fiices are a little concave; in the larger, with some median convexities. In none of the dorsals preserved are the diapophyses seen to issue from the centra; hence the tbrmer are probably not posterior in position. The centra soon become smaller than those of the posterior cervicals, and are sul)round in section, with a well-marked emargination for the neural canal. The sides are gently concave, and are without angulation, but are marked near the articular extremity with short, sharp, and regular undivided ridges, eight in a half-inch. The articular faces are slightly concave and without ridges. There are the two inferior foramina, and one on the lower part of each side. The articular flice for the neural arch is an oval i)it extendinjr the lenirth of the centrum, and interrupted by some transverse ridges near the middle. The vertebrae diminish in size posteriorly. Two centra, probably .sacral, resemble the dorsals, but present an extensive vertical articular surface on each side. This facet has raised edges, and terminates al)ove in the longitudinal surface for the neural arch, having thus a T-shape ; it narrows beloAv to an obtuse point, and. \w doubt, support(!d a free diapopliysis. The fragments of tiie pelvic and scapular arches indicate that thov are capacious. The clavicle incloses a large t()ranuM), and is ihickened on the inner edge. The glenoid surface of the coracoid was wide and subrhombic. Some oF tiie other bones are cpiitc thin. The median suture of tiu; isciiiiini 12 c 90 is relatively aljuut as lung as in the P^nglisli Flesiosauri. and the adjacent part of the bone has a similar form. MeasuremenU. M. Lcii^lli of tljc iiiiturior ceivicul 0. 06'.i Depth 80 Thickness of the vertebral bone 0. 0070 TIjickness of the sternal bone 0. OOf^O From Lignite of Colorado, and mouth of Big Horn River, Montana. PLASTOMENUS, Cope. This genus has been discovered to embrace tortoises having characters of both Trwni/.r and Eniijs. The carapace is like that of the former, in the 03 iibsPiKc (if iirticiilated inaiginal bones, and the presence of a superticial cement layer, wliieli is sculptured in various patterns. 'I'lie plastron resembles that of some emydoid genera, but presents cej'tain fontanelles indicating an incomplete grade of ossification. The species known to possess the typical structure are Ibund in the Eocenes of Wyoming and New Me-xico; and those here referred to it are all IVoni IIk; Fori Union or Transition beds of the Cre- taceous. In none of them is the sternum so well-preserved as to exhibit the characters which should finally refer them to the genus Plastomenus. This i.s due to the fact that the\', as well as other vertebrate remains from this horizon, are always much broken or dislocated. Plastomenus coalesceks, Cope. This species is represented by large fragments of carapace and plastron (>r a single individual. These indicate a large animal of adult age. Tiie fragments are thick, and the sutures separating the component elements have disapjieared. Dermal sutnral grooves are also wanting. Tlie portions of the plastron preserved are emydoid in character, being most thickened in the lateral portions, especially in the inguinal region. The borders of the carapace are free and obtuse; at some points, somewhat thinned out. The ribs proper, in the portions preserved, terminate in a short, free extremity^ shorter than in nio.st species of Trionyx. There is no indication of the existence of marginal bones. The surfiice of plastron aixl carapace is covered with a dense layer, which is thrown into rather coarse, inosculating folds These lurni an open, reticulate pattern towards the middle portion of the cara])ace, and become obscure near the Ijorders They are well-marked on the plastron, and arc more or less longitudinal. The appearance is that of a Trionyx. The costal axis scarcely projects on the inner fiice of the carapace. Tiie anterior border of the carapace is a free, thickened margin, divided by a hor- izontal groove. The presence of nuchal l)one cannot be ascertained. Measurements. M. Tliickuess of the carapaco at tUu iiiidiUf of the leii^jtli of a costal boue n. (114 Thickness of the carapace at the atiterior margin li. 008 Thickness of the carapace at tlio lateral margin 0. 00« Thickness of the plastron neiir the briiljje 0. 015 Thickness of the plastron ninrc centrally (i. OO'J I'onr arenhn in 0"M0. 94 . This species is Iburid in .1 jjreeinsh-brown areniiceoiis rla\' deposit near the Milk River in British America, belonging to the Transition series, probably tiie Fort Union or Lignite epoch. Collected by George M. Dawson, oC Montreal, geologist of the British North American Boundary Commission, near Woody Monnt. Plastomenus costatus, Cope. Represented, in the collections made by Mr. Dawson, by small portions of plastron and carapace, which display distinct osseous, but no dermal scutal sutures. These specimens were discovered together, and are believed to belong to the same individual. The bones are thinner than corresponding ones of the two other species of tortoises described, from the same locality, (excepting at the costal enlargement, which is remarkably prominent and \\ell- detined on the under .side of the carapace. The dense or cement layer of the carapace is thrown into very delicate, but prominent ridges, which run parallel to the axis of the carapace, and occasionally inosculate, or are crossed by a similar ridge rumiing at right angles to them. The sculpture of the plas- tron is similar, but more obtuse and obscure The superior edge of the free border of one of the lobes of the plastron projects beyond the inferior, and is not, as is usual, less prominent than the inferior. Measuremoits. M. 'I'bickness of a costal .at the margin 0. 005 Thickness of a costal at the rib 0.009 Thickness of the free edge of the jilastron 0. 009 'I'he costal bone of this species is much like that of a 7rioin/x, but the character of the plastron refers it to Plastomenus Collected in the bad lands of the Fort Union Cretaceous, south of Woody Mount, near latitude 49°, British America. Associated with this species were the F. coalescem, Comjjuemi/s ogmius, fragments of perhaps Compsemys vidus and Trioni/x vagans, with Dmosauria, Cionodon stenopsis, etc. (See chapter I.) I Plastomknus punctulatus. Cope. Established on a costal bone found in as.sociation with the preceding species, and referred tj the genus Plastomenus provisionally, and with a ])ossibility that it will be found not to pertain to it when fully known. Tliat ucims liii!^ so far only been louiid in tlic Moccnc I'ornuilKtn. 'llir lionc is rather thin, and sufficiently curved to indicate a convex carapace of moder- ate thickness. The surface is marked with (^osely-packed shallow pits w itli- ont material variation of l()rm on the proximal half of the hone. The result is an ()i)Solete sculpture (piite similar to that seen in some species of the genus to which it is at present referred. MeaniDyiiunts. M. Width of the lu.stal Ijoiic (». 02:50 Tliickiios.s of tlic costal Iioiic 0. (!(K!;{ Niiiiilicr of ])it» ill l)'".0U1, (1. Lignite Cretaceous of Colorado; also, several fragments from Long Lake, " Nebraska,' from Dr. H.iyden. ?Plastomenus in.signis, xp. nor. Represented hy u portion of the right hyposlernal l)one of a tortoise about the size of the la.st species, and from the same locality. The specimen resembles, in its sculjjture, such species as the Plasfomenus trioni/choides, and, in structural character, the species ol' Anosiira, but it is scarcely probable that it belongs to either genus. It is flat, and has a narrowed, straight, inguinal margin, at right angles to the fine suture with the hyosternal. The suture with tlu! p()stal)domiiuil is partially goniphosial. Surface dense, polished, marked externally with a reticulate sculpture of narrow ridges separating larger and smaller areas wider than themselves. Inguinal edge thinner. Measurcmentx. M. Length of the hyposternal fore and .ift . 0. 02."> Thitkucss of the hyposterual at frout 0. 004 Pits in 0™.010, six. Lignite Cretaceous of Colorado. TKIONYX, Geoffr Although species of this genus occur in the greeiisand of Cretaceous No. 4, in New Jer.sey, none have l)een discovered in the West below the horizon of No. 6, or the Fort Union fresh-water beds. Dr. Leidy has described a 7'. foveatus from the bad lands of the Judith River, Montana; and 1 have a. This species differs from the T. foveafus, Leidy, in the much narrower interareolar ridges and larger areae, and in their longitudinal confluence at the margins, characters exhibited by munerous specimens. Lignite Cretaceous of Colorado; near the mouth of the Big Horn River, Montana; Long Lake, " Nebraska;'' found at the last two localities by Dr. Hayden. CYNOCERCUS, Cope. Established on a metapodial bone and caudal vertebrae of a tortoise of uncertain, but in any case peculiar, aftiiiities. The caudal vertebrae are not anterior ones, almost lacking diapophyses, but are long and slender, and the articular faces singularly incised. The form had a tail more elongate than the snapping-tortoise, and different from it in details of composition, especially in l)eing of the procoelian type. Associated with the remains of CUdastes, and other saurians, and at a distance of two or three Iiundred yards from the locality of the fossil Proto- stega gigas, were found some vertelirse of a Testudinate reptile, which ap- proaches the type of Trionyx. Cynocercus incisus Cope. The vertebrae have elongate centra concave below, and have well-devel- oped diapophyses. One vertebra has transversely oval articular extremi- ties; in another, they are much less depressed. The former is the more an- 97 lerior, being known as sucli by its larger (iiapophyscs and much smaller artic- ular surfaces for chevron-bones; it appears probable, indeed, that this one has been without these appendages. It is, therefore, from no great distance behind the sacrum. Its position being thus determined, it may be described in detail as follows : As observed, the centrum is elongate and depressed. Tiie inferior sur- face at the cup is flat ; it is then arched upward, descending again to the rim of the ball. The posterior two-thirds has a median groove, which terminates in a deep notch of the ball, which involves one-third of its vertical diameter, and widens backward. The ball is transverse oval, and only moderately convex ; near its upper margin, a small deep pit interrupts its surface, having the appearance of an unusually large ligamentous insertion ; its border slightly excavates the margin of the ball. The cup is a transverse oval, wider below. Its inferior and superior margins are so deeply (but openly) emarginate as to reduce the concavity in the vertical direction very much. From tlie superior emargination, a deep groove descends to below the middle, probably for liga- mentous insertion. The neural canal is subtrilateral. The neural arch is, as usual in this group, deeply emarginate in front, and much prolonged behind. The zygapophyses project beyond the ball, and the arch is contracted in front of them. Its upper surface has neither process nor keel, but is rugose for ligamentous and muscular insertion. The diapophyses have a wide base, and are subcylindric. The surface is delicately reticulate rugose; coarsely rugose on the exter- nal faces of the zygapophyses. There are several small nutritious foramina, the largest being in the bottom of the groove of I he lower face. Another vertebra differs in being rather more slender, and in having an obtuse keel of the neural arch. The pit of the ball is wanting, and the iiifc- rior emargination. The chevron-articulations are larger; and the groove of the cup occupies its middle, instead of its upper half Measurements. ii. Length of tlio ccntrnm (greatest) 0.027 Diameter of the cup, vertical 0.01 Diameter of the cup, horizontal 0. 017 Elevation of the top of the neural arch above the floor of the noaral canal 0. Oi;5 L"ngth of tbe arch on the median line above 0. 02 Width of the arch in front of the posterior zyg.apophysos 0. 012 A metacarpal or metatarsal bone was found near, though not willi, the vertebra;, and probably belongs to the same animal. If metatarsal, it is much 98 stouter than in Trionyx, but is more likely to be a metacarpal. It is about as long as the vertebrjE, centrum and arch together. The proximal end is transversely truncate, compressed L-shaped ; the shaft compresscd-subquad- rate; the articular extremity hour-glass-shaped, with an inferior projection for the insertion of a flexor-tendon. This bone is not that of a marine turtle, but ot a species of riparian or terrestrial habits. Length, 0™.034; proximal diameter, 0'".013. These vertebrae indicate a genus with elongate tail like that of Cheljdra, or probably longer ; but they differ from those in that genus by their procce- lian character. An approach to their incised margins is to be found in Trio- nyx; but in those of that genus, where this character appears, the diapophy- ses are largely developed. The genus is evidently quite distinct from any- thing known, and we await further remains with interest. The species is much smaller than the Protostega gigas, and about equal to the Mississippi Macrochelys. TOXOCHELYS, Cope. This genus is represented by a single species as yet, which reposes on a number of specimens. These indicate a structure in many respects similar to the genus Chclone, but sufficiently different to belong to another genus The mandibular ramus is slender, and has a narrow, flat, alveolar surface. The coronoid process is moderately elevated, and is excavated behind by the anterior extremity of the elongate and deep dental foramen. The cotylus is depressed, and the articular bone ossified; the angle is not produced. The coracoid bone is long and spatuliform, like that of the marine turtles. A fragment of the same skeleton supports a condyle with slender, subcyliiidric, slightly-curved bone attached to one side of it. Were it not a turtle, I should say that these are the extremity of the quadrate, with a slender jugal or malar bone adhering. The slenderness of the mandibular rami resembles the form in Chelydra, but it differs in the absence of the alveolar cutting-edge of the latter. The ]>lialanges are broad and flat, and not unlike those of Protostega. ToXOCHELYS LATIREMIS, CopC. The symphysis mandibuli is very short, and the upper face horizontal. The angle is truncate beliind, flat, and not produced beyond the cotylus. 99 Measurements. M. Length of tlio co.acoid 0.250 WiiilU of tlie coracoiil distally 0.080 Lenstli of the ramus of the inaudible 0. 157 Length of the sym)>hy8i8 of the mandible 0. 031 Elevation of the coronoid of the mandible 0.043 Width of the- angle of the coronoid 0. 023 The axes of the mandibular rami produced unite at an angle of 65°, indicating a muzzle of intermediate length. The size is about that of the existing loggerhead (Careiia caouand). Found by Professor Mudge near the forks of the Smoky Hill River. Fig. 2. — Sketch of the large radiated bone of I'rotostega gigaa, with other elenxMits, as they were uncovered by excavation; size much icductd, drawn on the spot. Nos. I, "Vll, VIII, and IX, costal bones, with the rib-heads looking upward ; X, the coracoid bone ; 5, a marginal bone ; 9 and 10, the lateral a radiate bones; 16, vertebra, with other bone adherent. PROTOSTEGA, Cope. This genus is the type of a new family of tortoises of the suborder Athccce, characterized by the lack of exj^ansion of the ribs into a ])ony roof, 100 or carapace, and the development of independent superficial dermal bones. The dermal bones consist of large plates lying above the ribs, which have no sutural union with each other; of some small vertebral shields on the dorsal line ; and of tbin, marginal bones, which have no sutural union with each other or with the other bones. The vertebras pi'eserved possess ball-and-socket joints, and have flat neural arches, with widely-spreading articular processes. The humeri are flat, and furnished with an enormous deltoid crest. The fore limbs were very long, and formed flippers like those of the marine turtles of the present seas. The bones of the head are very liglit and thin, and mostly united by squamosal or overlapping sutures. The mandible presents the elements usual in the marine turtles, and has no angle. It exhibits a deep pterygoid fossa, and is very light. The constitution of the bones is rather dense, and there are no medullary cavities whatever. The superficial layer is very thin and striate. The bones are all very fragile. The affinities of this genus appear to be largely to the Sphargididce. This family is represented, in our present knowledge, by but one genus and one species of the recent seas. It is one of the most generalized, or, in special characters, the most aberrant, of the order of tortoises, and the dis- covery of an extinct ally, even as far down In the series as the Cretaceous period, is not surprising. The remains preserved belong to a single individual, and include many portions of the cranium, five vertebrae more or less incomplete, the scapular arches of both sides, with the coracoid bones; both humeri perfect, with nine phalanges, ten ribs, one vertebral(?), and ten marginal bones; parts or wholes of four large lateral (!) dermal bones, with five distinct bones of unknown reference. There are also some slender curved bones, which probably pertain to tlie plastron. As the bones were exposed by excavations in the yellow Cretaceous chalk, sketches of their positions and relations were made, which aid mate- rially in the restoration of the animal. The upper layer of bones were those of most irregular form, as cranial and limb bones. Mingled with these, but often beneath them, were the ribs ; while underlying all were the large flat pieces here described as dermal. Adhering to the inferior surface of these was a layer of thin oyster-shells, with parallel striate surface, perhaps Inoceratni. The ribs presented their heads upward, so that, taking all points into con- 101 sideration, there is little iloiibt that the reptile was entombed lying on its back. The texture of the bones is peculiar. There are nowhere to be seen medullary cavities, and the bone is spongy, but very finely so; the tubules at the largest being equal in diameter to an ordinary pin, and generally consid- erably smaller. They are arranged in concentric series. There is no thick dense layer of the bone as in other tortoLses, but an extremely thin one, which is hard, and sculptured on the surface with minute grooves or pits. The tissue of the bone is very fragile, and has si fracture like the mineral inclosing it. Many of the bones, especially those of the dermal skeleton, are extremely attenuated on the margins, being no thicker than writing-paper. In discussing the affinities of this genus, one doubtful point must be considered. The large tlat elements described as lateral dermal bones, are they ossifications of the dorsal or ventral integumentl They were found below all the other bones, and nearly all the ribs laid on them with their heads turned upward. This rendered it probable that the shields were dorsal, and that the animal was entombed on its back; and a coracoid, which was afterward found lying immediately on the largest bone (No. 10), crossed in its course parts of two ribs. This could not have been the case had the shields been ventral. An examination of the shields docs not reveal any conformity to any known type of Testudinate plastron. The bones radiate in all directions, leaving no margins for fore and hind limbs, or for a median fontanelle, still less for suture with each other. Should these bones then be regarded as dorsal, they constitute a charac- ter not previously noticed in the order, but one whose homologue is seen probably in the dermal shield of bony tesselated plates seen in Sphargis. The other points of affinity to Sphargis are the distinct ribs; the thin lamin- iforni jaws with cutting-edges; the quadrate bone with such a strong anterior concavity ; the elevated position of the zygomatic bone ; the form of the humerus. Points of special reseml>lancc to Chelone are : the short posterior superior portion of the quadrate ; the entire edge of the maxillary bone ; the deep dentary. Tlie points in which it diffisrs from both are numcrou.s. They are : the dorsal shields; the marginals; the notched symphysis, etc.; tlic shortened articular end of scapula; the elongate form of the carapace, etc. The constant separation of (he ribs and the shortvertebrae are charac- ters which arc more like those possessed by other reptiles Ihau (liose cliarac- 102 teristic of Testudinata. The presence of dermal dorsal bones is of the same kind. Tlie genus Protostega then belongs near the Sphargididce in the sub- order Athecee, and is in some points to be approximated to the Cheloniidce. Protostega gigas, Cope. There are twelve marginal bones. They are all characterized by their laminar form. The thinnest are those farthest removed from the middle of the sides. They consist of a single lamina, slightly thickened within the margin, producing a slight convexity of the lower side. The proximal part of the bone is an extremely thin plate, with radiating ossification, and conse- quently more or less serrate margin. It extends some distance over the extremity of the rib, whose apex is received into a half-pit or acuminate groove with abrupt termination, about one-sixth the width of the bone from the margin. In following the marginals to the middle of the side, the edge, as usual, increases in thickness. The lower side, becomes more convex, and the upper slightly concave. The edge is acute, with a very open interior entering angle at the middle. The lateral extremities of the marginals are irregular, termi- nating in a double series of closely-packed digitations, which terminate freely, and enter into no suture. The pit receiving the extremity of the rib ap- proaches the margin, which now develops an inferior lamina of bone. This incloses the end of the rib, and thins out laterally in contact with the superior plate. In some, the inner lamina is short ; in others, it is almost as extensive as the outer part of the marginal plate, causing the double appearance when frac- tured. As the marginals thicken, a distinct inferior plane becomes distin- guished, separated from the interior face by an obtuse angle. The upper face near the margin is more concave. In the thickest, the inferior face is also somewhat concave, and the edge quite acute. The lateral extremities consist, as before, of packages of digitations, which easily break out. A single nearly bilateral bone of this series appears to be either nuchal or caudal; but, as it has no sutural connection with any other, it is not easy to determine which it is. Its marginal length is much less than its transverse extent, which consists chiefly of a flat lamina. The marginal part is a little thickened, and bilaterally concave below, and correspondingly convex above. The margin is thin and acute. A few grooves radiate at a distance from the middle toward the margin. The lack of concave excavation of the margin would incline the balanct; in iiivur of the view thai this hone is \\\v caiKlal. t) 103 A very long, gently-curveil bone is probably the marginal extending on one side of the nuchal. It is nearly twice as long as the others, and has an extensive and thin superior lamina. Its ? anterior part is in one plane; but the margin soon thickens, and displays a rather wide infero-external face. It appears to have had an inferior lamina on its posterior half, which made an angle with the face just described. An oval cavity included looks as though designed for the apex of a rib. The variation in the lengths of these marginal bones is noteworthy. I give measurements, premising that a few lines may be added to the extremi- ties of some for lost digitations. Measurements. M. Lenj;tU of the long anterior (11 inches) 0.28 Widtb of the long anterior (some lost) 0. 135 Length of the lateral with the inferior face — 0. 195 W'iclth of the lateral (mnchlost) 0.110 Length of the lateral with narrower inferior face 0. 1!06 Width of the lateral (much lost) 0.115 Length of one with the interior lamina 0. 14 Width of one (soaie lost) 0. 086 Length of a thinner, no inferior plate 0. 10.3 Lengtli of a still thinner, no inferior plate 0. 1S2 Width of a still thinner (broken) 0. i:!7 Length of the thinnest -._ 0. 1()2 Width of the thinnest (nearly complete) 0. 160 ? Caudal length 0.117 'Caudal width 0.150 The shortness of the marginal with large interior lamina is noticeable, as also the same peculiarity in the caudal. As compared with marine turtles, difference is to be observed in every particular. Such are the lack of sutural union; the laminar cliaracter; the great extent of the superior and distinctness of lower laminfE. There is no trace of epidermal sutures visible anywhere. A single .symmetrical plate appears to have belonged to the middle line of the back or nape. It was subtriangular in outline, all tiic margins very thin, and with an obtuse keel extending on the middle line, on the posterior (or anterior) two-tbirds to the apex. This ridge disappears in ? front !)y a gradual expansion The surface is marked by lines of minute pits and grooves, which radiate from the base at the (I) front of the ridge. Length, 0M35; width, 0'".21. The lateral dermal bones preserved, are two entire, and large parts of one. or two others. They have an irregular oval outline, and nrr slightly dished on the inferior surface or that next the ri])s. The u[)[K;r .surface is 104 more convex longitudinally, from the thickening of the bone. The margins are irregular, from the projection of many tligitations. Some of these are broad and flat; others are narrow. They are frequently two deep, and the fissures separating them occasionally extend far toward the middle of the bone. The convexity assumes the form of a low ridge toward one end of the bone. At the point where this reaches the margin, the latter is in all the four plates, thickened, and composed of several layers of packed osseous radii. When found, the ribs laid across these shields, one of them occupying the position of a radius to one of them. These shields are much larger than the marginal bones. Measuremenis. M. Leugtli of "No. 10" (21 iucbes) 0.535 Width of "No. 10"(brokeD) 0.400 Thickacss at the middle 0. 014 Lenjrth of " No. 9 " 0.530 Width of "No. 9" (much broken) 0.350 Thickness at the middle 0.013 The lengths and breadths given are a little below the truth, owing to the loss of the exceedingly thin margins. Turning to the endo-skeleton, the vertebrce deserve mention. There are more or less complete examples of five of these ; in two, both centrum and neural arch, in two neural arch, and in one centrum, are preserved. These have been recognized chiefly by their neural arches, which are separate. They are in form something like an X, the extremities of the limbs carrying the zygapophysial surfaces. The only point of contact with the centrum is a wide process, which stands beneath the anterior zygapophysis, and spreads out footlike obliquely forward and outward, to beyond the line of its anterior margin. Its surface extends nowhere posterior to the surface of the zygapo- physis above it, but a little farther inward. Its outer margin rises ridgelike to the under side of the neural arch, and each one, forming a semicircle, forms the boundary of the neural canal, and, turning outward, forms the inner boundary of the posterior or down-looking zygapophyses. The space between these apophyses is roofed over, so as to produce a shallow zygantrum, which, however, only seems to roof over the deep emargination of the neural arch of the vertebra immediately following. The anterior zygapophyses are often broken away, so that the neurapophysial supports look like the missing pair, when the difficulty ensues that both pairs look downward. The top oi' the 105 neural arch is, in two cases, broad aiul flat; in two others, there is an obtuse keel. The centra, apart from their arches, are puzzling bodies, especially since in the present case, they are somewhat flattened by pressure. They differ materially in size ; one of them being twice the size of the others. The smaller ones are of the ball-and-socket type, and have a deep longitudinal groove on each side. The thicker portion of the centrum forms the inferior boundary of this pit-groove, while a thinner portion, possibly a diapophysis, limits it above. It is, however, thin, and had no great length. There is no sign of chevron bones and articulations, so that these vertebrae may have been cervical. Their bodies are, however, shorter and wider than in those vertebrae of any known tortoise. A groove on the upper surface represents the neural canal ; while a flat area on each side, in front, supports the neurapophyses. The large centrum exhibits the superior groove and antero-lateral platform for support of the neural arch. One end is cupped obliquely, while the other is nearly plane, with the same obliquity and a slightly-raised margin. Its outline is subtriangular. The lower side of this centrum possesses a short keel posteriorly. The sides exhibit no pit, but have a thin edge, which is concave behind the middle, and then turned outward. I can see no articu- lation for a rib. The forms and characters of these vertebrae resemble Sphargis moi'e than anything yet described.' Either the large or the small, or both, must be referred to the dorsnl region ; in this case, the concavity of one extremity is a new feature among tortoises, so far as known. The great freedom of the arch from the centrum is very peculiar; while it is probable that the articula- tions of the ribs were to the middle of the side of the body, and not to the adjacent parts of two bodies, and may have been (see below) to processes or diapophyses. Measurements. M. Length of the modium contniin 0. 0:17 Width of the iiiediiim coutrum 0. 0110 Length between tlie margins of the zygapopb.vses of the mcdinm centrum 0. 0(>0 Width between the anterior margins of fhe zygapophyses of the medium centrum 0. 070 Width between the posterior margins of the zygapopliyscs of the medium centrum 0. 047 Width between the anterior bases of tlie arch 0.070 Width of the arch at the middle 0.028 Lengtii of the arch at tlie middle (*• O-JO Width of the posterior zygapophyses of No. 2 0.048 Width of the arch O.O'i'J ' See Teuiniinck and .Schlegel Tauna Japoiiie.a, Reptiles, Tab. 1-4. 14 0 106 M. Length of the arch 0.025 Length of the anterior foot (oblique) — 0. 020 Length of the ceutnim of the large one 0.060 Width of the centrum of the large one 0.094 Width of the neural canal of the large one 0.017 Ten ribs were recovered. These are slender and rather flatter than in most reptiles, but without the peculiar form characteristic of tortoises and turtles. They are most expanded proximally; the bone spreading into a lam- ina from the tubercular region, extending laterally and proximally some dis- tance beyond the head. The superior plane of this expansion is continuous with that of the rib, and is flat ; the head of the rib therefore turns down- ward and inward from it, to join the vertebra. Now, the extent of the inner part of the lamina is such that, were the head articulated to any of the cen- tra discovered, the laminae would interfere or overlap. They may, therefore, have been articulated to diapophyses. The expansions are serrato-digitate on the margins, and exhibit radiating grooves and ridges in some places on the superior aspect. The lengths of these ribs are not so great as the pro- portions of some of the other bones would indicate. Measurements. M. Length of "No. VI "(16 inches) 0.510 Width at the head 0.140 Width of the head 0.040 Width at the middle 0.055 Width at the extremity 0.040 Length of "No. II" 0.300 Widthof "No. II "just below the head 0.100 Width at the middle 0.037 Lengthof "No. IX" 0.380 Length proximal to the head 0. 060 Width at the middle 0.080 In the rib "No. II," the head is turned obliquely to one side, indicating that the rib diverged at a strong angle from the vertebral column ; in fact, not more than one of 45°. This is, then, an anterior or posterior rib ; probably the latter, since the shell is usually expanded chiefly in that direction. All the ribs are flat above, and convex inferiorly. Both sides of the scapular arch are complete, except the sutural portions of the coracoid and scapula of one side. The scapula and procoracoid make a very open angle with each other, both being stout; the scapula the longer, with grooved sculpture at its j^roximal end. The procoracoid is a little the shorter. The glenoid cavity and coracoid suture are almost sessile at the 107 union of the scapula and procoiacoid. The coracoids arc very elongate, almost equal to the ribs, and not stouter except at the extremity. It is expanded into an oblique head proximally. The shaft is flat; one edge thick- ened or truncated; the other thin. The distal portion is scarcely expanded; being more slender than in any recent Testudinate known to me. Measurements. M. LengtU of the scapula to tlio glenoid cavity 0. 213 Width of the scapula proximally 0.045 Length of the procoracoid to the articular surface - 0. 106 Width of the procoracoid distally 0.060 Length of the coracoid 0. 400 Width of proximally 0.080 Width of medially 0.047 Width of distally 0.080 The elongate coracoid resembles most, among recent Chelonians, the marine genus Chdone; while the sessile glenoid cavity and short procoracoid with open angle are entirely different. In these points, this genus is more like terrestrial forms, as Testudo, or less like Emys. Both humeri are entirely preserved. They appear to have been some- what flattened by pressure; but, when unaltered, they were, no doubt, flat, with stout proportions. They have a globular head, with an immense trochanter, which projects much beyond it proximally. The shaft is then much con- tracted, and expands again distally to the broad and very convex articular extremity Opposite the narrow part of the shaft, the small troclianter appears on the inner side, forming an elongate ala. Tlie long axis of the liumerus is not straight; the proximal and distal portions making an angle of 110° with each other. Measurements. M. Total length of the humerus (1 foot) straight u. 3U0 Length of the humerus from the head 0.290 Width at the head , 0. l.-SG Width of the head 0.073 Least width of the shaft 0.07G Greatest distal width 0. VM Length of the basis of the little trochanter 0. Q80 Thickness at the shaft 0. 0:U The flatness of this element, and situation of the large trochanter in the general [dane, are characters of the Sphargididce. The great constriction medially and expansion of both exircmilies romiiul one of tlie niosnsaiu-oid humerus. 108 Of bones of the fore-arm, there may be one ; but the bones next in size to the humerus look more like metacarpals or metatarsals. Two of them were found together in position; and their relations were not like those seen in the fore-arm of sea-turtles. They measure over seven inches in length, and are strongly concave on their adjacent sides. One of them is slightly concave on the outer side ; the other convex, the convexity being at two-fifths the length from one end. The ends of both are a little expanded ; and one end of one displays a double or trochlear extremity. The same end of the other is injured by pressiire. A still larger metacarpallike bone is relatively more expanded at the ends. The articular surface of one of these is wide at one end, and much narrowed at the other. The smaller bones, undoubtedly phalanges, are six in number. They are quite slender, a little expanded at the ends, and flat. Measurements. \ M. Length of the largest • 0. 1C5 Width of the largest at the extremity 0. 0C5 Width of the largest at the middle 0.032 Length of the longest of the pair 0. 180 Width at the extremity 0.C50 Width of the shaft 0.027 Length of the phalange 0. 132 Width at the extremity 0.032 Width of the shaft 0.018 Thickness of the shaft 0.011 These measurements indicate, for the fore-limb, a total length of 4.52 feet (1".347) if proportioned as in Chelone; this would give an expanse of 11.3 feet. If, however, it was constructed on the plan of Sphargis, the expanse would be nearer seventeen feet. Several instructive cranial bones were preserved. These are the maxil- lary and distal part of the dentary of the left side ; the posterior part of the left mandibular ramus ; quadrate bones and adjacent pterygoids and squamo- sal, one side with the columellar plate; right postorbital bone and part of the left ; also, some probably hyoid elements. The maxillary bone and the dentary present a considerable extent of the alveolar margin. This is remarkable in being thin, sharp, and elevated; without horizontal portion. The former bone is but little incurved to the premaxillary suture ; its anterior outline is elevated and vertical, the nostrils entering opposite the probable middle of the orbit. The palatal plate of the maxillary has no great antero-posterior extent, so that the inner nares arc 109 opposite the anterior part of the orbit. The latter presents only the anterior and inferior outlines in the specimen. The part of the maxillary below it is very narrow, and weaker than either Sphargis or Chelone. The cutting-edge has a very open sigmoid flexure, the suborbital part being turned inward, the anterior part a little outward. The osseous rim of the orbit projected out- wards considerably beyond the plane of the maxillary anteriorly. The dentary hone is very deep anteriorly, and, like the maxillary, is a thin, vertical lamina. The lower anterior angle is truncated by an acute, concave margin. This is the anterior extremity of the symphysis. This suture occupies the inner face of a triangular area, which extends but a short distance on the lower margin of the ramus, and then passes upward and backward for a short distance on the inner face of the ramus. That portion above the symphysis diverges outward; thus producing a deep notch at the symphysis, as though designed to receive a beaklike projection of the pre- maxillaries. The cutting-edge has a slight sigmoid flexure, corresponding with that of the maxillary ; it rises into a projecting angle. The posterior part of the ramus displays the cotylus, and, in front of it, a deep, long fossa behind the articular bone. There is no angle nor coronoid bone, as in all marine turtles. The superior margin of the dentary is thicker posteriorly than in front; and its outer wall is produced backward as a thin lamina, covering the surangular almost to the posterior edge of the ramus. The angular is, as in recent forms, a narrow, wedge-shaped piece below the dentary and surangular. The posterior edge of the surangular projects behind the dentary, and exhibits an acute, convex edge rising forward. It supports a small part of the articular cotylus on its inner face. Most of this portion occupies the extremity of the articular. The latter sends a stout lamina obliquely upward and forward to the lower posterior part of the dentary. The quadrate bones are of peculiar form. They exhibit the usual jJoste- rior curvature above, with a shallow funnellike fossa for the tympanic cavity. It presents two strong ridges anteriorly, an inner and an outer, which inclose a deep, vertical concavity. The inner exhibits the suture with the pterygoid bone; the outer, with the zygomatic. The superior border of the quadrate within the squamosal is massive, and not inflated. Its surface is thickest where the usual articulation with the opisthotic exists. The posterior hori- zontal is short and deep. Tiie transverse part of the bone which support^ inferiorly the exterior i)art of the condyle is thin, and disappears above to the 110 antero-posterior portion. From its middle upward, it supports the zijgomatic. The latter has no great extent anteriorly to its malar suture ; and its inferior margin arches high above the line of the condyles of the quadrate. ^\i& pterygoid bones are subtriangular in outline, with concave sides, an emarginate base, and a very obliquely truncate apex, which articulates low down on the quadrate bone. Both margins are thickened and rounded ; the superior as a boundary of the foramen ovale. The posterior margin of the platelike columella overlaps it on the inner side, deeply notching it ; on the outer side, the suture is zigzag and transverse. The superior part of the bone is produced like a flat rod, and, at its end, exhibits a squamosal suture for union with what is, in the snapper, a postero-inferior rod-like prolongation of the columella. No such process of the columella appears to exist in this species. The columellar plate is half as large as the pterygoid, and exhibits the obUque suture in front for the descending lamina of the parietal. The postfrontal hone of the left side is preserved entire, and the inferior portion of that of the right. The inferior margin for the malar is the longest, and is straight. The orbit is excavated in part from its anterior margin ; while the supero-posterior is a continuous curve. The inferior suture is a groove, whose inner bounding wall is convex, but rises past the straight outer to an inner ridge, which probably approaches the ectopterygoid region. A large sutural face for the zygomatic exists at the lower posterior angle, and an elongate one above for the parietal. The inner face is concave, indicating a large temporal fossa, as in Sphargis and Chelone. Two bones, of opposite sides of the cranium, are either those portions of the pterygoids which bound the temporal fossa below in front, or those portions of the maxillary bounding the palatine foramen. As the free margin is much thickened, they are probably the former. Their inner, or thinner, lamina is marked for squamosal suture with other bones, perhaps columella and palatine. Measurements of the cranium. M. Depth of the preniaxillary sutnro of the maxillary 0. 060 Length from the premaxillary suture to the iuner nares 0.008 Depth of the maxillary below tho orbit 0.035 Depth of thedentary at the symphysis 0.078 Depth of tho notch of the deutary at the symphysis 0.044 Depth of the dentary behind the symphysis 0.09,5 Depth of the deutary at the coroiioid region 0. 085 Depth of the ramus at the front of the cotylus U.OGl Length of the pterygoid fossa of the cotylus 0. OGO Ill M. Length of the cotyloid fossa 0.070 Length of the postfrontal on the inferior suture 0. 195 Depth of the postfrontal at the honndary of the orbit 0. 13G Thickness of the postfrontal of the lower suture 0.019 Length of the postfrontal from the orbit (^oblique) 0. 115 Length of the right quadrate 0. 140 Width (antero-posterior) 0. 110 Width of the condyle 0.0G4 Length of the right pterygoid superiorly 0. 155 Depth of the right pterygoid at the inner columeUar angle 0. 100 Leegth (oblique) of the columella 0.085 Restoration. — Better materials exist for the restoration of this species than is usual in the case of most extinct Testuclinata. The cranium was 0°.50, or 24f inches, in length. If the neck and carapace were related to it as in the genus Chelone, the total would be as follows : Cranium 24f Neck and carapace 1391 Total, 12.83 feet lC2f an extent not far from the expanse of the flippers above given, viz, 11.30 feet. The shortness of the cervical vertebrse indicates that the proportions of the neck were not dissimilar to those of the existing marine genera. The flippers were probably similar to the same ; of the hind limbs, nothing can now be stated. The shortness of most of the ribs, considered in connection with the length of the marginals, is remarkable. Thus, the longest rib measures O^.Sl, or 16 inches; width of lateral marginal beyond apex of rib, 2.25 inches; width of vertebra, 3 inches, which is, however, covered by the expansion of the rib, included in this case in the length, 16 inches; total width of cara- pace at middle, 36^ inches; length of carapace, estimated from cranium, 118 inches; or, width, 3 feet i inch; length, 9 feet 10 inches. An outline, twice as long as wide, is justified in measure by the size, especially the lengths, of the marginals, which, if placed end to end, would measure on one side of eleven pieces, if each were as long as the median, S-.O inches X H = 7.8 feet. Some of the posterior raargiijpls are shorter than 8.5 inches, while some of the anterior appear to be longer. The length, 8.5, may then be take.i as an average. But they formed the circumference of an open arc, so the axial length of the carapace should be placed at a lower figure than the above. Tliis proposition may be offsetted by the fact that the marginals were not united to each other, and exhibit no indications of contact. The length of seven feet for tlie cara- pace is not, llioi), too much, and, estimating from the size of the head, is too 112 little. We can then safely conclude that the carapace of this turtle is more elongate and narrowed than existing forms. Thus, in Chelone mydas, the carapace is six-eighths as wide as long. It remains to discuss the question of the age of the specimen. It migkt be objected that the absence of carapace, and the radiate character of the margins of many of the bones, indicate that our type-specimen is young. To this it may be replied, first, that it is in the (?) sternal bones unlike the j'oung of any known type, when certain of their bodies do at all times exhibit smooth margins as boundaries of the points of exit of the limbs ; moreover, it is possible that these plates were dorsal ; secondly, the superior or inner extension of the marginals exceeds that of any known tortoise in the adult condition ; thirdly, the articular bone is ossified ; fourthly, separate ribs should be discovered among extinct tortoises as an adult character, on theoretical grounds, the more as it exists in one recent genus {Sphargis, fide Wagler). Distrihiition. — This fossil was found near Fort Wallace, Western Kansas. It was entirely recovered by excavating. The edges of one of the large bony shields were seen projecting from a bluff near Butte Creek, and was followed into the chalk-rock with pickax and shovel with the re- sult already indicated. The large bones were ex- posed in an entire condition, but were mucii frac- tured in the attempt to lift them from their bed. Though carefully packed, the transport of fifteen hundred miles still further injured them, and the portions described were reconstructed of over eight hundred pieces by myself. One of Fig. 3. — Costal bouos of a younc ,, , i, ii • , -, r\n • Testudopoiyphemm from heio^; nat- t^^ bouy plates was broken mto 108 pieces, ""•"i"*^"- the ribs into 183, the marginals into 146, &c. A second species oi' Protostega^ appears to have existed during the Cretaceous period, as indicated by a humerus from near Columbus, Miss., sent by Dr. Spillman to the Academy of Natural Sciences. With it were received bones of the mosasauroid Platecarpus tympaniticus. Cope; and Dr. Leidy, who described them,^ regarded all as belonging to one animal. On this basis, he ' Proceedings of the American Philosoiiliical Society for 1871, p. 173. 'Cretaceous Eei)tiles of North America, p. 42 : Smithsonian Contribntions, 18C4. expressed the opinion llmf ibc fore-limbs of the Pylhonomorpha were natatory. Thai tliis view wiis correct I provful by study of the skoh'toii of Clulastes pw- python; and it now appears that the tore-limbs of the latter wert; the (irst ever described. The hnmenis of the Mississippi Protostega (see Lcidy, /. c, I'l. viii, Figs. 1-2) is more elongate than that of tlie P. gigas, is less contracted medially, and the (great trochanter or) deltoid crest is longer and stouter. This I called Protostega tuberosa} (Proceedings of the American Philo- sophical Society for 1872, p. 433.) I also pointed out the existence of a third species, as distinguished by the form of the humerus, in the green- sand of New Jersey, which had been referred by Leidy to the "great Mosasnurys^ From this specimen, Leidy inferred the natatory character of the limbs of Mosasaurus. The New Jersey species I called Protostega neptun'ia. A name had l)een already proposed for it; i)ut, as it was unac- companied with specific or generic description, I did not adopt it. This was d(me in accordance with the well-known rule that such names without descrip- tion are useless in nomenclature; and I conceive it to be not only a privilege but a duty to ignore names put forward in this manner. The custom of giving generic and specific names without corresponding diagnosis has only recently been introduced, and has no claims to respect. It will, if continued, render the science of paleontology .accessible only to a i)riv- ileged class, who may have control of museums, or who can adopt' a nomadic lite in traveling from one museni to another. In the case of I lie V rotoMega nvp- luiiia^ had Professor Leidy, who figured and described the specimen for th(! lirst time, adopted tiie name already given, 1 should have WM bound lo em- ploy tlie latter, ascriljing it to Leidy as tlie author; but, as he lefl il among liu; synonymy of the Mosasauroids, I hav(^ thought il aiUisalile to follow Inni. PYTHONOMORrHA. TIh' characters which distinguish this order are the following: 1. The (|iiadrate bone is attarlK^d to the cranium by a giniflymoid articu- lation, admitting oi' free movement. ^1. The ribs an; attached by simple articulations lo sini,de arlicular i'acets oi ditipuphyses springing from the bodies of the vertebra;. ' I iiuiilvcrtciitlv wrote I'Uitenirpni tiihiroKiin in tlii' abovi^ essay. If) V 114 3. There are two pairs of limbs, whicli form packllcs, having the elements arranged in one plane, and incapable of rotation or Hexure on cacli other. 4. There is no sternum. ' 5. The scapular arch consists of scapula and coracoid only. 6. There is no sacrum. 7. The pelvis consists of slender claments, of which the inferior are nearly transverse, and meet without uniting on the middle line below. 8. The opisthotic bone projects free from the cranium as tlie suspenso- rium of the quadrate 1)one, and is supported and embraced l)y a pedestal pro- jecting from the cranial walls, composed of the prootic in fnjnt and the exoc- cipital behind. 9. The stapes lies in a groove on the posterior side of this suspensorium, and is produced to the os quadratum. 10. There is no quadrato-jugal' arch. 11. The parietal bone is decurved posteriorly, forming the cranial wall in front of the prootic. 12. The brain-chaml)er is not ossified in front. 13. The squamosal bone is present, merely forming the posterior part of the zygomatic arch. 14. The mandible is composed of all the elements characteristic of rep- tiles: the articular and surangular distinct; the angular represented l)y its anterior portion only ; and the coronoid present. 15. The atlas consists of a basal and two lateral pieces only ; the odon- toid is distinct, and is bounded by a free hypapo|)hysis, besides the hypapo- physis of the axis. 16. The caudal vertebrte support chevron-bones. 17. The teeth possess no true roots. The free quadrate bone and simple costal articulations at once refer this order to the Strcptostylicate division of the Repfi/ia, which cml)raccs only the three orders of Lacertilia, Pythonomorpha, and Ophidia. There are several characters, however, in which it resembles some orders of one other i)rimary group, viz, the Synapfosauria, which embraces the Sauropterygin, Testut/i- nata, and Rhynchoccphalia} In the al)sence of sternum, it resembles tortoises and Plesiosaurs, and differs from lizards. It resembles the tortoises in the; ' See Procecdiugs of tbo Aiiioiican Association for tUo Advaiicuineut of Sciouce, vol. XIX, p. 2;i3, 1870. 115 posterior decurvature of the upper portion of the quadrate bone, which thus partially incloses the auricular meatus in a manner not seen in lizards and serpents. To the orders of the oti^^r primary divisions IcIitJn/opteri/g'ui and Archosnur'ia, as the Ichthyosauridce and Crocodilia, there; is not the least affinity. The remaining characters above enumerated ally the Pythonomorpha to both serpents and lizards. A's there are many Laccrtilla without limbs, and some serpents with them, their presence in this order is irrelevant in this connection, especially as the arches supporting them are most like those of tortoises and Plesiosaurs. In the absence of sacrum, it resembles both the associated orders, though the same character is universal in serpents, as the presence of limbs is general in the lizards. The manner in which the opis- Ihotic bone projects from the embracing bones is a decidedly ophidian feature, while the production of the exocci[)ital and ])ro5tic is lacertilian. The posi- tion of the stapes and absence of quad rato-ju gal arch arc characters common to both orders. The lateral decurvature of the parietal is a character of th(! Ophidia, and not of the Lacertilla; while the failure of this l^onc and the frontal to complete the cranial chamber in front is a lacertilian feature. The composition of the jiosterior part of the lower jaw is like that in the lizards in the distinctness of the articular and surangular Ijones ; in the presence of chevron-bones, it differs from snakes; the atlas and axis are those of both snakes and lizards, and entirely different from those of CrocodUia. In the absence of true roots of the teeth, these animals differ from all LacerlUki, and more nearly resemble, without being identical with, the OpJiidln. Thus it is evident that the Mosasauroids and their allies represent an order of reptiles distinct from any other, and I have called it Pythonomorpha, from those points in which it resembles tlx; Opiiidia. There are innny other eliaracters common to all the known species of this division, which arc not pn)lial)]y of ordinal cliaractcr, and wliieli T \\\o- ceed to enumerate. Among tliein will be found some known elsewhere in the Oplddia, and others which relate them to lacertilian groups. Craniu7n. The skull, ill tlie known species of this ordfM-, is wedge-shaped, and generally elongate. Posteriorly, it presents postfronto-squamosal and paricto- qualrate arches ; in some spccif^s, also, a malar arch is thouiriit to exist. Teeth. — These exist in a single row on (he dentary, palatine, and IIG itiaxillary hones, aiKi in two rows on llio prcmaxillary. The crowns are simple, and offer various modifications of" the cone. Their dentinal sul)stance is confined to the crown, and is attached, at the base, to a pedestal of ostein, which occupies the alveolus of tlic jaw, and projects al)ovc it. This is stated, by Cuvier, to be an ossification of the tissue surrounding the circu- latory vessels and nerves which penetrate to the crown, and which remain unossified in serpents and most fishes, but are surrounded l)y true dentinal roots in most vertebrates of the land. Hence, the teeth, in this order, do not possess tru(; roots. The crowns are covered witli enamel, and their forms indicate the carnivorous habits of these reptiles. The premaxillari/ is a narrow, simple element, one-half of a cone anteriorly, and much attenuated posteriorly, sejiarating the maxillaries above by the widtli of its spine only. Its extremity projects considerably beyond the latter. The antcM-ior extremity bears two teeth on each side in tiic known species. The maxillary bones are widely separated on the palatal surface, in front, by the vomers; behind, l)y the nares and palatine bones. They termi- nate in a narrow j)rocess behind, whose extremity is broken in the specimens at my disposal, Init which may have supported a malar arch, probably slender, as in the dolphin.s. The nostrils are linear and superior, and separated by a septmn composed of coossified na.sal and frontal bones. Tlie nares extend to a point in advance of the anterior margin of' the orI)it. The prefronlals are largely developed, and margin the posterior part of the nares. In many species, their posterior exterior margin projects strongly in tlie plane of the muzzle, and has caused the orbit to be horizontal, and the range of vision vertical, as in some aquatic serpents; while, in others, it is decurved, as in land-vertebrates. The frontal is a wedge-shaped, flat bone, and presents lateral descend- ing alae medially. The post-frontals are large, flat, and prominent, and project beyond the process they send, posteriorly, to join the squamosal. Posteriorly, they embrace between them a broad, rectangular jn-ocess of the parietal, which, in Clidastes, contains, near its front suture, the })arietal fontanelle. In Platccarpus, the foramen is, usually, in or nearer to the suture. The parietal lias two broad lateral wings, which advance on the frontal, and form posteriorly the broad anterior margin of the temporal fossa. The |)ari('tal crests are separfited by a plane whicii is narrowed, or Ihey unite into 117 a median crest po^ti-riorl}'. Two aulero-supcrior ijrojcctioiis ol' the sii|)ra- occipital embrace the parietal on each side below fhe crest; wliilc il is over- Ij lapped, just below, by Ihe anterior extremity ol' the pioiitie. l^his does not \^ extend solar lorward as tiie siipraoccipital. In I'ront ol", and below, this point, the parietal is deeurved, and tbrms a considerable part of the lateral wall of the cranium, tliongii with but moderate antero-posterior extent. The lateral wall extends to the body of the sphenoid, where extensive sutural surface has received if. I can find no suture crossinsi; it; and it is ap|)arently all alisphenoid or all parietal. A [)art of the parietal is, however, undoubt- edly deeurved in front of the alis[»henoid. The structure is quite as croco- dilian as ophidian in this point. The postero-lateral angles of the parietal s(;nd the parieto-quadrate arches to the o[)isthotie. which sends an ascending process to meet tho parietal, as in lizards. It dill'ers from most of tlies*; in the j)resence of an intermediate i>one, which has been observed l)y Mar.-.ii, and which \\iiuld a[)pear to Ije a dismemljerment of one of those with which it is in contact. TIh! anterior ala of the prootk overlaps the alisphenoid largely. Its posterior lamina may, or may not, meet the expansion of the exoccipital on I he upper face of the sus|)ensoriuni. Interiorly, it is in contact with the outer and posterior base of the sphenoid. The supiaoccipltdl is roof-shaped. The posterior extremity of fhe parietal rests npou it, sending lateral aniies to tlui opisthotic, as in most Lacerlilla. The exoccipital is distinct, and bears a very small segment ot" tiie occipital condyle. The opislhotic stands obliqnely upward and t<)rward, and furnishes a glenoid cavity for the articulation of the (piadratum. It lias a process, directed upward and forward, which occupies a concavity on the inner fiice of the .squamosal, which has the same direction. The squamosal is a subrhondjic bone in a vertical plane, and is flat below, and proximally presents a longitudinal external angle; disfally, it is slender and [)rolong(!(i, and receives the posterior process of the post-frontal. The hasioccipital presents a strong transverse condyle. It is a mnssivc bone, and presents infero-laterally two ])owerful processes, which diverge pos- teriorly, and present l)road, rugose, ovate tiu'cs of insertion. There is an obtuse keel on the middle line l)elow, which bifiircatcs posli'riorly to eacli 118 of" the hileml processes. The distal portions of these processes are over- lapped by corresponding ciiplike processes of the basisphenoid. Tlie basisphenoid is distinct from the basiocc-ipital, and undrrlaps the latter almost to its middle. It is longer than l)r()ad, and sends two processes latero-anteriorly to support the pterygoids. These are not so long as in most lacertilians. Latero-sujieriorly, it presents a broad surface, on each side of the brain-case, for support of the upper side-walls. Postero-externally, it supports the prootic. It thins out anteriorly, and overlaps the alisi)henoid. The suture for this bone widens anteriorly; inwardly, it is elevated into a low crest of the sphenoid. The lircsphcnoid appears to have been distinct ; its base was small ; it is readily lost, and I have not seen it. Tiie floor of the cranial cavity indicates that the medulla oblongata [wssessed the downward flexure characteristic of reptiles ; but it does not take |ilace till the middle of the length of the basioccipital is reached. The posterior margin of the sphenoid is marked l)y a deep pit; its median floor is a transverse elevation ; it then descends again, and terminates in a deep longi- tudinal groove. The roof of the brain-case is marked on the parietal bone by two obtuse divergent ridges, which leave its posterior margin and embrace the fontanelle. The grooves for the olfactory pedicels are narrow and well separated, but they unite and are entirely inclosed by inferior processes of the frontal bone, as in serpents and Varani. These ridges then separate, and leave the bulbi exposed below. Behind and between the narcs, the median ridge again appears, separating two strong grooves. The vomer is divided, and is composed of two slender compressed bones in contact. The imlaline hones have a short lateral union at their anterior end with the maxillaries, and possess a great extension posteriorly, lieing separated from tlie quadrates by the short pterygoids only. They are free on both sides behind the maxillaries, and are flattened either transversely or vertically, or both,- and support a series of strong teeth, generally similar to those of the jaws. Near their posterior extremity, they send outward and forward a strong and generally long process, the distal connection of which is uncertain. These bones are the pterygoids of Cuvier. The true j^terijgoids are rather short, compressed bones, which are united by suture to the borders of a con- 119 r.avity oi' the palatine. Tlicy arc toothless, and have no sutural connection with the ossa quadratu. They present no sutural iiicet for a columella; hut Golclfuss and Marsh believe that the latter element exists. I have not seen it. The OS quadratum is a stout bone, and one of the most uniiormly pre- served among the bones oi fossilized individuals. In general, it forms a halt- disk ; the convex border thin, one side concave, and the posterior border thick- ened. The proximal end is produced backward beyond the line of this border, forming a hooklike process, which is dccurved, nearly inclosing the auricular meatus. Just anterior to the latter, on the inner face of the thick- ened portion, is a i)it, which received the end of the stapes or stapedial carti- lage. The vertical plane of the inferior or mandibular condyle is oblicpie to that of the superior. The superior extremity of the us iiuadratum appears to have had consid- erable motion on th(! opistliotic. Its extent is so much greater than that of the cotyloid or glenoid cavity, applied to it, as to indicate a gliding motion, especially as it constitutes an extensive arc, possessing grooves of attachment for articular cartilage throughout its Icuifth. This arc is ])ent or curved in the horizontal plane, which would result in a twisting of the os quadratum round its long axis, should the motion I suggest have taken place. Such a twist would throw the proximal portion of the ramus of the jaw outward, a motion quite necessary to the horizontal flexure of the ramus at the splenial articulation, which no doubt took place in swallowing any large object. The extent of this outward deflexion of the articular, coronoid, &c., portions of the jaw, was measured by the outward concavity of the proximal end of the quadratum. Thus, this is least in M. depressus, and greater in 31. dekayi and 3L maximus (see cuts. Fig. 48); the great projection of the external angle in lAodon gave that species an excessive power of dislocation, and the same peculiarity in Clidastes was followed by the same effect. As the development of processes and ridges on the ossa quadrata differ in the different species, they may be named as follows : Tlio proximal articu- lar surface extends over the internal angle and over the upper edge of the ala, forming the alar 2>rocess (see plates). Below the, meatus and knob, on the postero-extcrnal margin, there is a ridge, which terminates in a process in some species, to be called the median posterior ridge. In some, a ridge rises from the outer angle of the; distal articular face, extending outside the ridge just- 120 mentioned, toward the pit, called the distal internal longltudmal. In Cront of this, on the inner face of the quadrate, behind or near the origin of . 221) that it possesses six such verteline. I'rofessor Marsh's statement and eouseriuent sniiposition that he lirst determined the uumher of cervical vcrtebrie in the genus (.7ii7uste are the result of a misappreheusiou. 125 portion of a disk. In sninc jrciirni. it is dcpply emarginato, as in LacertUia; l)iit it is usually entire, as in Sauropteri/giu. 'Vhv liumcriis is a small bone, exceedingly wide in ('liddstes and Platc- carpus, and narrower in Llodoit. It is wider distally than proxinially, lias a Hat shaft, and presents no condyles, l)ut elongate articular surl'aces only. The radius is also a wide l)one, especially dilated at its distal and exterior border. The ulna is nuieh less expanded ; the extremities being subecpial, and tlie shall contracted, l»ut flat. The carpals are small, ilat, and lew in number; they are sui)r()und or hexagonal in outline. The phalanges, meta- carpals, and metatarsals are llattened near the ear|)us, l)ut soon become less expanded and more cylindric at the extremities and at the shaft. The term- inal ones are flat. The ]>elvic elements arc slender, and the inferior but loosely-united on the middle line below. The ilium is the longest, and is cpiitc attenuated above, and witliout immediate contact with a vertebra. The pubis is clavate and flat; the v.'ider portion next the ilium, and pierced with tin; tbramen observed in LacertUia. The ischium is broader, and has an angulate poste- rior outline. The femur is equally or more slender than tlie humerus (see the plate oi' Flatecarjms crassartus), and, in Liodon, resembles it in form. It is Hat, without condyles, wider distally, and with a trochanteric tuberosity at the proximal end. The fil)ula is a very wide bone, sometimes constituting three-quarters of a disk. The tibia is, like the ulna, a more slender bone than its companion, with contracted shaft, and subequally-cxpar.ded extrem- ities. The phalanges much res('nd)le those of marine turtles, and the pes and manus are of a less rolnist type than in any other order ol' marine p'ptiles. jtj/inities. The significance of the ordinal characters lias been already pointed out. There remain a iiund)erof peculiarities, not certainly of ordinal value, which are, nevertheless, necessary to consider in estimating the relations of these reptiles to others : 1. The form and position of tlie coronoid bone are those seen in eryci- !i)rm serpents. 2. The articulation of the sjjlenial with the angular is only paralleled in the pvllionoid and allied seiiiciits. 126 3. The extensive freedom of the palatine is less complete than that of the same element in the Ophidia, and much more so than in most Lncerlilia, resembling, in this respect, the Varanida. 4. The close articulation of the parietal with the supraoccipital is seen in the serpents and the amphisbfcnian section of the lizards, but not in true lizards; wliile the supraoccipital crest is a character of serpents, not of lizards or saurians. 5. The presence of fronto-parietal fontanelle is very general in Lacertilia and various extinct saurians, while it is unknown in serpents, crocodiles, and other groups. 6. The parieto-quadrate arch belongs to several groups of saurians and the Lacertilia, but not to serpents. 7. The squamosal bone has a similar distribution among reptilian orders. 8. The firm attachment of the maxillary to tlie other bones has the same significance. 9. The want of sutural symphysis is seen in snakes, the varanian lizards. Ichthyosaurus, &c. ; but not in Lacertilia generally, Testudinata, Sauro- ■ pterygia, or Crocodilia. 10. The simple premaxillary is general in the streptostylicate orders, and uncommon in the others. 11. The underarching of the olfactory lobes by frontal laminae is char- acteristic of some lizards (the Varani) and of all snakes. The above characters are of very unequal value, and may, in many cases, be departed from by forms hereafter ihscovered without invalidating their ordinal relations with the Mosasauridce. As a conclusion, it may be derived that these reptiles are not nearly related to the Varanidm as has been supposed, but constitute a distinct order of the streptostylicate group ; that they are primarily related to the Lacer- tilia, secondarily to the Ophidia, and thirdly to the Saurop>terygia ; that they present more points of affinity to the serpents than does any other order ; and their nearest point of relationship in the Lacertilia is the Varanidce or Thecaglossa. Experience in paleontology has shown that generalized orders have been the predecessors of the special groups of the existing fauna. The structure of the Pythonoinorpha, which has so much in common with orders well dis- tinguished from each other, offers a hint of the character of the primary 127 group from wliicli the latter have spninij. That tliis order is not tliat unknown type is clear; !)ut the indication of alKnity to it is equally unmistakable. Restoration. The proportions and appearance of the Tythonomorpha can be determined from the remains which have been jjrocured. The body-cavity is more elongate than in any group of lizards and sauriahs, excepting the Amphis- h(enia, l)ut not so long as in serpents. 'J'he tail is excessively long and flattened. The head is also long — in some genera, as Clidastes, very slender, and always flat, with the eyes nearly vertical. There is no distinction between neck and body, but a contraction behind the head. The limbs arc very small for the size of the animal, forming broad paddles, with but little peduncle; the hinder limbs well behind tlie ribs, and often smaller than the anterior. The general effect of the more slender of llicsc animals was that of gigantic eels, or some of the snakclike lizards of the present lime, so that they are veritable sea-serpents of the Cretaceous ocean, and would doubtless be described as such were any perchance to be found to be still in existence in the depths of modern oceans. Several peculiarities affecting the appearance of these animals may be derived from the peculiar articulation of the lower jaws. The position of these articulations in advance of the pharynx indicates a baggy extension of the gular walls, to permit the passage of large bodies between the jaws to the (Esophagus. This had, perhaps, the appearance of the posterior part of the pouch of the pelican. This arrangement necessarily requires that the larynx should be, as in the serpents, in the middle or anterior part of the mouth ; for, as in those animals, the delay involved in deglutition would cau.sc suffocation were the glottis immediately below the descending mass. T'his structure requires another, namely, the anterior position of the tongue ; and this organ, unless very small, would have to be received into a sheath beneath tlie larynx and opening anterior to it. Ensheathcd tongues, among reptiles, tend to become cylindric in proportion to the completeness of the sheathing, for obvious mechanical reasons. It is almost certain that the I'ytliononwrplia had tongues of this kind ; for their nearest living allies on l)()tli sides iiave them, viz, the serpents and the varaiiian or thecagloss lizards. These have the tongue cylindric, ensheatlied, and forked at tlu^ cud, and project it as a delicate tactile organ. 128 It, is slated by Professor Marsli that these reptiles possessed scales ; that, in Clidastes, a complex pattern was ])roduccd l)y alternate rows of scutes of different shape and size. They are osseous, but thin, and generally united by beveled edges. Such structures would produce a distinct effect in the living animal. I had already inferred the existence of dermal scales, and figured them in a restoration of Mosasaurus, published in the American Nat- uralist,^ but had not suspected osseous scuta. It is a little singular that I have never detected them among the numerous skeletons of these reptiles which I have exhumed in Kansas and elsewhere ; nor have any been sent me by Professor Mudge. The proportions varied somewhat in the known genera. Thus, in Clidastes, we see the greatest attenuation of form ; while, according to Marsh, the caudal series is less elongate in Liodon. In Clidastes and Platecarpus, the humerus is very short and wide, broader than the femur. In iodon, the humerus is more slender, and not very diiferent in proportions from tlic femur; hence, the flippers were more distinctly pedunculate. • Classification and distribution. The well-distinguished genera of the order known from North American strata are the following: I. Cervical hypapophyses separate, articulating: a. A zygosphenal articulation : Chevron-bones coossified with centra Clidastes. Chevron-bones free Sironecfes. aa. No zygosphenal articulation : Teeth subcylindric conic; humerus short, platelike; chevron-bones free Platecarpus. Teeth mostly compressed, cutting; humerus with nar- rowed extremities ; chevron-bones free Liodon. Teeth subcylindric faceted ; chevron-bones in part coossified . . Mosasaurus. II. Cervical hypapophyses continuous and (nitire : No zygosphene Baptosaurus. The material obtained in Kansas, during the autunm of 1871, by the writer, proved conclusively that this order of reptiles attained a predominant '18C0, \^. ai. 129 importance during the Niobrara epoch of the Cretaceous period. This is indicated by the great profusion of individual remains and specific forms. Although occurring in America, wherever the Cretaceous formation appears, they are, so far, more numerously represented in Kansas than elsewhere. Though not rare in New Jersey, crocodiles and tortoises outnumber them ; but, in Kansas, all other orders are subordinate to the Pythommorpha. As is now well known, since 1868,' the seas of the American continent were the home of this order; while they were comparatively rare in those of Europe. In the latter country, we have four species only determined by paleontologists, viz : Mosasaurus 2 Liodon 1 (?) Saurospondylus 1 In North America, the species have been exactly determined from three regions, as follows : Crreensand of New Jersey. Mosasaurus 6 Baptosaurus 2 Clidastes 2 Liodon 4 (?) Diplotomodon 1 15 Rotten limestone, Alabama. Mosasaurus 1 Holcodus 1 Liodon 3 Clidastes -• 2 7 Chalk of Kansas. Clidastes 10 Sironectes 1 Platecarpus - 11 Liodon 4 26 ' See Traiisactious of tUe Americau Philosophical Society, vol. XIV. 17 c 130 Wg have additional species from — North Carolina (Mosasaurus) ■ 1 Mississippi (Platecarpus) 1 Nebraska (Mosasaurus) 1 Making, with the others from — New Jersey 15 Alabama .• 7 Kansas 26 A total of '. 51 Of these, I am not acquainted with any species which extends its range into two of the areas above named ; while some of these districts possess peculiar genera. It is, nevertheless, premature to draw any conclusions as to geographical range, as most of the species are known as yet from but few specimens. HistorT/. The knowledge of the structure of the animals of this order has been due, almost exclusively, to the labors of three paleontologists, viz, Georges Cuvier, Prof 0. C. Marsh, and the writer. Cuvier determined the characters of the dentition, and of the anterior regions of the skull, and of the vertebral column. Professor Groldfuss added little to this beyond the description of the parieto-quadrate and postorbito-malar arches. The writer ascertained the structure of the posterior part of the skull, including the walls of the brain-case, the suspensorial apparatus, the pterygoid and palatine bones, and the median hinge of the lower jaw ; also, of the scapular arch and fore and liind limbs, except the phalanges. On this basis, the determination of the affinities of the order was made. Professor Marsh determined, for the first time, the presence of hind limbs, and described the pelvic arch ; he also determined the relations of the phalanges of the fore limb, the presence of two small supernumerary cranial bones, and the probable existence of dermal scuta. CLIDASTES, Cope. Vertebral column exceedingly elongate, the vertebrse united by the zygosphenal as well as the usual articulation ; the zygosphene elevated but i;n little above tlic plane of the zygapophyses. Chevron-bones coossified! cervical hyjjapophyscs free. Humerus short and very wide. Parietal fonta- nclle pierced in the parietal bone. Tiie sijecics of this genus are, so far as known, the most elongate iu the order. The quadrate bone, in the most typical species, exhibits a very prominent internal longitudinal ridge, indicating a great degree of rotation of that bone, and hence external flexure of the mandibular rami. There are specific differences in the form of the palatine bones in this genus, from the more transverse or expanded type of the C.propytlwn, to that of the C. j>la?iif/otis, where they are narrowed posteriorly in some degree, to the C. tortor, where tjiey are vertically placed in the posterior half. Clidastes is nearly allied to Platecarpus, with which Sironectes associates it as an inter- mediate genus. The numl)er of species already known is considerable, and the genus is divided into sections, for convenience of reference: A. Centra of dorsal vertebrae depressed: a. Frontal bones with median keel: Clidastes tortou, Cope. A slender species of some thirty feet iu length, w ith a narrow, pointed head of two and a half feet. Its teeth are compressed, and with a cutting- edge fore and alt, and were eighteen in number on the under jaw: the palate was armed with eleven teeth. The frontal hone is light, and witli thin margins; it is keeled above for the anterior three-fourths of its length. On its inferior face, the olfactory groove is closed by the apposition of its lateral bounding ridges. Posterior to this point, the latter diverge and disappear; and a median ridge, with an acute edge on each side, carries the deep median olfactory groove, but disap- pears with the lateral ridges. There is no grooved triangular area in front of the foramen parietale. The imrietal bone below- presents a V-shaped, rounded ridge; the limbs embracing the narrow and small parietal fontanelle in front. The bone, in general, is' broad and expanded laterally. Its antero- lateral ala is largely underlaid by the postfrontal, and presents a transverse ridge for its boundary. The superior surface of the bone presents a flat, longitudinal surtiice; the angles bordering the temporal fbssse being obtuse, well se|)arated, and low. Bases of slender parieto-squamosal arches project from it l)eliin(l. 132 The postfrontal is large and jirominent, and terminates in the usual posterior process, connecting with the squamosal. The prefrontal is a slender, flat, triangular bone. Its orbital portion projects at right angles to the orbital margin of the frontals, and is, in its direction, at right angles to the exterior margin. The latter is in the hori- zontal plane, and is transversely plicate. A strong process projects inwardly from the lower side, and is continued across the latter as a curved, flat-topped ridge, to which the maxillary bone is articulated. It soon reaches the outer margin of the prefrontal. The suspensorium is flat (perhaps on account of pressure). Tlie opis- thotic sends a flat process to the parietal. The squamosal is, as usual, a sickle-shaped bone, with a flat extremity for articulation with the opisthotic. Unlike what is observed in Platecarpus and Mosasmirns, it presents no concave articular face below for the articulation (by ginglymus) of the quadrate. The exoccipital extends to near the end of the suspensorium, and terminates in a flat extremity with truncate border. The proiitic, on the other hand, terminates near the middle of the length of the suspensorium by a transverse suture. The basis cranii I have not yet found among the debris of this skeleton. Quadrate bone with long internal angle, and rather thick anterior ala, with broad, rugose margin. A prominent, obtuse ridge is continued from the internal angle to the inferior articular extremity; the distal portion being more acute. A rugose process projects at the point where the posterior hook approaches the body, and is continued, as an elevated, narrow ridge, parallel to the one previously mentioned, to the distal articular surface. A button- like knob appears on the posterior margin of the hook opposite the meatal pit. A strong ridge extends, on the outer face of the bone, from opposite the end of the hook to the base of the great ala. The distal articular surface presents two planes : the narrower at the end of the posterior pair of ridges above described ; the larger considerably less distal, like a broad step. The maxillary bone descends regularly in front, uniting with the premax- illary by minute suture. Its posterior extremity is slender and acute. The premaxillary is short conic ; not particularly prominent. The palatine bone lias a slight expansion on the inner side ; on the outer, the margin is very narrow. Tlic teeth number seventeen on the maxillary bones. They are com- 133 pressed, least so anteriorly, and with a cutting-edge from base to crown as far as the fifth from the front ; in those anterior to that point, the posterior edge is discontinued. There are sixteen palatine teeth, which are smooth, and without anterior cutting-edge. The frontal hone has a low carina along the median line of its anterior portion. Vertebra of the cervical and anterior dorsal regions with round articular faces, not emarginate for the spinal cord. The bodies are elongate and somewhat contracted, and marked everywhere with finer and coarser striae. Hypapophyses prolonged on the cervicals ; the free one of the atlas with a j)rolonged keellike process. Meaiuremente. M. Length of tho axis witb tbo odontoid process 0.078 Diameter of the ball of a cervical, vertical 0. 02U Diameter of the ball of tho same, trausverso 0. 026 lixpause of the diapophj ses of tho same 0,084 Len};tb of the centrum of the same 0. O.Vi Length of the maxillary bono 0. 3G1J Length of the ramus mandibuli behind the dentary 0.310 Length of the promaxillary 0.040 Total length of the cranium (2.33 feot) 0.713 Length of tho pterygoid and palatine 0. 315 Length of the centrum of the posterior dorsal vertebra 0.066 Diameter of the ball, vertical 0. O.iy Diameter of the ball, transverse 0. 038 The bones of this species are all light and slender. The elongation of the vertebrae indicates that, if their number was of the usual amount, the animal was of more than usually slender proportions. The position in which it was found was a partial coil; the head occupying the inside of a turn of the dorsal vertebra?. As compared with E. dispar and E. ve.lox of Marsh, the present difi'ers in the lack of depression of the centra of the vertebrae, especially the anterior, and in some details of structure of the quadrate bones, as well as tiie larger number of teeth. Discovered in Fossil Spring Canon, in the gray limestone, by Martin Ilartwell and Sergeant William Gardner. But one specimen was found, which includes the greater part of the cranium, with the vertebra? as far as the lumbar region. Clidastes stenops. Cope. Indicated l)y a large part of the skeleton of one individual, and fragments of two others. The first includes a large part of the cranium, willi l)()11i quadrates, and fifty vertebra-, including the a.vis. The characters arc similar 134 to those of tlie preceding species; but all the bones are more massive, though of the same dimensions. The teeth are strongly compressed with cutting-edge fore and aft, and with the surfaces distinctly faceted; there are seventeen on the mandible. The palatine bones are stouter than in C. tortor, but the teeth are not larger, and are probably as numerous, as they are similarly spaced. The i)arietal is thicker than in C. tortor, and flat above. The decurved lateral portions are short antero-posteriorly ; behind these, there is a promi- nence on the inferior face, which is broken, but probably ends in the acute median termination of the bone. The apex of an inferior V-shaped ridge is ])reserved. The parts of the frontal preserved show the olfactory groove nearly closed, and its division in front into two contiguous lateral grooves. The middle of the upper surface is plane; its anterior part, with a low keel. The prefrontal is of peculiar form, and displays the greatest difference from that of C. tortor. Instead of being a horizontal bone, it is so oblique as to be nearly vertical. From this follows an alteration of the relation of all the parts. The squamosal suture with the frontal, which is marked by pecul- iar concentric rugosities in both species of this genus, instead of being on the upper, is nearly on the under surface, though oblique to both. The lateral margin is subinferior and plicate ; the crest of the inner side bounding the maxillary projects far below it in front. In consequence of the form of the bone, there is less expansion of the face in front of the orbits than in other species of the order; whence the face is much narrower, and the name stenop!< is appropriate. The portions of the prefrontal of the other side whicli are preserved are similar to those described. Tiie characters of the suspensorium are in the main as in C. tortor. The quadrates, hke those of the last species, have a very prominent internal angle. They present various differences, which may be regarded as only individual: for example, the edge of the great ala is not expanded inward, but only outward; the distal articular extremity is wider; the poste- riorly decurved hook is more contracted, forming a deeper internal concavity behind the internal angle. The button on the posterior aspect of the hook is wanting; its place being taken by a recurvature of the smooth articular face along the margin. Characters of more importance are, the lack of the two ridges which bound the posterior face of the distal end of the bone, that face being thus convex instead of concave ; and the process below 135 (lie meatus is isolated, and not continued into a ridge, except externally, where it gives rise to the heavy ridge which extends to the base of the great ala. Tlie vertebrte exhibit round articular surfaces ; those of the dorsal region being rather stouter than the cervical, though the difference does not appear to be so marked as in the preceding species. The anterior caudals possess wide diapophyses. The articular faces are a vertical oval, a little contracted above, sometimes by a straight outline. They preserve a peculiarly elongate form. Measurements. M. Length of the axis (aloiio) 0. OCO Diameter of the ball, vertical , 0. 0ii7 Diameter of the ball, horizontal 0.027 Length of a posterior dorsal 0. 000 Diameter of the ball, vertical 0. 03;{ Diameter of the ball, transverse 0.038 Length of the caudal with the flat diapophysis 0. 033 Depth of the cnp of tho caudal 0.031 Width of the cup of the caudal 0.030 Length of the mandible (28 inches) 0.720 Depth at the coronoid process 0. 150 Depth at the proximal end of the dentary 0.074 Depth at the distal end of tho dentary 0.030 A fine specimen of this species was found by Martin V. Hartwell near Fossil Spring; and portions of a second were found by Lieut. James H. Whitten, on a bluff on Butte Creek, during my expedition of 1871. aa. The frontal bone without median keel: Clidastes planifrons, Cope. A large species, represented by large portions of the cranium, including quadrate bone; by cervical and dorsal vertebras, and fragments of other ele- ments, all belonging to one individual. They are well preserved, and have suffered but little from distortion. The frontal hone is especially massive, and is plane on the supericM- surface. The superciliary borders are strongly concave, a feature either littU; or not at all marked in other species known to me. It is thickened ; but the (bssa for the postfrontal bone extends far toward the front and middle on the inferior surface. In front of the prefrontal angle, the frontal contracts, nar- rowing regularly to the line of the nares. The prefrontal has the remarkable form characteristic of Clidastes stenops ; that is, with the exposed face subver- tical or steeply roof-shaped, instead of horizontal. A groove descends on 136 each side to each nareal orifice, and the intervening longitudinal ridge is deeply fissured hy a parallel groove. The parietal fijntanellc is entirely in the parietal bone. The postfrontal is massive. The quadrate bone presents a very prominent internal angle, as in other Clidastes, and has the posterior hook much prolonged downward and inward, with a button and surrounding groove on the inner side of one, but none on the other. The stapedial pit is a narrow oval, as in Lwdon proriger. The median posterior ridge is prominent, and united with the distal internal longi- tudinal, extending to the narrow posterior angle of the distal articular face. The internal ridge is prominent, dividing the internal face of the bone into two planes, the posterior of which is but little concave along its upper poste- rior border {i. e., on the inner side of the hook) ; this region is very concave in some species of the genus. There is a strong transverse obtuse ridge, which extends along the outer side, turning backward into a rough process opposite the origin of the base of the ala. Between this and the distal articular face is a subtriangular rugose area. The palatine bone has its anterior and poste- rior extremities broken away, the fragtnent supporting six teeth. The bone is flat, much as in the species of Plalecarpus, the tooth-line passing from the inner margin behind to the outer before, the roots being more exposed on the external side ; the external process is stout. The crowns of the palatine teeth are curved, with lenticular section, one face being much more convex than the other ; the enamel is shallowly striate-grooved. The articular faces of the cervical vertebrce are all transversely oval, not much depressed ; those of the dorsals are also transverse, but less so than the cervicals. Five cervicals and nine dorsals are preserved. The hypapophyses, both fixed and free, are very large and stout. The odontoid is large and prom- inent, and deeper than long. The diapophyses are short, and send a narrowed extension forward to the rim of the cup on all the cervicals and three dorsals. The vertical portion of their surfaces diminishes anteriorly as the horizontal extends, till, on the axis, it is horizontally subtriangular in outhne. . The zygosphen is smaller on the anterior than the posterior vertebra; ; on the latter, the zygantrum possesses special facets for it. The cups, especially of the dorsals, are emarginate for the neural canal. A smooth band borders tli(; circumference of the ball in front. The surfitce, in general, is smooth, will) rugose lines and grooves extending to the articular face of the fixed hypa- [M)pliysis and ;i|)c.\ of flic iVcf, and on I lie upper rool-likr smlacc ol ilir [mjs- 137 tcrior zygapopliyscs. The inferior surfaces of the centra display a more or less prominent longitudinal median ridge. Measurements. M. Length of the frontal bono to tho narea 0. 150 Width of tho frontal bono i)08tcriorIy 0. 110 Width of the frontal bono at thu orbits 0. 104 Width of tho frontal bono at tho uares 0.040 Width of tho palatine at the third tooth in front of tho transverse process 0.037 Width of the palatine just behind tho transverse process 0.035 Depth of the mandible at tho cotylus 0.040 Depth of tho splenial condyle 0.032 Width of the proximal articular surface of the quadrate (transVerse) 0.023 Width of the distal articular surface »*^ fjiri"^ Length of the third cervical centrum 0. 0G2 Depth of the ball of tho third cervical centrum 0.030 Width of the ball of the third cervical centrum 0.037 Length of tho articular end of the fixed hypapophysis 0.025 Length of tho free hypapophysis 0.029 Length of a median dorsal centrum 0.072 Width of tho ball of a median dorsal centrum 0.048 Dei)th of the ball of a median dorsal centrum 0. 040 This species need only be compared with the Clidastes stenops, Cope, which exhibits the same peculiarity of roof-shaped prefrontal bones. That species has the cervical articular faces entirely round ; the frontal bone is keeled in the middle, and the palatine much more vertically comjiressed. The quadrate bone differs in various respects ; among others, in the round form of the stapedial pit. As compared with the species described by Pro- fessor Marsh as Edestosaurus dispar and E. velox, it differs in the form of the (piadrate, which, in these species, is much as in C. tortor and C stenops; i. e., with sliort proximal hook, oblique inferior articular surface, round pit, &c. In this species, the quadrate is truncate distally, &c. This fine s^jecies was discovered by the veteran geologist, Prof. B. F. Mudge, during his annual expedition of 1873. AA. Centra of anterior dorsals compressed. Clidastes cineeiarum. Cope. The largest species of tliis genus, as indicated by the zygosphen articu- lation of the vertebrae. The region whore it was foimd is (he same as the last, but the speci- mens were taken from I ho gray bed, perhaps thi^ santc that ]iran8e of the diapophyses of the anterior cervical 0. 09.") Expanse of the anterior L'ygapophyses - 0. 064 Expanse of the diapoi)hy8es of the anterior dorsal 0. 115 Length of the centrum of the anterior dorsal 0. 071 Length of the centrum of the anterior caudal 0. 053 Depth of the cup of the anterior caudal 0. 044 Width of the cup of the anterior caudal 0. 041 Width of the neural spiue 0. 03;i Elevation of the neural si)ino (apex lost) 0.070 Diameter of the centrum of the twenty-fourth caudal, vertical 0. 039 Diameter of the centrum of the twenty-fourth caudal, transverse 0.040 Length of the centrum of the twenty-fourth caudal 0. 042 This species appears to have had proportions not unlike those of Plate- carpus coryphceus ; the specimen described being larger than that on wliich the latter was based. It is also ratlicr larger tlian the Clidastes planifrons, Cope, llic largest of its genus, Init which, since its caudal vertebfie are unknown, may yd Ik; I'ouiid to he a Sironectes. It differs specifically fruiu the S. angullferus ill llic less (Icscliipinciit of I he zygi)s[>iicii, especially im I he aiilciior verlebtje, 141 and its deep emargination in front, where well developed. From its general characters, I anticipate that the quadrate bone of this species will prove to be more like that of the Platecarpi; that of G. planifrons is that of the genus to which I have referred it. PLATECARPUS, Cope. Vertebrae very numerous ; caudal series very elongate ; zygapophyses strong; zygosphen wanting, or very rudimental. Chevron-bones free. Teeth siihround in section, acute, and curved. Humerus short and wide. While the form of the humerus in this genus is that of Clidastes, the vertebral articulations are those of Liodon, the zygapophyses being, however, stronger. The teeth are different from either. Besides the characters assigned to this genus in the analytic table already given, Platccarpus is characterized by the position of the fronto- parietal fontanelle on, or very close to, the coronal suture, instead of in the broad plate of the parietal bone posterior to the suture, as in Clidastcs. The genus is also characterized by the form of its teeth, which are neither com- pressed, as in Liodon, nor broadly, angularly faceted, as in Mosasaurus (and Holcodus, fide Marsh), but are curved and subcircular in section. The exposure of the roots of the palatine teeth is largely less, or scarcely greater, on the outer than on the inner side. The form of the cranium is, in this genus, less elongate than in Clidastes, and the muzzle is often quite short and obtuse. The caudal vertebrae of the type-species P. tympaniticus are unknown; but its quadrate bone and the forms of its cervical vertebrse and palatine teeth are quite similar to those of the other species here referred to Platecaipus. Professor Marsh has referred the same species to a genus, Leslosaurus, Marsh, of which the species L. simus, Marsh, is regarded as type, and which he regards as nearly coextensive with the genus I previously de6ned under Dr. Gibbes's name Holcodus. He finds the coracoid of L. si?/ius to be deeply incised, as is often the case in Lacertilia. The name which I formerly used for this genus was originally applied by Dr. Gibbes,^ of Charleston, to a species represented by teeth from the Cretaceous of Alabama, but of which no other portions were known. Tiie teeth of the Kansas species referred to it are somewhat similar in character to tiiose described by Gibl)os; but it is evident that the latter belonged to an ' Oil Mosasam-us and aUies, in Smithsnniiin CtintriUutiona to Knowlculgp, IH.'il, 0 ; plntus. 142 animal more nearly allied tothc true Mosasauriis. The place of P/aiecarpus is evidently between Clidastes and Mosasaurus; the palatine bones being those of the former, and the vertebral articulations being identical with that charac- teristic of Mosasaurus. In all of the sjiecies, traces of the zygosphen appear; but in the H. coryphcRus, Cope, the rudiment amounts to a short process directed forward at the base of each anterior zygapophysis. The species known, as yet, are of medium size in the order. The species P. mudgei and P. tectulus resemble each other in the form of their quadrate bone, and are referred to this genus provisionally only. The P. simus, Marsh, resembles the P. crassartus, Cope, but differs in the depressed, instead of circular, articular faces of the dorsal vertebrae. It is probable that this genus had a considerable geographical distribu- tion. P. tympaniticiis has been found in A.labaraa ; and I suspect that other species from other localities belong to it. Platecarpus coryph/Eus, Cope. Characters. — Cervical and dorsal vertebrae with the articular surfaces depressed transverse, slightly excavated above for the neural canal. The dia- pophyses not continued inferiorly to the rim of the cup on the cervical ver- tebrse, and not receiving from it a cap of articular cartilage. Occipital crest much elevated. Quadrate bone small, the meatal pit depressed between bounding ridges above and below. Rudimental zygosphen not uniting into a keel above. Teeth slender, less curved than in P. ictericus. Description. — This species is chiefly based on one specimen, which includes the greater part of the cranium, and seventeen vertebrae, with ribs. Isolated portions of other individuals were also found in the same region of country. The disproportion between the diameters of the cervical and dorsal ver- tebrae is more marked here than in the species of Clidastes. The centra are also less elongate, though with larger diameter. The cranium is relatively much smaller ; the teeth absolutely smaller, though the quadrate bones are of equal size. The genei'al character of the species is stouter, but less strongly armed, and less elegantly built. The hypapophysis of the atlas has a short small keel below. The neu- ral spine of the axis is elongate, but less so than in the two Clidastes, trun- cate behind, with a median groove, into which the anterior kocl of the neurnl 143 spine of tlic lliiid fcrvical vertcljra is applied. Tlic diapopliysis of this ver- tebra has a short vertical articulating surface, and is continued into a longi- tudinal keel, which disai)pears before reaching the edge of the cup. The same process of the axis has a longitudinal parallelogranimic articular sur- face. The supraoccipital is very thick, and is roof-shaped, the keel rising nearly perpendicularly from the foramen magnum. The suspensoria are directed both upward and backward, at about an angle of 45° in each direc- tion, and support, on their extremities, the squamosal bones. These are pro- longed, each forming a part of its appropriate arch. Tlie occipital condyle is transversely oval. The sphenoid bone embraces, as usual, the basi-occipital protuberances ; it is not carinate on the median line below. It sends out, on each side near the anterior extremity, a subhorizontal, laminar process. The quadrate hone is much like that o{ P. ictericus, but is relatively smaller. While the teeth in that species are smaller, the quadrate is larger; hence, the difference in the species is, in this point, quite striking. The internal angle is prominent, but very obtuse, and is the summit of a very thick, obtuse ridge, which extends to near the distal articular face. Tbe posterior hook is much prolonged downward, and has no buttonlike process or extension of the articular surface on its posterior face. This face presents a strong rib along the meatus, ahd, disappearing above the pit, throws the latter into a depression. This is increased by the swelling of the internal angular rib. A prominent knob, very rugose at the extremity, rises beneatli the end of the hook, and bounds a concavity between it and the internal rib. The latter closes the concavity by curving round toward the knob above mentioned. A keel rises interior to the rib, and below it, and continues into the internal angle of the articular extremity. Another very prominent keel extends from the knob beneath the hook to the base of the great ala. The articular extremity is transverse, and in one plane. The maxillarij bone is marked with shallow longitudinal grooves. It supports eleven teeth, and has a rather steeply-descending premaxillary suture in front. The nareal expansion in front occurs opposite the fourtli tooth. The teeth are rather long, slender, and incurved and recurved. There is a distinct cutting-edge anteriorly, and on a greater or less part of the length of the posterior face. Tlio crowns are four or five faceted on the outer face: 144 the inner face is more numerously faceted, and striate-grooved. The section at the base is subcircular; higher, the outer face is iiatter, the inner more con- ,vex. The apex is acute, and the cutting-edges strong. The frontal is narrow, and differs from the other Platecarpi here de- scribed in having the olfactory groove closed by contraction behind. Both palatines are preserved. They support tw^elve cylindric conic teeth, which have recurved apices and striate enamel. The section of the bone is a flat, transverse oval, where the external transverse process is given off". The shaft of the bone is much expanded inwardly, with a thickened margin ; exteriorly, the margin is thin, and is nearly followed by the series of teeth whose bases are exposed externally, and are therefore pleurodont. The emargination for the pterygoid is very deep. Measurements. M. Length of the axis with the odontoid 0.074 Length of the third cervical 0. 048 Diameter of the ball of the third cervical, vertical 0. 031 Diameter of the ball of the third cervical, transverse 0.033 Elevation of the spine of the third cervical from the centrum 0.046 Length of the posterior dorsal 0. 068 Diameter of the centrum, vertical 0.033 Diameter of the centrum, transverse 0.048 Length of the basioccipital and basisphenoid 0. 084 Elevation of the occipital crest above the floor of the foramen magnum 0. 030 Length of the suapensorium from the foramen ovale 0. 090 Length of the os quadratum 0. 073 Width of the distal extremity 0.036 Length of the os maxillare 0.210 Depth of the os maxillare at the third tooth 0. 036 Length of the fourth tooth 0.032 Length of the crown of the fourth tooth 0. 021 Length of the pterygoid bone 0. 155 This fossil was foftnd by the writer projecting from the side of a bluff in a branch of the Fossil Spring Canon, near the mouth of Fox Cafion. The l^luff" was from eighty to one hundred feet in height; and the Platecarpus v/as taken from a position forty feet below the summit, from the yellow chalk. Platecarpus ictericus, Cope. Characters. — Internal angle of the os quadratum close by the meatus, and continued as a rounded ridge separating the anterior and posterior internal faces of the bone. Median posterior ridge not prominent. Centra of dorsal ver- tebras depressed. Humerus broad, short. Description. — This species is represented by portions of a cranium, as post- 145 frontal, suspe.usorial, pterygoid, articular, and qiiadialc Ikhics; hy parls or wholes of" several vertebni;, which are all dorsals; and Ijy soapida and cora- coid, with many elements of the fore linil). The latter include luimenis, radius, a carpal, and numerous metacarpals and plialansrcs. The species is tirst well characterized by the form oC tin; quadrate bone. The specimen lacks a portion of the ala, and the postero-superior decnrved pro- cess, but is otherwise perfect. Its form is intermediate between that in Liodon vaiidus, Cope, and Mosamurus depressu,s, Cope. Its internal any;le of the proximal extremity is posterior to its usual position, as in tlio former species, but is less ])r()niinent than in it. It extends to near the distal end, disappear- ing between tiie extremities of the median posterior and the distal longitu- dinal angles. Tiie former of these is short, and it disappears l)y a gradual descent distally in a very rugose margin. The distal longitudinal is short and acute, not prominent at the distal extremity. From the posterior posi- tion of the proximal internal angle, the alar articular surface is somewhat elongate. The postero-internal face above the meatus is pro[)ortionateIy short. The meatal pit is scarcely one-fitth the usual size, so far as determin- able from the present surface; but it is |)ossible that tin; greater part is filled by an impacted mass of bone derived from the adjacent ridife. The margins of the articular extremities and of the ala are striate and papillose ruyose. No meatal knob. The sus{)ensorium is slender. It is peculiar in the great extent of the exoccipital element, which covers the whole superior surfiice, and extends externally over the opisthotic to the squamosal, concealing the former, excejit its anterior margin. The prootic sends a small proximal portion only to the superior face. The pahitine has been free from its fellow medially, A distal and median portions have hecn lost ; the remaining fragments presents i)a.ses and alveolse for eleven teeth. Tiie fangs are rugulose and I)ut little swollen ; probably five to .seven .«tood on the lost portions. The i)ases of the crowns are circular. The external process of the bone is slender and flat. The portion of the mandible preserved includes much of the articular, and adiicreiit parts of the angular. The latter forms a narrow band on the lower edge of tlie external face, and one twice as wide on the inner face. The only characteristic feature is the lowness of the ridge which descends 19 c 14G aiul extends iiuteiiuily tVoiii tlie uiilcrioi- uiargin of the cot} Ins I'ur I he qua- drat um. Of the vertebrge, several are so distorted by pressure as to be uncharac- teristic. Two well-preserved anteiior dorsals have transversely oval articuhir surfaces excavated openly above I'or the neural canal. One is from a position anterior to the other; and these surfaces are less oval, (hough still transverse. The centra of both are very concave in |)rolile l)el()w, and expand botii infe- riorly and laterally to the edge of the cup A deep groove surrounds the base of the posterior face. In the anterior dorsal, the neural arcli is presiMved. It exhibits an approach to a zygosphen articulation, more marked than in any ■ otiier Pldtccarpus, and is hence nearer Sironecte.s in tiiis respect, as well as in the slender pterygoid. A zygosphen is not separated lioni llie zygapophyses, owing to their connection by a lamina of bone. The notches at the posterior end of the arch for tliis prominence are marked. The neural spine had a long anterior ala, the i)ase of which extends 1o tlie summit of the neural arch. It presents a fine slriation vertical to the centrum and oblique to the edge of the bone, as is seen iu C. propython, Cope. The diapopliysis on this ver- tebra looks obliquely upward, and carries a vertical articular surface, which is concave behind. The line of its lower extremity tiiUs the depth of the neural arch below the latter, and of its upper reaches the apex of the canal in front. The more posterior vertebra has, as usual, a broader articular rib-surface, the diapophysis being flattened above and below. The marginal and angular sur- faces are striate-rugose on these and the other vertebrsTe. One of the free hypapophyses of a cervical is preserved. It has a subtrigoual section, and is longer than wide, and obtuse. Its posterior faces are exceedingly rugose. A cervical rib is compressed and short. Head narrow, large, simple ; the adjacent sides striatc-rugosc. Sides with a shallow groove. The scapular arch is represented by an entire right scapula and proximal part of right coracoid. The former is broader than in any of the species in which I have seen it, and is Hat and thin above. Its anterior extension is greatest below; its posterior above, at the superior angle. The lower poste- rior margin is strongly concave and thickened. The antero-superior margin is a regularly convex arc of more than 180°. The lower portion in front is on a different plane, and is the rudimental acromion. Tlie articular surtiuc is rugose, and the glenoid cavity not less so. The proximal portion of the coracoid is flat. It presents the usurd fo; a- 147 men iieir tlic antt'rior iiiiugiii; and tin- shorter concavity of tlu; aiiti'rior margin leads to the belief that tin; aiit(!rior extremity of the bone is the more pro- longed, as in Clida^tes 2»'opytho7i. The glenoid cavity is not concave, but merely two adjacent llattened rHgose surfaces. Consequently, llic liuments has no head, i)ut merely an elongate articular surface, which e.\hil)its a median keel and a shoit angular expansion near the middle. This \nnw. is of remarkable form, more resembling that I have descril)ed in C pro2)ytfion^ than any other, and very diiTerent from that described in Lindoii diispelor. It is a broad Hat bone, expanded at the extremities, and in one iilaiir distally, so as to be as wide as long. In the present individual, it is crushed by pressure, so that its thickness is not readily deterininable. Its external surface rises into a crest medially at the narrowest portion, which continues to the lateral angle of the proximal end, following parallel to one of the l)orders. A moderate thickening exists on the opposite side, a little beyond the extremity of the crest. Strongly rugose striae extend to the edges of tlie articular faces. An oval rugose muscular insertion exists on the least prominent of the distal angles, and not on a process, as in C propythoii. A bone, whicli, from its analogy to the radius of the last-named species I supjiose to be that bone, accompanies the others. It is tlat, truncate prox- imally, and with nearly parallel borders on the proximal half. Distally, it is obli(|uely expanded ; the outline forming a segment of an ellipse, whose axis is oblique to that of the bone. Its extremities are rugose-striate. One carpal remains; it is a quinquelateral bone, one side being marginal and concave. Perhaps it is the intermedial. There are several elements, which arc pro!)ably metacarpals. Tiie general struclnrc of the wiiolc liml) may be determined from these and from the numerous ])i'ialangr.!<. Tiic i()rmcr are flattened and with oblique extremities; the latter more cyliiidric, with a transverse truncation. Both have a median contraction, which becomes less marked in the distal ones; these are also more cylindric, entirely so at the distal extremities, whicli are concave. All of these elements are rod-like, much more slender than any of those figured by Cuvier or Leidy. Tliose immediately following the metacarpals are flattened, i>ut thickened distally. The number of disds cannot he readilv determined, I)ut i()ur nuiy i)e ' Sec TrniiRactioiiB of thu American Philosopliical Society, 18fi9, p 219, Table XII, tig. 17. 148 certainly clistinguislieil. The genenil similarity in construction of the ninims to that of a cetacean mammal is noteworthy. Measurements. M. Length of the suspensorium anteriorly 0. 1 1 1 Width of the suspensorium, medially 0.031 Quadrate, greatest length 0. 09'J Quadrate, width of the ala 0. VCM Quadrate, thiclcness behind 0. o;!0 Quadrate, length of the distal extremity 0.043 Palatine, length of six alveoli 0. 0."-.& Anterior dorsal, length of the centrum 0. 050 Anterior dorsal, width of the eup 0. 0,')1,''> Anterior dorsal, dejith of the cup 0. 03rt Anterior dorsal, expanse of the posterior zygapophyses 0. 03yr> Anterior dorsal, expan.se of the diapophyses - 0. OUl Anterior dorsal, width of the neural canal 0.0135 Anterior dorsal, deptli of the neural oaual 0. Oil Posterior dorsal, depth of the ball 0.049 Posterior dorsal, width of the ball : 0. OJ-2.^) Posterior dorsal, length of the centrum 0. OS.':^ Posterior dorsal, expanse of tlic diapophyses 0. 088 Scapula, length 0. 14.''> Scapula, width, proximal 0. 070 Scapula, width, median 0. 112 Coracoid, width, proximal 0. (KiCi Humerus, length 0. l.'>4 Hnmerus, width, proximal 0. Hi) Humerus, width, median 0. (I7.> Humerus, width, distal (restored from C. propijlhon) 0. 15M Radius, length 0. 111". Radius, width, proximal 0. 001 Radius, width, distal (oblique) 0. 105 Carpal, length 0. 040 Carpal, width 0.037 Metacarpal, length 0.005 Metacarpal, width proximally 0.045 Metacarpal, width medially 0.018 Metacarpal, widih distally 0. 034 Phalange (medial), length 0.085 Phalange (medial), width proximally 0. 027 Phalange (distal), length 0.059 Ph.alange (distal), width dist.illy 0.0082 Ramus niandiljuli, dei>th in front of the cotylus 0.056 Cervical rib, lengtli 0.074 The total lenylli of the anterior limb could not have been less than 0'".fl(), which allows of live phalanges in tiie longest digit. There may have been more. That tlie digits were of unequal lengtli is indicated liy portions ot two in matri.\ accompanying (he specimens, where th(^ articulation of two phalanges falls opposite the shaft of one of the adjoining digits. The pha- langes were separaled liy a short interval oi cartilage. 149 The size of this roittili' was near that of Liodon validus. pfiliaps tliirtv- - five to forty feet in length. The specimens on vvliich this species rests were discovered hy l^rof. B. F. Mndgc, formerly State geologist of Kansas, now professor of geology in tlie State Agricultural College of Kansas, on the north bank of the Smoky Hill River, thirty miles east of Foi-t Wallace, Kansas. Numerous fragments of auollu^r larger individual were found by Professor Miulge near the same locality, which belong probably to tlie same species. Among them is a portion of the maxillary Ijone, will) ])ases of two teeth; the bases of the crowns wiiere broken olV are not com|)ressed, but slightly oval. A radius is a ilal lione. moic dilated al one extremity than that of Clidaskn pro])yt}ioii. Measvrtmentx. M. Lci)j;lh iil'tbo nuliiis ^- '0"^ Wiatli of tbr nuliiis at t-lu; niiriow extremity ''•"'"'* Width of till? riiiliiis ;it the wiilei' iixtieiuity O.OdO Wiiltbof thr iiulius nicilially ''•''■'- In addition to the two individuals proeure.l by Prof. B. F. Mudge, the writer obtained a considerable part of a third from a low blufTon Fox Caflon, soutli of Fort A¥allacc. This iiududes seventeen lumbar, dorsal, and cervical vertebrae, including a.\is, with rii)s, and a large part of the cranium, with both quadrates, occipital and periotic regions, etc. Its characters may be briefly pointed out as follows : Articular surfaces of dorsal and cervical vertebrte transverse oval, exca- vated above lor neural canal ; diapophyses not extending below to the edge of the cup, hence not receiving an area of articular cartilage continuous with the rim. Occipital crest low, oi)lique; quadrate bone larger; the meatus depressed between ridges. A l)iitton of articular surface on posterior face of hook. Scarcely any rudiment of zygosphen. Teeth small, ranch incurved, faceted, and striale-ridged. Some characters, additional to those already derived from the first-known examples, may be added. The mandible supports only twelve teeth. The palatine bone is shorter anterior to the external process, and longer behind it ihan'niH.coryphceus. In our specimen, the posterior extremity is broken off, yet shows no indication of the (nnargination for the pterygoid bone an inch behind the position of its anierior extremity in H. con/p/ueiis. There are ten teeth on the part preserved, four in front of transverse process (six in H. cori/phfEii.-i), and six (proij-^bly seven) Ix'hind (fix in H. cori/ph(eus). 150 The plate is more expanded than in tlie last-named species, especially tlie thickened inner margin, which only approaches the basis of the last tooth (reaches the tooth-line at the (ifth in H. coryphceus). The ocdintal crest is low, and directed obliquely forward from the foramen magnum. The suspensoria are stout, and directed at an angle.of 45° in lioth the superior and posterior directions. Tlie basisphenoid is strongly keeled below. The qiiadratum is like that of H. coryphoius in its massive external angle and ridge, but differs in the shorter hook and the non-interruption of the groove between the internal angular ridge and the knob below the meatus. The cervical and dorsal vertehrcE displa}' the same disproportion in size observed in H. ionjpliceus. Measurements. M. Length of the os quadrat um 0. C81 Width of tho articular extremity of the os qnadriitum 0. 038 Length of the dentary boue 0. s;80 Length of the tooth of the dentary bone, third from behind 0.022 Length of the tooth, crown only 0.016 Length of the siispensorium from the foramen ovale 0. 108 Total length of the cranium (23 inches) 0. ;3go This species cannot be confounded with the Liodou pruriger, Cope, and L. congrops, Cope, owing to its depressed vertebral centra; from L. milchillii, DeKay, the equal and numerous pterygoid teeth separate it at once. PLA.TECARPUS CUKTIROSTRIS, Cope. The specimen below described was found by the writer on the denuded foot of a blufi" on the lower part of Fossil Spring Canon. The posterior part of the cranium, with several vertebrge, was found exposed, and many other bones, including the cranial, were found only covered by the superficial washed material. Other portions were exposed on excavating the blue-gray bed of the side of the spur adjoining. The name has reference to the abl)re- viation of the head and jaws. These are relatively shorter than in any other species here described where these parts are known. The end of the muzzle does not overhang, but descends gradually to the tooth-hne. There are but ten maxillary teeth and two premaxillaries on each side. Size about that of P. coryplicnus. Characters. — Cervical and dorsal vertebrae with transversely oval articular faces, which are little depressed, and, though not continued to the base of the neural arch, are scarcely excavated above for the neural canal. The diapophy- 151 sis with stout iiitVriur horizoiitul IjraMcli, which is capped h_v an cxlcnsion of the articular cartilage from the rim of the cup. Occipital crest elevated, sub- vertical. Quadrate broad below ; pit sunk between Ijounding ridges. Description. — There is a great disproportion in the sizes of the cervical and posterior dorsal vertebrae ; the centra of the latter are rather more de- l)ressed than those of the former. They are similar in proportions to those of the other Platecarpi, and shorter than those of the Clidastes. The short axes of the articular faces are sub vertical. The rudiment of zygosphen is seen in the sliglit anterior prolongation of the roof of the neural canal. The keel of the hypapophysis of the atlas is short and obtuse. The greater part of the cranium is preserved. The supraoccipital keel is vertical, and furnished at the summit with a plicate knol) for the insertion of a Hgamentum nuchce. The thickness of the walls of the bone is not equal to tliat in H. co7-yphcBus, and the suture for the parietal is a double squamosal; i. e., with a groove along the middle of the edge. The basisphenoid is but slightly keeled below, and is distally expanded into a horizontal plate on each side. The parietals are, as usual, conHuent, and send off two light arches postero- laterally tor union with the squamosal bone. Between their origins are two subparallel ridges, which disappear, the transverse section of the narrow part of the parietals being rounded. The lateral ridges within the temporal fossae are obsolete, while the convergent angles which bound the parietal table pos- teriorly are strongly marked. This table is nearly plane, and the foramen parietale is large. The frontal is narrowed in front, and has an elevated keel along its anterior half The ollactory groove is not much contracted behind, but is closed by the apex of the rugose area in front of the foramen parietale. The palatine bone is narrow, and the external margin is very slight, the bases of the teeth being exposed in that direction. The inner margin is much thickened downward, but not so as to be a vertical plate. The hinder part of the bone is flat and horizontal, with a long maxillary process. The pterygoid notch falls opposite the second tooth from behind. The whole number of teeth is eleven. The J aics are represented hy the greater part of all of the tootli-beariug portions. The maxillary bone is shallowly sulcate on the exterior face. Its proportions arc quite similar to those of the H. coryphcBus, but the teeth it supports are larger and fewer. There are none missing from the extremities of the specimen, the wliole number being ten ; in the H. corijphmtif, there are 152 eleven. The crowns iirt- incurved, t'acctcd externally, aiul striate ymoverl internally; there are cutting-edges in front and rear, both strongest near the apex ; the anterior continued to the base.the posterior wanting on the basal third on the median maxillaries. The anterior nareal excavation marks the fourth tooth from the premaxillary suture. The premnxillary hone is remarkable for its shortness and flatness at the extremity ; tins part being depressed and scarcely projecting at the lower margin in front of the anterior teeth. These, as nsual, number four. Both quadrate hones are preserved nearly entire. They have the same general character as those of PL ictericus and Fl. coryphcBus ; reseml)ling rather the ktter in the great length of the posterior hook, which is without posterior marginal button. The proximal internal angle is large and obtuse, and is continued into a prominent thick ridge. The latter divides below, the thick extremity turning outward and ceasing ; an acute ridge continuing inward, and joining the interior acute extremity of the distal articular surface. The sub- nieatal knob is broad and thick, and not prominent; and its extremity turns at an acute angle forward on the outer face, and forms the commencement of the great ala. The articular surface is straight crescentic, with an expan- sion on a tuberosity on the inner face (concave of crescent). The meatal pit is sunk between the ridges surrounding, one of which is on the outer margin of the posterior hook. The mandihle is nearly perfect. The dentary bone bears thirteen teeth, and, at the extremity, is contracted in both directions, and not prolonged beyond the base of the last tooth. The ridge, which descends from the cotylus along the inner face of the articular bone, is not nearly so strong as in the P. mudgei. Measurements. M. Length of tbe axis with tbc odontoid 0.06'i Elevation of the neural spine of the odontoid at the middle 0. 04(i Lenj^th of the third cervical (body) 0. OoO Diameter of the ball, vertical 0. 0i5 Diameter of tbe ball, horizontal 0. UlJ'i Length of a posterior dorsal 0. Oii.'i Diameter of the ball, vertical 0. Uod Diameter of the ball, horizontal 0. (•.')() Length of tbe basis cranii 0. U'JO Length of the suspensorium 0. 105 Elevation cf the occipital crest above the floor of the foramen magnum 0. (i 15 Length of the tooth-lino of the palatine 0. 115 Length of the maxillary bone U. LIU Length of the preniaxilUiry laterally O.0;l5 153 M. Widtb of tho piemaxillary at tho seuond tooth I). 041 Lcugtli of tho deutary 0. 2'ir> Lengtli of a luasillary tootb 0. OCO Length of tho maxilldiy tooth, crown only 0.023 Length of the os quadratum 0. 077 Width of the OS quadratum distally 0. 045 Length of the parietal 0. 085 Length of the frontal to the nares (median) 0. 110 Width of thefroutal hetweeu the orhits 0.077 Total length of the eranium (18.7r> iuches) U. 473 Platecarpus crassaktus. Cope. This saiiriiui, which is of larger size than the last, is represented by a series of dorsal, lumbar, and caudal vertebrEe, with some bones of the liinl)s The vertebrae are as much distinguished for liieir shortness as those of P. lolisplnis are tin- their elongation. Tiie articular faces are but little broader than dcej), and their planes are slightly oblique. They are very slightly truncate aljove by tiie neural canal. The interior face is somewhat concave in the longitudinal direction. The zygapophyses are stout, and there are no distinct rudiments of zygosphen. The dorsal vertebrae best preserved are those in which the diapophyses reach the middle of the sides of the centra, and have no horizontal limb. The latter are luirrow, and have not extensive articular extrcmi'al siirliices. The lumbars and anterior caudals have round articular surfaces. One of the latter, with strong diapophyses, but posterior, is subpentagonal in outline of cup. This species furnished the materials for the first description of the posterior extremities in this order of reptiles. The humerus is a remarkable bone, having the outline of that of Clidastes irropython^ Cope, but is very much stouter, the antero-posterior dimensions of the proximal extremity being greatly enlarged. The long diameters of the two ('xtiemities are, in fact, nearly at right angles, instead of in (he same plane; and the outline of tlie proximal is subtriangular, one of the angles being prolonged into a strong deltoid crest on the outer face of the bone, which extends half its lengtii. The inner or posterior distal angle is nuicli produced ; while the distal extremity is a flat, slightly-curved, diamond-shaped surface. The fibula is as broad as long and three-quarters of a disk. The phalanges are stout, thick, and depressed, thus differing much from those of Platecarpus ictericus. A bone which I cannot assign tit any other position than that of femur has 20 c 154 a peculiar form. It is a stout bone, but more slender tban the humerus. The shaft is contracted and subtrilateral in section. The extremities ore flattened, expanded in directions transverse to each other; the proximal having, however, a lesser expansion in the plane of tlie distal end. The former has, therefore, the form of an equilateral spherical triangle ; the apex inclosing a lateral fossa, and representing probably the great trochanter The distal extremity is a transverse and convex oval. This bone is either ulna, femur, or tibia, judging by form alone. Its greater length, as compared with the fibula, forbids its reference to the last; the trochanter-like process of the head is exceedingly unlike any examples of the second bone I have seen. Its reference to femur is confirmed by its presence with the caudal vertebrae of a similar species from near the Missouri River, Nebraska, and its resem- blance to the femur o^ Liodon dyspelor. Measurements. ii. Length of the humcius P- 10" Proximal diameter of tlio humerus 0. 005 Distal diameter of the humerus 0. 102 Length of the femur '2 The form of the humerus is something like that ui' Jchthi/osauius. Both this element and the femur are remarkable for their small size. They are scarcely half the dimensions of the elements of the anterior liml) of Plale- carpus ictericus; and are even less than those of L. dijspelor in proportion to the animal^ size Some of the ribs preserved exhibit cylindric shafts. The form of humerus nearly resembles that of P. sinms as figured by Professor Marsh, and it is probable that these species are very nearly allied. The vertebrfE indicate the largest of species of this genus. The remains above described were obtained by Prof B. F. Mudge, near Eagle Tail, in Colorado, a few miles west of the line separating that Terri- tory from the State of Kansas. 155 A series of twenty-nine caudal vertebrae, with and without diapopliyses, from a bliiti' on Butte Creek, belongs perhaps to this species. Tiic proximal specimens, at least, cannot he distinguished from those of Professor Mudge's collection. Tiie distal ones cannot readily be distinguished from tiiose of L. proriger. Platecakpus latispinis, Cope. The remains representing this species consist of seven cervical and dorsal vertebra^; live of them being continuous and inclosed in a clay concre- tion. It is a large species, nearly equaling the L. mitchiUii in its dimensions, that is, forty or Hfty feet in length, and is intermediate between such gigantic forms as hiodon dijqjelor and the lesser Platecarpi. The type-specimens were found by Prof B. F. Mudge, one mile southwest of Sheridan, near the "Gypsum Buttes." These display the elongate character seen in Liodon hevi.t, &c. ; l)ut the articular surfaces are transversely oval, thus resembling tlie P. iderkus. They are less depressed than in L. peiiatus and L. dyspelor. The cup and ball of the penultimate cervical are a little more transverse tiian those of the fourth dorsal, and none of them are excavated above by the neural canal. The last cervical is strongly keeled on tlie middle line below, and with a short, obtuse hypapophysis marking the beginning of the posterior third of tlie length ; the median line of the first dorsal has an obtuse ridge. There is uo keel on the fourth dorsal, but the lower surtace is concave in the antero- posterior direction. The diapophyses on the last two cervical and first three dorsal vertebrae have great vertical extent; the articular surface lor the rib is not bent at right angles on the first dorsal. Neural arches and spines are well preserved in most of tlie specimens. There is no trace of zygantrum. The neural spines are flat, and have considerable antero-posterior extent on cervical as well as dorsal vertebrae, and are truncate above. The first dorsal bears a long, strong ril). Mcasurement>i. ji. TrauBvcise diameter ol the cuji of the penultimate cervical vertebra 0. 0.")! Vertical diameter of tLe cup of the pemiltinuite cervical vertebra 0. (Ml Leugth of the centrum of the fourth dorsal, without ball (i. UT'J Vertical diameter of the ball 0. 0-l>=)5 Transverse diameter of tlie ball 0. 0D.")5 Elevation of the front margin of tin' neural spino of the penultimate cervical 0. OSJJ Anteroposterior diameter of tin; neural spine of the penultimate cervical 0.050 There are smooth bands around the balls, and the surfaces of the centra are striate to these. 166 The clej)ressed cups of the cervicals and auioriur dorsals distinguish this species from the Liodon validu.s, L. pror/g(u-, and P. viudgei. The same ele- ments are much larger and more elongate than in P. iclerkiis. It differs especially from these species of Platecarpus in the elongate form of the ante- rior dorsals. In four of the latter, at least, tlie inferior limb of the dia- pophysis is turned forward to meet the rim of tlie cup ; while this feature ceases with the last cervical in L. latispinis. The articular surfaces have planes at right angles to the axis of the centrum, and are not prolonged above, as in P. glandiferus. The last hypapophysis is very short, with the anterior margin transverse and elevated, as in the last-named species. Platecarpus glandiferus, Cone. A smaller species than the last, with apparently a greater llcxiljilily ot body, as indicated by the forms of the vertel)ral centra. It is represented l)y por- tions of two individuals frpni localities twenty-tive miles apart. There is, unibrtunately, in each case, only a cervical vertebra; but they agree in pos- sessing such peculiarities as distinguish them widely from anything yet known to the writer. One is an anterior, the other a posterior cervical. The articular sur- faces are transversely elliptic, and completely rounded above; that is, n('itlier truncated nor excavated for the neural canal. Their shoiter axes are oblique, i. e., make less than a right angle with the long axis of the centrum; and th<; articular surface of the ball is thus carried forward on tlie upper face to much nearer the base of the neurapophyses tiian usual, iu the anterior vertebra nearly touching them. The ball is, likewise, more convex than in any other species, having a slight central prominence in the posterior vertebra. There is no annular groove round the ball. In both, the articular surface of the hypapophysis is truncate and Ijounded by an elevation in front, a peculiarity not observed in any of the species already described There is uo trace of zygosphen in either. In the anterior vertebra, the diapophyses are nearly liorizontal; the posterior portion slightly thickened and oblique." The ante- rior ])oi-tion is thinned out, and very rugose above and below, and does not continue its margin into the rim of the cup. In the second vertebra, the dia- pophyses are very large, vertical, and with a horizontal portion rising in a curve to join the middle of the lateral margin of the cup. Neural spine nar- rowed upward, and keeled behind. 157 McanKrcments. u. Length of tlio (■fiitnim The first vertel)ra was louud by (he wriler at tlic loot ol' a bliill' on tlio lower part of Butte Creek; the second was procnicd bv Prot". B. F. Mndire, from a poinl one mile sonihi'ast of Slicridan, iicai" the North Fork of 1hi- Smoky Kivcr. It is this species that T compared with the Mosasaurus deprcssiis, Cope, in a report on (Jie collection made by Profpssf)r Miidge (Proceedings of (he American Philosophictd Society, 1871. p. 1G8). The size is similar, but tin; form of the articular surfaces of the vertebrae is very diflferent. Platecarpus mudgei, Cope. The characters dislinguishiug this saurian are the following: Vertebrae without rudiinenlal zygospheii; ([uadrate bones with plane surfaces from the proximal articular surface and the external obtuse-angled ridge to the meatal pit; tiie latter, therefore, not sunk in a depression as in the other species. 'Vhe determination of I his species rests on a series of specimens from the yellow chalk at a point six miles south of Sheridan. Kaiis. They consist of three vertebrie and traguieuts of atlas, with numerous por(i(jns of cranium and proximal extremity of scapula. The iiarts of cra/^wm preserved are the frontal bone without the anterior extremity, and with the adjacent parietal almost complete; j)arts of the basi- sphenoid ; the suspensorium ; the ossa tpiadrata; and the greater part of tlie surangular. The frontal is flat, witii thin edge, longitudinally hollowed on eatdi side of the median line, wiiicli is marked by a low but acute keel. There is an abundance of foramina and delicate grooves on the surface, and. posteriorly elevated striae, which converge to the median keel. Thi; median square ex- tension of the i)order of the parietal :s in tidvance of the lateral portion ol'tiie same, and not behind it as in Clidastes i»opython. The t()ntunclle is large. A marked feature is that the parietal crests unite into a low median ridge a short distance behind tlu^ f()iitan(^lle, and are not. as in ('. jiropi/thon, separated by a horizontal plane. The sntnn^s of the l)ones fonninir the side oi" the brain- 158 case are very obscure. Nevertlieless, it .ippt-ars that, the descending margin of the parietal does not descend to the front of the alisphenoid, but is mar- gined interiorly by the latter to the postorbital expansion. No part of the inferior margin of the alisphenoid can have reached the sphenoid, as it ter- minates in a thin edge, except for a short distance medially, where it is broken off. The inferior aspect of tiie parietal and frontal l)ones presents a furcate keel corresponding to the divergent parietal crests, and a very large funnel for the epiphysis of the l)rain. The olfactory groove- is deep and regular, and open like that of P. ir/eria/s. The si/rangv/ar hone is characterized by the pioniinent longitudinal crest, which descends on the inner side, from the front of the glenoid cavity to below the posterior attachment of tiie coronoid bone, where it terminates in a thin edge; also, by the short distance between the margin of tlie glenoid cavity (cotylus) to commencement (or end) of coronoid suture, indicating a shortening of the posterior part, at least, of the cranium. The bone is con- tinued forward only immediately under the coronoid (ciV. F. ictericux). The proximal extremity of the quadrate is characteristic, and exhibits features intermediate between those o( Fkitecarpi/s icterkiis, Cope, and the typ- ical species of Mosa-saurus, as M. fulciaius, M. dekayi, etc. The proximal artic- ular face is much like that of i)/. depressus (Transactions of the American Phi- losophical Society, 1S6J, p. 181, Fig. 48, No. 3). The internal angle is much smaller than in the Liodons, and more anterior; nevertheless, it is continued distally as a ridgelike angle, separating the antero-lateral from the postero- lateral faces as in them, and not presenting the gradual blending of the two sur- faces characteristic of the genus Mosasaurus. The postero-lateral face is thus flat proximally ; and the meatal pit, which is well developed, cannot be seen irom the antero-lateral tace. The distal part of the quadrate is lost, so thai I cannot determine the character of the ridges there. The basal element of the axis bears a strong hypapophysis without artic- ular faces, but very rugose surfaces The same portion of the atlas is a con- vex parallelopipedon, with median rugose tuberosity and very rugose exlrem- ities. Its surflice is not separated from its liody anterioily by a deep groove, as in P. ictcricus. The iirtirul.nr f\iccts of the srapu/a arc much lircKKlcr than in the other 159 species here described, indicating a iK-ad oi- widci- ;iiliciilatii)ii of liiuncnis. No limb-hones are preserved. The vertebra) are too miicli injnrud to be characteristic. One posterior dorsal now has a compressed centrum, or, at least, not depressed. The infe- rior face is convex transversely, and tliere is a slight concavity below each diapophysis; but it is clear that il has been so modiOed by pressure as to render its normal «hape a matter of uncertainty. Measiircmenfu. li. Piuictal, h'Uiitb 0.074 Pariftiil, widtli bet wren tlic anlci ior iiids nf tlio crests 0.048 Parietal, least widtli 0.022 Frontal, intcrorbital width 0. Od:i Qn.-idrate, width above 0.020 Quadrate, leiij;th from the pit to the proximal end 0. 023 Sui angular, length of the lower e anterior acute edge of t.iie neural spine. Thus, the form is quite different from that seen in the previously-described species, and constitutes a lower jrrade of rudiment. The fact that this zvgo- IGO sphenal roof is separated on cacli side from the zygapophyses l)y an acnfe groove gives the former a distinctness more apparent than real. The fixed hypapophyses are short and broad. The centra are not elon- gate. Those of the anterior dorsals present an obtuse keel below. Alcnsitremcnts. ST. Length of a median cervical 0. 04- Diameter of the ball of a median cervical, vertical 0. 0;.i9 Piameter of the ball of a median cervical, transverse 0. 0?3 Length of the anterior dorsal 0.\l4vJ Width of thecnp 0.0:W P'onnd by the author on a low bluff", or "break," on Bulte Creek, four- teen miles south of Fort Wallace.' A second specimen of this saurian has since been discovered by Profes- sor Mudge. The frontal hone is thick, and |)reseuts a median keel. The quadrate is flat on the j)osterior inner face, so that the stapedial pit is exca- vated in a plane surface; the internal proximal angle is nearly right. The vertebrse are small, and the hypapophyses short, and with htn-izontally trun- cate articular faces, as in the lype-speciineu. This species is the smallest known P///fecar/»/s. LIODOX, Owen. Vertebnx^ without zygosphcnal articulation, and with very weak zyga- pophyses; the chevron-bones not coossified to the centra. Teeth with opposite acute edges, compressed, lenticular in section. Humerus small, narrow. The quadrate bone in the known species of this genus is of small pro- portions, and presents a very prominent internal proximal angle and longitud- inal ridge. The structure of the cranial Ijoucs is Hght. The zygapophyses are weaker, and disappear more anteriorly than in any other genus, approach- ing nearest to Mosamurus in this respect. There are four species of the genus known from the Kansas chalk, all of which have the end of the premaxillary bone protuberant and truncate. A species of similar character has been described by Mr. Hector, from the Cre- taceous of New Zealand. Three species from the greensand of New Jersey arc similar in many respects; but the forms of their muzzles are unknown. The typical species of this genus {Liodon aiiceps^ Owen) is scx-^^ little known, but few remains liavinii so far been ohftiincd liom the English (dialk, 101 its locality and horizon. Nuinc rons Norlli American spocies rescmhle it, in the I'ornis of tlio crowns of the teeth, and it is probable, though not certain, that they agree in other respects also. Several names have been proposed for our species, the earliest of which is Macrosaurus, Owen. This name applies to species with compressed dorsal vertebra?, as L. Icevis and L. mi.tch- illii, both from the New Jersey greensand. For the species with depressed dorsal vertebrae, as L. validus from New Jersey, L. perlatus from Alabama, and L. proriger from Kansas, the name Nectoportheus was proposed, and briefly characterized (Extinct Batrachiaii Reptilia of North America, 1870, p. 208). Professor ]\larsh subsequently gave the Kansas species the name of Rhlnosaurus, which name being preoccupied more than once, I changed it to Rhampliosaurus} This name will remain for species of the type of L. proriger, if they be found to represent a genus distinct from Nectoportheiis or Liodon, of which there is as yet no evidence. LlODON PROKIGER, Cope. Tiie original description of this large Mosasauroid was based on material in the Museum of Comparative Zoology, Cambridge, Mass., brought by Prof Louis Agassiz from the Cretaceous beds in the neighborhood of Monument, Kans., and near the line of the Kansas Pacific Railroad. It consists of the greater part of the muzzle from the orbits, with the right dentary and left pterygoid bones nearly complete; one cervical vertebra (with hypapophysis); one dorsal; one caudal with diapophysis; and ten caudals without diapophysis. The characters presented by the vertebral column indicate an exceedingly elongate reptile ; the transverse diameter of one of the distal caudal vertebrae is less than one-fifth that of a jvoximal with short diapophysis ; while four consecutive ones of the former show but little variation in dimensions. This diminution amounts to two-sevenths of a transverse diameter of the larger form. With this ratio as a basis, fifty-three two-thirds vertebra? would form a complete series from caudals one-half the diameter of the last of the four to the proximal caudal above mentioned. There have been, no doubt, several caudals in advance of the latter, as the diapophyses are small. From the slow rate of diminution of the columns of other species examined, it may be ' This name was applied by Fitzinger to two spucies of lizards which had already received generic nonies, and hence becatiio at once a synonym. Fnrtlicr he did not characterize it. For these reasons, tlio name was not prcoccnpied at the time I employed it as aliove ; hence there is no necessity for Professor Marsh's subscqiieut name Tylusanrus, given on the snpposition of preoccupation. 21 c 1G2 supposed that sixty caudal vertcbraj is below rather than above the true iiumbei'. The cervical and dorsal vertebrae have been slightly crushed, as they laid on the side, and present a narrower diameter than is normal ; the cup of the cervical has not been distorted, and is deeper than wide, presenting the character of Macrosaurns. The rudimental zygosphen consists of a continu- ation of the roof of the neural canal in front, to adapt itself to the inner face of the down-looking zygapophysis of the preceding vertebra. The latter is thus received into a groove on the inner side of the up-looking posterior zyga- pophysis. The dorsals and cai'idals exhibit, with the cervicals, that minute, sharply-defined rugosity which characterizes all the projecting margins, especially those of the hypapophyses and diapophyses, in this genus and Clidastes. The whole surface of the cervical is marked with either inoscu- lating striae or impressed punctae. The same character marks the cranial bones, though they do not present such rugosity as the vertebrae. The proximal caudal presents a subhexagonal section, of which the infe- rior and supero-lateral sides are longest; articular faces about as broad as high. A broad, smooth space between the chevron-bones. Diapophyses with broad, ovate transverse section. A caudal without diapophyses, anterior to the middle of the series, esti- mated by the size, is but slightly deeper than long, and with parallel lateral outlines of the articular faces. The neural aixh is very much narrowed antero- posteriorly, but has a greater transverse extent at its lowest part ; above, the spine is much compressed, but not widened. The zygapophyses remain as rudiments just above the small neural canal, but do not probably touch each other. There are two anterior and two posterior narrow ribs on the upper portion of the neural spine. The more distal caudals have wider neural spines, and the arch has also a greater antero-posterior extent. The zyga- jjophyses are scarcely traceable, and the neural spine is strongly striate. The reverse arrangement is observed in Clidastes propython, where the neural spine of the proximal caudal has considerable extent, while those of the pos- terior and distal vertebrae are almost cylindric, especially the neurapophyses. Dimensions. Inches, Dorpal, length 3.25 Dorsal, width of the cup '. ...'. ii..''iO Dorsal, depth of the cup 2. 77 Proximal caudal, leugth 2. 14 1G3 Inches. Proximal, wiiltli of the cup ]' ' Proximal, tli of the cup ' • '■ Caiulal wit bout tlio diapopliyses, No. 1, leiisHi '• ' CaiKlal witliout tlie diapophyses, No. 1, deptli of tliocup '-J- *j-J Caiulal without tho diapophyses, No. 1, width of the cup 2.6 Caudal without tlie diapophyses, No. 1, height of the neural canal 0.4 Caudal without tho diapophyses, No. 1, antero-posterior width of tho neural spine 0.8 Caudal without the diapophyses. No. 2, length 1-2 Caudal without the diapophyses, No. 2, depth of the cup 2.15 Caudal without the diapophyses, No. 2, width of tho cup 1-S<5 Caudal without tho diapophyses. No. 2, width of the neural spine (antero-posterior) 1.07 Caudal without the diapophyses, distal, leugth 0.5^ Caui'.al without the diapophyses, distal, depth of the cup. 0.8.5 Caudal without tho diapophyses, distal, width of tho cup 0.64 Caudal without tho diapophyses, distal, antero-posterior diameter of the neural spine 0. 40 The points of attachnieut of the chevron-bones on the distal vertebrae are strongly-marked pits ; on the anterior, the anterior margins of the pits are raised and continuous with the chevrons. The muzzle presents the usual characters uf the large Mosasauroids, but adds a peculiarity in the prolongation of the premaxillary bone into a cylindric mass, forming an obtuse beak beyoud the premaxillary teeth. The bone is narrowed anteriorly, and does not descend regularly, as in Mosasaurm, sp., but continues to its abrupt and narrowed termination described. The extremity is deeper than wide. Immediately in front of and between the anterior premaxillary teeth, a short acuminate projectioQ interrupts the surface, and, in front of this, a transverse depression. Above, the surface becomes flattened, and presents two shallow longitudinal depressions con- tinuous with the nostrils. Where the premaxillary rather suddenly contracts into its spine, it is materially wider than the maxillary on each side of it ; in M. missuriensis it is narrower, according to Goldfuss. The maxillary border of the nares is rather suddenly concave at the anterior extremity of the nares, narrowing the maxillaries. The latter graxlually wulen by the expan- sion of their inner margins. No part of the fronlals is preserved, but a considerable part of the left prefrontal remains. It unites by a very coarse, overlapping suture with the maxillary, whose outline forms an irregular chevron, with the apex pointing forward in the middle of the maxillary bone. This, it will be seen, is very different from the form given by Goldfuss in the M. missuriensis, where the most anterior point of the suture is on the narcal margin. The external margin of the boue behind, is contracted considerably within the maxillary 164 border previous to its outward extension towai-c, nine. The quadrate bone of Z*. proriger presents a longer intejnal angle, and more prominent internal ridge, with smaller space inclosed by the basis of the great ala. My statement, in a pul)lished letter to Professor Lesley, that the ends of the mandibles were acute, thus dilTering from h. proriger, is an error, due to my having inadvertently mistaken the i)al- atines for the dentaries while writing. The posterior extremity of these bones iu L. proriger is unknown. The only species whose dorsal vertebrae are known to resemble, in the stoutness of their form, those a^ L. dxjspdor is the h. crassartus; the manifold differences of the latter will be at once discovered on reading the description already given. Measurements. M. Atlas, length of tlio inner articular face _. 0. 0G5 Atlas, length of the posterior articular face 0. 0.')4 Atlas, depth of the posterior articular face 0. 037 Axis, length at the middle of the side 0.075 Axis, depth anteriorly J 0.081 Axis, elovation of the neural spine 0. 075 Axis, width of the neural spine (plane) 0. 045 ^xis, diameter of the ball, vortical 0.070 174 M. Axis, dianicterof tbo ball, borizontal -'. 0.070 Corvical, diamoter of the ball, vertical 0. 006 Cervical, diameter of the ball, borizontal 0. 07() Cervical, leugtb 0.090 Anterior dorsal diameter of tbe ball, vertical 0. 0G5 Anterior dorsal diameter of tbe ball, horizontal 0.0H7 Anterior dorsal lengtb below (witb the ball) 0.100 Anterior dorsal lengtb of tbe diapopbysis 0.047 Anterior dorsal depth of tbe diapopbysLs 0.040 Posterior dorsal leugtb of tbe centrnm 0.097 Posterior dorsal diameter of the ball, vertical 0. 07G Posterior dorsal diameter of the ball, borizontal 0. 105 Posterior dorsal height of tbe neural spine (of another) 0.120 Lumbar, length of the centrum 0.090 Lumbar, diameter of the ball, vertical 0.073 Luml)ar, diameter of tho ball, borizontal 0.090 Lumbar, length of the diapopbysis 0. 09G Caudal (anterior), length of the centrnm 0.073 Caudal (auterior), depth of the ball, borizontal 0.085 Caudal (anterior), depth of tbe ball, vertical 0.075 Caudal (anterior), Icugthof the diapopbysis 0. li.'0 Caudal (posterior), lengtb of the centrum 0. 0G7 Caudal (posterior),lengtb of tbe diapopbysis 0.100 Candal (posterior), height of tbe neural spino 0. 087 Caudal (posterior), diameter of the ball, vertical 0.080 Caudal (posterior), diameter of tbe ball, borizontal 0.084 Maxillary bone, leugtb O.fi.'iO Miixillary bone, lengtb of the bases of two of the teeth (largest) 0.090 Mandible, depth behind the cotylus 0.110 Mandible, length behind the cotylus 0. 110 Width of tbe nasal septum 0. 0'31 Length of the palatine on the tooth-line 0.380 Depth of the palatine at tho third tooth from the front 0.039 Quadrate, length 0- 1^>0 Quadrate, length of the proximal internal angle .- 0.029 Quadrate, width of tbe face from the meatus to the external ridge 0. 029 Quadrate, width of tbe area of the basis of tboala 0.040 Quadrate, width at the condyles 0.070 Scapula, height (axial) • 0.120 Scapnla, width 0.183 Coraeoid, width 0. 187 Coracoid, length 0.200 Coraeoid, thickness at the cotylus 0.027 Humerus, lengtb .- 0. 189 Humerus, proximal width 0. 120 Hnmorus, distal width 0. 127 Ulna, length 0.179 Ulna, width, proximal - 0. 115 Ulna, width, distal 0. IIG Ulna, thickness proximally , 0. OGO Pubis, lengtb 0.245 Pubis, width, proximal 0.039 Pubis, width, distal 0.178 Ilium, length on the cnrvo - - 0. 350 llinm, width, proximal - 0. 018 Ilium, width, distal 0.087 Ischium, lengtb (straight) 0.195 Ischium, lengtb to the posterior process (axial) 0.123 175 M. Iscliitun, width, ]>i()xiiii;>l 0. •K') Iscbimn, wiillli, ilistal 0. 07r) Fciiinr, Icii'^tU _ 0. 185 Femur, width, proximal 0. 0!)3 Foumr, widtli. median 0. 0G4 Femur, width, distal 0. i;iO Fibnla, Um-xth 0. IIG Fibula, widtli, proximal 0. 100 Fibula, widtli, distal 0. 118 Fibuhi, [UDximal thickness 0. ().')2 Fibula, median width 0. OSO Tibia, leu'jth t». 10;{ Tibia, width, pnixiuial •. 0. (I4r> Tibia, width, median O.dvTj Tibia, width, distal 0. U,V2 Tibia, thickness, proximal 0 Ul'i Tibia, thickness, distal 0.0'M Phalange (posterior), length 0. U-'O Phalange, terminal, length 0. U15 This specimen is one of the most instructive which has yet been tlis- covered, including, as it does, fifty vertebrsE from all parts of the column, a large part of the cranium, with teeth, and both quadrate bones; the scapular arcli complete, except back of coracoid on one side; botli humeri, radius, and numerous phalanges of fore limb; the pelvic arch complete, with one hind limb complete to tarsus, with phalanges. The premaxillary is wanting, but the adjacent suture of the maxillary remains. Portions of a second individual of this species, or of L. proriger, were found On the Fox Cafion. They belonged to a larger animal, one equal to the New Mexican first described. Professor Mudge has fragments of still larger specimens. The principal specimen above described was excavated from a chalk bluff. Fragments of the jaws were seen lying on the slope, and other por- tions entered the shale. On being followed, a part of the cranium was taken from beneath the roots of a busli, and the vertebrje and limb-bones were found farther in. The vertebral series extended parallel with the. outcrop of the beds, and finally turned into the hill, and was followed so far as time would permit. It was aliandoned at the anterior caudal vertebrae. The outcrop of the stratum was light-yellow. The concealed part of the bed was bluish. Yellow chalk left on the specimens in thin layers became a white, or nearly so. The yellow and blue strata are definitely related in most localities, the former being the superior; but in others they pass into each other on the same horizon. In instituting a comparison between this and other known MosnsnurldcB, 176 it will be necessary to consider species referred to Mosasaurus as well as to Lio(lo7i, from the fact that some of the former may really be Lit)dons. The Liodoiis with compressed or round dorsal or lumbar vertebras may be dis- missed from comparison. Of the depressed species, L. pcrlatu.s, Cope, is known from specimens of one-third or less the size of the present one, which are further peculiar in having the diapophyses of the lumbars to stand on the anterior half only of the centrum. Among Mosasauri with depressed vertebral centra, it is to be noted that none present so great a degree of depression and I'ateral extension except the M. bnimhyl of Gibbes. They are all also much smaller. The M. hrumhyi was founded by Dr. Gibbes on two lumbar vertebrae from the Cretaceous of Alabama, which resemble those of the AI. dyispelor in form, and also in size. It is probably its nearest ally, and may be a Liodon. Dr. Gibbes established the genus Amphorosteus for it, but without sufficient evidence to support it. The principal point of distinction between it and the L. dyspelor which I observe is the lack, in the former, of the strong emargination of the superior margin of the articular surface for the floor of the neural canal, which is so marked in the latter. I have only the figures of Gibbes to rely on fi)r this l)articular, and it is scarcely probable that the artist would have overlooked it had it existed. Should the bounding prominences have been worn ofl^, then tiie restored centrum would have had a notabl}^ greater vertical diameter than in the L. dyspelor in the same portions of the vertebral column. As a second character, I note that, relying as before on Gibbes's figures, the external angles of the depressed ball are not so extended laterally in M. hrumhyi. In size, the vertebrae of the present animal exceed those of the M. hrumhyi. The latter has been hitherto the largest known species of the oriler Pythonomorpha, exceeding twofold in its measurements the M. gigun- teus of Belgium. So the present saurian is much larger in dimensions than the New Jersey species I have called M. maximus. If, as appears certain, the Mosasauroid discovered by Webb measures seventy-five feet in length, and the M. maximus measured eighty, the M. dyspelor must have been the longest reptile known, and approaches very nearly the extreme of the mam- malian growth seen in the whales, though, of course, without their bulk. Such monsters may well excite our surprise, as well as our curiosity, in the inquiry as to their source of food-supply, and what the character of those contemporary animals preserved in the same geologic horizon. 177 The Idcnlily wliciicr lliis reptile was first procured is near Fort McRac, in New Mexico. It was discovered by Dr. W. B. Lyon, surgeon at that post, and by him sent to the Army Medical Museum, at Washington, whose director placed it in the collection of the Smithsonian Institution. The attention to the paleontology of his neighborhood by Dr. Lyon will always be cause of satisfaction to students, and his name will be remembered with that of Turner (discoverer of the Elasmosaurus ])latyurus, Cope), Sternl)erg, and others. LioDON NEPJt:oLicus, Cope. Rhamphosaunis nepceoHcus, Cope, MS. Represented by the niandil)ular and parts of the maxillary and premax- illary bones, the quadrate, a dorsal vertebra, etc, of a single individual. These all indicate an animal related lo the large L. proriger, l)ut not more ihan one-third the size or less. It is about the same size as the L. micromus, Marsh, but is much more like the L. proriger in characters, so as to rcnd(!r it important to ascertain whether it be not a young individual of that species. An examination having convinced me that such is not the case, the points of distinction will be given farther on. The premaxillary is very prominent, forming a rostrum, whose inferior face is narrowed, and suddenly descends to a prominent transverse ridge, which bounds the anterior alveoli in front. The four premaxillary teeth stand on an area a little broader than long. Extremity broken. The anterior suture of the maxillary is vertical and zigzag. It displays a lateral contrac- tion just, behind the first tooth; while the anterior margin of the nostril is above the third tooth. The teeth of both jaws have broadly oval bases, and apices with two cutting-edges and lenticular section. The inner face is more convex than the outer, most so in the anterior part of the jaws, and neither is faceted. The enamel is finely striate-grooved, especially toward the base. The mandible is light and thin, and diminishes in depth posteriorly. The coronoid is small, and tlic angle is produced backward and but little down- ward. Tlu! rami are not complete; the large portions preserved exhibit teeth at intervals of precisely an inch. Professor Mudge, who discovered the specimen, states that the jaw, when together, measured twenty-six inches in length, wdiich would leave thirteen inches lor the dcntary bone. This is not flir from the true number of teeth. The quadrate resend)les that of /.. di/spdor in various respects. The 23 c 178 internal longitudinal ridge is very prominent, and extends from the proximal angle to the distal articular face in line with the plane of the short acuminate hook. The great ala is narrow, and rather stout ; tlie proximal articular face slopes steeply outward. The stapedial pit is a narrow, straight groove (per- haps partly closed by pressure). The knob is represented by a longitudinal crest, bordering the meatus below on the outer side, and not continuing to the distal articulation. The surface of the latter is crescentic, with an angle on the outer anterior bolder. This angle is the summit of a short, low, rugose ridge, which extends j)art way to the knob. Outer edge only of the great ala radiate-grooved ; posterior angle of distal condyle produced. The dorsal vertebra is somewhat flattened by pressure; but the ball was evidently transversely-cordate in outline. The bases of tlie diapophyses are very rugose : an angle from the articular cartilage is directed toward it from tlie rim of the cup. Inferior face with an obtuse median keel. The odontoid hone is deeper than long (fore and aft). As compared with L. micromus, this species differs in the much less attenuated premaxillary and maxillary bones, the anterior nostril, and absence of facets on the crowns of the teeth; from L. proriger in the absence of narrow concave facets on the anterior teeth, and anterior position of the nostril ; from L. dyspelor in the less compressed, or less knife-shaped, dental crowns, and totally different form of the condyle of the quadrate. Measurements. M. Leugth of tUc bases of the two i)reuiaxillary teeth 0.026 Width of the bases of the two premaxillary teeth 0.034 Length of the bases of the two maxillaiy teeth 0.042 Depth of the anterior suture of the maxillary 0. 028 Depth of the maxillary at the end of the uarcs 0.038 Length of the quadrate 0.082 Length of the distal condyle 0.040 Width of the distal condyle 0.017 Width of the great ala on the inner side 0. 032 Width of the inner face above the meatus 0. 0.!7 Length of the hook from the stapedial pit 0.028 Length of a dorsal vertebra 0. 009 Diameter of the ball, vertical ., ^.^~j Diameter of the ball, transverse 0.048 This species was discovered by Prof. B. F. Mudge, who dug the type- speciineii from the gray shale of tlie Niohrara Cretaceous, half a mile soutli of the Solomon River, Kansas. 179 PISCES. LITERATURE OF THE SUBJECT. 1856. Lcidy, Proceedings Academy Philadelphia, p. 73. Lcpidotus- from Judith River. Leidy, /. c, p. 256. Two species of Enchodus and Cladocydus de- scribed. Leidy, /. c, p. 312. Mrjlognathus priscus, from the Fort Union epoch, described. 1857. Leidy, I. c, p. 167. Phasganodus dims described. 1858. MarcoLi, North American Geology, p. 33. Ftychodus lohippleyi de- scribed. 1868. Leidy, Proceedings Academy, Philadelphia, p. 207. Ftychodus occi- dentalis described. 1870. Leidy, /. c, p. 12. Xiphactinus audax described. Cope, Proceedings American Philosophical Society, p. 529. Family of Saurodontidcs established and defined, and one new genus and four new species described. Cope, Hayden's Report on Geological Survey of Wyoming, p. 424. Apsopelix sauriformis described. 1871. Cope, Proceedings American Philosophical Society, p. 170. Genera Portheus and Anogmius described. 1872. Cope, /. c, p. 327. Descriptions of twenty species and nine genera; characters of latter and of families Saurodontidcc and Strato- dontklce extended. Cope, Proceedings Academy, Philadelphia, 280. Erisichthe nitida described. 1873. Leidy, Vertebrate Fauna of Western Territories, in Hayden's Report of United States Geological Survey, vol. I, p. 288. Twelve known species redescribed and figured. Cope, Proceedings Academy Philadelphia, p. 337. Portheus ieslrio and P. gladius described, and genus Daptinus defined. 1874. (April.) Cope, in Hayden's Bulletin of United States Geological Survey of the Territories, p. 39. Synopsis of all tlie species ; ten added ; genus Empo more fully defined. 180 1875. Cope, Proceedings Academy Philadelphia (January). Gar-fishes in Fort Union beds of Milk River. In the present work, the families, genera, antl species are more fuliy defined than has been heretofore practicable. ? PEECESOCES. SYLLiEMUS, Cope. Allied to the MugUiflce. A short spinous dorsal fin; ventral fins abdom- inal, posterior to the spinous dorsal. Pectoral fins subinfcrior in position. Coracoid bones forming a compressed, keeled body. Scales large, cycloid ; lateral line present, extending along the middle of the sides. Parietal bones less than epiotics, entirely separated by the supraoccipital. Frontal bones large, wide, their common suture distinct. The opercular apparatus extends obliquely backward, while the man- dible is produced forward. Hence, the inferior part of the hyoniandibular and the symplectic are directed obliquely forward. The eiul of the muzzle is broken off, but the posterior part of the dentary bone does not exhibit any teeth. The opercular bones are thin, and their inferior borders reach the median line of the inferior side of the head. The only species of this genus which has fallen under my observation is represented by a specimen in which the body posterior to the femoral bones is wanting. The surface is covered with scales, so that only the out- lines of the femoral bones can be distinctly seen. These are thickened, and curved outward ; those of opposite sides are well separated from each other. The scales exhibit a very delicate concentric line-sculpture. The very posterior position of the ventral fins distinguishes this genus from Mugil, while the inferior position of the pectoral fins is not seen in Atherina. The lateral line does not occupy the inferior position seen in the Scombreso- cidcB. As compared with Apsopelix, Cope, from the Benton group of Kansas, %//«??«MA- differs in the absence of continuous dorsal radii or interneural spines anterior to the ventral tins. There is doubtless some affinity between the two genera, as the other characters arc quite similar. I was unable to detect a lateral line in Apsopelix. It is possible that a catalogue-name of Agassiz, viz, Calamophurus (Poiss. Foss., V, p. 122), refers to this or some allied genus; but I am unable to discover that it has ever been described. 181 ~ SyiJ-.ii:MUS LATIFRONS, Cope. Keprcsciiied \)y tlic entire 1ic;kI and liody ol' a fish as far as tlic l)asis of tlic ventral fins, excei)ting the end of the muzzle. The scales are com- pletely j)reserved, while only the bases of the fins remain. Tin; l)ody is subcylindrie, while tin; head is broad and flat above. The inferior side of the head is contracted; the coracoids forming a keel, and the lower borders of the dentary bones being in contact. The angular portion of the dentary is strongly grooved on its inferior surface, and the proximal or anterior parts of the operculum display a radiate sculpture. The top of the head is smooth, excepting a slight radiate sculpture of the parietals. The outline of the parietals is subround, and a little more extended than that of the siipraoccipital, wliich is a short longitudinal oval. There arc twenty-six or twenty-seven longitudinal rows of scales, or thirteen on each half; tlio.-^e of the abdomen not differing from fiiose of the sides. The lateral line runs along the eighth below the dorsal fin, originating just'above the base of the pectoral fin. There are nine rows of scales between the occi[)ut and the first dorsal ray. I count the bases of fifteen dorsal radii, which are all fissured anteriorly, excepting the first, which is rudimental. The anterior rays are stouter than the posterior, and they embrace the pos- terior part of the ray in front of them by the basal fissure. The posterior rays are mucli narrowed, and embrace l)ut little. The pectoral rays are namerous. The physiognomy of this fish is rendered peculiar by the depressed form of the snout, with the narrow under jaw. It is impossible to be sure whether the muzzle was elongate or not. Measnreinents. M. Lciij;tli of the s)peciiiicn (o the l)a.so of tlio veutral liii ('. '*05 Lcimlli (>f tlic specimen to flic base of the dorsal 0.090 I.ciigtli of tlio .'.pccinii'ii to tho base of the pectoral ". 'i7."> Length of the ppecinicii to the edge of the operculum 0. 071 Length of the specimen to tho eilgo of the preopcreulum CO.").') Length of the specimen to tho condyle of the mesoptorygoid 0.021) Lcngtli of tho specimen to the orbit 0.017 Diameter of the front between the orbits 0.020 Diameter of the body at the middle of the dorsal tin 0. 04.''> Depth of the body at the middle of the dorsal fin 0.050 The specimen was found by Lieut eiianl Marsiiall, of the AV heeler United Stales Geographical Survey, "near the siimmif of Pike's Peak," Colorado. The specimen has the appearance ol' having been derived iioui tiie Cretaceous 182 or possibly Juraspic beds at the base of this granitic mountain, and its occur- rence where found was doubtless accidental. PELECORAPIS, Cope, gen. vov. This genus embraces tishes with strongly ctenoid scales and abdominal ventral fins. There is a spinous dorsal fin, apparently short, and not continued over the ventrals. The ribs and apophyses are slender, and {\\c dorsal ver- tebrae short and pitted. The ])uljic bones consist of two antero-posterior plates, in contact on the middle line. The anterior portion i)r()jects to a median angle, and there is an angular projection of the lateral border. From the angle formed by these borders, a long, cylindric rod projects forward beyond the plate ; those of opposite sides slightly converging. The general relations of this form are to the tiimilies which combine the features of the orders of physoclystous and physostomous fishes, viz, Scom- hresocidcE, Afheriniclce, etc. The pelvis has considerable resemblance to that of those families, I)ut especially to that of Exocosius. From this it presents subordinate ditferences. PeLECOKAPIS VAKIUS, S]>. 7100. Represented by portions of perhaps two individuals, the larger of wiiich includes a considerable peart of the body, the head and tail l)eing absent. On this specimen, it is evident that the scales diminish in size toward the posterior part of the body, where they are small ; on the anterior region, there are two scales exposed, in an oblique series, in si.x millimeters; on the pos- terior region, three and one-half and four in the same. The concealed portions of the scale are sculptured with minute contiguous concentric grooves, without any radii. The exposed portion is thickened with a cementum-like layer, which is marked witii a few radiating lines of p(jres, which sometimes unite into irregular grooves. Teeth of the comb numerous and strong. Depth of l)ody at pelvis, 0"'.074 ; length of pelvis, 0"'.040 ; of lamina, (r.022 ; of rod, 0"'.022 ; greatest width of pelvis, ()"\()23 ; width at basis of rods, O^.OH; length of seventeen consecutive vertebrae, 0"'.105; diameter of a dorsal vertebra, 0'".007. Discovered by Professor Mudge in a lead-colored <'lny, [)rol)ably of the Benton epoc-ii, twenty feet l)elow the Iitnceramvs bed, two miles west of Sililev, Kansas. • 183 ISOSPONDYLl. SAURODONTIDyE. This family cmUraces caniivumiis fislics, many of. them of large size and interesting structure, which have as yet only been discoverea in the beds „f the Cretaceous formation. Tliey are of interest (o the student of com- parative anatomy, and also to the paleontologist, as they appear to have been the predominant type of marine fishes during the Cretaceous period m the North American seas, and to have been abundant in those of Europe. The characters already assigned to the family are confirmed by the new species discovered, and many additional ones added, as follows : The cranial structure can be nearly made out, and the following points may be regarded as ascertained. The brain-case is not continued between the orbits, and the basis cranii is double and witli the muscular tul)e open. There are no exoccipital condyles, and that of the Ixxsioccipital is a conic cup. The homologies of some of the bones that constitute the cranial trnlls are difficult to determine. The basioccipital is longitudinally excavated below. The exoccipital is probably a small bone, which embraces the basi- occipital closely, so that it is .litficult to say whether the lK.ne that joins the opisthotic below is the former or latter. The opisthotic has considerable transverse extent, and an articular surtacc behind, probably for the posttem- poral. The supraoccipital is keeled or longitudinally crested al.ove, and is preceded by, or continued into, a longitudinal median extension, whirocess of the parasphenoid. Superiorly, it bounds, with tiie pterotic and sometimes {Portheus) opisthotic, a large foramen. The pretnaxUlari/ hones are short, and form but a small j)ortion of the upper jaw. The ma.villary is elongate and simple. The hyomandibular is rather narrow, and does not ])rescnt an elongate support for the operculum. The symj)lectic is well developed, entering fiir into the inferior quadrate. The latter is a broad bone, large, in contact with the metapterygoid, which is itself a thin plate, nearly attaining the pterotic. In Portheus, the pterygoid is well developed as a Inoad plate extending to the inferior boundary of the orbits. The palatine exhibits a marked peculiarity in the genera of this fam- ily. It is a shortish bone, soon uniting postero-inferiorly with the ectoptery- goid, but .supporting as its supero-anterior extremity a body comparable to the head of a hammer. This malleolar body, as it may be called, is a short- ened cylinder, with one extremity articulated to the prefrontal and the other to the posterior superior of the maxillary facets. This gives the latter bone a firnmess of support unusual among fishes. It also probably permits, of .some movement of the maxillary in a horizontal plane, which, thougli small, would have the effect of considerai)ly expanding the gape of the mouth, tluis enabling tliese fishes to swallow large bodies, in the manner of the Mosasauroids of the same sea and epoch. The ectopterygoid is a large bone, and extends down on the front of the inferior quadrate. Neither it nor the palatine supports teeth in any of the known genera. The sclerotica of (he eye is ossilied in Portheus and Ichthyodectes. This cssificatiou does not cover tlie eye, is not a complete circle, and is unseg- mented. Little can be said respecting the hyoid apparatus in this family. Some superior branchihyals, preserved in Portheus thaumas, are short flat rods. Two long llat bones, in place between the dentaries of a P. lestrio, a[)pear to be the distal ceratohyals. They terminate in some crushed basihyals, and are covered with minute teeth en brosse on the inner faces and superior margin.s. No specimen exiiibits the entire scapular a?-ch, but several preserve the scapula witii adjacent parts; two, a Portheus and probably an Ichthyodectes, 186 display most of the elements in place, and several others exhibit the artic- ulation of the pectoral fin. In the genera named, the clavicle is a wide bone antero-posteriorly, and is connected with the epiotic by a strong osseous bar, and probably with the apex of the parietal by another bar. The posterior part of the arch between these connections is occupied by the stout scapula. Its posterior face is principally occupied by three convex articular facets. It sends a short laminar continuation downward behind the clavicle, and turns inward above, with a massive body at right angles to its long axis. This transverse portion is supported by the coracoid, which is a stout, flat rod, narrower than the clavicle, and is apprcssed to the inner face of the latter nearly to its distal end. Its posterior border is separated from the clavicle by a deep groove, but the anterior margins are continuous. Above, it incloses a large foramen with the exterior part of the scapula. It is not now possible to state whether there is any prsecoracofd (Parker; '^ spangen- s/wcA-," Gegenbaur) ; but the upper part of the bone here called coracoid occupies the position of the prsecoracoid in some fishes, articulating with the superior instead of the inferior extremity of the scapula, as is usual. Except iu the elevated position of the scapula, the entire arrangement approaches .that of the Siluroids ; but the inferior part of the scapular arch is not hori- zontal as in those fishes, but vertically compressed. The articular facets of the scapula are convex : the inferior and largest is oblique ; the median and smallest is situated behind the axis of the others. Behind the superior two, on the transverse part of the scapula, are two round foss£E, in line, adapted for the reception of the condyles of two basilar bones. The pec/oral Jin is composed of osseous rays, of which the first is much the largest, forming a powerful defensive weapon. As the fossils are found, a number of these rays usually lie in close apposition, edge to edge; but they are not coosified, and in life probably diverged in the usual manner, extend- ing the intervening membrane. Their component halves difier much in form, and are easily separated ; and, as they often occur in this condition, inex- perienced persons may be led to regard them as entire spines. The femoral bones, or those supporting the ventral fins, are preserved in specimens of Ichthijodectes and Portheus. They resemble those of many physostomous fishes, but present a number of characteristic peculiarities. Their posterior portion is massive and is expanded on the outer side to sup- port the facets for the ventral rays. They are also expanded on the inner side, and strongly united, in the case o^ Portheus, by suture. The anterior part of these bones is thinner, and consists of two parts, — an inner rod, and an outer lamina at the base of the rod. The rods, or styles, are directed (()rward, par- 187 allel to each other ; the lamina is turned outward and upward (see Plate XLV, fig. 7, and cut, fig. 9). In Iclithijodectes anaides, the outer portion of the lamina is extended backward as well as forward; in a species of Portkeus (fig. d.), forward only. The face of attachment of the ventral fin is infero- lateral, and in antero-posterior line with the anterior rod ; it is therefore within the line of the external margin of the lateral alu of the femur. The face is expanded in a vertical direction, and is suhround. Its manner of articulation with the spines of the ventral fin presents a close analogy with the corresponding articulation of the pectoral spines witii llie scapula, so far as regards the first rays. Thus, there are two plane articular facets, — the one superior, the other inferior. Between these is a prominent and narrow transverse tuberosity, which bears an articular facet directed partially back- ward. Behind this, instead of the fossse of the scapula, there is another tuberosity, which is directed posteriorly. Thus, there are four facets, of which the largest pair supports the diverging halves of the bhse of the first ventral spine. The middle tuberosity is probably in contact with a portion of the second spine; and the posterior tuberosity with the base of the tliird. I have alluded to the -ventt'al rai/s as spines, and such arc tlie first three. Whether there are additional spines is more than doubtful, as in Porlheus, at least, there are no other articular surfaces than tho-se described. A p;iir of ventral fins, found in relation with their lemoral supports, by Profigssor Merrill, and .sketched on the spot before removal from the rock, embraces only the three spines; the halves of the first being separated, as is oflen the case in isolated specimens. Whether additional soft rays existed is also improbable; but, if existing, they must have been very few, as the basis fitr their support, such as exists in SalmonidcE and otiier physostomous fishes, is absolutely wanting. It is therefore improbable that the internal basilar bone was similar to that in the above recent fishes ; though from the analogy of the pectoral fins, one would expect to find ventral basilars. There are two small bones in the specimen described, which, according to the sketch, occupied the position of basilars ; and such they prol^ably are. Each is an irregular discoidal body, with one, a concave facet on one side. The osseous condition of the ventral rays is a remarkable character it) fishes of the general physostomous affinities of the S(iiirodo)ilU}ce. It is a point of resemblance to the physoclystous or spinous fishes, for which the structure of the superior walls of the skull in some measure prepares us. A third kind of spinous ray was originally described by me as jiertaining to the Portheus thaumas, and had been previously referred by Professor Agassi/, to tlie genus Ptychodux (vide Poissons Fos.siles). This is coniposcd 188 of closely-appressed osseous rays of different widths, each of which is com- posed of narrow, oblique segments. The sutures of these segments are of different character in ahiiost every ray : being in the marginal ray en chevron ; in others, step-like ; and, in others, dovetailed (see p. 200, and Plate XLIV, fig. 4). I suppose this compound spine to belong to one or other of the borders of the caudal fin. The vertebrae in all the species certainly assignable to this group are, where known, deeply two-grooved on each side, besides the pits for the inser- tion of neurapophyses and pleurapophyses, except in the cervical region, where the lateral grooves are wanting. There are no diapophyses. The caudal vertebrae are rather numerous, but not so much so as in Amia, nor are they so much recurved as in that genus. Affinities of the Saurodontidce. — More perfect specimens received since the description of the cranial structure on p. 183 was printed, render it almost certain that the median bone of the superior cranial walls is a supra- occipital; that the parietals are produced upward into an angle (epiotic, p. 183) on each side; and that the epiotics (opisthotic, p. 183) form the postero- lateral angles of the skull. If this interpretation be true, there is no opis- thotic bone. It is quite possible to interpret the superior cranial structure of the Siluroids in the same way, while the arrangement is very different from that seen in Salmonidce, Cijprinidce, Characinidce, and Esocidce, where the opisthotic is present, and where the supraoccipital does not present any. such anterior prolongation. The structure of the scapular arch, if we except the position of the scapula, has much in common with that of the Siluroids; while the two basilars and double articulation of the pectoral spine are striking points of resemblance to the same group. As characters of more typical Physostoini, we have the maxillary arcade of the mouth, the form and position of tlie ventral fins, and the apparent absence of dorsal spines. The form of the bones of the mouth, the presence of symplectic, subopercular, and postfrontal bones, the basioccipital muscular tube, and the unmodified anterior vertebrae, distinguish the Saurodontidce widely IVom the Nema- tognathi, and ally them to the Isospondyli; and with the latter I have for the present allowed them to remain. It must not be forgotten, however, that the long supraoccipital and osseous vientral rays arc physoclystous charac- ters, and that the form and position of the femora arc much nearer to those of i?(?/o«e than to those of any jjliysostomous fish known tome. The three persistent vertcbr.ie of the caudal fin rec&W Snlmo, while (he dorsals nearly resemble those of the Clupeidce. The peculiar malleolus of the palatine bone is closely imitated by the Ponwlobus iJS&udoharengus (alewife) ; but in that 189 pscudolmrengus (alewifc) ; but, in that species it articulates posteriorly with a process of the ethmoid, instead of the prefontal. In the blucfish (Poiiiatomus saltatrix) there is a nearer approach ; here, the malleolus articulates with tlic prefontal and maxillary, but with the latter only by a squamosal joint. The same species betrays a resemblance to. this family ia the insertion of the teeth by roots in alveoli, but the roots are much shorter in the living genus. They are also accompanied by a series of foramina on the inner side of the dcntary, as in Saurocephalus. Six genera are enumerated below as belonging to this fi\mily, of which one, Erisichthc, Cope, is placed in it provisionally : Synopsis of genera. I. Jaws without foramina on the inner face below the alveolar margin : a. Teeth cylindric : Teeth of unequal lengths ; some of them greatly developed Porthcus. Teeth of equal lengths - Ichthyodcclcs. aa. Teeth compressed, knife-liUe : Teeth of unequal lengths; some of the anterior ■ greatly develojied Erisichthc. Teeth equal. Daptinus. II. Dentary bones pierced by foramina l)clow the alveolar border : Teeth with subcylindric crowns Saurodon. Teeth witli short, compressed crowns Saurocephalus. There are some other forms to be referred to this family, whose cliarac- ters are not yet fully determined. Thus, Hypsocbn, Agass., from the European chalk, is related to the two genera first named above, but, as left by its author in the " Poissons fassiles," includes apparently two generic forms. The first figured and described has the mandibular teeth of equal length. In the second, they are unequal, as in Portheus, to which genus this specimen ought, perhaps, to be referred. Both are physostomous fishes, and not related to the Sphyranidce, wliere authors have generally placed them. Retaining the name Hxjpsodon for the genus with equal mandibular teeth, its relations to Ichthrjodecles remain lo l)e determined liy liutlun- study of the H. Icvesiensis. 190 The view of tlie superior walls of the cranium given by Professor Agassiz presents characters quite distinct from what I have observed in PortJieus. A species oi Ichthyodectes, from the chalk of Sussex, England, is figured, but not described, by Dixon in the Geology of Sussex. A number of forms, erroneously placed by Agassiz and Dixon in the genus Saurocephalus, have been referred by Leidy to a genus he calls Proto- sphyrmia,^ with two species, P. ferox and P. striata. The latter much resembles a Saurocep/nilus, having equal teeth; while the former prol)ably includes several species, and probaldy genera. The teeth first referred to it resemble those of P. striata; while others resemble those of Portheus. An examination of the figures of the mandibles of some of these in Dixon's work, shows that the large antl small teeth occupy ditTercnt areas, separated by grooves, in a manner quite distinct from anything seen in Portheus; but it can scarcely be regarded as typical o[' Protos2)hyr(sna, which name, moreover, has never been accompanied by the necessary description. - Dr. Leidy applied the name Xiphactinus to a genus indicated by a spine in some degree like those regarded above as ventrals of Saiirodontidfe. Whether it belongs to any of the genera above enumerated, or, if so, to which of them, is a question which can only be settled by future investigation. The history of the definition of this family may be found in the follow- ing references: Proceedings of the American Philosophical Society, 1870, p. 529; Hayden's Survey of Wyoming, etc., 1871, p. 414; Proceedings of the American Philosophical Society, February, 1872. PORTHEUS, Cope. Proceedings oi' the Aincricaii Philosophical Society, 1871. p. 173; 1. c, 1872, Febriiarv. Teeth sulicylindric, without serrate or cutting edges, occupying the pre- maxillary, maxillary, and dentary bones. Sizes irregular; the premaxillary, median maxillary, and anterior dentary teeth much enlarged. No foramina on inner face of jaws. Teeth on the premaxillary reduced in number. Oper- cular and preopercular bones very thin. Cranial bones not sculptured. The fishes of this genus were rapacious, and, so far as known, of large size. They constitute the most formidal)le type of physostomous fishes known. Five species are known to the writer from the Niobrara Cretaceous of Kansas. These are represented by numerous fragments of many individ- ' Trausactioiis of the American Philosophical Society, 1856. 191 uals, which inchide large portions of the cranium, two almost entirely com- plete. Others embrace jaws, and one a large part of the vertebral column, with segmented caudal rays. In one, these rays were found with the cutting pectoral ray above described, while the simple flat ventral rays occur with ceveral specimens. In none have any traces of symmetrical spinous rays been found, nor strong interneurals capable of supporting such. In none of the more perfect specimens with crania have the segmented rays been found; but the fossil of P. thaumas, where they occur, is represented by a vertebral column and its appendages, which do not differ appreciably from those of P. molossus. In the cranium of this genus, there is a well-marked supraorbital rim. Each opisthotic forms a prominent angle, directed posteriorly on each side of the exoccipital. The parasphenoid is a stout and narrow bone, deeply emar- ginate behind for the passage of the muscular canal. It has a transverse expansion in front of the base of the prootic, which rests on a backward con- tinuation of the same. Tliis expansion is pierced behind by two round fora- mina. The shaft is abruptly contracted in front of the expansion, and is tri- gonal in section. The prefrontal extends downward and forward, and carries inferior and anterior articular faces for the maxillary; the latter vertically transverse. The postero-inferior portion of the ethmoid bears on its posterior extremity a concave articular face, which opposes that of the vomer. The floor of the brain-case in front of the prootics is supported by a vertical style, which is bifurcate above, and rests on the parasphenoid below. There are large thin supernumerary bones attached to the upper side of the distal half of the maxillary, as in various clupeoid genera. There is a chain of thin suborbital bones. The crest of the vertex /is compressed, and, in one, at least, of the species, greatly elevated and overlapped by a super- ficial thin bone, wiiich forms a laminar extension of the crest in front of it. There is neither enamel nor sculpture on the cranium in any of the known sj^ecies. Of the teeth in general, it may be added that their pulji-cavity is rather large at the base but rapidly diminishes in the crown. The mode of succes- sion is by direct displacement from below. The young crown rises into the pulp-cavity, and destroys the vitality of the crown wliile tlic root is absorbed 192 Niinieroiis empty alveoli are to be found in all the jaws of this genus, in which examination will often detect the apex of the crown of the young tooth. All the bones of the palatine arch are present in this genus. The ectopterygoid is curved and concave on its lower border; the pterygoid is, on the other hand, thickened and concave on its upper border, where it is also strongly beveled outward, forming the inferior internal boundary of the orbit. The metapterygoid is a large, flat, and thin bone, joining the greater part of the superior border of the quadrate. It does not inclose a foramen with the other bones of the arch as is seen in Characinid fishes. These bones are all in place on a block, which also contains pectoral spines o{ Por- theus. On another block of the same specimen, the bones of the cheek are exhibited in connection with the quadrate. One is a greatly-expanded, thin bone, with the middle portion of its surface coarsely pitted. It is adjoined by a much smaller laminar bone of an irregular, semi-discoid form, witli the middle of the convex side with three obtuse processes separated by fissures. The corresponding bone in P. molossus is figured in Plate XL, fig. 9. Tiie interoperculum is a subparallelogrammic bone, with an open sigmoid artic- ular surfice at one end. In P. imlossus, there are two short articular faces on the other end. There is, therefore, no doubt, a suboperculum, though I have not identified it. The proximal part of the hyomandibular of another large specimen displays a continuous narrow articular surface for the pterotic. The posterior portion is a protuberant condyle ; the middle jmrt narrower and con- cave; the anterior part truncate, and j)resenting forward. Not fur below the proximal end, on the 2^osterior border, is a condyle for the operculum. It is sessile and Fig. 9.— Femoral bones ami ventral fin of a fPoW/ifiis: "ot Very protuberant, and is a right-hand upper figure, from above ; lower figure, from vertical OVal in Outline. This the right side ; left-hand figure, from below. , , , i i i bone closely resembles the cor- responding one o{ Ichthyodectes anaides. An incomplete skeleton of another Portheus includes pectoral arch and spines, branchial arches, etc. The arches are extended posteriorly, and the inner surfaces of the branchihyal bones are covered with minute teeth en brosse, and support a few tuberosities. The branchial fringe is preserved, consifting of long and slender processes. 193 Tlie spine supported by the scapular arch in Portheus and Ichthyodectes^ is a defensive weapon. Proxinially, it presents a concave articular surface for the sca])ula, with a sliort hook-like projection bounding one end. A specimen in relation, but somewhat mutilated, exhibits a flat, discoidal basilar Ikmic, which is probably applied to one of the scapular facets. Two rod-like basilars are visible, and two round condyles, projecting from the mass at the base of the fin-rays, fit into the scapular cotyli. The principal spine is flat and curved ; the convex edge trenchant beyond the middle. Tlie posterior edge is obtuse but narrow, and exhibits a slight groove on one side medially. Proximally, there is a shallow rabbet, whose floor is transversely rugose. Several layers of the tissue of the spine beyond the l)asal portion are deli- cately longitudinally striate. The distal half is broken away. Length of fragment, 1 toot; width, 1.5 inches; thickness at middle, 5 lines. The largest pectoral spine of Portheus in my possession measures 2.75 inches in width.^ The vertebrae in this genus are rather short, but not so much so as in sharks. In P. thaumas, nearly eighty dorsals and caudals were preserved ; those without lateral grooves, or cervicals (the term not appropriate), are not numerous. There are not more than three vertebrae entering the caudal fin ; a fact which is difficult to determine, owing to the concealment of the terminal centra by bases of radii. There are seven liaemapophyses in the support, all flat except the first, which is like those anterior to it. The sec- ond is articulated freely to its centrum, and is wider than the others. Its condyle is characteristic, being double, and with a foramen between it and the produced extremity of the posterior margin of the bone. It is slightly se|)arated distally from the third, but the remainder are in close contact. The radii of the superior lobe of the caudal fin extend at least as far down as near the end of the third haemal spine from below. The structure of these parts in the P. molossus is as in the P. thmanas, so far as preserved. An outhne-restoration of this genus is given on Plate LV. The species of this genus may be distinguished as follows: a. Two preuiaxillary teetli : Maxillary arch thin, deep, with narrow anterior coiulylo ; large maxillary teeth Jive ; third uiaudibular tooth large, behind a cross-groove P. molossus. Maxillary large teeth three ; third mandibular small, without cross- groove in front of it P. thaumas. aa. Three to five premaxilhiry teeth: Maxillary arch stout, deep, with heavy anterior condyle ; larger teeth five P. Icstrio. Maxillary arcli thick and shallow ; larger teeth five P. mudgei. aaa. Pieniaxillaiy teeth unknown : Maxillary bono deeply concave ; small i'. arciuttus. • See Plato XLII, fig. 4. 194 PORTHEUS MOLOSSUS, Cope. Proceedings of the American Philosophical Society for 1871, p. 173. Represented by four individuals : one from Fox Canon, near Fort Wal- lace, with complete cranium, and many vertebrae and radii ; a second from another part of the same, with large part of cranium ; and a third and fourth from Lower Butte Creek bluffs, both with fragmeuts of cranium and other portions. In the first specimen, the jaws are perfect and dentition complete. The premaxillary is vertically oval, convex externally, nearly flat within, and more than half underlaid by an anterior lamina of the maxillary. The anterior or median margin is regularly convex, and exhibits no surface or suture for union with the bone of the opposite side. Its posterior margin extends obliquely backward to beneath the superior articular condyle of the maxillary, and has a ragged edge, though the suture is squamosal. Its superior margin is deeply inflected in front of the condyle, and then convex and thickened. The anterior margin is thick and rugose witli tubercular exostoses. There are but two teeth, which are very large, and directed obliquely forward ; the first is two-thirds the diameter of the second. The maxillary is a large laminiform bone, with the upper margin consid- erably thickened proximally, but much thinned distally. It is abruptly con- tracted at the distal two-thirds its length, apparently for the attachment of a supernumerary bone. The extremity is curved saber-shape upward, and has an acute toothless edge. The teeth are four small, five large, and eighteen small. These teeth, except the largest, have cylindric bases; the crowns (and bases of the latter) are slightly compressed or oval ; they are straight and regular, and lean backward. The middle one of the five is largest, being six times as long as the small ones, but little more than half as long as the large premaxillary or mandibular. The surface of the maxillary is rugose with small tubercles on its lower half, and has shallow grooves for nutritious vessels running downward and forward. The mandibular rami are short and deep, and have but little mutual attachment at the symphysis. They are not incurved at that point, and were bound by ligament only. There is no coronoid bone, and the articular is dis- tinct. It is short, of a rather irregular wedge-shape, and supports half the cotylus, above which it sends a short acuminate process. The angular has a prominent angle, like half an ellipse, somewhat contracted at the l)asc; below 195 it is a rough, prominent, muscular insertion. The l)one extends in a loiiij sword-shaped process, on the inside of the ramus, to l)eyond its middle; externally, it is soon covered by the thin truncate edge of" the dentary. This element is very large. From the angular it rises steeply to a coronoid process, which lias a slight outwardly-twisted eminence, and then follows a gently concave line to the symphysis. The teeth are as follows : Two large — a transverse groove ; tliree large; four very small; nine medium; and two very small — total, twenty. These teeth have straight cylindric-conic crowns, with cementinn without stri^ or facets. The larger are a litllc ((impressed. Measurements of the jaws ciud teeth. M. Length of the premaxillary boue ou the alveolar border 0. 04.') Di^pth of the premaxillary bono on the alveolar border 0. 09:J Thiclciiess ou the alveolar margin 0. 01(> Length of the crown of the second tooth 0. ()4i) Diameter of the crown of the same at the base 0. 014 Length of the maxilhiry bone from the premaxillary 0.270 Depth of the maxillary bone at the condyle 0. OSO Depth of the maxillary bone at the middle 0. 046 Length of the crown of the third large tooth 0. 028 Diameter of the crown at the base 0.011 Length of the crown at the second .small tooth from the large 0. 006 Diameter of the crown at the base 0.004 Length of the ramus mandibuli 0.350 Length of the angle 0.040 Length of the angular bone exteriorly 0. 080 Depth at the coronoid process 0. 112 Depth at the fourth tooth 0.080 Length of the crown of the first tooth 0. 038 Diameter of the crown at the base 0.011 Length of the crown of the fourth tooth 0. 055 Diameter of the crown at the base 0. 016 The opercular bones are thin ; the operculum broad ; the preoperculum rather narrow. The latter is without armature, and has some shallow grooves radiating toward the circumference. Length of bone vertically, 0'".245 ; radius from inner curve, 0"'.09. Tiie vertebrce display deep lateral grooves ; articular faces smooth. Length of centrum, 0'".028 ; diameter, O^.OrtS. The fan-shaped ha3mal spine, or second of the caudal fin, is like that of P. thauinns, but smaller. The last caudals contract in size very rapidly ; the cup of the penultimate, or last, is transverse diamond-shaped. The fragments of the saber-shaped veuiral apine display several layers of parallel striate dense bone; and the edge is tubercularly dentate, and one side is much more rugose than the other. At the base, one side is (lat, the other convex ; and there is a transversely rugo.se band near one edge. 190 The scales are thin ami cycloid, and, though largo, arc not reniarkaljly so for tlic size of the fish. They are not readily preserved. Measurements of the cranium. M. Length from the augle of the opisthotic to the anterior extremity of the ethmoid 0. ;'0 Length from the angle of the opisthotie to the front of the proiitic 0. 11 Length from the postfrontal to the prefrontal across the orhit 0.11 Length from the occipital condyle to the transverse process of the parasphenoid 0. 117 Length i'roni the occipital condyle to the bottom of the parasphenoid emargination 0.0.").') Length of the parietal hone on the outer suture 0.07 Width of the parietal boue at the middle 0. 014 Width of the parietal bone to the edge of the pterotic 0.07 Width of the frontal at the middle of the orbit 0.04 Width of the parasphenoid at the middle orbit 0.03 Length of tile inferior cpiadrate 0. 10 Length of the condyle of the inferior quadrate 0.03 Length of the symplectic 0.064 This cranium is figured on Plate xxxix. The gape of the mouth of the Fortheus wolossus extended the whole length of the cranium proper, and far beyond the orbits, since the maxillary reaches to opposite the occipital condyle. The orbits were large. The lower jaw was deep, and gave the countenance that bull -dog expression from which it derives its name. The body was stout and moderately elongate. A comjjlete cranium of u Portlieus, probably the P. molossus, for which I am indebted to my friend Professor Merrill, of Lincoln University, at Topeka, Kans., furnishes several points of interest previously unknown. The moiitli is nearly vertical, somewhat as in Osmeroides, while the vertex is sur- mounted by an elevated crest. Hence, the superior and inferior facial out- lines meet at a right angle at the muzzle. The eye is small, and there is a suborbital chain of laminiform bones. The elevation of the skull is 16.75 inches, while the length is only 12.75 inches. Cut 8, page 184, represents this specimen. PORTHEUS THAUMAS, Cope. SuuroccphaTua thaumas, Cope, Proceedings of the American Philosoiihical Society, 1870, November ; Hayden's Survey of Wyoming, &c., 1871, p. 418. This large species rests on a specimen without cranium, originally pro- cured by Prof. B. F. Mudge. The parts preserved are not distinguishable from the corresponding ones in two individuals obtained by myself in West- ern Kansas, which include the greater portions of tlie jaws and suspensorial apparatus. These indicate larger animals than those of P. molossus, and one of the most powerful of the physostomous fishes, rivaling in this respect many of the saurians, which were its contemporaries. 197 The distinguishing features of the species have been already pointed out. The premaxillary is an ol)liquely oval or subpcntagonal bone ; the suture, with the maxillary, is not toothed, and the anterior or free edge is smooth, not tubercular, as in two specimens of P. molossus. There are but two teeth, of which the anterior is immense, and the second little more than half its diam- eter. The maxillary is stout, and supports in front four very small teeth; then three very large, of which the median is largest. The teeth recom- mence very small and are closely placed in the same line ; but, as the extremity of the maxillary is lost, the number cannot be stated. The dentary is similar in form to that of the P. molofsus, but has rather more numerous teeth. Counting from the front, there are two large, one rather small; two large, and eighteen small and medium following; the smallest from third to ninth, inclusive. None of the crowns are preserved, but the alveoli are round, or nearly so. The large tooth of the premaxillary, if proportioned as in P. molossus, must have projected 0™.0755, or three inches, above the alveolus ; the fourth mandibular was but little smaller. Measurements of the jaws. Length of the premaxillary 0.075 Depth of the premaxillary 0.09 Depth of the maxillary at the condyle 0. 08 Thickness of the maxillary jusfc hehind the condyle 0.025 Length of the deutary O.'Ji Depth of the deutary at the symphysis 0. 08 The various portions o( cranial bones preserved are much like those of P. molossus, but stouter. The hyomandibular is nearly perfect; it is thin, but has a convex rib extending to its acuminate extremity at the postero-inferior angle of the metapterygoid and the superior extremity of the symplectic. The preoperculum is attached by a thickened grooved margin, and is not overlapped by the hyomandibular. It extends in a curved form round toward the condyle of the inferior quadrate. Three elongate bones, closely appressed, I suspect to be part of this bone, with the interoperculum and superior cera- tohyal adherent. The last is rather narrow, and with smooth distal articular surface, without suture. The superior branchihyals are a little like phalanges oi' Mosasaurus in form, being subsimilar and expanded at the ends, and much flattened. The parasphenoid is similar to that of P. molossus. The position oi' liu; hyomandibular is vertical to the axis of the l)asioccipital, the siiprrior part directed forward. 198 Mcastiremciits. II. Length of tbo basioccipital to tbo cuil of tbo muscular foranicu 0.077 Length of the hyomanilibular -. 0. 2G0 Lcusth of tbo inferior quadrate (obliquct) 0. 11:5 Leugtb of tbo condyle of tbo inferior quadrate 0. 03G Length of tbo preoperculum jireservcd 0.305 A portion of one of the flat unsegmented or ventral spines preserved exhibits an irregular rabbet on each edge of one side; width, 0"\042. The sclerotic bones are as already described. A second specimen is still stouter in proportions, as the following meas- urements show : Measurements. M. Diameter of tbo maxillary condyle 0.034 Diameter of the maxilla above, bobiad the condyle 0.033 Length of the angle of the jaw (exteriorly) 0. 050 Diameter of tbo paraspbenoid at the middle of the prootio 0. 03 Diameter of the dorsal vertebra (crushed) 0. 0G7 The diameter of the vertebra must be corrected by a little reduction. The largest fish-vertebrae I obtained may be here mentioned. They are peculiar in having numerous concentric grooves on the articular faces, as in Ischi/rhiza. They are otherwise as in this genus. Length, 0".04 ; diameter, 0".062. . A peculiarity of dentition is observable in the two specimens first described, and in less degree in P. molossvs. A considerable number of alveolas support no functional teeth (though included in our enumeration), but arc occupied at some point by successional teeth. In some cases, the mouth of the alveolus appears to be narrowed by ossification, even where the tip of the young tooth is in sight; in one case, so tar developed as to close up to the projecting apex. In other cases, the orifice is entirely stopped by the ossification, which presents the appearance of a scar with radiating lines of pores. The first specimen was discovered in a denuded area among the lower bluffs of Butte Creek. The flat cranial and jaw-bone occupied the summit of a cone of twenty or more feet in height, a relic of the ancient blue lime- stone strata spared from the surrounding denudation. The flat bones had shed oflT the water, which, running off on all sides, had formed the cone. Tii(! second specimen ca IVom Fossil Spring Caiion, near the remains of Platecarpus curtirostris. 109 This species is also represented by wholes or parts of from sevent}' to eighty vertebrae, with numerous neural and liaemal spines and fin-radii, and, perhaps, some ribs. There are no teeth nor cranial fraa:mcnts. The l)iilk of the vertebrae is double that of those of Daptimis phhhotomus. The vertebras present the usual two inferior, two lateral, and two supe- rior grooves — the last for the neural arch. There are no cervical vertebrae; for these characters show them all to be dorsals and caudals. The suture for the ueurapophyses forms a regular angulatc convexity projecting downward. The arch is not closed above anteriorly, and is expanded laterally, while the spine is directed very obliquely backward. The concavities of the articular extremities are equal in the dorsals ; but, in the caudals, one surface is much more deeply concave than the other, one being funnel-shaped, and the other nearly plane in a few. A number of consecutive vertebrae which represent the posterior portion of the caudal series are preserved One of these is fortunately the very extremity; and they demonstrate the tail to have been vertebrated or hetero- cercal, after the manner of Salmo. On the anterior three of the series, the lateral grooves have disappeared from the centra ; the neural canal is very small, and the spines are very massive and curved backward, but much less so tlian in the more posterior parts of the column; they are flattened, wider than deep, and in close contact with each other, except the anterior of the three, which presents a narrowed edge forward. The ha^mapophyses are Ihin, and suturally united to the centrum by a flat gomphosis. The terminal series eml)r;ices six vertebrae, which have a minute or obsolete nrural canal, l)ut haemal canal distinct, but apparently interrupted. The haemal arches are united to tlie centra by a rather smooth suture. The general direction of these vertebrae forms a light upward curve. The haemal spines are flat and laminar, and their margins in contact; they decrease in width and length to the end of the series. The neural spine lies obliquely backward, and has a narrowed anterior ridge, but stout shaft. The anterior haemal spine in place exhibits a subglobular base, like an articulation, and its shaft is wider than those posterior to it. It is a subtri- angular flat bone, with neck and subglobular extremity, which applies very well to a concavity l)etween the anterior pair of pleurapophyscs, but does not in that position preserve contact witli the aiitc'ior margin of the succeeding spine. One margin of the enigmatical bone is thin and divergent; tlie other 200 expanded laterallj' and straight. The latter gives olFa transverse prominence, like half a globular knob, before reaching the extremity. Just within the latter are two lai-ge foramina, which are connected with the extremity by a groove on eacl^^side, which meet in a notch where the thin edge passes into the knol). Both sides of the neural and hasmal spines are concealed in this species and in the Ichthyodectes jyrognathus by numerous parallel osseous rods, which are somewhat angulate in section. They lie along the centra of the anterior series of caudal vertebrae, but are not to be found on vertebrse of any other part of the column. Numerous loose and fragmentary rods of the same char- acter accompany the loose and attached caudal vertebrae, and all of them according to Professor Mudge, belong to the "posterior swimming organ" of this animal. There is also a collection of these rods from the anterior region of the body, which Professor Mudge thought occupied the position of an anterior limb. They do not, any of them, present a segmentation such as would be exhibited by the cartilaginous radii of caudal and pectoral fins, and their nature might have remained doubtful but for the explanation furnished l)y the anterior compound ray or spine of the posterior, probably caudal, fin. Tliis ray, as in the case of the pectoral spine and first anal rays of some exist- ing siluroid and loricariid fishes, is composed of a number of parallel rods closely united. These are in their distal portions remarkably and beauti- fully segmented, of which a very simple form has been figured by Kner, as existing in the pectoral spine of the siluroid genus Pangasius. This seg- mentation becomes more obscure proxiraally, and finally disappears alto- gether,- leaving the spine and rods homogeneous. This portion of them is quite identical with the rods found in tlie positions of fins already described, and I therefore regard these as fin-radii of the attenuated form presented l)y cartilaginous rays of most fishes, but ossified sufficiently to destroy the segmentation. They are thus in the condition of the anterior rays of the dorsal fin of some of the large CatostomidcR, or marginal caudal rays of some Ghnracinidce, where they are proximally homogeneous and bony, distally seg- mented and cartilaginous. The segmentation above alluded to presents the following cliai'aclers The spine consists of four principal parallel rods, of which the external on each side thins, the one to an obtuse, the other to a thin edge. The more obtuse edge presents a groove on one side, which is occupied by a very slen- 201 (ler rod, and a sliallow raljbet along the Hat edge is occupied by a slender flat rod. Of the tour principal rods, the two median are the most slender, and llie flat maririiial the widest. Of the two median, that next the latter is tlu; wider. Tlie stout marginal, or protiabl}' anterior, rod is segmented en chev- ron, tlie angle directed disfally and lying near the free margin. The suture of the resulting segments is entirely straight, except, when returning, it approaches tlie margin, where it suddenly turns to the margin at right angles to it. The next rod is segmented without chevron obliquely backward and inward ; where it leaves and reaches the margins, it is at right angles to them, and the margin projects obtusely at those points. Between the ends, the suture is very irregular and jagged, sending processes forward and backward. The segmen- tation of the next rod is similar, but more regularly serrate; distally, it becomes as irregular as in the last. The transverse marginal termini of the sutures are serrate in both. The inner and widest rod presents a still more regularly serrate oblique suture with the truncate extremities; but, owing to the width of the rod, the near approximation of the sutures continues for a longer distance. When broken, the suture appears steplike. Measurements. M. Length of a iiagmeut of the (?) caudal spiue 0.25 Width of the fragment at the iiroxinial fracture 0.06 Greatest thickness at the i)n)xiuial fracture 0.013 Width of the posterior rod at the proximal fracture 0. 0245 Ijenj|;tU of six distal caudal vcrteb:!0 0. 1(1 Width of tlie hicmal spine of the secoud of the series 0.024 Vertical erior elements of the pectoral fin are laminiform and concave on the side in contact with the inferior halves, which they somewhat exceed in width. The inferior halves are massive, and exhibit a strong superior rabbet on the posterior margin for an overlapping border of the second ray. On the anterior margin is a more shallow rabbet, which soon disappears, which is covered by the superior lamina. The posterior rabbet also disappears at a point varying with the species. The superior lamina bears the cotylus and adjacent hook, which embrace the suj)erior scapular facet; the inferior half supports the facets which correspond to the inferior two of the scapula. The front of the pectoral spine is sharp-edged, forming a thin blade, hardened by a deposit of dense bone, which is transversely roughened. The blade is the edge of the supe- rior lamina, which extends beyond the equally acute border of the inferior half, the latter fitting closely to the concave inferior face of the former. Both faces of the spine are covei'ed with a dense layer of bone, which is marked with delicate longitudinal grooves; and, when the superficial layers are broken away, the deeper ones are found to be grooved in the same 205 manner. This i)ectur;il si»iiic is a formidablo weapon, measuring between two and three feet in length and two inches in width in a Portheus thaumas whose mandibular ramus is a foot in length. The ventral rays considerably resemble the pectoral but are relatively weaker. The second and third are much smaller than the first, have a lonsriludinal rib on the side of one of the angles, and are scarcely flattened. The first is much flattened, and exhibits a sharp anterior edge, formed by the projecting border of the thinner half. The capitula of all the rays are strongly curved to a beak-like apex, bearing a tuberosity on the convexity in the two smaller ones. They differ from those of the anterior pectoral spines in the conve.xity of their articular facets, as they do not embrace the facets of the femur as do the pectorals those of the scapula. Like the latter, the dense superficial layer of bone is often finely striate-grooved. ICHTHYODECTES, Cope. Proceedings of the American Pbilosopbical Society, 1870, November; Hayden's Geological Survey of Wyoming, etc., 1871, p. 4'21. Teeth equal, suljcylindric, in a single row, sunk in deep alveoli. Premaxillaries short. No foramina at the bases of the teeth on the inner alveolar walls. Vertebrae deeply grooved laterally. The species of this genus are, so for as known, smaller than those of the last, and, as their remains are more perishable than those, form less striking objects among the fossils of Kansas. They are, nevertheless very abundant, especially in species, five of which are now described. The general structure in detail is much like that of Portheus. The maxillary l)one is not contracted distally for a supernumerary bone, as in Portheus. The quadrate is similar, and the symplectic has a wide exposure on its outer foce in /. amides. An entire anterior spine of the pectoral fin of/, anaides is preserved, the halves partially separated (see Plate XLV, fig. 8). The superior half is wider than the inferior, and projects beyond it, forming the trenchant anterior border, which is roughened by a deposit of dense osseous material. The inferior half is but little thicker, and has an acute posterior border; its surface is delicately striate-grooved. The spine; widens distally, and thins out to an oblique, irregular edge, and was doubtless con- tinued as cartilage. A ventral spine accompanies the Itones of /. prognafhvs and /. mu/ilde»taftts, which is of a more robust form than the above-mentioned pectoral, but not so wide. The vertebrae are deeply longitudinally grooved, as in Portheus, with the exception of a few of the anterior. 206 111 a series of vertebrse similar to those of" this genus, those included in the hasis of the caiulal fin are not more than three in number. The species are distinguished as follows : Premaxillary^ teeth 5, second most prominent ; maxillary not concave ; dentary with 30 teeth, and biconvex alveolar border, with obtuse extremity /. anaides. Premaxillaries ? ; maxillary straight, large, with 40 teeth; dentary straight, not produced at end ; teeth 26 /. ctenodon. Premaxillaries 5, first most prominent; maxillary concave, narrow ; teeth small ; dentary with a hook at apex, teeth 25 - /. hamatus. Premaxillaries 7, first most prominent, compressed ; smaller. /. prognalhus. Premaxillaries 12, second most prominent; the bone mucli narrowed above, smaller /. multidentaius. The English species of this genus is figured by Dixon in the Geology of Sussex, PI. xxxii, Figs. 9 and 9*. I can find no letter-press nor name relating to it, and cannot determine its specific characters from the fragment- ary character of the piece of mandible figured. ICHTHYODECTES ANAIDES, Cope. Indicated by two individuals: one with both dentary bones and teeth, with vertebrse; the other with many portions of cranium, fin -rays, vertebras, and other elements more or less separated. The latter were all taken from the upper face of a spur of a limestone-bluff, elevated about five feet from the ground-level, where they were denuded and exposed as on a table. It is the largest species of the genus, and the anterior premaxillary teeth are larger than«the posterior. The premaxillary hones are oblique ovoids, very convex on the external face, thinning laterally and above. The superior mar- gin presents a thickening bearing an articular surface, while behind it is an open gutter-like inflection. The large teeth are quite cylindrical. Both these bones are preserved. But part of the right maxillary remains. It is thickened above in front of tlie condyle, and is regularly convex at that point. The teeth are small, tiiere being 10.5 in an inch. The margin is not concave. The mandibular rami are preserved almost entire. They are short and deep, and have a short angular process, which is relatively shorter than in 207 Portheua. The margin rises steeply to the dentary, whieli presents a nar- rowed rectangle behind. The alveolar margin has two convexities, witli a depression between; the syniphyseal angle is not prominenl. The lower posterior angle of the dentary is quite prominent for muscular insertion. Tlie crowns of the teeth are cylindric, slightly curved inward. The dentary bones of the second specimen coincide with these in all respects. Thirty-three vertebra are preserved, all deeply two-groovcid on the sides. The ribs are articulated by a sigmoid surface to a l)road, short element of a sigmoid form, which is inserted in the lateral groove of the inferior face, or articulated by gomphosis. The ventral spines already noticed are quite flat, witliout serrate edge, but with some rugosities near the edge on one side only. There are no grooves on the upper side, but the dense bone is delicately striate. Measurements. M. Length of the prcnuixillnry 0. 033 Depth of the premaxillary 0.045 Depth of the maxillary at the condyle 0.037 Tliickness of the maxiUaiy just behind the condyle 0.012 Length of the mandibular ramus 0. 172 Length of the angular process 0. 014 Depth at the corouoid process 0. 0.")8 Depth at the symphysis 0. 04 1 Length of eight vertebnu 0.212 Width of the articular face 0. 0;;0 Width of rib 0.004 Width of the ventral spine .at the middle 0. 025 Length of the ventral spine (fragment) 0. l.'io Length of the condyle of t he inferior quadrate 0. 020 The scales associated with this species were tJiiii and cycloid, and diffi- cult to preserve. From near t!ie Smoky Hill Uiver, Kansas. IciITHYODECTES CTENODON, Cope. Proceedings of the Ainri icaii P]iili)sopliical Society, 1870, November ; H.ayden's Geological Survey of Wy- oming, &c., 1871, p. 421, part. Found l)r Profiessor Mudge on the North Fork of the Smoky Hill River; common in many other localities. This species is established on one complete maxillary bone, and three- fourths of the other, a large part of the dentary bone, witli tlu! entire dental series, and numerous portions of cranial bones. These, according to Profes- sor Mudge, were found together, and, to all appearance, belong to the same aniiuiil. 208 rpi he ilriiuil characters differ from those of Saurocepfialus, as aljove pointed out, and resemble more those of Saurodon leantts. The crowns of the teeth are more exserted and slender. The inner face of the crown is more convex than the outer; but there is no angle separating the two aspects. The apex is moderately acute, and directed a little inward, owing to a slight convexity of the external face. Enamel smooth. The alveoli are very close together, and are probably only separated in their deeper portions. There are forty-two teeth and alveoli in the maxillary bone. The superior condyle is low, and its anterior border falls opposite to the last tooth, or the indented surface wliich wns occupied by the premaxillary bone. The more proximal part of the maxillary curves inward and backward behind the position of the premaxillary, more than in S. inognathus. Tne maxillary is a rather thin and narrow bone, with a broad obtuse and thinned extremity. Its superior mar- gin is marked with one or more acute ridges, which look as though it had a contact with a large preorbital bone. The alveolar border is nearly straight. The dentary bone is remai'kable for its straightness and laminar charac- ter, and for the depth of the symphysis. The length of the latter is preserved, wliile posteriorly to it the lower margin of the dentary is broken away. The alveolar margin is slightly concave, and unites with the symphyseal at an angle of 65°. There are twenty-six teeth and alveolae, which grow a little larger to the posterior extremity of the series ; anteriorly, the alveoli are confluent externally, but, posteriorly, the septa are frequently complete, though thin. In neither this bone nor the maxillary are to be found the foramina along the bases of the teeth, characteristic of Saurocephalus or Saurodon, as pointed out by Harlan and Hays. Measurements. M. Ltfngtb of the maxillary bone 0. 158 Depth at the condyle .' 0.031 Depth at the extremity 0.022 Length of the crown of a tooth , 0. OOGl Diameter of the crown at the base 0. 00:>S Length of the alveolar border of the dentary 0. 106 Depth of the symphyseal border of the dentary 0.047 Length of the oper^nlar condyle 0. OlS Several osseous ventral rays accompany the cranial bones ; they are prob- ably interior in position, and are much more slender tlian the ventral spines observed in /. annides and /. prognathus. Tliey are subquadrate in section, not sculptured nor enameled; there is a shallow groove on the side. 209 ICIITIIYOUKCTKS HAMATUS, Cope. Represented by a considerable nnmbcr of nnnains of an indivith of tho maxillary at tlio condyle ^ 0. ((27 Depth of tbo maxillary behind the condyle fl. 02:i Depth of the maxillary near the middle (I. 0:i7 Width of the ventral spine 0. O.U This S2)ecies and the two preceding were not very unlike in size ; the two following are smaller. ICHTHYODKCTES PROGNATHUS, (JopC. Proceedings of tho American Philosophical Society, 1870, November {Sauiocephahis) ; Hayden's Geologi- cal Survey of Wyoming, &c., 1871, p. 417. In this species, the premaxillary is more rhomboid in outline than in the others, and is less convex externally. Of its more numerous teeth, the first is not larger than the last, differing thus from all others of the genus; it is in line with the nearly straight anterior margin of the bone, and is more com- pressed than in the other species. The surface of the l)one is peculiar in a minute sculpture of impressed lines, or lines oC punctae. There is a very small articular surface on the superior extremity. This species is represented by a premaxillary and attached proximal j)ortion of the maxillary l)oiies of the right side, and by a large number of ver- tebra; and other bones. These portions were associated in the collections placed in my hands by Professor Mudge, and relate to each other in size, as do those of the preceding species and the Ichthyodectes ctenodon. The premaxillary is characterized by its great depth as compared witli its length, and by the shortness of its union with the maxillary. The pala- tine condyle of the maxillary reaches a point above the middle of the alveolar margin of the premaxillary. The latter contains alveolae of seven tectli, the anterior of which only presents a perfect crown. It is elongate, compressed, equilateral, smooth, and acute. Its direction is even more obliquely forward than the anterior outline of the bone, which tself makes an angle of 50° with the alveolar border. The vertebrae consist of cervicals, dorsals, and caudals, to the number of about sixty, most of which are supposed to have been derived from the same animal. The grooves are as in D. phlebotoinus ; there being two below, two on each side, and two above. The latter receives the bases of the neu- rapopliyses, which are in many cases preserved. The inferior pair of grooves becomes more widely .separated as we approach the cervical series, leaving an inl'erior plane, which is longitudinally striate-grooved. This plane widens 211 till the grooves bounding it disap|)ear. The inl'erior lateral groove l)ecomcs widened into a pit, which some of the specimens show to have been occupied by a pluglike parapophysis, as in Elops, etc., or a rib-head of similar form. The neurapophysial articular grooves become pits anteriorly, and these only of all the grooves, remain on the anterior two vertebrae in the collection. Some of the posterior caudals pi'eserve large portions of the neural arches and spines. They form an oblique zigzag suture with the bodies, consisting of two right angles on each, one projecting upward anteriorly, another down- ward behind. The neural spines are very wide and massive, and in close contact antero-posteriorly ; these probably support the caudal fin. They are deeply and elegantly grooved from the basis upward. The centra exhibit no lateral grooves. An unsymmetrical ventral fin-ray accompanied these remains, and, from its mineralization, color, size, and sculpture, probably belongs with them. The anterior margin is thinned, and with obtuse denticulations; the posterior trun- cate. The section is lenticular, with a deep rabbet on one side of the posterior edge; section at the base circular, apex lost. The sculpture consists of fine, longitudinal, raised striae, which bifurcate and send numerous similar ridges to the teeth of the anterior margin. This ray difiers from the corresponding one of /. anakles in its greater relative thickness, its anterior rugosity, and peculiar sculpture. Measurements. M. Long diameter of tbe spine 0. 0^45 Basal diameter ot the spine 0. 019 Lengtli of two ceivicals (not distorted) 0. 033 Diameter of tlie anterior 0. 021 Length of a dorsal 0. 016 Length of a caudal 0. 014 Width of the nenral spine ef the caudal at the base 0. 01'2 Length of the alveolar margin of the premaxillary 0.022 Length of the anterior margin of the premaxillary 0. 020 Depth from the condyle of the maxillary 0.026 Length of the crown of the premaxillary tooth- 0. 0042 Diameter of the crown of t he premaxillary tooth 0. 002 A fragment of a large Hat bone exhibits very delicate radiating grooves, whicii are marked by spaced impressed dots. From the North Fork of the Smoky River, Kansas, six miles south of the town of Sheridan. Prof B. F. Mudge. This species was about two-thirds the size of the species last described. 212 ICHTHYODECTES MULTIDENTATUS, Cope. This species was first described from a preniaxillary aud part of a max- illary bone, from tlie Smoky Hill River ; a second and more perfectly-pre- served skeleton, obtained l)y Prof Merrill from tlie headwaters of the Solomon River, adds much to our knowledge of it. The first-mentioned specimen was described as follows: " In this fish, we have the cimwex premaxillary of the larger species, with more numerous (twelve) teeth than in any other of the genus. Those of largest size are the first three, the last being small. The second and third are about equally prominent, and more so than the first. The bone is much contracted above ; there being an excavation on the anterior border, and con- traction from behind. The superior edge is thin, and without trace of artic- ular surface. Alveolar edge somewhat rugose. The maxillary is both narrow and thin, but is only partially preserved. It bears five teeth on O^.Ol. One of these, with complete crown, displays a longitudinal angle on the antero-interior face. Length of the premaxilku-y, 0".039 ; depth of the premaxillary (oblique), O-.O'ZS ; length of its tooth-line, C^.Q-ZS." The second specimen is represented by a cranium with maxillary bone and scapular arch, vertebrae and ventral spines, etc. The specific characters are well exhibited in the dentition. There are thirty teeth and eighteen empty alveoli in the maxillary bone; and the anterior apex of the same, which is l)roken off, probably supported tour additional ones. The crowns have a subround section, and differ from those of other species in being marked with shallow sulci and longitudinal angles and ridges. The most prominent ridges are, one on the middle of the external face, and one on the outer side of the anterior face, but there may be two or three on the outer face and on a few posterior teeth ; the outer face is smooth. The fragment with tooth, above described as typical, belongs to the distal part of the jaw. There are shallow grooves at the bases of the crowns of most of the teeth. The cranium has an elevated crest, which stands on the narrow median bone which I suppose to be supraoccipital. On each side, and just behind the crest, the parietal bone rises as a posteriorly-directed process The epiotic also forms a strong latero-posterior angle. The pterotic extends roof- like on each side; its anterior part abruptly depressed below the posterior. The postf rontal forms a short transverse process, which is preceded by a con- cave excavation of its free border. The vertical position of the malleolar process of the prefrontal shows that this species possessed the subvertical mouth already ascribed to the Portheus molossus. The scapula is much like that of Portheus, and in the specimen stands on a level with the orbit. The ventral spine is of relatively large [)ropor- tions, and its superficial dense layer is marked with rows of delicate, im- pressed punctse, which are sometimes confluent into grooves. The first cervical vertebra is unmodified aud grooveless ; the dorsal vertebrae are grooved. Length of cranium, 0".154; diameter of first vertebra, U™.020; depth of maxillary at middle, U'".()23 ; width of ventral spine, 0".020 ; length of articular face of scapula, 0"'.031 ; width of clavicle below scapula, 0"'.U4U. 2KT DAPTINUS, Cope. Tliis gcims was proposed for Saurocephalus phlehotomus, Cope. TIk; (oiiii of the crowns ol' 1 he tcelli is {\n\{ ot' Saurocejfhaliis and Erisichlhc; l)ii( if differs from tlie lattcjr in llicir perfect ecpiality of size. It differs from the fomier in the position of the nutritious foramina of the inner si(h; of the dcntary hone; for, instead of forming an isohited series, as in tha( genus, tliey only appear as notches on the inner margins of the alveoli. The mode of articulation of the premaxillary and maxillary hones wilh each other and with the prefrontals is similar to (hat already descrihcd in the genus Portheus. The maxillary underlaps the premaxillary on its inner face, forming a very extensive squamosal suture, and pres(!nts the two superior condyles, the anterior for the ethmoid, the posterior for the palatine hones. The palatine presents the malleolar segment which connects the maxillary ami prefrontal articular faces, and then continues downward and hackward, as a vertical lamina, without teeth on its free margin. Immediately in front of eacli of these hones is a triangular element, compressed, with an acute apex upward and truncate base downward, the posterior border in contact with the anterior edge of the palatine. The vomer is toothless. The anterior vertebrae present pits tor the neurapophyses, l>ut no others, as far as the third. On the fourth and subsequent c(;ntra, tlicrc is a deep lateral pit, and a smaller one above and behind it, near, and a little posterior to the neurapophysial pit. The teeth in Daptinus arc not a little like tliose of the existing genus Fomatoimts, which includes the bluefish. Daptinus pulebotomus. Cope. Represented by all the tooth-bearing elements of three individuals, from- distinct localities, with portions of crania and vertebra'. These show that the jaws are long and slender, and that the teeth are closely set, and with the roots l)ut little compressed, while the crowns are very much so. Eight alveolae may be counted in fourteen millimeters. The dentary bones have a vertical and transverse truncation at the symphysis, and are thickened so as to afford strong attachment for something ; the absence of the usual oI)li(juity in the one or the other direction is noteworthy. The teeth continue to the symphysis, but of slightly reduced size. The internal groove of the dentary 214 is deep, and continued to near the symphysis. The cotylus of the articuhir bone is j)rescnved largely backward. The prcinaxillary is a large oval plato, gently convex on the outer side, and of greater vertical than transverse extent. It differs from that of Porlheus in lacking the condyle on the superior border. In the best-preserved speci- men, a large piece is broken from its posterior alveolar border ; in that which remains, nine alveoli remain. In two of the specimens, the anterior part of the cranium is preserved. The anterior part of the ethmoid is broad and convex above, and rapidly contracts to an acute, flat apex. Laterally, it overhangs the fossa in whicli the anterior maxillary condyle enters, atul furnishes a flat surface for the posterior condyle of the same bone. The vomer is excavated laterally in front, .so as to be somewhat cross-shaped, the apex being rather produced. It is edentulous. Measurements. M. No. 1, depth of the iirom.axillary 0.054 No. 1, depth of the maxillary at the middle 0.025 No. 1, depth of the triaugiilar bone of the palate 0. 038 No. 1, depth of the aympbysis of the mandibuli 0.026 No. 2, length of three anterior vertebra; « 0.040 No. 2, diameter of ouc anterior vertebra - 0. 010 No. 2, depth of the dentary 0.041 No. 2, depth of the .symphysis 0. 02G Fo. 2, width of the ethmoid aliovo 0. 0105 No. 2, width of the craiiinm at the i>refroutal facets 0.022 No. 2, length of the muzzle to the prefrontal facets 0.023 A third specimen consists of some vertebrae and portions of the cranium; the latter including the dentary, maxillary, part of the premaxillary, the palatine and vomerine bone;?, compressed into a mass by pressure, the separate pieces preserving nearly their normal relations. From the, latter, the following characters may be derived : Palatine bones toothless; teeth of both maxillary and dentary with compressed crowns, wiiich are longer than wide at base, and closely placed; those of the dentary twice as large as those of the maxillary. Maxillary bone proximally deep ; dentary shallower; the maxillary with elongate suture with the premaxillary behind. The teeth are equilateral, without intermarginr.l groove or barb, and with smooth enamel- surface, or only minutely striate under the microscope. A series of larger foramina extends along the alveolar margin of the maxil 215 lary and dciitary bones, one loranicn 1«) each tootli. The alveolae are confluent as they approach this margin. There arc three vertebrae, which present two pairs of deep longitudina grooves, viz, two on each side, two on the interior, and two on the superior face of the bone ; the last receives the basal articulation of the ha3niapophyscs. The centra arc crushed. Their nieasureinents, witJi thos(^ of the jaws, are as follows : ifcavurcments. M. Length of the cciitruui 0.025 LoDg (liatnctcr (crusbcd) 0. 035 Short diameter (crushed) 0.0175 Depth of the maxillary bono .'vntoriorly 0.031 Depth of fho dentary bone anteriorly i 0.015 Length of thu crown of the inferior tooth 0. OOG Length of the crown of the superior tooth 0. 004G Number of inferior tooth in O^.OI, :! ; number of aupcrior teeth in O'^.Ol, 4.5. The vertebrae arc about as largo as those of a fully-grown "drum-fish," Pogonias. From the yellow chalk of the Upper Cretaceous of Kansas, found on the Solomon or Nepaholla River, Kansas, at a point one hundred and sixty miles above its mouth, and in Trego and Rooks Counties, by Prof. ]J. F. Mudge, jn'ofessor of natural science in the State Agricultural College of Kansas. SAUROCEPHALUS, Harlan. Leidy has pointed out the mode of implantation of the teeth in the typical species of this genus. The mode of succession of the teeth has not yet been indicated, but is well displayed in a specimen of the jaw of 6". ara- pahovms. Cope. It is known from Harlan's description that a large Ibramen issues on the inner wall of the jaw, opposite each root. The fractured ends of the specimen exhibit the course of the canal which issues at this foramen. It turns abruptly downward between the inner wall of the jaw and the fang of the functional tooth, and not far from the foramen. Its course is inter- rupted by the crown of the successional tooth. This is situated obliquely as regards the long axis of the jaw. It is thus plain that the successional ap|)earance of teeth is different in this genus from what I have described in Portlieus and Iclithyodecles. In them, the foramen is wanting, and the young crown rises within the pulp-cavity of the functional teetli, as in the Crocodili/i. In this genus, on the other liand. 216 it is deveioped outside of the pulp-cavity and fang of the old loot li, and takes its place, as in many Lacertilia and in the Tijllwnomorpha, by exciting the absorp- tion of the latter. The conic form of these fimgs in Saurocej)luilus is ap|iro- priate to such a succession, and their great length seems to preclude the nutrition of the young tooth from their bases. The use of the foramina on the inner face of the jaw is thus made apparent, viz, the nutrition of the successional teeth from without. I cannot trace the canal below the crown of the young tooth to the base of the pulp-cavity of the old tooth; and there are canals in the jaw below the latter, one of which probably carried the dental artery. Species of this genus are less abundant in the part of Kansas examined by me than those of the preceding genera. Two only have been observed up to the present time, as follows : . Saukocepiialus LANCiFORMis, Harlan, /. c. Medical aud Physical Researches, 362 ; Leldy, Tiausactiona of the American Philosophical Society, 185G, plate. — Saurodoii lanci/ormis, Hays, Transactions of the American Philosophical Society, 1830, 47C. Established on a right superior maxillary bone, from a locality near the Missouri River. It differs Irom that of the other species in having a very elongate superior suture with the premaxillary bone, and in the very short dental crowns, which are as wide as deep. The largest species ; known from the jaw only. Saurocephalus arapaiiovius, Cope. Established on a portion of a maxillary bone with a part of a suture, per- haps for attachment to a supernumerary maxillary. The size of the species is nearly that of S. lanci/ormis, and the crowns of the teeth are rather short, as in that species, and less elongate than in D. 2'hleboio?iius. The teeth are very closely set, and the fangs are separated by very narrow septa. The crowns are expanded so that the edges overlap in some cases. The form of these is much compressed ; width about equal to height ; the edges convex and acute. The enamel is smooth and without facets. The I'oots are without the facets shown by Leidy to exist in S. lanciformis, and appear to be longer than in that species, exceeding the length of the crown nearly four times. None are, however, perfectly enough exposed for complete measurement. As usual, there is a large foramen opposite each fang, below the inner alveolar 217 margin; ami, between the latter and the scries ol' ioramina, the surface is slightly cpuvex and minutely rugose. Measurements. M |)i'|illi oCllir 1)1111(1 0. Olir) Thickiioss iit Mill niHiwr'fiiiiul O.OOOri Total Iciisth of ;i tooth (f) • ". 0"-i Length of a crown 0. 004;j Wi'Uliofacrowii .■ 0.0030 Number of tooth in ono inch, 8. The size of this fish was probably about equal to that of the Ichtlujodcctes anaides above described. The type-specimen was found loose on a bluff of blue shaly limegtonc, fifteen miles south of Fort Wallace. Kansas. ERISICHTHE, Cope. Proceedings of tho Academy of Philadelphia, 1W2, p. 260. In this genus, the teeth are implanted in deep sockets as in other Sauro- dontidce, and the subalveolar line of foramina seen in Saurocephalus is wanting. The crowns of the teeth are compressed and knife-like, as in Daptinus; l)ut those of the anterior parts of the dentary and maxillary Iiones are greatly enlarged. Maxillary bone short, and rapidly tapering to a narrow edentulous extremity. Greater part of the dentary with a rugose band on the inner side of the teeth ; its distal portion with a row of small compressed teeth, separating the large teeth into two areas. While this genus agrees with Portheus and Ichthijodectes in the absence of nutritious dental foramina on the inner face of the dentary bone, and especially with Portheus in the irregular sizes of the teeth, the crowns are compressed and knife-like, and closely similar to those of Saurocephalus. But the form of the maxillary is so different from anything known among Saurodonlidce as to render it probable that the genus pertains to another family-division. The Portheus angulatus. Cope, from North Carolina, perhaps belongs to the genus Erisichthe, differing from E. nitida in its greater size and less degree of compression of the crowns of the large fangs. EuiSICHTHK NITIDA, Cope. Represented l)y numerous portions of a cranium with a fragment of a pectoral ray, discovered l)y Prof B. F. Mudgc near the .SoIoukmi River, 28 c 318 Kansas. Tlic, ray \s of (he compound character already described as belong- ing to otlier genera of this family ; its edge is not preserved. The maxillary hones are subtriangular in form, and support three or four large lancet-shaped teeth at the middle of their length. There are no teeth beyond them ; but, on the deeper side, there are several small lancet-shaped teeth. The outer alveolar edge Is rugose. The teeth are very flat, acute, and perfectly smooth. The teeth on the greater part of the dentary are interme- diate in size between the large and small ones of the maxillaries ; they stand on the outer edge of a broad horizontal alveolar plane. There are three large teeth in a series at the end of the dentary on the outer side ; they have been lost, but their bases are broader ovals than those of the maxillary bone. On the middle line of this part of the dentary is a close series of small com- pressed teeth with striate enamel, standing on a ridge of the bone ; they leave the last large tooth to the outer side, while on the inner side stand two or three lancet-shaped tusks of a short row farther back. Posterior deutaries 0'"'".10 apart. Measurements. M. Lougth of tlio maxillary boue above 0.088 Depth proxlmally 0. 030 LougtU of the crowu of a large tooth 0.0150 Width of the crowu at the base 0. 00G5 Lcugth of the hyomaiulibular 0. 1000 In size this fish exceeded all of the SaurodontidcB excepting the large species of Portheus. Niobrara epoch of Phillips County, Kansas. Discovered by Prof B. F. Mudge. STRATODONTIDJE. In this group, I have arranged several genera, which resemble Enchodus, the longest known of its forms. They are physostomous fishes, as indicated by the relations of bones of the superior arch of the mouth, the absence of spinous dorsal radii, the cycloid scales, and the general relationship to Esox. Agassiz and others have regarded some of them as allied to Sphj/rcena. This opinion was probably derived from a consideration of the forms of the teeth, which, to some degree, resemble those of Sphyrcenidm and Trkhiuridce. This is, however, like many other minor characters, one of those which appear in both of the great groups of osseous fishes. In all of the genera, the maxillary l)one is well developed, and supports 210 tcetli ; Viiit the extent to wliich it enters into the superior arcade of the nioutli varies. It is shortest in Enipo, and longest in Pachyrhizodtts. The pnMnaxillary is greally extended in E/njm, and shortest in Tethcoflus and Sfraloflus. The teeth differ from those of th(! Smirodojifirla- in their nuxh; of attachment; instead of being inserted by long roots into (Icc]) alveoli, they are anchylosed by the base to the alvcobar border of tlie jaw, vvhieli may sometimes be elevated on the outer side so as to give the roots a pleurodont attachment. This is the case in the genus Pachi/rhizodus. Although a large amount of material representing the forms referred to this family has come under my observation, I have in no case seen any remains of si)inous fin-rays ; in the pectoral fins in place, in two specimens of Empo, spines are wanting. The vertebral column is only known in Empo, where the caudal fin embraces three and possibly four centra, being thus a little more heterocer- cal than Salmo. The genera are readily distinguished by the following, among other characters : I. Premaxillary bone with several rows of teeth : Palatine teeth numerous, large ; all with pulp-cavity. . . . Stratodus. II. Premaxillary with two rows of teeth : Maxillary bone short; dentary with equal large inner teeth and outer rows en brosse Empo. Maxillary bone very long; one row of equal dentaries. . . Pachi/rhizodus. III. Premaxillary with one or no row of teeth : A large premaxillary fang ; anterior maxillary and den- tary teeth enlarged ; cutting-edges not opposite ; unsymmetrical Enchodus. Premaxillary toothless ; anterior maxillary and dentary enlarged ' Tctheodus. Large anterior tooth with a cutting-edge in front and a shorter one opposite and posterior F/umganodus. Owing to the fragility of many of the bones of the cranium, their char- acters remain unknown. It is, however, certain that none of the above- named genera present the prefronto-palatine articulation seen in the Sauro- dontidce. For a similar reason, the structure of some of the tins remains unknown. In some of the genera, the body is protected by scuta as well as by scales. 220 PACHYRHIZODUS, Agassiz. The genus as seen in our fossils is defined as follows : Muzzle flat; pre- niaxillaiy bones rather long, with two larger teeth together near the anterior end behind the usual external series; maxillary and mandibles with single series of simply cylindric subequal curved teeth ; mandibular rami closely articulated by a ligament. The teeth possess short stout fangs, occupying alveoli, of which the inner side and part of the anterior and posterior walls are incomplete. The teeth are, in fact, more or less pleurodont, but the extremity of the root is received into the conic fundus of the alveolus. They boar a superficial resemblance to those of a mosasauroid genus. Their mode of succession appears to be as follows: The crown of the young tooth was developed in a capsule at the base of the crown, or on the inner side of the apex of the thick root. The absorption which followed excavated both the former and the latter ; but the crown was evidently first shed. Finally, the old root disappeared, and the new one occupied the alveolus, leaving a free separation all round. Finally, on the accomplishment of the full growth of the root, it became anchylosed to the alveolus all round. The pleurodont position of the tooth facilitated the shedding of the root very materially. The premaxillary bones are well developed, but the maxillaries are more so, and enter largely into the composition of the border of the mouth. There is a well-developed angle of the mandible, but no coronoid bone. Well-preserved fragments of a large specimen of P. latimentum include a number of bones whose relations are not readily determined. A subrhom- bic element, with a sutural edge turned ? upward, and the fupper surface sculptured with ridges, has a small patch of teeth en brosse on the 1 lower face. An elongate bone, with gently concave longer sides and crenate edges, is very dense; perhaps a preorbifal. A large flat parallelogrammic bone, with a narrow articular surface at both ends, the one shorter than the other, with thin lateral borders, is possibly interopercular. The hyomandibular has its pterygoid articular border forming an obtuse angle with that for the inferior quadrate, and the latter a right angle with the line of junction with the oper- culum. Between the latter is a concave l)order marking half a circle. If the relations of this piece be jnoperly determined, there is no peduncle for the operculum. 220 A More complete speciiiicns ol' species of tliis genus sliow that vertebrae of the type which 1 have described (p. 240) unth-r the name of Anogmius belong to them.* The latter name may be used for this genus should it be ascertained that our species cannot be included in the one typified by the European Paclnjrhi:odi(s hamlis, Dixon. The posterior half or more of the cranium of a species allied to the P. lathnentuiu is preserved, witli both the ma.xillary l)one and teeth, and the basioccij)ilal element separated from its connections, adherent. Al)ove, the latter exhil)its two subtriaiigular articular faces in clo.se contact, for the e.xoc- cipitals. Below, there is a strong median carina, or crest, which is strongly grooved on the free margin; this groove probably represents the muscular tul)e. The exoccipital facets stand on a horizontal triangular face; l)ul, in front of this, the sides of the bone are beveled to the jdane of the base, l()r sutural adaptation to the prootic, etc. The structure of the superior walls of the skull may be largely discerned in this specimen. The cranium is flat and wide, and pressure has probalily somewhat increased the effect in this instance. Exoccipital, supraoccipital, epiotic, pterotic, parietal, and frontal bones are clearly distinguishable; l)ut there are points at which the sutures are obscure. The i)est defined are the epiotics, which are subtriangular bones, presenting the apex inward, and bearing a small round facet for the supratemporal on the posterior angle. The pterotics and postfroutals may be easily distinguished from adjoining bones, but not so well from each other. They have a thin outer margin, and their upper surface is marked by bands of irregular small fossa?, and an obtuse, longitudinal ridge. The middle line of tlie skull is occupied i}y the supraoccipital. Its proximal portion probal)ly separates the e.xoccij)itals, but this is not certain. It extends well forward, and the line of separation from the frontal is not well defined. Its anterior part has a massive trans- verse elevation, which sends a short median process backward, producing a T-shaped l)ody; the frontal suture is proljably in front of this. The supra- occipital is contracted beiiind this body, and its postero-exterior suture pre- sents a remarkable peculiarity in u straight and wide truncate articular face. This is opposed l)y a corresponding face of the parietal bone; the latter is of an irregular t()rm, and carries on its outer portion next the pterotic • As suggested Proceed. Amer. Philos. Soc., 1872, p. 355. 220 B • a stout protuberance. This is at the inner end of a strong ridge, which dis- appears near the outer edge of the pterotic. The protuberance looks as though adapted for an articulation. The frontals send a process backward, between the " supraoccipital " and the pterotic or postfrontal, to the base of tlic tuberosity of the parietid. The suture between the exoccipital and pari- etal is not clear. A suture is distinct enough, bounding the latter behind, but whether an expansion of the supraoccipital intervenes or not is not certain. The exoccipitals appear to be flat and quadrant-shaped, having convex antero-lateral borders. Each bears a strong condyle. An isolated bone has the appearance of an ethmoid, or more probably a vomer. It is cross-shaped, with the entering angles roofed by the contin- uous margins, nearly flat on one side, and convex and rough on the otlier C? superior) side. There are two parallel fossse on the under side of the subconic apex, and four just behind the cross-arms (two external large, and two median small). Tiiere are no teeth. The structure of the skull in this genus greatly elucidates that of the Saurodonthlm, the cranium of an unknown species of which is figured on Plate XLVII, figs. 7-8. It seems to possess the same composition poste- riorly, but to be so extended horizontally as to render the identification of the component parts much more easy. From a comparison of the two, it appears that the bone supporting the crest on each side of the middle line is the parietal, and as such bears an articular fticet lor the supratemporal. That bearing the inferior facet of the same, becomes the epiotic. The T-shaped bone of rachyrhizodus {Anogmius) is homologous with the ante- rior basis of the median crest of the Saurodonlidce, which exhibits a section of this form ; and we may suppose that this element in Pachyrhizodus does not belong to the frontal bone, but to the supraoccipital. The rootless teeth, and, perhaps, the exoccipital condyles, separate this Ibrm as a distinct family from the Saurodontidfe, while the exoccipital con- dyles, and parieto-'foccipital articular facets, are not found in Eiic/iodu.s and its allies. This genus was of less rapacious habits than the Sanrodontidie, and is of less powerful construction. It was probably a bottom fish, with habits s(nnething like those of Ba/rdcJitui, to which the known parts, especially the teeth, bear some reseuddancc. 221 Tliis genus was ostal)lisl)e(l by Professor Agassiz on a jaw-fragment from Sussex, England, willi a l)ricf" description. The Kansas remains resemble this fragment in their corresponding parts, and I refer them to the same genus for the jiresent. The genus Cono.saurus, Gibbcs, from South Carolina, is perhaps allied to this one. Its dentition is fully described by Leidy, who clianges the name to Cotiosaurops, mainly on account of the inappropriateness of the Greek Gavpo? to a fish. Tiiis word was, however, employed by the ancients to designate a fK--h; and the only use made of the word, out of composition, by modern zoologists, is for species of that class, so that it does not seem im- proper to use it here. Three, perhaps four, species left their remains in the strata examined by the ex[)edition. Paciiyriiizodus CAMiNTR, Cope. Established on portions of perhaps two individuals, which embrace one nearly complete maxillary bone; two premaxillaries of opposite sides; two nearly perfect rami of the mandible, with numerous other jjortions in a frag- mentary condition. These indicate a cranium of about a foot in length by six and a half inches in width, oval in outline, with moderately obtuse muzzle. The mandibular teeth are directed somewhat outward. The premaxillary is horizontal in front, and the maxillary narrow. From these fiicts, I derive, that the head was ))robably depressed, as in the modern Sauri, and very different from the prevalent compressed form of the Porthei and allies. The jiremaxillanj is several times longer than wide ; posteriorly, it is a subvertical plate ; anteriorly, it terminates a narrow obtuse portion. Just behind this portion, it is enlarged on the inner side, forming a knob whose upper surface supports the articulation with the ethmoid. It supports the two large teeth ijelow on a comnwn elevation of the jaw. The outer margin of the bone supports ten subcqual teeth, which are one-third smaller than the posterior pair. The outer alveolar ridge is a little more elevated than the inner, though a little less so than on otlnn- bones which support teeth. The external fiice of the i)one is nearly smooth, and the inner unites with the maxillary by striate squamo.*;al suture. 222 The maxillary preserved is nearly i)cricct, aiul may belong to another animal ; its depth coincides with that of tiic prcmaxillary. It is quite elon- gate ; about nine times as long as deep ; perhaps a little more. It supports forty-two closely-packed teeth, not all in functional service fit once. The distal end is contracted and grooved, and ridged on the inner face, as though for union with a supernumerary bone. The external face is longitudinally striate on the posterior half; the striae running out to the margins, forming sharp rugosities on the alveolar border. The superior (? palatine) articular surface is more than one-fourth the total length from the anterior extremity ; it is narrow, and somewhat lens-shaped. Both behind and in front of it, strong striae run from the outer to the inner side of the superior margin sub- longitudinally. Posterior to the superior articular surface on the outer face is a swelling like a muscular impression, from which grooves and keel extend posteriorly. The bone is concave on the outer face in front, to accommodate the OS premnxillarc. The mandibular rami are al)ruptly incurved at the symphysis, which is not serrate, and is subround, with an emargination entering from the inner infe- rior side. The dentary bone is much narrowed behind. The angular hone extends anteriorly on the inner face to the end of the posterior two-fifths of the dental line. The ramus is not very deep at the coronoid region. The articular cotylus is composed more largely of the angular than the articular. Its long diameter extends inward and backward, and is strongly convex ; in the transverse direction, slightly concave. Below and in front of it, the lower margin of the jaw is acute. The angle is oval and rather small ; it is promi- nent on the middle line on the inner side ; the edges are thin, the upper curved outward, concealing part of the cotylus. There are twenty-nine teeth on the dentary, whose sizes diminish toward its extremities. Their roots are very large and longitudinally striate and porous. Opposite the interval between the first two teeth, there is a tooth exterior to the general row, and another on its inner side. They are not enlarged. No teeth arc preserved except on the maxillary. These arc not very elongate cones, with round section, and well curved inward. Dense external layer entirely smooth. This species differs from the type P. hasalis, Dixon, in that the radical portion of the tooth is less swollen and more conic, and does not project above the exterior alveolar wall, as in that fish. 223 Measurements. M. Total length of tlio inandibiilar ramns 0.867 Total loiiBtli of tho tootli-lino 0.170 Transverse diaiiicter of the symphysiB 0. OIH Transverse diaiiietur of tlic base of a tooth 0.004 Length of the preniaxillary 0. OCH Length of the preniaxillary to tho large tooth 0.010 Greatest depth of the preniaxillary 0. Ol'.l Diameter of tho Large tootli at the base 0.007 Length of the maxillary to the ilr.st tooth 0. 171 Depth of the maxillary at the (list tooth 0.019 Depth of the maxillary at the la-st tooth 0.014 Depth at the artieiilar ^urface 0.0245 Found hy tlic writer near Fossil Spring, near Fort Wallace, in Western Kansas. Pachyrhizodus KiNGii, Cope. KstaUlislieil on tlio proximtil portion of a maxillary I)oiie with tlie articular surtiicc and bases of twelve teeth. It is a species of nearly the same size as the last; l)ut the hone contracts more rapidly than in that one, and presents a stronger interior longiliidinal ridge. The superior articular face is smaller and narrower, being subeiescentic, while the insertion-likt- tuberosity is nearer, and on the inner edge of the outer face, and connected with the articular face by a ridge, and not separated by a groove, as in P caninus. The outer face is depressed below the articular face much more than in that species, so that its lower portion becomes more convex. The roots of the teeth are of the same length as in P. caninus, and, as they are more numerous, they are more closely packed and more cylindric. Their pleurodont character is also more strongly marked. The superior surface of the bone is striate-groovetl longi- tudinally, not transversely nor obliquely. Total depth of bone ;it superior articular face, 0"'.022 ; depth at tenth tooth, O^.Ol 55. This species was found near the preceding. It is dedicated to I>r. William Howard King, post-surgeon at Fort Wallace, to whom, and not less to his excellent wife, I am indebted for hospitality and other assistance of a kind essential to the success of my explorations in Western Kansas. Pachyrhizodus latimentum, Cope. Represented by both mandibular rami and numerous lateral cranial bones of a specimen from the Solomon River, and a portion of a mandible from tiie Smoky Hill, Kansas. Tiie rami are relatively deeper than those of /■*. caninus; 224 and the shallow wide symphyseal surface is divided by a deep groove from the outer side, into which opens the mental foramen. Tlierc are two external planes of the dentary : the superioi-, or narrower, supporting the teeth, is bounded by a shallow groove below; the inferior and deeper plane terminates in a free, thin edge, excepting near the symphysis, where it is a little thickened, and stands at an angle of 45° with the symphyseal surface. The dentary is deeply doubly emarginate posteriorly, to receive the large angular ; the upper emargination is in the superior plane, the inferior in the inferior, and the ramus is deepest at the fundus of the notcii. From the two posterior ajnces, the ramus contracts gradually, the inferior border to the end of the long oval angle, the superior outline abruptly to the cotylus. The upper plane behind the upper emargination is occupied by a large longitudi- nally-oval fossa. A dentary, from which about an inch has been broken from the posterior upper end, supports thirty teeth, with one on the symphysis within the anterior one. From their reduced size, I suspect that the posterior teeth of the specimen were not followed by others. The crowns are conic, without cutting-edges, with smooth enamel, and strongly incurved. Measurements of No. 1. M. Longtli of tlio niau(lil)nlar ramus 0.305 Deptb of tho mandibular ramus at tlio last tooth 0. 060 Dcptli at tbo corouoid angle 0. OC) Depth at the cotylus 0.019 Width of the syuiphysis .' 0.022 Length of the crown of a tooth 0.009 Length of tho root of a tooth 0.010 Length of the hyomandibular bone 0. 074 This species is about the same size as the P. caninus. The coronoid angle of the mandible is elevated above the cotylus 45™" ; in P. caninus, of the same size, 25°"°. In the second specimen, the general form apjjears to have been deeper tliaii in the P. caninus, while the size of the teeth is similar. The external face of the bone near the alveolar border is convex, and not particularly rugose. The external alveolar wall is well elevated above the inner. IJelow the latter, the dentary bone exhibits a strong longitudinal ridge. The extremity of the dentary takes u wider curve from the symphysis than in P. caninus, giving a broader chin (whence the name) and muzzle. The symphyseal surface is smooth, transverse trilobate; the two outer lobes being separated by an emargination in the position of the foramen mentale. This 225 form is very ilHrcrent from that in P. caninus, where the symphyscal surface is subround. The anterior teeth are smaller than the median, and have the inner alveolar wall nearly as much elevated as the external. Tiie crowns are scarcely distinguishal)le from those of the P. caninus^ being curved-conic, with round section and smooth cementum. They form an incurved row next the symphysis, and a single tooth stands within the anterior one. Number of teeth in an inch at middle of ramus, 4.5. Paciiyruizodus sheareri, Cope. Associated with the bones of the P. caninus is a slender bone of oval section, which is marked on one edge by twenty-two transverse alveoli, whose outer margins are a little higher than the inner. No teeth preserved. It may belong to a fish of this genus, and is probably a superior maxillary bone. Consistently with this position, its outer extremity is more compressed than the proximal; the thickening being especially seen in the superior margin. A shallow concavity passes obliquely across this border from within outward and distally, as in P. caninus; but the articular face is not ])reserved. There is a longitudinal angle on the external face; and the superficial layer of bone is nowhere grooved or rugose. The pleurodont character of the tooth- attachment is more marked proxiraally. Length of piece, 0'".041 ; vertical diameter, 0'".007 ; greatest transverse diameter, O^.OOSS. This species is dedicated to Doctor Shearer, assistant post-surgeon, to whose interest in the subject the geology of Kansas is indebted to many useful discoveries. Pachyriiizodus leptopsis, Cope. Represented by portions of the right and left denlary Ijoucs, with other jinrlions of the cranium. The symphyseal part of the ramus is not incurved as in /-'. caninus and P. kingii, but is obliquely truncate, indicating that the chin had a compressed lljrm, and was not rounded, as in tiicui. The lower portion of tlu! l)one is thin and laminiform, to a deep groove, which extends from the edge of the syniphyseal face, along the inner side, at one-third the depth of the ramus from the inner bases of the roots of the teeth. The latter are thus supported on a thickened basis. They are ratlier roinote in a functional condition; each interspace being entirely occupied by the alveolar fossa of the shed tooth. These bases are very stout, and composed of dense 29 c 226 bone; their apices rise a little above the edge of the external alveolar border. The bases of the crowns are oval, and they display an anterior cutting-edge, whicii descends from the apex, thus differing materially from those of the P. cnn'mus. The teeth diminish in size from the middle of the dentary bone to the symphysis ; besides the latter are two teeth of reduced size. The outer face of the dentiiry is smooth, except some small impressed fossa?. Tiie mental foramina are small, and do not issue in a groove. Below them, on the outer face, is a fossa, with level floor to the inferior margin. Measurements. M. Length of tbo niargiu beariug four teetli 0. 050 Depth of the ramus at the third tooth 0. 025 Elevation of the tooth-basis 0.008 Long diameter of the base of the crown on the same 0. OOG STRATODUS, Cope. This genus is well characterized by its dentition, which is remarkable for the small size and large number of the teeth, and their peculiar form. I possess one premaxillary, a considerable part of the maxillary, and nearly the whole of both palatines, besides other bones, of one species. I have, unfor- tunately, no dentary bone of Stratodus. The outer row of palatines resem- bles, in some measure, those- figured in Cimolichthys levesiensis, Leidy, by Agassiz. The premaxillary teeth are in two series. They are stout at the base and oval in section, and are contracted and flattened rapidly upward. On this basis is set an oval, sharp-edged, flat, or spade-shaped crown; the long axis of compression being placed at right angles to that of the compression of the apex of the base. This gives a barbed appearance. The maxillary teeth are similar in form, but are in l)ut few rows. The imlatine teeth are constructed on the same plan, but they are longer, and the bases are subcylindric and slightly curved. All the teeth possess a large pulp-cavity. The irremaxillary hone displays some of the density of composition seen in Enchodus. Its upjier anterior surface meets the inferior at an acute angle It is a I)road oval, and is slightly concave. The inner face forms a truncate rim round the bases of the inner teeth, and terminates in a vertical crest of dense bone. The external face is, on the other hand, perpendicular, and extends obliquely upward and backward. An acute anterior angle of the maxillary underrnns it below, so far as to exclude all but one or two of the 227 prcmaxillar}' toctli from tlic outer row. The external lamina of the premax- illary forms an extensive squamosal suture with this part of the maxillary by overlapping it from above. This arrangement shows a certain similarity to Esox, especially in the large number of palatine and small number of max- illary teeth. It (lillcrs materially in the lack of articular surfaces between the maxillary, palatine, etc., in the upward prolongation of the prcmaxillary, and the peculiar forms of the teeth. Stkatodus apicalis, Cope. Established on one incomplete individual, as above mentioned. The maxillary teeth are mostly smaller than the premaxillaries, and diminish in size posteriorly ; there are four or five series of them anteriorly ; seven to nine rows on the palatine bones; they are slender, and curved down- ward from oblicpic bases, and cylindric in section ; they contract to a neck, and then expand into the ovate spade-shaped cutting apex. They are in every respect the largest of the teeth, some reaching a half-incli in length. Those on Ihc inferior or outer margin are most slender; those of the inner stouter and more conic. All the spade-like apices are black in the specimen, while the shanks are i)ale, except the premaxillaries. The palatine bones are flat- tened in one plane, and contracted at both ends. At the anterior, there is an external concavity, perhaps Ibr niaxillary or prcmaxillary. A ridge divides the upper surface lengthwise ; the outer edge is thinned posteriorly, and there are three long grooves which extend to the posterior extremity, probably for sutural union with the pterygoid. The premuzillary bears a slight resem- blance to the mandibular bone of a chimeroid turned upside down. Measurements. u. Length of a portion of .in os palatinmn i^-_z-- ^- ^^ Length of same restorcii 0. 148 Greatest %vi(lth 0.020 Greatest thickness on tlie margin 0. 003 Longth of the premaxiHary (fr.agment) 0.013 Length of the prcinaxiUary, inner side 0. 025 Length of the prcmaxilhiry, outer sido to the maxillary 0. 012 Width of the prcmaxillary in front above 0. 010 Length of a preniaxillary tooth 0.005 This fish was considerably larger than Esox reticulatus or E. Indus. In the lack of mandible, its habits cannot be fully inferred; but the armature of the superior bones of the mouth is less powerful, relatively, than in those fishes. Found l)v nivsclf in the blue limestone near Fort Wallace. 228 EMPO, Cope. Tliis genus is represented l)j very numerous remains in the chalk of Kansas, and a consideral)lc amount of material pertaining to it has come under my observation. The best-preserved remains are vertebrae and the jaws ; all other portions of the skeleton are so fragile as to be difficult of extraction from the matrix, but a few specimens preserved by the care of Professor Mudge, of Kansas, have thrown especial light on these little-known parts of the structure. The premaxillary bones arc longer than in any other genus here described, and terminate anteriorly in a compressed-conic ape^ of dense bone. Medially, they have greater transverse thickness and a semicircular section ; while, dis- tally, they are compressed, and extended vertically. There is an unsymmctrical crest on the superior border, the only point of contact with the ethmoid. The maxillary is continuous from this point, and is usually attached by the coossi- iication of a squamosal suture. It is vertical and Hat, and probably of no great extent. The extremity is broken off in the specimens. While the pre- maxillary supports two scries of teeth, the maxillary presents but one. The dentaries support several series of teeth ; one of large ones on the inner side, and several smaller on the outer. The small ones are double- edged, and diminish in size to the external margin ; the imier ones are like the large ones of the maxillary series, with a flattened cutting apex. A strik- ing character observed in two species of the genus {E. nepcsoUcn and E. semi- anceps) is the absence of any angular process of the mandible ; the narrow angular bone being ti'uncate vertically from the transverse cotylus. There are other tooth-bearing bones, which I cannot positively locate. Some of these are laminiform, and are covered on one edge, and for some dis- tance on the adjacent sides, with a dense brush of small acute conic teeth. Tnis bone is palatine or pterygoid. Another is a massive tongue-shaped bone with one narrowed extremity, and the other expanded into a lamina in the same plane. It supports a median series of teeth, mostly in two rows, whose crowns are curved and sin)ply conic. This bone is sometimes nearly symmet- rical, so as to resemble a vouier; but in others it is distinctly unsymmetrical. It is probably a superior or inferior pliaryngeal. In one specimen, it lies pressed down on the dmitary, with the leetli on the inferior side. Another bone is rod-like, with triangular section, with a single row of small conic teeth set on the edge, whose section gives an angle. 229 rpi lie (ci'lli (if llic larger class are without inil|)-cavity. The indication of (la- iiKulc ol" siicccs'Sion of the teeth is fmnished hy various specimens. The crown of the successional tooth appears in a small excavation on the inner side of the basis of the tooth. The absorption, commencing at this point, no doubt removes the basis, so that the crown falls away. A specimen of E. nepaolica exhiljits the cranium Irom the inner side. Till! frontals arc distinct; the pterygoids and cctopterygoids are displayed, with a series of teeth standing either on the anterior part of the latter or on the posterior part ol' the palatine bone. Posterior f)arts of crania of E. nepceolica and E. semianceps show that the muscular tube was not open, and probably did not exist ; although a shallow fossa in the base of the basioccip- ital marks its position. There is no articular surface on the side of the basi- occipital for the extremity of the lower limb of a post-tem])oral. The supra- occipital projects fitrward in a quadrate plate on the superi(»r cranial surtace, and sends out a high crest from its posterior flice, which bears a l();vsa on each side of the superior base of the crest. In a specimen of E. senuanceps, where the quadrate and adjacent bones are well preserved, I cannot discover any symplectic. The cervical vertebra; are separate, and not modified in structure. They present large fossae for jileurapophyses on the inferior face, except the first, which, in E. mpcuoUca and E. semianceps (sp. No. 2), present two sliort par- allel crests directed downward. The anterior dorsals are marked with narrow grooves and ridges laterally, which finally give place to a nearly smooth or only line-grooved lateral face on the greater part of the column. Posteriorly, deep lateral grooves appear, which extend to the end of the series. Except- ing a short distance anteriorly, the neural canal is bounded l)y a vertical lam- ina on each side; the neurapophysis rises from tin; centrum outside oi this, and, I'orniing a strong rih on the lamina, rises to unite with its liillow. A c(»r- res[)<)nding lamina hounds the ha^nal canal of tin; caudal vertebra, and the hiemapophysis appears as a ril) on its outer side, and then joins the correspond- ing one of the t)pposite side. There arc vcrtebnc included in the caudal fin. The ribs are well developed, and the abdominal cavity not elongate. Ventral fins are not visible in the abdominal position in the best-prcserv(!d specimen o\' E. ncptwlica. No strong fin-rays can be ccrtaiidy referred to liie genus. The pecloral liny aii^ atlaelied to the lower [>art of the clavicular arch. The body was covereil with very large scales on the side and on the miounded by vertical lamina3. The neural spines are expanded on the 'anterior base, as in many recent 231 fishes. The centra are grooved-striate, and wit hunt hirge Iongiluoth prcmaxillary and portions of the maxillary and dentary bones of one specimen represent tliis species. They show it to have been a powerful fish, of the size of the Encliodus petrosus below mentioned. The premaxillaries arc excavated by the usual three oblique fossae above on the inner side. The alve- olar face is a ridge extending oblirpiely across from a tuberosity on the inner side, behind the apical tuberosity. There is no surface for the attachment of a tooth, and no scar or other trace of the former existence of one. The maxillary underlaps it by an oblifjue suture, and supports a large tooth simi- lar to that at the end of the prcmaxillary in Enchodus, behind which are seen the crescentic scars of the previously shed teeth. The outer lace of the basal cementum of this tooth is perfectly smooth. The distal portion of the dentary hone is toothless ; its anterior tooth is a fang, with the base excavated in front ; and an angle rising from the external side of it becomes a latcro-exterior cutting-edge of the crown to the ape.x. The inner posterior, or more convex, face of the tooth is regularly and closely striate-grooved. On one dentary, there are three or four small denticles in front of it on the outer side. The smaller teeth have twtj cutting-edges, and tin; posterior liice at (he Ijase is grooved striate. This regular grooving, as well as the large size of the lirst maxillary, distinguishes this fish from the I'/iasganodus anceps. t ^ o Measiirements. ir. Leugth of the preiiiaxillary bono above 0. 0*5 Depth of till! preiiiaxillary bone above (1. 0;W Width of the basis at tlie lirst maxillary tooth 0.010 238 M. Depth of the dentary at the first tooth 0.080 Length of the dentary to the first tooth 0. 020 Length of the first tooth 0.032 Interval between the maxillary teeth 0.008 Niobrara epoch of Phillips County, Kansas; discovered by Prof. B. F. Mudge. ENCHODUS, Agassiz. 'o^ The massive premaxillary bones of this genus are well known. They support an elongate fang at tlie anterior extremity. The maxillaries underlap them, and support some elongate teeth near their anterior end. The anterior denlaries are also longer than the others. The teeth are all anchyloscd by expanded bases ; the posterior ones on an oblique alveolar surface. The long teeth are removed by an absorption set on foot at the posterior basis of each, which progresses until the crown readily breaks away. The successional teeth appear in front of the old ones, appearing successively as the aiiimal increases in size, so that the scars of those of preceding stages are only indi- cated by successive curved lines, becoming more prominent from the back to the front of the bone. _ The posterior part of the cranium of E. petrosus exhibits a supraoccip- ital crest with short basis ; tliis element separates lateral pieces, which are epiotic or |)arietal. They are separated by a concavity from the bone that occupies the external posterior angle, which is epi- or opisthotic. On the inferior view, no muscular tube appears, nor any otic foramen, such as exists in the Saurodontidcc. The visible surfaces of the exoccipital, the pterotic, the postfrontal and prootic, are subequal, and the alisphenoid is well devel- oped. A strong rounded ridge extends from the postfrontal angle to the anterior base of the prootic, which bounds a deep fossa which occupies the point of union of the postfrontal, pterotic, and prootic Cervical vertebras are not coossified nor modified in any especial manner. Their centra are rough- ened with raised inosculating ridges. This genus has long been known from the Cretaceous of Holland and England ; two or three species liave left their remains in the greensand of New Jersey, and others occur in the chalk of Kansas. Dr. Leidy described a species' from the Cretaceous formations of the Upper Missouri region, which he called E shumardii. Several premaxillaries of a rather larger species were ' Enchodua shumardii, Leidy, Proceedings of the Academy of Natural Sciences of Philadelphia, 1856, p. SI")?, i.s a smaller species than any of those here described. 239 oI;lained by my expedition ; I)ut the species is not determinable. The diam- eter of the basis of the tooth is 0"'.012. The long tooth of a species of medium size was detected, the Enchodus calliodon. Cope {Encliodus sp., Cope, Hayden's Survey of Wyoming, etc., p. 424), in the matrix beneath the verte- bra; of Elasmosaurus idatyurus. Enchodus tetrosus, Cope. Establislicd on numerous portions of cranium and vertebra; of one indi- vidual, which had grown to the size of a twenty-five-pouiid muskallongc. The upper surface of the cranium is smooth, excepting along the inner border of the pterotic, where a narrow ridge supports two rows of small enamel tubercles. Numerous similar tubercles ornament the external face of the postfrontal bone. The premaxillary has the anterior margin truncate obliquely upward and backward ; its lower margin passing into the base of the single large tooth. Alveolar surface elongate, posteriorly narrowed to an obtuse edge. The maxillary exhil}its both borders obliquely truncate, with sutural face ; the alveolar asjiect supports two teeth, one larger than the other. (No. 2.) The premaxillaries are very massive, and exhibit, on their upper faces, three oblique fossae ; the posterior transversely subdivided. External face smooth. Measurem&aU. M. Length (distal end lost) 0. 0C7 Greatest width of the alveolar face 0.018 Depth of the outer face 0.030 Diameter of the basis of tho tooth 0.009 Obtained l)y Professor Mudge from beds of the Niobrara epoch in Kansas. Enchodus dolichus, Cope. Represented by tiie premaxillary and adjacent parts of the maxillary bone with teeth, of a specimen of one-tenth the size of the preceding, and differing from it in the more slender proportions and the peculiar positions of the teeth. The premaxillary is long and narrow, and oval in section, supports one tooth (the large extremital one), and has two sublongitudinal fossa; on tlio inner side above. Behind these is a fossa divided by inosculating ridges, and 240 a similar one on the ontcr side of the middle keel, which overlaps the two posterior ones. The maxillary underlaps farther than in some species, bring- iuiT the anterior teeth half-way between the large prcmaxillary and large max- illary teeth. In E. i^etrosus they are much nearer the large maxillary. Measurements. M. Lcnstbof the prcmaxillary 0.0270 Distance bctweou the largo maxillary ami the prcmaxillary teeth 0. 0180 TratiRvurse diameter of the prcmaxillary 0.0070 Trausverso aiamcter of the large maxillary tooth 0. 002G The type-specimen of this species was originally described as pertaining to the genus Empo. Enchodus CALLiODON, Cope. The tootli on which this species rests is especially elegant. It is quite slender, and gradually contracts to the acute apex. The cutting-edges, which extend to the base, are on one side, and are separated in one direction by a narrow, slightly convex, and perfectly smooth face. The inner face is strongly convex, being more than half a circle from the middle of the length down- ward. This is also smooth on its anterior and posterior aspects ; but, on the inner, there arc nine sharp delicate keels, which disappear as the tooth con- tracts, the last terminating with the third quarter of the length. Total length, 0"'.02 ; longitudinal diameter at base, 0'".0025 ; transverse diameter at base, 0'".0035. The apex of the tooth is black. From near Fossil Spring, Western Kansas. ANOGMIUS, Cope. Proceedings of the Americau Philosophical Society, 1871, p. 170. This name was applied to a genus supposed to be allied to the Saurodon- tidce, and represented hy vertebra only. One species was named A. contractus, Cope, /. c, which was found by Professor Mudge. I have seen nothing resem- bling these vertcbnB among either of the three families above described, and cannot ascertain their exact affinities without further investigation. It is clear that they are not referable to the known genera of Saurodontidcc nor of Stra- lodmtidce. They present a marked character in the crowding-together of those caudal vertebraj which precede those that support the caudal fin. The centra are shoitened, and the prolonged neural and htemal arches and spines 241 lie one on the other, forming a tim-shaped body. The arches do not, at the same time, become anchylosed. This structure is seen in the A. contractus and in a second and smaller species. It finds a parallel in the caudal verte- bi-jE of the genus Ischyrhiza of Leidy, from the greensand of the New Jersey Cretaceous, where all the elements of this fan-shaped body, centra, spines, etc., are coossifi.ed into a solid mass. This will define a family, and a species having the same structure is common in the Miocene of Maryland. In Anogmius, the sides of the centra, though lacking the large grooves of other genera, are striate-grooved and reticulate. So are those of Ischyrhiza, and both in this resemble the recent genus Esox. Add to this the fact that the teeth oi Ischyrhiza are almost exactly like those of Esox, especially as to their large-fissured fangs, and half-pleurodont insertion, some relationship to the Esocidm may be predicated. I brought forward this suggestion as to the affinities of Ischyrhiza in the preliminary monograph of the fossil fishes of Kansas already quoted. Anog?nius contiactus was about the size of Ichthyodectes prognathus. The second Anogmius is not more than one-third the size ; the caudal vertebrae are more aggregated; and the neural spines, after leaning backward, are turned upward. The specimen came from Lower Butte Creek; no parts of cranium nor fins were found. The vertebrae originally described by me as pertaining to Ichtliyodectes ctenodon belong either here or to Ischyrhiza ; they agree with the latter in most respects, having the neurapophyses coossified with the cen- trum. Tiiey are several times larger than those of A. contractus, and relatively shorter, being about equal to those of Ischyrhiza mira, Leidy. I do not name these species, as they may belong to known genera, and will be, in any case, better identified from cranial and fin remains. APSOPELIX, Cope. Established on the remains of a fish preserved on a block of clay. It presents its ventral- aspect, and displays pectoral, ventral, and anal fins, with the series of interneural spines to which the dorsal radii were articu- lated. The scales are large and cycloid. They do not present a trace of radii, but are marked with fine and close concentric grooves. These assume a vertical direction on the exposed surface, and are there more irregular ; the 31 c 242 more marginal ones icrminating above and l)clo\v. But few, i. e., the ccnlral, grooves are truly circular. No abdominal carina. Tlic two pelvic bones are together truncate heart-shaped, the acuminate apex presented forward. Tlieir posterior portion is a strung transverse rib; anteriorly, each is a thin plate, with thickened outer edge, uuiling with its fellow on the median line. The median portion is so thin as to be readily broken away. The ventral fins are short and wide, with numerous rays. The coracoid bone is a broad lamina, and the pectoral fin evidently had the su])port of rod-like humeral bones of no great length, after the type of most physostomous fishes; but their form cannot be made out. Pectorals not elongate. The anal fin originates but a short distance behind the ventrals, and was not armed with an anterior spine; its length cannot be made out. Immediately above it, a dorsal fin, with slender rays, is represented by the bases of these rays. From above the ventrals to above the distal portion of Ihc pectorals, a line of projecting points appears in the specimen, which I am disposed to ascribe to the articular portions of the interneural spines and attached fin-rays of a first dorsal; but of this I cannot be entirely sure. The vertebrae are longer than deep, and present the two deep lateral grooves frequently seen. The number of the cervico-abdominal series is twenty-si.\. The ribs are delicate, and supernumerary ribs are present. In comparing this genus with forms already known, points of distinction from 0,11 of them may be detected. Thus, the lack of pectoral sjiine will distinguish it from the known genera of Saurodon/idcc at least. The character of the dorsal fin distinguishes it from Characinidcc, SalmonidcB, etc., which, with the scales, point toward Clupcidoi and Elojndce. From these, the form of the pelvic bones distinguishes it. The end of both muzzle and caudal region are destroyed. The latter evidently contracts from the anal fin, and was not probably very elongate, but more as in Elops or Sanrus. ApSOPELIX SATJRIFORMIS, Cope. Scales large; ten longitudinal series to be counted across the obliquely- depressed body. No lateral line visible. About seventeen transverse series between ])ectorals and ventrals. Ventral broad ; when laid backward nearly leaching anal, but far behind the pectoral. Anal probably rather short; but ' thirj is not entirely certain. Radii, D. ? — 12, P. 16, V. 12. 24B Measttrcmcnts. M. LeDglli from (lie basis of Pectoral ray No. I. to Ventral ray 12 0.083 Length I'roni the basis of P. I. to A. 1 0. 0985 Lenglli of the ventral fni 0.0173 Width of the ventral fin distally 0. Oi:5 Length of tho basis of D. 2 0. 01G8 Width of tho body 0.047 Width of tho pelvic bones together 0. OIC Length of tho pelvic bones together 0. Olfi The size of this species is about that of a one-pound brook-trout. From the bed No. 2 of tlic Cretaceous of Meek and Ilayden. Found in digging a well at Bunker Hill station on the Pacific Railroad of Kansas. SELACHIL Remains of sharks and ray.s arc fur less abundant in the Cretaceous of Western Kansas than in New Jersey, and are much exceeded in abundance by the physostonious Aciinopferl, as the present account indicates. In the region near Fort Hays and Salina, sharks' teeth are more frequently found. The ccstiacionts arc, on the other hand, more abundant, since five spe- cies of Pfi/chodus Ag. have been found in No. 3; in beds in various parts of Kansas and Colorado. GALEOCERDO, Miill., Henl. Galeocerdo crassidens, Cope. Establislied on two teeth of the type of G. aduncus, Agass., i. c, with one cutting-edge much more convex than the other. The processes of the fang are rather narrow ; that beneath the convex cutting-edge the most so. The apex of the tooth is very short, entirely plane, and stands over the middle or inner edge of the wider process of the fang. The shorter cutting-edge is straight or convex to near the base, where a short divergent heel develops itself The anterior edge is strongly convex, and all the edges arc denticu- late. One side is more convex than the other. No denticles. Cementum smool li. Measurements. M. Length of the basis ." 0.014 Ilciglit of the crown • 0. 01 Height of the root 0. OO") Width of tho tooth at tho contraction 0 0] 244 GaLEOCERDO IIARTWELLII, Cope. This species is of tlie G. egertonii group, i. e., with the cutting-edges subequal and symmetrical. The basis is broad, and with convexities of the fang, instead of the processes of the last species. The external parts of the cutting-edge rise gradually from the base, and then more steeply at an obtuse angle. They are convex on each side above, and meet symmet- rically, forming a little less than a right angle. No denticles. Cementum smooth. Edge everywhere denticulate. One side of crown plane; the other convex. Measurements. M. Lengtli of the basis 0.0215 Length of the fa.ug 0.0195 Elevatiou of the apes (from the concavity) 0. 0145 Width of the crown at the contraction .- 0. 012 This tooth is stouter and larger than that of G. egertonii, and was found beneath the bones of the Protostega gigas. It is named after Martin V. Hartwell, a member of my expedition, to whose acuteness and industry I owe many specimens. PTYCHODUS, Agass. Ptychodus janewayii, Cope. Established on teeth resembling the posterior or pavement teeth of Heterodonlus. Their arrangement cannot be described, as they are only known as separated specimens. Their surface is regularly convex, and covered with a dense layer, which does not exhibit pores, and is thrown into transverse or oblique ridges. No root is preserved in the specimens; but the basis is coarsely porous. A small tooth, probably lateral, is an oval, witli its surface thrown into four folds, which traverse it obliquely from border to border. At the base of the outer, at one end, is a series of adherent tubercles ; at the basis of that at the opposite end is a broken fold, with tubercles at its outer base. Length, 0°.0045 ; width, 0".002.5. A portion of a larger and more central tooth has the surface witli an unsymmetrical convexity, and crossed trans- versely by five folds from border to border. Discovered by Prof B. F. Mudge, near Stockton, Kans., in a bed con- taining many teeth of Oxyrhina, Lamna, etc., of small size. Dedicated to Dr. John H. Janeway, post-surgeon at Fort Hays, Kansas, who has rendered much important aid to paleontology and botany in Kansas. 244 A ACTINOCITTIM. This order is established for fislies from the Ui)per Cretaceous of Kan- sas and England, of wliirh nothing is certainly known excepting the scapular arch and pectoral tin. These are fully described under the head of tiif only family, the Pelccoplcridce, so that the characters distinguishing this fioni other orders oidy will be adverted to here. As iu no other order of actinopterous fishes, there arc six single and one paired basilar bones supporting the pectoral tin, and all articulating with the scapula. In yl^^/V/, there are nine such bones; but only one of them articulates with the scapula. In Batrachus, there are five, but four of wliicii articulate with the scapula, and the anterior one is single. In all other Actlnoplen, there are four, three, or two basilar bones, and the nntcricn- Elec- toral ray articulates inunediately with the scapula. The clavicle is osseous, and the coracoid, if rightly deterniiued, is short, and attached to the clavicle. Until other portions of the skeleton Ijeconie known, it will be inipossi- l)lc to assign its place to this order, but it lessens, by its fin structure, tlx^ interruption between Amia and other rhysostomu PELECOPTERID.E. A well-marked type of pectoral arch is iigurcd on Plates XLVIII, tigs. 1-2, and LIV, fig. 8. Like that of rorthcus, it supports a powerful spine, but of a very dilTerent character from that genus. These spines are very common in a fragmentary condition in the clay-chnlk of Kansas, and in three instances I have obtained them iu immedintc connection with the scapula. In one of these, the clavicles also are present. These are elongate and thin, the posterior edge laminiform, the anterior obtusely rounded. The bone is strongly curved antero-posteriorly, showing that the clavicles ami coracoids were projected forwards below. Both extremities are strongly marj^ed with grooves, the upper for sutural union with the posttemporal, and perhaps epiclavicle. One eiul is wider than the other, and its posterior edge is like a convex knife-blade. The scapula is quite massive; the general form of ils IkkIv being that of a very irregular three-sided pyramid (see fig. 9). its 244 B superior angular border sends ofT a lai-ge fau-sliaped osseous plate inward, upward, and forward. Its expanded distal end is doubtless in contact with the clavicle or epiclavicle ; it rises from the scapula without sutural interruption. A shorter, fan-shaped process rises from the lower posterior border of the scapula, and unites by its broad fextremity with the inner side of the clavicle, from which it is distinguished by a suture. It incloses a large foramen with the clavicle, and probably represents the coracoid, although I cannot detect any suture separating it from the scapula. It is much shorter than that of Portheus. The postero-external side of the scapula has three articular facets at the outer or thick extremity, from the base of which a wide, deep groove extends inwards to the apex of the bone. Two of the facets are on the jtlane Fig. 10. Fig. 10. — Left pectoral spine of Pelecopterus chininjits, oue-half natural size : a and b, the opposite .anteriox' basilars; c, crescontic cotyli for tlie posterior median basilars; d ef, three median basilars; nc, scapula ; co, coracoid. of the posterior face, one above and one below. The third is between and exterior to them, and stands on an elevated tuberosity. The three together support the pectoral spine. Their surfaces wei'e doubtless furnished with a thick cap of articular cartilage, as they are granular-rugose. Tlie groove above mentioned is divided into five or six transverse subcrescentic fossae, or cotyli, for the posterior basilar bones, whose fundus are also rugose. The entire pectoral fin, so far as it is known, is devoted to the construc- tion of a powerfid spine. This follows from llic fact Ihat the spine is sup- 244 C portcil \)\ all of the basilar Ijoiics. Six of" the latter articulate in the fossae of (he groove of the scapula already described. They are flat, contracted at tlic middle, and expanded at the extremities. In front of these are two others, of a short, thick, cylindric form, one applied to the superior, the other to the inferior fiicets of the scapula above mentioned, while tlie tuberosity rises pedestal-like between them. This structure gives a slight hinge-movement, like the opening of the blades of a knife, and entirely unlike the rotary hinge- movement characteristic of the Siluridfe. The spine is composed of parallel rods in close apposition. The ante- rior edge being oblique, the extremities of the rods terminate successively al tlie border, which is trenchant, constituting the ofTensive part of the spine. The edge is hardened and the adjacent parts of the spine thickened, and in some cases roughened by a deposit of a hard substance resembling enamel. It is either straight, or regularly undulate or serrate, with recurved, acute, tooth-like processes. The smaller species exhibit the serrate character ; the larger, the regular border. In either case, a most formidable weapon is indi- cated, not less admirable than those already described from Paleozoic rocks. There is a considerable resemblance between the serrate type and the spines of the Carboniferous genus Edestus, where the teeth are more developed and denticulate. Spines of this type were referred by Professor Agassiz to tiie cestra- ciont sharks of the genus Ftychodus ; but the structure of the scapular arcii, now first described, demonstrates the incorrectness of this association. The increased number of the basilar bones shows clearly that they belong to a peculiar family, which I call the Pdecopteridce. The principal genus receives the name Pclccoiiterus, leaving the question of its relationship to ErisiclUlie an open one. The supposition that these spines belong to Portheus and its allies is, therefore, no longer entertained. PELECOPTERUS, Cope. The characters of this genus are only known from the bones of the scapular arch and the spine of tlie pectoral fin. As these have been already described under the head of the liunily, it remains to discriminate the species. Three of these have come under my observation, which are fishes of large size. They may be readily distinguished by the character of the cutting- edge and the relative size and direction oi'tlic coniponeni rods. 2U D Smaller: rods larger and less oblique; edge undulate and serrate P. jwnikiosus. Larger: rods smaller and more oblique; edge entire or irregular 1\ gladius. Pklecopteeus peeniciosus, Cope. Although the pectoral spines of this fish are abundant, they are rarely obtained unbroken; and I had long been fliniiliar with their basal and distal ])ortions before I was aware that they bore that relation to each other. The finest example was obtained by my friend Professor Merrill, on Spring Creek, in Rooks County. It includes spines and clavicles of both sides, with scapular and basilar l)ones of one side. Neither spine is complete, but the longest measures twenty -eight inches in length. The component rods make a small angle with the cutting-edge, and, commencing narrow at the base, widen out at the middle, and retain their widtli to the end at the cutting- border. The rods at the back of the spine are narrower than those at the middle and edge. The section is narrow, especially at the back, and it is thickest a little within the edge. There are thirty-four rods at the l)asc, au;ila, liody only 0. 0(i."> Wiiltli of the fan-process at the cxtronnty 0. 0(!r> Width of tlie shaft of the fim-proccss (depressed) 0. 0-J5 Length of the spine (apex wanting) 0.7(15 Width at the haso 0. 0C>7 Width at the middle 0. 04H Thickness at the middle 0. OOri III ;i sct'diid specimen (Plate XLYIII, fig. 2), the coracoid ])rocess is pn'seiil, sliowiiig ideniity of character witli tlic scapulii of" tlie I\ chirurgiis. 'i'his specimen also presents the anterior scapular hook. The dentation of the cutting-margin appears nearer the hase in this than the preceding specimen. In a third, which includes only the distal part of the spine (Plate LIT, tig. 2), there are twenty teeth in 0"\235. From Prof 11 F. j\Iudge's collection. Pklecopteru.s chirur^us, Cope. Represented by the basal part of a large spine attached to the scapula (Plate XLVIII, fig. 1), and by an isolated scapula (Plate LIV, fig. 8). These bones are more massive than those of the last species, A\hich they resemble in various points. The most prominent of these is the wider and less oblicpie component rods than in F. gladius. The basal three inches of the anterior edge only is preserved, and this shows no trace of the undulation of that of the P. jjerniciosus. ■ The enamel-deposit covers a width of three rods. The scapula is, in this instance, attached to the clavicle, to a ledge on the inner posterior face of the latter, which joins the upper edge of the outer side or base of the former. This jiuictioii being rather narrow, it is strengthened by the solidly-coossificd coracoid on tlie inner side of it. The rspinc contains fifteen rods in a width of 0™.051. Measurements. M. Vertical wiiUh of the scapular hody in I'miit 0. (i| I Width of the chiviclo at the scapula O.irx, Length of tlie coracoid inside ('.041 This, as well as the second specimen, was ll'uiul by Prof B. F. Mudge. Pklecopterus cladus, Cope. Distinguished from the preceding species l)y the superior size and mass 244 P of its spine, the small aiul more oblique rods, and iKJii-dciilale edge of tlie same. It was originally established on a spine which, when complete, measured, according to Professor Mudge, forty-one inches in length ; the portion now before me measures thirty-one inches. The margin is exceedingly acute, and is coated with an enamel-like iayei-, which conceals the extremities of the rods of which the spine is composed. Near the middle of its length, these rods number thirty; but whether the entire width of the spine is preserved is uncertain. The transverse section is a crescent fiom the base to beyond the middle; the surface being thus somewhat trough-like. The spine has been somewhat distorted by pressure; l)nt I cannot discover that the form in question is entirely due to that cause. The edge is excavated and notched at irregular points, indicating the frequent use to which this forinidaI)lc weapon was put during the life of its possessor (Plate LII, fig. 3). 3Ieasiirements. 11. Tot:il length (fide Mudge j 1.040 WiiUIi near the middle 0. 17.") Thickness poateriorly near the middle 0. Ol'i A second specimen, found by myself in the blue limestone-shale in Fossil Spring Cafion, is composed at the base of about twenty-six narrow double rods. A few appear between the others beyond the base, making thirty-one altogether. They are very oblique to the general base, but curve so as to become nearly straight, and enlarge distally. They terminate in a thickened portion, which bears an acute edge, wliich truncates them obliquely. This portion is enameled ; the edge is slightly convex at the base, and slightly concave at a point probably beyond the middle (Plate XLIV, fig. 12). Measurements. M. Length of fragment (12 inches) , 0.30 Width iit the base o.Vi Thickness at the base 0. Ol'J Thickness at the broken end an inch from the edge 0. 007 This is a formidable weapon, and could I)e readily used to s^jlit wood in its fossilized condition. i^^RT III. SYNOPSIS OF THE KNOWN CRETACEOUS VERTEBRATA OF NORTH AMERICA. The following catalogue includes species which have liceii (lerived i'loui all of the members of the Cretaceous formations excepting No. 1, which has not yet yielded vertebrate tbssils. No species has been introduced into the list which has iiol Ijcen descrilx'd, and no genus has been adopted which has not been described. Reference is made to the place where such descriptions can l)e found in botii cases; and, where such citation is omitted, it is understood that the name is provisional only, and that any name employed by the future describer of the genus will be substituted for it in future editions of this list. AVES. NATATORES. HESPERORNIS, Marsh. American Jouiual of Scieuce and Arts, 1872, yi. 360. Hesperornis regalis, Marsh. American Journal of Science and Arts, 187'2, p. .'iti ; /. c, 1872, p. 360. Niobrara group, or No. 3, of the Smoky Hill River, Kansas. GRACULAVUS, Marsh. Gracui.avus anceps, Marsh. American .lonrual of Science and Arts, 1872 (III), p. 3C4. Niobrara Cretaceous of the Smoky Hill. LAORNIS, Marsh. Laornis edwardsianus, Marsh. Aniirican .loiiriial of Science and Arts, Mnreli, 1870. Cretaceous greensand, No F). of New Jersey. 246 GllALL^. PALJiOTRINCIA, Mtush. Pal^oteinga littokalis, Marsh. American Jourual of Science and Arts, Marcb, 18/0. Cretaceous greensand, No. 5, of New Jersey. Pal^eotringa vetus, Marsh. American Journal of Science and Arts, Marcli, 1870. Cretaceous greensand, No. 4, of New Jersey. TELMATORNIS, Marsh. 1'elmatornis PRiscus, Marsh. .\merican Journal of Science and Arts, Marcb, 1870. Cretaceous greensand, No. 5, of New Jersey. Telmatornis affinis, Marsh. American Journal of Scieuco and Arts, March, 1870. Cretaceous greensand, No. 5, of New Jersey. 'I SAURURA. ICHTHYORNIS, Marsh. Ichthyornis dispar, Marsh. American Journal of Science and Arts, 1872, p. 344 (IV) ; and 1873, p. 74 (V), February, 1873. Niobrara Cretaceous of the Smoky Hill. Ichthyornis celer, Marsh. L. c, 1872, p. 406 (IV). — Apatornis cehr (uauio only), I. v., February, 1873. Niobrara Cretaceous of the Smoky Hill. EEPTILIA. DINOSAURIA. CIONODON, Cope. Bulletin of tbo United States Geological Survey of tbe Territories, No. 1, p. 10, Jan., 1874. Ibidm, No. 2, p. 21, April, 1874. CioNODON ARCTATus, Copc. Figured on Plates I and IT. Bulletin of the United States Geological Survey of tbe Territories, No. 2, 1874, p. 21. The Fort Union epoch of Colorado. 247 ClONODON STENOPSIS, Copc. Fort Union epoch of tlio Saskatchewan district, British America. HYPSIBEMA, Cope. Truutiactious of the Auieiicau Philosophical Society, 1870, 1-J'.' (J. HypSIBEMA CEASSI CAUDA, Cope. Extinct Batrachia ami Keptilia of North America, 1S70, p. 122 G ; Report of the Geology of North Carolina, by W. C. Kerr, p. 36 (Appendix B), Plates vi and vii. Cretaceous of Southeastern North Carolina. HADROSAURUS, Leidy. Cretaceous Eeptilcii of the United States, 18C5, p. 70; Proeebdiugs of the Academy of Natural Sciences, Philadelphia, 1850,218. Hadkosaukus foulkei, Leidy. Proceedings of the Academy of Natural Sciences, Philadelphia, 1850, 218 ; Cretaceous Rep- tiles of North. America, Smithsonian Contributions, 1865, p. 76, plates. From the clays Ijelow the greensand of No. 4 of New Jersey, said to belong to No. 1. Haoeosaurus tripos, Cope. Transactions of the American Philosophical Society, 187U, p. 122 I ; Geological Survey of North Carolina, by Kerr, Appendix 15, p. 40, Plate v. From Cretaceous greensand of Southeastern North Carolina. Hadrosaurus minor, Marsh, Cope. Transactions of the American Philosophical Society, 1870, p. 122 J. Cretaceous greensand, (No. 5,) of New Jersey. Hadrosaurus agilis, Marsh. American .Tourual of Science and Arts, 1872, p. 301. From the Niobrara or Cretaceous, No. 3, of Western Kansas. Smaller than the preceding species. Hadrosaurus mieabilis, Leidy. Proceedings of the Academy of Philadelphia, 1868, 191* ; Cope, Extinct Batrachia, etc., 1868, 193. — Tiachodon mirabiUs, Leidy, Proceedings of the Academy of Phi1adci;,!iia, 1856, 72 ; Transactions of the American Philosophical Society, 1860, MO. From the l)ad lands of Judith River, Montana. Known only from teeth. 248 Hadrosaukus occiDENTALis, Leicly. Cope, Extinct. ISiitrai-Iiia, etc., p. 93. — Tlnvpi-^iiix uctu/cw^rt/i.s', Leidy, Proceediugs of tbo Acad- emy of Pliihuk-liibia, lc56, 311 ; Transact ioii.s of tln^ American Philosophical Society, 18fi0, 151. From the lowest meuiber of the Lignite (Fort Union) formation at Grand River, Nebraska. Hadrosaurus cavatus, Cope. Proceedings of the American Philosophical Society, 1871, p. 50. Cretaceous greensaud, No. 5,~of New Jersey. ORNITHOTARSUS, Cope. Transactions of the American Philosophical Society, 1870, p. 120. Ornithotaesus immanis, Cope. i. c, and Proceedings of the American Philosophical Society, 1889, p. 117. Clays below the Cretaceous greeusand, No. 4, of New Jersey, said to be No. 1. AGATHAUMAS, Cope. Proceedings of the American Philosojihical Society, 187-i, p. 482. Agathaumas sylvestue, Cope. Figured on Plates IV, V, and VI. i. c, and Bulletin of the United States Geological Survey, 1874, No. 2, p. 18. Transition Cretaceous, No. (6 or) 7, of Bitter Creek, Wyoming PAL^OSCINCUS, Leidy. Proceedings of the Academy of Philadelphia, 185G, p. 72. Pal^oscincus costatus, Leidy. L. c. ; and Transactions American Philosophical Society, 1860. Bad lands of Judith River, Montana. Founded on dental charjjcters only. TROODON, Leidy. L. c, 185C, p. 72 ; Transactions of the American Philosophical Society, 1800, 147. Troodon fokmosus, Leidy, /. c. Bad lands of Judith River, Montana. Founded on teeth only. AUBLYSODON, Leidy. Proceedings of the Academy of Natural Sciences, Philadelphia, 18G8, p. VJS.—Dinodon, Leidy, /. r., 18GG, 72; not of pumfril. 249 AuDLYSODON iioRRiDus, Leidy. Cope, Kxtinct liatracliia, etc., of Nort'i America, i>. 120. — Dhiodon horridua, Leidy, Proceedings of the Ac-ailemy of Philadelphia, I800, 72; Trausaction.s of the American Philo- sophical Society, ItJCO, 140. — Auhlyeodoii mirandus, Leidy, Proceedings of the Academy 16C8, 198. From the bad lands of Judith River, Montana. Represented by teeth. LiELAPS, Cope. Proceedings of the Academy of Natural Sciences, Philadelphia, 18CH, p. 279 ; American Journal of Science and Arts, 1868, p. 415. L^LAPS AQUILUNGUIS, CopC. L. c, p. 275; Extinct Uatrachia and Reptilia of North America, 1869, p. 100. Greensand, No. 5, of New Jersey. L^LAPS MACROPUS, Cope. Extinct Batrachia and Reptilia of North America, 1670, p. 118 ; Leidy, CretaceouH Rei>tilia, p. 101 (without name). Greensand of Monmouth County, New Jersey. CCELOSAURUS, Leidy. Cope, Extinct Batrachia and Reptilia of North America, i). 119 (name only). CcELOSAURUS ANTiQUUS, Leidy. Cretaceous Reptiles of North America, p. 100 (no name) ; p. 119, name. Table III, fig. I. Greensand of New Jersey. PTEllOSAURIA. PTERODACTYLUS, Cuv. Pterodactylus umbrosus, Cope. Plate VII, figs. 1-4. Proceedings of tho American Philosophical Society, 1872, p. 471 {Ornilhochinis). (Published March 9, 1872.) Niobrara chalk of Kansas. Pterodactylus ingens, Marsh. American .Journal of Science and Arts, 1872, April (published March 7, 1872). Niobrara chalk of Kansas. Pterodactylus occidentalis, Marsh. Plate VII, figs. 5, G. L. c, April, 1872 (published March 7th).— Oniithochirua harpyia, Cope, Proceedings of tho American Philosophical Society, 1872, 471 (published March ^Ihy—PUrodaclyUta oicenli, Mar.sh, /. c, 1871, p. 472, not of Seclcy. Niobrara Cretaceous of Kansas. 32 c 250 Pteeodactylus velox, Miivsli. L. c, April, 187a. Niobruru Cretaceous uf Kansas. CliOCODILIA. HYPOSAURUS, Owen. Journal of the Geological Society of Loudon, V, 383. Hyposaurus vebbii, Cope. Plate IX, fig. 8. Proceedings of tbe Americau Pbilosoi)hical Society, 1872, p. 310. Benton, or No 2, Cretaceous of Kansas. Hyposaurus rogersii, Owen. Journal of tbe Geological Society of London, V, 383, i)late ; Leidy, Cretaceous Reptiles of North America, 1865, p. 18, Table III, ligs. 4-21 ; Cope, Extinct Batracbia and Reptilia of Kortb America, 1859, p. 80. Greensand, No. 5, of New Jersey. TIIORACOSAURUS, Leidy. Cretaceous Reptiles of North America, 1865, \t. 5. Thoracosaurus neoc^sariemsis, DeKay. Gavial DeKay, Annals of Lyceum of New York, Table III, figs. 7-10. — Gavialis ncocwsarieiisis, DeKay, Zoology of New York, 184'2, part III, 1844, p. 82. — Crocudilus «. Gaviahs clai-i- roatris, Morton, Proceedings of tbe Academy of Natural Sciences, 1844, 8'2 ; Giebcl Fauna der Vorwelt, 1847, 122. — Crococlilus hasijlssiix , Owen, Journal of the Geological Society of London, 1849, ]}. 381, Table X, figs. 1-2. — Crocodihis deliaiji, Leidy, Journal of the Academy of Natural Sciences, Philadelphia, II, p. 135. — 2'hotacosaurus grandis, Leidy, Proceedings of the Academy of Natural Sciences, Philadelphia, 1852, p. 35.— Splievomiiriis, Agassiz, /. (•., 1849, 100 (name only). Greensand and limestone of No. 5, in New Jersey. HOLOPS, Cope. Extinct Batracbia and Reptilia, etc., of North America, 1869, p. 67. HoLOPS PNEUMATICUS, Cope. Proceedings of the Academy of Philadelphia, 1872, p. 11. This gavial, as large as the T. neoccesariensis, is represented, so far as I know, by but one specimen ; but this fortunately embraces a large proportion 251 iif tlic oloineiils of tlie skeleton in :i more or less iVagiiientary condition, as is nsual with the Ibssils ()l)taiiu'(l iVoni the greensand excavations. Tlic muzzle was very long and narrow; the mandible convex between the teeth; the |)alat(! Hal. The .surface of the muzzle is grooved, not very closely. The teeth are very much curved, and the section of most of the crowns is round ; i)ut a few posterior ones are flattened on the inner side, so that the section is an unsymmetrical oval. These teeth have acute but some- what shortened crowns; the others are long and acuminate. A delicate angular ridge on the front and posterior aspects divides an inner from an outer liice, of which the outer is more convex. The enamel is marked by a number of shallow, obscure sulci on the middle portions of the crown on both faces; while the surface is thrown into tine wrinkles, so as to resemble silk, which disap})ear from the used portions of old crowns. Twenty-one teeth are pre- served, but the entire number is unknown. The crowns are composed of four, sometimes three, coneiMitric cones. The vertebrae are remarkable for the strong posterior shoulder of the centrum, so that the protuberant ball presents a moi'e than usually contracted i)ase "^riie ball is strongly impressed by a ligamentous pit in the center. The cervicals are relatively very large, exceeding the dorsals and lumbars. In the oidy one which is nearly complete, the centrum is depressed, and hence the articular faces are transverse ovals. The shoulder is oblique to the verti- cal plane. Surfaces smooth. The cup of the first dorsal is nearly round ; its hypapophysis is long, directed forward, and squarely truncate at the end and in front. The parapophysis is below the middle of the centrum, and longitudinal. There are some liiint ridges extending to the shoulder, and a fossa above each parapophysis. The neural arch is coossified. A more posterior dorsal has a hypapophysis with a very large base. The cup is as wide vertically as transversely, but is, like the centrum, contracted in outline below the middle. The lumbars differ from those of other species of the genus in the shortness of the centrum as compared with its other dimensions. They are compressed ; the vertical diameter exceeding the transverse. Of course, the transverse width is the greater near the .sacrum. In the caudal vertebra?, the balls and cups gradually disappear, until a narrow transverse fossa is all that indicates either. One of the terminal caudals is thus truncate at both ends; has tlie sides of the centrum replaced by a deep longitudinal fossa, the base only having some transverse diameter. The neural canal is a tube, one-half 252 of wliich is rooird l)y a saddle-shaped l)ody, and tlir opposite end supports the vertical s})ine, wliicli is (■oiinected with the former by a lamina. Tlie femur is large and has the form usual in the order, and has a hollow shall. Like all the long bones, the dense layer of bone is thin, and the tissue light; surface near articulations always striate-ridged. The tibia has a head subtriaiigular iu. outline, obtuse in front, with a rudimental cnemial spine turned outward, and an open emargination behind. It is penetrated near the anterior angle by a large pneumatic foramen, and the shaft is hollow. The dermal scuta have free, thin margins, and they are coarsely and deeply pitted. Measurements. ir. Length of tbe space coutaiuiuj; Uiroe teeth 0.0 ■iG Width of the uuder jaw at the same point 0. Olio Length of a tooth ou the curve 0 075 Leuj^th of the crowu of the same 0. 0;S:! Diameter of the crowu of the same 0. (Ill Leugth of a cervical vertebra .. . 0. 094 Vertical diameter of the ceutriini 0. 053 Transverse diameter of the centrum 0. OSS Length of the iirst dorsal 0. 07.''> Vertical diameter of the cup of the centrum ....- 0. O.'iS Transverse diameter of the cup of the centrum 0. 057 Leugth of the posterior dorsal 0. 080 Vertical diameter of the cnp 0. 0,")0 Transverse diauieter of the cnp 0. U52 Leugth of the ceutrum of a Inmbar 0. 075 Vertical diameter of the cup of tlie same 0. 0.')2 Trausverse diameter of the cup of the same 0. O-li) Greatest diameter of tbe bead of the femur 0. 078 Least diameter of tbe bead of the femur 0. 0-17 Diameter of tbe shaft of the fenutr 0. 04M Diameter of the head of the tibia, longitudinal 0. 057 Diameter of tbe head of the tibia, transverse 0. 000 This species, in its transverse cervical articular cups, resembles the Ti'io- rncomurus neoccesariensis ; but the diameters of the dorsal vertebrpe referred to that species by Leidy exceed those of the cervicals, while the latter e.Kceed the former in H. pneumaticus. 'Wis gavial also difi'crs in the more acute and cylindric crowns of the teeth, as is the case with other Holojies; while in the T. neoc(Esnriens\s they are more compressed and obtuse. I am not able to determine the jiresence or absence of the lachrymal fossa. The greensand bed No. 5, near Harrisouville, New Jerse3\ Discovered by iny friend Barclay Edwards. HOLOPS BREVISPINIS, Cope. Proceedings of the Academy of Philadelidua, 1867, p. '.\^ ('Tlioracoaaurns) ; Extinct Batrachia, and Keptilia of North America, ISm, p. 69, Plate 1, lig. K!, and IV, 4-0. 253 Greonsand of Now Jersey, No. 5. IToLOrS GLYPTODON, Copo. Kxtiuct Uatiacliiiwiiiil Uiplilia dlXorlli AimiiLM, ISG'.t, pji. 74, 'i.il. Grceiisaiid of New Jersey, No. 5. HoLor.s onscuHUS, Leidy. Crocodilns obscurus, Luiily, Siiiithsoiiiaii Coiitribution.s, Crctaccou.s Reptiles of North Amer- ica, 18G5, p. 115, l'lat(^ II, fi;j. 4. — ThoiacontiiinUi obKriinin, Cope, Geological Survey of New Jeiscy by Cook, A[ipen(Hx C. — Ilolop:i ohsciinin. Cope, Extinct Batracliia and Rf ptilia of North Aiiieriea, 18119, p. 7:'), Plate IV, iif;s. 1-:!. Grceiisaiiil of New Jersey, No. fj. HoLOPS CORDATUS, Cope. Extinct ISatrueliia anil lieptilia of North America, ISIJit, \i. 7;i. Greenland of New Jersey, No. ;'). HoLOPS BASITRUNCATUS, OweU. CrocodihiH iasi/ci(«ea(HS, Owen, Journal of the Geological Society of London, V, 1849, 380. — Crocodilus tenebrosuK, Leidy, Crotaceons Reptiles of North America, 18(i.">, p. 11.'), Plate III, tigs. 12-15. — Hulops lencbrosuH, C(.pe, Extinct Hatrachia and EeplHia of North America, 18G9, p. 78. — H. hasitrtincatus. Cope, 1. c, \i. 2'M ; li;^. 19, p. 77. Greciisaiid of New Jersey, No. 5. BOTTOSAURUS, Agassiz. Cope, Proceedings of the American l'liih;s')i>Iueal Snciety, 1871, p. iK. BoTTOSAURUS JIACRORHYNCHUS, llnrlail. Crncodilnii mavrorliiinchuK, Harlan,. Journal of the Academy of Xatnral .Sciences, Philadelphia, 1824, p. 15. — CrocodiliiH hurlani, Meyer, I'aheologica, 18:i2, 108. — HolliimiHnm harluni, Agassiz, Leidy, Crelaceons Reptiles of Nortii America, 18li5, 12-14. Pl;ite IV, tigs. 19-8:!. — llotlomiinis miicrurliiiiicliiis, Coy.c, Pioeeedings of the American Philosophical .Sjciety, 1871, p. 48 (general osteiilogy). Greensaiid of New Jersey, No. 5. ];OTrO.SAURU.S TUBERtJULATUS, Copc. Extinct IJatrachiaand Rei)tilia of North .\merica, 1870, ji. 2:10; Pnuecdings »ilia of North Anieiica, 18G9, p. 30. PoLYCOTYLUs LATiPiNNis, Cope. Plate VII, fig. 7. E.KliiKt liatiafliiaaiiil Iv'civlilia dl'Norlli America, ISO'.),]), i'.li, Plate I, li'js. 1-13; Hayden's Gen- logical Survey of Wyoaiiii^, l.-^TO, p. :iH8. From llui Ni(il)rar:i chalk of Kansas. CIMOLIASAURUS, Leidy. Dismsaiinin ct Briimmiiinix. Lcidy, Cope, Extinct Batracliia and Rcptilia of North America, 1869, p. 40. CiMOLIASAURUS GRANDIS, Loidy. Cope, X. c, p. ii.—llrimosaunn ymiidis, Leidy, Proceedings of the .\cadcniy of Natural Sci- ences, 1854, p. 7-i, Plate I, figs. 1-3. Cretaceous of Arkansas. CiMOLIASAURUS MAGNUS, Leidy. Proceedings of the Academy of Natural Sciences, 1851, p. 325 ; ihid., 1R54, 72, Plate II, tigs. 4-6; Cretaceous Reptiles of North America, 1865, p. 25, Plates V, figs. 13-19, and VI; Copo, Synopsis of the Extinct Batracliia .and Reptilia of North America, 1869, p. 42, 43. Greensand of No. 5, New Jersey. CiMOLIASAURUS VETUSTUS, Leidy. Cope, Extinct Batrachia and Reptilia of North America, 1869, p. 42. — Discosaurus vdmltis, Leidy, Proceedings of the Academy of Natural Sciences, Philadelphia, 1851, 320 ; Cretaceous Reptiles of the United States, 1865, p. 22. Alabama, No. ?. CiMOLIASAURUS PLANiOR, Leidy. Proceedings of tho Academy of Philivdelphia, 1870, p. 22.— Discosa«n(« re<«8.— Viscosaurus orknlaVat, Leidy, Proceedings of the Academy of Natnr.al Sciences, Philadelphia, 1870, p. 22. Greensand, No. 4, Now Jersey. 256 Elasmosaurus platyurus, Cope. Notes on tlie Geoloj;y iif the Soiilbeiu Division of tbe Pacific Railroad, by .1. Lecontc , 1608, 1 1). 08; Extinct Batracbia anil Rcptilia (if Noitb Anicrie.T, etc., 18!i'J, p. -1 1 ; Haydcn, Geological Snrvey of the Tenjtoiies, 1H70, Wyoiiiinf;, p. li'.W. — Hif^cosniinis airi/Ki/iiv, Cope, Lecoute'rt Notes, /. c. Niobrara Cretaccoii.s of Kansas. PLESIOSAURUS, Conybeare. Plesiosaurus lockwoodii, Cope. Extinct Batracbia and Reptilia of North America, IWiO, p. 40. Cretaceous clays, No. 1, New Jersey. Plesiosaurus brevifemur, Cope, Jip. nov. Ciiiioliasaitnis miifjmis, Leidy, Cope, part ; Extinct Batracbia .and Reptilia of North America, 18G9, 11. 43 ; lig.s. 13-15, p. 41. Greensand of No. 5, New Jersey. Plesiosaurus gulo. Cope. Proceedings of tbe Academy of Philadelphia, 187'2, 128. Niobrara Cretaceous of Kansas. Plesiosaurus occiduus, Leidy. yothosaurtis occiduus, Leidy, Proceedings! of tbe Academy of Philadelphia, 1870, p. 74 ; Report of tbo Geological Snrvey of the Territories (4t(>), 1873, I, i>. 345, Table. XV, figs. 11-13. Lignite Cretaceous of Moreau Eiver, Dakota. ISCHYROSAURUS, Cope. Extinct Batracbia ami Rcjitilia of Norlli America, \S6'd, p. 38. — hclnirotkcriiim, Loidy, Pro- ceedings of the Academy of Philadelphia, 1850, p. 89 ; Transactions of the American Philosophical Society, 1860, p. 150. ISCIIYKOSAIIRUS ANTIQUUS, Cope, /. C. Ixchtjrolhcrium aiifiqnum,^Ani\y,h v.; Transactions of tlio American Philosophical Society, 1*^(10, Table X, figs. 8-17. Liguit(! period l)etwoen Morcan and Grand Rivers, Nebraska. TEST UDIN ATA. PROTOSTEGA, Cope. Proceedings of tln^ American Philosophical Society, 1^71, p. 175 ; /. c, 1872, p. 422. Protostega gigas, Cope, /. c. Plates X, XL XIT, XIII. P^rom tlie Niobrara Cretaceous of Kansas. 257 PliOTOSTEGA TOREUOSA, Copc. Proceedings of llio Aiiicricau Philosophical Society, li-T'J, lin (wlieio Platicnrptis is written {lapsH calami); iiiul Ilayilon's Annual Report ol' the United States Ocolof;ical Survey, 1872, 330, 3:!4. — Atlantochchjs tiihcro.us, Lcidy, Report to the United States Geological Survey oftlie Territories, 4t(), vol. 1, 1873, p. 312. Cretaceous of Mississippi. Proto.stega neptunia, Cope. Proceedings of the American Philosophical Society, 1872, p. •V.V.i.—Allantochdys vtorloiiii, Leidy, Report of the United States Geological Survey of Iho Territories, I, 1873, p. 342; Moaanauius mitchiUi, h^•Ady (pars), Cretaceous Reptiles of tlie United States, 18U5, p. 43, 110, Plate VIII, tigs. 3-4. Greeiisaml, No. *?, of" New Jersey. LYTOLOMA, Cope. Extinct IJatr.uliia and Reptilia of North America, 187(1, p. 144. Lytoloma jeajcesit, Cope. L. c, p. 145. Grecnsand of No. 5, New Jersey. Lytoloma angusta, Cope. L. e.,p. 145; Chelonv sopita (part), Leidy, Cretaceous Reptiles of the United States,]). 105, Plate XIX, fig. 2. Grceiisaud of No. 5, New Jersey. OSTEOPYGIS, Cope. Proceedings of the Academy of Philadelphia, 180.-J,p. 147 ; E.xtinet Batraehia and Reptilia of North America, 1870, p. 132. In this genus, the alveolar surfaces are horizontal, very wide, and entirely ilat. Tlie alveolar edge is not generally reflexed, even at the broadly-rounded apex, but is acute. As already described, there are eleven marginal bones, which, with the pygal, make twenty-three in all. The first and last are witliout corresponding costal bone, so that the number of the latter is nine. I formerly suspected that the eleventh marginal of the O. sopitus is connected with a special costal, the entire number in this species being tints ten ; but subsequent investigation does not establish the view, though it is not j'ct dis- provcn. For the present, therefore, I place this species in Osteopygis. I now add another species to the genus, making the entire nunil)er lour; and (he following tabic points out the distinctive characters: .•J3 c 258 A. Tlio costal pits of" the lateral margins narrow; posterior marginals deeply notched above for the ribs: Surface smooth O. i^latylomas. AA. Lateral costal pits round ; the jjosterior marginals deeply notched above for the riljs: Surface smooth ; lateral marginals low, depressed . . . . O. sointus. Surface coarsely pitted; lateral marginals elevated. . - . O. crosus. AAA. Lateral costal pits round ; the posterior marginals with upper face produced above the rib-pits, con- cealing them ; External border openly notched O. emnrginatus. OSTEOPYGIS PLATYLOMUS, Cope. Extinct Datracliia and Ei>iitilia nf Ninth Aniorica, 1H70, j)]). 135,235. Greensand, No. 5, of New Jersey. OSTEOPYGIS SOPITUS, Leidy. C/ic(oHe sojji'/rt, Leiily,Crotaoeons Reiitiles of Nm-tli Auiorica, It^fiS, i). 104 ; Prophiira soplla, Cope, Extinct Batrachia and Rcptilia of North America, l.'^TO, 110, Plato VII, lig. 4. Grreensand, No. 4, of New Jersey. OsTEOPYGIS EROSUS, Cope, sp. IIOV. The largest species of the genus is represented !)y many specimens from the upper bed of greensand of New Jersey. Although exceeding the O. emarginatus in size, the posterior marginals do not present as high a degree of ot^sification of the interior border. These bones are thin and Hat, while the laterals are very massive, aud have an elevated outer lamina, much exceed- ing the corresponding ones of O. sopitm in this respect, and in transverse diameter below, although tiiey equal them in length. Tlu- pit for the fir.^t costal is at the posterior end of the second margiiial. This, with the first marginal, is coossified to the carapace, as are the pygal and eleventh mar- ginals. The vertebral bones are more than twice as long as wide; are slightly notched before, and obtusely rounded at the narrowed posterior end. The grooves of the dermal scuta are everywhere deeply impressed in this species, and the surface of all the bones marked by numerous pits resembling rain- drop marking, which are somewhat irri-gular in their depths, and not as sharply defined as in most of the f()ssi! Trio/n/chcs. 259 Five vertobrne rxhihif Ihe character of siippnrtiii. Grecnsand, No. 5, New Jersey. Catapleura poxderosa. Cope. Proceedings of the American Philoso])liic:il .Society, l.-i71, p. 40. Green.sand of No. 5, New Jersey. Catapleura ciielydrina. Cope. Os/cojJi/jis c/i(J//rfjiiii()(, Cope, Extinct liatracliia and Reptilia of Nortli America, 1^70, p. 13?, Plate Vll, fi-. 8. The reference of the last twt) species to this genus is not linal, as the essential parts of the skeleton, — tiie anterior co.stal and marginal bones, — are not known. The type-species differs from the Osteopijgis (in all of which the corresponding marginal bones are known) in the absence of any costal gomphosis with the second marginal. 260 PERITRESIUS, Cope. Extinct Batracbia and Roptilia of North America, li-i/O, p. 150. Peiutresius ornatus, Leidy, Cope. L. c, Loidy, Cretaceous Reptiles of the United States, p. 30;!, Plate XVIII, lig. 10. Greensand No. 1 of New Jersey. PNEUMATARTHRUS, Cope. Proceedings of the Anierie.in Philosophical Society, 1870, p. 41(). Pneumatarthrus peloehus, Cope, /. c. Young IHadrosanrm, Leidy, Cretaceous Reptiles of the United States, p. 10(1, Pi.ato XIII, figs. 27-28. G-reensand ?No. 4, Momnoutli County, New Jersey. TOXOCHELYS, Cope. Proceedings of the Academy of Natural Sciences, Philadelphia, 1S73, p. 10. ToxociiELYS LATiREMis, Cope, I. c. Plate VIII, figs. 1, 2. tCijnocercus incisiis, Cope, 1. c, 1872, p. 129; Leidy, Report of the United States Geological Survey of the Territories, I, p. 279, Table XXXVI, figs. 17-21. Niobrara Cretaceous of Kansas. CYNOCERCUS, Cope. Proceedings of the American Philosophical Society, 1872, 308. CyNOCERCUS iNCisus, Cope, I. c. Plate VIII, figs. 3-5. Niobrara Cretaceous of Kansas. TRIONYX, Geoffr. TiuoNYX FOVEATUS, Lcidy. Proceedings of the Academy of Philadelphia, 185G, 73 ; Transactions of the American Philo- .sophical Society, ISliO, 146, Table XI, ligs. 1-2. Fort Union epoch of Judith River, Montana. Trionyx vagans, Cope. Plate VI, figs. 13, 14. llayden's Ijulletiu of the United States Geological Survey, No. 2, p. 29, 1874. Fort Union epoch of Colorado, Montana, and Nebraska. Trionyx priscus, Leidy. Proceedings of the Academy of Natural Sciences, 1851, p. 329 ; Cretaceous Reptiles of tho United States, 18G5, 113, Plate XVIII, fig. 9. Grcensand, No. 4, of New Jersey. 2G1 Trionvx iialopiiili's, Cope. l^ioci;riliii^cs of tlin Academy of Natural Sciences, 18C9, p. Vi ; Extinct Uutrachia and Kcptilia of North America, 1670, p. 151, Plate VII, lix- 15. GicensaiKl, No. 4, of Delaware and New Jersey. PLASTOMENUS, Cope. Annual IJeport of the United States Geological Survey of Montana, Wyoming, otc, 1872, p. G17. Plastomenus coalescens, Cope. Plate VIII, figs. 6, 7. Siijira, !>. 93. Fort Union epoch of Milk River, Saskatchewan, British North America. Plastomenus costatus, Cope. Plate VIII, fig. 8. Supra, p. 94. Fort Union epoch of Milk River, Saskatchewan, British North America. Plastomenus insignis. Cope. Plate VI, fig. 10. Haydeu's Bulletin of the United States Geological Survey, No. 2, 1871, p. '.i'J. Fort Union epoch of Colorado. Plastomenus punctulatus, Cope. Plate VI, fig. 9. Haydeu's Bulletin of tljo United States Geological Survey, 187'l,i). 29. Fort Union epoch of Colorado and Nebraska. COMPSEMYS, Leidy, Cope. Siqini, p. 91. CoMPSEMYS OGMIUS, Cope. Supra, 1). 91. Fort Union epoch of Milk River, British North America. Compsemys victus, Leidy. Plate VI, figs. 15, 16. Pi'occcdings of the Academy of Natural Sciences, Philadelphia, lS5(i, p. IU2 ; Transactions of tl'.e Americau Philosophical Society, 1800, p. 152, Plate XI, fig. 557. Fort Union epoch of Nebraska, Colorado, and ?Milk Rivur. British Nortli America. Compsemys obscukus, Leidy Emi/s obscm-us, Leidy, Pic ohscurus. Cope, Exti Fort Union epoch of Lon^' Lake, Nebraska. Emi/s ohscurus, Leidy, Proceedings of the Academy of riiiladeliihia, 185G, 312. — Comj)scmij8 oiscHriis, Cope, Extiuct Batracliia and Keplilia of North America, 1870, 121. 262 AGOMPPIUS, Cope. Procucdiiigs of tUo Amoricau Pbilosoiiliical Society, 1^71, ii. 4G; lliiydcu'a Annual Report of tho United States Geolojjioal Survey of tbe Territories, 1872, i>. C'J.'i. Agosiphus tukgidus, Cope. Eimjs turgidus, Extiuct Batracliia and lleptilia of North America, 1S70, p. l'^7. G reuiisaiitl, No. 5, of New Jersey. vVgomphus petrosus, Cope. .Bftii/s ^>e(ro8H», Coiic, Proceedings of tbe Academy of I'biladclpbia, IblJH.iJSO ; Extiuct 15atra cbia and Reptilia of Nortb America, 1870, IdG. Greensand, No. 5, of New Jersey. Agompiius firmus, Lekly. Eintjs Jlnnus, Leidy, Cretaceous Reptiles of tbe Uuited States, 1605, p. KKi, Plate XIX, lig. 3. Greensand of New Jersey, No. 5. ADOCUS, Cope. Proceedings of the Academy of Natural Sciences, Pbiladelpbia, 1808,235; Extinct liatracbia and Kcptilia of Nortb America, 1870, \^. 232 ; Proceedings of tbe American Pbilosopbical .Society, 1870, p. 547. AUOCUS PECTORALIS, Cope. Extiuct Batracbia and Reptilia of Nortb America, 1870, p. 233, Plate VII, lig. 1. — I'Uuro- sternum pcctonih; Coi)c, I. c, p. 130. Greensand, No. 5, of New Jersey. Adocus pravus, Leidy. Cope, ?. o.,p. 234. — &)i^.5 j))'arHs, Leidy, Cretaceou.s Reptiles of tbe Uuited Slates, 1805, 108, Plate XIX, iig. 1 ; Proceedings of tbe Academy of Pbiladelpbia, 1850,303. Greensand of New Jersey, No. 5. Adocus beatus, Leidy. Cope, I. c, p. 233.— A'hi^s bcalus, Leidy, Extiuct Batracbia and Reptilia of Nortb America, 1805, p. 107, Plato XVIII, figs. 1-3. Greensand, No. 5, of New Jersey. Adocus syntiieticus, Cope. Proceediugs of tbe American Pbilosopbical Society, 1870, p. 548. Greensand, No. 5, New Jersey. Adocus agilis, Cope. Extinct Batracbia and Reptilia of Nortb America, 1870, i>. 108. Greensand of New Jersey, No. 5. 2(53 Adocus linkolatus, Cope. Pktc VI, figs^. 11, 12. HayUf n'H UulUtin of tbo Ui.itc.l States Geological Survey of ll.u Territories, No. i, lb74, p. CO Fort IJiiiua epoch oi" Montana, Colorado, and ? Saskatchewan. ZYGORAIMMA, Cope. Proceeiliu;;.-; of the American VhilosopUical Society, 1870, 550. Zygouamma stiuatula. Cope, /. C. Grcensaud. No. 5, New Jersey. ZyGOKAMMA MICKOGLYPHA, Co[)e. i. f, 187 1,1). 44. Gieensaud, No. 5, of New Jersey. HOMOROPHUS, Cope. ProcccaiuRS of tbe Americau Philosophical Society, IWn, p. iTil. ' HoMOROPiius iNSUETUS, Cope. L. c, 5.32. Greejisand, No. 5, oC New Jersey. BOTH REM YS, Leidy. Cretaceous Keptiles of the Uuitetl States, Iblju, l'. UU. BoTiiuEMYS cooKii, Lcidy. L. c, Plate XVIII, li;,'s. 4-8. Greeusaiul, No. 4, New Jersey. TAPIIROSPHYS, Cope. Extinct Batrachia and Urptilia of North America, 1870, i>. l.V ; American Naturalist. IStil), p. 'Ml TapuFvOSPiiys MOLOPS, Cope. Kxtmet Ijatrachia and Keptilia of North America, 1870, p. l.'iit, Plate VII, lig. 1(3. Couimon ill greciLsand of No. 5, New Jersey. Tapiiuospuys longinuc'hus. Cope. L. c, IG-3. Grcensand of No. 5, New Jersey. Tai'iikospi'ys sulcatus, Leidy. Coiic, 1. c, \t. 104. — riataniju mtlcuUin, Lciily, Proccciliiigs of llju Aciiikiiiy ul' Pliil;uU'liilji;i, 1650, oUL! ; Crctaceoiu^ Koi>til('S ol'tlic Uiiitcil States, lbG5, lOll, Platu XIX, 11;;. 4. Grucusand of No. 5, New Jersey. Tapiiuospuys leslianus, Cope. Extinct Batracliia auil Itcptilia of North Amurica, lb70, \i. KiG. Grcensaiul of No. 5, New Jersey. TApiiKoypiiYS STEENUUS, Cope. Extinct BatracUia aud Ucptilia of North America, 100 1!, Itf/l). Gieeusar.d, No. 6, of New Jersey. TaPUKO.'^J'IIYS nodosus, Cope. L. c, p. IGG C, Plate I, li-;. IG. Greeiisaiid below No. 5, New Jersey. PYTIIONOMOIIPIIA. Tlie (juadratc bones of the species of this order are represented in Plate XXXVII In coinpletit)n of tlie description of this portion of the skeleton, I wonld point out the coincidence l)etWeen the forms of tiie cpiadratc bone and other characters employed in the preceding pages, as indicative of generic divisions. To the ridges already described, I wonld add that the "mcatal Iviiob" o? Mosasaurus is represented Ijy a ridge or crest in Liodon, and by one less marked in Clidasfes ; and hence the term "knob-ridge" may be added. The lower part of the great anterior ala turns Ijackward, and is generally continued upward on the outer and anterior side of the knob-ridge ; this may be called the "posterior alar" ridge. We then have : proximalli/, the alar pro- cess : the internal angle; aud the internal longitudinal ridge; distuUij, Ijegin- ning in front, the posterior alar ridge; the knob or knob-ridge; median posterior ridge ; and the distal longitudinal ridge. Mosamu?-us differs from all the other genera in the absence of the inter- nal longitudinal ridge. No other genus is known to ])ossess the median pos- terior ridge, nor is the knob of the same form in any other. M. fulcidtus is the only species of the ordiu- in which all four of the distal ridges are pnjsent. In M. 7naximus, the knob is wanting; and in J/, giganlcus, the median poste- rior ridge is not found. 111 Platccarpus and Clidustes, llic kiioh-ridgo is low and ends obtusely not I'ar above; the. distal condyle, and the posterior alar is very prominent. In Liodun, the knob-ridge is much iiion; prominent, and Ibrins a protuberant angle below the position of the "knob" in Moi^amurus, which is continued by a decreasing crest to the distal condyle. This ridge, with the equally prom- inent posterior alar, causes a protuberance on the posterior part of the quad- rate, between the meatus and the distal condyle, which is especially marked in the Liodon validus. In the three genera mentioned, the position of the median posterior ridge is occupied by a concave surface. CUdastes planifrons, Coj)c, is intermediate in (he Ibrni of its quadrate hone, between such tonus as C. tortor and the Platecarpi. Its internal angle and ridge are less promi- nent than in C. tortur, and a part of it extends so near to the stapedial pit as to have led me to call it (he median posterior r-idge in my original descrip- tion, an error I now correct. Flatecarpus tynqyaniticus is closely similar to the Kansas species of the genus in the form of this element. In the Ibllowing list are included a number of names of species which I have not seen. Those described by Dr. Leidy and myself I believe to l)e distinct from each other and from those described by the older authors. CLIDASTES, Cope. Pioceecliiij,'s of thu AcaUeiiiy of Pliilailelpbia, 1868, 1). '233; Trausactious of thu American riiilosopliical Society, 1870,211. — iJdc^/osaH)-««, Marsb, American .Journal of Science ami Arts, 1871, Juno; Cope, Proceedings of tbe American Pliilosophical Society, 1871, December. I. Frontal hones without median keel; dorsal vertcbrce depressed: Clidastes PLANIFRONS, Cope. Plate XXII ami XXIII, Dgs. 1-11. llaytlen's Bnllcliu of tlie United States Geological Survey, No. '2, 187-1, p. 31. Niobrara epoch, Kansas. II. Frontal hones with median keel; dorsul vertehrcc (Upressed: Clujastes puopvtiion. Cope. Proceedings of tbe Uoston Society of Natural History, 18G0, p. 'i")8; Extinct IJalracbia ami Keptilia of Nortb America, 1870, p. 221, Plato XII, figs. 1-21. Rotten limestone, "No. 4," of Alabama. Cliuastes tortor, Cojie. Plates XIY, lig. 1 ; XVI, ligs. 1, li; XVII, lig. I; XIX, figs. 1-10; XXXVI, fig. 3; and XXXVII, fig. 2. Eden'osaurtts (ortor, Cope, Proceedings of tbe American I'liilusupliical Suciety, Ueecnjljcr, 1871. Nioi)rara Cretaceous of the Smoky Hill River. 34 0 266 ClidaSTES STENOPS, Cope. Plates XIV, tigs. 4, 5; XVII, figs. 7, 8: XVIII, tigs. 1-5 ; XXXVl, lig. i ; XXX VII, tig. 3; XXXVIII, tig. 3. Edcatosauru8 slenops,}. c, llaydcn'a Anuw.\\ litiiwrl of tbo Uuituil Status Goological Survey, 1871, p. 330. Niobrara Cretaceous; of the Smoky Hill River. Clidastes eex. Marsh. Aiuericau Jourual of Scicuco aud Arts, 1072, Jimc. Niobrara Cretaceous of Suioky Hill River. Clidastes affinis, Leidy. Koiiort of tUo United States Geological Sui'voy of tlm Territories, I, p. 2H1 , Table XXXIV, iigs. 6-'J aud 11. Niobrara Cretaceous of Smoky Hill River. ni. Dorsal vertebra, with depressed eentra.: froiita/ hones unknown: Clidastes dispar, Marsh. EdestoSMiriis dispar, Marsh, Auicricau Journal of Science aud Arts, 1871, Juno. Niobrara Cretaceous of the Smoky Hill River. Clidastes velox, Marsh. L. c. (Edusloaaurua). Niobrara Cretaceous of the Smoky Hill River. Clidastes vymanii, Marsh, I. c. Niobrara Cretaceous of the Smoky Hill River, Western Kansas. Clidastes pumilus, Marsh, I. c. Niobrara Cretaceous of the Smoky Hill River. Clidastes iguanavus, Cope. Proceedings of tbe Acadeuiy of Philadelpliia, ISUy, p. 223; Extinct Datracbia aud Keptilia of North America, 1S7(I, p. 220, Plate V, lig. 3. Greensand, No. 4, of New Jersey. IV. Centra of dorsal vertebrts compressed: Clidastes cinekiakum, Cope. Plate XXI, tigs. 11-17. Proccediugs of the Auiericau Philosophical Society, 1870, 583. Niobrara Cretaceous of the Smoky Hill River. 207 V. Dorsal mrt.ehra and frontuLs unkown; haaca of some dental crowns swollen : Clidastes intermedius, Leicly. Prococdiuss of tUo Acaacny of IMuhulclpbia, 1870 (January); Kcpoit ou tb. lluitea States Gcolo{;ical Survey of the Territories, 1873, I, v. 281, Vlatc XXXIV, figs. 1-5. Rotten limestone, Pickens County, ALabanui, "No. 4.'' SIRONECTES, Cope. bulletin of the United States Geological Survey of tbo Territories, lf<74, No. "i, l-. :!1. SlUONECTES ANGULIFElUJS, Cope. Plate8 XXIII, figs. IC-IS ; XXIV, flj,rs. 1-U. L. c, p. 34. Niobrara Cretaceous of Kansas. PLATECARPUS, Cope. Extiuc-t Uatraobia and Keptilia of Nortb America, 1870, w 18^., I'J'J ; Proceedings of ''''^ ^cademy of I'Uila- delpbii 1872, p. U\.-nokodm, Copo, ncc Gibbsii, Troceediugs of tbo American Pb,los< pb.u.l boci- ety, 1871, Dcceml.er.--tf.')(osa«)»s, Mar.sb, American Journal of Soioncc alul Arts, 1872 (Juno); (sei*- arata, p. 9). a. The staiKdLal pit incloml he f ween ridges: PLATECARPUS ICTEKICUS, Cope. Plates XIV, lis. 0 : XV, fig. 2 ; XXII, figs. 3, 1 ; XVIII, tig. G; XIX, fig. 9; XX. fig. 1 ; XXV ; XXXVI, fig. 7 ; XXXVII, fig. 8. IM,.Klu» ictcricm, Cope, Proceedings of tbo American Pbilosopbical Society, 1670, 577, and 1871, December.-iesfosaiinis Iciericus, Marsb, American Journal ot Science and Arts, 1872, .^n\w Niobrara chalk of riic 8iiioky Hill Kiv.T. PLATECARPUS CORYPii.EUS, Cope. Plates XIV, fig. 3; XV, fig. 1 ; XVI, fig. 1; XVII, fig. G; XX, fig. 4; XXI, tigs. 1, 2; XXXVI, fig. G; XXXVII, fig. 9. Uohodm cowft«,.s, Cope, Proceedings of tbe Anierican Pbilosopbical Society, 1671, Decem- ber.—i«s(osaM>-H.i coryplKciis, Marsh, /. c. Niobrara chalk of the Biiioky Hill River. PlatecaPvPUS TYMPANiTicus, Cope. Plate XXXVII, fig. 11. Proceedings of tbe Boston Society of Natur.al History, ISft., p. 2(m ; Extinct Batracbia and Rep.ilia of Nortb America, 1870, p. 200.-//«;c..;«,s «.«/,*».,'' Gi '^-."L-'y- "' 1-^; Cretaceous Reptiles of tbe United States, ].. 118, Plate Vll, 4 / ; VUl, b^. 1---/. XI, 14. Cretaceous, No. !, of Mississippi. PLATECARPUS FELIX, Marsll. to(o,«mn,., /,;,>, Marsb, American Journal of Science and Arts, 1872, .June, Table Xlll, f.g. 4. Niol)rara chalk of the Smoky Hill River, Kansas. 268 PlATECARPUS CURTIUOSTRIS, Cope. Plates XlV,^fig. 2; XV, tig. 3; XVI, figs. 5,0; XVII, fig. 2; XVIII, figs. 7, 8 ; XXI, fig. S; XXXVI,fig.5j XXXVn,fig. 10; XXXVIII, fig. 1. Liodon curtiroatris, Cope, Proceedings of the Auiericau PhilosopUioal Society, 1871, December. — Lestosanrus curtiroatris, Marsb, I. c. Niobrara chalk of the Smoky Hill River, Kansas. aa. Relations of stapedial pit unknown : PlATECARPUS CRASSARTUS, CopC. Plate XXVI, figs. 1-12. Liodon crassartiis, Cope, Proceediuys of the Auiericau Philosoj)hical Society, 1871, 1G8, aud December Niobrara chalk of Eagle Tail, Colorado. PlATECARPUS simus, Marsh. Lestosaunis aimnii, Marsb,/. c, 1872, Juuc. Niobrara chalk of the Smoky Hill River. PlATECARPUS latifrons. Marsh. Lcsloaaurus latifrona. Marsh, 1. c, 1872, Juue. Niobrara chalk of the Smoky Hill River, Kansas. PlATECARPUS GRACILIS, Marsh. Lcslosaiirua gracilis, Marsb, I. r., l,--!72, .June. Niobrara chalk of the Smoky Hill River, Kansas. PlATECARPUS? LATISPINIS, CopC. PLltC XXVI, fig. 1-G. Liodon hiiispinis, Cope, Proceedings of tlie Amcrieau Pbilosopbical Society 1871, p. Hid ; 1871, December. PlATECARPUS ? GLANDIFERUS, Cope. Plate XXVI, figs. 13, 14. Liodon (/landifcrus, Cope, Proceed! ugs of tlio Aiiicricau Pliilosophieal Society, 1871, Uece;iiber. Niobrara beds of the Smoky Hill River, Kansas. aaa. Staj'edial j)it excavated in a plane surface: PlATECARPUS MUDGEI, Cope. Plates XVI, fig. 3; XVII, fig. 5; XXVI, fig. 3; XXXVII, fig. 7. Liodun mudgci, Cope, Proceedings of the Americau Philosopbical Society, 1870, ji. 581. — Hotco- diis mudgci, Cope, J. c, 1871, December. — Rhinosaurua mudgci, Marsh, Americau Jourual of Science aud Arts, 1872, Juue. Niobrara chalk of tlie Smoky Hill River. 209 PLATlCCARrUS TKCTULUS, Copo. Plates XXI, fiS- 3-0 ; XXVII, fif,'s. 5-10. llolcodns teeMtts, Proceedings of the American Pliilosophical Society, lti7 1, 1 Jeccnilnr. Niobrara clialk of tho Smoky Hill River. MOSASAUUUS, Conyl). Cuvier, Osseniens fossilcs, X, i>. ll'.i. a. Species with articular faces of dorsal vertebra; suhround: MOSASAURUS MAXIMUS, Copc. Plate XXXVII, lig. lo. Extinct Batrachia and Reptilia of Nortli America, 1670, p. 180, Plato XI, li;;. 7. Greensand of No. 4 of New Jersey. MosASAURUS DEKAYI, Brouu. Plate XXXVII, fig. IG. Lethaia Geoguostica, 1S3S, from DcKay, in Annals of tlic New York Lyconni, III, p. \X}.— Mosataurus major, DoKay, Geological Survey of New York, 1841.—? .1/. cnroliiiamn and f M. coiqycrii, Gihhca, Smithsonian Contribniions to Knowledge, vol. II, p.fi, plate. — Mosasaunis mitchillii, Lcidy, Cretaceous Reptiles of the United States, 180.'>, p. 118, plates pro parte ; Proceedings of tlic Academy of Natural Sciences, Philadeliiliia, 1S59, p. 90. — Baseodon rtrcrsiis, Leidy, Cretaceous Reptiles of the United States, p. 118, Plato X, tigs. 14-15. — 1 Mosasaunis 2»'iiiccps, Marsh, American .Journal of Science and Arts, 1869, :&2; Cope, Extinct Batrachia and Reptilia of North America, 1870, 192,235. Grcciisaiid of New Jersey, No. 4 and ?No. 5 ; South Carolina ? (Gibbes). MoSASAURUS FULCIATUS, Cope. Plate XXXVir, fig. 13. Extinct Batrachia and Reptilia of North America, 1870, p. 194. Greensand of '? No. 4, New Jersey. aa. Species with articular faces Qf dorsal vertchroi transverscli/ oml : MoSASAURUS OARTIIRUS, Cope. Plate XXXVII, fig. 17. Extinct Batrafhia and Reptilia of North America, 1870, p. lUlI. Greensand of No. 5, New Jersey. MoSASAURUS MissuRiENSis, Harlan. Ichlhi/usaurus missurknsh, Harlan, Transactions of tho American Philosophical Society, 1834, vol. IV, p. 405, Plate XX, tigs. 3-3.— Mosasaurus ncovidii, Goldfuss, Deutsche Natnr- forscher Versammhuig zu Mainz, 1848, 1, 141. — Mosasanriis maximUiani, Goldfuss, Nova Acta Acad., K. L. C. Nat. Cur., XXI, p. 179, Plates VI, VII, VIII, IX.—Mosumurun mix- siirlensis, Leidy, Proceedings of the Academy of l'hiladeli)hia, tS."!?, 90 ; Cope, Extinct Batrachia and Reptilia, of North America 1870, p. 195, exclusive of .specimen from Kansas. Cretaceous, ?No. 4, of the Missouri River. MoSASAURUS DEPRES.SUS, Copc. Plate XXXVII, lig. 12. Extinct Batrachia and Reptilia of North America, 1870, VXi. Greensand, No. 4 or 5 % New Jersey. 270 aaa. Sper.'ies hnown (diIij from icclli mid jiaiis of cvnnki : MoaASAURUs ACUTiDENS, Gibbes. ffolcodus acuiidcns, Gibbcs, iiro jiarto, Smithsonian Coutiilmtious, 11, p. 0. 1'lati: III. figs. (i-O. ? Mosasaurus minor, Giblx's, I. c, p. 7, Plato I, (igs. \i-'>, 1S51. CretaceuiLs of Alabama. Mosasaurus copeanus, Marsh. American Jouraal of Science and Arts, 1869, 398; Cope, Extinct Batracljia and Reptilia of North America, 1870, p. 198. Greeiisaud, No. 4, New Jersey. Mosasaurus crassidens, Marsh. American Journal of Science and Arts, 1870, February .and JIareU ; Cope, E.xtinct Hatraehia and Reptilia of Nortli America, 1K70, 108. Greensaiid of North Carolina. aaaa. Species of loicertain reference : Mosasaurus miersii, Marsh. American .Journal of .Science and Arts, ISG'J, :i95. Greensaiid below No. 5, New Jersey. Mosasaurus bruimbyi, Gibbes. Cope, Extinct Batrachia and Reptilia of North America, I-'7(l, p. 198. — Amplioroslcus lUiituhiji, Gibbes, Smithsonian Contributions, II, 1851, \k 9, Platen III, (Ijjs. 10-lG. Cretaceous of Alabama. LIODON, Owen. Proceedings of the British Association for the Advancement of Science, 1811, p. 141 ; Cope, Tr.ansactions of the American Philosophical Society, Extinct Batrachia, etc., 1870, p. 200 ; I'roceedings of the American Philosophical Society, 1871, December. a. Species with (he dorsal vertebral centra com])resscd ; Macrosaarus, Owen : LiODON LiEVis, Owen. Macroaaui-us Iwvis, Owen, Journal of the Geological Society of London, 1819, iisO, plate. — Liodon Iwvia, Cope, Extinct Batrachia ami IJepUlia of North America, 1870, 21)5 (exclusive of Lockwood's specimen). Grcensand, No. f, New Jersey. LiODON MiTCiiiLLii, DeKay. Gcosaurus mikhiUU, DeKay, Annals of the Lyceum of New York, III, p. hlO.—Mosmsaiinis mitchillii, pro parte, Leidy, Cretaceous Reptiles of I lie United States, p. O.'i, Plate XI, figs. 1-4; Cope, Proceedings of the Boston Society of Natural History, 18G9.— /)n7;f(- nodon biqmr, Leidy, Proceedings of the Academy of Philadelphia, 1850,25.') —Lfftlico- dtts impai; Leidy, Geological Survey of North Carolina, p. 224, figs. 4.5-40, /r/c Leidy. This species is at least twice as large as the L. hcim, equaling the largest . ol tlu; order. Much of the cranium remains uukiiown, but isolated teeth are 271 rather coiiiinoii. The hirgc spociineiis noted l)y me as al)()ve, umlcr //. hcvis, l)r()l)al)ly l)('h)iig here. Greensaiid, No. 4, of New Jerse}-. «■ aa. Species wUh the dorsal centra depressed ; Nectoportlieus, Cope : LlODON VALIDUS, Cope. Plato XXXVII, fig. 4. Kxtiuct liatr.icliia ;iiul lloptilia of Ni>rtli Aincric:\, 1^70, p. 207. — Ncclojinrlhcnn ralidus, C'opp, Procoediugs of tlio Acaileiiiy of Natural .Sciences, riiilailclpliia, 18(!.-(, l-'l. — Mov<(miini3, Leidy, pro parte, Cretaceous Eeptiks of the Uniteil States, 18G5, p. 71-75, I'late VII, iy-20, III, 1-2. Greensantl. No. 5, New Jersey. LlODO.V MICROMU.S, Maish. Jthinonaiinin micromiis, Mar.sli, Aiiirrican .Journal of Science anil Arts, 1S72, .Inne, Talili' XIII, ligs. 1-2. Niobrara ehalk of the Smoky Hill. LlODON NEryEOLicus, Copc. Plate XXXV, figs. 11-13. Ilayden's IJulletin of the United Staes GooUiKical Survey of tlie Territories, l.'*7-l, p. H7. Niobrara epocli of Kansas. LlODON PKOKIOER, Cope. Plates XXVIII, figs. 8, 9 ; XXX, fig.s. 10-14 ; XXXVI, lig. 2; XXXVII, lig. G. Trausactious of the American Philosophical Society, Extinct liatracliia, etc., 1870, p. 202. — Macroiaiirus proriger, 1. c, on Table XII, figs. 22-21. — Ilhinosaitriis proritii'i', Marsh, Amer- ican Journal of Science and Arts, 1872, Jnne. — Sltamphonaiiri(s, Cope, Proceedings of the Academy of Natural .Sciences, 1872, p. 141. Niobrara cluilk of the region of the Sinol^y Hill River, Kansas. LlODON DYSPELOB, Cope. Platt'S XXVIII, figs. 1-7; XXIX-XXXIII. Proceedings of the American Philosophical Society, 1870, .')74 ; J. c, 1871, Deccmher. — lihino- saiinis dyspclor, Marsh, American .Journal of Science and Arts, 1872, .June. — Ti/losaiini/i dijspclor, Leidy, Report of the Geological Survey of tlic Territories, I, p. 271, Talde XXXV, ligs. l-U. Nioljrara chalk of Fort MeRae, New Mexico, and of Smoky Hill, Kansas. LlODON SECTORIUS, Cope. Proceedings of the American Philosopliieal Society, 1871, p. 11. Greensand, No. 5, of New Jersey. aaa. Species of U7icertain reference : LlDDON PERLATUS, Copc. Proccodings of the American Philosophical Society, 1870, p. ■4',t7. — Mosasauriis hritmbi/i, " Gibhe.s," pro parte, Cope, Extinct P.atraehia and Keplilia of North America, !>-^7il, p. 108. White limestone of Alabaiiia. 272 LlODON CONGROPS, Copo. Extinct liatraeliia siikI Rpptilia of NdvIU America, 1870, ji. 200. Perhaps a Clidastes. Rotten limestone of Alabama. DIPLOTOMODON, Lcidy, ProcofidingH of the Academy of Natural Sciences, 1838, p. 202. — Tomodon, Leidy, Cretaceous Reptiles of the United States, 1865, 102, not of Dumdril, 1803. — ? , Cope, American Journal of Science and Arts, 18C8, p. 417. DiPLOTOMODON HOKRIFICUS, Leidy. L. c, Tomodon horrificus, Cretaceous Reptiles of the United States, 102, Plate XX, i\^n. 7-'J. Greensand, No. f, of New Jersey. BAPTOSAURUS, Marsli. Proceedings of the Academy of Pliiladelpbia, 1870. — Iltdisaurus, Marsli, American Journal of Science and Arts, 1801), 395, hoc Johiisoiiii. — Baptosaiii-us, Cope, Extinct Catracbia and Reptilia of Nortli America, 1870, 208. Baptosaurus platyspondylus, Marsh. Cope, 1. c.,209. — Macrosaurus jplaUjspondijlus, Mar.sli, Proceedings of tlie American Association for the Advancement of Science, 1800. — UaHKauntif plnti/npondi/htu, MarsL, American Journal of Science and Arts, 1800, 395. Grreensand, No. 5, of New Jersey. ' JWtosaurus fraternus, Marsh. L. c, 307; Cope, I c.,210. Grcensand, No. 5, of New Jersey. PISCES. PERCOMORrill. BERYX, Cuv. R&gne anini.al, 1817 ; Agassiz, Poissons fossilcs. Beryx insculptus, Cope, riato LII, lig. 4. Proceedings of the American Philosophical Society, 18G9, p. 240. Greensaiid of No. 5, New Jersey. 273 PERCESOCES. SYLL.liMUS, Cope. R.,.o..t on ,h. ris).cs coUeotea ,,y ...c rnit.l S.ates Goo^.^.^ai and Oco,..«i.. «u.v..y ..f ,...■ One HuiuUcdtli Meridian, lS. Same locality as Uie hist. 274 PORTIIEUS LESTRIO, Copo. I'lalt'S XLII, figs. 1-.'!; XLVII, figs. 1-5. Proceedings of the Academy of Natural Sciences, Pliiladclpliia, 187:?, \t. 337. Niobrara Cretaceous of Kansas, near the Solomon Iiiver; abundant. PORTHEUS MUDGEI, Cope. Hayden's Bulletin of the United States Geological Survey of the Teiiitories, No. 2, 1S74, y. 40. Niobrara group of Kansas. PORTIIEUS ARCUATUS, Cope. Plate XLYII, fig. 7-0. Sujpra, r. 204. Niobrara group of Kansas. PoRTHEUS GLADIUS, Cope. Plate LII, fig. 3. Prooeediugs of tlie Academy of Natural .Sciences, Pliiladclpliia, 1873, 338. Represented by a huge pectoral spine, which may l)el(mg to one of the preceding species. Niobrara Cretaceous of the Solomon River, Kansas. ICHTHYODECTES, Cope. Proceedings of the American Philosophical Society, 1870, Novcinlicr; J. c, 1872, p. 338. IcHTiiYODECTES ANAIDES, Cope. Plates XLIV, figs. 14, lo ; XLV, figs. 1-S. L. c, 1872, 339. Niobrara Cretaceous of the Smoky Hill. ICHTIIYODECTES CTENODON, Cope. Plate XLVI, figs. l-i. L. c, 1870, November ; 1. c, 1872, 340. Niobrara Cretaceous of the Smoky Hill. IcnXHYODECTES HAMATUS, Copc. Plate XLYI, fig. 5. X. c, 1872, 340. Niobrara Cretaceous of the Smoky Hill. IcHTHYODECTES PROGNATHUS, Cope. Plate XLVI, figs. G-IO, L. c, 1872, 3il.—SauroccpIi(ihis itrognathiis, Proceed 1870, November. Cretaceous (Niobrara) of the Smoky Hi L. c, 1872, 341. — Sauroccphtihis iirognallnis, Proceedings of the American Pliildsdiiliicil Siicicty, 1870, November. 275 l(MirilY()l)ECT!:S MULTIDENTATUS, Copo. I'lillc L. lis«. 0. 7. L. c, 187->, i>. ■■»•>. Cretaceous (Niol)riira) of the SiiioUy Hill. ICHIIIYODECTICS PKRNICIOSL'S, CopC. Plate LII, liff. 2. IliilU'tiu of till! Uiiiteil States Geological Survey of the Territories, No. 2, IHT-I, p. 41. Niobrara group of" Kansas. DAPTINUS. Cope. Proceedings of the Academj- of Philadelphia, 1HT3, (i. XVi. Daptinits piilehotomus, Cope. Plates XLVIl, lig. G; XLIX, ligs. l-l. SaiiroccphalHS j>lihbotomu8, Cope, Proceedings of tho American Philosophical Society, 1870, November; Hayden's Annual Report of the United States Geological Survey, 1871, p. 4 If). Niobrara epoch, Ro(jks ami Phillips Counties, Kansas. SAUROCEPHALUS, Harlan. Saurocephalus lanciformis, Harlan. Journal of the Academy of Natural Sciences, 1, vul. Ill, 331 ; Leidy, Transactions of llie American Philosophical Society, 1860, p. — . Cretaceous on the Missouri River. Saurocephalus arapauovius, Cope. Plate XLIX, tig. 5. Proceedings of the American Philosophical Society, 1872, p. 343. Niobrara epoch of the Smoky Hill, Kansas. SAURODON, Hays. Transactions of the American Philosophical Society, 1830, p. 470. Saurodon leanus, Hays. L, c, Plato XVI. — Saurocephalus leanus, Leidy, I. c, 185G. Greensand of No. 5, Nevv Jersey. ERISICHTHE, Cope. Proc(^ediuga of tho Academy of Philadelphia, 1872, 2-0. Erisichthe nitida, Cope. Plate XLVIII, figs. 3-8. L. c, and Haydeu's Bulletin of tho United States Geological Survey of the Territories, No. 2, p. 41, 1874. Niobrara group of Kansas. Erisichthe angulata, Cope. Porlheus aniiulalus, Copo, Proceedings of tho Americau Philosopbical Society, 1872, p. 337 ; Geological Survey of North Carolina, Appendix I?, p. 32. Cretaceous, No. ?, of North Carolina. 276 XIPHACTJNU8, Leidy. XiPHACTiNUS AUDAx, Leidy. Procecdiugs of tlio Academy of Philadelphia, 1870, IS ; Report on the Geological Survey of the Territories, 1873, I, p. yOO, Plate XVII, fi>.r.s. 9-10. Niobrara epoch of Kansas. PACHYEHIZODUS, Agassiz. Dixon's Geology of Siis.sex, 1850, i). 374; Cope, Proceediiig.s of the American Philosophical Society, 1872, p. 344. Pachyrhizodus caninus, Cope. Plate L, figs. 1-4. L. c, 344. Niobrara epoch of the Smoky Hitl River. Pachyrhizodus kingii, Cope. PlateXLVl, fig. 11. L. 0., 340. Niol^rara epoch of the Smoky Hill River. Pachyrhizodus latimentum, Cope. Plates L, fig. 5; LI, figs. 1-7. L. c, 340. Niobrara epoch of the Smoky Hill, and of Phillips County, Kansas. Pachyrhizodus sheareri, Cope. Proceedings of the American Philosophical Society, 1872, p. 347. Niobrara epoch of the Smoky Hill River. Pacmyehizodus leptopsis, Cope. Plate LI, fig. 8. Hayden'.s Bulletin of the United States Geological Survey of the Territories, No. 2, 1874, p. 42. Niobrara epoch of Kansas. CONOSAURUS, Gibbes. Smithsonian Coutributious, 18ol, vol. II, p. 10. — Couosam-ops, Leidy, Proceedings of the Academy of Phil- adelphia, 1868, p. 202. CoNoSAURUs BOWMANii, Gibbes, Leidy, I. c. Greensand, No. "?, Burlington County, New Jersey. 277 PHASGANODUS, Loidy. Report of the United States Geological Smvcy of tlic Torritovies, I, 1873, 289. PlIASGANODUS DIRUS, Lcid}'. Proceediug8 of tlio Acailciiiy of Xaliinil Sciences, Pliiladelpliia, lf7, [i. 107 ; Report of llio Geological Survey of tlic> Territories, 1873, 1, p. 289, T.ilile XVII, fi}{8.23,24. From ("iiiiiioriball River, Dakota. PhASGANODUS gladiolus, Cope. I'latt- XLU, lij;. 11. Cimolichthys ijludioln^, Coiie, Proceedings of the American Philosophical Society, 1872, p. 353. Niobrara epocli of tlic Smoky Hill River. Piiasga.nodus ANCEPS, Cope, riate XLII, lig. 2. Cimolkhthys anceps, Cope, Proceedings of tbo American Philosophical Society, 1872, p. 352. Niobrara epoch of the Smoky Hill River. Phasganodus carinatus, Cope. Sphi/rana carinata, Cope, Ilaydeu'-s Annual Report, ly70, p. i2i. Niobrara epoch of Kansas. Phasganodus semistriatus, Marsh. Eiifhodus scmintrialus, Marsh, Proceeding.^ of the Aiiu'riean Association for the Advancement of Science, 1870, 'J3U. Greensaiul of No. 4, New Jersey. TETHEODUS, Cope. Haydou's Bulletin of the United States Geological Survey of the Territories, No. 2, 1874, p. 13. Tetiieodus PEPIIREDO, Cope, /. c. Plate LIV, figs. 1-3. Niobrara grou|) of Kansas. ENCHODUS, Agassiz Poissons fossilcs, V. Enchouus keuox, ]\Iortoii, Leidy. Proceedings of tlio Academy of I'liihulelpliia, 18.').'i, p. 3!I7. Below greensaiid, No. 5, New Jensey. Enchodus pressiden.s, Cope. Proceedings of the American Pliilosophical Society, 18Gf», p. "ill. Greeiisand, No. ?, of New Jersev. 278 Enchodus PK'IROSUS, Cope. Plate LIV, ligs. -4,5. Ilayikni's liiilletin of the United States Geological Survey of tbo Territories, No. 2, [i. 44. Niobrara group ol' Kansas. F^NCHODlis DOLICHUS, Copc. Plate LIV, fig. 7. Supra, p. '.^40. Niobrara Cretaceous of Kansas Enchodus oxytomus, Cope, sj). i/ov. Represented by one of the long teeth from the antei'ior exlremity ol' the preuiaxillary or dentary bones. It differs from other species of the genus in the extent to which the posterior cutting-edge is prolonged downward toward the base of the tooth, nearly equaling in this respect the anterior edge. As in all other Endiodl, the cutting-edges are not opposite, and a section of the base is unsynnnetrical. Cemenluni mostly smooth. Crown ratlier broad for its length, which is below the average of the Cretaceous species. Clays below Cretaceous, No. 4, New Jersey. Enchodus XEiKiEcus, Cope, sp. nor. Established on various teeth from the greensand of Delaware and New Jersey. The elongate anterior (eeth are narrow and slender; the greatest diameter at the base being at right angles to that of the u])per part of the crown. The posterior side is, as usual, mucii more convex than the anterior, and the two faces are separated by cutting-edges, both of which extend to the base of the crown. A shallow groove runs just behind each cutting-edge to the base, giving the latter an unsymmctrical fignre-8-form of section. Tiie anterior face is but little convex, and is perfectly smooth ; the jsosterior is very convex, and is marked with sharply defined grooves, about half-way to the ajx'x from the l^ase, i)ctvveen the lateral shallow grooves. Fifteen may be counted I'rom side to side. Length of crown, 0"'.030; median diameter, 0".005; l>asal diameter, 0"'.007. Cretaceous, No. 4, Delaware and New Jersey. Enchodus calliodon. Cope. /,. <■ , ]). :!r,4. \ Niobrara epoeh ot the Smoky Hill IJiver. 27U Enchodus suumakuii, Lcidv. Proceedings of tlic AcaJciiiy of Natiinil SciciicTS, riiilaclfl|)liiii, ISSCi, 'ifiT ; Hepoit, of tlio United States Geological Survey of the Tenitories, I, 1871!, 'iStt, Tabic XVII, fig. 20. Sage Crci.'k, Dakota. p:mp(), Copo. Proceedings of the American I'liilusoiiliical Society, 1^72, ]>. 'i47.—('inttjli!. Niobrara eptjcli of the Smoky Hill region, and of Trego and Rooks Counties, Kansas. Empo contracta, Cope. Plate LIII, fig.s. 14-17. HayiU^u's Bulletin of the United States Geological Survey of the Territories, No. 2, 187'!, p. -Ifi. Niobrara Cretaceous of Kansas. Empo merkillii, Cope. Plate LIII, figs. 10-13. Jhhl, p. 4li. Niolirnra Cretaceous of Kansas. STRATODUS, Cope. Proceedings of the AuuTican Philosophical Society, 1872, p. 348. StraTOUUs Al'lCALIS, Copc. Plate XLIX, ligs. (J-8. r.. (.,p.:!i',i. Nioljnira cpocdi of tlie Smoky Hill River. APSOPELIX, Cope. Ilaydcn's Annual Report, l-i7(), p. 4.;:!. ApSOPELIX SAUKIFORMIS, Cope. Plate XLII. lig. 4. L. c, 1870, 424. Rciitnii cpocli ;if lUmker Hill, Kansas. 280 HAPLOMI. ISCHYRHIZA, Leidy. Proceedings of tbi; Academy of Philadelphia, 1650,221 ; Cope, Proceedings of the American Philosopliical Society, 1872, 354. One species of this genus is not rare in the New Jersey greensaud; and a second one has been described from North Carolina, which may be ot" Mio- cene age, or be Cretaceous, but intrusive in Miocene beds. In any case, this or an allied genus is abundant in the Miocene of Maryland ; but the teeth of the species have not yet been obtained. The form, as I have already pointed out, is allied to tlie living Esox, but is referable to a distinct family (the Ischy- rhizidce), based on the coossification of many of the terminal caudal vertebral centra and spines into a fan-shaped body of considerable strength. IscHYRHiZA MiRA, Leidy. L. c, i>. 221. Greensand, No. 5, New Jersey, near Harrisonville. IscHYEHiZA ^NTiQUA, Leidy. L. (.:, 1656, p. 256 ; Emmous, Geological Survey of North Carol iua, 1856, figs. 47-46. ? Cretaceous of Neuse River, North Carolina. PYCNODONTES. PYCNODUS, Agassiz. Poissous fossiles, 16:53, I, p. 10 ; II, p. 163. Pycnodus faba, Leidy. Report of the United States Geological Survey of the Territories, 4to, I, p. 292, Plate XIX, iig. 16. Greensand, No. '?, of New Jersey. Incertce secHs. POLYGONODON, Leidy. PoLYGONODON VETUs, Leidy. Proceedings of the Academy of Philadelphia, 1656,221 ; Cretaceous Reptiles of the United States, 118, Plato IX, figs. 12-13. Greensand of Burlington County, New Jersey. 281 HOLUCEPHALI. LEPTOMYLUS, Cope. Proceedings of tbo Boston Society of Natural History, 1B69, i>. 'M'l. Three species of this genus arc known (o the writer, wliicli may 1)0 distinguished as follows: I. Mandible without apical dentinal cylinder: Large, massive, and not compressed L. datsus. 11. A terminal or apical cylinder: Outer margin much elevated; inner much depressed; large.. L. forfcx Outer margin less elevated ; the inner equally so ; smaller. . . L. cookii. Leptomylus densus. Cope. Proceedings of the Boston Society of Natural History, 1869, p. 313. Greensand of New Jersey, No. 5 ; Birmingham, Judson Gaskill. Lbptomylus forfex, Cope, sp. nov. This chimseroid is represented by two mandibles from distant localities, and probably by a maxillary bone. The form of these elements is highly characteristic. The mandible is much elevated; but the elevation is confined to the outer side, which rises as a lamina, causing the masticating face to be nearly vertical for much of its length ; but a short extent is level to the apex. There is a slight marginal swelling where the anterior outer dentinal area should be, and an abrupt rise in the margin to the position occupied in Lchyodus by the posterior outer area. The inner border of the masticating surface is parallel to the inferior border of the jaw, except where the two converge to the apex; here the entire face included between them is occupied by the large syinphyseal facet. The inner dentinal area is represented by a narrow acuminate patch on the inner angle of the masticatory face, ojiposite the tuberosity which represents the anterior outer. The apical aTea is very narrow, and extends for some distance along tlie. exterior angle ot the superior face. Mcilsilitiiuiits. M. Lenj^th of a fragment .' •>. 1.5|j Lengtli to tbo posterior outer tuberosity ^- '^*^' Depth bebind ^■'^'^~ Deptli at tbe anterior outer tuberosity 0. Ooa Dii>tli of tbo inner face behind 0. O.U Lin^th of the innor dentinal area 0.014 Width at tbo inner angle (behind) 0. 02.> Width near tbe 8ni)eriiir border n. 01.> 3(j u 282 The maxillary was found in connection with mandibles of Ischyodus mirificus, but does not pertain to them, and is only inferentially referred to this species. The resemblance to the mandibles is very great. Its oblique superior and outer face is greatly extended, while the inner is narrow and vertical. The usual superior groove is present, and close to the edge of the latter. The inferior border is quite thin. There are only two dentinal areas present, and these are exceedingly small, representing the outer and anterior inner of the species o{ Ischyodm. Length, 0™.140; width, 0'".024; depth (oblique), 0'°.070. This species is readily distinguished from its congeners. From the greensand of New Jersey, No. 5 ; a mandible from Horners- town, from Joliu C. Miers, and mandible and maxillary from near Barnes- borough, from I. C. Voorhees. Leptomylus cookii. Cope. Proceedings of the Aiuericau Philosophical Society, 1870, \i. :!84. Grreensand of New Jersey, No, 5, near Mount Holly, Burlingtim County. EUMYLODUS, Leidy. EuMYLODUS LAQUEATUS, Leidy. Re(iort of the Uuited States^Geological Survey, by F. V. Haydeu, vol. I, p. ;!0i), Plates XIX and XXXVII. Cretaceous, near Columbus, Northern Mississippi. BRYACTINUS, Cope, genus novum. Represented by a bone of the jaws, either mandibular or premaxillary. It resembles, in several respects, the Eumylodus Inquealus, Leidy ; but diifers in having several dentinal areas exposed along the outer margin, and in having the apical tube exposed at both extremities. From Ischyodus, it differs in the same respects and the excavation of the posterior half of the inner face. BkYACTINUS AMORPIIUS, CopC. The section of the jaw is triangular; the base representing the grimling- face, and not level, but, like both the others, slightly convex. The opposite angular ridge only extends half (he length of the jaw, and then sinks, and exposes the posterior end of (lie a|)ical column of dentine. Three other 283 columns issue on the ifiiiuliiig-face along the oiite\()nd. The anterior liordcr of (lie inner area is liroad and ol)luse. 284 Measurcmcntn. M. Length of tho fragmeut 0. 094 Leugth to the outer area U. 031 Length to the inner area 0. 041 Width of the inner area 0. 029 Width at the inner area 0. 038 Width of the outer area 0. 004 Greensand of New Jersey, No. 5. ISCHYODUS, Egertoii. The species of this genus are numerous in the greensuud of New Jersey, but have not yet been met with elsewhere in North America. One occurs in the Eocene formation of the same State, which is nearly allied to the Cretaceous forms. The species may be distinguished as follows : I. Dentinal areas very small ; the inner represented by two columns, widely separated from each other: Form compressed ; grinding-face vertical be- hind . - - . — /. denobryus. II. Dentinal areas moderate; the inner represented by three adjacent areas : Inner area inside of margin ; outer margin with tuberosities /. tripartitus. III. Inner dentinal area undivided : A Inner area contracted, and separated by a plane from the inner margin : Anterior outer on a prominent ledge 1. longirostrvi. AA. Inner area extending to inner margin of superior face of mandible : B. The anterior outer area produced anterior to the inner area : External areas on laminar crests of the border ; posterior area very small ; anterior cresi produced . /. ((deiigerm;. Each of the outer areas produced, and standing on a horizontal step of the thin outer margin . . - /. smoc/eii. 285 Antenor outer within the border, oval, on a hiifli tuberosity; beak long, narrow ; max- illary areas large /. eoccmus. Anffrior outer oval, standing on a high tube- rosity ; maxillary areas small ; beak nar- row / mn)iolo]>hiis. Anterior outer oval, much within the border, on a low tuberosity; beak thick, long . /. nicrassnfus. Anterior outer oval, not on a tuberosity ; pos- terior outer minute /. snxkiUii. l^B. Anterior outer area not produced anterior to the border of" the inner area : Anterior outer moderate, (m a prominent angle of" outer margin; inner margin al)ruptly excavated from inner area, which is wide. /. frcmuliis. \\\\q\-wx outer area not standing on an angle: inner border not abi'uptly excavated; inner area narrowed, not produced beyond ante- rior outer /. mmjinis. Anterior outer area not on a projection, not ex- tending as far as inner, which is narrow ; beak long, straight /. miersii. Exterior areas very small, the anterior not on an elevation ; beak not excavated, but turned outward ; inner area very wide /. divaricatus. IsCinODUS STENOBRYUS, Cope. Indicated by both rami of the mandibular arch. The characters are striking. The outer border rises rapidly from a little behind the apex, first to a shoulder, which supports the first exterior dentinal area, and then steeply to an oblique border, which bears the posterior area. The inner masticatory margin remains parallel with the inferior border of the jaw, marking one- third the total depth. The external areas are very narrow, and behind the anttn-ior a smaller one appears in the position of the inner one of /. Iripar- titus, thus representing the outer part of the large inner area. The inner part of this area appears on the inner edge, far removed from the former, is 286 iiiirrow, and cxiciuls n Hi lie anterior to the anterior liordcr of the anterior outer The apex oi' the jaw is obtuse, and the terminal area is on its superior aspect, is oval, and continues as the edge of a lamina along the outer margin of the beak. There is no syraphyseal plane, and the whole jaw is much compressed and narrowed. It has much the form of that of Lepfo- mylus forfex, and approaches the /. lafciigenis. Measurements, . M. Loiigth of tbo fragment (total) 0. 070 Depth behind 0.080 Depth at the posterior outer area 0. ()(>4 Depth at the anterior outer area 0. 04 1 Deptli at the inner area 0. OH Depth of the inner face behintl 0.027 Width at the inner area 0.018 Width behind at the inner angle 0. 021 Width l>ebind near the snmniit i'. 1)1.5 Hornerstown, New Jersey. Greensand ot No. h. ISCIIYODUS TRIPARTITU.-i, Cope. /. mirificiis, "Leidy," Cope, Proceedings of the Boston Society of Natural History, 18G9, p. 314, not of Leidy. This species was embraced in the specimens mentioned l>y Professor Leidy as having furnished the type of iiis 1. 7nirificus; and, as his tirst descrip- tion does not specify to whicli of them he referred, I had supposed tliat those belonging to the present species were the ones described. As Dr. Leidy has subsequently selected a different one as his type (in Report of Hayden's United States Geological Survey), it remains to give the present ChimaM-oid a new appellation. The /. tripnrtUus is the largest of the American species of the genus, and is not uncommon in the greensand of No. 5. The tripartite division of th(^ imier area is a prominent feature : tiic three columns are united at their adjacent borders: and tiie outer is more than twice as large as either of the two interior ones. The latter are separated froui the inner angle of the jaw l)y an ol)liqnc plane of some width, a character whicli is only seen in (lie /. longirostris among the other species of this genus known to me. The exter- nal areas are narrow; tlic posterior quite small. Tin; anterior is elongate, and extends far in advance of the inner areas along the summit of a horizontal ridge, which is produced as a strong step of the outer margin. The outer 287 narrow border rises abruptly opposite the middle of the anterior area, causing the masticatory face to be very oblique at that point. The outer face of" the jaw exhibits two longitudinal convexities, and the inner is nearly vertical, and with a short symphyseal plane. The beak is narrow and produced. The maxillary bones which accompanied the type-specimens are of usual charac- ter. The dentinal areas are large, and the anterior border not much pro- Greensand of New Jersey, No. 5. From the marl-pits of Judson Gaskill, at Birmingham, a locality which, through the interested care of the proprietor, has yielded many important additions to paleontology. ISCHYODUS FRCUNDUS, Cope. A large species, second in the genus to the / tripartitus. Both the inner and anterior outer dentinal areas are narrowed anteriorly, and they terminate on the same transverse line. The anterior outer is rather small and wide, and is horizontal, so that the apex is elevated abruptly above the outer border of the beak ; but not to the same extent as is seen in /. smockii, nor are the outer areas elongate, as in that species. The present fish is also twice as large. The inner border of the beak has the same abrupt descent as the outer. This form distinguishes it from /. mirificus. The posterior outer area is rather small, while the inner is large. The long axis is strongly curved, and the 291 outer side concave in vertical as well as transverse section. The inner face is also concave, with narrow symphyseal plane along inner border. The apical column is an oblique lamina. The maxillaries are narrowed and trun- cate in front ; the areas are large, especially the posterior. The superior groove is deep, and the outer face extensive and longitudinally ridged. A specimen from Medford, New Jersey, resembles the others, but is only half the size. Measurements. ii. Total length ; 0.135 Depth at the posterior outer area 0. 0.'iS Depth at the anterior outer area 0. 040 Depth at the middle of the beak 0.023 Width behind at the inner angle 0. O'M Width at the anterior outer area 0. 030 Width at the middle of the beak 0.020 Length of the maxillary 0. 110 Width at the apes 0.017 Width at the posterior edge of the posterior area 0.042 Depth of the outer face of the maxillary 0. 042 Eight lower jaws of this Chimseroid are before me, several of them accom- panied by maxillary bones. The eighth is, as before mentioned, from Medford, New Jersey. The others are from the same horizon, greensand of Creta- ceous, No. 5, from Birmingham and Hornerstown. IscHYODUS MiEiPicus, Leidy. Edaplwdon mirificus, Leidy, Proceedings of the Academy of Philadelphia, 1856, p. 221 ; Report of the United States Geological Survey, Hayden, I, p. 306, Plate XXXVII, figs. 1-6. Six lower jaws of this species, several of them accompanied by maxilla- ries, resemble closely the one described and figured by Leidy, as above. As Leidy represents, the inner, and especially the outer, borders of the beak are not abruptly excavated from the extremities of the dentinal area, but form a line generally uninterrupted. The anterior outer area is not supported on a tuberosity or angle, and is situated well inside the outer border. One speci- men includes all the pieces of the jaws. The premaxiUaries are entire. The median and outer borders are thickened, the latter most so ; while the inner concave face is excavated to a horizontal border of a basal thickening that extends from one edge to the other. The marginal dentinal areas are eight ill number, the inner and outer larger than the intervening ones. The specimens in my possession are from near Barnesborough and Hor- nerstown, New Jersey ; greensand, No. 5. 292 ISCHYODUS MIEESII. ? Dipriatis miersii, Jlarsh, Prooeediugs of the American Asaociation for the Advancement of Science, 1870, p. 230. The mandible of this species is peculiar in several respects. The beak is long and straight, and the outer face is concave to the base of the anterior outer dentinal area. The anterior outer dentinal area is not elevated above the grinding-face in front of it, and is near the edge of the iavv. The inner area is acuminate, and produced beyond it, and extends to the inner border. The inner face is slightly concave, with a broad symphyseal bevel along the inner margin. The apical area is the end of a curved laminar column The long axis of the jaw is straight, as is the inferior border, differing from allied species, which are more or less curved. Lower border transversely thickened. Measurements. M. Length of the fragment 0. 100 Length to the anterior onter area 0. 005 Depth at the anterior onter area 0. 030 Width at tlio anterior onter are.a 0. 02'i Width of tlic middle of the beak 0.015 Depth at the middle of the beak 0. 015 Diameter of the lower border at the middle of the beak 0. 017 A broken maxillary and a dorsal spine accompany this mandible. The latter is identical with the ichthyodorulite described by Marsh, as above, as D'quistls miersii. My specimens are from the locality from which the latter was derived, viz, the excavations on the property of John G. Miers, at Hor- nerstown, Monmouth County, New Jersey. IsCHYODUS DIVARICATUS, Cope. Proceedings of tlie Boston Society of Natnr.al History, 1869, p. 315. Besides the typical specimen, three others have come into my hands. They exhibit the general peculiarities, as the uninterrupted masticatory sur- face, the small external areae, the anterior subround, and opposite or behind the apex of the very large inner; the narroved beak making an angle with the posterior part of the jaw, and penetrated l)y a laminar column of little width. Size rather less than that of / fecundus. New Jersey greensand, No. ,'i, from near Hornerstown. 293 MYL0GNATHU8, Leidy Proceediugs of the Academy of Philadelphia, 185G, 312. Mylognathus priscus, Leidy. Proceedings of the Academy of Philadelphia, 1856, 312 ; Transactions of the American Philo- sophical Society, 1860, Plate. Fort Union Cretaceous of Long Lake, Nebraska. ISOTiENIA, Cope. Established on a maxillary bone, which differs from that of Ischyodus in wanting the superior groove. Two dentinal columns are exposed, which rep- resent the anterior two of that genus ; but they differ in being on the same plane, and hence issuing on the masticatory face together, being only sepa- rated by a narrow partition. Whether the other column is present is not ascertainable, as the lower part of the bone is removed. IS0T.^NIA NEOCESARIENSIS, Cope. The solid planes of the maxillary bone of this species are three ; the widest is opposite to the dentinal columns and parallel with them ; it is nearly as wide as they. The lateral planes are not parallel with each other : the wider forms an acute angle with the last described; the narrower, a very obtuse angle, so as to be nearly continuous with the same, running out into it posteriorly. The more vertical side retains the same depth throughout. One end of the bone is rounded and truncate; the other is excavated directly at right angles to the dentinal areee, and then continued as an edentulous plate, which is soon broken off in the specimen. Measurements. Total length ^-"^^ Length of the dentinal columns "• "^^ Width of the dentinal columns ^.Va^ Depth on the vertical side 0. 020 Greensaiid of New Jersey, No. 5, at Hornerstown ; John G. Miers. SPHACEPCEA, Cope. Proceedings of the American Philosophical Society, 1869, p. 241. SlMIAGEPCEA ACICULATA, Cope, /. C. Greensand of No 5, Birmingham, New Jersey. 294 ELASMOBRANCHIL PTYCHODUS, Agassiz. Pi)issou8 tbssiles, 18:i3, III, 150. Ptychodus polygyeus, Agassiz. ■Poissons fossiles, III, p. 150 : Gibbcs, Jdunial of tbu Acadi'iny of Philadelphia, 1849, 299, Plate XLII, figs. 5-6 ; Leidy, Proceedings of the Academy of Philadelphia, 1868, p. 208. Rotten limestone of Alabama, and Niobrara epoch of Kansas. Ptychodus janevah, Cope. /Spoceforfiis jo»f!)oi). Cope, Hayden's BuUetiu of the United States Geological Survey of the Territories, No. 2, 1874, p. 47. Niobrara Cretaceous of Kansas. Ptychodus occidentalis, Leidy. Proceedings of the Academy of Philadelphia, 1868, p. '207 ; Report of the United St.ate8 Geo- logical Survey of the Territories, 187;{, p. 398, Table XVII, 7-8, XVIII, 15-18. Niobrara epoch of the Smoky Hill. Ptychodus mortonii, Agassiz. Poissons fossiles, 111, p. 158, Plate 25, figs. 1-3. Niobrara Cretaceous of the Smoky Hill River, Professor Mudge ; Ala- bama ; Mississippi. Ptychodus whippleyi, Marcou. Geology of North America, 1858, p. 33 ; Leidy, Report, etc., 1873, 300, Table XVIII, 19-20. Niobrara epoch of the Arkansas River, Kaiistis ; also, Colorado and Galisteo, New Mexico. Professor Merrill. Ptychodus mammili,aris, Agassiz. Poissons fossiles, III, p. 151. Cretaceous greensand, No. 4, of Delaware. Ptychodus papillosus, Cope. The grinders of this species possess the elevated form of those of P. ivhi2)pleAji, and are of about the same size. The surface is characterized by the absence of folds or ridges, but is uniformly covered with subequal areolae or papilloB of small size, giving the cementum a shagreened appearance. Cretaceous, No. 3, of Colorado, east of the Rocky Mountains. 295 GALEOCERDO, M. & H. Affussiz, PoisBous Ibssiles. GiLEOCERDO CRASSIDENS, Cope. Proceedings of tlid Aiiiericau Pliilo.sopliicul Society, 1872, p. 355. Nfobraia epoch of the Stiioky Hill. Galeoceruo hartveleii, Cope. L. c, 187-2, :i5(i. Niobrara epoch of tiie Smoky Hill. Galeocerdo falcatus, Agussiz. Lei. HOV. This turtle is represented by bones of the cranium and of tlie carapace ; the former including mandibular, maxillary, frontal, sphenoid, and quadrate bones ; tlie latter, two lateral marginals. The dentary bone is stouter, but not so large as in T. latiremis, Cope, and is flattened concave on its superior alveolar face, whose outer border, though sharp, is not elevated above the level of the inner border. The symphysis is short, and there is no beak. The inner face of the dentary is a broad, shallow groove. The head has evidently been short and wide. The poste- rior part of the maxillaries only are preserved. The alveolar face is flat, and the outer border is produced vertically to a sharp edge. There is a suture for a malar bone, and the orbit was evidently large. The frontal bones have an open median groove below. The interorbital space is nearly flat, and the or1:)ital borders subparallel for a short distance. The prefrontals are stout, extend to tlie middle of the superciliary border, and are united on the median line in front. The free border of the parietal on one side, though not well preserved, indicates tliat the temporal fossa is partially roofed, as in Chelijdra. The quadrate is remarkaijly solid, and is distinguished by the open or fissure- like form of the meatus auditorius, which is a consequence of the shortness of the posterior hook, which is not produced into contact with the lower part of the body of the bone. The concavity of the upper part of it is very shal- low ; its outline is subtriangular, with a flat superior border ; there is no trace of the buUa-like superior chamber of Chelijdra. The body of the bone is wide and slightly concave above, the anterior face separated from the supe- rior by an overhanging angle, and also concave. The condyle of it is quite small and flat; a larger, apparently articular, face is adjacent to it on the posterior face. The sphenoid bone is wide and flat. 299 300 The two marginal bone's are longer than wide and quite thin. The proximal margin is obtuse, rugose, and but little thickened, and exhibits near the end in each bone a small oval fossa for the extremity of the rib. The external margin is thin and sharp, and is produced into a prominent angle near the middle in each bone. This presents a right angle partially backward, and is thin-edged. The bone is dense, and there are no indications of scutal sutures. Ileasiirements. M. Leugth of the dentary bone 0 048 Width above 0.009 Depth ou the inner side at the middle 0.007 Width of the maxillary O.OU Depth of the maxillary on the outer side 0. 008 lutcrorbital width 0.016 Width of the sphenoid at the middle 0.016 Antero-posterior width of the quadrate above 0. 016 Depth of the quadrate externally 0. 021 Length of a marginal 0. 048 Width of a marginal 0.033 Depth of a marginal proximally 0. 006 The characters displayed by this species ally it to the genera of the New Jersey greensand, as Osteopygis, etc., which, as I have pointed out, possess characters of both the Chelydridce. and the CheloniidcE. The super- ciliary border of the frontal, with the extent of the prefrontals, with the indi- cations of a short temporal roof, are characters of Chelydra. The absence of dermal scutal sutures distinguishes the genus from Catapleura, Osteopygis, etc. The stouter and deeper dentary bone strongly distinguishes the species from Toxochelys latiremis, Cope (see p. 98). PISCES. Enchodu.s dolichus. Cope, supra, p. 239. Several additional specimens of this fish exhibit the following charac- ters: No. 1 shows that the long premaxillary tooth has a cutting-edge on the posterior side of the apex extending one-fourth the length, and directly oppo- site the anterior edge. The surface of this and of the maxillary teeth is not sulcate, but striate, and with a silky luster. The maxillary teeth, as in other species, diminish in size posteriorly, and display two cutting-edges nearly to the base. In No. 2, the dentary bones of both sides are preserved. These display a series of small, acute teeth on the outer alveolar margin, which passes round the outer side of tiie larger anterior flings to the end of thi' 301 symphysis. There are coarser strire mingled with the finer ones on the posterior faces of the mandibular teeth. Rami slender. This specimen exhibits the mode of succession of the teeth, which is quite peculiar and different from what I have described in the other genera. The first teeth appear on the alveolar surface at a considerable distance apart. The second teeth appear immediately in front of these, and by their presence create the irritation whicli results in the alssorption of the root and shedding of the crown of the first. The teeth of the third series appear in advance of tlie second, occupying the space between them and the empty space previously occupied by No. 1. These may co-exis,t for some time with teeth No. 2, as the specimen indicates, but the result is as before, the shed- ding of the adjacent older teeth. In the case of the anterior long tooth of each side, the movement is reversed. Here the successional tooth appears l)ehind the position of the functional, which is consequently shed, and in the old fish this tooth occupies a position behind a concave symphyseal portion, which is concave and edentulous, or only provided with the small teetii of the marginal row. Tlie skull of this species is flat, and the frontal bones are very thin. They are strengthened by a longitudinal striate rib on each side, which passes from the posterior jwrt of the cranium to tlie prefrontal region. There are apparently no exoccipital condyles, and the basis cranii is simple and with a short keel on the basioccipital. A comparison of this species with a new specimen of the Enchodus gladiolus, Cope {Phasganodus m.), better than that previously described (see p. 235), exhibits the following specific differences. (The latter species was founded on a long anterior maxillary tooth.) The teeth all differ in possessing on the posterior face a sculpture of parallel grooves. The known s|)ecimens are larger. In the E. calliodon, the grooves ai'e fewer and stronger, and the cutting-edges of the fangs are not opposite. The specimens above described indicate that the genus Phasganodus, Leidy, as defined in the present work, is untenable, and that the species must be united with Enchodus ; the greater or less convexity of the sides of the fangs offering specific characters only. The Enchodus anceps (Phasgano- dus, 1. c.) differs from the two species above described in the shorter and much stouter teeth. Its long fangs are not certainly known. 302 RKCAPITULATION. AVES: Species. Natatores 3 Gralla. 4 Saururce - - - 2 Reptilia : Dinosauria ,.......,. 18 Pterosauria - , - 4 Crocodllia - - 14 Sauropterygia ..,.., 13 Testudinata , 48 Pythonomorplia . . ,,..,,,.,.,,... 50 Pisces : Percomorphi - . . , - 1 Percespces . - 2 Isospondyli _ - 43 Haplomi - 2 Pycnodontea 1 Actinochiri 3 Holocephali 23 Elasmobranchii 22 147 97 Total vertebrata 253 I^DEX Actiuochiri, 244 A. Adocus, 91. liiieolatus, 92. Agathaumas, .^8. sylvestio, 31, 34, 53. Anogniins, 240. Apsopt'Hx, 241. sanvifoi'iiiis, 17,242. Bervx, 22. Bottosaurus, 68. peri'ugosns, 08. Bryactiims,282. amoiphiis, 282. C'ioiiodoii, .'■)7. aictatus, 60. stenopsis, 63. Clastes, 28. Clidastes, 130. eiueiiarmii, 137. plaiiifions, 13:"). stenops, 133. tortor, 48, 131. Compserays, 91. ogniiii8,91. Croco(lilia,67. Cucullifera, 24. eccentiica, 24. Cynocercus, 9li. inciisus, 96. DaptiDns,213. plilebotonms, 213. Diuosamia, 28, 29, 53. Diphrissa, 283. latidens,283. Elasiiiosanrus, 75. platyiiriis, 44,79. Empo contiacta,232. merriUii,232. nepiEolica, 230. seuiianceps, 18,233. Encbodus, 23, 238. calliodou,240. dolichiis, 239, 300. oxytoniiis, 278. petrosus, 239. tetiiBCiis, 278. Erisiehthe, 23, 217. nitida, 217. Galeocerdo, 243. crassideus, 243. hart vcUii, 244. Gavialis, 254. fraterculus, 254. Hadrosaurns, 56. mirabilis, 56. occideutalis,56. Haploscapha, 23. eccentiica, 24. grandis, 23. Holops, 250. Holops, pneuiiiatieus, 250. Hyposaurus, 67. vebbii, 17,67. Ichtliyodectes, 23, 205. auaides, 206. cteDodon,207. liamatiis, 209. ruultideutiitus, 212. proguathus, 210. Ischyodus, 284. divaricatus, 292. eocteuus, 288. fecundus, 290. gaskillii, 290. iucrassatus, 280._ laterigerus, 288.' lougii'ostris, 287. mier8ii,292. uiirificus, 291. mouolophns, 289. sraockii,288. steuobryus, 285. tripartitua, 286. Ischyrbiza, 280. IsotfEuia, 293. neociBsaiiensis, 293. Laniua, 296. texaiia, 296. macrorhiza, 297. nuidgei,297. Leptomylus, 281. forfex, 281. Liodon, 160. dyspelor, 46, 167. mitcbillii,270. nepseoliciis, 177. prorjger, 18, 46, 161. Ornithosauria, 65. Osteopygis, 257. erosua, 258. Otodus, 295. divaricatus, 295. Oxyrbiua, 296. Pacbyrhizodiis, 23, 220. caniiHi9,221. kingii,223. latimeutnii],223. leptopsis, 225. slieareri,225. Pelecopterns cbirnrgus, 244 D. gladias,244E. perniciosus. 244 E. Pelecorapis, 182. variiis, 16, 182. Percesoces, 180. Phasgauodus, 235. anceps, 236. carinatiis, 235. gladioluH, 235. Pisces, 179. Plastomeuus, 27, 28, 92. coalesceiis, 93. costatus, 94. insiguis, 95. piiuctulatiis, 94. Platecarpus, 141. corypbiuus, 47, 142. crassartiis, 153. curtiro.stri8, 150. glaudiferns, 18, 156. ictericus, 144. latispinis, 155. mndgei, 157. tectulus, 159. Plesiosaiirus, 88. brevifemur, 256. gulo, 88. Polycotylus, 70. latipiunis, 45, 72. Polyouax,'63. mortuarius, 64. Portbeus, 23, 190, 273. arciiatiis, 204. ]e9trio,201. mollosus, 50, 194. inudgei,204. tbaumas, 196. Protostega, 99. gigas, 48, 102. Pterodactylus, 65. umbrosus, 48, 65. occidentaiis, 66. Ptychodus, 244. jauevaii,244. papillosus, 294. PythoDomorpba, 45, 113,264. Eeptilia, 51. Saumcephalus, 215. arapabovius, 216. lanciformis, 216. Saurodontidfe, 183. Sauroptetygia, 29, 69. Selachii,243. Sirouectes, 139. auguliferus, 139. Str-atodoatidaj, 218. Stratodus, 226. apicalis, 227. SylL-eiiuis, 180. latifrons, 181. Testudinata, 90. Tetbfodus, 237. IJepbiedo, 2.37. Toxocbelys, 98. latiremis, 98. serrifer, 299. Trionyx, 95. vagans, 96. EXPLANATIONS OF PLATES EXPLANATION OF PLATE I. Boues of Cionodon arctatus, oue-half natural size. Fig. 1. Right maxillary bone with tcctL : a, viewed from the inner side ; 6, from bulow ; c, from above ; d, from the proximal end. 2. Fragment of a cranial bone. 3. Dorsal vertebra, lateral view : a, same from before ; J, from below. 4. Dorsal vertebra, lateral view : a, from before ; h, from behind. 5. Caudal vertebra, from the side : a, from the end. G. Femur, distal end, antero-posterior view : a and c, lateral views ; &, end view. Il,f .(SfukigitslSimtfi) sfilic Eexrskrmz. Wim$ 1. Drawn ty E.G-Beaux. Ik" Sinclair i ion um.Pftila . GIONODON ARCTATUS. EXPLANATION OF PLATE IL Figs. 1-2. Cionodon arctatus, one-half natural size. Fig. 1. Proximal end of tibia from front : a, from outside ; 6, from inside ; c, from above. 2. Distal end of the tibia from the side : a, from below. Figs. 3-5. Vertebra) of Polyonax vwrtuarius, one-half natural size. Fig. 3. Anterior dorsal, articular face of centrum : a, side view of centrum. 4. Anterior dorsal, articular face of centrum : a, side, and b, lower face of the same. 5. Posterior dorsal or lumbar vertebra, side view of centrum : a, inferior view ; b, articular face. fl>$. 6c.oijJfllcalSvtr'tifv fffilw MnrAork^. MfXtc n. si^i-s^i;'*;.,?' ■ ■=<:«sii^>-_ 1 ,-:^ ...___^%j .^«»il< /:?*T- :^i'/-«f ;/ , :^i W'^J ■^«#p- ■^P^^ ' ^ ^Si.. a"* Sinclair & S^: 1-2. ClONODON ARCTATUS. 3-5. POLYONAX MORTUARIUS. EXPLANATION OF PLATE III. Figs. 1-4. Poljjonax mortuaiius, ono-balf natural size. Fig. 1. Fragment of femur from side : a, same from below ; h, from above. 2. Fragment of ?iscbium from side; a, narrower extremity; h, stouter extremity. 3. Broken fragment of the other I ischium, edge view, showing internal cavity. 4. Inside view of part of fibula: a, superior end view of the same. Figs. 5-6. Bones of lliulronaurvs t occidcutaJis, from Colorado. Fig. 5. Fonith sacral vertebra from the tide, one-half natural size : a, same from below ; b, from front. C. Fragment of head of tibia seen from above, four-tenths natural size. II, S, :6f 33L00ks3l^Mftifg rfilfc 'Ciccrtturks. inis 111 IflW S3n=iairiSoii.lith..Pl>ila. 1-4. POLYONAXMORTUARIUS. 5-6. HADR03AURUS, EXPLANA.TION OF PLATE IV. Agathaumas sylvestre, one-sixth natural size, except 19-20, which are ouc-foiirth the same. Figs. I-IO. A coutinuons series of dorsal, lumbar, ami sacral vertebrae, viewed from the right side; one only of the neural arches found in place. Fig. 2. Second vertebra of the series : a, viewed from behind. Fig. 7. Antepenultimate lumbar vertebra: o, viewed from before; d, viewed from behind. Figs. 10-lG, a. The sacral series viewed from above. 10-lG, b. The same viewed from below. Fig. 10, c. Proximal end of sacrum. 14, 0. Dis'al end of the fifth vertebra of tlie same. 16. Seventh sacral vertebra: c, anterior view; d, posterior view, both exhibiting the inferior posi- tion of the articular surface for the diapophysis. 17. A more distal sacral vertebra : b, from below. 18. The neural arches of two consecutive ? sf.cral vertebra;, coosified, and with diapophyses free from the centrum: a, from above. Figs. 19-20. Undetermined bones. Fig. 21. L.ater,al view of the acetabular portion of the ilium, with the base of the ischium continuous with it ; o, the same, viewed from below. \i, f. lAci'linitfalf Afrtuu rf"iJ).c Cf aitdrirs plcvtf :n AGATHAUlvLAS SYLVESTRE EXPLANATION OF PLATE V. Figs. 1-3. A3a/7iaH7)i«s s/zZctsd-e, three views of iliiiui, one-.sixtli uatuial size : a, the outer side; h, the iut'erior edge ; c, the iuneiside; the iliac acetabular face retains some of the luatri x ; see PI. IV. r'-i '^^L ire (S 4?^ \ ! 'I -\t h J «r-.- "\ '-^ mm) EXPLANATION OF PLATE VL Figs. 1-4. Agathaumas sylventre, one-fourth natural size. Fig. 1. A ? rib. Figs. 2-3. Undetermined bone8. Fig. 4. Neural arcb of a donsal vertebra minus the processes. Figs. 5-8. Bottoaauriis perrugosus, one-half natural size. Fig. 5. A posterior dorsal vertebra from front : a, from behind, and, h, from below. 6. Posterior part of mandibular ramus from outer side ; 6, from inner side. 7. Portion of deutary bone with alveoli : a, from inner side ; 6, from outer side. 8. Distal end of femur found with the preceding ; a, lateral view. Figs. 9-16. Fragments of tortoises from the Cretaceous of Colorado, natural size. Fig. 9. PlaKtonuiiHs pnnctidatus, costaXhone, 10. P. insiijnis, liyposternal bone. Figs. 11-12. Adocus liueolatus : 11, from plastron ; 12, vertebral bone. 13-14. Triouijx ragaiis, portious of costal bones. 15-16. Marginal bones of Compsemys victua. M,$.6wijjgit3i^Attirci; i^'Urc f etttorirs. lirdc '^1. * Sa-iiSir A bor. .rai. I'L-ia.. l-'i'.AGATHAUM-AS SYLVESTRE. 5-8. B OTTO SAURUS PERRUGOSUS. 9-lO.PLASTOMENUS. 11-12. ADOCUS. 13-14. TRIO NYX. 15-16. COMPSEMYS. EXPLANATION OF PLATE VII. Bones of OrnUlwsaurians and Sauroplerygians, oue-liall' natural size, excepting Figs. 3-4, which are natural size. Fig. 1. Wing-metacarpal of PIcrodacfi/his nmbrosus, Cope, from below. 2. Phalange of first rank of the same digit. 3. Lateral carpal of the same, natural size. 4. Phalange of clawed digit of same individu.al. 5. Wing-metacarpal of Ptcrodactijlus occideiilaUs, from below. (). First phalange of wing-finger of same, but doubtfully of the same iudividual. 7. I'olycotylus lalipimm, humerus from inner side ; 7 o, from edge. .;(Sf 0i09ttalJfitriir!is &ftkc Enr&mm. fllRtc TH. -4. PTERODACTYLUS UMBROSUS. 5-6. P.OCCIDENTALIS. 7. POLYCOTYLUS LATIPINNIS. Ji" Sinclair i Son litiv PMa. EXPLANATION OF PLATE VJIL Figs. 1-2. Toxochcli/s latiremis, oue-half natural size. Fig. 1. Mandible from above; 1 a, from outer side. 2. Coracoid bone. Figs. 3-5. Cynocercus inc'.stn, natural size. Fig. 3. A caudal vertebra, lateral view : a, inferior ; b, anterior ; and, c, posterior views. 4. Caudal vertebra, lateral view: a, view from below; 6, from front; <■, from beliind. Figs. 6-7. Plastomenus coalesceits, one-half uatural size : C, portion of caraiiaco from above; 6 a, same from below. Fig. 7. Portion of plastron with lateral free border, from below. 8. I'lastomenus coslatiis, costal bone, external surface ; a, same from below. 9. Caudal vertebra of a JIadrosauriis from Milk Kiver, British America, one half natural size; a, front view. M. $>.6.c.a:UigticaiA\raif|) M'lbr CctrJtprics. ifijtttTM. Thf Sinclair 4 Soil litk.PMla. 1-2, TOXOCHELYS LATJREMIS. 3-5. CYNOCERGUS INCISUS. 6^7. PLASTOMENUS COALESCENS. 8.P. C0STATUS.9. "^ HADROSAURUS. EXPLANATION OF PLATE IX. Boucs of Froioslega gUjas, oue-tliinl natural size. Figs. 1-3. Marginal bones : 1 a, lateral from above ; 2, another lateral from bel()\\ ; 2 a, the sanie from one end ; 3, ? caudal marginal. 4-7. Ribs ; 7, posterior. Fig. 8. Cervical vertebra of Jlyposaurus reibianus, two- thirds tbe natuial size : a, from (be side; h, f om the front ; c, from below ; d, from above. M,$.,(S.c0LogtcaLS.irftiry ffftlrs.* Cttnibmrijg. lUiic IX. -r V. 8t iA tJ'a % % / It- ^ ^^f 5 V". 8d J »= SmcJair k Son li-Uri. PMli: . 1-7. PROTOSTEGA GIGAS. 8. HYPOSAURUS "\^BBII. EXPLANATION OF PLATE X. Cranial bones oi rroioslcga gtgas, Cope, one-half natural size. Fig. 1. Maxillary boue : a, from without; b, from within. 2. Deutary bone : a, from witliout ; b, from within ; c, anterior view. H. Posterior portion of inanililiular rau)n.s from within : a, ileutary ; 6, articular; c, angular bones. 4. Posterior portiou of mandibular ramus from the outside ; letters the same. 0. Quadrate and pterygoid bones of the riglit side from within. 6. Quadrate boue of the same side from without. II, S,.(S:Ciii.irgicalSAffliru fffiJir Ccrrfe'rlfs. la -^-.j^:^ lb .<^. ^.V;a, PROTOSTEGA GIGAS. EXPLANATION OF PLATE XIL Bones o£ Piotostega gigas, one- 1 hi id natural size, except Fig. 1, which is oue-balf nature. Fig. 1. Neural arch of ? cervical vertebra, from above. 2. Left humerus. Figs. 3-4. Metapodial bones. Fig. 5. Scapulo-procoracoid of the rigbf- side. t'. Coracoid of the right side. Figs. 7-9. Phalanges. Fig. 10. Normal lateral marginal bone, from below. 11. Vertebral ? nuchal bone, from above. V2. Marginal bone with two lamina;: a, from without ; //, from the proximal or inner margin. 13. Long anterior marginal bone. -li,^. 6c.a logkalSiifrtiry irEHlr,cCrmfe>rir5. p&k xn. Ti" Sinclair i Son UUi Phila , PROTOSTEGA GIGAS. EXPLANATION OF PLATE XIIL Two dermal boucs of Protoslcga gigas, one-tbiiJ natural size. 11, !>>.($ fiikiHicrilSvrftifD iTFihi: Cftritotirs. phi-lt SHI. -^ ^* ■1^"' t s. ■■■i *n: U:^.^^*^. V^MJ --•'^x V ' Sinclair iSor..:itK.?Kua. PROTOSTEGA GIGAS. PLXPLANATION (^'^ PLATE XIV. Figures one-half uatnral size. Fig. 1. Cranium of Cliclastes tortor, side-view: eiul of dciitary bone wanting; mandible viewed fnim llie outer side. •2. Clidasles steiwju, right ramus of the mandible ; 2 ii, side-view of prefrontal bone. 3. Craninm of riatecarpus curtirostris, side-view : the mandible viewed from the inner sidi'. 4 Platecarpus ic/ericiis, right dentary bone from the outside; a, surangular bone from the inside; 6, inner view of fragment of left dentary bone ; c, proximal view of the fragment. -H>.0'-)niliiatf alSimi« «*"*>■• ft'rrimri??. |ilaU XIT. w ^^J^m CLIDASTES TORTOR. 2.CLIDASTES STENOPS 3 PLATECARPUS CURTIROSTRIS, 4.P1CTERICUS EXPLANATION OF PLATE XV. Occipital regions and suspensoria of rijilionomorpha, one-lialf natural size. Fio. 1. Plalecarpua conjphceus : a, from behind ; 1>, from before ; c, from below. 2. Platecarpus ictericiis : a, from bebind ; h, from below. 3, riatccarpvs curtirosMs : a, from bebind ; b, from in front ; c, from below. M,S. CSw^bgwaiSiiA^fw irftiic Cctr&riifs 1. PLATECARPUS CORYPHAEUS. 2. R ICTERICUS. 3. R CURTIROSTRIS. EXPLANATION OF PLATE XVL View (if crania, (if Piithonomorpha, from above, oiu-Iuilf natural size. Fig. 1. CUdaities lortor ; 6, preraaxillarj' boue, from below. 2. I'lutecnrpiis mndijci, frontal and parietal bones. 3. rUiicmrpiis coriipliwiii, frontal bone only. Figs. 4-5. Pluteearjius curliroslris : 4, frontal and parietal bones, from above; 5 premaxillary and adja- cent part of right maxillary bones, from left side and below. ^I,S. CScakigknlSvitnicD irfibc U.cfrtbjrirs. Plvilc :ct. ' Sinclair t Son iitK.PKila. 1&6. CLIDASTES TORTQR. 2-5. PLATE CARPUS SPECIES. EXPLANATION OF PLATE XVIL Superior cranial walls of Pylliouomorplia, from btlow aud above, one-half natural size. Fig. 1. CliOastes tortor, from below. 2. Platecarpus cnrtirostris, from below. 3. Plaiicarpus iclericiis, from below. 4. Platccarpus iciericus, from above. 5. Platccarpus mitdgei, from below. G. Platccarpus coryphaus, from below. 7. Clidastes stowps, from below, without prefrontal bone. 8. Clidastes stcnops, from aljove, with right prefrontal bone. :t.f .6riiUi.qwalfttrtu-i) st'-ilic (SmMm. Pln.-tc xvii. I.CLIDASTES TORTOR. 2,PLATECARPUS CURtirostris 3.^ p^^^gcARPUS iCTERICUS. 5.LI0D0N MUDGEI. 6. PLATECARPUS CORYPHAEUS. 7.9 CLIDASTES STENOPS. EXPLANATION OF PLATE XVIII. Vertebrae of Pythonomorpha of three species, all iiioro or less incomplete ; one-half natural size. Fig. 1. Column of Clidastes stenops, including some of the cervical, dorsal, lumbar, and caudal vertebrae ; side view, beginning with the axis. 2. The axis, from below. 3. Thiid cervical ; a, from below ; b, from behind ; o, from in front. 4. Fonrth cervical: a, from before; J, from behind ; c, free hypapophysis. 5. A dorsal vertebra : a, from above ; ft, from below. 6. Part of vertebral column of Plalecarpus ictericus, from the side; a dorsal vertebra from above. 7. Part of vertebral column of Platccarpus curtirostris. 8. The atlas of Platecarpus curlirostris : o, centrum ; 6, the neurapophysis from the front; c, from the inside ; d, from the outside. it , § . 6 c a Luattal Sitrli ru cHltc & rriti! ri rs Pin}jtx\'[[i, 1-5,GLIDASTES STENOPS_ 6, Plateqarpus ICTERICUS 7-8. PLATE CAHPiJ^ ^URtirqstris. EXPLANATION OF PLATE XIX. Vertebraj oi Pijthonomorplia : of CUdantes torlor and PJalccarpas icitriciis, ono-lialf natural size. Fi«. 1. CVidastcs torlor, atlas centrum. 2. Ditto, axis: a, from tlie side; 6, from liehiiid. 3. Third cervical vertebra: a, from beliiud ; h, from before; o, from below ; (I, from (be side. 4. Cervical more posterior: a, from below, showing free bypapopliysis attached and crushed; Zi, from behind. 5. Cervical vertebra liebind tte last figured, from behind ; «, from before. C. rost(^rior dorsal vertebra: a, from behind ; h, from in front; c, from below. 7. rialicarpus ic/(Tic«s, axis vertebra, from beliind. 8. Third vertebra : a, from behind ; b, from below. 9. A posterior cervical : a, from front ; ft, from below ; c, from behind. 10. Last cervical : a, from front; 6, from below. 11. Radius or fibula of a small CUilastes from Fossil Spring Canyon ; a, the inner edge of the same. H, f .difiukgkjjiSirfti-fg rfliri' fiftrtLpri^s. Piatt 2CK. Tl," ainclsdr i Sjn hm-.-PKiU ]-6. CLIDASTES TORTOR^ 7-10. PL ATE CARPUS ICTERICUS. U.CLIDASTES. EXPLANATION OF PLATE XX. Vertebra) of Fijthonomorplia, onc-lialf natural size : species, Platccarpus icterictts aud Platccarjms cori/pliaeus Fig. 1. riatccarpiis ictericiis, median dorsal vertebra : a, from behind ; h, from below ; c, from front. Figs. 2-3. Platccarpus ictericus, Inmb.ar vertebra : a, from behind ; b, from below. These vertebrie were found lying on their sides, and the form of the articular surfaces is slightly altered by pressure. Fig. 3. Posterior lumbar vertebra : a, from before ; fc, from below; c, from behind. 4. Platccarpus corypha'iis, axis and third vertebra: a, from the side; 6, from below; o, from behind. 5. Three cervical and two dorsal vertebra) : i,e, (?, and c, views from side, below, behind, and above, respectively ; g, h, i, k, and I, similar views of another ; m, n, side and front views of an ante- rior dorsal. G. A posterior cervical from behind. 7. Posterior dorsal vertebra : a, from below ; J>, from above. l{,S..6,f.okii|kalSAirri)ru rf:tl?.c ferrtetps. KlS XX. 1-3. PLATECARPUS ICTERICUS 4-7. P. CCRYPHAEUS. EXPLANATION OF PLATE XXI. Fig. 1. Posterior dorsal vertebra of Platecarpus coryplimis: a, from front; h, from behind. 2. Dorsal vertebra near the position of the last, from below. 3. Platecarpus , from below. 4. Anterior cervical vertebra ; 4 h, from below. 5. Cervical vertebra, more anterior; 6, centrum, from below, fi. Anterior dorsal vertebra, from front; o, from above. 7. Platecarpus ciirtirostris, one-half uatnral size; a, axis, from behind ; 6, from below. 8. Platecarpus curtirostris, third cervical: a, from front; b, from below: o, from behind: (f, from above. Figs. 9-11. Anterior dorsal vertebra* of the same species: a, views from front; V, from behind; c, from above. Fig. 12. Median dorsal, from the front. 13. Posterior dorsal: a, from front; h, from behind ; c, from below. 14. Clidastcs ciiieriarum, Cope, postero-median dorsal vertebra: a, from front; 4, from behind; c, from below ; d, from the side. 15. Lumbar vertebra : a, from the side; I), from behind; c, from below ; d, from above. 16. Anterior ciudal vertebra : o, from front ; 6, from side. 17. Palatine tooth, natural size. '1|, 5, 6 c a iLigu-aiJiiiiair u fffllir (Fittrttoriies. tU xxr. 1-2^ PLATE CARPUS CORYPHAEUS. 3-6. P TECTULUS, 7-13. P CURTIROSTRrS, 1^-17. CLIDASTES CINERIARUM. ' Sinclair iSon.litix.Plii'ia EXPLANATION OF PLATE XXII Clidaatea plani/rons, Cope, one-half natural size. Fig. 1. Superior view of parts of cranium preserved, including parts of the parietal (a), postfroutal (i), prefrontal (f/), and fronto-nasal (c) elements. 2. The same, seen from below. 3. Posterior part of k'ft mandibular ramus, without angle. 4. Median portion of rif;ht mandibular ramus, showing liingo. In both figures, a is the coronoid, h the surangular, c angular, d articular, and e splenial. 5. Portion of the right quadrate bone: 5, proximal part, inner view; 5 o, proximal view of tho same ; t) h, external view of the same. 6. Distal portion of left quadrate, external view ; 6 a, internal view ; G ft, posterior view. 7. Eight palatine bone, from below ; 7 a, right palatine bone, from outer side. M, $,>(SraLiitn:cal5.url:irp M'tlur Ctrr'Aiarirs. Mvitf xxn, ^^S^%. ^^.- CLIDASTES PLANIFRONS. EXPLANATION OF PLATE XXTIT. Figs. 1-14. CJidastcs plan'ifrnna, one-half n.itural size. Fig. 1. Eight iienr.ipophysis of the atlas. 2. Axis, with odontoiil bone, hypapoiibysis of latter wantins; 2 6, the same, inferior view. Figs. 3-6. Cervical vertebra; in order; a, free hypapophysie, proximal surface; 6, inferior, c, anterior, d, superior, and, e, posterior views of the same. Figs. 7-13. Some of the dorsal vertebra; in order; 7 6, the (?) first dorsal from below; e, from in front; and, r, from behind ; 13 h, a posterior dorsal from below; c, front; e, posterior extremity. Fig. 14. Basi-oceipital and part of sphenoid, from below. 15. Exoccipital, from above and behind. Figs. 16-18. Sironectes angidiferus, one-half natural size. Fig. 16. ? Third cervicil from above, exhibiting zygosphen. 17. Last cervical, displaying zygautrum; zygosiihenal articulation indistinct, through error of artist. 18. Terminal portion of the articular bone from the outside, showing the suture with the snr- angnlar. \%, S, 6caiLU]lral Sainiru rf iljc Ctrrjfejws 1-15.CLIDASTES PLANIFRONS. 16-18. SIRONECTES ANGULIFERUS. EXPLANATION OF PLATE XXIV. Figs. 1-14. Sironectcs aiigiiliferus, one-balf natural size. 1-2. Two consecutive cervical vertebroj, the Ubiril and fourth followed by an interval, from which one or two vertebras are missing; inferior view. 3-5. Five consecutive cervical and dorsal vertebra?, seen from below: 3, last cervieals; 4-5, ante- rior dorsals. Like 1 and 2, these have suffered somewhat from depression. Fig. G. a free cervical bypapophysis ; a, proximal view. Figs. 7-12. Vertebra", from the anterior portion of the caudal series which bear diapopbyses, commencing with the more anterior; 7 a, front; 7 b, posterior view of 7; 8 a, inferior view of number 8; 10 (I, inferior view of two caudals (fig. 10), with broken chevron-bone on the anterior; 12 a, anterior, and, b, posterior view of 12, a distal one of the series. 13-1.''. Ribs: 13-11, proximal, and, 1.5, median portions. EXPLANATION OF PLATE XXV. Vertebra? anil limb-boues, etc., oi riatecarpus iclericus, from Professor Mudge's collection, oue-ba'f natu- ral size. From figs. 1-25 belong to one individual, and figs. 26-27 to a second. Fig. 1. Scapula. 2. Fragment of coracoid. 3. Humerus : a, from outside ; I, from proximal ; c, from distal end. 4. Radius. 5. Carpal bone. FiG.s. 7-10. Supposed metacarpals, with (0 a and 7 a), their distal extremities. 11-20. Phalanges, with, a, their proximal, and, h, their distal extremities. Fig. 21. A cervical rib. 22. A dorsal vertebra, viewed from behind. 23. A dorsal vertebra : a, from the side ; 6, from below ; c, from (he front. 24. Tlie palatine bone, from below. 2.'>. Ulna of a second si>ccimen. 20. Metacarpal of the same. :H , § > 1C5.C0 tutgkjtl ^.iitflrcD flf IIk Cr r.rito ri r? , pJjvtcA-X' .-;"■ Sir.;:aiL'i: hfir. ;aai i PLATECARPUS ICTERICUS. EXPLANATION OF PLATE XXVI. Figures of vertebriB and limb-boues of rijthonomorplia, one-half natural size. Fig. 1. A scries of 23 caudal vertebriB of an undetermined species, taken from Butte Creeli bluffs ; tbe series is continuous except a definite interruption at the 15tli, and two or three possibly in front of it: a, posterior surface of 28th vertebra; 6, posterior surface of 24tU verteljra; c, posterior surface of the 21st vertebra ; cl, the same, from the front ; e, the 13th, from beliind ; /, the 13th, from the front. Many of the neural spines indicated by outliues are preserved on separate pieces of rock. 2. riatecarpits fjHMfZjei, specimen from Fox Canon : a, posterior part of mandibular ramus from within, one-half natural size ; b, posterior part of right dentary, natural size : c, posterior part of left dentary, natural size ; d, coronoid bone, one-half natural size, from the outside; e, corouoid bone, one-half natural size, from the inside. 3. I'latccarpus muilgci, from Professor Mndge's collection, original type : a, hypapopbysis of axis, from below ; b, hypapopbysis of axis, from behind ; c, centrum, or basal ])art, of atlas ; d, articular extremity of scapula. 4. Middle dorsal vertebra of rialccarpua crassariun, Cope, from Professor B. F. SIndge's collection, profile : a, from front. 5. Adjacent vertebra of same, profile : a, from front ; b, from behind ; c, from below. 6. Lumbar vertebra: «, from behind; b, from below. 7. Anterior caudal vertebra, from front. 8. Caudal with diapophysis : a, from behind ; b, from below. 9. Humerus of Platecarj)as craasartus : a, from within ; b, from without ; c, proximal end ; d, distal end. 10. Femur of same : a, from within ; b, from without ; c, proximal, and, d, distal exti'eraities. 11. Fibula of same : a, from side ; b, proximal ; and. c, distal extremities. 12. Phalange of same. 13. Cervical vertebra of I'lalecarpns . Hypapophysis of axis: a, from above; h, from below; somewhat distorted by pressure. 7. Hypapophysis of a median cervical vertebra. 8. Preniaxillary and part of maxillary bone of Liodon proriger, iu profile. 9. Premaxillary bone of Liodon proriger, from below. tl . f . (Sf okgksdSjffti-fii sfllrc f m-JJjirirs >ltt XXVJil. 7 LIODON DYSPi^L^^- ^'S-LIODON pRuRiGER. EXPLANATION OF PLATE XXLX. Vertebra; of Zio(fo« (f.i/.s/K^or, from Butto Creek, ODC-balf natural size. They are selected from various points in the cohimn, the best-preserved being preferred ; most of tbe dorsal and caudal vertebraj are omitted. Fig. 1. Atlas and axis from tbe side : a, ceutrnm of atlas ; h, nenrapojibysis ; c, bypapopbysis ; d, centrum of axis, free bypapopbysis omitted {sec Plate xxviii, fig. 0). 2. Last cervical. 3. A posterior dorsal. 4. A lurabo-sacral, witb its posterior face npward, witb i:pural areb on rigbt, and diapopbysis on left side. Figs. 5 to 6. Caudal vertebriB. 11, S". 6f iiUigkal^wnifu ifrtl)! plaic \-xix tiuivlur i. if>r. iiUt I itilo . LIODON DYSPELOR COPE, EXPLANATION OF PLATE XXX. VertebriB o{ Liodon dyspeJor, from Butte Creek, and L. prorigcr, t.vpe-speciiueii, oue-balf uatiiial size. Fig. 1. Third cervical vertebra of i. (lyspelor, from below. 2. Fifth cervical vertebra, from behiud ; slis^htly distorted by iiressure. ;!. Middle cervical, from behind. 4. Last cervical : a, from behind ; h, from below. 5. Anterior dorsal vertebr.a: a, from front; h, from rear, fi. Middle dor.sal, centrum from behind. 7. Posterior dorsal, centrum from behind. 8. Posterior dorsal or anterior lumbar : a, from behind ; 6, from below. 9. Three consecutive lumbar vertebras, from below. 10. Cervical vertebra of Liodon pro>ig(n; from the front; belonging with the remaining tigiues to fig. 14, inclusive, to the type-specimen in the Museum of Comparative Zoology, Cambridge. 11. Anterior caudal vertebra of the same individual, from behind. 1'3. Median caudal : a, from front; i, from the side. 13. Posterior caudal vertebra : a, from front ; h, from side. 14. Four distal caudals, profile. ll.f .6cokJii«alSAmi,cv) of-U)iL- ^ctritori Pbx\t XXK. * SOI, iim PJllU „., T^r^cPELOR 10-I4-, LIODON PRORIGER. 1-9. LIODOM DY&PEL ^^^j^^,^^^^^^^^^ EXPLANATION OF PLATE XXXL Figs. 1-3. Vertebra: of the LioHon di/upclor from Butte Creek, one-lialf uatural size. ri(i. 1. Atlas and axis from the front, the odontoid bono wanting: a, axis; b, neurapojihysis of atlas ; c, basal element of atlas ; tl, hypapopliysis of the odontoid. 2. Axis, posterior view. 3. Third cervical vertebra, from boliind. 4. Six caudal vertebrai of Ziodon dijajnlor, consecutive, except an interval between the third and fourth ; one-third natural size. Of the anterior three, the diapophyses of the left side aro broken off, and the neural spines, being turned to that sideHjy jiressnre, arc displayed. From the specimen figured in Plates xxvii-xxx. T). Centrum of a lumbar vertebra of Liotlon dijupdor, from behind. From the type-specimen in tho Muaeum of the Smithsonian Institution, from Fort Mi-Rae, New Mexico. -It, !^. [''-iraliuiKul :?unici' i-i-rUn- Clf ttitorii ffe'crXXXT. LIODON DY3PEL0R. EXPLANATION OF PLATE XXXIL Shoulder-girdle and anterior limb of Liodon dyspelor, from preceding sijecimen, one-half natural size. Fig. 1. Scapula; a, articular extremity. 2. Coracoid. 3. Humerus: a, from inside ; J, fron; outside ; c, proximal; ra No. 33, posterior view. 10. Cauda! vertebra No. 42, anterior; a, posterior views. Figs. 11-14. Liodon jic/itFo/iexs, Cope, one-half natural size. Fig. 11. Quadrate boue from outside ; «, from inside ; h, proxinially ; i rt j o f t^ fi 1 — 1 B O m a K o^ J?" O 5 > CO > O 00 EXPLANATION OF PLATE XXXVL Palatine boues of Pyllionomorpha, onu-half uatunil size : a, from tbo outsiUe ; h, from tbe inucr side ; and, c, from below. , Fig. 1. Liodon clyapelor. 2. Liodon proriger. 3. CUdastes tortor. 4. CUdastes stenops. 5. Flaiecarpus curtirostris. 6. Flatecarpua cort/phcctis. 7. PJalecarpua ictcricua. EXPLANATION OF PLATE XXXVIL Quadrate bones of seventeen species of Pi/thonomorjjha. From fi^s. 1 to 11, one-hiilf natural size ; figs. 12 to 17, one-third natural size. In all, fig. a represents tbe external side ; fig. h, tbepostero-internal, or internal view ; fig. c, the proximal ; and, fig. d, tbe distal articular faces. In figs. 5, 10, and K!, the angles and ridges are indicated as follows : a is the " knob," or the ridge homologous with it ; ji, median posterior ridge ; y, the distal internal longitudinal ; (5, the internal longitudinal, or simply the internal ridge; e, the proximal internal angle ; C, the alar process. Tig. 1. CUdastes in-opython. 2. CUdasles tortor. 3. CUdastes stenops. 4. Liodon ralidus. In fig. c, tbe internal angle of the prosiuial articular face is turned to the left It should be turned to the right, in order to correspond with figs, a and fc, and those of tHe. other species. Moreover, the posterior book and alar process are broken away. 5. Liodon di/spelor. G. Liodon prmiger, flattened by pressure. 1 .' Platecarpus mudgci. 8. Platecarpus ictericus. 9. Plalecarpua comjpJiceua, 10. Platecarpus curlirostria. 11. Platecarpus tympanUicus. \'l. Mosasaiirus dcpreasus. K^. Mosasaurus fuJciatus. 14. Mosasaurus gigantcua. Ui. Mosasaurus maximus. IG. Mosasaurus dcJcayi. 17. Mosasaurus oarihrut. MJ .iSwkigicalf itrticu of-tlic fttritorits pak Kxxm. QUADRATE BONL'S. OF pYTHONOMOHPHA. T^CLiDASTES. ^.-o. LIODON. 7-U. PLATECARPU^ ^•SAURUS. EXPLANATION OF PLATE XXXVIII. Restorations of crania of three species of Pi/lhonomorjilui, viewed from above, oue-tbinl nalural size: rmj-., premaxillary bone; i/x., maxillary; Prf., prefrontal; Fi:, frontal; Pof., postfrontal; Fa., parietal; Pro., prootio ; £xo., exoccipital ; Opo., opisthotic; iSg., squauiosal. FiO. 1. Platecarpus curtirostris. '2. Clidastes tortor. 3. Clidmtts sienoj)), parietal region inferential. M.S.63:0l08kai:f Affirru rfiJfs.- aftrjtorifs. IrVlcX'ca'm. Th'^ amclair k Son "lith, Pliila ._ 1. PLATE CARPUS CURTIROSTRIS. 2. CLIDASTES TORTOR. 3, CLIDASTES STENOPS. EXPLANATION OF PLATE XXXIX. Cranium of Porlheus moJossus, Cope, type-specimen, natural size ; the maxillary and mandibular arches separated from their normal iJositious, so as to display the teeth and articulations. •11, S. 6rDl).i0ital ^HWf 1) rf-Uif g-ttt'ftorifs .ritJl08iiC5Ji S-Uftifis rfitljc Jif ti-feris'Si. L»-tcxi.n!. v^**^-^^^: PORTHEUS THAUM^vS. '.'x' Sinclsir k Sor. litii. I'r EXPLANATION OF PLATE XLIV. Figs. 1-4. Portheus ihaumns type, natural size. Fig. 1. Part of vertebral col umu. 2. Terminal vertebra^ with hasnial and neural spines supporting caudal fin ; a, first fan-shaped ha?uial spine. • 3. First fan-shaped h;tmal spine, viewed from above ; 3 a, the same, proximal articular face. 4. llargiual rays of caudal fin. 5. Fragmeutarypectoral spiue of the type-specimen of Fcu'theua molossiis, Cope. Figs. 6-9. Ventral spines of a Saiiroclont, found together, species nukuown : C, the first; 7, the second; 8, third; a, oiiposite side of same; 9, basis of one more distal. 10-11. Scapula of Fortheus moJossus, type-specimen ; inverted. Fig. 12. Pectoral spine of Fekcoptenis gladius ; a, from anterior edge. 13. Pectoral spine of Fch-copteriis 2)eriiiciosus ; a, from posterior edge. 14. Part of vertebral column of type of IchlhyocUctes anaidcs, Cope, found iu position, natural size. 15. Vertebra} of the same siiecimen. \l, f . fifiilugkalSiinirv rf-Uic Ccrrtorifs |Jl'aic xu\. 4'. PORTHE'US THAUMAS, 5,10-il P MOLOSSUS6-9PORTHE ^^ INDRT 14-15. ICHTHYODECTESANAIDES. EXPLANATION OF PLATE XLV. Figs. 1-8. Icldhyodectes anaidcs, Cope : flgs. 1-4 and G, one-half natural size ; figs. 5, 7, and 8, natural size; from one, tbe type-specimen (see Plate XLIV, fig. 14). Fig. 1. Mandibular rami, lying on a block of yellow cbalk. 2. Preniaxillary bone, outer side. 3. Preniaxillary bone, inner aide. 4. Right maxillary, outer side, f). Sclerotic bones of the same. C. Hyomandibular, 8yuii)lectic, and quadrate bones. 7. Femoral boues, from below; 7 a, from behind. 8. Pectoral spine. Figs. 9-11. Terminal caudal vertebras of Porlhcus molossKS, from above; a, from front; h, from side. 12. Jaw of Bryactinus amorphus, Cope (p. 282), natural size : a, profile ; 6, masticating face ; c, oppo- site border. From the greeiisaud of New Jersey. -Ill, f,l$iM}lcri|knl^WPrD jrfiljc Inrittirws. Ibds XI,T, ICHTKYODECTES ANAIDES. 9-12. PORTHEUS MOLOSSUS. 13, BRYACTINUS AMORPHUS. ' Sinclair &. Son luh .PKila . EXPLANATION OF PLATE XLVL Figs. 1-4. Ichfhyodectes ctenodon, Copo, natural size. Fig. 1. Maxillary boue, from tbo outside. 2. Dentary bone, from tbo inside. 3. Hyomandibular boue. 4. Cervical vertebra. 5. Ichthjodcctes hamaliis, Cope, natural size : B, premasiUary and maxiUary bones, from tbo outer side ; 5 a, mandibular ramus, from tbe outer side. Figs. 6-10. Icldhtjodecics prognathus, Cope : 6, tbe premaxillary, with anterior extremity of maxiUary, from tbe inner side ; G a, same, from tbe outer side ; natural size. 7. Ventral spine accompanying the same, natural size. 8. Cervical vertebrse, one-balf natural size. 9. Dorsal vertebrje, one-balf natural size. 10. Terminal caudal vertebno, with articulating spines ; one-half natural size. 11. Maxillary bone o{ Pachjrhhodus kiiigii, from tbe inner side, natural size. 12. Three vertebrai of Anogviiiis, largest species, accompanying remains of JcMhjodictea ctenodon, one-balf natural size. 13. Cervical vertebraj of a ? Portlieus, one-half natural size. ll^S.lScaliigifalSxnniru rf-tljjr (IrtritorifS.. Mixit XLVi . .jinciair AL ior, .iti". 1-4. ICHTHYODECTES CTENODON. 5. I.HAMATUS. 6-10. 1 PROGNATHUS. 11. PACHYRHIZODUS KINGII. 12. ANOGMIUS. EXPLANATION OF PLATE XLVII. Muzzles and crania o{ Saurodontida;, natural size. Fig. 1. Inferior view of vomer and ethmoid bones of Portheus Icstrio, Cope, obliquely depressed, display- ing cotyli for the maxillary and premasillary condyles. 2. Inferior view of vomer and ethmoid of an unknown species, not distorted. 3. The same view of Duptinun x^hlcholomus. 4. Superior view of the same specimen. ."J. Profile of an unknown Saurodont. 6. .Suijerior view of ethmoid of Duptiii us phhhotomm, Cope. 7. Inferior view of cranium of Portheus larcuatus. 8. Superior view of the same cranium. 9. Palatine bone, with malleolar body, of Portheus arcuatus, from the outer side. -Vl , $ , .(S f inLegkai SAtfti f ^ M'ilrc l^ic«jital bone. 3. Element of uncertain position. 4. Supposed hyomandibular ; ou the same block as the next — fig. 5. Supposed interoperculum. (i. Uncertain piece, perhaps symplectic. 7. Lateral view of a vertebra accompanying the same. 8. Pachyrhizodus leptopsis, Cope, mandil>ular ramus, natural size: o, distal half of dentary bone, from within ; fc, proximal part of the same bone ; c, vie w ( f distal or s^ mphyseal end of the Bame. M , S. dnnb^aicM ^mvcu rflJ?c .CtrrJlUirirs, JV- 4 i^ m\t M. t_Sl^,AX^ y fl^, :*^ ll" auidairJcSonlithPHla. 1-7 PACHYRHIZODUS LATIMENTUM. 8. P. LEPTOPSIS. EXPLANATI(3N OF PLATE LII. Fig. 1. Empo nepwolka, Cope, bead and anterior part of the body, on a block of tbe cbalk of the Niobrara beds, from Professor Merrill's collection: a, ft, right preniaxillary and dentary bones; c, d, left premaxillary and deutary bones ; e, frontal bones ; /, ectopterygoid ; g, quadrate; h, denual scuta; i, pectoral fin ; one-half natural size. 2. Pelecopterus pernicioms, Cope, spine of pectoral fin, one-half natural hize. 3. Pectoral spine of Pelecopterus gladius, Cope, oue-hnlf natural ."ize ; from Professor Mudfje's col- lection. 4. Beryx insciilptiis, Cope, from Dr. Lockwood's collection, one-half natural size; a, scales, natural Bize. .f.6wloa«'''i^«*fi! ''™"' ^"■f''^"'^'"s , y7y;^Z^r^jm'M^<:'. ' ':?/9J%^ |fla-tc in. EMPO NEPAEOLICA 2, IGHTHYODECTES PERNISIOSUs. s.pqrtheuS GLADIUS 4.BERYX INSCULPTUS, II" SxnclAirJbSan'liiK.PiiiU. EXPLANATION OF PLATE LIII. Fig. 1. Vertebral column, with pectoral fin, and impression of operciila of Empo sfmiaiiceps, Cope, one- half natural size ; an interruption between the dorsal and caudal series is not filled by the specimens : 1 a, obverse of the piece containing last dorsals, showing dermal bones. 2. Opercular, hyoraandibular, quadrate, and angular bones of another specimen o{ Enipo scviianctps one-half natural size. Figs. 3-.5. Parts of a single specimen oi Empo nrpwolica. Fig. 3. Tho mandiliular ramus, natural size, from the inner side ; 3 a, the same, from the outer side ; 3 b, the angle and cotj'Ius, iiom behiud. 4. Premaxillo-niaxillary bone of the same, natural size, viewed from below. 5. Cervical vertebrai and basioccipital bone of the same, from below, one-half natural size. Figs. 6-9. Portions of a skeleton of Empo scmianceps, natural size. Fig. 0. Dentary bone, from the outside. 7. ? Pharyngeal bone, with dental alveoli. 9. Dermal scuta. Figs. 10-13. Empo merriUii, Cope, natural size. 11-12. Premaxillary bone, from below. Fig. 12. Proximal end. 13. Pharyngeal bone, with alveoli. Figs. 14-17. Empo conlrucla, Cope, natural size. Fig. 14. Pharyngeal bone, with alveoli. 15. Premaxillary and maxillary bones, from below. 16. Proximal side of premaxillary, from the side. 17. Dentary bone, from outer side. pale JM. 1-2. EMPO SEMIANCEPS. 3-5, EMPO NEPaeqlica. 6-9.EMP0 SEMIANCEPS. 10-13. EMPO MERRILL" H-iy. EMPO CONTFiACTA. EXPLANATION OF PLATE LIV. Figures natural size, except (ig. 0, wliicU is tliree-fourtbs nature. Fig. 1. Preniaxillary and part of maxillary bones of TellKodim prpki-edo, Cope, natural .size, from the outor Bide ; a, same, from inner side; 6, same, from lower side. 2. Distal end of left dentary bone of the same, outer side, in natural relation with fig. 1. 3. Distal eud of right dentary, from outer side; a, from above. 4. Left premaxillary and part of maxillary bone of Enchodus pctromigj Cope, from the inner side; a, same, from outer side. 5. Distal end of left dentary, from inner side, iu relation with tig. 4 ; o, the same, from above. 6. Base of posterior partf of crauium of the same: a, basiiiccipital ; h, exoccipital; c, opisthotic; d, pterotic. 7. Premaxillary and part of maxillary bone of Enclwdua duVuhiis, Cope, from outer side; a, same, from below. 8. Scapula of Pelecopteriis chirurgus, exhibiting the facets for articulation of the two large and six slender basilar bones. it, ^ , 6 wkifltcai $.mif I) ffOMs: actrifetiifs. Iibtif i;iy. eclair & Sor. litK Pi\ils. 1-3.TETHE0DUS PEPHREDO. 4-6.ENCH0DUS PETROSUS. 7-8.ENCH0DUSD0LICHUS. ':). PELEGOPTERUS CHIRUROUS EXPLANATION OF PLATE LV. Restoratious. 1. PorlhcKS, one-finirtcpiitb natural size. 2. Cliclastes, one-twentieth Datnral size. 3. Platecarpua coryphcrus, outline of the imperfect cranium of the type-spccimon. M, §. (Sffliiigiral^w^'™ i)f tiif f .cgltorifa. 'R«J. 6i"obulc;al^i!viU'u irrfhc (Lciti-hu-i ts. PlcVlc TO. i h '% -.4 ^ % *w-5:: --^1^ g«M:r ^AmT ■ f 'V 2a HAPLuSCOPHA GRANDIS, EXPLANATION OF PLATE LVIL Saploscapha eccenii ica, Conrad, oue-third natural size ; the extremity of the hinge-bonier broken off. Fig. 1. Internal view. tJ. Outer side of the same shell, covered with Ostrca contjesta.