. . LIBRARY . . Connecticut Agricultural College. VOL... J)....b.4..1 _..... CLASS NO ■rf....-A...>f. COST . ^....9^....-^:.: DATE ._*.. A „19.:... Digitized by the Internet Archive in 2009 with funding from Boston Library Consortium IVIember Libraries http://www.archive.org/details/pseudoceratitesoOOhyat DEPARTMENT OF THE INTERIOR MONOGRAPHS OF THE United States Geologtcal Survey VOLUME XLIV WASHINGTON GOVERXMENT PRINTING OFFICE 1903 UNITED STATES GEOLOGICAL SURVEY CHARLES I). WALCOTT, DIRECTOR PSEUDOCERATITES OF THE CRETACEOUS BY ^^Ll^ECETJS HY^TT Edited by T. W. STANTON WASHINGTON GOVERNMENT PRINTING OFFICE 1903 ^i.il CONTENTS Page. Editor's preface ^'■ Cla,ssified list of families, genera, and species 15 Table of horizons ^^ General remarks 1" Systematic descriptions -'^ Mammitida ■ -'^ Mojsisovicsiidfe '"'^ Buohiceratid:e -*> Pseudotissotiida' •^'^ Tissotiidfe "^1 Sphenodiscida? ■^** Eulophoceratidw 83 Coilopoceratidfe ^^ Cosmoceratida I'^l Mantelliceratida ^'^^ Mantelliceratidfe 105 Metoicoceratid?e 115 Heinziidfe 1^8 Palchelliid:e l'^6 Kuemiceratidse 1" Engonoceratidfe 153 Placenticeratidie 1^8 Bibliography -"'" Plates 251 Index ■^■^7 5 ILLUSTRATIONS Plate 1. Figs. 1-3. 4-9. 10-14. 15. II. Figs. 1-3. 4-6. 7-11. III. Figs. 1-6. 7-15. IV. Figs. 1, 2. V. Figs. 1-3. 4. XI. Figs. 1, 2. 3,4. 5. 6. VII. Figs. 1,2. VIII. Figs. 1, 2. 3-7. IX. Figs. 1-6. 7-9. 10. 11-13. X. Figs. 1-4. 5-21. XI. Figs. 1. 2-6a. 7-24. XII. Figs. 1-3. 4-6. 7. 8. XIII. Figs. 1, 2. 3-5. Page. 254 Mojsisovicsia durfeldi Steinmann Buchicera.s bilobatum Hyatt Roemeroceras syriaciforme Hyatt Roemeroeeras attenuatum (Hyatt) Roemeroceras gabbi Hyatt 1 Roemeroceras subplanum Hyatt [ 256 Paratissotia serrata (Hyatt) J Paratissotia regularis Hyatt i Sphenodiscus pleurisepta (Conrad) / Sphenodiscus pleurisepta (Conrad) Sphenodiscus pleurisepta (Conrad)i Sphenodiscus stantoni Hyatt J Sphenodiscus lobatus (Tuomey) Sphenodiscus beecheri Hyatt Sphenodiscus stantoni Hyatt Sphenodiscus pleurisepta (Conrad) Sphenodiscus lobatus (Tuomey) 266 Sphenodiscus lenticularis (Owen) i Sphenodiscus lenticularis var. splendens Hyatt ' Sphenodiscus lenticularis (Owen) Sphenodiscus lenticularis var. mississippiensis Hyatt Sphenodiscus beecheri Hyatt Sphenodiscus lobatus (Tuomey) Coilopoceras noviniexicanum Hyatti 258 260 262 264 268 270 Coilopoceras colleti Hyatt Coilopoceras colleti Hyatt Eulophoceras natalense H>att Metoicoceras svvallovi (Shumard Coilopoceras springeri Hyatt Aconeceras nisum (d'OrVjigny) Coilopoceras grossouvrei Hyatt Sphenodiscus konincki Hyatt Metoicoceras swallovi (Shumard )i Metoicoceras whitei Hyatt r- /■ 274 276 278 8 ILLUSTRATIONS. Page. L.rrE XIV. Figs. 1-10. 11-14. 15. 16. XV. Figs. 1-4. 5-8. 9-11. 12-18. 19-20. XVI. Figs. 1-3. 4-8. 9,10. 11-14. 15-18. 19. XVII. Figs. 1-5. G-S. 9-12. 13-15. 16-20. XVIII. Figs. 1-3. 4,5. 6-9. XIX. Figs. 1-6. 7-14. 1.5-17. XX. Figs. 1-5. 6-13. XXI. Figs. 1. 2-6. XXII. Figs. 1-5. 6-10. XXIII. Figs. 1-6. 7-9. XXIV. Figs. 1-5. 6-8. XXV. Figs. 1-4. .5-9. XXVI. Figs. 1-4. 5-7. 8. XXVII. Figs. 1,2. .3-14. 15-17. XXVIII. Figs. 1-6. 280 282 284 86 Metoicoceras whitei Hyatt Metoicoceras acceleratum Hyatt Metoicoceras whitei Hyatt Vascoceras hartti Hyatt Metoicoceras swallovi (Shumard Metoicoceras gibbosum Hyatt Metoicoceras kanabense Hyatt Heinzia matura Hyatt Heinzia provincialis (d'Orbigny) Heinzia provineialis (d'Orbigny) Knemiceras syriacum (von Buch) Knemiceras compreasum Hyatt Knemiceras compressum var. subcompressuiii Knemiceras compressum Hyatt Knemiceras compressum var. suVx-omiiressum Sabpulchellia castellanensis Hyatt Nicklesia dumagiana Hyatt Pulchellia compressissima (d'Orbigny) Knemiceras attenuatum (Hyatt) Protengonoceras gabbi (Bohm) Knemiceras gabbi Hyatt "l Engonoceras belviderense (Cragin) > 288 Protengonoceras planum Hyatt J Engonoceras uddeni (Cragin) 1 Engonoceras serpentinum (Cragin) \ 290 Engonoceras retardum Hyatt J Engonoceras serpentinum (Cragin) -i Engonoceras pierdenale (von Buch) I Engonoceras pierdenale var. commune Hyatf Engonoceras subjectum Hyatt Engonoceras subjectum Hyatt i Engonoceras gibbosum Hyatt / Engonoceras gibbosum Hyatti Engonoceras stolleyi Bohm ' Engonoceras stolleyi Bohm i Engonoceras complicatum Hyatti Neolobite.s choffati Hyatt \ Metengonoceras inscriptum Hyatti Metengonoceras inscriptum Hyatfl Metengonoceras ambiguum Hyatt > Metengonoceras acutum Hyatt J Metengonoceras acutum Hyatt 1 Metengonoceras dumbli (Cragin) \ Placenticeras syrtale (Morton) J Placenticeras syrtale ( Morton) 292 294 296 298 300 302 304 306 W8 ILLUSTRATIONS. 9 Page. Plate XXIX. Figs. 1-4. Plaeenticeras? guadaluiue ( Roeuier) .310 XXX. Figs. 1-3. Placenticeras t-ancarlosense Hyatt 312 XXXI. Figs. 1,2. Placenticeras sancarlosense Hvatti 3-5. Placenticeras newberryi Hyatt I XXXII. Placenticera.s sancarlosen.se var. pseudosyrtale Hyatt 316 XXXIII. Figs. 1. Placenticeras sancarlosense var. nseuilosvrtale H\attL ' 31S 2-4. Placenticeras planum Hyatt ' XXXn'. Figs. 1-3. Placenticeras planum Hyatt 320 XXXV. Figs. 1, 2. Placenticeras intercalare Meek 322 XXXVI. Figs. 1-5. Placenticeras intercalare Meek 324 XXXVII. Figs. 1-4. Placenticeras intercalare Meek 326 XXXVIII. FiiTs. 1. Placenticeras intercalare Meek i [ 308 2. Placenticeras intercalare var. costatuni HyattI XXXIX. Figs. 1,2. Placenticeras intercalare var. costatuni Hvatti /■ 3*^0 3-6. Placenticeras placenta (DeKay ) I ^ XL. Figs. 1,2. Placenticeras placenta (DeKav) 1 33*^ 3-7. Placenticeras stantoni var. belli Hyatt ' " XLI. Figs. 1-7. Placenticeras stantoni var. belli Hyatt 334 XLII. Figs. 1, 2. Placenticeras stantoni var. bolli Hyatt 330 XLIII. Figs. 1, 2. Placenticeras stantoni var. bolli Hvatt-i "1 ' J " s .3-1 1 . Placenticeras pseudoplacenta Hyatt ' XLI V. Figs. 1-3. Placenticeras pseudoplacenta Hyatt 340 XLV. Figs. 1, 2. Placenticeras pseudoplacenta var. occidentale Hyatti .3-16. Placenticeras whittieldi Hyatt / XLVI. Figs. 1, 2. Placenticeras whitfieldi Hyatt .344 XLVII. Figs. 1—1. Placenticeras whitfieldi Hyatt I 5. Placenticeras whitfieldi var. tuberculatum Hyatt j- 346 6-8. Placenticeras spillmani Hyatt EDITOR'S PREFACE. Soon after Professor Hyatt's lamented death, January 15, 1902, it was the writei''s sad duty, as a representative of the United States Geo- ological Survey, to examine all the paleontological collections and manu- scripts in Professor Hyatt's house in Cambridg-e, in order to take possession of those belonging to the Survey. The manuscript of the present volume was on his desk and contains the results of his last work, in which he was actively engaged on the day of his death. Fortunately it was almost readv for the printer, and although the careful reading of the manuscript to determine the author's exact meaning and intentions has consumed con- siderable time, the changes, either in arrangement or in wording, and the additions that have been found necessary are very few indeed. These changes are all indicated in their proper places by footnotes or bracketed statements signed b}' the editor's initials, except the unimportant verbal change of "Cretacic" to "Cretaceous," made for the sake of conformity with Geological Survey usage. In his recent writings Professor Hyatt consistently followed the International Geological Congress rule of ending names of all periods and systems with "ic." The preparation of this work occupied a large part of Professor Hyatt's time for several j'ears. As early as 1897 a manuscript with the same title was submitted to the Director of the United States Geological Survey for publication, and soon afterwards the preparation of the illustra- tions was begun. A copy of this original manuscript now in my hands shows many important differences in aiTangement, classification, and nomenclature from the later manuscript, indicating that it had been thoroughly i-evised and recast in connection with a restudy of the fossils. Although there are some minor inconsistencies, and there would doubt- 11 12 EDITOR'S PREFACE. less have been some other (-hanges and additions if the author liad lived to see the work through tlie press, it is believed that as now published it fairly presents his latest views. The illustrations were all made under Pro- fessor Hyatt's supervision, except a few, which were definitely selected and indicated by him, and most of which are copies of published figures. He had also mounted the figures on the first twenty plates and had written the descriptions oi nineteen of the plates. The other figures were nearly all labeled with specific names. The manuscript was in two packages, one of which began with the "General remarks," followed by Pulchelliidse, Knemi- ceratidfe, Engonoceratida;, and Placenticeratidfe, which is nearly the arrangement of the original manuscript of 1897, while the second package began with Mojsisovicsiida> and ended with Coilopoceratida'. The plates arranged by the author contain all the illustrations except the Placenticer- atidaj and a part of the Engonoceratidas. By transferring the introductory "General remarks" from one package to the other and then uniting the two packages the descriptions fell into practically the same arrangement that was adopted for the figures, and which evidently represented the author's latest views as to their relationships. The assignment of the fami- lies to higher groups was not fully carried out by Professor Hyatt, and it is thought best not to attempt to complete it, in view of the fact that his opinions as to the definition and limits of the diff"erent superfamilies evi- dently were much modified, though never formulated, after the publication of his chapter on Cephalopoda in Zittel's Text-l)ook of Paleontology. In that work he divides the Aramonoidea into several suborders, and between these and the families there is another unnamed categor}- of groups, which may be called supei-families, such as Mammitida, Cosmoceratida, etc. Part of the Pseudoceratite families are there referred to Mammitida, part to Placenticeratida, the Pulchelliidse were accidentally omitted, and f«ther families were not there described. In the present paper a list of the fami- lies belonging to the Mammitida is given, but beyond that group the clas- sification is doubtful. In connection with the description of Vascoceras, Cosmoceratida is mentioned in such a Avay that the reference of the genus to that group may be inferred, and later in the manuscript the heading :\Iautelliceratida is inserted, but there is nothing to wan-ant the assumption EDITOR'S PREFACE. 13 that the latter term was mtended to include HeinziidiT?, PulcheUiida?, Kneini- ceratidse, Eugonoceratidse, and Placenticeratidji?. In the jiuliHshed work above referred to, the two families last named are united whh Spheno- discida? to form the Placenticeratida, but with the removal of Sphenodis- cidffi to Mammitida it seems probable that the superfamily Placenticeratida was abandoned. The multiplication of families, g-enera, and species will be understood by all who are acquainted with Professor Hyatt's habit of attempting to express in the terminology every important fact observed in the course of his investigations. In characteristic fashion the author plunges into the midst of his subject, beginning his introduction with a discussion of the sutural details of Jui-assic ammonites, not tan-ying even to define the title of the paper or to make a formal statement of the problems involved. In a footnote on page 546 of Zittel's Text-book, where he first used the term Pseudocer- atites, he states that it "is a descriptive expression for the Placenticeratida and Tissotidfe of the Cretaceous, which are morphic equivalents of some Triassic genera of the Discocampyli as regards both suture and shell form. Their origin is traceable, however, to diff'erent groups of the Pachycampyli, a suborder which appears to have been initiated in the Jura along with the Leptocampyli. It is, therefore, improbable that the Pseudoceratites were directly connected with the Triassic Discocampyli." In a letter written December 26, 1901, in response to an inquiry from the Geological Survey oflice, he gives the following somewhat more definite statement of the scope and purpose of the present work: "I am at work finishing a 'Monograph of the Pseudoceratites of the Cretacic' This is an artificial group, includ- ing, for convenience of treatment, all the retrogressive genera of the Cre- tacic that have sutures with simple outlines resembling those of Triassic cephalopods, formerly included under the name Ceratites. The known genera described and figured ai-e Buchiceras, Tissotia and its allies, Sphe- nodiscus, Knemiceras, Engonoceras, Placenticeras. The aim of this publi- cation is to give as full treatment as possible of the structure and relations of these genera, in order to determine as far as practicable to what groups among the normal progressive forms they are most nearly related." 14 EDITOR'S PREFACE. It was Professor Hyatt's custom, in citing the autliority for a species, to give the name of the author who first referred the species to the genus in which it is now retained, instead of citing the one who first proposed the specific name. Thus he wrote Placenticeras placenta Meek, ahhough the form was described as Ammonites 2)lacenta by DeKay. This is not in accordance with the rule usually followed by zoologists, and the citations have been changed so that each specific name is followed by the name of the original describer of the species, with the author's name in parentheses if the generic reference has been changed. When the figured specimens were at the Geological Survey in the hands of the artists, Professor Hyatt requested the writer to examine them carefully and give him notes and comments as to the localities and horizons of the specimens from his own collection and from other museums. The quoted statements concerning various species that appear in the manuscript were extracted from the notes the writer then forwarded to him. The appended tabular statement is intended to show the relative positions of the various marine Cretaceous horizons and formations men- tioned in the text. It does not imply accurate correlation of American and European horizons, the line between Lower and Upper Cretaceous being probably somewhat higher in America than in Europe. The figured specimens that are mentioned in this paper as belonging to Professor Hyatt's private collection have now become the property of the Museum of Comparative Zoology in Cambridge. The writer has supplied the table of contents, tlie formal bibliographic list, and the descriptions of the plates after PI. XIX. T. W. Stanton. CLASSIFIED LIST OF FAMILIES. GENERA, AND SPECIES. In the following list all the groujis that are described an. defforgesi. reigi. haugi. Lopholiolite.s Hyatt. eotteaui. Knemiceratid^. Knemiceras Bohni. syriacum. coinpressuin. var. subcompressum. attenuatum. gabbi. uhligi. ENGONOCERATID.aE. Protengonoceras Hyatt, gabbi. planum. eniarginatmn. Engonoeera.s Neuuiayr. belviderense. uddeni. serpentinum. pierdenale. var. commune. subjeetum. gibbosum. stolleyi'. complicatuni. emarginatum. roemeri. Neolobites Fischer. vibrayeanus. choffati. ptToni. Metengonoceras Hyatt. inscriptum. ambiguum. acutum. dumbli. MON XLIV — 03 2 18 PSEUDOCEKATITES OF THE CRETACEOUS. Placenticeratid^. Placenticeras Aleek. guadalupa". sancarlosense. var. pseudosyrtale. planum, newberryi. syrtale. var. halei. intercalare. placenta, stantoni. var. boUi. pseudoplacenta. var. occidentale. whitfieldi. var. tuberculatum, spillmani. telifer. ? fallax. ebravi. Placenticeras warthi. nieinoria-schloenbachi. (lepressum. grossouvrei. incisum. niilleri. scliliiteri. orbignyanum. polyopsis. erassatum. taniulicuni. pseudcirbignyanum. subtili^Jtriatunl. Diplacmoceras Hyatt. Ijidorsatum. canaliculatum. Incert.*; sedis. Styracoceras Hyatt, balduri. Tahle of horizons mentioned in this work. Upper Missouri. Texas. Gulf border. New Jersey. Europe. Fox Hills. Navarro, Eagle Pass. Ripley. Manasquan Danian. MontHiia (Upper marl). Fort Pierre. Taylor, San Carlos. Selma( Rot- Rancocas i ten lime- (Middle stone) . marl). rCampanian. 3 Monmouth SenoniamSantonian. (Lower Iconiacian. u a; P. ft Niobrara. Austin. Eiitaw. marl) . M a t a w a n Colorado Fort Ben- l ton. Eagle Ford. (Claymarl). Turonian. Dakota. Woodbine. Cenomanian. Buda. Grayson. Main street. Albian. Gault llellisoii Paw Paw. X Washita Marietta. § _a3 Denton. 1 0) o g Fort Worth. IDuck Creek. Preston . . . [Kiamitia. Aptian. 1 a (Edwards. 3 6 Frederick.«burg|ciimanehe Peak. [Walnut. jPaluxy. Trinity joienrose. [Travis Peak. Barremian. Hauterivian. Neoeomian ,. , V rtlangian. Berriassian. PSEUDOCERATITES OF THE CRETACEOUS. By Alpheus Hyatt. GENERAL REMARKS. So far as I have, been able to see, either in figm-es or in specimens, the Amnionitinje of the Jura have only one large tirst lateral lobe, even in highly involute forms, as demonstrated by the admirable researches of Buckman" upon HyperUoceras discoidum, suhdiscoidum, etc., and the same has been shown by Oppel's figures* of Neumayria discus, hochstetteri, and aspidoides, and Quenstedt mAmm. trueUi,'and the similar hollow-keeled forms alsoiniVeif- mayria serrodens (pis. 24, 69), Polyplectus diseoides, and capeUinus (pi. 53), which have a very deeply divided and double first lateral, and in Neumayria discus (pi. 57) in which there are apparently two or three principal laterals, but in the neanic stage only one bifid first lateral The Arietidse seem to have two principal saddles owing to the great development of first auxiliary, but this occurs only in the ephebic stage. Aspidoceras and some forms of other genera often have two well-divided principal lateral saddles, but this again occurs through the late division of the primitive lateral. In fact, it may be confidently stated that in the Jura all of the Ammo- nitinse have but one principal lateral saddle throughout the neanic stage, and when, as very rarely occurs, two or three principal laterals are either apparently or actually developed, they occur as pui-ely secondary, or rather, tertiary developmental changes in the ephebic stage. This fact is of importance because of its bearing u})on the biology of Ammonitinte in the Cretaceous. With regard to these, it may be stated that they are distinctly tachygenetic or accelerated in development when "Inferior Oolite Ammonites: Palseont. Soc, Vol. II, pp. 40-49. *Pal. Mittheil., pi. 4. ^■Amm. (1. schwiib. Jura, pis. 24, 69. 19 20 PSEUDOCERATITES OF THE CRETACEOUS. compared with the Ammonithise of the Jura. All of the forms so far inves- tigated, which have more than one principal lateral saddle and lobe, acquire these characters a stage earlier than the Jurassic species. They appear, as stated above, in the neanic stage and are secondary modifications of the outlines of the primitive first laterals of the nepionic stage. The same law seems to hold in a modified way for the development of an extra unmber of auxiliary lobes and saddles such as appear in Ncumayria, but my materials have not enabled me as yet to follow this out. This statement appears at first sight to be antagonized by that made with reference to the arrested development of the sutures in genera like Protengonoceras, Engonoceras, etc., which have undivided or bifid saddles and lobes only slightly digitated at their extremities. But it will be shown in the generic description of Placcnticeras that the arrest of development takes eff"ect in these Pseudoceratites of the Cretaceous only after the three principal lateral saddles and lobes are formed in the neanic stage. Consequently, up to this stage, the development is more complex than in the young of Jurassic species or any others which have only one principal lateral at the same age. This statement clears up the extraordinary relations of these forms to their apparently more complicated allies of the Jurassic, and accounts also for the apparent discrepancy existing between the highly involute compressed character of the whorls during the neanic stage and the very simple aspect of the lobes and saddles; that such highly involute compressed forms in the Jura, usually combined with the development of highly complex lobes and saddles, has been recorded by me in other papers and Ijy many other writers; consequently, when one meets the Pseudocera- tites of the Cretaceous he is apt to imagine them to be what Barrande has called "anaclu-onisms," and difficult problems for the evolutionist. They are unquestionably difficult, but they are no more anachronic than any of the forms usually named as having this paradoxical character. They are simply excellent examples of arrestation of development taking efi"ect locally and upon certain structures. These, if 1 have rightly understood the researches of my deceased friend. Professor Cope, the most brilliant investigator and profoundest thinker on evolution that America has pro- duced, are good examples of his law of retardation in development, and also excellent examples of the difterent way in which I look upon the same phenomena. I have never regarded such cases as examples of a tendency GENERAL REMARKS. 21 to retardation of development. A distinction exists between arrestation and retardation in development, winch is of great importance. Arrest of development occurs in many ways. It may take effect locally, as upon the sutures, stopping- them from developing in complexity of outline beyond a certain measure, and thus retaining a semblance to their own young and apparently reverting to the condition of the same parts in more ancient animals of their own stock. It may take effect upon the whole organism, as in BacuUtes and other uncoiled forms, apparently causing the entire animal to revert in its characters to a primitive form. There are imuimer- able degrees between these two extremes which it is not necessary nor appropriate to mention here. Retardation is distinct from these and of much rarer occurrence. " The development can not be said to have been retarded in these retrogressive forms, since it begins and for a certain period in the ontogeny progresses in jiarallel lines with the ancestors of the group, but passes through the modifications more quickly according to the law of tacliy- genesis. After this its progress is quite suddenly and decidedly arrested, and the succeeding stages are no longer parallel with those of their ancestral forms. The complexity of the outlines of the lobes and saddles in species of Engonoceras, for example, does increase even in the later stages; but this increase is very slight, and the result is a retrogressive form that mimics to a certain extent jwimitive forms among Goniatitinse and Ceratitinse. Such examples may, nevertheless, belong to the highly accelerated class, as is shown by the earlier development in these Pseudo- ceratites of the Cretaceous of the three principal saddles that only appear in the ephebic stage of the highly progressive forms among Annnonitinaj of the Jura. Retardation of development certainly does not take place in their early stages. Can it be said to take place because they do not subsequently jjroceed to develop numerous marginal lobes and saddles on the borders of these same lobes and saddles'? Retardation of development can mean but one class of phenomena, viz, those cases in which a character appears in the ontogeny of descendants later than the stage at which it appeared in the life of their ancestors. In cases of retrogression such as are noted above, and in all examples of this class with which I am acquainted, the complication of the lobes and « Bioplastology and related branches of biologic research; Proc. Boston Soc. Nat. Hist., Vol. XXVI, p. 79, etc. 22 PSEUDOCEKATITES OF THE CRETACEOUS. saddles by the addition of marginals during the later stages of the ontog- eny does not occur; the inexact parallelism is produced by the dropi)ing out of this stage completely, not by its later and later development. Cope, in his great work Origin of the Fittest, writes as follows:" * * * The acceleration in the assumption of a character, progressing moro rap- idly than the same in another character, must soon produce, in a type whose stages were once the exact parallel of a permanent lower form, the condition of inexact parallelism. As all the more comprehensive groups present this relation to each other, we are com- pelled to believe that acceleration has been the principle of their successive evolution durino- the long ages of geologic time. Each type has, however, its da^- of supremacy and perfection of organism, and a retrogression in these respects has succeeded. This has, no doubt, followed a law the reverse of acceleration, which has been called retardation. By the increasing slowness of the growth of the individuals of a genus, and later and later assumption of the characters of the latter, they would be successively lost. To what power shall we ascribe this acceleration. l>y which the first begin- nings of structure have accumulated to themselves through the long geologic ages complication and power, till, from the germ that was scarcelj' born into a sand lance, a human being climbed the complete scale and stood easily the chief of the whole? * * * Acceleration signifies addition to the number of those repetitions during the period preceding maturity as compared with the preceding generation, and retarda- tion signifies a reduction of the numbers of such repetitions during the same time.* Thus, from Cope's point of view, tachygenesis is the law of progression, and retardation is the law of retrogression, and they are both essential parts of his law of acceleration and retardation. These qi;otations show that we both have the same conception of the proper use of the word "retardation," but we differ in the application of it. He applied it to such cases as are described here among Pseudo- ceratites, whereas I regard these as true arrests of development and not as retardations. Retardation is exceedingly rare among Anmionitinse, and as a rule in other parts of the animal kingdom, and the only examples I am able to cite are like those given below in Placentkeras, where the more complex species like ivhifJiehU, that are obviously descended from species like P. syrtale, liave apparently the nodes and ornaments smaller and developing, as a rule, ]at(-r than in that species, and iinall}', in extreme forms like those of typical ivhltfieldi, disappearing altogether. «P. 142. ''P. 182. GENERAL REMARKS. 23 As a rule, among Ammonitinae the reverse is the case, and the disap- pearance of characters takes place through the earliei' and earlier develoj)- ment and shorter and shorter life history of each characteristic, or through tachygenesis, as stated and illustrated in many of my papers. Here I have space only for one quotation, which will serve to show my meaning more plainly : Specialization by reduction of parts is evidently included under the head of retardation by Cope; thus in Oi"igin of the Fittest (p. 353), he says that ''change of structure during growth is accomplished either by addition of parts (acceleration) or by subtraction of parts (retardation)." So far as my experience goes, in the major number of cases the parts or characters that are undergoing reduction disappear according to the law of tachygenesis. They reappear in the ontogeny at earlier and earlier stages, or exhibit this tendency in the same way as characters of the progressive cla.ss, but their development is not so complete as in ancestral forms. In this sense they can be regarded as retarded or thrown back in their development. There is, however, another way of formulating the expre.ssion of this. Instead of regarding this disappearance by retrogressive gradations as due to a tendency opposed to acceleration, is it not a tendency- of the same kind? That is to say, do not the parts and characters show a tendency to disappear earlier and earlier, and are the}' not in most cases at the time of disappearance present only in earlier stages of growth than that in which they originated in ancestral forms? Is not the case of the wisdom teeth exceptional? The frequently extremely late external appearance of the.se is not accompanied })y a later origin of their rudiments in the jaw. Although they may not appear in many cases above the gum until a person is past iif ty, is not this real retardation due primarily to the fact that they are deficient in growth power (tending to disappear from disuse, etc.), and secondarily to their internal position? When they cease to be able to break through the gum will they not still continue to develop at the same stage as the other teeth, and will not their rudiments be likely to be present at this early stage long after they have ceased developing into perfect teeth ?<* The whalebone whales are examples of this kind so far as the teeth are concerned, although here the disappearance is correlated with the develop- ment of whalebone from the rugae of the roof of the mouth. Nevertheless the suppression of the teeth in full-grown animals does not take place bj' later and later development, and the rudiments of the teeth are still present in the early stages. "Biopla-stology; Proc. Boston See. Nat. Hist., Vol. XXVI, note to p. 80. SYSTEMATIC DESCRIPTIONS. This group in my chapter on Cephalopoda in Zittel's Text-book con- tained a number of keeled families, in which either the keel was preceded by a median line of tubercules, or, if this stage were omitted, the smooth keel arose upon the venter in forms that were apparently closely allied to the more primitive genera having these tuberculated keels. The Mam- mitida included Mammitidte, Peronicei-atidse, Prionotropidpe, Hystato- ceratida?, Lenticeratidne, and Tissotiidse. To these I propose to add now the Mojsisovicsiida?, Buchiceratidse, Pseudotissotiidse, Eulophoceratidse, Sphe- nodiscidte, and Coilopoceratidse. MOJSISOVICSIIDiE Hyatt. The single genus and species described below can not be even pro- visionally included in any of the gi'oups to which it is supposed to be nearly related, and the following discussion of its generic affinities shows this conclusively. The dorsal futures are not yet known, and this is the only defect in the evidence that establishes it as an independent group, probably belonging to the parent stock or stem of the Pachycampyli. MOJSISOVICSIA Steinmann. The interesting species used as the type of this genus has a form which is similar to that of Agassiceras of the Lower Lias in being smooth and discoidal, with flattened sides, narrow umbilical zones and rounded venter. The section is what I have called helmet shaped, like Acjas. striar- ies. It differs in having no raised line or keel, and therefore comes a little nearer to Psiloceras. The sutures bear a similar interpretation, since, although these are very immature, there are four lateral bitid saddles with "A penciled note at the top of this page of manuscript says "Revise list." Just what changes the author would have made can not be known, but it may V)e inferred that Lenticeratiihe was dropped as an aV)andoned family, and that possibly C'(>ilo[)oceratidie was assigned to another super- family. It is obvious that his conception of the group Mammitida had become very different from that expressed by him in Zittel's Text-book. — T. W. S. 24 MOJSISOVICSIID^. 25 siibpliylliform marginal saddles and excessively short pointed marg-inal lobes that are hardly more than serrations. The ventral lobe is very broad and divided. The tirst and second lateral lobes are narrow and similar to tliose of BucMceras, bnt it should be noted that the dorsal sutures are unknown, and these may l)e quite distinct. The third lateral lobe is entire, and the fourth saddle hardly past the entire stage, exhibiting only a slightly triiid outline. Such sutures exhibit affinities with the smooth primitive ancestral stock of the Psiloceratidfe of the Jura and other forms of Pachy- campyli descended from these because of their massive broad saddles, so entirely different from the narrow, excessively branched saddles of the Phyllocampyli ami Leptocampyli. I do not, of course, mean that Mojsiso- vicsiu is probably descended directl}^ from Psiloceras, l)ut it may be a Cre- taceous member of a primitive stock which began with Psiloceras in the Jura. The intermediate forms are as yet unknown or have not been pul)- lished. The existence of such a trunk or main branch of a primitive stock from which all of the more complex groups are lateral offshoots has been inferred from the ontogeny as the most probable way to account for the ontogeny of the primitive species of these groups. Thus in the present instance the smooth discoidal young of Buclikeras and other genera can be readily accounted for if the comparison between tliem and the later stages of Mojsisovicsia is admitted. If such a stock of primitive forms existed, it is also easy to account for the maintenance of such primitive smooth psilo- ceran-like shells in the later nepionic and sometimes in the neanic stages of Cretaceous fonns Otherwise the continued renewal of these in the ontos"- eny at such late stages must be referred to more ancient ancestors than any rej)resented in the Jura. Mojsisovicsia durfeldi Steinmann. PI. I, figs. 1-3. Jfojs/'sovicsia durfvldl Stcinmiuin, Neues Jahrbuch fiir ]Min., Geol., unci Pal., 1881, 11, p. 143, pi. 6. The pecuhar fossil described under this name has a compressed discoidal shell with slight constrictions, open umbilici, and smooth surface that in external aspect resembles Traneceras and also some of the discoidal Desmo- ceratidff like Pseudophyllites Kossmat, but has entirely different sutures. These liave an asj^ect similar to those of Buchiceras hilohatuiii, but the form of the AM)lution differs so widely that no further comparisons can be itiade 26 PSEUDOCERATITES OF THE CRETACEOUS. with this genus. The living oluimber is short, the aperture lias a l)huit rostrum, there are shallow sinuses on the edges of the venter, a Inroad lateral rostrum on either side, and shallow sinuses between these and the umbilical shoulders, and probably a crest on the dorsum. The ventral lobe is very broad and short, with a broad short siphonal saddle. There are three bifid lateral saddles, with an incomplete apparently entire saddle at the line of involution. The lobes are short and much narrower than the saddles, and the entire outlines of both lobes and saddles have short obtuse marginal saddles and narrow, short, pointed, simple marginal lobes. The species is known to me only through Steinmann's figures, wliich are reproduced on PI. I, figs. 1-3, with the single exception of his enlarged drawing of the side view of fig. 1. Locality: Pariatambo, Peru. Age: Albian (?). BUCHICERATID^ Hyatt. It has been found impracticable to unite the genus Buchkeras with any known family, on account of its peculiar development and sutures. The approximation to the rlystatoceratidse. is close, so far as the earlier stages are concerned, the compressed, comparatively smooth-keeled young in the neanic stage having considerable resemblance, but these similarities are lost in the subsequent developmeiit, owing to the partial suppression of the costse and the very distinct sutures. The development and sutures separate these forms completely from Kncmiceras. They are separable from Tissotiida? by their first lateral saddles and their ventral lobes, and from Barroisiceras, which they also resemble, by the absence at all stages of a third line of tubercles and by their sutures. The sutures are similar to those of the discoidal smooth shell of uncer- tain affinities described as Mojsisovicsia by Steinmann. So far as known there are no representatives of this genus except in South America. It slioidd be remembered, however, that all information heretofore published has cimie from this single fossil. The second genus included in this family, Roemeroceras, has similar ventral lobes and siphonal saddles, and the young, although (juite distinct in l)eing less compressed in the early stages, acquire a similar keel at a later age, and similar form and ornaments. BLTCHICERAT1D.E. 27 BUCHICERAS Hyatt. This genus was formerly described V)y mj^self as including- several different species that have since been separated into distinct genera, by Douvilld, Grossouvre, and others, and by myself, iu Zittel's Text-book of Paleontology. The affinities of Buchiceras are not, in ray opinion, very close to any of the forms formerly referred to Acanthoceras as supposed by some authorities. The sutures are quite distinct from those of any of the families of Mannnitida on account of the extraordinary breadth of the second lateral saddles. The development is similar to that of some forms of Hys- tatoceratidfe and Peroniceratida? in that it is at first discoidal, compressed, and smooth, then keeled, becoming costated and tuberculated later, and the sutures approximate more closely to those of the young of these families perhaps than to others. Nevertheless the ontogeny differs in that Buch- ireras does not subsequently acc^uire prominent costa?, and the keel tends to disappear instead of becoming larger with increase in size of the volutions. The nodes, on the other hand, increase in size and prominence, especially the inner row on the umbilical shoulders. The faint sen-ations on the keel and other ornamentation suggest affinities with Barroi steer as, but the sutures and the absence of a third line of lateral tubercles, which appear in some forms of Barroisiceras, are not favorable to this solution of the affinities. The same objections apply almost equally to keeled forms of the Prionotropidae in which the young resemble more or less closely those of B. Ulohatum. The dorsal sutures are very remarkable and perhaps may eventually assist in placing this genus in closer connection with others. The primitive first lateral saddle is retained in Buchiceras until a late stage, and perhaps throughout life ; it is undivided, except by small entire marginal lobes, but it is distinctly bifid. Buchiceras hilobatum Hyatt. PI. I, figs. 4-y. Buc/t/'ce^w hllulatum Hyatt, 1875, Proc. Boston Soc. Nat. Hist., Vol. XVH, p. .37u. Buchiceras hllobatum Douville, 1890, Bull. Soc. geol. France, 3d ser., Vol. XVIII, p. 284. The young, for the first two, and perhaps part of the third volution, must have had smooth sides and was obviously very discoidal, flat, and keelless. The aspect of this species must have been very similar to Mojsi- sovicsia. The keel comes in upon an elevated venter previous to reaching 28 PSEUDOCERATITES OF THE CRETACEOUS. the diameter of 5 inin. and is faintly sinnous during tlie latter part of the volution seen in PI. I, fig. 4. These faint undulations are due to prolonga- tions of the costfe that pass between the tubercles on the ventro-lateral angles. This keel, which is a mere angle on the venter, was obviously continuous before the costaj appeared and is practically continuous sulise- quently, owing to the minute character of the inflections. Upon the last of the outer volution at this diameter, the first of the fourth volution, the outer line of tubercles appears and is connected by costse with the inner line. The last are very widely separated at first and become nearer only in later stages. The larger costse at this age are separated by single, arcuate costa- tions terminated outwardly by minute tubercles and fading out internally about halfway across the volution. The umbilical zones are not diff"erenti- ated from the sides. The side is evenly plano-convex from the keel to the line of involution and the inner, uncostated part is smooth, excejit where interrupted by the inner tubercles or extensions of the tubercular termina- tions of the larger costse. The tubercles and nodes are opposite, not alternate. The sutures at this age consist of two large saddles (PI. I, fig. 9), a narrow first lateral lobe in the center of the lateral zone and a broad second lateral on the umbilical zone. The inflections are all apparently entire. In succeeding stages the lobes remain in the same position, there being but one in the center of the side between the two rows of tubercles and one on the umbilical shoulder, but as the shoulder becomes more prominent and the umbilical zone broadens, other lobes and saddles appear internally. The venter broadens Avith age, the keel becoming more obscure in consequence of this; the sides become flat and convergent ; and the umbilical shoulders broaden out more than the venter, the increase in the umbilical zones making the umbilici very deep. The keel on the cast at this mature stage is faintly undulated, and the lateral eostje, although very obscure, cross the venter and inteiTupt the keel between each pair of opposing ventro-lateral nodes. These widely separated serrations are so faint on the cast that they entirely escaped my observation on former occasions. They in fact can be felt more easily than they can be seen. This is also the case in the earlier stages described above. The inner nodes are always larger and fewer than those on the edges of the venter. The second lateral saddle remains broader than the first lateral, even when the shell is somewhat over 40 mm. in diameter. It occupies a trifle more than half of the side and encroaches on the umbilical zone (PI. I, fig. 8). BUCHICERATID.E. 29 The ventral lobe is very widely open at the base and long-er than tlie first lateral lobe. The two arms are blunt and ver}' small. The siphonal saddle is phenoraenallv short and broad, with a faint centran marginal lobe and an equally faint marginal rounded saddle on either side. The first lateral lobe is funnel shaped, broad at the base, short and narrowing rapidly to a bifid termination. Tlie second lateral lobe is very much smaller and shorter, and entire at the end. The third lateral saddle is small, entire until a late stage, but becoming bifid later. Beyond are two small entire saddles and two corresponding lobes or what may perhaps be more accurately described as a bifid lobe and a bifid saddle. The first and second lateral saddles have internal ridges, but these coalesce, forming- a short, flattened area along the mesal plane, which becomes deeply convex toward dorsum and venter. There are only two broad saddles and two naiTow lobes on the dorsum, and these have no connecting ridges Avith the external saddles. The surfaces of the wings of the septa are strongly inclined inward, the outer sutures being considerably in advance or orad of the inner ones. This gives a remarkably concave aspect to the wings of the septa on either side of the dorsum. The dorsal sutures, which were woi'ked out Avith difficulty, show that the inner arm of the bifid fourth lateral saddle passes across the line of involution, coalescing with the third dorsal saddle. The antisiphonal lobe is asymmetrical, entire at the top, unequally serrated on the sides, and bent over to the left until the tips touched the inner angles of the first pair of dorsal saddles to the right of the mesal plane of the body. The first pair of dorsal saddles are deep and broad with broad entire bases. The first lateral lobes are small and unequally bifid, the sides being coarsely serrated. The second dorsal saddles are much inclined and obscurely tridentate or entire. The second dorsal lobe is very small and entire. The third dorsal saddle is a part of the fourth lateral, as stated above, and is entire. Vestiges of the shell were present upon this cast in a few places and showed coarse lines of growth. Unfortunately the shell covering the venter f)f the young whorl w^as chipped off in cleaning this part for drawing, and evidence of the statement made above with reference to the keel was lost. Locality: Cachiyacu, west side of Hullagua River, Peru. Age: Upper Cretaceous. 30 PSEUDOCERATITES OF THE CRETACEOUS. ROEMEROCERAS Hyatt. These shells were so similar to the type of BiicMceras in external aspect that I formerly supposed the type of this o-enus to be an older stage of B. bilohatum, but more prolonged acquaintance with these forms shows that they are not in the same generic group. While the bifurcated costfe, the large nodes on the umbilical shoulders, and the nodes on the ventro-lateral angles are the same, the involution is greatei", the lateral zones more com- pressed and broader, the umbilici narrower, the young have larger nodes, and the keel entirely disappears in the full-grown shells, except perhaps in R. (jabhi. The sutures are also quite distinct, and similar to those of Tisso- tidse in some species, but the first latei'al saddles tend to develop three arms in some species and the leases of the other saddles are apt to be dentated more or less completely. The ventral lobes are similar to those of Buchi- ceras and entirely distinct from the broad veutrals of the Tissotiidai. The same characters appear to unite Knemiceras with Roemeroceras, but the development and full-grown shell in Knemiceras, especially the invariable presence of the concave venter, seemed to place it in closer association with the Pulchelliidse. RoEMEROCEKAs GABBi n. sp. Hyatt. PI. 11, %s. 1-3. Ammonites hilobatu^ Gabb, 1877, Jour. Acad. Nat. Sci. Philadelphia, 2d .ser., Vol. VIII, p. 270, pi. 38, fig. 3. In my i-evision of this form I made too great allowance for the possible variations due to age, and misled Professor Gabb in identifying this fossil with Buchiceras hilobatum. As compared with B. bilobafiDii, the nodes on the umbilical shoulders are much less prominent and more numerous and more closely approximated, the venter has large ridges not present in bilobafuiii, and the flatness and proportions of the saddles are too distinct to occur in the same sjjecies, even though allowance be made for the sutures in f/abbi being nearly one volution older than those examined in B. bilobatum. The sutures of this species approximate more closely to those of R. syriaciforme than to those of any other species, but R. f/abbi differs in the greater numljer and smaller size of the nodes and costfe. Fig. 3 of Gabb's plate shows the lateral aspect with an outer line of nodes lower on the sides and a sinuous outline to the venter which does not appear ni syriaciforme, and also a BUCHICERATID.E. 31 stouter and more quadrag'oiial volution than any other species of this genus. The originals of this species were not reexamined. They could not be found in the Academy's collection at the time of m^- visits, nor has subse- quent search, made by the kindness of Professor Pilsbrv, brought them to light. LocaUhj: Quebrada de Colpamayo, Department of Cajamarca, Peru. Aye: Upper Cretaceous. ROEMEROCERAS SYRIACIFORME Hyatt. PI. I. figs. 10-14. Eoetnei'oceras ^yriaciforme Hyatt, 1875, Proc. Boston See. Nat. Hist., Vol. XVII p. 371. This species reaches a diameter of 90 mm. in one cast without a living chamber. The sutures ai-e approximated and overlap internally on the auxiliaries, showing that the geroutic stage has begun. The ornamentation and form are the same as in bilohatuin. When the cast is only 29.5 mm. in diameter there is, however, no difficulty in separating this from bilohatum. It is more compressed, the sides broader, the venter narrower and flatter. The sutures have more resemblances to those of R. (/ahbi, but the saddles and lobes are never so short, nor truncated, the saddles being narrower and the lobes broader. The ventral lobe and siphonal saddle are similar, but narrower and less digitated. The first lateral saddles are similar in being bifid and rather broad, but already at this early stage sho^v denticulations over the entire base. The first lateral lobe is similar but less deeply divided, by the similar marginals. The second lateral saddles are unequally bifid s\'ith bases rounded or approximately phylliform, entire, and unlike those of (/ahbi The second lateral lobes are quite broad, a])ically like the first laterals, but are unequally quadrifid. The third lateral saddle is as broad as the second lateral, and also l^ifid. It occupies part of the side and also part of the umbilical zone, the marginal lobe being upon the umbilical shoulder. Inside of this there is one broad bifid saddle reaching to the lobe at the line of involution. There are therefore four saddles at this early stage very like those of yabbi, except in having rounder bases. Later, on the same volution, this inner saddle becomes divided into two by a median marginal lobe, and still later a small lobe makes its appearance at the line of involution, completing the outline of the innermost lateral saddle. There are then five saddles and six zygos lobes on either side. 32 PSEUDOCEKATITES OF THE CRETACEOUS. The oldest svitures are very much changed, and look like those of a distinct species, but are obviously in the gerontic stage. The bases of the saddles are nearer together, the entire parts of the sides much elongated, and the lobes longer and narrower and the dig-itations situated at their apical ends nuich deeper. The saddles are longer and broader, with entire bulging sides, and the marginals not increased in number, but much longer and larger. The sutures have at this stage close similarity to the peculiar outlines attributed to Ammonites syriaciis by von Buch (fig. 1 of pi. 7 in his Uber Ceratiten), but the first lateral is not so broad and does not have the minute jjhylliform marginals of that figure. The marginals on the first lateral saddles, and also in the first lateral lobe, are tongue shaped. The fourth and fifth lateral saddles are entire, tongue shaped, and divided by a narrow bifid lobe. The young sutures, until a late neanic stage, have outlines similar to those of some species of Tissotia. After this the outer saddles become completely denticulated, and again, as described above, lose a considerable part of these denticles in old age. Fragments of the shell were present on the largest cast. None of the specimens was incrusted by any extraneous growths that could be shown to have fastened themselves on the surfaces of the casts. The figure of the young in an early ephebic substage (PI. I, fig. 12) is a very near approach to the old specimen which was crushed on one side (PI. I, fig. 10), but of course, owing to difterences of age, the nodes are larger." There are fifteen nodes on the ventral border and six on the umbilical shoulders on one volution of the younger specimen, and eleven on the outer and seven on the inner row of the old specimen. The bifid costfe are also present in the younger specimen, mingled with single ones, as in the old stage. The keel disappears on the last quarter of the outer volution, both on the cast and on the shell, in the young specimen, and is absent also in the older one. The young shell was seen in a section of the specimen represented by fig. 12 of PI. I, and although not perfect enough to figure, showed that when about of the same size as the young of B. hilohatum (PI. I, figs. 5, 7), it had a similar keeled form. Locality: Cajamarca, Peru. Age: Upper Cretaceous. "See also description of /r . if that species, as first pointed out by Peron. Choffaticeras, until a late age, has a venter with keel and channels like those of Pseudofissotia in C. meshi but combined with an inflated volution and deep, abrupt umbilici and highly inclined, convergent sides. In other species the line of modifications indicated by the later stages of its ontogeny leads into forms having subacute venters at a comparatively early age, and possibly the keeled and channeled stage with its flat venter may have altogether disappeared in some of these. The highly involute, comi)ressed- keeled forms of Hemitissotia follow these in the same line of modification and as their sutures also coincide and they occur in the Senonian, whereas all of the above-described genera are Turonian, Peron's idea that they are the direct descendants of Pseudotissofki seems to be well sustained. That these are not transitional to true Tissotia becomes apparent when It IS recognized tliat tlie type form of tliat genus has an ontogenetic history like that of PseudotissoHa and is probably, as stated in the description of the Tissotiida", the most primitive member of a series of forms distinguished by their differences of development as well as by tlieir simpler and more retrogressive sutures. Although the sutures differ decidedly, the forms of more i)rimitive species like Pseadotissotia yallienmi and their keels appear to place thein provisionally nearer to the Buchiceratida? than to the keelless forms. I have had no fossils for examination in this family, but the literature and the figures given by Grossouvre and Peron have been sufficient to enable me to arrange the forms provisionally and to make connnents upon their probable relations that will, it is hoped, attract attention and lead those who have better opportunities to test the truth of the views presented below. PSEUDOTISSOTIA Peron. Peron's typical species, Ps. fjaUiennei, is a discoidal form with keel and channels, having obviously, as observed by Peron, genetic affinities with 36 PSEUDOCERATITES OF THE CRETACEOUS. true Tissotia as here defined, but it differs in the more complex outHnes of the sutures, all of which have small marginal lobes and saddles. In my opinion, the genus should be limited, so far as known, to one species, the type described bv Peron. The other species described under this name are obviously widely distinct in their forms and mode of development. The sutures resemble those of Boemeroceras on the lateral aspect. The ventral lobes are also alike, so far as can be seen on Pei'on's figure. Peron's sug- srestion that these are the ancestors of Tissotia and its allies in the Senoniau appears to be supported by the facts so far as now known. They appear also to have been the immediate ancestors of Henutissotia and its allies iu the Senoniau, but this last inference needs confirmation that can only be obtained through the study of the young of the latter. PSEUDOTISSOTIA GALLIENNEI (d'OrljigUy). Psmdotissotia gallimnei Peron. 1896, Mem. Soc. geol. France. Paleontologie, Vol. VI, No. 17. pi. 2. tig. 3: pi. 3. tig. 1. This is a moderately compressed but still comparatively discoidal form, with large umbilicus and involution enveloping something more than one- half of the sides, according to Peron's figures. The venter is flattened, with heavy, continuous keel and shallow channels bordered externally l)y thick continuous ridges. The sides have very broad fold-like costae with- out tubercles. In extreme age all of these ornaments disappear. The entire aspect and genetic transformations of this fossil are so similar to those of Tissotia tissoti that it would have to be included in the same genus, if the sutures were unknown. Locality: France. Age : Turonian. PsEUDOTissoTiA '? TUNisiENSis n. sp. Hyatt. Tissotia cf. fourneli Peron, 1896. Mem. .Sue. geol. France. Paleontologie, \o\. VI. No. 17, pi. 12, tigs. 7, 8. Tissotia fournel ! Peron. 1890, Moll. Cret. de la Tunisie. ])1. 17. tigs. 11-18. This remarkable fragment has a truncated ventei", entire keel, and compressed volution, with moderately large umbilicus. The costte are fold- Hke, with tubercles on the umbilical shoulders and a line of closely set elouffated tubercles on the ventro -lateral angles. The first lateral saddles are trifid and rather peculiar, owing to the approximate equalit}' of the tliree PSUEDOTISSOTIID.E. 37 marginal saddles. The other saddles are very long- and phylHfonn, and according- to Peron's tig-nres the third saddle is tritid or bifid. These sutures and the ventral lobe, with its steep denticulated sides and truncated siphonal saddle, are similar to the sutures of the old stage of Roemeroceras syriaciforme. The form and ornamentation also agree with this determina- tion, but the keel is more prominent than is usual in this genus. It is pos- sible to understand this form, if it is related to Ps. (jaUiennei, because in that case the keel and lateral costse are similar to those of that species. The differences in sutures lie largely, according to Peron's figure, in the second lateral saddles, which are entire. This mav be due to retroo-ression. Locality: North Africa. Age: Santonian. CHOFFATICERAS n. gen. Hyatt. This genus has sutures similar to those of Pseudotissotki, but the form is distinct. The species are more or less stout gibbous forms with more or less open and deep umbilici. The sides are heavily costated and nodose along the umbilical shoulders, but there are no external tubercles according to Peron. He also describes the venter as liaving a continuous keel and two ventro-lateral ridges. The form is more involute and more compressed than Pscudotissotia, and the outer parts of the volutions have a tendency to become concave in the involute species with broad volutions. The type is C. meslei (Peron). (Jhoffaticeras barjonai (Chofiat). Pseudvtlsiiotla haijoaal Choffat, 1898, Faune Cret. du Portugal, Vol. I, 2d series, pi. 18, fig-. 3; pi. 22, figs. 40-42. This species is a close ally of C. meslei of North Africa, as has been stated by Choffat, l)ut has a more i)rominent keel and has no signs of channels on the venter. Locality: Portugal. Aye: Turonian. Choffaticekas meslei (Peron). P^cudotlnxutlii iiiKsIel Peron (i^ars), 189ij, Mem. Soi-. geol. France, Paleontologie, Vol. VI, No. 17, pi. 1, fig-. 1; pi. 2, fig. 1 (not pi. 2. fig. 2. nor pi. 3. fig. 2). This species has a form which is sublenticular when seen from the front in Peron's figure, owing to tlie great prominence of the umbilical 38 PSEUDOCERATITES OF THE CRETACEOUS. shoulders and the rapid wlope of the latei-al zones and subacute character of the venter. Tlie costaj are hnear and only slightly curved in the nnly well-preserved part of his type as fio-ured. The involution covers about three-fifths of the next inner whorl, leaving- a rather large open umbilicus showing the younger whorls. The more discoidal form (\A. 2, fig. 2, and pi. 3, fig. 2) supposed to belong to this species, is certainly distinct specifically and may be nearer to Pseudotissotia tlian to any species of this genus, but it is too imperfect to g-ive diag-nostic characters. Locality: North Africa. Age: Tnronian. Choffaticeras ? DOuviLLEi (Peron). Pseudotissotia douvillei Peron, 189*;, jNleiii. Soc. geol. France, Paleontologie, Vol. VI, No. IT, pi. 2, figs. 4:, 5, and pi. 3, figs. 3, 4. This species, as figured and described by Peron, has the general form and aspect of C. meslei, but the heavy nodes on the umbilical shoulders and dichotomous costai reaching to the sides of the prominent keel are quite difierent. Locality: North Africa. Aye: Tnronian. HEMITI8S0TIA Peron. This "enus seems to me to be more intimately related to Choffaticeras than to Tissofia and other genera having similar forms lint having sutures with smooth saddles. Such questions can only be definitely settled when the younger stages become known. These involute and more or less com- pressed forms with trenchant keeled venters are apparently in the direct line of modifications indicated by the sinnlar forms of Tissotida?, but on the other hand their sutures correlate with the more complex outlines of those of Psendotissotia and Choffaticeras, and this indicates that the}- are simply parallel as representative forms analogous to some of tlie Tissotidse but reall}' in the genetic line of Choffaticeras. They have retrogressive characters in the undivided outlines of their inner saddles, but this arrest of development has not affected the outer saddles that are completely dio-itated. They can not be placed anywhere in the genetic line lietween Pseudotissotia .and Subtissotia on account of the absence of channels and PSEUDOTISSOTnD.E. 39 ridges on either side of the keel, and tliis is the only position that could be claimed for them in view of their peculiar sutures. All of their characters accord best with the view that they are direct descendants of Choff'aticeras. There is an interesting- group of this or an allied genus from the Senonian, described by Chotfat in liis Cephalopodes de la Faune Cretacique du Portu- gal, Vol. I, 2d series, but the condition of the specimens did not permit him to describe them sufficiently to judge closely of their affinities. Hemitissotia cazini Peron. Hemitissotia cazini Peron, 1897, Mem. Soc. geol. France, Paleontologie, Vol. VII, No 17, pi. 14. tigs. 1-5; pi. IS, figs. 9.10. This species is a highly involute compressed form, and in the oldest specimen tigured the first and second lateral saddles are completely denticulated, the third is equally divided by a median marginal lobe in the figure of the suture of the oldest specimen (pi. 18, fig. 9), but this is not described in the text. Locality: North Africa. Age: Senonian. Hemitissotia? batnensis Peron. Hemitissotia? hatnensis Peron, l.S!)7. Meiu. Soc. geol. France, Paleontologie, Vol. VII, No. 17. pi. l.T. tigs. 7, s. This species has the external aspect nf this peculiar group and the sutures are similar as figured by Peron, but his question mark after the generic name is justified by the S2)henodiscus-\ike aspect of the first lateral saddles. Locality: North Africa. Age: Senonian. Hemitissotia morreni (Coquand). Hemitissotia morreni Peron (pars), 1897, Mem. Soc. geol. France, Paleontologie. Vol. VII, No. 17, pi. 15, figs. 1 and 2 only, and pi. is. tig. 11. neiiiitinsotki morre^ii v&T. prsecipua, ibid., p. 77. This var. prcecipua of Peron is a highl}' compressed form with acute venter. PI. 15, fig. 8, may be the young of this species, and if so, it shows conclusively that it is distinct from the following. Locality: North Africa. Age: Senonian. 40 PSEUDOCERATITES OF THE CRETACEOUS. HeXIITISSOTIA TISSOTI.EFORMIS Peroii. ILiidtisHotla morreni var. tmot'neforiiili< Peron, 1897, Mem. Soc. geol. France, Pal^ontologie, Vol. VII, No. 17. pi. 15, figs. -3-5 only. This i.s a much stouter form with stouter volutions, and as might lie expected in such a species the young exhibits distinct ribs. Hemitissotia morreni var. coquandi (pi. 15, fig. 6) may be distinct, but no front view is given and the sutures shown in pi. 18, fig. 14, do not appear to be very different. Locality: North Africa. Age: Senonian. Hemitissotia d.ielfensis (Peron). Tissotia djelfemis Peron, 1897. Mem. Soc. geol. France, Paleontologie, Vol. VII. Mo. 17, pi. It), figs. 3, 4. Buchiceras ewaldi (pars) Peron, i8yiJ, Moll. Cret. de k Tunisie, pi. 15, figs. 7 and 9 (no others). This is a compressed shell very closely allied to Paratissotiajicheuri in aspect, but differing in the sutures. These have the first lateral saddles narrow and bifid as in Hemitissotia and the first lateral lobe is large as in that genus. The figure of the highly compressed cast given by Peron as part of his ewaldi in the MoUusques Cretace de la Tanisie has very similar sutures so far as the deep division of the first lateral saddles and lobes is concerned. It is better to quote it here, since it is undoubtedly not related to tlie other species on the same plate and has also a form similar to that of djelfensis. Locality: North x\frica. Age: Lower Senonian. Hemitissotia ceadouroensis Choffat. Hemitissotia ceadouroemis Choflat, 18!»8, Faune Cret. du Portugal. Vol I. 2d series, pi. 20, tigs. 7-10. This species is apparently a member of this genus and is of interest in sliowing the old-age transformations, the rounding of the venter and contraction of the outer volution. If the last part of the last volution is perfectly natural, it shows an extraordinary senile scaphitoid deviation from the spiral. Locality: Portugal. Age: Senonian. PSEUDOTISSOTIULE, TISSOTIID.E. 41 PLESIOTISSOTIA I'eron. This g-enus lias been founded by Peron entirely upon tlie diti'erences of the sutures as compared with HeinUissot'm. The fii'st hxteral saddles are broad and very deeply divided by a median maro'inal lobe and each arm is plivlliforin and is also subdivided by a median marginal lobe; the remaining saddles are phylliform and equally subdivided by median marginal lobes. It is a question whether these peculiar sutures really represent another group or are simply retrogressi^'e modifications in the genetic line of Heinitissotia. The compressed and costated form does not indicate affinities, but, as stated by Peron, the divided saddles are similar to those of Hemitissotia prcBcipua, except the first laterals, which are narrow and irreffular in outline in the latter. ^e Plesiotissoti.1 michaleti Peron. Ple-sintlssotui iiiichaJcti Peron, 1SH7, Mem. Soc. g-eol. France, Paleontologie. Vol. VII. No. 17. pi. lt>. tigs. 7. S. A liiglilv compressed keeled form with costa' having tubercles on the umbilical shoulders, as in some species of Hemitissotia. The sutures are described in the notice of the genus. Locality: North Africa. Age: Senonian. TISSOTIID^ Hyatt. This family name is here much narrowed in its application as compared with what it was in n\y chapter on Cephalopoda in Zittel's Textbook. It is now considered applicable to a series of genera that includes only Tissotia and its immediate allies, excluding Pidchellia, Psilotissotla and Lopholohites. The genera can be described as having keeled forms, with channels only in primitive genera. The keels have a crenulated or nodose stage in a number of pi'imitive genera, but are continuous in the flattened forms. Costfe are present in tlie globose pi-imitive forms and are usuall}- tuberculated, and when they di.sa])))ear the nodes are apt to persist. The venters lose their keels and become rounded or flattened in old ag-e. One genus has a hollow keel {Paratissotki) and others may have hollow keels. So far, however, the only fact in favor of this is the presence of prominent keels on the shells that have no corresponding keel elevations on the casts. The sutures are 42 PSEUDOCERATITES OF THE CRETACEOUS. characteristic, having' simply digitated or phyHiforin, often entire or bitid saddles and narrow, often club-shaped, lobes digitated at their tops. The first lateral saddles are usually bifid, but in some forms thev become trihd. In these cases the additional saddles are added on the ventral side through the division of the outer arm of the first lateral saddle. The group as here defined is confined to the Lower Senonian in Eurojje, and the South American representatives are probably of about the same age. TISSOTIA Douville'. The definitions heretofore given of this genus have been based upon the sutures whicli, according to the views here advanced, can not be accepted when not correlatable with external characters. The type of this genus, T. tissofi, so far as can be seen from the side view given by Bayle and the front view bv Douville', is luiique in having a considerably inflated form like some S2)ecies of Suhfissotia, but with keel and ventral channels bordered bv continuous ridges, and in the extreme gerontic substage a truncated venter without either keel or channels. This certainly justifies the opinion of Grossouvre that this species is closely related to Pseudotissotia rjaUieiniei. According to the views here advocated, this genus is a direct derivative of gaUiennei of the Turouian, as has been previously suggested by Peron. TissoTiA TissoTi (Bayle). Buchiceras tissoti Bayle, 1878, Expl. de la Carte geol. France, Vol. IV, pi. 40, tig. 1. Tlssotia tissoti'DonyiWQ, 1891, Bull. Soc. geol. France, 3d ser.. Vol. XIX, p. 501, tig. 1. Tissotia f!f'Ounger stages, so far as known, beginning with the neanic stage, have, as a rule, very globose forms with continuous keels, the sides are costated and terminate outwardly, with tuliercles that form raised but discontinuous ridges on either side of the keel. The venter is much broader tlnui tlie area included within these lines of nodes, except in the gerontic stage, when it narrows down to the same limits as are common in Metatissofia. The keel disappears in the gerontic stage and the lateral costae and the nodes also in some species, according to Peron's ligures, leaving the venter more or less rounded. Tvpe is Si(bfissofia inflata (Peron). SuBTISSOTI.\ INFLATA (Perou). Tissotia tissofi var. infiata Pei-on. 18!>7. JVIeui. Soc. geol. France, Paleontologie, Vol. VII. No. 17, pi. 12, %. t;. The figures of this form, given b}- Peron, show an excessively stout shell, increasing rapidly in transverse diameters by growth, with an obtusely subacute venter, prominent keel, and slight cliannels on either side, bordered by ridges. Peron's figure at diameter of 68.5 mm. is 51 mm., while the figure of intermedia^ which is 92 mm. in diameter, is 53 mm., only 3 mm. wider than the much smaller and yoiauger specimen of inflata. Such differences of pro])ortion do not occur in the same species of Anmionites. Locality: North Africa. Age: Base of Senonian. SUHTISSOTIA INTERMEDIA (PerOu). Tissotia tis.s3. This is based on a specimen from Tunis, of a diameter of 107 mm. It is figured by Peron as having an entire keel throughout, although the rounded tubercles on either side of the ventro-lateral angles have almost disappeared at a stage when in his cwaldi var, africana they would have become elongated and very coarse and the keel have been resolved into elongated tubercles. The venter is also entirely distinct in this species, in its sharper outline and more prominent keel. These features are also associated with jieculiar sutures. The sutures of Tissotia africana have a long, well-defined ventral lobe, the sides of the first laterals being abrupt, whereas in this fossil there is a very .short, ill-defined ventral lobe, with the sides of first lateral saddles denticulated and sloping. The first lateral saddles are deeply divided in T. africana, while in this the division is not so well marked. Tlie resemblances in form and sutures between this and T. Icpviffata show that they are closely related. Locality: North Africa. Age : Base of Senonian. SuBTissoTiA AFRICANA (Peron). Tmotia ewaldl var. nfrivniia Peron. is'.t7. Mt'ni. Soe. gvol. France, Paleontologie, Vol. VII. No. 17, pi. 11. tigs. 1-H. At a diameter of 54 mm. tlie young figured by Peron is a very gibbous form, in which the broadest diameter of the last volution measures about 39 mm. The keel is continuous and prominent even on this cast, and there is a line of prominent tubercles on either side along the ventro-lateral angles. In the aged specimen, figured at diameter of 108 mm., these have become elongated, find the sides being less gibbous the venter is flatter, and on this volution the keel begins to disappear, becoming resolved into elongated nodes. There are no cost* figured on these casts. Peron con- siders tills identical with Tissotia rohini, as figured by Grossouvre, but rohii/i TISSOTllD.^. 45 is a costated aompressed species witli a continuous keel, even in extreme age, after the d isappearance of the hnes of tubercles, according to Grossouvre's figure. His eiraldi is similarly figured as a compressed shell, but not in extreme of age apparently. This species is evidently distinct from T.ewaldi figured b}- Peron in his MoUusques Crc^taces de la Tunisie, which attains a large size, and at an advanced age still has an entire keel and rounded tubercles. The resemblance of the young of this species to the more mature stages of Suhtissotia inflata and intermedia is apparent, if Grossouvre is coiTect in his assignment of the smaller casts figured to this species. Localiti/: North Africa. AJ>>j>hi/ll(i Redt('nl)acher, 1873, Al)hancll. K.-k. o-col. Reichsanstalt. \ci\. V, pi. 23. TisHotia hajylopliijllii (pars) Grossouvre, 1893. Ammonites Craie superieurc. pi. 4. fig. 5 (not figs. 3. -4). This form is ooiupressed, lint has heavy fold-like costfe and very stout nodes on the umbilical shoulder and ventro-lateral angles, the venter being- similar to that oiM.fourneli, but with a line of nodes instead of a con- tinuous keel. The French fossil quoted above may possibly be the same, but it has quite a distinct aspect, and the supposition of Grossouvre that the sutures will prove to be similar when those of the Austrian specimen are better known, is not sustained by the collateral evidence. Grossouvre's figs. 3 and 4 of the supposed neanic stage of his haplophylla are certainly quite distinct, having an entire keel and aspect allied closely to Mefafissofia fourncli and rohini and here treated as distinct under the name of 3feta. nodosa. Locality: Austria. Age: Senonian. Metatissotia ewaldi (von Biich). Ainntonites eimldi \on Bucli, Abhandl. K. Akad. Wiss. zu Berlin, 1848, pi. 6, figs. •>. 7. Thsotia eioaldi (pars) Grossouvre, 1893, Ammonites Craie superieure. pi. -t, fig. 6 (not pi. 9. fig. 5). This species is very similar to Meta. rohini, but, so far as known by the figures of Grossouvre and others, these two species appear to be distinct in their sutures. Both species have the first lateral saddles deeply divided and the outer arras of these are shorter than the inner ones, but the outlines of these outer arms in this species are rounded, phylliform, undivided, and straiglit or jiarallel with the keel. In robini these outer arms are inclined toward the keel and the outlines are subdivided by marginal lobes in mature specimens. Locality : France. Aye: Senonian. TISSOTIID.E. 49 Mktatissotia auressensis (Peron). Timotia auressenms Peron, 1897, Mem. Soc. geol. France, Paleontologie, Vol. VII, No. 17. pi. 13. figs. 4. 5. This is a cast of what is apparently an old shell. The form is not unlike that of Paratissotia grossouvrei, with a similar large umbilicus, and it might be considered as perhaps the gerontic stage of this species, but the sutures are so distinct that this supposition is not tenable. These have extraordinarily large and long phylliform saddles, and the first lateral saddle has a conspicuously ti'ifid base. Locality: North Africa. Age: Senonian. Metatissotia sLizEwifzi (Fallot). Buchiceras sUzewiczi Fallot, 1885, Ann. sci. geol.. Vol. XVIII, p. 240, pi. 2, tig. 2. Tissotia sUzewiczi Grossonvre, 1893, Ammonites Craie superieure, p. Ifi. fig. 2.5; pi. 7. fig. 2. This species, if correctly given by Grossonvre, has a young form which at a diameter of 41 mm. has a truncated venter, continuous keel, a line of small tubercles along each ventro-lateral angle beginning on the last volution at about this size, and also a line of nodes on the umbilical shoulders. The form at this stage is like that of Tissotia c£ fourneli Peron. The sutures are also similar in having trifid first lateral saddles and othei- saddles and lobes long and large. The three marginal saddles and loljes are much more completely developed, longer, and the first lateral saddles broader in consequence of this difterentiation of the outlines. The nodes on both lines are much larger in the large shell figured and the keel persists. The lunbilicus is also of good size, as in the species of Peron referred to above. Peron considers all of these forms to have occurred in the Senonian, and his evidence is very strong on this point. Locality: France. Age: Coniacian, base of Senonian. MON XLIV— 03 1 50 PSEUDOCERATITES OF THE CRETACEOUS. PARATISSOTIA n. gen. Hyatt. Highly compressed smootli fonn.s like the type of this genus, P. regularis eindficheuri, omit the characteristic nodose stages and more or less obtuse or flattened keeled venters of Metatissrdla or else pass through them at an early stage, becoming later highly acute and smooth or at least without prominent nodes in their mature stages. In the two species examined thev never have channeled venters at any stage. The discovery of a hollow keel in the later stages of P. regularis would have caused me to separate that species from the other species referred to this group had their development been different and the structure of their keels also known. Paratissotia gross(1uvrei (Peron). Tmotia ffrosscnivrei Peron. 1S1>T, Mem. Soe. geol. France, Paleontologie, Vol. VII, No. 17, pi. lt>. tios. 1. 2. This is similar in a.spect to P.ficlieurl, but is less involute, the umbilicus beiiio' much larg-er and the sutures distinct. The first lateral saddles have denticulated outlines instead of the smooth, phylliform arms of P. ficheuri The voung have not been examined, but the adult appears to belong to this genus. Locality: North Africa. Age: Lower Senonian. Paratissotia ? THOMASi (Perou). Tissotia thomasl Peron, 1897, Mem. Soc. geol. France, Paleontologie, Vol. VII, No. 17, pi. 13, fig. 3 (not pi. 16. tig.s. 5. 6). The type of this form is a compressed shell with very involute whorls and the zone around the umbilicus depressed and flattened. The venter, at least in advanced age, has a simple, not very jjrominent keel, unaccompanied by tubercles of any kind and sides almost smooth. The form is not sufficiently well known to be placed here without a query after the generic name. Locality: North Africa. Aye: Base of Senonian. TISSOTIID.E. 51 Paratissotia FicHEURi (Cxrossouvre). Tif:sotiaiir}u'uri. Grossouvre. 1S93, Ammonite* Craie superieiire, p. 35. fig. 17. Tlssotia fchcurl Peron, ISHT, Mem. Sue. geol. Fmnce, Paleontologie, Vol. VII, No. 17, pi. 12, figs. 1, 2; pi. IS. fig. 2. Bxichicm'os eioaldl (pars) Peron, 1S90. Moll. Cret. de la Tunisie. pi. 1.5, figs. 3-6. BacUcerm fournell (pars) Bayle, 1S7S, Expl. de la Carte geol. France, Vol. IV, pL 40, figs. 2 and 4 (not fig. 3). This is a very mucli compressed shell, with no chiinuels on either side and no tubercles on the costre, which are simple and very slightly developed. The keel is prominent and acute, and the timbilicus is very small. The costre are shown by Peron in the side views of a young specimen having a diameter of 55 mm. and in a very old shell with diameter exceeding 115 mm. In both the costa> are linear and straight, with onlv the outer half developed. A description of this last specimen, which is evidently very old, would have been of much interest, but it is not o-iven. The very broad, low denticulated saddle occupying the extremity of the ventral lol)e and the deeply divided denticulated first lateral saddles of this species, of which the outer one is bifid and the inner has a broad, phylliform base, are very peculiar, as are also the costpe. The very globose fossil figured on pi. 15, fig. 8, by Peron in his Mollusques Cretaces de la Tunisie as part of his BucMceras ewaldi is undoubtedly a distinct species, but the information given is too limited to enable one to refer it to any known sj^ecies. The reference of part of B. fourneli Bayle to this species is given on the authority of Grossouvre. Bayle's figures are handsome, but not very instructive. Locality: North Africa. Afje: Base of Senonian. Paratissotia serrata (Hyatt). PI. II, figs. 7-11. BucMceras serratum (pars) Hyatt, 1875, Proc. Boston Soc. Mat. Hist., Vol. XVII, p. 370. This is a fragmentary cast of more than one-half of an entire coil, without livinfj- chamber. The diameter without the shell is 37 mm. The outer volution measures 20 ram. at larger end, the umbilicus 4 mm., and opposite 52 PSELTDOCERATITES OF THE CRETACEOUS. side of outer volution from line of involution to venter is 17 mm. The shell reduces the diameter of the umbilicus to 3 mm. The cast of the outer volution is perfect only on one side. This is planoconvex and covered with regularly arranged costae, of which there are eight to half of a volution on the inner part of the whorl. The costae broaden and flatten outwardly, becoming sigmoidal in curvature and then bifurcate, the branches bending well forward and rising into elongated swellings on the cast. These are about 3 mm. from the outer edge of the keel, and tliere are very slight obsolescent ridges beyond them, which, however, do not cross the smooth bands on either side of the keel. The venter on the first part of the outer volution, the third quarter, is subacute, but on the last quarter it is beginning to be rounded, the keel having disappeared. This shows that the shell was in the gerontic stage, and the approximation of the last two sutures also indicates the same stage. There is also the trace of a line, probably a line of involution, impressed upon this part of the outer volution, showing that the living chamber must have decreased very rapidly in the amount of involution, since it did not cover quite half of the sides on the third quarter and part of the fourth quarter of the now exposed volution. The length of the absent living chamber could not be determined, but that it was much rounded and depressed on the venter and in an extreme stage of gerontic degeneration is highh" probable. Tiie sutures are more like those of Faiatissotia fourneli, as figured by Grossouvre in his Ammonites de la Craie supe'rieure. The ventral lobe is, however, very short, broad, and opens widely, with two small, short, entire arms. The siphonal saddle is broad, prominent, and entire, with a hardly perceptible median marginal lobe or depression, which seems inclined to disappear in the gerontic .stage. The first lateral saddle is large, as in other species of this group. On the third quarter of the exposed volution it is plainly only one bifid saddle, but on the fourth quarter the dividing marginal is deeper, and there appear to be two dis- tinct saddles, as in P. djelfensis. The outer arm of the saddle shows a hardly jierceptible median marginal, as in P. fourneli. Thei-e are five other lateral saddles, all entire, and, like the first lateral, very short and extremely broad like those of P. ficheuri, as figured by GrossouATe. The first lateral lobe is broad at the end and denticulated exactly as in Tissotia tissoti and Metafissotia eivaldi as figured by Douville, but it is very short and broad. The second laterals are smaller and also denticulated. TTSSOTIID.E. 53 The remaining lateral lobes are like those of the same species, but very much narrower, and the second to the fifth hardly more than mere indentations. The dorsal sntnres were seen only from above. The antisiphonal lobe was obviously ver}- narrow at the base, but its length could not be determined. There are seven pairs of entire zygous dorsal lobes and saddles, the latter nuich narrower than the external laterals. The first and second lateral saddles are connected across the septum by broad ridges, so that the septum observed was convex externally and internally along the mesal plane, but concave along the center. The saddles on the dorsum and the corresponding extei'ual saddles were connected only by very slight ridges, and the intermediate surface of the septum was convex. The figures of sections show the liroad globose, keelless form of the uepionic stages and perhaps of the earliest of the neanic stages. The siphuncle is certainly very small ;nid the keel is solid when it first appears, as shown in figure. The disa|)pearance of the siphuncle left me in doubt with reference to its structure in later stages. LocaVdjj: Cachiyacu, west side of Huallagua River, Peru. Age: Upper Cretaceous, probably Senonian. Paratissotia regularis n. sp. Hyatt. PI. III., tio-s. 1-t!. Buchiceras servatiun Hyatt (par.s), l.s7,5, Proc. Boston See. Nat. Hist., Vol. XVII, p. 870. This species has a broad volution with a rounded venter until tlie shell reaches a diameter of G nnn. A broad, low keel next makes its appearance and the next volution becomes helmet-shaped in section. There is cer- tainly one line of nodes on the umbilical shoulders at this time, and the umbilical zone is broad and at an angle of about 45° with the line of involution. This helmet-shaped section, with more or less gibbous sides, is retained through life, but becomes more compressed; the keel becomes subacute and prominent, and slight concave zones apjjear on either side of it. An outer line of tubercles appears on the edges of the elevated venter, and both lines increase steadily in size. The umbilical zone becomes rounded and is in the first ephebic substage at right angles to the plane of coiling. The two lines of tubercles are connected in the ephebic stage. 54 PSEUDOCEKATITES OF THE CRETACEOUS. aud possibly earlier, by faint costse, wliicli bend forward ontu the venter but do not cross the keel. These were observed on the ea.«t alone, no shell being present on the parts observed. The young were seen only in section, and the nepionic stage was comjjletely destroyed, so that the earliest part actually seen was proliably in the ananeanic stage. The sutures were developed on the ephebic volution, and there is no close similarity to those of any described species of this genus. They have a siphonal saddle, and first lateral saddles on both sides more like those of Hemitissotia djelfensis Peron than any other. The inner arm of this saddle is, however, bifurcated instead of being entire, and the outer arm is trifurcate instead of l^eing bifurcate as in that species. The siphonal saddle has an inner rounded marginal like that so common in SpheitodiscKS. There are five pairs of entire saddles on the sides, inside of the first pair. The lobes more than the saddles are like those of Peron's species, liut tliev are more symmetrical in outline and longer and naiTOwer in proportion. It is interesting, however, to note that its nearest affine in form is also an African species, Paratissotia ffrossouvrei of Peron. This is close enough in external aspect to have been considered identical but for the sutures, which are quite difterent. Peron's form also appears to have had a solid keel. The surfaces of the septa and the dorsal sutures difi'er from those of Paratissotia serrafa in that there are only four broad zygous saddles and lolies on the dorsum, and the saddles are directly connected with the external saddles by broad ridges that flex the floor of the se])ta correspond- ingly. The internal wings of the septa are also straight. The antisiphonal lobe, so far as seen, seems to be much broader than in that species. The voung nmst have been similar to that of Paratissotia serrafa in form, and keelless until the neanic stage was reached. The keel was at fii"st solid and then became hollow. Locality: Cachiyacu, Peru. Age: Upper Cretaceous, probably Senonian. Incertae sedis. TissoTiA cossoNi Peron. Tissotia cnssovi Peron, 1890, Moll. Cret. de la Tuuisie, pi. 16, tig's. 1, 2. This is a large fossil, 248 mm. in diameter, with acute venter exactly similar to Sphenodiscus in aspect and evidently extremely aged, as shown b}' TISSOTIID.E. 55 the ovei-lappiug of the last sutures. These have h.\\% liroad, entire saddles aud broad lobes, very different from any observed in that genus. The youno-er sutures resemble those of Tissofla more nearly than those of Sphenodiscus, the saddles being phylliforni and entire. The ventral lobes as figured are quite different from those of any described species, so far as I know. How )nuch of these peculiarities can be attributed to the metamor- phoses of age remains unknown, but these ventral lobes have apparently no siphonal saddles except a minute point that seems to be becoming obsolete. Unluckily this important point is not mentioned in the description. Locality: Bir Oum-el-Djof Age: Campanian. TissoTiA GLOBOSA u. sp. Hyatt. Thsotia thammi Peron (pars), 1S9(», Moll. Cret. cU- la Tunisie. pi. Ifi, figs. 5. 6 (not pi. 13, fig. 3). This fossil, figured on pi. 16 Ijy Peron, has a globose form with distinct proportions from the type of tJiomasi, and the umbilical shoulders are quite prominent. The sutures also are distinct according to the figure given. The aspect indicates affinity with Metatissotia rather than Paratissotia. Locality: North Africa. Age: Senonian. HETER0TI8S0TIA Peron. If the type of this genus had been abraded so as to round off the venter, its sutures wovild have placed it near Tissotia, if not in the same genus. Nevertheless the flattened venter with keel, and the bifurcated, fold-like costfe ending in slight tubercles on the edges of the smooth ventral zone and gathered into a few large nodes on the prominent umbilical shoulders are similar to those of several species usually included in Pulchellia. The affinities of this fossil appear to be indeterminable without some knowledge of the voung. Heterotissotia neoceratites Peron. Heterotis8otia neoceratites Peron, ISttT, Mem. Soc. geol. France, Paleontologie, Vol. VII, No. 17, pi. 10, figs. 9. 10. Sufficiently described above, except that it is an involute compressed form with flat lateral zones and small but not veiy small umbilicus. The 56 PSEUDOCERATITES OF THE CRETACEOUS. involution covers up entirely the sides of the last volution, but it is obvious that until a late stage preceding this, it is not so complete, leaving a large and more open umbilicus in the young. Locality: North Africa. Age: Senonian. SPHENODISCIDiE. This is a provisional group to include genera having three principal lateral lobes and saddles and numerous auxiliary lobes and saddles which are more distinctly phvlliform than is usual in the Tissotidse, also having keeled venters. There are three genera: Indoceras, Libycoceras, and Sphenodisms. The development of the first and second genera, and whether they have a solid keel, is not known, but the third has an acute venter from an early stage and has also a solid keel. Nearly all specimens having hollow keels exhibit a truncated aspect on the venter of their internal casts which is not shown in any figures of Indoceras and Libycoceras INDOCERAS Noetling. hidoceras has been placed in the Sphenodiscidfe near to Libycoceras because of the external characteristics of the later stages of the type species described below, and because the sutures in both the species described by Noetling have resemblances to those of Sphenodiscus. As in many other published forms, there is no description of the earlier stages, and the dorsal sutures, whicli would also greatly assist in drawing correct inferences, are still unknown. The essential distinction between this and Sphenodiscus lies wholly in the fact that the saddles are entire in this genus instead of being- divided or denticulated as in the former. Indoceras baluchistanense Noetling. Indoceras haluehistanejisis Noetling, 1897. Pal. Indica, Series XVI, Vol. 1, pt. 3, pi. 21, %. 2; pi. 22. tigs. 1-3. According to Noetling's figures and descriptions, this interesting species at a diameter of about 40 mm. has elongated forward-bent ridges on the outer part of the volution that are obviously the remnants of sigmoidal costse. The venter at this stage is somewhat obtuse, but tending toward being subacute, with a keel bordered by smooth zones and obscure ridges SPHENOmSC'ID.E. 57 on either side In later stages the venter becomes planoconvex, tlie keel and lateral ridges having disappeared. These characteristics are very similar to those of Sjihenodiscus pleurisepta. The sntures have entire phylli- form saddles that resemble those of Sphenodiscus more than those of Tissotidfe. The first lateral saddles are described by Noetling as being bifid in this species, and as becoming split up into separate saddles during development. There appear to be three principal lateral saddles in the fullgrown. Locality: Mazar Drik. Age: UpjDer Senonian. Indoceras aoutodorsatum (Noetling). Sphenodiscus acutodorsatuK Noetling, 1897, Piil. Inclica, Series XVI, Vol. I. pt. 3. pi. 21. iig. 3. This shell has the usual acute volutions of Sphenodiscus, but the sutures have the entire saddles of Indoceras. In fact the onh' distinction apj)ears to be that the first pair of saddles ai'e not yet completely separated, but appear to be branches of a first lateral. It might be said, therefore, that this species had only two principal lateral saddles, the first and second, the first being deeply bifid. If we reckon the sutures as having three entire principal lateral saddles, two of which are not yet fully separated, the species passes into Indoceras. LIBYCOCERAS Hyatt." This genus is founded upon a single species, which has, however, sucli a ' peculiar combination of characters that it can not be incorporated with other genera. Zittel recognizes the affinity of this form to Sphenodiscus and describes it as liaving three principal lateral saddles. The sutures have phylliform entii'e saddles and simply digitated lobes, and resemble those of the young of S. lenticularis after they have passed through the stage in whicli both saddles and lobes are entire. The median lateral line of tubercles and l)road costa* connecting these with an outer line of nodes along the edge of the venter and distinct keel are, however, quite different from the tubercles and eostse and solid acute venter of Sphenodiscus, which has distinct sutures, and also diff'erent from Indoceras, which has similar sutures. aJifivKoi, Libyan. 58 PSEUDOCERATITES OF THE CRETACEOUS. LlBYCOCERAS ISMAELE (Zittel). Sp/ie)iodiscim istnaeltK Zittel. Haiulb. der P;il;vontolot>-if. Vol. II. p. 4.51. fior. fi.Sl. Lihycocerns ismaeli Hyatt, 1900, Zittel's Text-hook of Palaeontolofjy. Vol. I. p. .5><.''. According- to Zittel this has three principal lobes and saddles. Localitij : Libyan Desert. Age: Upper Senonian. SPHEXODISCUS Meek. This genus is apparently a close ally of Enffonoceras, judging Ijy it> sutures and external characters, but the development shows it to be verv distinct. In two species, pleurisepta and lentlcularis, the young were examined, and in these there were no indications of a stage having a flat or concave venter. In the nepionic stage the species is rounded on the venter which in the neanic changes directly to a form with an acute venter and flattened side like that of the adult. There are three principal lateral saddles derived from the division of the primitive first lateral saddle. The earlie.st stage described in S. Jentlcularis exhibits sutures like those of the adult of Keolobites, but the}' are also very similar to those of some species of Engonoceras having longer, narrower, and more phvUiform saddles than usual, like Engonoceras subjection. There is, however, in Engonoceras and in Neolohites also a very distinct persistent first lateral. These peculiar- ities in development of the sutures, as well as the acute venter, heighten the resemblances to the shell figured by Zittel as S. ismaeUs. This is genericallv distinct and here described as Lihycoceras, but Sphenodiscus might be a modified form of the same series in which the keel had become incorporated with the venter and with more comple.K sutures, whereas its development does not indicate descent from an^" of the genera having flat and tuberculated venters. The external characters of this g'enus are often so uniform that the sutures as a rule are the only means of distinguishing the sj)ecies. The exceptions to tliis rule are to be found in the American forms l<'ui't>^<'l>tii Conrad. 1S57. U. S. and Mex. Bound. Surv., Vol. I. Pt. II, p. 159, pi. 15, tigs. 1. a, b, c. Ammonites pedemalis Binckhorst, 1873, Mon. Gast. et Ceph. du Limbourg. p. 'IX, PI. V a', tig. 1 (no others). Sphenodiscus pleurisfptii Bohm, 1898, Zeitschr. Deutsch. geol. (resell. Vol. L, pi. 7. Conrad's original specimens, preserved in the United States National Musenin, show how erroneous and misleading- are his descriptions and tioures. The orig-inal of his fiscure has two distinct rows of lateral tubercles. Another specimen, 117 mm. in diameter, is the one cited as collected by Schott, "Yellow Stone." This has the same characteristics, but is in the gerontic stage, and the outer row of tubercles disappears on the last quarter of the outer volution. Tlie condition of the specimen, however, made this somewhat doubtful. A number of fine specimens were collected by Stanton and Vaughan near Eagle Pass, Tex. All of these have two rows df nodes on the sides, and one is a noble specimen 182 mm. in diameter (PI. IV, fig. 1-2). What appears to be the abraded edge of the aperture is present on one side, and the living chamber is somewhat over one-half of a volution in length. The inner row tif nudes is present, but the outer row is replaced on the last volution in the o-eroutic staoe \>\ broad arcuate folds. These are visible throughout the volution on the side opposite to the one figured. The venter broadens and becomes less acute on the third quarter of the ov;ter volution and is rounded on the last quarter. It is obvious from this that the specimens described below were in some cases dwarfs, the range being considerable. The interesting fact in this large specimen is that the lobes and saddles vary but slightly from those of smaller fossils. The three principal saddles and the lobes are longer; there may be one or two saddles more, making the total number fourteen, concealed under the shell of the umbilical zone; and the marginals are more numerous, but otherwise the sutures are just about the same as at younger stages. There are only five divided saddles, the first to the fifth, as in younger stages, and the remainder are entire. Another fact is that the amount of involution decreases so slightlv, even in 60 PSEUDOCERATITES OF THE CRETACEOUS. this large specimen, that it is hardly perceptible. There is, however, a broader umbilical zone in the paragerontic substage and a decided umbilical shoulder. A small cast of this species, No. 19145b, U. S. National Museum (PI. Ill, fig. 14), only 59 mm. in diameter, shows the ephebic stage. The diameter of last volution from line of involution to venter on cast is 32 mm., the same diameter on opposite part of volution is 22 mm., the umbilicus being 5 mm. without the shell. The fragments of the shell are not specially thick except on the crest of the venter, where it forms a solid keel, and in the umbilicus, where it is over a millimeter in thickness. This cast is somewhat compressed, but judging from an accompanying older specimen it is a medium stout volution with, however, a ver}' acute venter. Tliere are two lines of distinct, transversely elongated, radiating nodes, about 8 mm. apart, the outer line occupying the centran surface, about 7 mm. from the venter. The inner line gradually increases its distance from the umbilical shoulder, but on the first part of the outer volution begins to be farther removed from the dorsum than the (inter row is from the venter. The venter is blunted on the last part of the exposed volution and the parephebic substage had ]n-obably already begun in this specimen. The ventral saddle is that of Sphenodiscus, with similar marginal saddles at the inner corners, but the aspect of the lobes and saddles is like those of older specimens, except tliat they are shorter and the sutures do not overlap anywhere, and do not even apjjroach one another until near the umbilical shoulders. The lobes all have flaring tops and the saddles phylliform and rather broad bases, flattening out, however, as usual near the uml)ilical shoulders. Nevertheless, on the umbilical zone they are again slender and phylliform. The first lateral saddles are trifid, narrow at the openings, with a few phylliform saddles; the second and third are bifid a trifle longer, but of nearly the same form; the third beconu's trifid on the oldest part of this volution; the fourth is trifid and then becomes quadrifid. These form a bent outline, each being a little longer than its neighbor, beginning with the first lateral. The fifth is bifid and from thence to the umbilicus there is the usual row of entire saddles gradually shortening up and sliowing more and more primitive forms; but they become narrower again tm the uml>ilical zone. SPHEN0D1SCID.E. 61 The branches of the ventral lobe are trifid and spreading as usual, but small, of course, in such a suture; the first laterals are shorter and broader and together with the longer second and thii'd laterals form the usual arch. The fourth lateral is about half the length of the third and from this to the umbilicus there is the usual diminishing row. The type is bifid except the first and fourth laterals; these were uncertain. All are divided except, perhaps, the last and umbilical lobes; these were not seen. There are twelve saddles and twelve lobes visible, and there may be a saddle on the line of involution on the left side; the sutures of the right side were not seen. The older specimen of this species (PI. Ill, fig. 13) is a cast from same locality and is very instructive. It is 90 nun. in diameter and the form is better preserved, not having been injured by pressure. The oldest part is 47 nun. in diameter, the umbilicus without the shell is about 8 mm., and the volution opposite is Sf) mm. measuring from line of involution to venter. The greatest transverse diameter is carried farther out than the centran surface at this age and is 21 mm. between the tubercles, the greatest diameter opposite between tubercles and about centran of the lateral zones is 16 mm. No shell is present in anv of these measurements. The shell is excessively thick on the umbilical zones and is nearly a millimeter thick on the sides in the parephebic .substage; it is considerably thicker on the venter, where it forms a solid keel. There are two lines of tubercles as in the smaller specimen, the age of the first part of this volu- tion being the same as the age of the last part of exposed volution in the younger specimen, but the nodes are rounder or hardly perceptibly elon- gated. The iimer line of nodes persists and retains its distance from the umljilicus, but the nodes are slightly nearer to the venter on tlie last })art because of the gerontic decrease in the rate of growth of the dorsoventral diameter. The outer tubercles gradually decrease and disappear, but the fold-like short costae between the tubercles persist. These costse may have a bifurcated aspect when slightly better developed than in these specimens. The outer part of the whorl is decidedly convex, while the surface between the inner line and the umbilical shoulder is decidedly concave and the umbilical zone narrow and abrupt. The earliest part of this volution has the venter bluntly acute, show- ing it to be in the parephebic substage, while on the second quarter the rounding of the venter and loss of tubercles shows anagerontic substage. 62, PSEUDOCERATITES OF THE CRETACEOUS. Ou the tliird quarter folds take the place of tubercles of outer row, and on the fourth quarter the venter becomes gradually rounded. Thi.s .shifts the greatest transverse diameter from the central parts of the sides to nearer the venter. There is also a very slight decrease in the amount of involution internally. The living- chamber is only in part preserved. The younger sutures are like those of the same age in the smaller specimen, but are a tritle more complex in outline and the ventral lobe seemed to l)e shorter. This last, however, could not be made out clearly anywhere. The general chai-acter of the sutures is the same as in the younger specimen, so far as all of the remaining lobes and saddles are concerned, and there are five divided saddles. The first and second lateral saddles are probably bifid, in the young becoming trifid later and perhaps bifid again in extreme age." The third is trifid, becoming quadrifid later. The fourth is trifid throughout. The i-emainder are same as in younger specimen. Lobes appear to be about the same as in that specimen. The last two sutures are so close together that they overlap more or less throughout, and the third suture approaches nearer to the second than in younger parts of this volution. This specimen had, therefore, in all its characters jjrobably completed its cycle of development and was in the paragerontic sitbstage. There are constantly five divided saddles on l)otli sides of specimens of this species so far as seen hj me. A perfect cast (PI. Ill, figs. 7-12), labeled Rio Pecos,'' in collection of Columbia University, is 60 mm. in diameter. The outer volution measures 32 mm., transverse diameter is 13 nun., the umbilicus 3.5 mm., the opposite 24.5 mm., and the transverse diameter between tubercles of inner row 9 mm. The outer volution has already begun to show a blunted or rounded venter, and tlie two rows of elongated nodes are more distinct than in other specimens described. These also begin to become rounded on the last part of the outer volution. This is as much altered in the form of the volution (i. e., venter is as blunt) at this size as a second specimen from same locality (PI. Ill, fig. 1 (suture), and PL V, fig. 3) at diameter of 86 mm "The condition of the sutures of the paragerontic stage made this observation somewhat doubtful, because when slightly worn away the saddles lose their secondary divisions and become bifid, the central marginal lobe being always more persistent on account of its greater penetration into the interior than the more recently acijuired marginal lobes on either side of it. 6 See Mr. Stanton's note, p. 6.5. SPHENODItiCID^E. 63 The first specimen is the only one with perfect young that I have seen, and is, therefore, a very instructive example (PI. Ill, hg's. 9-12). In ananepionic stage the innermost volution next to the large protoconch is rounded and followed by a volution still in the nepionic stage. This acquires an elevated venter and becomes more compressed and helmet shaped, but has nowhere a flattened or concave venter. The sutures were simpler than those of later age. The sutures on both sides had five divided saddles. The first lateral saddles were bifid on both sides, the second jiist besrinnino- to be ciuadrifid, the third and fourth symmetricallv trifid, and the fifth tinly bifid on the right: whereas on the left side the second to the fifth, like the first, were all bifid. The volutions in section were similar in outline to the adult, having the same highly involute and almost pear- shaped section and acute venters. Neither of these specimens showed the living chamber. One specimen (Loc. 582, U. S. Geol. Survey, PI. \, figs. 1, 2), when comjiared with more typical forms, shows, in what is probably the mete- pliebic substage, the outer fold-like costfe as in the gerontic stage of others. The diameter of the cast, without the shell, is about lis mm., partly esti- mated. The last of tlie outer volution measures 60.5 mm., the umbilicus. 8 mm., and the opposite volution from line of involution to venter measures about 49.5 mm. The acuteness of the venter decreases on last part of this volution, but does not become blunted and rounded as it does at the corresponding- size in the typical form. The sutures of the last five septa show gradual approximation, and in the closer approach of the last two there are indications that the specimen was beginning its gerontic stage. The living chamber was broken away, but the marks of the umbilical parts showed that this had extended at least one-fourth of a volution farther on the sides. The inner line of tubercles wa^ becoming wider apart, and together with the venter and sutures, also indicated that the gerontic stage was begun or was about to begin, and had been perhaps nearly completed in the now absent living chamber. The sutures, it will be understood, always represent a later stage than the parts of the shell on the inner surface of which they are found. The sutures have short phylliform saddles and broad lobes, and ai'e well separated from each other and approximate only near the umbilical shoulders. They were 64 PSEUDOCERATITES OF THE CRETACEOUS. more perfect on the side opposite to the one figured. The first lateral sad- dles are trifid, the second, third, fourth, and fifth are bifid and phylliform; the remainder are similar to those of the inner columns of others of this species, but are pei'haps somewhat simpler in outlines. The exact number was not ascertained. On a frag-ment of what appeared to be the same species from the same locality, tliere were thirteen saddles at a diameter of 60 mm. from line of involution to venter. This was a cast, and slightly abraded on the venter. The ventral saddles were much worn and the first lateral saddles were entire, except for a faint median marginal in two sutures. The remaining lobes and saddles exactly agreed with those of the ephebic stage of the first specimen described, except in being a trifle longer. There were five divided saddles, as in other specimens. One of the figures of Amin. pedernalis given by Binckhorst in the monograph quoted above was taken from a Texas specimen supposed to be identical with von Buch's species. The specimen was in the Museum of Stuttgart, and was said to have come from Rio Bravo del Norte, Texas, and to have been collected by Schott. This figure is identical with the larger vai'ieties of this species which retain the acute venter until a late stage of development. This same specimen was refigured by Bohm, as above quoted, and properly named by him. Except in being somewhat older and large, it is identical with the fossil figured on PI. Ill, fig. 15 (septum), and PI. V, fig. 3. The first lateral saddles are, however, bifid, the second trifid, the third to fifth bifid, whereas all the saddles in sutures on PI. Ill are bifid, and this holds in all the sutures on this volution in this fossil. Even in the close approximation of the sutures this is similar to Bdhm's figure and also in the way in which the inner line of nodes trend outward on the latter part of the volution. A fragment in the collection of Frederick Braun, of Brooklpi, N. Y., is labeled as from rotten limestone grit, Brooksville, Noxubee County, Miss. The diameter of side is 55 mm. The inner line of nodes still remains somewhat elongated; the outer line is superseded by broad folds. The fine surface of this cast shows that the shell had sigmoidal, and sometnnes dichotomous, costse and ridges on the outer convex half of the volution, but that it was smooth and decidedly concave on the mner half. The first lateral saddles were trifid, then four bifid and nine entire. There were ten entn-e dorsal saddles at the same age, with h^bes like those of the exposed SPHENODISCID.E. 65 sides. Unluckily the antisiphonal lobe was not ex])(ised by excavation, and therefore it was not considered necessary to draw these curves. Thi.s species is very instructive, since its external characteristics are well marked and thev show that the amount of involution, the wneral outlines of the lobes and saddles, and tlie number of divided saddles remain very con- stant, while the trifid or bitid outlines of the larger saddles are -variable. These minor details of the saddles, and of the lobes also, depend on the relative growth of marginals and ma}- vary at different stages of growth or on the opposite sides in some individuals or in different individuals. The numlxM' of sej^ta may also greatly vary, thus in Bohm's and the fossil figured on Pis. Ill and Y they are 5 mm. apait near the center; in l^raun's they are 9 mm. distant at about the same age and the saddles are much longer. Another specimen from the same collection is given on PI. VI, fig. 6, and this although closel}' associated with .S'. lobatus, and apparently at first sight the }oung of that species, has all the external characters and the sutures of pleurisepta. The fossilization is in the peculiar yellow limestone, with iron incrustations of the specimens of lobatus from the same locality. It is of course possible that this specimen may be the young of lobatus, which I have never seen of as small size, but in any case it is identical with jjkurisepta of the same age, which has an acute venter on the outer volution and sutures like those of PI. Ill, fig. 15. There are five bifid saddles on the right side at the point where that side is about 30 mm. broad, aud on the left side, where 20 mm. broad, the fifth saddle shows the faintest possible beginning of a median marginal division. Locality: Near Laredo, Rio Pecos, and near Eagle Pass, Tex.; Brooks- ville, Noxubee County, Miss." Age: Eagle Pass beds, Upper Cretaceous. "The following note wa.« contributed by Mr. Stanton: "It is pretty well establij^lied that Conrad's specimens were not collected near Laredo. It is probable that they came from the neighborhood of Eagle Pass, where the species is abundant. It has been collected by Geological Survey parties from localities from IJ to 18J miles southeast of Eagle Pass. "I doubt whether the si^ecies ha.s been found on tlie Rio Pecos. There are certainly no beds that could have yielded it near the mouth of that stream." MON XLIV — U3 5 66 PSEUDOCERATITES OF THE CRETACEOUS. Sphenodiscus lobatus (Tnoniev). PI. VI, lig-s. 1, :i; PI. Vll, figs 1. 2: PI. IX, tig-s. ll-i:^. Aiiimonites lohaUi Tuomey, 1856, Proc. Acad. Nat. Sci. Philadelphia, Vol. VII, p. ItiS. The description given \i\ Tuomey of his Amm. lohatu mav of conrse apply to another species, but this is the <>nly one I liave seen to which the following words could have applied, and it comes from the same State although from another county: "Shell discoidal, smooth, thin toward the circumference;" "dorsal (ventral) lobe finely serrate." These words and his reference to the large bilobed saddles as characteristic seems to make this name applicable to this species, which is so widely diflPerent from Sphenodiscus lenticularis and its nearest aflfines that no discussion is necessary. A fine specimen (PL VI, figs. 1, 2) in Coll. Xat. Museum, labeled S. lenticularis, No. 20577, from Ripley group, Lander's mill, Tippah County, Miss., is 111 mm. in diameter. The last volution at what appears to be the aperture measures 59 mm. and the volution immediately opposite in same diameter from line of involution to venter is 46 mm. The greatest trans- verse diameter is about the middle of the lateral zone and is 21.5 mm. and for the smaller part of the volution 15.5 mm. The cast is naked except a fragment tliat shows that it did not have a very thick shell. The inner volutions are not entirely covered and the umbilicus is larger j)roportionally than in the large specimen, supposed to be the adult of the same species, from Pontotoc County, Miss. There are obscure fohl-like costae indicated outside of the greatest transverse diameter, which is nearly central; inter- nally the surface is slightly concave. There are no umbilical shoulders and no flat umbilical zone and the umbilical openings are shallow. The shell nuist have been very thick between the volutions and may have nutcli contracted the opening of the umbilicus. There were twelve lobes and thirteen saddles on the oldest part of the volution. The flat siphonal saddle has a minute saddle in the center and a couple of inflections or marg-inal lobes on either side of this and then at the ends two small round saddles. The ventral lobe is very broad and tlie two arms also broad and obscurely trilobate, each lobe being subdivided l)y a minute saddle. The first, second, and third lobes are broad at top and have an unequal number of small short branches, as if they were derived from the trifid type. The}' are all probably, however, derived from a bifid type, unless exception may be made for the branches of the ventral lobe. SPHENODISCID.E. 67 The remaining lobes have one large median saddle and an ec^iial number of small lobes as if derived from tiie bifid type There is a, series from a primitive bifid lobe, the eleventh, and only the twelfth lobe is single. On the right side the twelfth lobe is on the line of involution, whereas on the left side that line is occupied by a saddle. The lobes are very short and broad. Tlie first six saddles have broad phvlliform bases and the first five are bifid on both sides, being equally divided by a small median lohe, the sixth is transitional and entire; the remaining saddles are of the same type but so short and broad that they appear to be flattened at the base, and in fact are approximations to that type. The most remarkable fact about this east is wliat ai)pears to be tlie living chamber. The evidences of the existence of a perfect living chamber on this cast seem undeniable and there is every mark of an aperture with an entire reflected lip. And what is still more remarkable, the last four sutures on the left side are shortened as if absorbed by pressure after they had been built. The fourth has lost the three inner rows of lobes and saddles, the third has lost seven, and the eighth saddle is partly gone; the second has only f( )ur saddles left and faint traces of fifth lateral lobe and outer side of the saddle, and the basal septum is represented by hardly perceptible traces of first, second, and third lateral saddles, no ventral or imx other lobes. On the right side the pressure of the bod}' has shortened up five of the sutures. The fifth has lost all the inner entire saddles and their lobes except one-half of the last outer one, the sixth row from tlie u}nbilicus and the seventh from tlie venter. Tlie fourth has lost this remaining half and part of the next saddle, the thirilicus, this being practi- cally sealed up Ijy the growth of shell on one side, and is of course very small, where cleaned out on the other side. There are faint folds on both shell and cast. The folds occupy the sides and are not confined to the outer or inner parts of the lateral surfaces, although more j^i'ominent along the centran lateral lines. The keel is solid in the younger stages (PI. XI, figs. 5, 6) and then becomes apparently hollow. The proof of this is not al)solutely clear, but in each volution of the section there is a ]iartition of shell outside of the siphuncle. In the upper tip of the section of the volution next to the last a partition was also present, but this is apparently a section of the sejDtum itself, and what seemed to be the siphuncle is represented on the right and above this partition. If this be correct the keel is solid at this age and remains in this condition in the last volution. The siphuncle is not present in this last volution, but as in the section of the next younger volution above described the common matrix fills the interior completely and on the outer exposed edge the sutures run against the solid interior of the thick deposits of the keel. In the younger whorls the space between the parti- tion above the siphuncle and tlie keel is filled, as in the interior of the siphuncle, by dark transparent calcspar. There is, however, no black layer present above the siphuncle, as in the Jurassic forms, that have hollow keels The sutures are extraordinary. They are so excessively overlapped that there are two second lateral lobes telescoped into every third one, so that one has to disentangle the lines of three consecutive sutures in marking out this lobe. It becomes necessary, in fact, to infer outlines that can not be seen, the sutures having in some parts necessarily passed along the same lines and can not be separated by the eye. The first to third lateral saddles are broad and have numerous long tongue-sliaped marginal saddles. The fourth lateral saddle is also broad, deeply bifid, the outer arm entire, the inner bifid. About half of a volutifin earlier this saddle is much nar- rower, and is probablv still smaller at youngvr stages. The fifth is al.-i/e»/' Groiif>ouyvQ. lS!t3. Ammonites Craie superieure, p. 141. tig. 59. The suture and description given by Grossouvre of his French species and the one fig-ured by d'Orbigny as Ammonites rrqidenianns, ahhoug-h quoted as identical by him, are very difiPerent. There are distinctly three principal lateral saddles in (irossouvre's figure, but the first is large, long, and trifid instead of being narrow, long, and bifid; the second is really an enlarged branch of the first saddle and still entire, while the third is bifid and much larger than in true rcquieni, according to d'( Jrbigny's figure. This species may be one of the hollow-keeled group, a suggestion that is further supported by the aspect of the auxiliary saddles and lobes. In order to call attention to these points I have placed a question after the generic name. Locality: Near Tours, France. Age: Turonian. ACONECERAS" n. gen. Hyatt. The single species here referred to this genus has sutures more like those of Cretaceous forms of Phylloceratida than any others of this group. These are combined with a highl}' involute compressed shell having an ax-like acute venter like a species of Euhphoceras. The A-entral saddle, as figured l)v d'iJrbigny, is broad and similar to that of CoUopoceras: the first lateral and the other saddles are deeply divided and broader tliau in the Phylloceratida and certainly show approximation to those of the Coilopo- ceratida?. I have therefore referred the form to this family, and it appears to strengthen the opinion that the Coilopoceratidji? were derived from the Phylloceratida?. AcoNECERAS NisuM (d'Orbigny). PI. XII. %s. J-tj. Aiiiinonitef: )i,ism d'Orbigny. 1840. Terr. Cretace, pi. 55. This figure is copied from d'Orbigny because it gives what appears to be an important link in the evidence that the group to which it is referred is correctly referred to the Phylloceratida.'' Age: Neocomian. " Akovi;, a whetstone. ''The twc.i pages of manuscript bearing these notes on Aconeceras were out of place, lying at the ti le Chili, etc., p. 10, pi. 2, ligsi. 2-5. Retains the tuberculate stage until quite large, and in the full-grown shell, which is of great size, the last volution being 80 and 90 mm. in diameter in one specimen, there are still six lines of well-developed tubercles and the subquadrate form of the volution is but little modified This is by far the most primitive form of this group. METOICOCERATID2E Hyatt. This family is necessarily instituted for a peculiar group of species whose development does not admit them within the pale of either Heinzidse or Pulchellid», but whose later stages show that they belong in the same group with the latter. The family and generic and to some extent specific characters are necessarily mingled in the following descriptions: 116 PSEUDOCERATITES OF THE CKETACEOUS. METOICOCERAS" n. gen. Hyatt. The young, altliougli distinct from those of Heimia, enable us to connect Heinzia and its more modified allies with what I have misnamed in Zittel's Text-book the Pedioceratidfc/' here corrected to Mantelliceratidse. The tyi)e species, if the full-grown shells were the sole evidence, would necessarily fall into the same genus with Heinzia matiira on account of the resemblance of the compressed later stages. But the following description of the young shows this to be a case of raorphic equivalence based on entirely distinct modes of development. The earliest stage observed has a coronate form with large lateral tubercles. Tliis stage is of short duration and appears on what seemed to be still the nepionic stage at about 2 to 2.5 mm. in diameter. The venter at this time is liroadly rounded and without costae on the cast. Subsequently at diameter of about 3 mm. the ventral rows of tubercles begin to appear upon fine costse that pass across the venter and connect the rows of tubercles, and the costae also begin to spread inward on the sides. The termina- tions of these at 4 nun. diameter were without tubercles. The costae are partially bifurcated at the outer row of ventro-lateral nodes, but onl)' one of each pair passes across the venter. The two rows of ventral tubercles are borne upon this costation, and in front of each one is a depression or transverse furrow exactlj' like those that are so peculiar and characteristic of Cheloniceras royeriammi. Intermediate costae begin to appear a little later and at first are without tubercles and are single. In this stage there is an evident modification of a late neanic substage of Cheloniceras, which has similar costa?. but a more coronate form. These costa? subsequently form a branch of the dichotomous lateral costations or may remain single and short. Though the resemblance to Aspidoceras is apparent, the general form and aspect at this age can be accounted for as a parallelism with Psen- daspidoceras of India, which is one of the same stock, and arises as the result of the assumption of the subquadrate form after the coronate stage in related organisms. It is of course very likely that this Aspidoceran aspect may have some genetic significance, but the connections that would prove this are not as yet clearly made out. One can not accept all of the characteristics that appear in larval forms as of unquestionable genetic significance. Thev are safe guides onh- wlien carefully compared and " MiroiKO';, an emigrant. ^ See MantelliceratidiP. METOICOCERATID.E. 117 systematically liandled with due regard to the collateral evidences, deduci- ble from the later stages of development and the obvious relations of the adult and even senile stages. Thus in the present case, wliile the young would place this genus entirely outside the pale of the Heinziidfe, the later neanic and the ephebic stages and old age and sutures show them to belong near that group. The peculiar elongated erestlike tubercles, the costiie, and iinall}- the sutures are of the Pulchellian type. When these later stages are allowed their full weight, it is then seen that the development shows Metoicoceras to be the descendant of some common form from which Carstenia tuherculafa and Heinzia provinciaUs are also descended. It is also apparent that this must have been either similar to or identical with some species of the coronate genus described here as Cheloniceras. The coronate young of Metoicoceras are not reconcilable with the young of Heinzia nor any other form of this family, so far as known. The develop- ment of Heinzia ditfers in the suppression of the coronate stage and of the sextuberculate stage and the appearance of the approximated lines of tuber- cles on the venter of the Heinzian type by a tachygenic mode of develop- ment common in this group. The difficulty of reconciling the development lies in the fact that the outer rows of tubercles appear later thnn the ven- trals and are not developed, like those of Metoicoceras, from a primitive row preceding the ventrals in development. This may be a case of what Cope has called retardation of development, but if this is so, the effect is really to accelerate the appearance of the Heinzian characteristics of the venter. The sutures of the entire gi-oups of Cheloniceratidse and Mantelliceratidse are of the same type. The number of lobes and saddles is nmch more limited than in Heinziidse or Pulchelliida?, both on the dorsum and externally. The outlines also are excessively complex, with a certain ragged look due to their long, subdivided marginals, and also apt to be asymmetrical or trifid rather than bihd. There is also a noticeable absence of simple entire sad- dles and lobes in the umbilical region. Comparison of the sutures of Metoicoceras with those of Heinzia or Pulchelliu shows at once resemblances that are quite close enough to place swallovi in the same group with Heinzia, and the sutures of Metoicoceras are especially close to those of Carstenia! tuhercidata. The development, being irreconcilable with that of any form of Heinziidse or Pulchelliidse, shows that the genus can not be placed in either of these families without confusing the picture of their systematic and genetic relations, so far as now known. 118 PSEUDOCERATITES OF THE CRETACEOUS. Metoicoceras swalloyi (Shumard). PI. XI, figs. 7-24; PI. XIII, tigs. 1, 2; PI. XV. figs. 1-4. Ammonites stoallovi Shumard, 1859, Trans. St. Louis Acad. Sci.. Vol. I, p. .591. So far as I have been able to see, this species has not been previously fio-ured, but that described below as ivhitei has been the one selected as the typical form of swallovi. The following quotation from Shumard's description shows that while he had in hand perhaps both of the species here described his remarks seem to apply more decidedly to the one selected as sivallovi rather than to its less prominently nodose and more complex companion. Shumard states "dorsum [venter] flattened, transversely ribbed, nodose-bicarinate ; * * * umbili- cus deep, exhibiting about one-third of each of the inner volutions and about as wide as one-half of the width of the last volution." If he had in hand such a specimen as the one he mentions as being 6 inches in diameter, and it was a representative of tvhitei, this large umbilicus would be just about in this proportion, but it would be inapplicable to an ephebic stage as a young specimen of this species. If he had had a specimen of M. sivallovi, the large umbilicus would have been found in the neaiiic and ephebic stages in about this proportion. Shumard's other remarks apply also about equally well to either species, but the sutures, as described by him, point out quite clearly the typical form. "Dorsal saddle almost double the width of the superior lateral lobe and divided into two unequal branches by a short subcorneal auxiliary lobe; the dorsal [outer] branch having three small notches, while the inner one is rounded and has usually only a single small notch at its internal border." Such simple outhnes as these occur only in the forms here referred to as sivallovi, and one of the specimens (PI. XIII, fig. 2) came from Grayson County, Tex., the typical locality quoted by Shumard. The young figured (PI. XI, figs. 7-15) and the sutures (PI. XI, figs. 18-23) were taken from a specimen found in a piece of the matrix cracked off" from the specimen shown in fig. 16 and are quite likely the young of this species, but it is probable that at this age the diff'erences are slight between this species and whitei. Tlu-ee specimens were obtained from this piece of matrix. That to which figs. 12, 13 belonged reached an older METOICOCERATID.E. 1 1 9 stage than figs. 14, 15, and the last node near the umbiHcus on this was considerabh" hirger than the preceding nodes, indicating that this young- one belonged to this species. The breadth of side at this age was about 9 mm., the transverse diameter about 6 mm. The breadth of the side at the base of the living chamber, which was badly crushed farther on, in fig. 16 is 20 mm., while the diameter between the tubercles is 16 nnu. The young volution was quadrate in form, the sides parallel, whereas in the specimen represented by fig. 16, as may be seen in fig. 17, the lateral zones are highh- inclined and the venter much narrower than in the young. In the fossil shown on PI. XII, fig. 2, the breadth of the side at the third suture is about 33 mm., the transverse diameter between the costal being 23 nun. The outward inclination of the sides in this specimen was not so great as in the fossil represented by PI. XI, figs. 16, 17, even at the same stage, and the nodes near the umbilicus were apparently not quite so prominent. Besides the marked prominence of the nodes and their dichotomous costa?, the li^•ing chamber in the young (figs. 14, 15) is clearly nearl}^ three- fourths of a volution in length, while in the later stage it appears to be in part complete and to be one-half of a volution in length. It is obvious that this species becomes more compressed with increasing age, and has a much narrower venter and less transverse diameter in proportion to the ventro- dorsal than in the young. The protoconch has an arcuate venter (PI. XI, figs. 7-10) and rounded dorsum, with subangular bend as the outline approaches the opening of the conch. This opening, doubtless once the aperture of the protoconch, is much depressed or broad transverselv and continues to have this form throughout the ananepionic and inetanepionic substages. The elevation of the venter begins in the second volution, fig. 10, but the form remains smooth and the sutures goniatitic until about the fourth volution." Then nodes begin to appear on the ventro- lateral angles and the venter becomes broader in consequence. The venter is smooth at this substage, the first of the neanic substages. In the next substage, about one-half of a volution later, fig. 14, the costge become more prominent near the umbilici and wrinkles appear on the venter, each accompanied by a pair of tubercles. In the next substage, which was not seen, it is probable that these ventral costse become connected with the lateral ones and equal in number to them, and nodes appear on the innei- 0 This was guessed at. 120 PSEUDOCEKATITES OF THE CRETACEOUS. ends of the lateral costse and there fuse into more or less dichotonious forms. This fusion is not as complete in the fossil shown in fig. 16 as it is in the one shown in PI. XIII, fig. 2, at a later age. The sutures seem to follow about the same steps in progress of devel- opment as the external cliaracters. Fig. 11 gives an enlarged sketch of (•a?cum, which seems small in this specimen and which ojjens into a large siphuncle, whose parts could not be .studied any further than is visible in the drawing. Although every eifort was made, and this specimen was remarkably clear and transparent, nothing definite could be made out beyond the cpecum. It is certain that the dark color of the wall of this V)()dy has no posterior prolongation or prosiphonal continuation. The second septum, beginning tlie sutures of the metanepionic substage, had unquestionably a divided ventral lobe, as given in fig. 10. This was estab- lished by many repeated observations. There were, as usual, but two broad goniatitic saddles of the Tornoceran type on either side and one broad lateral lobe on each side, with a distinct saddle at the line of involu- tion. I was not able to detect any depression, such as I have prcAaously described in other forms as an embryonal umbilicus, occurring at the begin- ning of the true conch. In the paranepionic substage the suture becomes distinctly divided on the sides into two broad saddles, with a lateral lobe and a lobe at the line of involution on either side, and during this substage the dorsal suture assumes finally the aspect given in fig. 21. The sutures (figs. 18-20, 22) belong to the neanic stage, represented in figs. 12-15. They show the usual mode of division common in Ammonoids of the Jura and Cretaceous, tlie incoming of auxiliarv inflections on the primitive second lateral saddle and the primary bifid division of the first lateral saddle and first lateral lobe, the entire aspect of the siphonal saddle and its subsequent bifidity. Fig. 22 of PI. XI shows the peculiar prolecanitean aspect of the dorsal inflections before the end of the neanic stage, and illus- trates my previous statements with regard to the retention of ancestral characters by these internal sutures. Fig. 23 of PI. XI and fig. 1 of PI. XIII are of very nearly the same age, and give the beginning of the ephebic substages. The latter show that the primitive median marginal lobe of the primitive dorsal saddle becomes the large marginal dividing the full-grown first lateral saddles. This sutui-e also shows that the second lateral saddle has a trifid termination in some .specimens of this species. METOICOCERATID.E. 121 The sutures iu the two specimens here described as swaUovi are some- what abraded, liut their details of outline are sufficiently well preserved in different sutures to enable one to see how much simpler they are than in M. whitei. This simplicity of the marginals is not so great in some speci- mens as it is in fig. 2 of PI. XIII, since in the suture (PI. XIII, fig. 1) the second lateral is trifid and in fig. 13 the fourth lateral saddle is bifid. The number of inflections on the sides appears to be less in this species than in tvhitei, five only being present on both sides, with saddles at the lines of involution; and in the fossil shown in PI XI, fig. 16, there is the same numl)er, with a lobe at the line of involution. Local iti/: Grayson County, Tex.; Utah. Affe: Colorado epoch. 3Ietoicocekas gibbosum n. sp. Hyatt. PL XV, %s. 5-8. The single fossil upon which this species is founded could not be placed in an}- of the species here described under the same genus. It has stouter, broader volutions than any of these, and, instead of becoming more compressed as it grows older, continues the same rate of increase in the transverse diameters The involution is about the same as in M. sa-alJovi, but there are no nodes on the umbiHcal shoulders at any stage, although the alternating longer costse reach to the umbilical shoulders. Their greatest prominence is at a short distan(je ventrad of the umbilical shoulder. The costations are like tliose of the oldest staae of whitei, i. e., regularly long, prominent costfe alternating with short ones. The two outer lines of tubercles do not differ from those of other species. The sutures are intermediate between the simpler character of those of M. swallovi and the more complex outlines of those of M. whitei. The first lateral saddles and lobes have about the same general aspect as those of M whitei, but the auxiliaries are similar to those of M. swallovi, except that the second lateral saddle shows small marginals and a tendency to division on its outer side, which has not been observed elsewhere. The third lateral saddle shows iu some sutures of the left side a tendency to become divided, which is necessarily exaggerated in the drawing and which is entirely absent iu many sutures. 122 PSEUDOCERATITES OF THE CRETACEOUS. both younger and older than the one drawn. The dorsal sutures could be seen only from above and in a fragment of the cast of the last camera, which is not included in the figures given. It was evident that the antisiphonal lobes resembled those of M. swallovi and Heinzia in being elongated and considerably telescoped into each other. The saddles also were similar, especially the first dorsals, which were narrow, long, phvlliform, and deeply cut into by the marginals, as in Heinzia inatura. There was also a similar broad pair of second lateral dorsal saddles; these certainly had one marginal lobe and perhaps two, being perhaps trifid, but very flat on their bases. The remaining saddles were entire. There were apparently five saddles and four lobes oil the right side and six saddles and five lobes on the left side, corresponding to the differences in number of the external auxiliaries on the same sides. The overlapping of the sutures is noticeable in this specimen, but whether it can be considered characteristic of the species is doubtful. The whole diameter is 85 mm. The last volution on the face of the septum from the center of the venter to the line of involution is 50 mm.; the ventro-dorsal diameter is 35 mm. The amount of involution at this point is two-thirds of the breadth of the side of the next inner volution, being 17 to 27 mm. The umbilicus, in consequence of the smoothness of umbilical zones and the nonextension of the costfe internally, has a smootli, funnel-like aspect, entirely distinct from that of M. swallovi, although it is nearly of the same size and differs therefore from that of whitei in being much larger as well as smoother. Locality: Texas. Age: Colorado epoch. Metoicoceras whitei n. sp. Hyatt. PI. Xlll, figs. 3-.5; PI. XIV, tigs 1-1(», 15. BucMcerm .noallovi White, 1875, Geog. and Geol. Expl. and Surw West of lOOth Meridian, Vol. IV, p. 202, pi. 20, figs. 1 a-c. Buchiceras swallovi Stanton, 1894, Bull. U. S. Geol. Survey Ko. 106, p. 168, pi. '61; pi. 38, figs. 1-3. The external characteristics of this species, in comparison with M. swallovi, consist in more compressed volutions without such prominent nodes on the umbilical shoulders. They have nodes, but these are more a part of the costJE and less prominent, the .sides are consequently flatter than in swallovi. There is a decided tendency in the Texas specimens to METOICOCERATID.E. 123 have the umbilicus smaller and the inner row of the two outer lines of tubercles elongated loug-itudinalh' and parallel with the outer rows. The sutures are more complex at an earlier stage and remain more complex thi-oughout life as regards their marginal digitations. The first lateral lobes are also narrower and longer in proportion in the later stages than in swaUovi, and the infiections are more numerous at the same age, being from six to seven, instead of five or six as in sivaUovi. The youngest stage seen (PI. XIV, figs. 1,2) had a living chamber complete near the umbilicus and not quite three-fourths of a volution in length. Several specimens showed a completed living chamber near the umbilical shoulders and on the sides, and in adults it is much shorter, invariably one-half of a volution in length. The sides were smooth and flat at the beginning of the outer volution in this specimen. The costae appeared as shown in the figure and nodal termini were devel- oped on the last costation near the aperture. These wei'e also present in the specimen shown in fig. 4, but, as may be seen in figs. 2 and 5, these were not prominent as in stvallovi. The same is true of all of the seventeen specimens examined besides PI. XIII, fig. 4 The elongated second row of lateral tubercles found in fig. 4 is also perceptible to some slight extent in the specimen fig. 7, but is absent in younger stages and is not present at any stage in some specimens. This second row of tubercles may be very slightlv developed in some specimens, and the costse. are also much less pronounced and the venters naiTOwer than in those figured. The other two specimens show a much stouter form with brt)ader venters and more promi- nent costal. These can only be separated from true swallovi by their costse, flatter sides, and less prominent umbilical nodes. An old suture of this species is shown on PI. XIII, fig. 5. This was the basal suture of a fragment of the living chamber of a fossil of about the same size, probably, and age as the one shown on PI. XIII, fig. 4. The diff"erences of this suture appear to be considerable when com- pared with PI. XIV, fig. 8. The external characters of this fossil are equally decided, but the absence of the internal volutions and the variability of the sutures in this species does not justify the separation of this as distinct from ivhitei. The latter part of this living chamber and the whole of another larger fragment has huge fold-like costse that cross the venter, cutting it into waves. The costse are flat on the venter with abrupt forward edges. The ventro-lateral 124 PSEUDOCERATITES OF THE CRETACEOUS. tubercles and the .second lateral row disappear on these costa?. The decrease «»f the involution through shrinkage of the later diameters is greater in this than in the old age of the specimen shown on PI. XIII, fig. 4. Breadth of the side from line of involution to the siphonal saddle at the sutui'e figured is 65 mm. The length of the living chamber on the outside or venter is 190 mm. and apparenth' complete, and the breadth 7.5 mm. In the specimen shown in PI. XIV, fig. 7, the normal rate of increase is from 50 to 70 mm. in the same distance measured along the venter, and in the living chamber of the fossil shown on PI. XIII, fig. 4, which is of the same length on the venter it is from 70 at the base to 80 mm. near the end- In both of these old specimens the length of the living chamber and decrease in the rate of growth was therefore about the same and about one-half of what it was in the fossil shown on PI XIV, fig. 7, which was also an old specimen but was measured along the septate and therefore ywunger poi-tion of the outer volution. The increase by growth previous to this must have been greater still. The broadening of the venter noticeable near the aperture (figs. 3 and 4), the spreading of the costse across the venter, and the loss of nodes are the same in. all three of these specimens and show them to have entered upon the last or paragerontic substage or decline. The youngest suture examined in this species is shown in PI. XIV, fig. 3, fi-om the left side, and this has fully entered the ephebic stage and is already more complex than those oi swullovi at a nmch later age. The corresponding suture on right side of the same specimen is similar, but the third lateral saddle w^as quadrifid instead of bifid and the fourth lateral was more distinctly bifid and phylliform. The matrix of this fossil from Elm Fork, Tex., was a grav limestone, whei'eas that of the specimen shown (fig. 9) was a red clayey limestone, but from the same locality. The suture was much older, but nevertheless had simpler third and fourth saddles on both sides of the outer volution. The position of the suture of the specimen shown in fig. 7, given in fig. 8, is indicated in fig. 7 by a straight line near the venter, biit the sutures throughout this volution have the same outlines. This and fig. 10 are the most complex of the full-grown sutures observed in this species. Fig. 10 was taken from the left .side of PI. XIII, fig. 4, and shows the outlines of about the same age as in PI. XIII, fig. 8. The shell was stripped from a ])art of the fossil shown in PI. XIII, fig. 4, also, and the corresponding suture on that side also observed. In this way it was found MET0IC0CERAT1D.E. 125 that the sutures on the two sides differed considerably. They were alike in their first and second lateral lobes and saddles, but the third lateral saddles were simpler on the right side, the side given in PI. XIII, fig. 4, in having the marginals less distinct and the fourth lateral was entire instead of being bifid. The outlines internall}- were the same and there were seven saddles and seven lobes on each side, and saddles at the lines of involution. The difterences between the more fully developed sutures on the left side, those of the right, and the oldest suture showed similar degenerations, the saddles becoming much shorter and broader in propor- tion and the marginals less distinct. The table on page 126 gives an account of the variations observed in the sutures. It will be observed that the first lateral lobe is quite generally Ijirid, but in the largest specimen (PI. XIV, fig. 8) from Elm Fork, Tex., it is sometimes trifid. It is very obvious that tins character- istic may be capable of two translations, some of the first lateral lobes in this specimen being made trifid by a sHght enlargement and extension of the main terminal marginal lobe. The second lateral lobe varies from simple primitive form of bifidity to trifid without regard to age, but in most specimens it is bifid. The third lateral saddle is bifid or trifid without regard to age, but tends to become quadrifid in older stages. The fourth varies from entire t;> bifid or ti-ifid, but in most cases is bifid or trifid. The fifth varies from entire to bifid or trifid, but is in most cases entire, sometimes bifid but rarely trifid. The number of lobes and saddles on the sides varies from 11 to 14 in the earlv ephebic substages and from 13 to 16 in the full grown. No. 6 is taken from a fossil with a notably stouter volution, more prominent coarser costa?, and larger tubercles than any of its companions of the same size from the same locality, Elm Fork, Tex The whole diameter of this fossil when complete was probably not less than 63 mm. and the living chamber of the usual length, a little over half of a volution. Unluckily, like all others of this species, the aperture has been badly broken and the rostrum could nut be observed. I at first thouffht this exceptionally stout and more coarsely ornamented specimen must be a different species, but the sutures, when laid bare, were identical with others here described as M. tvhitei, especially close to that given on PI XIV, fig. 10. 126 PSEUDOCERATITES OF THE CRETACEOUS. Variations observed in sutures of 2Ietoicoceras whitei. [The number of saddles and lobes represents one side only. All except Nos. 11, 12, and 15 are from Elm Fork, Hortons mill, Dallas County, Tex.; No. 15 is from Utah; no locality is given for Nos. 11 and 12,] Speci- men. 10. 11. 12. 13. 14. 15. Side observed. rLeft... iRight . fLeft... 2 . X iRight . ' fLeft... ^ iRight . fLeft... iRight . ! fLeft... ^ |lRight. fLeft... IRight . fLeft... ' jlRight . I fLeft... ^ |lRight . Left . . . Length of suture line or breadth of side. I Right fLeft.. IRight fLeft.. iRight Left.., \Right fLeft . . . iRight , fLeft... IRight , J Left... I Right 10 13 17 17 23 23 28 31 34 35 39 45 55 65 70 First lat- eral lobe. f Bifid. I. .do . fBifid? I (?) ^Bifid . l (?) (?) (?) (?) (?) fBifid. I (?) I ^'^ I (?) I ^'^ iBifid. I *'^ I (?) f Bifid . I.. do . f..do . I. .do . f..do ., I (?) /^Bifld., .do ., ..do . (?) fBifid . I.. do . Second lateral lobe. Third lat^ eral sad die. Trifid ...do . (?) (?) (?) (?) (?) (?) (?) Bifid. ...do . (?) (?) (?) (?) Trifid (?) (?) Bifid. ...do . ...do . ...do . (?) (?) Bifid . ...do . ..do .. (?) Bifid. ..do.. Trifid ...do.a ...do . ..do . ...do . (?) (?) Trifid." (?) Trifid . Bifid!/. (?) Bifid.. (?) (?) Bifid !-. Trifid" ,..do.n. Bifid . . ...do .. Trifid . ...do.n. ...do .. ..do .. ..do.''. . .do. f. Bifid <-■. (?) 4-fid .. ...do.9. Fourth Fifth lat- lateral eral sad- saddle. ! die. Bifid.. ...do .. Entire? ...do.?. Trifid . (?) (?) Trifid . (?) Bifid . . ...do .. (?) Trifid? (?) (?) Trifid . (?) Entire. ...do .. ...do .. ...do .. ...do .. ...do .. (?) Bifid . . Varia- ble..r' Trifid . (?) Trifid . Entire. (?) (?) (?) Entire. (?) (?) Trifid . (?) Entire ...do .. (?) Entire. (?) (?) Bifid.. (?) Entire. ...do .. ...do .. ...do .. ...do .. ...do .. (?) Entire. ...do .. Bifid., (?) (?) Bifid . . Entire. Number of saddles and lobes on sides. j Number >of saddles j and lobes on dor- sum. ' 'I 11 \> (?) j (?) ,' (?) ' (?) , 11 / (?) \ (?) i' (?) ' " } (?) ' (?) i 13 :/ (?) 13'? 16 16 13 13? 13? 13? 15, 15 / 15 (?) 13'; 13 (?) (?) (?) (?) (?) (?) (?) 10 (?) (?) (?) (?) (?) (?) (?) Figured. PI. XIV, figs. 1-3. PI. XIV, figs. 4-6. PI. XV, fig. 15. PI. XIV, fig. 9. PI. XIII, figs. 3,4, and PI. XIV, fig. 10. PI. XIII, fig. 5. PI. XIV, figs. 7,8. a Beginning to become quadrifid, i. e., having four minute marginal saddles by division of one of the bifld marginals. ^\Vith a few minute digitations beginning to appeiir. c With three other very minute lobes, five marginal lobes in all. dDistinctly trifid. < Obscurely trifid. /Some entire, others obsouroly trifid. uWith a number of small marginals just beginning. METOICOCERATID.E. 127 lu all of these specimens the hrst lateral saddles were of very nearly the same general character, decidedly deeply bifid, even in the youngest stages recorded, and with both arms subdivided by one or more marginal lobes; the second lateral saddles were also complex at all stages observed, and one small specimen not recorded in the table, with suture lines on the last volution running from 12 to 18 mm., showed the same facts. This has bifid first and trifid second lateral lobes, with quadrifid third lateral saddles on both sides. A bifid fourth is visible on the right side when the volution is less than 12 mm. This same saddle with a bifid base is the only one visible in another fossil with a suture line of about 8 mm. It is evident that the law of variation in the sutures is that lobes and saddles increase in variability of outlines and in number progressively from the venter toward the dorsal lines of involution, the so-called auxiliaries or derivatives of the primitive second lateral saddles of the young being far more variable than the first lateral saddle. Locality: Kanab Valley, Utah; Elm Fork, Dallas County, Tex. Age: Colorado epoch. Metoicoceras acceleratum n. sp. Hyatt PI. XIV, tigs. ll-U. I at first thought this to be the young of the species described by Whiteaves as Placenticeras liardense, but the figures given b}^ him merely indicate that the venter had continuous costte across it. The condition of his fossils was, however, such that he did not see the venter, and this can only be inferred from the lateral aspect as given in his drawings. Apparently there were no tubercles on the sides in the full-grown specimen, and the umbilicus was about the size of that of M. ivhitei and not so small as in this species. There were no nodes nor prominent costse near the umbilical shoulder in this fossil, and the two outer rows of tubercles were much less prominent than in the preceding species. The venter in the first half of the outer volution resembled that of M. whitei at an earlier age on the first quarter of the outer volution of the specimen shown in PI. XIV, fig. 1 , but with less decided tubercles, and on the latter half of this volution it is changed as the venter is in the old age of M. whitei. That is to say, the costse that cross it are prominent and flat, but not channeled nor concave. The costse on the sides are not so prominent and coarse as in 128 PSEUDOCERATITES OF THE CRETACEOUS. whitei. There are more of tlieni, and imly the hist begin to reach entirely across the sides. There is a signioidal channel on either side that does not reach across the venter. This is a characteristic occurring- also in M. liardense, but not in other species. This occurs close to what must have been the edge of the aperture, since the hving chamber is considerably over tlu-ee-fourths of a volution in length and was probably a little longer when complete. The black line shows the position of the basal septum of the li-viug chamber shown on the opposite side of the fossil figured. Locality: Elm Fork, Horton's mill, Dallas County, Tex. Age: Colorado epoch. HEINZIID^. The members of this famih' are easily distinguishable from the typical Pulchelliidse by the possession at some stage of elongated, usually double, but more or less connected tubercular terminations on the ventral ends of the lateral costse. All of the foi-ms so far known have coarser and more complete lateral costse than are usual in Pulchelliidpe, and there is, especially in primitive forms, a tendenc}^ to the development of stouter volutions, with less involution and consequently wider umbilici. The average size is larger, and the development is very distinct in all forms, so far as known. The young are stouter, less involute, and have costse con- tinuous across the venter. The tubercles appear upon these costse in two lines of single tubercles, and then subsequently two rows are developed ujjon the outer sides of these that remain more or less closely connected. The lateral costae are similar to those of Pulchelliidfe, but sometimes a median or an inner row of tubercles or both appear in the later stages. The ventral channels are apt to be real channels furrowing both the costae and the intercostal spaces on the venter, and in the young and in primitive forms are apt to be narrow and smooth. The sutures are similar to those of Pulchelliidaj, but as a rule have fewer and larger saddles and lobes, and the outlines more complex at the same comparative age, judging from the size of the casts. The development is so distinct from that of Pulchelliidse in some species of Heinzia that if it were not for the fortunate accident that placed one specimen of Heinzia matiira in my way, I could not have offered any rational suggestion as to the true relations of this family. The development of Heinzia matura, however, shows, as stated below, a form that in the HEINZIID.E. 1 29 young- is involute, smooth, and compressed with a rounded venter as in the young of Pulchelhida?. Then it has a faint hne of ventral tubercles and flat venter followed bv a true Pulchellian stag-e with channeled venter bordered by single tubercles. In other words, at this age the species is like PuJcheUia except that the tubercles are not elongated crests. The ephebic stage shows the usual terminal double row of tubercles of the Heinziida?. The conclusion from this evidence is that the Pulchelliidae probably arose from Heinzia or some ver}- similar form through the increase of compression and involution and from the prolongation of the smooth larval stages, the suppression of the preliminary lines of ventral tubercles in the young and the tendency in later stages to suppress the second lateral lines of tubercles. This inference acquires some support also from the fact of the earlier appearance of Heinziida? in the Neocomian. We can in this way account for the communal resemblances of these two families in their adult forms, costse and sutxires, but it must be borne in mind that the evi- dence upon which this inference is based is not by any means complete. The evidence with regard to the connection and genesis of forms is less complete than in the Pulchelliida?, but the following diagram gives the apparent relations of the genera so far as the ontogeny at jjresent known indicates these: Metoicoceras Gerhardtia Carstenia -Heinzia Cheloniceras HEINZIA Sayn. Sayn" defines this genus in the following terms: "Les espfeces qui se rattachent aux PulcheUia subcaicedi et provincialis sont nettement caracter- is^es par une ornementation vigoureuse, visible dfes les tours embryonnaires, un accroissement en ge'neral moins rapide, des sutures le plus souvent tres the forward terminations of the costse. This is also observable in Uhlig's figure. On splitting this specimen I succeeded in exposing three substages of neanic age. The first substage showed faint costa? that crossed the rounded venter, the form being at this time rounded, with gibbous sides and oj)eu umbilicus. Then faint tubercles appeared, the venter still remaining rounded between them. These tubercles in the next su^bstage became more prominent, and the venter between them became flattened. The costae became more prominent at the same time on the outer half of the side and made a slight forward liend on to the venter. Soon after this a very faint, narrow, linear depression indicated the beginning of the ventral chaiuiel. I was not able to discover at what age the second range of tubercles began to come in nor their exact position. The volution is gibbous on the sides throughout these early stages and is a' rather stout young form with an open umbilicus. Locality: Escragnolles, France. Aye: Barremian. Heinzia matura n. sp. Hyatt. PI. XV, figs. 12-18. This species is allied to that described alcove by Sayn. It is similar in its compressed form, in the amount of involution and in the broad ventral channel, and in having a row of tubercles on the umbilical shoul- ders. The costaj are, however, much broader and have the double external termination of the group of Heinzia. This termination is, however, not distinguishable on the earliest part of the outer volution, but is well devel- oped on the third (piai-fer of this volution. This termination is seen in this specimen to be a modification of the ends of the costa?, and it is not due to tlie a})i)roximation and coalescence of an inner row of tubercles with the outer row. The shell is preserved on one side of this specimen and shows HEINZIID^E. 133 the same marking-s as on the cast. The }';oaiig is much flatter and increases faster in the abclomino-dorsal diameters than in other s^jecies of Heinzia and remains smooth until a later ag-e. The tubercles appear also later on the venter, and there is a flat ventral zone for a more prolonged stage than in H. jiroviticiaUs, and the ventral channel appears later. The umbilical tubercles appear on the last volution figured and are at first single. Then they probably become [double] by the development of two other roA^s of tubercles near the ventral lines, but this was not actually seen on the specimen. Locality: Escraguolles, France. Ar/f: Barremian. Heinzia ouachensis (Coquand). Pulchellia oioichtnsix Sayn, 1890. Ann. Soc. d' Agriculture de Lyon, ((th series, Vol. III. p. 1.57, pi. 1. tig. 1.5 (not fig. 14). This species, described as a Pulchellia by Sayn, is an involute com- pressed form probably in the same genetic group with H. matura. This is shown by the ventral channel and costse and tubercles on the umbihcal shoulders. It has not the broad double terminations of the costaj observed in H. matura. Fig. 15 is probably a true PulcheUia, and is cited under that generic name as P. kiliani. Locality: Djebel-Ouach, North Africa. Age: Barremiau. CARSTENIA n. gen. Hyatt. This remarkable group has, as shown by Karsten's figure of Carstenia lindigi in the latest neanic or early ephebic stage, coarse costpe with double terminations liecoming dichotomous at the middle lateral line and havino- a line of nodes at their junctions. These are continued later on the single costse when these appear. The arising of the double line of outer tubercles close together on the ventral line is also shown in this figure. The form is stout in the type mentioned above and similar to that of Heinzia provincialis, but in the Carstenia (Amm.) caicedi Karsten it is more involute and com- pressed. The ventral furrow in Carstenia lindigi in the young is narrow and similar to that of Heinzia, but later it broadens and becomes similar to 134 PSEUDOCERATITES OF THE CRETACEOUS. that of Gerliardtia. This occurs in an earlier age in Carstenia caicedi. Descriptions are wholly taken from Karsten's figures." Carstenia subcaicrui (Karsten). C. subcaicedi (Karsten) is described ))y that author as having heavy coarse costse bifurcating like those of caicedi and, if his small figure represents the young or a primitive dwarfed form of this group, it shows how very distinct its development must be as compared with that of other genera. Carstenia ? tuberculata n. sp. Hyatt. C. f tuberculata (Pul. provincialis Gerhardt) '' is described by that author as identical with lindigi Karsten. It is, however, less involute, and, although having similar quadragonal volutions, has costa? like those of Gerhardtla and there is no median lateral line of tubei'cles. The sutures are more like those of Metoicoceras than of Heinzia iwovincialis. It is jjossible that the development of this species may show it to be more nearly related to Metoicoceras than to Carstenia. It has, however, the peculiar channeled bases of the second row of tubercles on either side that have been found so far only in this last-named genus. All of these have been supposed to be of Barremian age. Its characteristics seem also to ally it decidedly with such forms as Heinzia provinciaUs, and to indicate a common origin for all of these genera in some primitive form with similar but more tuberculose volutions. It is obviously a more primitive form than Heinzia, which has more compressed and often more involute shells and retains in its latest stage the form and aspect of the young of H. iwovincialis and of the earlier neanic stage of Metoicoceras sivallovi. The resemblances to Gerliardtia are also close, as may be seen on Gerhardt's plates, and its form is similar to the young of Carstenia caicedi as figured hy Karsten. These affinities and its obviously primitive larval characteristics show it to be the nearest approach yet found of the probable genetic ancestor of the Heinziidie. «Geol. de I'ancienne Colomb. Venez. Nouv. Gren. et Ecuador. Berlin, 1886. SKreidef. in Columbien: Neues Jahrbucli fiir Min., Oeol., und Pal., Beil.-Bd. XI, 1897-98, p. 1.52, pi. 2, fig. 8. HEINZ1ID.E. 135 Carstenia galeata (d'Orbigny). Ammonites galeatus d'Orbigny, 1842, Voyab\xm, 1698, Zeitschr. Deutsoh. geol. Ge^ell., Vol. L, p. 197. A cast of one-half of a volution in Museum of Comparative Zoology from Professor Whitney shows ephebic stage. The wiiole diameter, partly 154 PSEUDOCERATITES OF THE CRETACEOUS. estimated, is 69.5 mm., the outer portion of this vohitiou, partly estimated, is 42.5 mm., the umbiUcus is 5 mm. and the opposite i)art of same volution is 22 mm. The shell is present on the venter but not on the line of involu- tion. Greatest transverse diameter of outer volution is 25 mm., the iimer part is 11 mm., both through the umbilical shoulders, shell on one side and not on the other side. Probably shell would have made the difference of 5 mm. in eacli case. This is a compressed shell, closely similar in aspect to Enr/onoceras nddcm and the ephebic smootli stag-e of Protengonoceras F emarginatum, but the involution is greater; the costations in this stage are fainter, but can be plainly enough seen both on cast and on the shell in a cross light. Thev are less than in Gabb's figure, but the form of venter and aspect of shell, including amount of involution, shows that we are dealing with Gabb's' species. There are also no tubercles on the umbilical shoulders. The first large fold is partly present on the broken edge of the outer volution in the small fragment figured, showing the beginning of the gerontic stage. The venter is decidedly concave with slight ridges on either side. This form of venter is found in the neanic stage and the whorls, although stouter, are similarly compressed when the whole diameter is onlv 13 mm. At diameter of +4 mm. this venter, although almost as broad as the trans- verse diameter, is alreadv like that of the adult, but may be a little flatter. Other details could not be seen. It is obvious that the young acquire the concavity and sharp lateral ridges of the ventei' in an early neanic substage at a time when the volution becomes flattened on the lateral zones. The form is then obviously like some stouter and less involute forms of this genus not yet discovered. The sutures are very slightly flexed apicad; the saddles and lobes closely similar to those of Metengonoceras. The venter is slightly asymmetrical; the first pair of saddles on the riglit are divided by a very slight marginal lobe. There are nine saddles and eight lobes on the right side, the seventh saddle alone being bifid. The marginal lobe dividing this saddle appears on the earliest suture of this volution. Lobes on the left side of a more advanced stage show that this simplicity is due to age. A larger specimen, same locality, in the gerontic stage, is 108.5 mm. in diameter and has the shell preserved. Outer part is 57.5 mm., umbilicus ENGONOCERATID.E. 155 7.5 nan., and opposite side same volution 46.5 nun., no shell present. The greatest transverse diameter of the volution is 30 mm., and of thesmaller part opposite is 22 nun. The shell is marked by bands of growth and fold-like obscure costse wliicli appear in the gerontic stage. These terminate at the umbilical shoulders, and along the centran surface of tlie lateral aspect have very broad swellings and then subside into the flat general surface toward the periphery. The venter is slightly broader than in the ephebic stage above described and the volution stouter, owing to the development of lateral swellings and the slight decrease in the involution due to old age. The umbilical shoulders and the umbilical zones are abrupt instead of being rounded and sloping as in the adults. The living chamber is complete near the line of involution and is about one-half of a volution long internallv and apparently about the same externally when restored. The concavit}- of the venter is maintained for one-half of the length of the living chamber. Beyond this it could not be followed, but there are some indications of the possible rounding of the venter in extreme age. The sutures are cpiite distinct from those of the ephebic stage in the s})ecimen above described. There were eight saddles and seven lobes to the umbilical shoulders, remainder on the umbilical zones being concealed. The interesting fact, however, can be noted that in this gerontic stage new saddles and lobes were not added as the sides broadened. The increase of the sides was met by the broadening out of the saddles. The first laterals were very broad, the second and third had not changed much, but Ijegin- niug with tlie fourth they became irregularl}- broader toward the vimbilicus, and the seventh was 6 mm. in breadth, whereas the sixth lobe was only about 1 mm. long. The lobes remained about the same as in the adult stage. The form of the volutions, smc»oth concave venter, slightly costated sides, with large folds only in gerontic stage, and primitive sutures all show that this is a species like the similar stag-es in the development of tuberculated forms in Metengonoceras and also similar to the young of Placenticeras. It is, however, a deeply involute shell and is not therefore by an)' means the most primitive form of its own subseries. It indicates the existence of a distinct subseries having similar smooth concave venters and less involute or more discoidal shells, which in the gerontic stage become stouter with 156 PSEUDOCERATITES OF THE CRETACEOUS. gibbous sides and have also comparatively flattened or rounded and much wider venters. Having- been loaned through the kindness of Dr. Pilsbry another sjjeci- mon of this species from the collection of the Academy of Sciences, Phila- delphia (PI. XVII, fig. 20), I can state the following additional particulars: The diameter is about 82 mm., partly estimated. The living chamber is one-half of a volution in length on the periphery, but is much shorter on the line of involution, owing to the great apical trend of the aperture. This has a broad but very slight sinus on either side and apparently no lateral crests on the sides that could be separated from the rostrum. This last, however, was broken and could not be decisively determined. The specimen is in its gerontic stage and upon the inner parts of each side has four heavy folds which disappear near the venter. The bifidity of the internal saddles is variable, since in another specimen in the collection ot the Museum of Comparative Zoology the sixth saddles were bifid. Locality: Arivechi, Sonora, Mexico. Age: Fredericksburg group, Comanche series. Protengonoceras planum n. sp. Hyatt. PI. XVIII, tig-s. H-9. This species is described from a fragment which would be ordinarily insuificient for diagnostic work. The greatest length of this piece is only 22.5 mm., the ventro-dorsal diameter of the volution 14 nnn., the greatest diameter at umbilical shoulders 5.5 mm. Nevertheless, the cast is perfectly smooth, the sides flat, and the venter, which is only 1 mm. in width, is also smooth, concave, and bicarinate. These characteristics, especially the attenuated venter and smooth sides, distinguish it quite sufilciently from the preceding species to justify specific separation, lliere are ten saddles, all narrow, the first symmetrically bifurcated, as in other forms of this genus and Engonoceras. They are entire and from second to eighth more or less club shaped, but the ninth is broader and bifid. The tenth and eleventh are entire, occupying the umbilical zone. The dorsal zone of impression has six saddles, counting the outermost one above m,eutioned (PL XVIII, fig. 9). There are ten narrow zygous external lobes (PI. XVIII, fig. 8) on the right side. The first is club shaped and entire, the second to the fifth similar, but faintly trifid. The sixth to the tenth are shorter and decrease ENGONOCERATID^. 157 iu length to the Hue of involution and are entire. Ou the opposite or left side there are ten saddles and eleven lobes. The tenth saddle is completed, and there is a small lobe on the line of involution. The first saddle is narrower and the eighth and ninth saddles broad, and both similar to the ninth on the right side in being bifid. On both sides the first five lobes are long, and the same change occurs in the shortness of the sixth and remaining lobes and saddles. The matrix is similar to that which occurs in the Colorado formation at Horton's mill, Dallas County, Tex. Locality: Texas. Age: Stanton suggests Upper Cretaceous from the matrix. Protengonoceras ? EMARGINATUM (Cragiu)." Sphenodisciis emarginatus f Cragin. 1S93, Geol. Surv. Texas. Fourth Ami. Rept., p. 245. This species is described as having straight distinct ventral channel at the diameter of 90 mm. and also as having two rows of feeble tubercles, one on the umbilical shoulders and the other midway on the lateral aspect. The bilobed saddles mentioned by Cragin indicate a more complicated suture line than occurs in Protengonoceras as far as known, but the condition of the venter indicates that genus. Not having seen any specimens of the species, I can not say positively that it is a member of this genus. LocaJitij : 2 miles south of Pleasant Point, Tex. Age: Comanche series. Walnut beds. ENGONOCERAS Neumayr. Although the descriptions and figures of Engonoceras pierdenale led me to believe that this species had an acute venter, Bohm'' has stated, after studying the fragraentar}- originals, that these had truncated concave venters, bordered bv ventro-lateral ridges or elongated tubercles, and that the species upon which the genus Engonoceras was founded, Amm. pierdenalis v. Buch, closely resembles his Eng stolleyi. The two fragments figured by Bohm do not show conclusively that this is the fact, but it appears to be safest to follow him in the eff'ort to give stability to von Buch's name and Neumayr's geims. Von Buch's and Roemer's descriptions lead to the belief that the 0 See p. 177, where this species is referred to Engonocenis. — T. W. S. ^Ueber Ammonites pedernalis v. Buch: Zeitschr. Deutsch. geol. Gesell., Vol. L, 1898, p. 183. 158 PSEUDOCERATITES OF THE CRETACEOUS. shell casts they described had acute venters, but this is probably an en-or. In studying this group of fossils such a mistake is easily made, owing to the simplicity of the sutures, the narrowness of the flattened venters, and smooth- ness and symmetrical aspect of the fossils, although considerably worn and altered by abrasion. The presence of three distinct lines of nodes, the flatness and nodose edges of the venter throughout the earlier and ephebic stages, the broad and often zigzag outline of the venter in the geroutic stage, caused by the extra development of the outer line of alternating nodes, enable one to separate the species of this genus readily from those of Metengonoceras, notwithstanding the close similarity of the sutures. The young during the neanic stage are compressed, involute, and smooth, with concave venter and form like Pro- tengonoceras. Von Buch and Neumayr both describe the principal saddles of Engonoceras pierdenale as bifid, and this occurs in the species here sup- posed to represent Engonoceras, but does not occur, so far as known, in Meteugonoceras. All specimens so far seen have been casts, either entireh' naked or with only the nacreous layer partly preserved. The attention of collectors is called to the fact that some of the species bear no convincing marks of having been autochthonous members of the faunas in which they are habitually found. This genus differs from Neolohites only in having denticulated lobes, if the figures of tlie sutures heretofore given correctly represent their outlines. Engonoceras belviderense (Cragin). PI. XVIII, figs. 4, 5. Ammonites belvideremis Cragin, 1894, 1895, Am. Geol., Vol. XIV, pi. 1. tigs. 3-5; Vol. XVI, p. .369. BucMceras {Sphmodlscnif:) helmidereiim Cragiu, 1900, Colorado Coll. Studies, Vol. Vm, p. 27. Through the kindness of Professor Cragin I have seen some specimens of this species, and one of these has been given in the figure. This alone was not much crushed, but the sutures could not be made out. The aspect is similar to that of Eng. uddeni, but the sides and venter ai-e flatter and smoother. There are similar nodes on the umbilical shoulders and those on the edges are alternate; there are nascent folds on the outer part of the aides. It reaches a larger size than other forms before it begins to acquire ENGONOCERATID^E. 159 the usual gerontic characters — that is, before the venter becomes convex and more or less zigzag- in outline. The type of Cragin's species is the small specimen referred to above. This has sutures with numerous small saddles closely set on the suture line, and, so far as could be seen, one of Cragin's fossils of the same lot with that figured had similar sutures. Cragin describes this species as having a row of tubercles that mav be developed on the inner ends of the low folds or costpe occupying the outer half of the sides. There are some very obscure signs of the existence of such markings in these fossils also. These are doubtful even to the touch and are not visible to the eye. This may be owing to the condition of the fossils. Locality: Belvidere, Kans. Age: Champion bed and Kiowa shales, probably near base of Washita Comanche series, Lower Cretaceous. Engonoceras uddeni (Cragin). PI. XIX, tigs. !-•). Sphenodiscus helviderensis var. uddeni Cragin, 190t), Colorado Coll. Studies, Vol. VIII, p. 30. pi. 1, tigs. 3, 4. A fragmentary cast in iron pyrite, No. 23147 U. 8. National Museum, PI. XIX, fig. 4, 5, shows a few of the last sutures and a portion of the living chamber. The diameter, partly estimated, is about 82 mm., the outer volution is 44 mm., the undiiHcns 8 mm., the same volution opposite from line of involution to venter 30 mm., no shell being jj resent. The form is compressed and highly involute, l)ut slightly stouter than in the more compressed eman/inatum. There is only one line of nodes, those on the iimbilical shoulders. The costte are fine, and like elevated bands of growth gathered to a focus at these nodes. They are sigmoidal with single fine lines between the nodes, externally more pronounced folds appearing in the later gerontic substage, but no nodes are present on this jiart in this specimen. The venter is flattened until near tlie last part of the living chamber, which is distorted through compression. The part of the living chamber preserved indicates that it was not less than half a volution on the umbilical side. The ten lobes and eleven saddles on both sides are very similar in outline to those of emarginatHm. The seventh and eighth lobes on l^otli sides are bifid. 1(30 psp:udoceratites of the cretaceous. The ventral and also the fii'st lateral saddle are asymmetrical. These have the usual form but are ratlier narrow. The internal parts of the sutures are deflected orad toward the umbilical shoulders so that they rise materially, giving them a pecular aspect in this s])ecimen. The lobes are similar to those of emnrgmatum, but are narrower and shorter and the saddles broader, and shorter in proportion. The second to the sixth saddles are entire, the seventh to the ninth bifid, and tlie tenth saddle is on the line of involution. The sutures are the same on both sides of this specimen. The lobes are irregularly bifid. There is a frag-ment of a larger size consisting of one-fourth of a o i^ o volution with stouter proportions, labeled "Locality 1490 U. S. Geological Survey, north of Pottsboro, Tex., Upper Comanche (GraysonJ," that may belong to the same species, Ijut the sutures and aspect are distinct enough to belong to a diff'erent species." The inner line of large nodes and the median lateral are present, Ijut no outer line, and there are similar distinct costations. The venter has a similar outline also, but the specimen being larger and older, the venter is more rounded. The sutures are similar, except that the inner arm of the first lateral saddle is much narrower and entire, the outer arm is distinctly bifid, making the whole outline approximately trifid, the remaining saddles are longer and distinctlv phylliform as in SpJieiiocUseus, and the lobes are correspondingly Ijroader apically as in that genus. These effects may perhaps be due to the greater age of the specimen. There is apparently the same immber of lobes and saddles. There are nine saddles visible on the broken end, right side, and there may be one more, making ten saddles and nine lobes. A fragment obtained from Dr. F. A. Udden, locality northeast of Little River station. Rice County, Kans., is the original specimen used by Cragin and is figured below on PI. XIX. It is in fine state of preservation, being fossilized with iron pyrite. The breadth of the side is 53 mm., the greatest transverse diameter is at about one-third of the bi'eadth from the line of involution and is 20.5 mm. The venter is very narrow, about 3 nun. in 1 jreadth ; it has no obvious nodes, but, as in the type, faint undulations may be felt with the finger on the ventro-lateral angles. The sutures are quite different, but have the same general character. The first lateral saddles are quite distinct on the two sides, owing to the asymmetry of the ventral lobe. "Figured as Engonoceras retardum n. s|i. Hyatt, PI. XV, figs. 15-17. ENGONOCERATID.E. 161 The sixth saddle on the left side is bifid; the seventh is broad and STmmetrically and deeply bifid, looking like two entire saddles; the eighth has a large, slightly bifid, onter and a tongue-shajjed innei' arm ; the tenth is bifid. The ninth and tenth can be reckoned in several difierent ways on account of the peculiar forniation of the lobes, either as above, or tlie inner arm of the ninth be called the tenth and what is here named the tenth can be classed as the eleventh, or, on account of shortness of the lobes, the whole may be considered as a single broad saddle with three arms, the outer and inner arms bifid and central arm narrow and entire. The eleventh saddle is trifid and broad, ihe twelfth and thirteenth entire, and the last is on the line of involution. On the right side the first lateral saddles, on account of the asymmetry of the ventral lobe, are narrower and the second is much reduced. The second to the seventh are entire, the eisrhth and ninth are svmmetricallv bifid, the tenth to the thirteenth are entire. The twelfth and thirteenth saddles alone correspond or are symmetrical, bilateral on both sides of the body. The lobes have a ten- denc}' to become irregular at their terminations and are long and narrow on both sides and more alike than the saddles. There is also a large fragment of an example of this species in its "erontic stag'e, or of an undescribed soecies, associated on same mount with E. snhjecfum (No. 10756 Collection Boston Society Natural History). The diameter from line of involution toward venter as far as fragment goes is 68 mm. There are only a few millimeters wanting externally, since part of the first saddle is present. There are apparently nine saddles only on the side, all entire except the seventh, eighth, and ninth, which are bifid. The first to fourth lobes are long and narrow and the saddles stout but phylliform. These sutures belong obviously to a very aged shell, since out of nine sutures visible the eighth is the first that does not slightly overlap and the last four overlap 2:)rogressively more and more. The absence or very slight development of the outer lines of nodes and the absence of distinct ridges on the ventro-lateral edges of the venter distinguish this species from E. suhjedum. The sutures of these two run closely together, although the saddles and lobes of this form are somewhat stouter and broader at tlie same age than in E. suhjectum. Locality: McPherson County, Kans. Afje: Comanche series, Kiowa shales. MOX XLIV — 03 11 162 PSEUDOCEKATITES OF THE CRETACEOUS. Engonoceras serpentinum (Cragin). PI. XIX, tigs. 7-14; PI. XX, figs. 1-5. Sj)/ienodtsciis iehild^'ensia var. serpentinum Ci'agin, 1900, Colorado Coll. Studies, Vol. VIII, p. 31, pi. 2, figs. 4-6. Three casts of this species (Loc. No. 1489) are well preserved in a matrix of hematite. The diameter of one (1489 b) is 58 mm., the vohition is 29 mm., the umbilicus 7 mm.; the same volution opposite, measured from lines of involution to venter, 22 mm., no shell being present. The involution conveys the larger part of each outer whorl, but the internal volutions are plainly visible in the umbilicus and the involution is obviously much less in the younger stages than in adults. The volutions are much compressed. The venter is, however, flattened and slightl}' con- cave in the ephebic stage, and in the gerontic stage it becomes asymmetrical and sinuous through the development of the large tubercular terminations of the alternating costsK. In the ephebic stage the costse are sigmoidal and only slightly developed; in the gerontic stage these become broad on the outer parts with an external and internal line of nodes, and become obscure internally or umbilicad of the second row of nodes, but they ai'e obviously confluent to the internal or third line of smaller nodes on the umbilical shoulders. These nodes, like tlie costse, come in on the casts at a late ephebic substage, the side of the yoimger whorls being smooth. The tubercles of the outer line in tlie one specimen (1489 b) are sharper and the costse at the points convergent, whereas in the second specimen from the same locality the latter broaden out and the tubercular terminations are more elongated This, however, resembles those of the other specimen in the ephebic and anagerontic substage, the marked elongation coming in with the metagerontic substage. A similar disposition to broadening out of costa^ is also observed in the larger specimens in extreme age, but is not so marked and the venter also remains narrower. The living chamber is not complete, but it must have been about one-half of a volution in length on the line of involution. Other specimens show the same, but none give the outer margins. The inner lines of tubercles remain close to the umbilical shoulder, receding outwardly very slightly in extreme age. ENGONOCERATlDvE. 163 The variation between different specimens in external aspect of the casts is not great except in the gerontic stage owing- to the greater or less development of the nodose costations, bnt the variations in the sutures are such that no two specimens are alike. The fourth suture on right side of figured specimen has eleven lobes and ten saddles, and is only slightly curved apicad. The arms of the ventral lobe are seen cutting deep into the lateral aspect. The inner branch of the first lateral saddle is broad, entire, and club-shaped, as are all other saddles, except the ninth and tenth, which are bifid. The deptli and size of the lobe that divides what is here assumed to be the first lateral is so like other lobes that it is not always easy to determine whether it is a marginal or realU' tlie first lateral lobe. The lobes are all clubbed; that is, narrow orad and swelling-out apicad, and from first to seventh show very faint digitations or indications of from three to four very minute incipient marginal lobes, the fifth sliowing the equal and the remaindei- tlie unequal numbers of these. Specimen 1489a has short lobes and corresponding saddles like the above, but narrow outer branches to the first lateral saddles and arms of ventral lobe hardly apparent on the lateral aspect. There are eleven lobes and ten saddles easily distinguishable, i. e., not overlapping and similar to those of the first specimen, but saddles narrower outwardly and broader inwardly, and, what is more remarkable, the seventh, ninth, and tenth are bifid, the eighth, which is bifid in the first specimen, being entire in this. Specimen 1489c has such distinct sutures that one hesitates to place it in the same species with those marked 1489a and 1489b. The sutures are more deeply curved apicad, the outer five saddles and lobes longer and narrower, and the inner ones broader and flatter. There are, however, eleven lobes and ten saddles visible, as in the otliers, and the age is about the same. The sutures are, however, closely approximated, so that the lobes slightly overlap even in the ephebic stage and form columns except along the lines of tlie first to the second. The ninth saddle alone is bifid, all others being entire. The discoidal aspect of the young in the umbilicus can be plainly seen in this specimen. The sutures on the left side have the same general character, but differ in details from those of the right side. The outer saddles are alike, but the inner ones are narrow and more numerous. 164 PSEUDOCERATITES OF THE CRETACEOUS. The fragments from Denison consist of an almost entire gerontic living chamber and one somewhat more imperfect one of the same age, a smaller fragment (tf })art of ephebic living- chamber and last suture. This last shows that in the ephebic stage the venter is smooth, narrow, concave, and has no tubercles, but is bordered by two smooth ridges. There are nine lobes and nine saddles, the seventh and eighth saddles being bifid. The line of involution is occupied by a minute lobe, as it is also in other specimens. There are five dorsal lobes between this and the antisiphonal lolje on each side. The first dorsal saddle next the antisiphonal is entire, the second and fifth are bifid, the rest are entire. The third dorsal lobe was l^ifid, the remainder on both sides of this were entire and nari'ower. The antisiphonal lolje was narrow and bifid. The sutures of an early ephebic or late neanic substage in one of these showed that the notation of the saddles in this group is correct, and that the first lateral has, as stated, two unequal arms, the inner l)eing really an adventitious saddle derived from the inner side of the first lateral. The outer saddles and lobes are similar in outline to those of some specimens from northeast of Gainesville, but tlie inner saddles and lobes are shorter and broader. A specimen from Denison, kindly lent me by Prof. F. W. Cragin [is also figured and is probably one of the types of his variet}* serpentimis now raised to specific rank]. This species is distinguishable from others by the extremely late stage to which the protengonoceran venter — i. e , the concave venter bordered by two ridges — is retained. Practically it lasts throughout the ephebic stage, and the engonoceran stage is passed through with great rapidity. In this the venter is flat and bordered by well-defined elongated tubercles, and consequently there is a quick appearance of the senile stage with elevated convex venter between large elongated nodes. It should be noticed that one of the varieties imitates the sutures of E. suhjertion in the shape of the saddles and lobes, but these remain characteristically simple in outline (PI. XIX, fig. 11). Some varieties have bifid saddles and some do not have them. The dividing marginals of the saddles enlarge by growth when they occur, until the}- often form lobes practicalh' inseparable from others. Local itij: Four and one-half miles northeast of Gaines^alle and Denison, Tex. A(/e: Upper part of Comanche series. Paw Paw beds, Washita group. ENGONOCERATID^E. 165 Engonoceras pierdenale (von Buch). PI. XX, tigs. 6-13. AmmonUesj^lcrdemdls von Buch, Ahhaiidl. K. Akad. Wiss. zu Berlin, 1848, pi. H, tigs. 8-10. AMimm/'tex Dedcrnalis Roenier. 1852, Kreideb. v. Texas, PI. I. tig. 3. Engonocerax 2»^dei",aU>< Bohm. ISKS. Zeitsclir. Deutsch. geol. Gesell., Vol. L, p. 183. I have placed this here with n query, because I find it impracticable to identify tlie young- figured by von Buch with any form known to me. The ventral lobe and saddle and the otlier parts of tlie suture might belong to the young of a species a grade more complicated than any here described. There is a row of elongated nodes close to the venter in von Buch's figure, but the presence of such ornaments is denied in the text, and the nodes are said to be on one side and due to the exposure of the joints of the siphuncle. Roemer states that he had the originals in linud when making his descrip- tion, and that the species was nuu-li larger than that described by him. Neumayr mentioned this species as the type of his genus Eiif/onoceras" and repeats the name "pierdenalis" instead of "pedernalis," the name given by Roemer, and also repeats von Buch's figure of the suture on PI. 7 ot tJber Ceratiten. Von Buch and Neumayr also both describe the principal saddles as bifid, a condition that does not exist in any specimen (if the genus that I have seen. Localitij: Texas. Age: Fredericksburg group of Comanche series. Engonocekas pierdenale variety commune Hyatt. PI. XXI. tig. 1. A fragment in U. 8. National Museum, No. 8301b, from Bell County, Tex., is slightly crushed in the umbilical region, but has sutures and mark- ino-s well preserved. At larger end the volution is 33 by 14 mm., at smaller end 24 by 1 1 nun. The venter is flattened and narrow, bordered by small elongated tubercles rather numerous and closely set as in the adults of this species. There is an inner row of tubercles, hardly perceptible median row, and equally faint fold-like costations on the outer part of the volution, which can be felt better than seen on this cast. "Amm. d. Hilsbild. Xorddeutschlands, Palwontogr., Vol. XXVIl, 1S80-81, pp. 188, 141. 166 PSEUDOCEKATITES OF THE CRETACEOUS. The ventral lobe is slightly asj'mmetrical to the left, g-iviiig- ri«e to considerable diflferences in the first lateral saddles on either side. The first lateral on the rio-lit is l)ifid, the outer arm very broad and Ijifid, the inner subdivided asymmetrically by a very minute mai-ginal lobe. Be}'ond this the inner arm is entire and quite large and iihylliform. There are ten saddles and nine lobes on this side All tlu- former are entire except the innermost, which is slightly bifid The lobes vary from trifid to six-poiuted. On the left side the first lateral saddles have the usual bifid form without further subdivisions. All the saddles appear to have entire phylliform out- lines, but this may be due to the worn sutures. The first to fourth lobes are slightly digitated, the fifth is faintly trifid, and beyond they are too much worn to show the minute serrations. On the left side the first lateral saddles have the usual bifid form, the outer arm broad, pointed externally, and with only a slight indentation on the maro-in. The second to seventh lateral saddles are entire and phylli- form; the eighth is broad and deepl}- bifid, but is apparently only one saddle; the ninth and tenth are entire. The first to fourth lobes are faintly denticulated, the fifth and sixth narrow and trifid. The seventh is totally unlike any other lobe. It seems to be filed by a pointed saddle, the end bifid in one case. There is also another specimen from the same locality, a cast with a part of a living chamber preserved. This is about one-half of a volution and in tlie gerontic stage, the last five sutures overlapping. The preceding sixth or eighth, being in the ephebic stage, do not overlap. The lobes and saddles are like those of the fragment just described, the sixth to the eighth saddle on the right side being bifid and the ninth entire. The saddles iu old ao-e, however, are flatter and the lobes become shorter. The ornaments are the same as in other specniiens, but the venter becomes broader in proportion to age; tubercles persistent. The living chamber is obviously nearly complete and must have been at least one-half of a volution iu length. Three small fragments from locality No. 1554, Seven Knobs, near Glenrose, Tex., have tubercles larger and more prominent, and although the sutures vary the} are near enough to belong to the same species. The laro-est specimen over one- half of a volution is 52 mm. in diameter. Probably, allowing for compression, this diameter is only 45 nun. The ENGONOCERATID^. 167 living chamber is about one-half of a Nolution and is nearly complete. The venter broadens ont, and this specimen seems to be outgrown, judging from the approximation of the last three septa. The sutures are similar to those of the preceding, but the seventh saddles are bifid. Specimen from locality 1.^45, Chalk Mountain, near Glenrose, diameter of ^ olution 50 nmi., partly estimated, has seventh saddle on the right side bifid; all others external to this entire and phylliform, except, of course, first lateral. This cast shows plainly that what is here counted as the second lateral is an adventitious .saddle derived from division of the first lateral saddles, and the first lateral lobe is also an adventitious inflection arising from a ]irimitive marginal of the first lateral saddle. A fragment from the Cxoodland limestone, Choctaw Nation, al>out lOO miles east of Preston, Tex., is consideral)ly worn, but apparently of this species. The volution is 33 mm. fmm line of involution to venter and is in gerontic stage, the last six sutures overlapping. The venter is also rapidly broadening, the gerontic tubercles and costte are larger than usual, and the venter is more asymmetrical or zigzag in outline. There are nine saddles visible, and the seventh and eighth are bifid; the outlines of others are entire. The lobes, owing probably to attrition, are all entire. A specimen in the United States National Museum, No. 22643, from locality No. !)73, near Cerrogordo, Ark., has a combination of characters which appears to unite serpentinum with i^ierdenale . The sutures have the broad, short saddles with flat bases, like those of serpentinum from near Gainesville, but the size of specimen, nodes, and aspect are similar to the typical fossils of pierdenale. The surface is worn down somewhat in this cast, and probably these resemblances may. be due to this cause. This cast is 91 mm. in whole diameter; transverse diameter estimated at 20 mm A cast in the Museum of Comparative Zoology from Towash, Hill County, Tex., is 56 mm. in diameter; the outer volution is 27 mm., the umbdicus 8 mm., and the opposite part of same volution from line of involution to venter 21 mm. This is an outgrown specimen, the last six sutures overlapping those preceding, while in e])hebic stage they are separated by a distinct interval. There are the usual lines of tubercles, and the costse on the outer jjart ( if the volution become very decided, as in other aged specimens. The venter is at first narrow, but this becomes much broader at the same time that costaj 168 PSELTDOCERATITES OF THE CRETACEOUS. increase in .size in lust })Hrt of tlie outer volution The venter runs from 2 to 7 mm. in width on this one volution. The living chamber is complete hiternallv and is somewhat less than one-half of a volution in leno-th. The sutures resemble those of specimens described above except that there are only seven saddles, the fifth and sixth very broad and bifid, the seventh entire. The first to third lobes are very slightly digitated; the rest are entire. Bohm's studies of the originals of tlie descriptions of this species have been referred to in the generic description. Whatever doubts of Bohm's con- clusions may remain in the mind, it is surely safer to follow such an investi- gator, who has worked over the original materials, than to indulge in speculations with regard to the exact meaning' of von Buch's and Roemer's descriptions and figures, about which the most opposite opinions might be reasonably entertained. Engon'ocer.^s subjectum n. sp. Hyatt. PI. XXI. tio-s. 2-6; PI. XXII, tigs. 1-.5. A good cast of tins form (No. 431 in Museum of Comparative Zoology) is 101 mm. in diameter, the inner oldest part of the outer voh;tion being partially destroyed, so that this could not be measured. The living cliamber was probably, when perfect, not less than one-lialf of a volutiou in length. The whole diameter was about 102 nmi.; the transverse diameter was decreased so by compression that the measurement near base of living chamber could not be relied on, but this was 18 mm., the ventro-dorsal breadth of side being at the same place 43 mm. The living chamber having been excavated, it was possible to measure the interior volution in the same line with the largest diameter given above. This was found to be 73 mm., the largest volution being 40 nmi., the umbilicus 7 nnn., the opposite part of same volution 26 mm. No shell was present on this cast. The involution covers up the entire side of inner volution at diameter of .S6 mm. This is found in several specimens, but does not apjiear to be invariable. There are large nodes along the umbilical shoulders, very ol)scure nodose folds along the central surfaces of lateral zones, and prominent elongated alternating nodes along either border of the venter. These last are finer in the ephebic stage than in the gerontic substages At dianieter approaching 100 nmi. the venter loses the flattened aspect ot ENGONOCERATID.E. 169 the ephebic stage, becomes broader and slightl}' rounded, but still retains the tubercles and asymmetrical aspect due to their prominence and alter- nation. The g-erontic living chamber is about one-half of a vohxtion in length on tlie ventral side, the dorsal side being absent. The earliest suture in type No. 431 at diameter of 2(i nun. from line of involution to venter has eight saddles and seven lobes to the umbilical shoulders. Beyond tliis they were not visible. The saddles are narrow and phylliform or club shaped; the lobes also are clubbed and have primi- tive denticulations. First lateral saddle is trifid and inner mai-g-inal lobe is digitated, the second to fourth entire, fifth to eightli l:)ifid. The ventral lobe is longer than usual in this o-enus, but has the usual form, divided bv entire broad siphonal saddle. The iirst, second, and third laterals have about live denticulations unequally divided, and the fourth is trifid. Later in the gerontic stage the .second to fourth saddles become either bifid or have more digitations, and the digitations of the lobes increase to seven; the phylliform aspect also increases. When the volution is about 37 nnn. in diameter from line of involution to venter, there are apparently about the same number of saddles and lobes, PI. XXI, fig. 5. Tlie lobes have more denticulations and the third saddles are also faintly bifid. In ;mother specimen, PI. XXI, fig. 6, same locality at about the same age, all the saddles and lobes are shorter and broader in proportion, but decidedly phylliform, the lobes are more denticu- lated, the first lateral saddles deeply trifid, the second to fifth saddles entire, the sixth to the eighth (the last one visible) distinctly bifid. A cast (No. 10755, Boston Society of Natural History) from Bell County, Tex., is 75 mm. in whole diameter. The entire volution is 39 mm. from venter to line of involution; the umbilicus is 10 mm.; the diameter oppo- .site from line of involution to venter is 27 mm. This is in the gerontic stage, the last five sutures overlapping. There are ten saddles and nine lobes on the left side. The second to the sixth are entire, the seventh to the ninth are bifid, and the tenth is entire. The saddles and lobes have the elongated phylliform character of this species. Locality: Gabriel, Williamson County, Tex. Afje: Comanche series, Wa.shita? The remarkable and highly instructive specimen described below is a cast with an appro.ximate diameter of 55 mm. It was received from Dr. 170 PSF.UDOCERATITES OF THE CRETACEOUS. 1). S. Martin and came from Grayson, Tex. Tlie sntures on the right side possess a decidedh' unique aspect, having- a first lateral saddle entirely different from that of any specimen of this genus 1 have yet studied or seen fio-ured. The whole aspect of these sutures indicates a new species, whereas the sutures on the other side, although considerably abraded, are perfect enough in places to show the ordinary form of first lateral saudle conunonly ■found in Metengonoceras. The sutures of the right side are more like those oi' E. subjectum than those oi E. pkrdenah, but the}- are quite distinct from l)oth in the aspects of the saddles. On the right side there are nine saddles and eiffht lobes. The first lateral saddle is broad and distinctlv trifid. The inner arm is broad and has the usual shape of other species, being pointed externally and running well on to the venter. The central arm is a narrow, small marginal saddle between two small entire marginal lobes; the inner arm is narrower than the outer arm and phylliform. The second to the fourth saddle are entire and phylliform, the fifth and remaining saddles have flatter bases. The fifth is still entire and the remaining saddles also, except the sixth, which is broad and bifid. This bifid character can be detected only on the first part of the outer volution where the dividing lobes are not abraded, but even this is open to some doubt. The ventral lobe has the usual outline and is symmetrical in position; nevertheless the first lateral saddles on the left side are quite distinct from those on the right side. They have the usual bifid character of specimens of other species, and there is nothing unusual in the outlines of the sutures on this side. The seventh and eighth saddles are bifid, and the sixth is entire. The ninth saddle is broader than on the right side. The condition of the sutures on this side did not admit of more minute observations. The first to the fourth lobes on the right side were of the usual form, but rather coarsely serrated and similar to those of specimens from Bell County, Tex., described above (collection of the Boston Society of Natural History, No. l(/755). It agreeil also with the last in the prominence of the middle line of tubercles. Locality: Grayson, Tex. Similar sutures occur in a cast of this .species kindh" loaned me l^y Prof F. W. Cragin, and in this the eighth saddles are on the umbilical shoulders and the broad ninth reaches to the line of involution: the second to the sixth saddles are entire; the seventh to the ninth are bilid. Locality: Tarrant County, Tex. ENGONOCERATID.E. 1 7 1 The venter in this species remains concave and has a sharp ridge on either side at the ventro-hiteral angles, broken into waves by equally acute but elongated . nodes on the casts. Shells were not present. In old age these nodes persist, but the ridges disappear and the venter becomes flat- tened, and tinallv convex. A cast from Denison, Tex , Duck Creek beds, United States Geolog- ical Survey, has verv different sutures and is also somewhat difl^erent in general aspect. The living chamber is complete in the inner borders and is considerably less than one-fourth of a volution in length. It is in the gerontic stage; the inner tubercles are large, and the outer ones, terminating short, fold-like costa;, are also very large. The venter is completely rounded and mucli zig'zaga'ed in correlation with the larue tuberculoae alternating: folds and nodes o\' the eosta?. The whole diameter is 92 mm.; the outer volution, which is somewhat reduced by gerontic contraction, is 42 mm.; the umbilicus is 14 mm., tliis being enlarged in proportion to reduction of gerontic i)art of volution, and opposite from line of involution to venter is 36 mm. The saddles are quite distinct from those of specimens described above, but have the same distinctly phylliform aspect ; the lobes are more alike and with similar serrations. There are nine saddles on the right side. The first lateral has the same deeply bifid form as in specimens of this species. The second to seventh have rounded leaf-like bases; the eighth is still phylliform, but broadens out and is bifid; the ninth is entire. The fir.st lateral lobe is evidently very sligiitly divided, but the second to the fifth are more richly denticulated than the sixth and seventh and are faintly trifid ('?); the eighth is perhaps entire, but not plainly seen. The living chamber is shorter in this specimen than in any other example of this species and the nodes are more like those of ser- pentimivi, while the sutures agree better with those of subjeetituL The principal distinction lietween this species and its allies of the same genus lies in the more elongated phylliform saddles and lobes. Engonoceras gibbosum n. sp. Hyatt. PI. XXII, fig.s. H-10; PI. XXIII, tigs. 1-6. The best example of this sjjecies is an entire cast in my collection from Cook County, Tex. This has the median line of nodes along the centnd line of the lateral surface, the outer distinct and short and no ])erceptible 172 PSEUDOCEKATITES OF THE CRETACEOUS. costse between these. This cast, tlie type of tlie species, shows no gerontic characters at the diameter of 93.5 mm. The greatest transverse diameter is at tlie nmbihcal shoulders and is 25 mm., the breadth of tlie side at the same point being 50 mm. The sutures are quite different fi-om those speci- mens described below, l)ut there is the same general character: the second lateral saddle and the fifth ai-e bifid; the sixth is unequally trifid; the seventh is a compound saddle with two bifid arms; the eighth to the tenth are entire or flat. The more gibbous sides, the prolonged stage during which the nodes persist and are sharply defined, and the large number of bifid saddles characterize this species. The sutures are the most complex, with exception of Eng. roeiiieri, of any that have been so far descibed in the genus. The largest fragment in the National Museum is about three-eighths of a volution. Widest diameter is 9 1 mm. ; the distance from line of invo- lution to venter is 50 nnn. at the larger end and 38 mm. at the smaller end; and the transverse diameters are 20 mm. and IG mm., respectively. This specimen was probably entirely uncompressed. The venter is naiTow and flat and the sides are slightly gibbous and highly convei-gent outside of the middle row of obscure nodes. Between these and the umbilical shoulders, however, a flattened zone is developed, which may even slightly slope inward The usual row of nodes is present on the umbilical shoulders, and also the rows of alternating tubercles on each side of the venter. The latter are sharj) and well formed, elongated, and sufficiently numerous to give a decidedly zig-zag aspect to the narrow venter. The venter is flat in the early part of the neanie stage and much broader in proportion to the volution than in later stages, as it is in most species of this genus. The volution has more flattened sides at this age, and the involution begins to cover up the volutions to the umbilical shoulders even at this early stage. The sutures are well separated, as in other shells of this genus, and are very remarkable. There are on the right side ten lateral lobes and eleven saddles at the larger end of this fragment and the same number at the smaller end. These are more difficult to count and quite different on the left side. The ventral lobe is synunetrical and of the typical form. On the right side the first lat<'ral saddle is bifid, the outer arm short, broad, and spreading, the inner also broader than in most other forms; ihe outer is .subdivided by a minute marginal or slightlv and unequally ENGONOCERATID.E. 173 bifid; the inner arm is sliglitly trifid in nearly all the sutures, and this becomes more apparent in the older sutures. The lateral saddles are broadly phyllitbrm. The second laterals are obscurely and equally l:)ifid in all the sutures: the third shows a faint tendency to become bifid only in the older sutures; the fourth seems to have a similar tendency, but this does not become demonstrable, and it must he described as narrower at the base and entire. The fifth is bifid in the younger sutures observed, and becomes more distinctly bifid with age; the sixth is narrower and entire; the seventh is equally bifid; the eighth is also equally bifid, but the inner ai'm is unequally subdivided by a minute niarginal; the ninth is also equally bifid, and each arm is also bifid with a minute marginal lobe; in some sutures both are unequally divided and in others the outer is symmetrical, the inner asA'mmetrical; the tenth is small and entire, and the eleventh is very broad and is subdivided by a minute marginal lobe introduced on this volution, and the outer arm shows a tendency to bi'oaden and become bifid in the older parts of the same. The saddles are phylliforin but rather sliort and stumpy from second to sixth, then they become very broad and less phylli- form; the lobes have the usual narrow bases between the expanded bases of the saddles and spread out apicad between the phylliform saddles. These are all apparently unequally subdivided, and the digitations and serrations are somewhat more numerous in the second to the fifth laterals than in most other species. The fir.st and sixth are simply trifid, the seventh and eighth bifid, the ninth and tenth entire. On the left side the first lateral saddles have a narrower outer arm, divided by a deeper marginal lobe, and the inner arm is not so broad and shows only a faint tendency to become bifid. The second lateral is more distinctl}- but unequally bifid; the third shows a faint tendency to a trifid luidulation; the fourth is entire; the fifth is faintly bifid; the sixth is dis- tinctly but asynnnetrically bifid; the seventh is equally and deeply bifid; the eighth is very liroad and also deeply bifid, the outer arm has the margin faintly undulated into four nearly equal marginal serrations, the inner arm is asynnnetrically bifid; the ninth is also unsymmetricallv divided, the outer jjart or arm is ver}' broad, rather rounded basally and undulated into three minute serrations on the margin, the inner arm is a minute saddle; the tenth saddle is like that of the right side, but faintly bifid in the first sutures seen; the eleventh saddle is narrower than on the right side and 1 74 PSEUD0CERAT1TE6 OF THE CRETACEOUS. entire. The lobes are all shorter, with broader ends apically and with less complex digitations than on the right side. One small .specimen, a cast from locality 14!i2, 15 miles west of Denison, Tex., has a diameter of 46 mm., outer part of volution, 23 mm.; transverse diameter, 11 mm.; umbilicus, 7 mm.; and opposite diameter from line of involution to venter, 16 mm.; transverse diameter, 7.5 mm. This has the same shape of venter and general aspect. The nodes of the inner line are present as elongated costje, which are most prominent at the umbilical shoulders and much inclined orad. Very obscure nodes could be felt over the more perfect surface of the cast along the centran lateral area. The cast was too imperfect along the venter to observe nodes, but at the beffinuinff of this volution on a small bit of the shell of tlie venter exposed by excavation there were smooth ridges at the ventro-lateral angles, and the venter was concave. The sutures in this are crowded together luiusually close for shells of this genus, the inner lobes and saddles overlapping slightly, beginning with the third lobes and fourth saddl&s. It is probably a dwarfed form of tliis species, since in the earlier part of same vojution the sutures are well sepa- rated, as in other forms. The ventral lobes are obliterated, but sufficient of the first lateral saddles remain to show that they were unequally bifid and that the outer arm was also bifid, the inner arm entire and quite large. The second to fourth saddles on the left side were broad and entire, the fifth to seventh symmetricallv and deeply bifid, the eightli very broad and unequally bifid, the outer arm faintly bifid, tlie ninth alone entire. There is considerable variation on the right side, the sixth saddle is not deeply bifid, the seventh is unequally bifid, the eighth is like that of the left side, but the bifidity of the margin of the outer arm is more pronounced. Tlie ventral lobe is symmetrical, but so much worn down that no observations were practicable except at two of the sutures, when it seemed to have the usual generic form. Tlie living chamber was not present in either of the above- described specimens. A small cast from Bell County, Tex., No. 8301a, about a fourth of a volution, is 23 mm. in diameter from line of involution to venter, transverse diameter 14 mm., two lines of tubercles and median line of elevations well defined, venter distinctly concave. The sutures appear to have more ENGONOCEKATID.E. 175 resemblances to those of the older stages of this species than to an}' others. The ventral lobe is narrow and slightly asymmetrical to the left, but the first lateral saddles on both sides are alike. They are both bifid, the outer arm is entire but is blunter tiian usual on the venter. The first to sixth saddles are otherwise like those of the specimen described above; the sev- enth to ninth saddles, seen only on the left side, are symmetrically bifid, the tenth is entire. This bifidit}' of the internal saddles agrees with those of uddeni, but the aspect of the volution and the general form of the saddles and lobes agree better with those of this species. Locality: Cook County, Tex., 15 miles southwest of Gainesville and 15 miles west of Denison. Age: Fredericksburg division of Comanche series. Engonoceras stolleyi Bohm. PI. XXIII, tigs. 7-9; PI. XXIV. tigs. 1-.5. Enf/onoceras stolleyi Bohm, 1898. Zeitschr. Deutsch. geol. Gesell., Vol. L, pi. 5. This species has the flattened venter, becoming alternately nodose and zigzag in old age, as is characteristic of this genus. It is not distinguish- able from E. pierdenale except in the sutures. The lateral saddles and lobes are smaller than in any other species of this genus, and the first lateral saddles are apt to have the inner marginal saddles tongue-shaped. This peculiarity is noticeable in Bohm's figure and in the large fossil (PI. XXIV, fig. 5). Aye: Fredericksburg group [?], Comanche series. Lower Cretaceous. Engonoceras complicatum n. sp. Hyatt. PI. XXIV, tigs. 6-8. This is founded upon a cast from near Austin, Tex. The whole diameter, i)artly estimated, is 73 mm., the' outer volution is 39 mm., the umbilicus 9 nun., the volution opposite (estimated) 25 mm. By the cast alone this species could not be separated from Enyonoceras yihhosum, but the sutures are nevertheless entirely different. A better preserved sjieciinen might, however, show some external characteristic distinctions. There are fourteen sutures visible on the outer volution; then comes a gap between 176 PSEUDOCERATITES OF THE CRETACEOUS. them and those on the first quarter of the same volution. The entire fourteen overlap, but the tenth, eleventh, and twelfth are nearer together than any others. The ephel)ic sutures on the first quarter of this same volution are well separated. There are eleven slender saddles and ten slender lobes on the left side. The first lateral is narrower tlian in any other species and bifid, with tongue-shaped entire arms; the second and third laterals are also entire and linguiform; the fourtli to the ninth are l)hylliform and bifid; the tenth could not be seen; the eleventh was entire. The ventral lobe is narrower, deeper in proportion than in other species. There is a smaller and contorted cast from Benbrook, Tex., with similar sutures so far as the bifidity of some of the ])rincipal saddles is concerned. It is very likely a variety of this species. The markings, so far as can be determined, are similar. The living chamber is alx)ut one-half of a volution, the last sutures overlap, and the shell was evidently in the gerontic stage. The thu-d latei-al saddles were bifid, the fourth was entire, the fifth to ninth were more or less phylliform and bifid, and beyond this none were visible. It differs from Protengonoceras emarginatum (Cragin) in having pi'O- nounced lines of tubercles along the veutro-lateral angles and its greater number of lobes and saddles, judging from the descriptions of that species. The characteristics of the venter and the size as given by him indicate a larger species, with venter more like that of Proten. gabbi, A small specimen, a cast, from 15 miles west of Denison, Tex., iias a diameter of 4G mm.; outer part of volution is 23 mm.; transverse diameter, 1 1 mm.; umbilicus, 7 nun., and opposite diameter from line of involution to venter, IG mm.; transverse diameter, 7.5 mm. This has same shape of venter and general aspect. The nodes of the inner line are present as elongated costse, most prominent at the umbilical shoulders and much inclined orad. These disappear as they pass the centran lateral surface. Nodes could not be seen nor felt over the perfect surface of the cast, and none were visible at the beginning of this volution on a small bit of the shell of the venter exposed by excavation. The suture.s in this specimen are crowded together unusually close for shells of this genus, the inner loljes and saddles overlapping slightly, be<'-innin«'- with the third lobes and fourth saddles. It is probably a ENGONOCERATID.li;. 177 dwarfed form of tins species, since in the earlier parts of same volntion the sntures are well separated, as in other forms. The ventral lobes are obliterated, but sufficient of the lirst lateral saddles remain to show that the)' were equally bifid and that the outer arm was also bifid the inner arm entire and quite large. The second to fourth saddles were, on the left side, liroad and entire, the fifth to seventh symmetrically and deeply bifid. Locality: Near Austin and Benbrook, Tex. Age: Fredericksburg- group, Comanche series. Engonoceras emarginatum (Cragin)." Sphetwdisciis e7narginatv« Cragin, 1893, Geol. Surv. Texas. Fourth Ann. Rept., p. 245. According to Cragin's description, this species has the concave venter until M late stage, lint has the tubercles and sutures of this genus. Engonoceras roemeri (Cragin). Sjyhenodiscnx roemeri Cragin, 1893. Cieol. Surv. Texas. Fourth Ann. Rept., pi. -46, Cragin describes this shell as having "venter narrowly truncate, the ventro-lateral angle at first sharp, becoming on the body-chamber subtu- berculate-siuuous." This and the general outlines of the sutures, if they are supposed to be deprived of their marginal saddles, as they must have been in the young of this shell before these were developed, has caused me to refer the species provisionally to this genus The sutures are, however, obviously more complex as figured by Cragin than in any other known form of Enfionoceras. The principal saddles are all bifid, trifid, or ([uadrifid, and the smaller saddles inside of Avliat appears to be the fourth saddles are mostly bifid. Mr. Stanton has writteli as follows regarding this form: According to Cragin, this is from the "alternating bed.s" — that is, the Trinity division — not Fredericksburg, as given in your MS. If this be true (and Mr. Taff's stratigraphic data look all right), the form is pro))ably the oldest one of thi.s group that we have from the Comanche series. Locality: Iredell, Bosque County, Tex. Age: Comanche series, Glenrose beds. " See p. 157, where this species is doubtfully referred to Protengonoceras. — T. W. S. MON XLIV — 03 12 1 78 PSEUDOCERATITES OF THE CRETACEOUS. NEOLOBITES Fischer. The sutures of this geuus have, perliaps, simpler outhiies than those of anv other Cretaceous ammonoid, and have been supposed to phice the genus somewhere near Tissotia. They, however, differ decisively fmm those of an}' of this "roup in having- long phylliforin saddles and a very peculiar ventral lobe. The form, ornamentation, and old age of the species from Tunisia, described by Peron, would place it in the genus Placcnticeras, if no sutures were visible. But the sutures and ornamentation agree with those of Engonoceras, and sho\\' that it is probably a member of the same family. Choffat's researches have placed this conclusion on a secure footing. His Neolohites inbrayeanus may not be identical with d'( )rbign}''s species, l)ut it is surely a close ally, and he gives the sutures in full, and these show the \entral lobes and siphonal saddles and first laterals to be similar to_those of Engonoceras. If the young, when seen, prove to have a similar development, the evidence will be complete. Neolobites vibrayeanus (d'Orbigny). Ainmonitcs vihrayeanii>< d'Orbigny, 1840, Terr. Cret., pi. 90, iigs. 1-3. J^.olohites vthrayenuits Choffat, 1898, Faune Cret. du Portugal, Vol. I, 2d series, pi. 5, figs. 2, .5 (not Iigs. 3,4.) This species as figured by d'Orbigny has led to great confusion, owing perhaps to the absence of a sufficient representation of the details. Choffat has figured a species from Portugal which, if not identical, is })robably similar to d'Orbigny's species. All the characters coincide with the posi- tion here given to this form. A number of species are confused under this name, but the data given are not sufficient to separate them. Locality: France and Portugal. Age: Cenomanian. Neolobites choffati n. sj). Hyatt. PL XXV, Iigs. 1-t. Weoldbitef I'ihntij.'dnns Choffat, 1898, Faune Cret. du Portugal, Vol. I, :.'d series, 1)1. .5, figs. 3,4 (not figs. 2, 5.) This is obviously distinct from inbrayeanus, as is shown by the broad venter and distinct sutures as well as the more gibbous form. Locality: Portugal. Age: Cenomanian. ENGONOCERATID.E. 179 Neolobites peroni n. sp. Hyatt. Neolobites vlhrnt/eauH-y Peron. 1S!)0. ^loll. Cret. de la Tuiiisie, pi. IM. tigs. 1. 3. A highly compvesscd shell with navrow flat venter bordered on either side by a line of small, closely set tubercles with luimerous costse on the flat sides, focussed into a very few large nodes near the umbihcal shoulder. The involution is almost if not quite complete. Tlie umbilicus is not flgured in Peron's flgure, but it must have lieen very small. In extreme aare these nodes recede farther from their flrst iiosition, the ventro-lateral lines of small tubercles disappear and the venter becomes elevated and is represented in the last stage as subacute. There are five or six lateral saddles in this species, according to Peron's drawing. Peron considered this form to be distinct, but did not describe it as a new species. Locality: North Africa. Age: Cenomanian. METENGONOCERAS n. gen. Hyatt. The shell is compressed as in Emionoceras and the involution covers the greater part of the sides of the internal volutions. Broad, fold-like sigmoidal cost;* are present in some species and faint tubercles have been observed in rare cases on casts. No well-preserved shells have been so far seen nor described The venter in the neanic stage is comparatively broad and slightly concave; in the ephebic stage it becomes very narrow, but retains a linear concavity; in the full ephebic stage it becomes acute, and in o-erontic stag-e subacute and then rounded. The sutures do not differ materially from those of Emjonoccras ; the distinction, so far as known, lies in the development of the venter and absence of nodes. The young were similar to the adults of Frotengonoceras, as are those of other genera. The principal or outer lateral lobes and saddles are short, the lobes narrow and entire between the entire and more or less rounded, often phylliform l)ases of the principal saddles. The apical ends of the lobes are denticulated, but the marginals are entire, pointed, and the saddles blunter but also entire. The smaller inside of the jjrincipal outer saddles are often bifid. The ventral lobe is narrow orally, very short and broad a|)ically, with two entire arms, and is divided by a depi'essed but more or less subacute entire siphonal saddle. The first lateral saddles in most species are broad and 180 PSEUDOCERATITES OF THE CRETACEOUS. bifid, the outer arms more or less acute at the outer aug'les of the bases, and the inner arm narrower and tong-ue- like. One of the marked characters of this g-enus is the absence of differentiation between the parts of the suture at later stages of growth. The princi{)al lateral saddles and lobes can not in many specimens be distinguished from the so-called auxiliary laterals, and I have not attempted to do this in my descriptions. In some specimens, on the other hand, especially young ones, there seem to be plainl}^ only three principal lateral saddles or lolies, but in others there seem to l)e four or even five. The metaneanic substage in one species showed the primary division of the primitive first lateral saddle into three, and in several specimens in a late neanic substage it seemed obvious that this subdivision was maintained and that the first lateral of the derivative or principal series became bifid late in the life of the shell. First lateral saddles are therefore morphologically double, even when they are so fully divided that the}' have to be considered as two saddles, as in Metenyonoceras dumhli. In most species there is no difficulty in seeing this, but in about all of them the line between the three principal laterals and the auxiliaries can not be drawn, nor between the principal lobes and the auxiliaries. Here, however, as in Engonoceras, there are but three principal laterals, if the first lateral is properly defined as double or bifid. The subacute venters of the species in this genus have lead to confusion with Sphenodiscus and its allies. The ontogeny of the latter separates the two generically, but the latter might be considered an accelerated form of the same family, as stated above in the description of the famih-, but for the sutural characters which show that Sphenodiscus belongs in the Placenticeran stock. Metengonoceras inscriptum n. sp. Hyatt. PI. XXV, tigs. o-;t: PI. XXVI, Hgs. 1-4. One entire cast is 80 mm. in diameter. The diameter from line of involution to venter is 42 nun. at largest part, the transverse being Hi mm. Both measurements are a trifle short of what they would be in a more pei-fect cast. Opposite this the same diameter is 29 mm. without shell, the umbilicus being 9 mm. A fragment somewhat vounger from same locality was not compressed so as to destroy the shape. This had the same form, but was not so con- cave near the iimbilicus and had no folds. The volutions were flat on the ENGONOCERATID.E. 181 venter in the n^anie stage, and were ()l)vi()usly siinilar to Protengonoceras in their young. The smaller Iragmeut, nearly one-half of a volution, with center partly preserved, is 52 mm. in diameter, and the venter is worn, Ijut in places where sutures are perfect the venter is narrowly rounded. In the largest cast, at about the same age, I was able to demonstrate hv excava- tion thnt the shell, although very narrow, was thick and distinct!}' concave on the venter. There were apparently no large tubercles at an}- stage. The first lateral .saddles in the small fragment, at a diameter of over 52 mm., were broad, very short, and had the inner angle furnished with a large marginal lobe and saddle. The second to fifth saddles on tlie right side, and the second to sixth on the left side, are entire, the sixth on the right and seventh on the left being the first of the bifid saddles. The other saddles are all bifid, except, perhaps, the innermost pair, but this was not seen. The lobes are too much worn down to show their minute d'Vitations except in a general way. The ventral lobe and minute median saddle are present and the first lateral saddles are narrow. On the youngest and least-worn part of the larger specimen on the right side, the first lateral saddles show .slight marginal lobes and saddles at each of the inner angles, but there are minute marginal lobes on the outer parts of these saddles. Several of them show this division, and one is distinctly trifid. On the older jjarts of the same specimen tliey are, however, distinctly entire as in the other fragment, and this I think is the normal character. The wearing to whicli it had been exposed caused me at first to count three entire saddles on the left side and four on the older jjarts of the same volution. It is obvious, however, that it is the sixtli saddles that are bifid on both sides. The remaining saddles are bifid to the line of involution. In both of these specimens there are ten saddles and nine lobes, but there was probably in each a lobe on the line of involution. The youngest sutures were about 5 mm. distant, but the last nine lost distance rapidly and were more or less irregular, and in the last four the second lateral saddles overlapped slightly the second lateral lobes. The larger cast has three nnich-worn fragments of the attached valves of an ostrean on the right side, which had evidently been exposed above the calcareous nmd while in the same condition as at present, namely, a distorted fossil cast, and the ostreans grew upon the surface of the cast Itself. That the cast had already suff'ered from attrition and compression 182 PSEUDOCERATITES OF THE CRETACEOrS. was shown l)y the nccurate fittmg of the ostreaii shells into tlie irregularities of the broken and worn surface. A few other lower valves were removed to study the sutures, l)ut in no case could 1 find an}' remnants of the shell of Enffonoceras between the bases of attachment of the lower valves of the ostrean and the surface of the cast. The specimens still left u])on the cast show these facts also. The smaller specimen was nuich smoother and clean. A much-distorted fragment from another locality, 9 miles from Austin on Beecaves road, of what seemed to be the gerontic stage of this species is 85 mm. from line of involution to venter and this is verv near to the actual diameter in a perfect cast. The gi-eatest transverse diameter is 35 mm. and is somewhat greater than in a perfect cast of the same age. This s])ecimen, however, has the sutures well shown on the right side, and the differences, with one exception given below, when compared with the first specimen described, t-an be accounted for as probably due to greater age. The saddles and lobes are all much nearer together, the overlapping begin- ning between the third saddle and second lobe. The curvature was the same as in the smaller specimen. The tenth saddle is the first liifid one and the remainder are bifid and near the umbilicus become very broad. This difference cai\ not be accounted for by supposing that the seventh and eighth saddles have become completely divided liy the advance in development of the marginal lobes, thus adding two saddles to the series, but indicates some oi-iginal variation in this shell. The ventral lobe could not be defined and the condition of the other lobes only enabled an observer to see that they were digitated and near the umbilicus they were too much worn to say even this much. The lengtli- enino- out of the saddles by growth does not decrease the phylliform aspect of the bases and the lobes l^ecome nan-ower and longer without apparently altering much in general outline. Locality: Twelve miles northeast of Decatur, Tex. Age: Fredericksburg group, Comanche series. Lower Cretaceous. Metengonoceras inscriptum var. ? This is a fragment of a volution of a large specimen, showing only a part of one side. It is, however, interesting, for the characteristics of the lobes and saddles given on PI. XXV, fig. 8, show variations in the forms of these. A specimen from west of Walnut Springs, Tex., kindly loaned me . ENGONOCERATID.E. 183 by Professor Cragin, shows the subacute venter. The eighth saddles are bifid in this fragment nnd there are only ten on the riglit side, witli large unequally bifid first laterals as in large fragment described above. Locality: Fifteen miles west of Denison, Tex. Locahty 1492, U. S. Geological Survey. Age : Fredericksburg group of Comanche series. One fragment is 55 mm. from line of involution to venter without the shell. The first lateral saddle is deeply bifid, and, counting this as one, there are only five entire saddles, some of which, probably owing to wear, appear to show a faint tendency to become bifid. The sixth to the ninth saddles are distinctly bifid; the tenth is a very broad saddle with three minute marginal lobes, and the eleventh is another liroad saddle which is entire to the line of involution. On the opposite or right side the broad tenth saddle is divided into two bifid saddles, so that there are obviously twelve on that side. LocaUUj: Cow Greek, Travis County, Tex. N... 19105, U. S. National Museum. Metengonockras ambiguum n. sp. Hyatt. PI. XXVI. tigs. 5-7. One nearly entire cast of this form is 79 nnn. in diameter, the last volution 44 mm. from line of involution to venter, the undjilicus 6 mm., and the opposite part of volution 29 nnn. The greatest transverse diameter through median surface is 17 nnn. and is somewhat less than in a perfect specimen. The sutures have smaller saddles than at the same age in M. inscriptum, are also less distant throughout, become still more approximate in later stages, and are straighter. There are thirty septa in tliis specimen to twenty- four in inscriptum at same diameter. The sixth saddles were bifid on both sides. Fold-like costse along the inner part of the volution are plainly visible and there are small nodes along the ventro-lateral angles, the venter being here famtly sinuous. The venter was much eroded, but in two places it showed a narrowly rounded area and on the end of this volution is subacute. pJxcavation was not very successful and I could only demonstrate that the venter was extremely narrow in the ephebic stage and perhaps not distinct from that of Enr/. inscriptum at the same age. 184 PSEI'DOC'ERATITES OF THE CRETACEOUS. This cast was considerably worn. The right side was free of encrusting ostreans; on the opposite (left) side there were a few, some of which were removed. No shell was found between these and the cast. They had evidently grown upon this cast and not upon a living or dead sliell. Tliis can also be seen by studying the remaining shells, one complete lower valve and part of another. Locality : Nine miles from Austin, Tex., on the Beecaves road. Age: Comanche Peak limestone, Fredericksburg group of Comanche series, Lower Cretaceous. Metengonoceras acutum n. sp. Hyatt. PI. XXVI, lig. 8; PI. XXVII, figs. 1, 2. The type specimen of this species in Boll collection in the Museum of Comparative Zoology is a fragment, bur this shows the whole diameter to have been approximately 100 mm. Tlie outer volution from line of involution to venter is 54 mm , the umbilicus 5 nun., and the same volution opposite nmst have been about 40 to 41 mm. The form is much compressed and involute, with more acute venter than in M. inscriptum. The umbilical shoulders also in this species are more prominent and entire, and short but distinct, broad, fold-like costse are present near the umbilical shoulders, but do not cross them. There are no tubercles on the fragments observed. The marginal lobes of the first lateral saddles on both sides are narrow and divided bv a minute marginal saddle or bifid. The first laterals are unsvnmietrically trifid, the second to the fourth are symmetrical and quad- rifid, the fifth is of the same type but not regularly divided. All of these are very narrow at the bases between the expanded bases of the saddles and spread out apicad into the marginal divisions. The sixth lobe is narrow and bifid, with a small marginal saddle, and the seventh similai-, but witli a lar<>er tongue-like marginal saddle, and the minor lobes on either side of this are also subdivided or bifid. The eighth and ninth are distinctly l)Ut very faintly trifid, and nuich longer than the narrow marginal lobes described above as dividing the broad saddles of this part, which are faintly bifid. The tenth lobe was visible but not distinct enough for description. Both specimens were too much crushed in the central parts to give any accurate data for the description of the younger stages. Nevertheless ENGONOCERATID.E. 185 there are strong indications that the venter became acnte in an early ephebic substage. The matrix of these s))ecimens is a red, apparently calcareous, clay stone, and indicates a distinct formation from that containing the species of Place nticer as cited from the same locality and also in the Boll collection in the Museum of Comparative Zoology. They have remnants of the nacreous layer and one has the shell still left in the umbilicus. The interior is so much crushed together that it is impossible to say that the venter was or was not concave in the internal volutions. Certainly, so far as the cast goes, the outer volution was iniquestionably subacute. Three fragments in Cragln's collection from the Grayson marl, one- half to three-fourths mile southeast of the Union Station, at Denison, Tex., have the phylloidal saddles and long complex lobes of this species and aLso subacute venters. The last volution of one of these fragments reaches ventro-dorsal diameter of 60 mm. while still septate, and has a transverse diameter of 24 mm. The sutures, however, are too much aliraded for efficient observation. The peculiar first lateral saddles of this species, the extremely phylli- form saddles, narrow lobes with spreading and digitate extremities, and straightened sutures, separate this from M. inscriptiim. The larger size of the lobes and saddles enables one, as Avell as the more persistent acuteness of the venter in the gerontic stage, to distinguish it from M. dumhli. Mr. Stanton has written as follows with reference to this fossil: "I think this is certainly from the Upper Cretaceous and probably from the Eagle Ford shales, like the other specimens with the same locality label. Such brownish-red concretions are common in weathered portions of the Eagle Ford shales." Local itij: Elm Fork and West Fork (Horton's mill), Dallas Countv, Tex. Aye: Probably Eagle Ford shales, Colorado group, Upper Cretaceous. Metengonocekas DUMBLi (Cragin.) PI. XXVIl, tigs. 3-14. Sphenodiscv.s dumhli Cragin (pai-s), 189.3, Geol. Surv. Texas, Fourth Ann. Rept., p. 2-t3, pi. U. A superb specimen in collection United States Geological Survey, diameter 94 nun., although in three pieces and with nepionic stage and part 186 PSEUDOCERATITES OF THE CRETACEOUS. of outer volution absL-nt, is otherwise perfect and shows many essential facts with reo-ard to the affinities of this o^enus. The last half of outer volution or oreater part of living chamber is in the gerontic stage. Tliis sliows tliat the living chamber was at least one half of a volution in length. Cragin, who had this cast in hand as part of his materials, describes his specimens as being "verj- sharp in the young [my adult], becoming obtuse along the liody- chamber of adult [my old age] specimens." The well preserved part of the o-erontic venter in this cast is 23 mm. long and for a few millimeters is rounded, with two almost imperceptible ridges on the ventro-lateral angles, then a hollow occurs as if the shell had been injured, and this is continued to the end of the fragment by a very faint channel bordered by faint ridges. The young in the nepionic stage has the usual rounded volution: tlie paraneanic substage was compressed with Hat sides, deep involution, and broad concave venter, with entire, acute ridges on the borders. This stage is, in other words, like the ephebic stage of Protengonoceras, as has been already stated from examination of less perfect specimens. This substage was introduced gradually by the intervention of a metaneanic substage having a helmet-shaped section with a flattened venter and an ananeanic substage with transitional characters between this and the nepionic rounded volution, but not having the flattened zone on the venter. In the anephebic substage the compression and flattening continues to increase, tla- involution remains constant, and a very narrow channel .still persists on the venter. In the full ephebic condition this disappears and the venter becomes acute. In the paraephebic substage the venter is subacute, the sides a trifle more convex, and volution somewhat broader in proportion to the ventro-dorsal diameters, but these changes are slow until in extreme age, the paragerontic substage, when, as stated above, the venter becomes rounded. I have frequently alluded to the reinstatement Ijy degeneration at the end of a cycle or in the adult of characters analogous to those of , younger stages, lu tliis specimen the rounded venter of the paragerontic substage has a faint concavity, and this, after what seems to have been some injury to the edge of the venter, becomes converted, as described above, into a faint channel with ridges on the outer borders. There are no marks of tubercles, nor costse, nor folds at any stage so far as these could be seen. ENGONOCERATID^. 187 The sutures have short broad saddles with narrow lobes, digitated only at the apical ends, and while the saddles remain about the same, the lobes increase somewhat in the number of their digitations and in length with age. They are (juite different on the right and left sides. The siphuucle is eccentric to the right, and ventral lobe follows this organ, but there is no verv marked difference between the first lateral saddles in consequence of this. Oh the right si'le the first lateral has two liranches so deeply divided bv a bifid marginal lobe tliat it is really split into two distinct entire saddles, but these are more widel}' separated than in MeteiKj. acntitm, and are more nearly equal in size and aspect. Counting these as two saddles, there are thirteen saddles — ten narrf)w, entire, and phylliform, and three broad and bifid, the eleventh very deeply bifid, and the twelfth and thirteenth successively less deeply divided. The first and second lobes are bifid, tlie third to sixth l)ifid, but with four to eight digitations; the seventh to tenth simplv bifid; the eleventh and twelfth, especially the eleventh, are divided by longer tongue-shaped saddles. On the left side the differences are as follows: The ninth to eleventh saddles are broad and bifid, the twelfth is broad and entire, the thirteenth is very broad and has a sinuous base, and inside of this a very minute lobe shows that there is a small fourteenth saddle. The eighth to the tenth lobes are simply bifid, the eleventli is unequally l^ifid, but has no long tongue-shaped marginal saddle; the twelfth is entire, and there is an excessively minute marginal thirteenth, as stated above. In the adult staere from the fifth saddles inward on both sides the sutures overlap slightly and the outlines are easily separable, but in the last five sutures this overlapping spreads to the third saddles and lobes and the out- lines are more compressed. This is accompanied by a shortening up of the saddles and lobes and a corresponding return t)f the younger proportions and aspect. In the metaneanic substage the primitive first lateral is divided into three low broad saddles l)y simple indented marginal lobes, and the magno- sellarian saddles are also divided, lint the number of these was not ascer- tained. There were, however, only a few of these. Locality: Four miles east of Whitesboro, Tex. Age: Eagle Ford shales, Colorado group, Upper Cretaceous. 188 PSEUDOCERATITES OF THE CRETACEOUS. PLACENTICERATID^ Hyatt. The vouiig are .similar to the aduhs of Phigouoceratida^, having con- cave A'^enters bordered usually by contimious ridge.s with compressed volu- tiftns, the lateral zones converging outwardly. In later stages of genera the venters are either concave, flat, or rounded, but there is no true keel present, although the venter may become acute in some species at a late stage of growth. The volutions in the earlier stages subsequent to the nepionic are apt to be more or less compi-essed, the venters assuming early the characters described above, any further sharpening of the venter occur- ring in later stages. The principal lateral saddles are, so far as known, bifid in the A^oung and show in most groujis a tendency to become more or less tritid in later stages. The multiplication of inflections of the suture lines increases with the involution of the whorls by growth and they become very numerous in some genera. PLACENTICERAS Meek. The species of this genus could be readily distinguished if it were not for the great range of form in the gerontic stage, which occurs in dwarfed as well as in large sjjecimens, and is continually mistaken for the ephebic stage. The neanic shell is smooth, compressed, with at first a flat and then a concave venter bordered by smooth, entire ridges on the shell ;ind on the casts, l)ut has a stouter volution than later stages. It is, in other words, like the ephebic stage of Protem/o)ioreras in external characters, lint the sutures are of the Placenticeran type. Subsequently the ridges become tubercu- lated, the venter becomes nmch narrower and the sides also tuberculated and the volutions more compressed. These spines, nodes on the casts, are in three rows, but may be completely absent in some shells, as they are also in some old shells. In old age the venter again becomes flattened and smooth, and finally broader and rounded. The species are all coimected so closely by intemnediate forms that distinct lines are difficult to draw between contiguous s])ecies. The compressed and highly involute young show that those species, like J', f/iiadulupce, having depressed volutions with broad venters, are senile forms in the ])hylum, or what I have named phylogerontic. They PLACENT1CERAT1D.E. '189 are not scaphitoid, as stated by Muiiier Chalmas, except in the sense that ScaphUe.^ is an extreme case of the same tendency to reproduce senile char- acters early in the ontogeny and to such an extent that tlie ephebic form becomes more or less influenced by them. The species form a series, there- fore, leadino- ofl" from shells, like P. sipiak in one direction into P. guada- lupe and in the other into wUtfieldl The intermediate modifications connecting this genus with Protengonoceras are probably partly represented by Diplaanocems, but this genus is not a primitive, although it seems to be • a i)hyloneanic form. The solution of the species problem apiiears to lie principally in the development of tubercles and the correlative stoutness of the volutions. Shells having heavy tubercles in three lines usually also have sutural pecul- iarities that enable one to distinguish them. The peculiarities of the gerontic stage are also distinct, as will be noticed in the descriptions. In some spe- cies the neanifc stages are quite distinct in their sutures, although alike in their forms at the same age, and perhaps with more materials the study of these and the development of sutures may give good results. Hie most highly modified form as compared with its own neanic stage is cevt-Am\y guadaliipce, but although the sutures are complicated in outline, they are not so complex as those of whiffieldl, and the modifications ot form are distinctly in a phylogerontic direction. The varieties of each species and the development point to the most prevalent syrtaloid form as presenting more than any other purely progressive characters. This form has moderately compressed involute wlioris, with three lines of nodes, narrow venter, and" steadily complicating sutures. The same variations in the species and in the individual point consequently in one direction toward (fuadalupcB and in another toward whitfieldi. This last is reached through si>ecies like stnntoni and pseiidophicenta, in which the median lines of tubercles become permanently obsolete and the outer and iimer lines l^ecome less prominent and in many specimens of whitfieldi are absent. The interesting fact in this connection is that whitfieldi, which, as compared with its own young, is the least modified of all the forms, has the largest shells, the least affected b)- gerontic degeneration, and at all stages the most complex sutures. These facts also show in a marked way the law of retardation of development. This was joined by Cope with acceleration, but so far as 1 90 PSEUDOCEKATITES OF THE CRETACEOUS. my experience goes they are quite distinct. Retardation occurs in cephalopods in phylogerontic forms. Thus in tliis phylogerontic genus the A^oung is a higlily modified, compressed invohite shell in the neanic stage: the adult in some species Wke ffuadalupfe and the f>uro]3ean depressum m;iy have additional modifications ending with a paragerontic stage also tnbercnlated, but with peculiar broad venter and lateral nodes. In other species, obviously closely connected, like jiseudosijrtale, newberryi, planum, • and European congeners like grossouvrei and milleri, the first appearance of tubercles occurs later in tiie ontogeny and they are present in their full development only in the latest ephebic substage or gerontic stage.. The same law holds also in the series leading from syrtale through intercalare and dantoni to ivhitfieldi. In some forms of syrtale and intercalare the three lines of tubercles appear earfier than in the typical forms of the same species and in placenta. In stantoni and 2)sendo2)lacenta this later appearance 'of tubercles becomes invariable and correlates with the disaiJpearance of the centran line and a tendency to decrease in size of these ornaments on the venter and umbilical shoulders. In whitfieldi this tendency results in the total disappearance of tlie tubercles in a large number of shells, three lines of tubercles being present only in a very few shells and always of very small size, plainly individual reversions. The sutures are simpler in outline and contiiuie persistentlv to hold the syrtaloid outlines, and are easily separaljle, except in extreme age, in all of the guadalupan series, including not only the stouter forms like gitadalupfc, but the highly compressed shells like planum. In tlie series leading up to ivhitfieldi there is a mai'ked gain Ijotli in com|)lexitv of outline and in gei'ontic characters. This is apparent in intercalare and placenta, which stjll retain the three lines of tul)ercles, and is still more })ronounced in stantoni and pseudoplacenta and culminates in wJiitfieldi. In these last the sutures are similar to syrtale only in the neanic stage, and in whitfieldi tliev become more rapidly complex in ontogeny than in other species and overlaj) to such an extent that it becomes more difiicult to separate them throughout the ephebic and gerontic stages. This overlapping is a purely gerontic character, and the species that show it during the ephebic stage are therefore i)hyloge]-ontic and to this extent degenerative in spite of the PLACENTICERATID.E. 191 increase in complication of ontlines of the lobes and saddles and their large size. This phylogerontic character is also accompanied, as stated above, by loss of ornamentation and retention thronghout life of the compress«Ml, involute, smooth volutions of the neanic stage. The living chambers are persistently one-half of a volution in length, whether occurring in depressed or compressed shells or in dwarfs, and the apertures, so far as seen, have a short, l)lunt vdstrum and low, broad lateral, crests. Grossouvre's careful descrijjtions and exceptionally fine figures of the difl^erent forms included under the name of Placentkeras syrtale show that while there exists in France and Gerinany a series closely parallel to that of (/iiadahipce, sancarlosense, newberri/i, pseudosyrtale, and planum in this country, all of the European shells present differences showing that the evolution of the modifications was distinct in France. The gerontic stages show a greater tendency on the part of the imier lines of nodes to grow farther out on the lateral zones and approximate to the venter, and tlie venter not only fiattens out to a plano-convex outline, as in some American species, but also in a subsequent gerontic substage, as in P. grossouvrei and miJIeri, becomes more or less concave. This is due to the increasing size of the tubercles of the median line on the borders of the venter after the disappearance of the ventral lines of earlier stages. Kossmat" sums up the literature of the genus Placentkeras and its allies. The type of the genus Buchkeras is erroneously considered as a species of SchloenbacJua. Schloenhachia is a genus with normal outlines to the sutures, a decisive keel with channels or smooth bands on either side, and more or less sigmoidal, prominent, well-developed costae, the aperture having a long, pointed rostrum correlating with the keeled venter. The development is also very distinct from that of any of the Pseudoceratites of the Cretaceous. In preceding- pag-es, B. hilobatum is joined with other related species, and the differences of the series to which it belongs can be more readily seen. Kossmat's strictures with regard to my own work on this group are just and most of his. objections well founded. His reference to balduri Keyserling, as the probable radical of Placentkeras may be correct. At any rate there are some facts that favor this. The sutures are similar to those of Placentkeras. The young of this species certainly "Siiclinil. Kreidef. : Beitr. Pal. unci Geol. Osterreich-Ungarns iind des Orients, Vol. IX, 189.5, ji. 171. 192. PSErDOCERATITES OF THE CRETACEOUS. I'esembles tluit of some of this oeniis in having a chamieled venter, but it is uuich too invohite and compressed for a primitive tvpe. Tlie keel of halduri is devehiped in tlie center of a broad, concave venter of neanic age, as an obtuse raised area, l)ut finally the entire venter becomes elevated with a subacute carina, like that of Buchiceras A raised nascent keel may be said to appear at a late age in some species of I'Jarmticcras, but the venters in them are A'ery narrow, and no such effect is produced as in halduri. The very narrow channel of the ananeanic stage in this species and the late development of the tubercles produce resemblances to Diplacmoceras, but in this genus the outer lines of tubercles are not on the ridges of the venter as the}' are in halduri. If this species is the ancestor of Diplacmoceras, we have still to account for this and the fact that the nepionic stages in Placenticeras exactly match those of Protengono- ceras and Knemiceras and are never keeled as in Buchiceras and Boemeroce- ras. So far as Keyserling's drawings go, the nepionic form of halduri before the channel appears is like that of Buchiceras and Tissotia serrata. The separation of the genus Placenticeras from the Hoplitidae" demands a few words of explanation. Its association with Hoplites by Douvilk' and Grossouvre depends upon the connection supposed to be shown by the large fii'st lateral saddle of HojjUtes splendens. This saddle, as figured by these two distinguished authorities, has the three large marginal lobes and three saddles which are supposed by them to be homologous with the tln-ee principal laterals of Placenticeras. The author's position is quite distinct from this. If the three marginals of H. splendens, having undoubtedly, as stated by them, great similarity to the principal laterals (first to third) of Placenticeras, are intermediate grada- tions and not a case of parallelism, some similar stage ought to be present in the development of species having three principal laterals. This, so fkr as 1 know, is not the history of the development in any form of this kind. "It is disapiKiinting and much to be regretted that no direct mention is made of Prof. .James Perrin Smith's paper on Tlie Devel(jpment and Phyiogeny of Pldfenticfrui: (Proc. Cal. Acad. Sci., 3d series, (ieol., Vol. I, pp. 181-240), although incidental reference to it is made in connection with the jrtaJe and other American species, all of wliicli have very broad ventral lobes and less prominent siphonal saddles. A very fine suite of this species was collected by Stanton and Vaughan, locality 1467, United States Geological Survey, San Carlos, Presidio County, Tex. The largest specimen is 204 mm. in diameter; a, part of the aperture at the umbilical zone shows on one side and the length of the liv- ing chamber is somewhat less than one-half of a volution. The gerontic stage is present and the involution is considerably decreased along the outer sides of the nodes on their retreat from the umljilicus. The venter becomes broader and rounded on the last part of outer volution. The outer nodes change from round spines to elongated costae, dichotomous with the inner line of nodes that are nearly at the middle of the lateral zones at this ao-e. There are some more compressed specimens that still, however, have very stout volutions and a prolonged stage, during which the venter l^ecomes broadened and occupies the space between the second rows of nodes, the outer ventral rows forming lines on either side of a zone occupying the center of the ventral surface. These features are still like those of typical guadalupcB, but in other cases it is impossible to say whether the specimens belong to typical guadnlup(B or to the next described species. Loccditij: San Carlos, Presidio County, Tex. Age: San Carlos beds, Upper Cretaceous. 200 PSEUDOCERATITES OF THE CRETACEOUS. Placenticeras sancarlosense 11. sp. Hyatt. PI. XXX, %s. 1-3: PI. XXXI, figs. 1, 2. This is repi'esented by a senes of specimens in collections made by Stanton and Vaughan that fade into trne guadalupce. The typical forms differ in liaving smaller tubercles, the compressed stage is more prolonged and the ephebic volutions are never so stout nor the venter so broad as in f/itndalup(e. The stage in which the venter is broad and bounded by the second line of nodes and similar to that of (juadalupm is short and is often distinctly confined to the anagerontic substage. Some of the specimens of this form are very closely similar to P. si/rtale. This last species has, however, so far as known, no stage in which the venter resembles that of fiuadalupce, i. e., in which the venter becomes broadened out while the ventral lines of tubercles and the lateral nodes are still preserved in nearly their full development. This form is obviously an exact parallel with the P. pseudosijrtale said to be found at Fort Worth," liut from this it is separable by the involution which is more considerable and follows the inner line of tubercles. There are dwarfs belonging to this species which have more pronounced tuberculations than Placenticeras neivherryi, but these approximate very closely to the specimens from Presidio del Norte, and show that these last are really another grade of modifications having the same general tendency. Locality: San Carlos, Presidio County, Tex. Age: San Carlos beds. Upper Cretaceous. Placenticeras sancarlosense variety pseudosyrtale Hyatt. PL XXXII; PI. XXXIII. fig. 1. The type of this variety is a well-pi'eserved cast 200 mm. in whole diameter. The last -v^olution from lines of involution to venter, although mucli affected by senile contraction, is 80 mm. and the same volution oppo- site is 65 mm. The veutro-dorsal diameter is 73 mm. about half way the length of the living chamber, and the transverse diameter is 53 mm., avoiding the tubercles. The same ventro-dorsal diameter at last septum, taken always from line of involution to venter, is 63 mm. and the transverse, avoiding the tubercles, is 43 mm. The tubercles of first inner row alternate o See note on p. 202. PLACENTICEKATID.E. 201 with those of the opposite side ; the outer vow is more luimerous than the iuner, and there are shght indications of bifurcated ridges of costfe con- necting them on the cast. The ventral tubercles are irregularly alternate with the second row and there may have been ridges bifurcating more or less between these, but there are no indications of these on the cast. It is very like Morton's species, but the gerontic stage begins later and the increase of the ventro-dorsal diameters is much more rapid. The width through the umbilical shoulders is greater at the same age and the lateral zones flatter and more convergent, owing to the greater prominence of the umbilical shoulders. The ventral lines of tubercles are more elongated, not so close together, and quite different, and the second inner line of tuber- cles is less prominent and nearer to the vertical lines. The inner lines ot tubercles do not appear until the ephebic stage and are at first very minute but rapidly enlarge in the remainder of the ephebic and gerontic stage, disappeaiing suddenly before the outer ones at the beginning of the para- gerontic substage. They recede from the umbilical shoulders outwardly in the 23ai"ephebic and gerontic stages and have an inner costation or ridge inclined ajjicad. The outer line of tubercles disappears in the paragerontic substage immediately after the inner line. The ventral lines of tubercles disappear on the cast in the metagerontic substage. These tubercles are present on a bit of the thick ventral shell in the ephebic stage. These are almost linear, alternating and widely separated, and border a slightly concave ventral zone, which is, however, flat upon the cast at the same age. The ventral zone continues well defined and flat upon this cast until quite close to the aperture in the extreme of the paragerontic substage. The contraction of the gerontic volution is very marked, beginning, even in the parephebic substage, before the gerontic septa appear and apicad of the base of the gerontic living chamber. The sutures have the aspect of those of sijrtalc, but the outlines are more complex and the third lateral lobes longer and more pointed. This does not appear to be due to greater age, but correlates with the larger size and other differences in the form and development of tins specimen. There are eleven lobes and twelve saddles on each side in ana- gerontic septa; the innermost saddle is narrow and apparently entire, all the remainder divided and bifurcate except the first laterals. In these the 202 PSEUDOCERATITES OF THE CRETACEOUS. iuuer arm extends inwardly and, being itself bifurcated, gives a trifurcated aspect to each of these saddles. The inner lobes are bifurcated and broaden outwardly, being somewhat lilunt or rounded except in the third lateral, which is pointed and apparently of the bifurcated type, as are also the other lobes. The last four sutures are moi'e or less approximated, and the last two and part of the third interfere, as in P. placenta, except near and on the ^-enter. The living chamber is one-half of a volution in length. The outer part of the aperture is preserved, showing a blunt, broad, rounded ventral crest, or slight rostrum, ventro-lateral sinuses on the second line of tubercles, and the appearances indicate broad lateral crests, but the margins were broken away inside of this. The approximation to P. scmcarhsense is so close that probably most paleontologists will prefer to consider them identical, l)ut the lateral nodes are larger and moi-e quickly developed and the ventral tubercles more elongated and more widely separated. The extremelv thick shell is shown as well as the fact that the ventral tubercles are not more prominent on the thick shell than they are on the cast. Locality: Fort Worth, Tex." Af/e: Probably same as guadcdiqm and sancarlosense. Placenticeras planum n. sp. Hyatt. PI. XXXIII. tigs. 2-4: PI. XXXIV. This is also a part of the collection made by Stanton and Vaughau. This species also grades into P. sancarlosense although very distinct from (fnadalupce. The sides are almost smooth, the tubercles being verj- small and obscure, except in the umbilicus. The affinities for (juadcdupce and its aUies are demonstrated by Mr. Stanton's care in collecting this line series. The flat, compressed aspect of tlie young is maintained until the shells reach a diameter of "221 mm., and the venter does not show any Ijroadening out until after the shell reaches the gerontic stage. One of the specimens from Presidio del Norte, No. 21651, is 240 mm. in diameter. Four-tifths of the outer volution is in the gerontic stage, but the first piu-t of the pare))hebic substage shows the venter still narrow, flat, and tuberculated. It then becomes rounded, but the volution still remains com- "Mr. Stantou has commented as follows upon this alleged locality: "P. mncarlosense var. pseiidosyrtale, labeled ' Fort Worth, Texas,' must have come from some other place, though possibly in that region." (See note on P. ijucKlolupa.) PLACENTICERATID.E. 203 pressed. There are small tubercles in the umbilicus but these disappear in the older stages, and almost the entire outer volution is smooth. The other specimen has similar characters, and tlie sutures are of the fiuadalupce and syrtale type. This species is not separal)le in some varieties from P. neirhrrri/i, except by the absence of large lateral nodes at all stages. LocaUtij: San Carlos, Presidio County, Tex.; Presidio del Norte, Mexico. Age: San Carlos beds. Upper Cretaceous. Placenticeras newberryi n. sp. Hyatt. PI. XXXI. tigs. 3-.X The type is a cast with small patches of shell. Diameter is 120 mm., to which must be added perhaps 5 mm. for depression of outer volution. The diameter of the whole coil one-fourth of a volution younger and not altered by depression is 94 mm. The outer volution at aperture is 54 mm. and transverse is 39 mm., the umbilicus is 24 mm. and the opposite part of same volution is 42 mm. and transverse 28 mm. The last volution begins with transverse diameter of 19 mm., enlarges in the next quarter of a volution to 28 mm., and just beyond this the large gerontic tubercles begin. The transverse diameter continues to increase until the last quarter apicad of the aperture is reached, and then it diminishes between the two last tubercles, which are wideh- separated, and still further diminution takes place at the aperture. In another specimen there is no diminution in the rate of growtli of the transverse diameter apparent to the eye, but this specimen has not a complete living chamljer. The almost scaphitean aspect of the liAang chamber in some specimens is misleading and is in part due to depression. Nevertheless, this only exaggerates the gerontic metamorphoses of this interesting species. Small nodes are present in an early ephebic substage on the umbilical shoulders and continue to increase, becoming veiy large suddenly in the anagerontic substage. Elongated tubercles are present on either side of the venter in the ephebic stage, but the age of introduction was not ascertained; apparently it is later tha*n that of the tubercles on the umbilical shoulders. The latter are widely separated at all stages, but the ventral tubercles are close together. There are very obscure fold-like costae, some of them 204 PSEUDOCERATITES OF THE CRETACEOUS. (liehotoiiious, on the outer part of the outer volution on the cast, but these liave no perceptible middle row of tubercles in the ephebic stage. The venter increases in the gerontic stage from being 5 mm. wide between the lines of tubercles to 20 mm. on the first half of the outer volution, and this continues to grow broader and more convex until near the aperture, where there is an apparent diminution. As the venter broadens, the costse are brought to the edges of the venter and theii- terminations become enlarged into rows of nodes as the geroutic stage progresses, but disappear hi the paragerontic substage as the venter broadens and the sui-face of this becomes smooth on the casts. The living chamber is somewhat less than one-half of a volution in length. It has very deep sinuses on the umbilical zones and prominent lateral crests. The form of the ventral margin was not seen. The umbihcus is deep, the internal volution visible, the umbilical shoulders are prominent, and the umbilical zones are steep and broad, as in other species of this genus, from a comparatively early age. The sutures are of the guadalupaean syrtale type and well separated, becoming approximated only in extreme age. There is only one change, however, of considerable interest in the gerontic stage due to the broaden- ino- out of the venter. The ventral lobe does not broaden in the same proportion, and consequently in this stage the first pairs of saddles and finally first lateral lobes become included within the outer line of tubercles, thus becoming transferred to the venter, as in P. f/uadalupce. Another specimen (No. 11975 a) from the .same locality is more compressed, has somewhat less prominent tubercles, and not so deep umbilicus. In the interior of the type specimen the venter of the later part of neanic stao-e with shell on is exposed. This shows the usual compressed form of this stage in other species of this genus, the venter narrow, smooth, concave, as in Protengonoceras, and the volution also resembhng that of that species, but at this time it is of course more discoidal. The largest specimen of the more ec^mpressed variety reaches a diameter of 134 mm. through the base of a living chamber and when complete must have been considerably larger. I have separated neivherryi from P. })lanum after some hesitation, because of the (mtire absence of the peculiar tuberculated zone of gitadahquc on the broadened venter of the geroutic stage, the more obscure tubercula- tions, and the more compressed young. The second row of nodes is more PLACENTICERATID^. 205 persistent in the type specimen than in other fossils, and this may he a specific character, although the condition of other casts does not enable me to determine this. Locnlitij: Presidio del Norte, Chihuahua, Mexico. Age: Probably same as guadalupce. Placenticeras syrtale (Morton). PL XXVII, figs. 1.5-17; PI. XXVIII, figs. 1-6. Ammonites syrtalis Morton, 1834, S.ynop. Organic Remains, pi. 16. Morton's original specimen is probably a dwarf. At any rate, the shell is in its anagerontic substage, and the large nodes given in Mortoii's figure belong to this age. The diameter is 75 mm., and it is consequently smaller than the specimen of var. halei below described; nevertheless the gerontic stage has begun, as is shown by the great enlargement of the last pair of tubercles and the depression of the venter, and there is no living- chamber. "When this was present, the diameter was probably about the same as in the Alabama specimen. The tubercles appear earlier than in var. halei and are larger at the same age. A specimen from Fort Worth, which shows the typical characters oi the figure given by Morton, is 97 mm. in diameter. Tlie outer volution is 42 mm. from line of involution to venter and the opposite is 31 mm. The large size of the umbilicus is due to the recession of the outer volution, which is in its metagerontic substage, and the shell consequently was almost wholly outgrown. It has the large inner nodes, and as these are not so numerous as the next outer row of smaller ones there is a distinct aspect of bifurcation in the fold-like costae that here and there connect them tlu-oughout the ephebic and gerontic stages. The venter has a narrow, concave zone bordered by elongated tubercles forming a crenulated border on either side in the epliebic stage. These are more closely set than in var. halei from Alabama. The inner row of nodes, as in P. intercalare, does not hold to the line of the umbilical shoulder, but recedes outwardly in the gerontic stage, and this stage comes in much earlier than in intercalare in all of these specimens. The venter has become rounded on the outer quarter of the last volution, the ventral line of tubercles being lost. The lateral nodes, however, remain pi'ominent, showing that the last or paragerontic substage of senile development has not been reached. The outer row is nearer to 206 PSEUDOCERATITES OF THE CRETACEOUS. the venter at all ages than iu P. intercaJarc, and the volutions are stouter in all specimens of the latter that approximate iu their markings to this species. The sutures of syrtale at the same age as that given by ]\Ieek (Invert. Pal., p. 471) have the same broad first lateral saddles, but the other saddles are not so wide as those figured. There are, however, the same number, viz, 10. They are all minutely digitate except the tenth, which is entire. The living chamber is fully one -half of a volution in length, and part of the aperture preserved shows a broad, blunt lateral crest. This form is obviously very similar to P. intercalare and may be, if one chooses, considered on one side to be identical with P. sancarlosense and on the other with P. intercalare. From the former it can be separated by the venter, which is not so broad at any stage, and by the early disappearance of the ventral tubercles in the gerontic stage, and the fact that the venter becomes rounded only in extreme age and is never flattened as in neivherriji and its close ally, sancarlosense. It can also be separated from intercalare, 1)ut the characters are more dubious It is certainly so close that the differences in the specimens so far known might be considered as due to the same causes that dwarfed the stature of the shells.- The young, however, appear to be more compressed at the same age in syrtale. Locality: Greene County, Ala.; Fort Worth, Tex. Age: Probably Taylor marls or Austin limestone. Upper Cretaceous." Placenticeras syrtale var. halei Hyatt. PL XXVII, ligs. 16, 17; PI. XXVIII, figs. 3-6. This is found in the Hale collection (Boston Society Natural History, No. 8577), and approximates to polyopsis of Dujardin. It has, however, much heavier lateral nodes and costiB in the gerontic stage. The young in the later neanic stage, judging from the fragment studied, can hardly be « ilr. Stanton has most obligingly written as follows: "Locality: 'Fort Worth, Tex.' It is not at all probable that the specimen came from Fori Worth, though it may have been found some miles east of there. "Age: Upper Cretaceous, probably Taylor marls or Austin limestone. " Pldcenliccras syrtale var. Iialei Hyatt. "Locality: Greene County, Ala. "Age; This specimen is probably from the Eutaw beds, which are probably very near the horizon of P. yuadalupir, in Texas." PLACENTICERATID.E. 207 sepai-ated from the young of P. holli, although the tubercles of the inner line are less prominent at diameter of 45 mm., the volution being 23 mm. and greatest transverse diameter 11 mm. When the volution is 43 nun. from lines of involution to venter in same cast, the nodes in both lateral lines are very large and the ventral tubercles large, the ventral zone becoming sinuous on the cast in consequence of their size and arrangement. The venter also begins to show rotundity immediatelj^ after this, thus introducing the gerontic stage; the lateral zones begin to lose their flattened aspect, becoming more convex, the umbilical shoulders becoming correlatively rounded. Tlie inner lines of nodes in this species are also apt to be elon- gated into ridges directed apically, as in polyopsis Dujardin. In the parephebic substage the -s^olution from line of involution to venter in cast is 41 mm., transverse diameter between nodes, which are not close to umbilical lines of involution, as in earlier stages, but about 14 mm. distant, is 26 mm., and through the nodes, which are probably somewhat worn down, it is 30 mm. In a more complete cast of 90 mm. in whole diameter, which has lost a trifle on the venter by weathering, the same rounding of the venter begins when the volution reaches about 32 mm. in ventro-dorsal diameter from lines of involution to venter. The nodes enlarge rapidly in the parephebic and gerontic stage of these two specimens, and fold-like costse appear whicli are obscurely bifurcated at the inner line of tubercles. The inner nodes are elongated, and have heavy, although not very prominent, folds on the umbilical zones which bend sharply apicad. The ventral zone gives place to a rounded area, as in the above, and the inner nodes are about 10 mm. distant from lines of involution instead of being only a few millimeters removed, as in earher stages. They are, however,- still on the umbilical shoulders, and, therefore, in same position as in the young with relation to the sides. Locality: Greene County?, Alabama. Age: Eutaw beds. Upper Cretaceous. Placenticeras intercalare Meek. Pis. XXXV-XXXVII; PI. XXXVIII, fig. 1. Placenticeras placenta var. intercalare, Meek, 1876, Mon. U. S. Geol. Surv. Terr., Vol. IX, pi. 23. This was identified by Meek with placenta, but its characteristics were fully given by him and its relations to Ammonites siirtalis of Morton and 208 PSEUDOCERATITES OF THE CRETACEOUS. the true placenta correctly defined. In some parts of his text he also speaks of this as " Placenticeras intercalare," so that he is the sole authority for the combined names as used in this description. The ventral lobe as figured by Meek is very distinct from that of P. ivhitfieldl, as are also the entire sutures. This lobe is narrower, the branches are of the syrtale type, the siphonal saddle is more elevated, nar- rower, and is subdivided by a median marginal lobe with a minute bifid saddle; but these distinctions, except in a general sense, do not hold, since there are the same types of siphonal saddles in whitfieldi. The drawings by Meek, when compared with the originals, are accurate. The specimen on plate 23 is in the ephebic stage. The sutures overlap as much as in whitfieldi. A specimen having external shell in part preserved, from near Black Hills, South Dakota (purchased from Professor Ward), is 208 mm. in diameter. The last part of outer volution from lines of involution to venter is 112 mm., the first of the same being 50 mm. The greatest transverse diameter of the volution when it is 95 mm. is 44 mm., and when 50 mm. it is 29 mm. The volution is somewhat stouter than in ivhHfieldi and the involution somewhat less. The venter is a little broader and is bordered by two rows of tubercles of good size. These tubercles quite suddenly show decrease in size, and become much nearer at the same time on the last of third and on fourth quarter of this volution. They are present on both cast and shell. On the last part of outer volution they are almost obsolescent. On the fiirst part of the living chamber they are oj^posite, then become again alternate, and as they decrease in size are again opposite. The ridges on the venter are slight, except in one short space, where they first become opposite. The shell has numerous bands of growth. The chevrons are particularly prominent on last part of this volution and run into and form several longitudinal ridges on the outer half of lateral zone, while the costse. are represented only by very broad, hardly perceptible, folds. The tubercles of the middle line are of good size and become obsolete on the last quarter, changing at the same time with ventral rows of tubercles. Large tubercles are present on the umbilical shoulders, which sensibly decrease at the same titne and also recede gradually from the shoulders outwardly. These nodes are elongated, forming parts of the costa' tliat are more perceptible in their neighlior- hood. The outlines of the ventral zone are not sinuous between tuberch-s. PLACENTICERATID^E. 209 There is a thick, opaque, honi-colored outer layer', an intermediate crimson-red layer, and an inner naci'eous layer of the usual color. These consist of a number of minor layers as in other shells of this genus. The sutures have broader lobes and narrower saddles than in ivhitfieldi and placenta, and the outlines of these are somewhat less complicated and not so overlapping. The ventral lobe has the same narrow character and syrtakA^ke branches, with large siphonal saddle, as in Meek's figure of P. intercalare, but the siphonal saddle is smooth and entire on the venter, as in P. tuhiffietdi, and also has the same minute marginal saddles on either side of this entire center. A fine young specimen of this species, from Sage Creek, South Dakota, No. 2104b in collection of Yale Museum, at diameter of 80 mm., shows the beginning of the large tubercles of umbilical shoulder, the ventral tubercles, and apparentl}' those of the middle row to be on the first quarter of its outer volution. This shell must have been smooth and similar to P. placenta, perhaps, even in tlie sutures, when tlie diameter from line of involution to venter was about 15 mm. At later stages the sutures are distinct. Another specimen, same locality and collection, at diameter of 132 mm., shows three rows of tubercles distinctly visible on botli cast and shell. No 2104a. The median lateral lines of tubercles disappear on the last quarter of the outer volution in this specimen, but the ventral inner rows persist. As long as the median rows of tubercles exist the .shell has a transverse outline distinct from that of whitfieldi at any stage, but when these disappear it is difficult to separate this specimen from H-hitJieldi. I have not yet seen a specimen in which the ventral rows of tubercles disappear, l)ut whether they do or not it must be impracticable in some specimens to separate them from whitfieldi xav. tubercidatum, although most specimens are distinct on account of the size and persistence of all of the tubercles. A fine specimen from same collection from Sage Creek, South Dakota, (No. 1863) at diameter 144 mm., has already passed well into its gerontic stage, whereas the specimen figured by Meek is not so far advanced in ao'e. The first part of the last volution is considerably compressed, as in Meek's figure, but on the living chamber on the last half of this volution the whorl becomes stouter. This chamber is apparently nearer complete and aliout one-half of a volution in length. All three lines of tubercles persist and the ventral ones which are alternate in tlie ephebic stage are apjiroximately MON XLIV — 03 14 210 FSEUDOCERATITES OF THE CRETACEOUS. opposite ill old age ami are sometimes connected by a ridge, so that the venter is serrated. The inner line of tubercles recedes in this stage, as in specimen figured by Meek. The sutures have shorter, stouter saddles than those figured by Meek, and are more like those of P. syrtak. In the first lateral saddles especially thev are more deeply cut into by the lobes that broaden out apicad, and the other lobes and saddles are like those of Intercalare, as figured by Meek. The resemblances to syrtale occur more markedly in old age, when the body of the first lateral saddles loses the thread-like tenuity of the ephebic stage and becomes thicker. All the saddles do not show these changes equally. This last specimen has enabled me to make connections with No. 18975 U. S. National Museum, from the Upper Missouri, which is a nearer approach to syrtale. The inner nodes on this last are about the same, but are not partly buried by the involution and make their appearance some- what earlier in the neanic stage. The outer line of tubercles are larger and the venter is broader. The sutures, however, and the proportions, etc., of the volutions are about the same. Lastly there is a fragment in same collection, locality No. 1720, 5 miles southeast of Harpers Station, Laramie Plains, Wyo., that no one would think of separating from syrtale by the external characters. The diameter is 94 mm., and the specimen has the same wide umbilicus, stout volutions, prominent nodes, and sharp ventral tubercles as that species. The sutures, however, although the .specimen is so small, are almost as excessively complicated in outlines as in Meek's figure, although this was taken from a much larger volution. One specimen. No. 9735, U. S. National ]\Iuseum, from Ponil Canyon, New Mexico, has characters just intermediate between P. intercalare and P. placenta. The young and full e^jhebic stage has the form of the stouter specimens of intercalare with three rows of tubercles. The two outer rows are, however, more delicate than usual in intercalare, especially the median lateral ones, wliich are very small and widely separated as in P. jilaceiifa. Unfortunately the last of the ephebic and the first part of the gerontic stages are missing, but the parts left show similarity with the old age of P. placenta and intercalare. The venter does not broaden out except very slightly wliile becoming rounded as it does on the third quarter of the outer volution. The sides lose the abrupt elevated umbilical shoulders and become evenly convex, but the involution continues to follow the umbilical PLACENTICERATID.E. 2 1 1 line of tubercle.s. The ventral lines of tubercles persist on the outer volution, but are very faint and tiually disappear. The same is true of the other lines of tubercles, all of which finally disappear in the paragerontic stage. The shells of this species do not apparently have the gerontic enlargement of tubercles into heavy blunt nodes which is common in ffiiadalitjue and its allies, sancarlosense, planum^ and also 5^rto/e. The sutures are like those of syrtale and less complicated than in intercalare at tlie same age, but this appearance is probably largely due to the fact that they are less crowded and do not overlap. Locality: Black Hills region. Age: Fort Pierre group, Upper Cretaceous. Placenticeras placenta (Dekav). PI. XXXIX. figs. 3-6: PI. XL. fio-,s. i. ± Ammonites placenta Dekay. lS:iS. Ann. New York Lvc. Nat. Hist.. Vol. II, pi. 5, fig-. :?, not fig. 3. Placenticeras 2>ltt^ent a Meek (pars), 1876, Mon. U. S. Geol. 8urv. Terr., Vol. IX, p. 465. Placenticeras placenta Whitfield (pars). 1892. Mon. U. S. Geol. Survey, Vol. XVIII, pis. 40, 41. This species is represented in the Museum of ( 'omparative Zoology by a large fragment from New Jersey 101 mm. in diameter from line of involution to venter at base of living chamber, and this last is about one-half of a volution in length. It is a cast and smooth on the sides, with the exception of a line of fold-like tubercles on the depressed umbiHcal shoulders. The ventral zone, even at this stage, obviously fully gerontic, is flat and 7.5 mm. broad as estimated. The last sutures have not so highly complicated outlines as whitfiehU, but the lobes are long and narrow, the first and second laterals highly inclined apically. The fourth lateral is about two-thirds as long or only slightly shorter than the third lateral lobe. The saddles are not so deeply divided as in tvkitjieldi and broader and more solid. The last two sutures are approximated, but the third, although partly preserved, is at the usual distance and shows that this is not the same as the western form described by Meek as placenta. The sutures of this large specimen of P. placenta have exactly the outlines given by Whitfield in his figure, and a similar, 212 PSEUDOCERATITES OF THE CRETACEOUS. altliougli perha23S older, siphonal saddle has numerous denticles or marginal saddles. The median marginal lobe was not quite so plain as in Whitfield's figure, but this might have been owing to age or variation in sutures or the condition of the cast. Meek, as well as Whitfield, included under placenta several species which are separated in these descriptions, but Whitfield recognized- and described the differences between the western and the New Jersey specimens and considered them as probably distinct. I have consefpiently named the western species whitfieldi in recognition of this fact. The specimen described above enables me to add the following: The venter is not rounded on the smaller end of this cast, but flat, having the same form as whitfieldi, but broader than in that species; subsequently, although not well preserved, this part appears to become rounded. This specimen shows that in extreme age the volution is shorter and has more gibbous sides than in whitfieldi and shorter ventro-dorsal diameters. The decrease in involution due to senility is also more marked, and takes place at a smaller size. This species stands between si/rtale and whitfieldi in this respect and in its sutures and other characters. There are several fragments in the Hale collection of the Boston Society of Natural History, supposed to be from Greene County, Alabama, which have saddles with more solid bodies or basal parts, as in true placenta These indicate a species of larger size than the associated species of P. si/rtale, having volutions with smooth flat sides and smooth venter, as in placenta. The sutures agree very closely with those given by Morton for P. placenta from the cut of the Delaware and Chesapeake Canal, and one specimen shows a rounded venter. The examination of the fine suite of original types and specimens in the Museum of the Academy of Sciences of Philadelphia gave the following results: The septum of this species is much flatter, ha\T[ng only a very slight double curvatui-e ni place of the very marked double curvature of whitfieldi, and this is less apparent on the suture line than on the surface of the septum. On a volution 63 mm. from line of involution to venter, transverse diameter is 22 mm. and there are three lines of tubercles. The lateral row is two-thirds of the breadth of the sides, nearer the venter than the dorsum, and very small and widely separated, but still quite distinct. The tubercles on the venter of placenta are large and elongated like those of holli and much coarser and PLACENTICERAT1D.E. 213 less numerous tlian in some specimens of whitfiekU. These disa^jpear in the ephebic stage, together with the lateral line of tubercles, and in some specimens the latter may be entirely absent as in young specimens figured by Whitfield. The large originals of Morton's figure and of Whitfield's show these figures to be approximately correct. The venter is in all stages broader than in true ivhitjieldi, but remains flat only through a small j^art of the gerontic stage. In two specimens, 365 mm. and 425 mm. in diameter, one Morton's type, trom cut of Delaware and Chesapeake Canal, the living chamber was practically complete and about one-half of a volution in length. The rounding of the venter begins in these on the still separate part of the second quarter of the outer volution. Near the aperture the venter is completely rounded and the decrease in the ventro-dorsal diameters between the lines of involution more marked than in whlt/ieldi, and the umbilici are consequently larger. The sutures vary from having very solid- looking saddles as in Whitfield's figui-e to those with the first to third saddles almost indistingviishable from those of some varieties of tvhitjieldi. Upon the whole, however, it is safe to say that while the saddles of placenta may be as deeply undercut and the necks as thin as in whiffieldi, the basal parts are, perhaps, always less completely cut up by the marginals. These and the auxiliary saddles have, however, as a rule, a bifid aspect with a large median marginal deeply dividing them, and this seems to be a distinc- tion of more importance, especially in the aspect of the auxiliaries. The proportions of the diameters are also quite different. In the ephebic stage the transverse diameter may be more or less than one-third of the diameter from line of involution to venter and in old age it may be more or less than one-half of this same diameter. A yomig specimen of diameter of about 60 to 65 mm. is in collection of the Academy of Sciences of Phila- delphia. In the neanic stage this cast had highly compressed smooth volutions as in ivhiifiehU, but the umbilicus is larger, the involution being- somewhat less, apparently. The three lines of tubercles begin on the first part of the outer volution or just before, when the shell is about 45 mm. in diameter. At this stage the lobes and saddles are distinctly placenticeran. The saddles are all bifid, but the entire outlines have given place to com- pletely denticulated outhnes over both lobes and saddles, even on the innermost auxiliaries in the older parts of this cast. The sutures at this age are very similar to those of syrtale and guadalupce. 214 PSEUDOCERATITES OF THE CRETACEOUS. Until a late age this shell is separable from stantoni or psendoplacenta by the preseuce of the minute median lateral line of tubercles. Tlie larger size and wider separation of the ventral tubercles separate the younger stao-es, in which the venter is often very narrow and the sutures similar to those of tvJdtfieldi, from var. tuberculatum of that species. The sutures, however, as a rule, liave less complex outlines and more solid-bodied saddles and less concave septa, as stated above. LocalHy: New Jersey, Alabama. Aye: Matawan formation (clay marls), Upper Cretaceous. Placenticeras stantoni n. sp. Hyatt. Placenticeras placenta Stanton (pars.), ISiM. Bull. U. S. C°ol. Survey No. Kni, pi. 39, figs. 2, 3, not fig 1. Locality: Upper Kanab Valley, Utah. Age: Colorado epoch. Upper Cretaceous. Placenticeras stantoni variety bolli Hyatt. PI. XL, figs. 3-7; PI. XLI: PI. XLIl: PI. XLIII. figs. 1. ± Placenticeras intercalare Meek (par^s.), 1876, Mon. U. S. Geol. Surv. Terr., Vol. IX, p. 471. This species is very like P. placenta and irhiffieldi, but has much stouter volutions with broader venters at the same age and is intermediate in character between intercalare and whitfieldi. The costse are of tlie syrtale type, but are merely obscure folds on these casts. The tubercles are sparse and on the umbilical shoulders as in placenta. The costa^ are occasionally bifid on the outer part of the side with single ones between them. Tlie elonofated ventral tubercles are alternate and each one has its costation. The sutures have much shorter lobes and stouter, shorter saddles than in placenta. The young in the nepionic stage have a smooth volution with rounded venter. In the neanic stage this changes through the elevation of the venter. The ventral zone is at first quite broad comparatively and perfectly flat in the neanic stage. In the ephebic stage it becomes much naiTower and con- cave and probably then acquires its tubercles. The tubercles on the umbilical shoulders do not appear until this stage begins. PLACENT7CERATID.E. 215 The lateral augles of the single costai, and still more the junctions of the dichotomous costse, when these occur, tend to rise up more ^prominently than the rest of the costatiou as in other forms, but they do not in the specimens examined, as in syrtale and interculare, become tuberculose. The specimens from which these descriptions were taken are in the Museum of Comparative Zoology. This species is distinguished from P. placenta by the shorter and stouter lobes and saddles and the better separation of the sutures at all stages except, perhaps, the youngest. It stands apparently nearer to P. syrtale in its sutures than to intercalare, but this is due to the fact that in intercalare the sutures vary from those like syrtale to as complicated as iu Meek's figures, and if the comparisons are made with the former, it is seen that the external characters and sutures place it between intercalare and ivUtfieldi, on account of the suppression iu both of the lateral line of tubercles. A speci- men from Dallas County, Tex., has similar markings and sutures so far as seen on the young volutions, and is probably the gerontic stage of this species. It is an incomplete living chamber al)out one-half of a volution in length, witli the inner volutions attached l)ut l)adly crushed. The latter shows the large inner row of nodes and the sutures in part, and these last agi-ee closely with those of the specimen described above. The volution from line of involution to venter at base of living chamber is 75 mm. in diameter, transverse diameter about 40 mm., and at one-fourth of a volution distant from this the diameter is 91 mm. The venter is broad, and the ventral zone convex on the cast at the two last septa. The tubercles are almost obsolete and the cost£e completely gone, the cast being smooth with the exception of one obscure broad longitudinal ridge on the centrau surface of the lateral z(jne. The remnants of tubercles are shown in obscure and very slight folds with a decided apical trend. This desci-iption shows that the gerontic stage is quite distinct from that of placenta or ivhitfielcli. The basal suture is very complex in its outlines, but has the short saddles and lobes of this species. The next younger septum is, however, closely approximated to the last. The first and second lateral lobes are very narrow and the saddles approximate. The lateral lobe is also narrow. The remaining lobes and saddles are more like those of the younger stao-es, but also have narrower lobes and broader saddles. These suture's are quite 216 PSEUDOCERATITES OF THE CRETACEOUS. distinct from tliose of other species and come nearer to those of the old whorl of P. placenta from New Jersey than any other fonn. They are, however, smaller, and the apical trend of the outer lobes is less, the third lateral being' shorter, and the remaining lobes more abruptly separated through their extreme shortening up as compared with the third lateral. Having received through Professor Mai'tin the specimen described by Meek from Tarrant County, Tex.," as belonging to P. intercalare, I am able to state that it is a good cast of this species. The diameter is 90 mm. The living chamber is incomplete but nearly half of a volution in length. The median lateral line of tubercles is absent, the inner line of small tubercles recedes from the umbilical shoulder, and the ventral tubercles are rather coarse and large, and the venter broad as in typical holli. The sutures have the solid short saddles and short lobes of this form. The paraphebic substage is reached near the aperture. LocaUUj: Elm Fork and West Fork, Dallas County and Tarrant County, Tex. Aye: "Probably Eagle Ford shales" (Stanton) Placenticeras pseudoplacenta Hyatt. PI. XLIII, figs. 3-11; PI. XLIV. Placenticeras placenta (?) Stanton (pars), ISOi. Bull. U. S. Geol. Surve}' No. 106, pi. 39, fig. 1 (not figs. 2, 3.) The sutiu-es are peculiar and unlike those of any of the forms of true P. placenta or ivliitfielcli. This fact was noticed by Stanton, who considered the Colorado species to be different from true placenta. In confirmation of these remarks I can add the following: A large fragment, U. S. National Museum, locality Upper Kanab, Utah, No. 22344, diameter from line of involution to venter 88 mm., greatest transverse about 35 mm., shows a wider venter 6 mm. and flatter than in irhitfielcli at same age. The side which is unaffected by pressure is nut so evenly convex as in that species, the outer part being very slightly concave, the centran part slightly gibbous. The sutures exhibit more complicated outlines than in the younger stage figured by Stanton, but they have similar ragged outlines and very broad lobes and are obviously the same. A specimen with diameter of 35 mm. has on the last volution sutm-es with same rugged «Mon. U. S. Geol. Survey Terr., Vol. IX, j). 471. PLACENTICERATIDiE. 2 1 7 aspect but very much simpler in outline than those of P. whitfieMi or even those of true placenta at the sr«me age. The perfect venter at this stage is concave and it continues smooth and concave in this species until the shell is much larger, but then becomes flattened and apparently exactly similar to that of true P. placenta, but is broader at the same age and flatter than in P. whitfiekU. The sutures are more like those oi P. placenta than those of P. whitfieldi. The casts do not show the shell except in the young stage and this has obscure sigmoidal bands of growth like those in whitfieldi but no costfe on the shell and none on the casts as is usual in that species. The youngest stage is more involute than in P. placenta and is like some specimens of P. whitfieldi in this respect. Stanton's figure of the suture was taken from the ephebic volution of a specimen of the diameter of 173 mm The volutions were perfectly smooth on this cast, with a flat, broad venter, and at the diameter given on the third quarter of the outer volution the gerontic stage had begun and the last part of the volution was helmet-shaped in section with a rounded venter. This shows a paragerontic stage earlier than is usual in ptlacenta or in irhiffieldi. The specimen alluded to by Stanton, from Ellis County, Tex., Eagle Ford shales or Fort Benton Group, is a cast 1?1 mm. in diameter, with form almost as much compressed, and with thin venter, as in whitfieldi, but the sutures are more like those of stantoni. They are, however, more deeply cut, being older than those figured and more like those of whitfieldi. In fact, I do not see here nor elsewhei'e any possibility of drawing- sharp lines, except between the genera; the species all run into one another. Locality: Upper Kanab, Utah; Huerfano Park, Colorado. Age: Colorado Epoch, Upper Cretaceous. Placenticeras pseudoplacenta variety occidentale Hyatt. PI. XLV, figs. 1, 2. The saddles and lobes have the elongated forms of those of P. whit- fieldi, but are more solid; the ventral lobe has the same elongated arms, and the ventral saddle is also similar, but the lobes and saddles are simpler and more like syrtale until a later stage than in P. whitfieldi. The shells have a row of tubercles on the umbilical shoulders and fine tubercles on the venter. The principal distincti(ju is, however, the breadth of the venter 218 PSEUDOCERATITES OF THE CRETACEOUS. and itfi flatuess in the ephebic stage, which is simihir to stantoni and jjlacenta. There are, howe^•er, some specimens witli smooth A-enter, as in tvhifjieldi. A specimen in the collection of Colmiibia University, New York Citv, No. 10622G, from Upper Missonri River, has a diameter, ])artlv estimated, of 150 mm. Tlie last volution, with living- chamber, is 76 mm., partly e.stimated; the umbilicus is 22 mm., and opposite the same volution, from line of involution to venter, is 52 mm. The vofutiou is not so flattened or compressed, having slight ventral tubercles and slight!}- more gibljous sides than in irhiffieldi, and volutions not so deeply involute, as is shown by the breadth of the umbilicus. The line of involution is outside the line ot internal tubercles, and this more open a.spect of the umbilicus and tlie solid aspect of the saddles and forms of the lobes agree more closely with the smaller form of phcenta figured l)y Whitfield and are quite distinct from true whitfieldi of the same size. The living chamber is incomplete, but occupies about half a volution in length, and the aperture follows the bands of growth. The siphonal saddle has several minute denticulations even at this early age Sutures at diameter of 26 mm., from line of involution to venter, showed distinctly the syrtale type of outline which occurs in whitfieldi, only at a much earlier stage, short, broad saddles and con-esponding lobes, with well-separated outlines and no appearance of bands free of sutures on either side of venter. No. 8238, U. S. National Museum, from Cow Island, Upper Missouri River, Fort Pierre or Fox Hills Group, is a ver}' interesting fragment of this form. It is a good-sized fragment, showing the inner and outer volu- tions, with broad ventei's and proportions stouter than in typical psetido- placenta or whitfieldi. The tubercles on the venter are not large, but quite plain. Thev disappear on the last of the outer volution, while the inner line pei'sist, and there is no median line. There is on the last part of the outer volution, in the beginning of the gerontic stage, a distinct elevation along the line usually occupied by the median lateral tubercles, which I have never seen in tvhitfieldi, and which usually occurs only in syrtale, intercalare, and the more heavily tuberculated forms. This is also apparent in the full ephebic stage, but is less marked. The sutiu'es are very similar and, in fact, not distinguishable from those of whitfieldi in some varieties. I have, in consequence, placed this shell under name of pseudoplacenta, although in general aspect it really seems to agree better with staiitoiii. PLACENTICERATID.E. 219 One specimen, a fragment given b}' Dr. R. T. Jackson, said to have come from Bad Lands, near Black Hills, South Dakota, is 73 nnn. from the lines of involution to the venter at small end, and 88 mm. at a distance of 110 mm., measured along the eentran axis of the side, or somewhat more than one-fourth of a volution farther on, the whole length being 160 nun. This fragment is a living chamber, the last septum and the aperture being partly preserved. A restoration of the whole coil shows the diameter of the entire specimen to have been about 1 74 mm. The obsolescing costaj, sparse and small tubercles on umbilical shoulders, and small, more closely set tubercles on the edges of the venter, show that this is probably the parephebic stage of this species. The venter has become rounded, or rather the previously concave zone has become convex, but the ventral tubercles, although faint, are clearly discernible at the oldest end of this fragment. Thus the gerontic stage must have begun in this species at a size when the ephebic stage was not yet completed in P. whitfieldi or placenta. The saddles of the last septum show much less complex outlines than in ivhltfieldi. The third lateral lobe was not entirely preserved, but it was obviously not so long. The outlines resemble approximately those of holli. Dissecting- out a part of the ephebic volution contained in the zone of involution, the shell and the sutures also were found perfectly preserved. The probable diameter of the volution at this age from line of involution across side to venter was about 35 mm., and the whole diameter of coil perhaps 75 mm. The shell at the younger end of this fragment, which was about one-fourth of a volution, showed a decidedly concave venter; the cast was also slightly concave. At the other end, while the shell was still concave, the cast was flat on the venter. The tubercles on the younger end were well defined, but mere fine crenulations, as in P. placenta and whitfieldi. Thev were barely perceptible on the cast at this end of the fragment, and not visible at all on the cast at the other end, although, as stated above, present on the cast of the gerontic living chamber. The sutures showed somewhat more solid branches on the saddles than in ivJiitfiekU, and ventral lobes and siphonal saddles like those of P. interccdare. Previous to cracking out this fragment the specimen was classified with variety holli. The chevron markings on the nacreous layer were beautifully displayed and very instructive. At the younger end they had the normal orad direction for about an inch, then 220 PSEUDOCERATITES OF THE CRETACEOUS. some accident had happened fracturing the edges of the aperture on both sides and causing a slight sinuous constriction on both sides when growth was resumed. Beyond this the direction of the chevron hues was reversed on the right side in a median depression and on the left along a slight corresponding elevation. One fragment from Elm Fork, Dallas County, Tex., in the Museum of Comparative Zoology, not quite one-half of a volution in length and measuring 230 mm. in diameter, has these characters, but the umbilicus does not appear to be quite so large in proportion. The aspect of the saddles enables one to separate these from var. tuberculatum of P. whitfieldi, but it is probable that these two are connected. As I have repeatedly stated elsewhere, I consider this varietal connection no argument for uniting these obviously distinct species. This specimen has large marginal saddles on the siphonal saddle, and a distinct marginal median lobe, which becomes slightly trifid in later stages. On the left side of this are entire slightly phvlliform saddles, and on the right a bifid marginal. These become subdivided later. The ventral lobe has the long arms of the whUfieldi type which are not similar to those of the same lobes in the syrtnle type. I propose, in following the indications of these observations, to confine this name to those forms of this genus having broad venters and more immature sutures than in whiffieldi at all stages of growth. The edges of the venter may be either finely tuberculated or smooth. The sides may be smooth or with a median line of very obscure elevations. The inner line of tubercles is developed, but does not appear at an early stage. Locality: Elm Fork, Dallas County, Tex.; Upper Missoui-i, Bad Lauds, South Dakota. Acje.:" Probably Fort Pierre group. Upper Cretaceous. «The following note has been kindly added by Mr. Stanton: " Placenticeras pseudoplacenta var. oceidenkde Hyatt. "Locality: Upper Missouri. Bad Lands, South Dakota. "Age: Fort Pierre group, Upper Cretaceous. "The specimen from the Bad Lands is certainly from the Fort Pierre, and the one from the Upper Missouri probably is also. "The specimen labeled 'P. pseudoplacenta var. occidentak' and also 'var. intermedium' from Elm Fork and West Fork (Horton's mill), Dallas County, Tex., if the locality can be trusted, is probably from the Eagle Ford shales, which are about equivalent to the Fort Benton." (The locality referred to is trustworthy. — A. H.) PLACENTICERATID^E. 221 Placenticeras whitfieldi n. sp. Hyatt. PI. XLV. tigs. 3-K3; PI. XLVl; PI. XLVII, figs. 1-4. Placenticeras 'placenta Meek (pars), 1S70, Mon. U. S. Geol. Surv. Terr., Vol. IX, pi. 24, %. 2. This species can be distinguished from true P. placenta of New Jersey and the supposed western members of the same species by the following characters. The highly compressed volutions are more involute and tlie venter is narrower throughout life and less completely rounded in old age, and this change comes in only at a much larger size than in the shells of P. placenta. Owing also to the absence of the median lateral line of tuber- cles the volution has flatter sides. All tubercles are wanting in typical forms at all stages, but very fine tubercles are present on either border of the venter and larger ones on the umbilical shoulders in some shells. Sometimes minute tubercles are present on the median part of the lateral aspect, but these occur only in the neanic stage, disappearing with' the ventral tubercles in the ephebic stage. The sutures are more complicated in the young and are more overlapping than in placenta. The saddles are almost linear because of the excessive development of the lobes, which are very long and narrow. These differences hold with the materials so far examined. It must be remembered, however, that as yet no examination of a large number of specimens of both species from the same locality has been made, and it is likely that there are intermediate shells. Certainly no one can distinguish these species unless familiar with both forms or having both for comparison. The same may be said of P. intercalare, between which and this species there are intermediate shells in P. whit/ieldi var. tuberculatum. I made special examination of the ventral lobes of whitfieldi in all available specimens. All had the peculiar very broad ventral lobes with long nari-ow branches on the lateral aspects except in rare cases in which Si/rte/e-like or blunter arms were present. One specimen had the lono- narrow arm on the right side and a blunt syrtcde-Wka arm on the left side. As a rule the ventral Jobe is symmetrical, but the siphonal saddle is often unequall}^ developed or out of place. This saddle is often entire and flat, so that one is apt to regard this as the normal form, but variations are so frequent that only large numbers of specimens could determine the facts. 222 PSEUDOCEKA'PITES OF THE CRETACEOUS. This saddle may have a simple median marginal saddle or be trifid with three saddles, equal or unequal in size; or it may l)e bifid, with Ijotli mar- ginals again subdivided, or of any sliape between these and such irregular sinuous outlines that it is diflficult to describe it. It is almost invarialily sunken between two marginal saddles, one on either side, but occasionally even these blend with the central part of the siphonal saddle. A specimen from Cheyenne River, South Dakota, in the collection of Columbia University, New York City, reaches 327 mm. in diameter and has the basal part of a living chamber present. The venter begins to be rounded on this living chambered part. There is a slig'ht decrease in the amount of involution at the same time, showing that this is in its gerontic stage. In 1 1 other specimens, in collection of the Boston Society of Natural History, and sent me by Ward, ranging in size from 110 nnn. in diameter to nearly the dimensions of the specimen last described, the t}'pical form was observed. No tubercles were present, and the first lateral saddles were very narrow and very deeply cut by almost straight and very long marginal lobes and saddles. In all of these there are chevron marks more or less shown, and the sutures are similar, with the exception first mentioned. The first three lateral lobes are not very steeply inclined apicad, and the fourth lateral is nearly or quite two-thirds as long as the third lateral. Altogether I have seen perhaps 40 specimens. A specimen from South Dakota, in collection of the Boston Society of Natural History, which is 113 mm. in diameter, shows the costal and the chevrons, but the costse are quite fold-like. There were no tubercles on the edires of the ventral zone nor on the umbilical shoulders. The smallest part of the outer volution was about 30 mm. and the widest part about 60 mm. from line of involution to venter. Some of the fragments of volutions examined must have 1:)elonged to shells fully 15 inches in diameter, the size of the specimen from New Jersey figured by Morton as P. placenta, but none of these showed the gerontic degenerations in the rounding of the venter as in his figure. The wider separation and the simpler outlhies of the sutures found in his figure also occur only at a comparatively early stage in this species. The ephebic staare has narrow concave venter on the thick shell and flattened zone on same area in the cast. The sides are perfectly smooth, with faint sigmoidal, almost obsolescent, costaj. PLACENTICERATID.E. 223 Meek figures a specimen just entering upon the ephebic stage, and these costte are faintly indicated. It is, in fact, difficult to see them, and thev can be felt better than seen in some specimens. The costoe are often (juite linear and distinct on the shell in the neanic stage, but are not present before or after this stage. The divaricating ridges described and figured liv Meek as lines have been described above as lateral chevrons with the apices pointing orad and occurring only on the outer thirds of the sides of the shell. They are very plain on the inner layers of shell and faintly indicated on the cast and entirely independent of the growth bands. At an older stage (probably the metephebic substage) than that figured by Meek they are quite broken ov interrupted by the bands of growth on one side where the nacreous layers are preserved, and on the other, in wliit-h part of the outer layer covers them, they are not visible. They are apparently characteristic of the neanic and part of the ephebic stage. The venter retains its flatness until the shell is very large. The sutures are really at considerable distances from each other, but the saddles are so deep and the lobes so long and narrow that the external outlines are approximated except on and near the ventei*. The first lateral saddles are straight and narrow, and there is consequently a band on either side of the venter in casts whicli is not cut up by intermingling sutures. On breaking down a specimen sent me by Professor Ward the young at diameter of 11.13 mm. from line of involution to venter had the first four saddles even at this early stage more slender and more deeply cut by the marginal lobes than in tlie specimens supposed to be young of I\ placenta of the west at diameter of 2.') mm. The lobes and saddles were also longer and narrower in proportion, the sutures nearer together, and the branches of the ventral lobe larger and longer and the ventral saddle with larger marginal lobes at exactly corresponding ages. The ventral crenulations or tuberculations are not so persistent as in placenta of the west, since they disappear in all of these specimens in the ephebic stage. The incomplete living chamber is about one-half of a volution in length. The first volution of a specimen in the collection of the Museum of Comparative Zoology, from Cliff'ord, Nebraska, has a depressed rounded goniatitic form with a single constriction in this specimen at the end of the first quarter. The lateral sutures along the sides have the broad lateral 224 PSErDOCERATITES OF THE CRETACEOUS. saddles; the others were covered and could not be seen. The only exposed suture immediately preceding the constriction has entire outline.s. The ventral lobes are moderately deep and straight-sided, with large, undivided siphonal saddle. The first lateral saddle is rounded and broad, but entirely upon the venter, as is also the first lateral lobe. The latter is also rounded and wide at base and not so deep as the ventral lobe. The second lateral is magnosellarian in outline and reaches to the small lobe formed on the line of involution. It is interesting to note that in this highly degenerate form of the Cretaceous the sutures exactly resemble at this age the adults of the Primordialidfie, which have undivided siphonal saddles, and the volution on section has the semilunar anarcestian form of the nepionie stage in Ammonitiufe." Near the end of the first volution the first lateral saddles and also the magnosellarian saddles have begun to show minute dividing lobes. The form in section has at the same time changed to helmet shape through the elevation of the venter. The zone of involution at this age begins to increase and in the next volution extends over nearly the entire side of the fir.st whorl. In consequence of the helmet shape and flatness of the sides the involution, which is about two-thirds, appears to be greater than at any subsequent stage, whereas it is proportionately less. The ananeanic substage beg'ins on the second volution. The sides become flatter, more convergent, and the venter is narrowed and flattened on the cast and slightly concave on the shell. In the metaneanic this change is completed by the rapid increase of the dorso-ventral as compared with the transverse diameter. The venter still remains quite broad and does not attain the narrow aspect of the adult until in the latter })art of the neanic stag'e on the fourth volution. The umbilical zoue begins to develop in the ananeanic substage and steadily increases in breadth and steepness there- after. The auxiliary lobes and saddles begin to appear in the paranepionic, and as the volution increases in the ventro-dorsal diameter more of them are introduced by the further division of the magnosellarian saddle, or rather what remains of this, in the umbilical zone. The process of division continues throughout the neanic stage, the additions being- made internally on the umliilical shoulders and zoue. They arise as simple indentations and grow deeper with age, the digitations being introduced gradually by - _— — . ^ . _ "The margin of the maiuiscript hears a large "?" opposite this sentence. — T. W. 8. PLACENTICERATID.E. 225 minute inflections of the outlines. The saddles are not so long as to inter- fere with deciphering the outlines of the lobes until the fourth volution is reached and the anephebic substage begins. Before this the sutures resemble more those of P. bolli, ha\'ing shorter saddles and proljably at still earlier stages they are even more like those of this species, being pi'opor- tiouately shorter and with simpler digitations. There are nine lobes present on the last quarter of the third volution. The three principal lobes have their usual proportions, and the ventral lobe is nearly the same as in the adult, but the siphonal saddle is not so prominent, and the minor saddles on the sid^ of this are also much smaller and more nearly of the same size. There are six lobes on the lateral zone, a seventh on the shoulder, and two on the umbilical zone. The saddles are all distinctly bifid, except the tenth, which is not yet differentiated. The lobes are all of the trifurcate type, except the nintli, which is not fully developed and is single or unsym- metrical. The lobes and saddles greatly increase in complication of outline and become larger and lai'ger, but the number remains stationary on the fifth volution. Meek" figures a very large suture with twelve lobes. Tubercular elevations make their appearance on the edges of the ventral zone in the ueanic stage, but they are more perceptible to the touch than to the eye. The widely separated sigmoidal costas are more distinct, but the deep apical bend is only one-half developed and ends abruptly in some with a faint tubercle. The ventral part of the bend is apparently absent on the fourth volution, but subsequently appears more decidedly on the last quarter of this volution. Internally the oral bend of these costse is also deficient in the neanic stage, appearing to be better developed in an ephebic substage. Nevertheless, when one looks at the volution, he is apt to see only the inner half of the deeper apical bend. The chevron-like folds are present on the shell in the later neanic substages and may come in earlier. A line of very faint, liprdly perceptible, tubercles appears on the umbilical shoulder on the fifth volution in an ejjhebic substage. I have been as minute in my descriptions as the specimen in hand permitted, because the presence of these indistinct tubercles and costa- in the neanic and early ephebic substages show, together with the more widely separated sutures and broader venter, that the young are quite similar to those oi placenta and have also traces of their affinity with the more heavily aMon. U. S. Geol. Surv. Terr., Vol. IX, p. 466. MON XLIV — 03 1.5 226 PSEUDOCERATITES OF THE CRETACEOUS. tuberculated and stouter forms P. bolli. The saine characters also show- that these species are not identical, since they are not so strongly developed at any stage as in other species, and are succeeded by distinct sutures in the nearly full-grown shells. This study suggests also that the western species was derived from the eastern form. A specimen j)urchased from Professor Ward, locality Bad Lands, near Black Hills, South Dakota, shows the typical sutures and form of whitfieldi. The first lateral saddles in the ephebic stage have the usual three nearly equal marginal saddles and lobes, and there are no tubercles nor any costse appreciable to the eye at diameter from lines of involution to venter of 101 mm. These sutures, however, have one peculiarit}', probably of essen- tial service to this investigation. In so far as the first two saddles and lobes are concerned, they are appreciably distinct, the first saddles being entirely free. The remaining parts of the sutures overlap more or less, as in almost all of this species. In the anephebic substage, or last of neanic stage, however, the diameter of volution being 33.5 nun., the costse are apparent and have the usual form, but are very faint. The chevrons are especially well shown in the fossil, although not more prominent than in many other specimens. They were plainly seen on this fragment, broken out of the larger volution, and there appeared to be some connection between these at their line of convergence and the indistinct longitudinal ridge or trace, which is obviously the centran lateral ridge seen in some older shells. The sutures are similar to those of the adult at the diameter of 24 mm. from lines of involution to venter, but they are easily separable by the eye. The earlier probably paraneanic substage dissected out from this was perfect and measured 2(>.5 mm. in diameter of the coil. The larger end of the volution in this was 15 mm. from line of involution to venter, and when the volution was about 11 mm. in same diameter the chevrons and costs and excessively faint longitudinal ridges began to appear. There were as many as three of these along the centran lateral aspect of the volution and .shorter but discontinuous ones arising from the chevrons. These could only be seen by careful and prolonged observation of the nacreous layer, which was preserved on one side. The sutures were less crowded than in the young one above described and favorable for obser- vations at diameter just noted. There were ten lobes in all, including one PLACENTICERATID.E. 227 on the line of involution. Six were on the lateral zone, one on the sharply defined umbilical shoulder, and three on the umbilical zone. The last sad- dle showed a distinct marginal lobe, the next saddle single, the succeeding saddles were also bifid and had entire outlines, the fourth had begun to show marginal digitations, and the remaining saddles were more or less deeply cut, having approximately the forms of the ephebic stage, but being, of course, much simpler. The outlines of all of them were free except those of third and fourth saddles and those of the third lateral lobe. The umbilical lobe is probably entire, as is the next lobe; the eighth is symmetricallv trifid, the next from its position on the umbilical shoulder is unsymmetrically trifid, the next lobe on the side is symmetrically trifid again. The remaining lobes show ephebic division already defined but simpler than in the adult, and the same is true also of the ventral lobe and saddle, and the bare spaces on the cast on either side of the venter would be as conspicuous as in the later stages if the sutures were as close together. One thing is noticeable in this specimen; the slightly younger sutures on the same volution are for a time slightly closer than the succeeding ones, owing to a temporary decrease in the rate of growth of the shell. This specimen had svitures quite diff"erent from the sutures of the small specimen above described, in which at the same age there were approximating and even decidedly overlapping outlines, as in the adult. The outlines themselves, however, were about the same in both specimens, so that the difterences were merely those of the slower, less vigorous growth of the forms as compared with that now being described. At the beginning of this volution, when the diameter from lines of involution to venter is 7 nun., the umbilical zone is just beginning to be formed. The ventral saddle at this time is just beginning to sliow digitations on its sides, and is broad and large with flat concavity across the venter. The first lateral saddle is distinctly trifid, the second and third laterals with club-shaped bases and almost entire, showing only the faintest possible trace of the median marginal lobe that divides tliem in the succeeding sutures; the fourth lateral has this marginal lobe more distinct, but still very small, and the remaining saddles are entire with somewhat flattened basal lines. The arras of the ventral lobe and the tops of the first and second and third laterals are unsymmetrically trifid, the fourtli lateral is just beginning 228 PSEUDOCERATITES OF THE CRETACEOUS. to have a median marginal division and is bifid, the remaining lobes being entire and very small and narrow. The trend of the sutures is about the same as in adults, but the bend at the fourth lateral saddle is more abrupt, the fourth lateral lobe being a scant one, about one-half the length of the third lateral. This proportion begins to alter soon after this, and approxi- mates to that of the adult before the end of this volution. The number of lobes and saddles is the same; they are simply smaller in size and more primitive in outline. A very slight amount of exposure acts upon these sutures and alters the outlines, destroying the marginal lobes and saddles. At this time, i. e., 7 mm. in diameter, the sutures are somewhat more primi- tive on the left than on the right side of the volution, an irregularity that subsequently becomes less noticeable. There is probably nothing abnormal in this, as it is rare in any animal to find the two sides exactly similar. The costse begin very early when the volution is about 7 mm. in diameter from lines of involution to ventei-. In the ananeanic substage, when the volution is 4 to 5 mm. in diameter, the ventral zone is channeled, as in later stages, and sensibly broader in proportion. The form of the sutures, etc., is the same, but the digitations are less noticeable. The first lateral saddle on the most perfect side of this volution is faintly trifid, all the remaining saddles are entire and club- shaped except the smaller ones beyond the fourth, which are now plainly seen as mere inflections of the outlines of the magnosellarian saddles. The arms of the ventral lobe are single, the first and second laterals are beginning to show trifid tops, while the third is broader and more club shaped, and shows four nearly equal marginal lobes just beginning to appear. The ventral saddle is broad with concave base, the dependent marginal saddles being absent. There were nine lobes at this stage, but the ninth on the line of involution was very minute. The next break exposed an earlier age in the ananeanic substage on the first quarter of the same volution. The venter had just become flattened and the edges of this zone are faintly crenulated on the cast, owing apparently to the presence of extremely fold-like cost* which cross the venter. These are so indefinite that they were perceived with difliculty. The sutures are extremely instructive. The ventral lobe is as deep and as broad as the ventral zone; the ventral saddle is very small and divided by a siphonal lobe. The sides of the first lateral saddles are PLACENTICERATID.E. 229 straight, and on the edges of the ventral zone the bases are entire and rounded. The tirst and second lateral lobes and the first, second, and third lateral saddles appear as inflections on the inner sides of the broad nepionic first lateral saddles. The third lateral lobes occupy the positions and are obviously the direct local representatives of the primitive primor- dialian lateral lobes. A large saddle, the primitive magnosellarian saddle, occupies the inner part of the sides and two minute marginal lobes and saddles are apparent on this. The first marginal saddle, the forerunner of the fourth and fifth saddles, is flat on the base and beginning to show an initial median marginal lobe; the future fourth lateral lobe, the inner saddle, has similar form but is still entire. This and the other specimens show that the great length of the third lateral lobes and the apical bend in the sutures and septa of adults are due to the retention of nepionic characters and that the great complication in the details of the outlines and the large number of lobes and saddles are based upon primitive neijionic outlines. This is also apparent in the internal double curvature of the septa, which are concave along the center and convex like those of most Ammonitinge only at the dorsal and ventral lobes. A fine young specimen. No. 18936, U. S. National Museum, Upper Missouri, enables me to add the following: Whole diameter is 55 mm., and the fourth volution is about completed. On the early part of this volution the sutures are the same as in the young specimen above described. The characteristic deeply cut saddles and lobes of the western fonn are already beginning to appear" and the first, second, and third lateral lobes have about the same proportions as in the adult, but the fourth lateral is only about half as long as the third lateral lobe. The sutures in this specimen are not so distinctly separated as in the young one at same age referred to, and are almost as closely intermingled as in the adult. The usual band free of sutures occurs on each side of the venter. On breaking down this specimen the sutures on the last quarter of the tlnrd volution were found to be more distinctly separated, the margins becoming simpler, but the peculiar bands free of sutures on either side of the venter are still present, and the species could hardly be mistaken even at this " The external shell is preserved in the umbilicus, but there are no tubercles, and venter is smooth on the cast of this part. The outer layer of shell of the last quarter of fourth volution is preserved and shows same markings as above described at about same age in young specimen from Nebraska. 230 PSEUDOCERATITES OF THE CRETACEOUS. earl}' stage on account of the much compressed wholly smooth volution and naiTOw conca\-e -s'enter with slightly elevated acute ridges on either side on the cast. At this age inner saddles assume a primitive rounded form with expanded base and one marginal central lobe; the inner lubes are trifid. Two specimens in the collection of the Boston Society of Natui-al History, collected by Prof. W. CI. Crosby, have the typical characters and form of P. whitfieldi and are devoid of tiibercles. The sutures were not very clearly made out. The matrix has the aspect of an arenaceous I limestone, color light brown. The largest specimen from Fort Collins, Colo., is l)-i5 mm. and the smaller one from El Paso County, Colo., 84 mm. in whole volution. One specimen in the collection of the Boston Society of Natural History reaches 265 mm. in diameter and has a concave ventral zone on both shell and cast at end of outer volution. There are excessively faint tubercles along the umbilical shoulders but no traces of them on the edges of the ventral zone, either on shell or cast. The shell on this specimen and on several others is sufficiently perfect to show that there are the following parts. An outer opaque probably porcellaneous part of several layers, next a middle part with more or less of luminous red coloration, also of several layers, and an inner part, also of several layers, with the usual iridescence of nacreous shell Two specimens from Loup Fork, Nebr., in the Museum of Comparative Zoology, show the typical large siphonal saddle with dependent marginal saddles of 'whitfieldi. One of them belongs to the parephel^ic stage of a shell having at the same time concave venter on both cast and shell with very faint tubercles, and the other and the two descnbed next below represent the gerontic stage of a shell of ver}- large size of the same species, with flattened venter on the cast and very faint concave zone on the shell, but no signs of tiibercles on this part. The umbilical shoulders were destroyed. In both of these specimens from Kansas the ventral branches of tirst lateral saddles did not reach the edges of the venter and the same smooth band appeared on either side of this part as in other forms of this group. I can not at present separate them frojn whitfiekJi upon the basis of their slight tuberculations, since faint tubercles are apt to be present at some stage even in typical forms of this species A fine specimen from Nebraska, diameter 228 ram , and covered with beautiful nacre, shows chevron markings and has concave ventral zone and faint, PLACENTICERATID.E. 231 ratlier uncertain indications of tubercles that may have existed on the outer shell, although the inner line on the umbilical shoulders is plainly shown on the nacre of the last volution. These last are obviously confined to this volution of the ephebic stage, since they are not present on the inner volutions, which are covered by the thick, opaque outer layer of the shell. This settles the fact that these tubercles may appear ver}- late in the life of this species. They are small and wide apart on this specimen when the volution from line of involution to the venter is 60 mm., and are not present on the external shell in that part of the same volution which is about a centimeter apicad across a break in the fossil. There are fine transverse wrinkles on the nacreous layer in the ventral zone of this shell. A large, much crushed fossil from Loup Fork, Nebr., also collected by Dr. Sternberg, is 215 mm. in diameter and has the external shell well preserved and as usual very thick, especially on the umbilical shoulders. Faint tubercles are present on the last volution and are also preserved on a remnant of shell belonging to a volution which has been broken away. Such small tubercles as these might be present on a shell and yet be absent on a cast. A fine specimen in the National Museum, with nacreous layer, from southern Colorado, and having typical sutures of the western form and also identical in other respects, has a diameter of 136 mm. and shows faint tubercles on the nacreous layer. The volution is 65 mm. in diameter from line of involution to venter, when the first tubercle appears. This specimen makes It possible to say definitely that these appear in the ephebic stage, probably metephebic substage. One specimen, from Black Hills region, in the collection of the Boston Society of Natural History, .shows faint tubercles on umbilical shoulders when the diameter is less than 100 mm., and there are faint but perfectly defined minute tubercles on either side of the venter. Another specimen in the same collection and from the same locality has a diameter of 305 mm. It is without living chamber and has the nacreous layer in part preserved. There are faint tubercles on the umbilical shoulders of the next imier and part of the outer volution. The sides have three obscure broad longi- tudmal folds or ridges in the gerontic stage. There are no tubercles on the edges of the ventral zone. This zone continues to be very faintly concave, even on the last part of the outer volution. The gerontic stage 232 PSEUDOCERATITES OF THE CRETACEOUS. beo-ins witli a slig-ht transverse constriction, after which the transverse diameters increase considerably and the vokition is stouter and larger. The largest specimen so far recorded is in the University Musemn in New Haven (locality, Bad Lands, South Dakota). This has been meas- ured b}^ Dr. C. E. Beecher, who also very courteously sent me a sketch and notes on its characteristics. The diameter of the entire fossil is 630 mm. (24f inches). The ventro-dorsal diameter of apei'ture from line of involu- tion to venter is 300 mm., and the transverse 150 mm., showing how much the volution has broadened in this extreme gerontic stage. The first quarter of outer volution has a flat venter 8 mm. wide, the edges rounded. The living chamber is perfect and occupies one-half of a volution, showing no decrease in length as compared with smaller specimens. There is, how- ever, the usual decrease in the amount of involution of the whole of the outer volution. The venter loses its flatness entirely on the second quarter of the outer volution and on central parts of living chamber, becomes rounded, and the sides then become gibbous at a short distance inside the venter, as is not uncommon in old age. There is a tendency to resume the form of syrtale and of its own earlier stages. Near the aperture the geron- tic flat zone noticed in other specimens returns upon the centran part of the venter, but the latter still remains rounded with the same gibbous out- line to the outer parts of the sides. The aperture, as desci'ibed in other specimens, has a short, broad rostrum and low, broad lateral crests. Locality: Nebraska; South Dakota; Colorado. Aye: Fort Pierre grouji, Upper Cretaceous. Placenticeras whitfieldi variety tuberculatum Hyatt. PI. XLVII, fig. 5. I have so far seen only three shells ft-om Bad Lands, South Dakota, having a very faint line of median lateral tubercles both on cast and shell, as well as minute denticles on the sides of the venter and tubercles on the umbilical shoulders. The two outer rows disappear at the end of the neanic stage, when the shell is about 80 mm. in diameter. These are obviously transitional to F. pseudoplacenta, but have much finer tuberculations and more complicated sutures. Locality: Bad Lauds, South Dakota. Age: Yort Pierre group. Upper Cretaceous. PLACENTICERATID^. 233 Placenticeras spillmani n. sp. Hyatt. PI. XL VII, figs. 6-8. This species is founded upon a fragment, No. 4, in the collection of the Academy of Sciences of Philadelphia; but this is so distinct from any species of Placenticeras known to me that I venture to describe it here. This was in same tray with three fragments of Sphenodiscus labeled "Spill- man Coll. Loc. Mi.ssissippi." The estimated diameter of the volution is 80 mm.; tiie actual ventro- dorsal diameter measured along the exposed septum from dorsal lobe to ventral lobe is 48 mm.; and actual transverse diameter is about 40 mm. through the dorsal lobe. It has, therefore, a much stouter volution at the same age than its near allies, placenta or stantoni, and the venter is broad in proportion, being 9 mm in width, flat, and with low tubercles on either side about 14 mm. apart. The fragment is onlj- the cast of the outer parts of two living chambers, and whether there were internal rows of tubercles could not be determined, but the sides have the flattened aspect of species that do not habitually have a median lateral row of tubercles. The sutures are closely similar to those of syrtale; they have broad, rather short, solid saddles, with short marginal saddles, the lobes narrow and broad, only at the apical ends. The outer part of the septum is more deeply concave than in placenta and the lobes and saddles are less complex in outline. There is a cast of one chamber in the collection of Yale University, said to be from Burlington, N. J., with a similar broad venter, that may be the young of this species. The dorso-ventral diameter measured in same way as above is 24 mm., and transverse diameter is about 18 mm. There is aLso a cast from Musselshell Creek, Idaho, having a very broad venter. This belonged to a much older and larger .shell with very different sutures. Locality: Burlington, N. J.; Mississippi. Placenticeras ? telifer (Morton). Ammonites telifer Morton, 1834, Synop. Organic Reniain.s, pi. 2. Ammonites (Placenticeras) telifer Whitfield, 1892, Mon. U. S. Geol. Survey. Vol. XVIIl, pi. 41. After examining the fragments of this species in the collection of the Academy of Sciences, Philadelphia, I am unable to determine with 234 PSEUDOCERATITES OF THE CRETACEOUS. certainty whethei- this is a species of this genus or not, and the details of the sutures, so far as my hasty examination went, were too imperfect to enable me to make a reasonable guess with regard to their affinities. Locality: New Jersey. Age: Upper Cretaceous. Placenticeras ? FALLAX Castillo and Aguilera Placenticeras ? fall ax Castillo aud Aguilera, 1895, Bol. Codi. geol. de Mexico, No. I, p. 17, pi. 9. This species is here mentioned because it is likel}- to be quoted as a species of this genus, whereas both the remarks of the authors and tlie figures show that it should be quoted as probably not a membei- of this genus. The authors consider the sutures as placenticeran, but xerj rightly regard the form as more like that of Phylloceras. I have not as yet seen a specimen of this genus that has such a rounded volution even in the gerontic stage, and this Mexican specimen was only 104 mm. in diameter. Locality: Mexico. Age: Lower Cretaceous 1 Placenticeras ebrayi (de Loriol). Amaltheus ehray! de Loriol, 1882, Mem. Soc. Pal. kSuisse, Vol. IX. PI. I. Placenticems ehrayi Kossmat, 1895, Beitr. Pal. und Geol. Oesterreicli-Unganis uud des Orients, Vol. IX, p. 170. This figure shows a large and aged specimen of 250 mm. in diameter. The anagerontic substage is given ujjou the first part of the outer volution, and during this time the venter remains flattened and has large alternating tubercles of the usual elongated form on either side, but the edges of this zone are not sinuous. There are fold-like single cost* appearing in this substag'e, and these are prominent, but have no tubercles if the views are correct. These single folds are continued in the metagerontic substage when the ventral line of tubercles disappear and three lines of lateral tubercles appear for the first time on the costa?. In the paragerontic substage these tubercles disappear, first the outer, then the inner lines, and then the central line. The folds also tend to disappear aud the venter is seen to be completely rounded and smooth in this substage and the involu- tion has become considerably diminished, judging from the aspect of the PLACENTICERATID.E. 235 umbilicus. The gerontic tubercles, together witli the ventral line of tubercles, make u]) four rows, one more than appears in any other shell of this genus. The sutures were observed only in the anagerontic substage, but they are distinctly separated and have obviously not lost then- ephebic characters. There may be but two secondary laterals derived from the primitive first lateral saddle, or there may be three ; one can not tell with exactitude from the drawings and descriptions. The general aspect of this shell is in favor of association with the species of Placenticeras, but the extra line of tubercles in the old, the fold-like, almost straight costse, and the possibility that there ai'e only two secondary saddles, the first and second laterals, niake the generic reference doubtful. The outlines of these sutures remind one strongly of P. warthi Kossmat, and in this species there is also the same difficultv in making out whether the first lateral is single or double. The ventral lobe is deep and narrow, as in P. uhligi, but the siphonal saddle is small. The shell is apjjarently smooth in the ephebic stage, as in warthi, etc. Age: Gault of Cosne. Placenticeeas warthi Kossmat. Aimaonite« orhignyanKH Stoliczkii. 1860, Pal. liulica. Vol. I, pi. 48, fig. 2. Placenticet'ttii imrthi Kossmat, 1895, Beitr. Pal. und Cieol. Oesterreich-Ungarns und des Orients. Vol. IX, pi. 20, fig. 8. This species is, as stated by Kossmat, quite distinct either from orhig- nyanus of Geinitz, or syrtalis, var. orhignyanus of Schliiter. Kossmat's text clearly states these distinctions, but he gives both of these names in his synonymy as in part belonging to this species, and on this fact we differ. The young as figured in section by Stoliczka has a very broad venter in the ananeanic substage and the broad venter is retained throughout the neanic stage. The sutures are exceptional, the ventral saddle distinct from any other species of this genus, and there are so slight differences between the princi- pal lateral saddles and the auxiliaries that one can not, according to Kossmat's figures, draw a definite line between the auxiliaries and the principal saddles. Kossmat counts the two arms of the first lateral as two saddles, but describes these as having arisen from division of the firsf 236 PSEUDOCERATITES OF THE CRETACEOUS. lateral, and his figure shows this. He consequently considers the si)ecies as having four principal lateral saddles, whereas they should Ije counted as three. Stoliczka's figure of the older specimen in his Fossil Cephalopoda of Cretaceous Rocks of Southern India also shows distinctly the three princi- pal saddles. Kossmat considers this identical with the American P. syrtale, but, as has been noted elsewhere, P. tamulicum, and especially schluteri, are more like the former. The absence of all except the ventral line of tuber- cles and the broad, fold-like costse, broad venter, and stout whorls are as peculiar as the sutures in warthi. In the ragged aspect of the sutm-es and broad, flat venter, this s^jecies has some resemblance to P. stantoni of the Colorado group. This favors the view that this species occurs in India somewhat earlier (in the lower Utatur group, which is placed by Kossmat in the Cenomanian) than its representative in this country. This evidence is in favor of the view stated by Stanton and others that the Colorado is the equivalent of the Turonian. Age: Cenomanian. Placenticeras memoria-schloenbachi Laube and Bruder. Placenticeras m&m.oria-schloe'nbacld Laube and Bruder, 1887. Palfeontogr. , Vol. XXXIII, pi. 23. This species has a diameter of 198 mm.; it is smooth witli the excep- tion of a single inner row of small tubercles on the umbilical shoulder. The umbilical zone is well shown in figure, and the ventral zone very nar- row and smooth on the cast. The parts of two sutui'es shown haA-e very simple outlines and are wide apart even in what is evidently the parephebic or anagerontic stage of this species. The outlines are probably more or less worn and have lost their digi- tations in part, but could not in any event probably have been as closely approximated as in species like placenta or whitfieldi. Laube and Bruder consider that the sutures are similar to those of Placenticeras requieniamim (d'Orbigny, Ten-. Jurass., pi. 93, fig. 4), but this species does not belong to this genus. Age: Turonian. PLACENTICERATID^. 237 Placenticeras depressum u. sp. Hyatt. I^acenticeras syrtaJe Grossouvre (jjars), 1893, Ammonites Craie superieure, p. 128, pi. 6, fig. 2 oul}', and pi. 7, fig, 1. Ammonites syrtalis Schluter (pars), 1871, Palaeontogr. , Vol. XXI, pi. 14, figs. 9 and 10 only. This French and German species is undoubtedly a very close ally of gnadahqm and is called variety guadalupee by both authors, who suppose it to be identical with the American species of the same name. The latter, however, has not the costse in the young shown in the umbilicus as figured by Grossouvre on pi. 7, and the inner nodes in the American form are on the umbilical shoulder at all stages, the umbilici being deeper and the volution thicker or stouter in proportion This species also includes Grossouvre's variety quadratum. The saddles are more deeply undercut and outlines of both lobes and saddles more complex. They are, however, very closely representative species. Schliiter's figure shows the impression of a keel in the impressed zone of the fragment of an outer volution, but this is probably either accidental or a mistake in the figure, judging from the description. The obvious excellence of Grossou\Te's work and figures enables one to see clearly the relations of these forms, and he describes them as varieties. We difter simply in our estimate of their relative imjior- tance, he preferring to call them varieties, and I to name them as distinct species in accordance with the methods adopted in this and other papers. Age: Lower Senonian (Santonian). Placenticeras grossouvrei u. sp. Hyatt. PlacenticeraK syrtale (pars) Grossouvre, 1893, Ammonites Craie superieure, pi. 5, fig. 32; p. 16, fig. 1 (no others). The French form has no corresponding' representative now known ni this covmtry. The young, if it be the young, figured on pi. 5, is costated like the gerontic stage oi polyopsis of Dujardin, but it also has a prominent, closely set row of tubercles on either side of the narrow concave venter. The large fossil figured on pi. 6 has an umbilicus so very different that if it belonged to almost any other genus one would say at once it could not be the same. In this genus, however, the young are so compressed and distinct that no safe inference can be made from figures alone. This 238 PSEUDOCEKATITES OF THE CRETACEOUS. specimen is certainly in the gerontic stage, with the median lateral row of tnbercles already on the borders of the venter. The ventral rows shown in fig. 3 of pi. 5 have disappeared entirely, and the venter is smooth and flat and very broad, the tubercles nearly opposite. The inner row of nodes begins to recede from the line of involution very early and gradually approximates to the outer row. On the last quarter these tubercles again begin to apjjroach the umbilical shoulders, increasing their distance from the outer line — a movement not ]jaralleled in any American form I have as yet seen. Aye: Lower Senonian (Santonian). Placenticeras iNCisuM n. sp. Hyatt. Placentlcefras syrtale (pars) Grossouvre, 1893, Ammonites Craie superieure, pi. 8, fig-. 1 (no others). In this form the volution is described and figured as compressed and smooth until a late stage. The specimen is in the jiarephebic substage on the first quarter of the outer volution; i. e., the median lateral line of tubercles is close to the ventral line. The venter is, however, still concave, narrow, and tuberculated. On the second quarter the venter broadens to these lines of tubercles, the ventral ones disappear, the inner line ()f large nodes appears first at the center of the lateral zone.? and rapidly approximates to the outer lines, being joined to them by costse. There are only five of these nodes, and while the third and fourth are nearest to the venter, the fifth is set somewhat farther away inwardly, thus nidicating, as in i/rossouvrei, the same tendency of the nodes to return inwardly in extreme age. The peculiar broad, concave venter of the paragerontic substage is also akin to the aspect of the venter in an earlier substage in ffrossouvrei, but is a great exaggeration of this tendency, and occurs after the venter has become convex in the anagerontic substage, as is shown on the lower outline of fig. lb. These figures are so fine that these observations are made upon their authority, and show a great difi'erence between these and related American forms. Grossouvre's reference of this variety to P. milleri of Haiier allows more latitude for variation than is given in this memoir. Jlilleri has only one row of tuVjercles, and the form of the venter is distinct. Age : Senonian. PLACENTICERATID.E. 239 Placenticeras milleri (Hauer). Ammonites milJeri Hauer, 1866, Sitzungsbei'. K. Akad. Wiss., Wien, LlII, p. 3(14. pi. 2. This species from Steirmark is quite distinct from mw of the French forms described by Grossouvre, but it may be identical with some of the German forms ah-eady described having but one row of tubercles in an advanced stage of development. It has smooth sides, with only one row of tubercles on the outer volution, and apparently also in the earlier stages, as figured and described by Hauex". As stated by that author, it is very like bidorsatus, except that it has a convex and moderately broad venter. This last character also, as well as the peciiliar form of the nodes on the edges of the venter and absence of inner lines of tubercles, separates it from Grossouvre's species. Hauer had specimens from 2 to 3 J inches in diameter. Age : Senonian. Placenticeras schluteri n. sp. Hyatt. Ammonites ayrtali-s var. polyopsis Schliiter, 1872, Palseontogr., Vol. XXI, pi. 1-4, figs. 1-2. This species has ornaments very similar to those oi polyopsis Dujardin, but these are quite distinct and peculiar in their ontogeny. The ephebic stage has two rows of large lateral tubercles, as well as ventral rows, and according to Schliiter's figures and descriptions the inner row in the anagerontic substage recedes outwardly, becoming approximate to the second outer row. The venter at the same time changes, becoming rounded and broader, but the ventral tubercles are still present. These figures are similar to the American syrtale, but differ in being less involute and in the wider removal of the inner row of tubercles from the umbilical shoulders and the elliptical section of the gerontic stage. In syrtale this section is distinctly subtriangular and more compressed in the same metagerontic substage. Age: Lower Senonian. 240 PSEUDOCERATITES OF THE CRETACEOUS. Placenticeras orbignyanum (Geinitz). Ammonites vihrayeanm Geinitz, 1843, Verst. v. Kieslin^walde, PI. I. fig. 8. Avirnovites oi'hignyamm GiQimtz^ 1850, Quadersand. in Deiitschl.. pi. 14. Avmwnites orhignyanus Drescher, 186-S, Zeitschr. Deutsch. geol. Gesell., Vol. XV, %. 8. Ammonitea orhignyanus Fi'itsch and Schlonbach, 1S72, Ceph. bohni. Kreide, pi. 10, figs. 4, 5. Ammonites orhignyanus Geinitz, 1875, EDithalgeb. in Sachsen, pi. 36. Ptacent. yritseki Grossouvre, 1893, Ammonites Craie superieure, pi. 5, figs. 1, 2. This species has fold-like costse and broad venters in the young, as figured by Fritsch and Schlonbach and by Geinitz in his Quadersandstein- gebirge. One can not say anything definitely from the figure given in the first publication under name of vihrayeanus. The figure in Elbthalgebirge also apj^ears to be the young of this same species; consequently Drescher's figure of the suture quoted above must also belong to this species and serves to correct the conventional figure given in Quadersandsteingebirge. There are three principal saddles, as in other species of this genus. Grossouvre's figures are excellent and give clear ideas of this species. The broad, smooth, convex venter of what is j^robably the gerontic stage, and the voung, both having costa? like the figures in the Quadersandstein- gebirge, appear to show that the French and German forms are identical. The sutures as figured are diff'erent, but this may be due to the poor drafting of the figures in the Quadersandsteingebirge and in the Zeitschrift l)y Drescher. Age: Lower Senonian. Placenticeras polyopsis (Dujardin). Ammonites polyojysis TyxxisivAin, 1837, Mem. 8oc. geol. France, No. 2, pi. 4. This species has a form similar to pseiidorhignyamim, but only in old age, the ephebic stage being smooth. The flattening of the venter in the gerontic stage is a transforaiation that may occur in any species of this and other genera at the same age and can not be considered to indicate specific identitv. The ornaments are altogether different. The tubercles of the outer row are more or less connected with the inner row by indistinct, more or less bifurcated, costaj, and the inner row does not change place with age. The ventral tubercles are larger and more widely separated than in PLACENTICERATID^E. 241 schliiferi, and all the tubercles and costse occur onlv in old age, according to the figures, Avhereas in the latter they are present in adults as well as in the gerontic stage. Age: Lower Senonian. Placenticeras crassatum n. sp. Hyatt. Ammfmites syrtalis var. orbignynnm Schliiter (pars), 1872, Palseontogr. , Vol. XXI, pi. 14, figs. 4-7, fig. 3? (no others). This species differs from schliiteri, being more compressed. The recession outwardly on the inner row of tubercles does not take place. The inner row of tubercles disappears in what is probably the anagerontic substage, and in this also fold-like costa^ are develo^jed. The venter remains flattened, the sides flat, and the ventral tubercles are still well developed in this substage. Affe: Lower Senonian. Placenticeeas tamttlicum (Blanford). Avwionites tamulicus Blanfonl. 1863, Mem. Geol Surv. Iiidiii. Vol. IV, p. 118. Ammonites guadalupse, Stoliczka, 1866, Pal. Indica, Vol. I, pi. 47, and pi. 48, tig. 1. Placenticet'ds tanodicuiii Kossmat, 1895, Beitr. Pal. mid Geol. Oesterreich-Uiigarns und des Orients, Vol. IX, pi. 22, figs. 1 a-c. The neanic stage of this Indian species is figured by Kt)ssmat, and this, together with the figures by Stoliczka, shows that this shell had a more compressed form, flatter sides, narrower ventral zone, and difterent sutures iu the adult and less prominent and less distinct costations than the gibbous-sided form, also included in this species by Stoliczka in Paleonto- logia Indica and figured, pi. 47, fig. 2, sutures being also given, fig. 2a. There are considerable variations in the shapes of the saddles, between the last figure and those of tamuUcum {giiadahipce) on jjl. 48, fig 1, which can hardly be accounted for by diff'erences of age in the specimens. It is diffi- cult of course to say to which of the two forms the large specimen on pi. 47, fig. 1, may belong, and any attempt to separate them under diiferent names would not be advisable. This last figure, 183 mm. in diameter, ia in the gerontic stage and shows a second external row of nodes of large size and the inner row increasing greatly in size to blunt nodes on the last part of this volution. None of these authors mentions any rouuding-off" of MON XLIV — 08 16 242 PS-EUDOCEKATITES OF THE CRETACEOUS. tliu venter in old age, and apparently the venter retains its epheljic char- acters in this old specimen. I can not join Kossmat in considering syrtale of Schliiter as identical with this species. The American syrtale shows old age at a smaller size than in tamnUcum, and the nodes and spines are much larger and last longer, especially the median lateral row, but it is much closer to this species than to any other European form except schliiteri. The more compressed foi'm of pi. 48 has the external characters of the American lenticulare as figured by Meek, but the sutures are quite distinct. Age : Lower Senonian. Placenticeras pseudorbignyanum n. sp. Hyatt. Ammo/iitcs >oly ops is Schliiter, 1867, Ammoneen norddeutsch. Senon., pi. 4. Ammonites hidorsatus Schliiter, 1872, Pala;ontogr., Vol. XXI, pi. 1.5, ligs. 6-8. This species is very peculiar, having a well-defined gerontic stage with a row of lateral tubercles" set well out near the venter and becoming- nodose or prominent. The shell in the ephebic stage is smooth and compressed, the venter is extremely narrow and channeled, and there are « These are in no way comparable with ventral lines of tubercles as they occur in Placenticeras, being on the sides and near, but not on, the edges of the venter. 244 PSEUDOCERATITES OF THE CRETACEOUS. smooth continuous ridges on either side that can be compared with those of Eugonoceratidff. The differences between the shell figured by Schliiter and the hidorsatuni of Roemer are so well shown in the drawing given by the latter that there can be but little doubt they are different species. The sutures are not distinct generically from those of Placenticeras, and would place the species in that genus if the characters of the shell were not so different. Locality: Westphalia. A(/e: Lower Senonian. Incertae sedis. STYRACOCERAS " n. gen. Hyatt. Ammonites balduri of Keyserling, the type and only known species of this genus, can not be associated with any s]iecies known to have same number of principal lateral saddles, because the external characters differ from those of any species known to me. The resemblances in the sutures are certainly closer to Platylenticeras heteropleurmn than to any other species, if Keyserling's drawings and Neumayr's observations are correct. The suture has two broad principal lateral saddles, the first and second, or else these maj- be reckoned, as in others of this group, as one saddle divided into two branches. Until the young are known, this can not be definitely decided. (See Platylenticeras^ Styracoceras balduri (Keyserling). Aiiiiiionites'baldiiri Keyserling, 1S46. Petschora-Land. pi. m, tig. 2. The young, as figured by Keyserling, has a channel on the venter in the neanic stage after passing through a substage with an acute venter. This figure may have been taken from a partly crushed fossil. So far as known, the replacement of an acute condition of the venter by a furrow is exceptional and requires more proof than a single drawing. Neumayr obtained the originals of Keyserling's description and studied them, but his attention was not apparently attracted to this fact, and he did not break down any of the fossils to investigate the young. He redescribed, but, unluckily, did not have them redrawn, and did not state whether the 1^ 2TVpa^, spike on the inner end of a spear. PLACENTICERATID.E. 245 smallest fossil, about 10 mm. in diameter, was exactly represented in Key- serling's fig'm'e which shows the acute venter. Neumayr" does, however, state clearly that the venter becomes furrowed at 15 mm. in diameter, and that this furrow is succeeded by a stage with a rounded venter which pre- ceded the incoming of a stage with a slightly convex venter and distinct ventro-lateral angles, and that this precedes a stage with distinct keel devel- oped upon the elevated venter, and tubercles developed upon the costae internally and at their terminations on the ventro-lateral angles. Such an extraordinary succession of transformations is irreconcilable with those of the ontogeny of any group known to the author. The resemblances of the sutures are, therefore, not sufficient to place the genus in the same group with Plutylenticeras, from which it differs in every other respect. Neumayr's view of the affinities of this genus for the Amaltheidse is not sustained by anything except the general similarity of the external aspect of adults, which is probably due to parallelism, and the same is true of its supposed affinities for CarcUoceras. The characteristics of form and ornamentation supposed to be so similar have obviously arisen from entirely distinct modes of develo^jment, and these genera are not even as closely related to each other as to Styracoceras. Age: Neocomian. aUeber Amalth. balduri Keyserl. u. d. Gattung Cardioceras. Neues Jahrb. fiir Min., GeoL, and Pal., 1886, 1, p. 95. BIBLIOGRAPHY. Batle, E., and H. Coquand. Memoire sur les fossiles secondaires recueillis dans le Chili par M. 1. Domeyko et sur les terrains auxquels ils appartiennent: Mem. Soc. geol. France, 2d series, Vol. IV. 1851. Batle, E., and R. Zeiller. Explication de la Carte geologique de la France, Vol. IV, Atlas. Paris, 1878. BiNCKHORST, J. J. T. VAN. Monographie des Gasteropodes et des Cephalopodes de la Craie superieure du Limbourg. Brussels and Leipzig, 1873. Blanford. H. F. Cretaceous rocks of the South Arcot and Trichinopoly districts: Mem. Geol. Surv. India, Vol. IV, Pt. I. 1863. BoHM, J. Ueber Ammonites pedernalis v. Buch: Zeitschr. Deutsch. geol. Gesell- schaft, Vol. L, pp. 183-201. 1898. Buch, L. von. Ueber Cei-atiten: Abhandl. K. Akad. Wiss. zu Berlin. 1848, pp. l-30c. 1850. BucKMANN, S. S. A monograph on the Inferior Oolite ammonites of the British Islands. Palffiontographical Society. 1887-1896. Castillo, Antonio del, and Jose G. Aguilera. Fauna fosil de la Sierra de Catorce, San Luis Potosi: Boletin de la Comision geologica de Mexico, No. 1. 1896. Choffat, Paul. Recueil d'etudes paleontologiques sur la faune cretacique du Por- tugal. Vol. I, Especes nouvelles ou peu connues. 2d series. Les Ammonees de Bellasieu. des couches a Neolobites Vibrayeanus du Turonieii et du Senouian. Lisbon, 1898. Conrad, T. A. 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Report on several fossil niultilocular shells from the State of Dela- ware, with observations on a second specimen of the new fossil genus Euryp- terus: Ann. New York Lyceum Nat. Hist., Vol. II, pp. 273-279. New York, 1828. DouTiLL^, H. Sur la classification des Ceratites de la Craie: Bull. Soc. geol. France, 3d series, Vol. XVIII, pp. 275-292. 1S90. Sur le Tissotia tissoti: Bull. Soc. geol. France. 3d series. Vol. XIX. pp. 499-503. Paris, 1891. Drescher, R Ueber die Kreide-Bildungen der Gegend von Lowenberg: Zeitschr. Deutsch. geol. GeselL, Vol. XV. pp. 291-366. 1863. DuJAKDiN, Felix. Sur les couches du sol en Touraine et description des coquilles de la Craie et des Falons: Mem. Soc. geol. France, 1st series, Vol. II, pp. 211- 315. 1837. DuNKER, W. Ueber Ammonites gervilianus d'Orbignv aus dem norddeutschen Hils- thone: Palseontographica. Vol. I, pp. 324, 325. 1851. Fallot, E. Etude geologique sur les etages moyens et superieurs du tei'rain Cre- tace du sud-est de la France: Annales des sciences geologiques, Vol. XVIII. 1885. Fischer, Pall. Manuel de Conchyliologie et de Paleontologie conchyliologiijue. Paris, 1887. Forbes, E. Report on the fossil invertebrata from southern India: Trans. Geol. Soc. Lond., 2d series, Vol. VII, pp. 97-17-1. London, 1845. Fritsch, a., and U. Schlonbach. Cephalopodeu der bohmischen Kreideformation. Prag, 1872. Gabb, W. M. Description of Cretaceous fossils from Mexico: California Geologi- cal Survej-, Paleontology of California, Vol. II, pp. 255-276. 1869. Description of a collection of fossils made by Dr. Raimondi in Peru : .lnur. Acad. Nat. Sci. Philadelphia, 2d series. Vol. VIII, pp. 263-336. Philadelphia, 1877. Geinitz, H. B. Das Quadersandsteingebirge oder Kreidegebirge in Deutschland. Freiburg, 1850. • Das Elbthalgebirge in Sachsen: Palwontographica. Vol. XX. Cassel, 1871-1875. Die Versteinerungen von Kieslingswalda im Glatzischen, und Nachtrag zur Characteristik des siichsisch-bohmischen Kreidegebirges. Dresden and Leip- zig, 1843. Gerhardt, K. Beitrag zur Kenntniss der Kreideformation in Venezuela und Peru. — Beitrag zur Kenntniss der Kreideformation in Columbien: Neues Jahrb. fiir Min.. Geol., und Pal.. Beilage-Band XI, pp. 65-208. 1897-98. 248 PSEUDOCERATITES OF THE CRETACEOUS. Grossodvre, a. de. Les Aiiinionite;? de la Craie superieure: Mem. pour servir a rexplication de la carte geol. detaillee de la France. Paris, 1893. Hamlin, Charles E. Results of an examination of Syrian moUuscan fossils, chieflj- from the ran|je of Mount Lebanon: Mem. Mus. Comp. Zoology, Vol. X, No. 3, pp. 1-68. 1884. Hauer, F. von. Neue Cephalopoden aus den Gosaugebilden der Alpen: Sitzungsb. K. Akad. Wiss., Wien, Vol. LIII, Abth. 1, pp. 30()-3U8. 1866. Hermite, H. Etudes geologiques sur les lies Baleares (Majorque et Minorque). Paris, 1879. Hyatt, A. Report on the Cretaceous fossils from Maroim: Geology and Physical Geography of Brazil, by C. F. Hartt, pp. 385-393. Boston, 1870. The Jurassic and Cretaceous Ammonites collected in South America bj' Prof. James Orton, with an appendix upon the Cretaceous Ammonites of Prof. Hartt's collection : Proc. Boston Soc. Nat. Hist. , Vol. XVII, pp. 365-378. 1875. Bioplastology and related branches of biologic research : Proc. Boston Soc. Nat. Hist., Vol. XXVI, pp. .59-12.5. 1893. Cephalopoda. Text-book of Paleontology, by Karl A. von Zittel. Vol. I. Pt. II, pp. 502-592. London and New York, 1900. JiMBO, K. Beitriige zur Kenntniss der Fauna der Kreideformation von Hokkaido: Pala^ont. Abhandl. herausg. von Dames u. Kayser, new series. Vol. II, Pt. II. Jena, 189-4. Keyserling, a. Wissenschaftliche Beobachtungen auf einer Reise in das Pet- schora-Land im Jahre 1S43. St. Petersburg, 1846. KossMAT, Franz. Untersuchungen iiber die siklindische Kreideformation: Beitr. Pal. Geol. Oesterreicb-Uugarns und des Orients, Vol. IX, Pts. Ill und IV; Vol. XI, Pts. I und III. 1895-1897. Laube, C. C, and G. Bkuder. Ammoniten der bohmischen Kreide: Palfeontogra- phica, Vol. XXXIII, pis. 4-6. Stuttgart, 1887. LoRiOL, p. DE. Etudes sur la faune des couches du Gault de Cosne: Mem. Soc. Pal. Suisse, Vol. IX. 1882. Meek, F. B. A report on the invertebrate Cretaceous and Tertiary fossils of the Upper Missouri country: Mon. U. S. Geol. Surv. Terr., Vol. IX. Wash- ington, 1876. Morton, S. G. Synopsis of the organic remains of the Cretaceous group of the United States. Philadelphia, 1834. Neumayr, M. Die Ammoniten der Kreide und die S3^stematik der Ammonitiden: Zeitschr. Deutsch. geol. Gesell., Vol. XXVII, pp. 854-942. 1875. Ueber Kreideammoniten: Sitzungsber. K. Akad. Wiss., Wien, Vol. LXXI, pp. 639-693. 1875. Neumayr, M., and V. Uhlig. Ueber Ammoniten aus den Hilsbildungen Nord- deutschlands: Palfeontographica, Vol. XXVII, pp. 129-203. Cassel, 1881. NiCK.Lt;s, R. Contributions a la paleontologie du sud-est de TEspagne: Mem. Soc. g4oI. France, Paleontologie, No. 4. 1890-1894. BIBLIOGRAPHY. 249 NoETLiNG. Fritz. Fauna of the Upper Cretaceous (Maestrichtien) beds of the Mari Hills: Pal. Indica. Ser. XVI, Fauna of Baluchistan, Vol. 1, pt. 3. Calcutta, ls!t7. Oppel, a. Palaeontologische Mittheilungen aus dem Museum des Baierischen Staates. Stuttgart. 1S60-1S6.5. D OrbKtN'y. a. Paleontologie fran9aise: Description des animaux invertebres. Terrain Cretace. Vol. I, Cephalopodes. Paris, 1840, 1841. Voyage dans I'Amerique meridionale. Vol. Ill, Pt. IV, Paleontologie. 1842. Prodrome de Paleontologie stratigraphique univorselle des animaux mollusques et rayonnes. Paris, 1850-1852. OwEX, D. D. Description of new and imperfectl}' known genera and species of organic remains, collected during the geological surveys of Wisconsin, Iowa, and Minnesota: Report of a geological sui-vej' of Wisconsin, Iowa, and Minnesota, and incidentally a portion of Nebraska Territory, pp. 571-587. Philadelphia, 1852. Peron, a. Exploration scientifique de la Tunisie: Description des Mollusques fossiles des terrains Cretaces de la region sud des hauts-plateaux de la Tunisie. Paris, 1890, 1891. Les Ammonites du Cretace superieur de TAlgerie: Mem. Soc. geol. France, Paleontologie, Vols. VI and VII, No. 17. 1896, 1897. Pictet, F. J., and G. Campiche. Description des fossiles du terrain Cretace des environs de Sainte-Croix. Materiaux pour la paleontologie Suisse, Ser. II- VI. 1858-1872. QuENSTEDT, F. A. Die Ammoniten des schwiibischen Jui'a. Stuttgart, 1885-1888. Redtenbacher, A. Die Cephalopodenfauna der Gosauschichten in den nordostlichen Alpen: Abhandl. K. K. geol. Reichsanstalt, Vol. V, pp. 91-140. Wien, 1873. Roemer, Ferdinand. Die Kreidebildungen von Texas und ihre organischen Einschliisse. Bonn, 1852. Roemer, F. A. DieVersteinerungendesnorddeutschenKreidegebirges. Hannover, 1841. Sayn, G. Description des Ammonitides du Barremien du Djebel-Ouach (pres Constantine). Annales de la Societe d'agriculture de Lyon, 6th series. Vol. Ill, pp. 135-208. 1890. SowERBY, J. Mineral conchology of Great Britain. 1812-1830. ScHLUTER, C. Beitrag zur Kenntniss der jiingsten Ammoneen a. d. norddeutschen Senon. Bonn, 1867. Cephalopoden der oberen deutschen Kreide: Palseontographica, Vol. XXI, XXIV. Cassel, 1871-1876. Sharpe, Daniel. Description of the fossil remains of Mollusca found in the Chalk of England. Palseontographical Society, 1853-1856. Shumard, B. F. Descriptions of new Cretaceous fossils from Texas: Trans. St. Louis Acad. Sci., Vol. I, pp. 590-610. 1859. 250 PSEUDOCERATITES OF THE CRETACEOUS. Smith, James Perkin. The development and phjdogeny of Placenticeras: Proc. Cal. Acad. Sci., 3d series, Geology, Vol. 1, No. 7, pp. 181-240. San Fran- cisco, 1900. Stanton, T. W. The Colorado formation and its invertebrate fauna: Bull. U. S. Geol. Survey No. 106. Washington, 189-t. Steinmann, G. Tithon und Kreide in den peruanischen Anden: Neues Jahrl>. fi'ir Min.. Geol., und Pal., 1881, Vol. II, pp. 131-153. 1881. Stoliczka, F. and H. F. Blanford. Fossil Cephalopoda of the Cretaceous Rocks of southern India: Mem. Geol. Surv. India, Palteontologia Indica, Series I and III. 1861-1866. Struckmann, C. Die Grenzschichten zwischen Hilsthon und Weaiden bei Borsing- hausen am Deister: Jahrb. K. Preuss. geol. Landesanstait und Bergukademie, pt. 3, pp. 5.5-79. Berlin, 1S89. THiOLLii:RE, V. Note sur une nouvelle espece d'Ammonite provenant des gres verts superieurs du departement de la Drome: Ann. Soc. d' Agriculture de Lyon, 1st series, Vol. XI. 1848. Tuomet, M. Description of some new fossils from the Cretaceous rocks of the Southern States: Proc. Acad. Nat. Sci. Philadelphia, Vol. VII, pp. 167-172. Philadelphia, 1856. Uhlig, V. Die Cephalopoden der Wernsdorfer Schichten: Denkschr. K. Akad. Wiss., Wien. Vol. XLVl. 1883. Ueber die Cephalopodeufauna der teschener und grodischter Schichten: Denkschr. K. Akad. Wiss., AVien, Vol. LXXII. 1901. White, Charles A. Report upon the invertebrate fossils collected in portions of Nevada, Utah, Colorado, New Mexico, and Arizona, hj pai'ties of the expedi- tions of 1871, 1872, 1873, and 1874: U. S. Geog. and Geol. Surv. W. of the One hundredth Meridian, Vol. IW Paleontology, pt. 1. Washington, 1876. Contribution to the Paleontology of Brazil; comprising descriptions of Cretaceous invertebrate fossils, mainly from the provinces of Sergipe. Pernam- buco, Para, and Bahia: Archivos do Museu Nacional do Rio de Janeiro. Vol. VII. 1888. Whitfield, R. P. Gasteropoda and Cephalopoda of the Raritan clays and Green- sand marls of New Jersey: Mon. U. S. Geol. Survey.Vol. XVIll. Washington. 1892. ZiTTEL, Karl A. von. Handbuch der Palwontologie. Abtheil. I. Pala?ozoologie, Bd. II. 1881-1885. PLATES. 251 PLATE I. 253 PLATE I. MOJSISOVICSIA, BUCHICERAS. ROEMEROCERAS. Page. Figs. 1-3. Mojsisoincsia durfeldi Steinniann 2.5 Specimens from Pariatambo, Peru; Albian? (after Steinmann). Figs. 4-9. BucMceras hilohatum Hyatt 27 Figs. 4, 5. Natural size. 6. Enlarged, showing cost^ie and aspect of center. 7. Front view of center of fig. 6. 8. Suture from outer volution, part broken off in fig. 6, X 3. 9. Suture of young X 10 when the costje begin to appear. Cachiyacu, Peru; Upper Cretaceous; my collection. Figs. 10-14. Roemeroceras nyriaciforme Hyatt 31 Fig. 10. Aged specimen. 11. Suture of same. 12. Younger stage of another specimen, all natural size. 13. Suture of same, right side, X 3. 14. Suture of same, left side, X 3. Cajamarca, Peru; Upper Cretaceous; my collection. Fig. 1.5. Roenieroceras aUenuiitiim ( Hyatt) 33 Fig. 15. Suture, natural size. The second lateral saddle has, by an oversight on the author's part, been drawn too decidedly as trifid. It is really a bifid base with a prominent outer marginal and much like the same saddle in fig. 13. Celendin, Peru; Upper Cretaceous; my collection. 254 U. S. GEOLOGICAL SURVEY MONOGRAPH XLIV PL. r MOJSISOVICSIA, BUCHICERAS, ROEMEROCERA3 PLATE II 255 PLATE II. ROEMEROCERAS, PaRATISSOTIA. Page. Figs. 1-3. Roemeroceras gabbi Hyatt 30 Figs. 1, 2. Xatural size. 3. Enlarged suture. Coll. Acad. Nat. Sci. Philadelphia. Quebrada de Colpamayo, Peru; Upper Cretaceous; all after Gabb. Figs. 4-6. Roeineroceras suhjilannm Hyatt 34 Figs. 4, 5. Natural size. 6. Suture, X 2. Cajamarca, Peru; Upper Cretaceous; my collection. Figs. 7-11. Paratissolia serrata (Hyatt) 51 Figs. 7, 8. Natural size. 9. Fig. 8 enlarged. 10. Center of fig. 8 enlarged to show section of young and solid keel. 11. Lateral and dorsal suture of fig. 7 above the break. Cachiyacu, Peru; Upper Cretaceous (Senonian?); my collection. 256 U. S. GEOLOGICAL SURVEY MONOGRAPH XLIV PL. II R0EMER0CERA5, PARATISSOTIA. PLATE III. MON XLIV — (»;j 17 , 257 PLATE ITT. Paratissotia, Sphenodiscus. Page. Figs. 1-6. Puralissotia regularin II yalt 53 Figs. 1-3. Natural size. The venter is restored in fig. 1, and in flg. 3 the hollov keel is restored except in lowest volution of section, which is as seen in fig 4. 4. F.nlarged view of section of venter of lower whorl of fig. 3, showing hollow keel on its first appearance. 5. Suture of first quarter of outer volution of fig. 2; dor.9 Buncombe Hil-ls, Pontotoc County, Miss.; Ripley group, Upper Cretaceous; Coll. Frederick Braun. ■2fi4 U. S. GEOLOGICAL SURVEY Monograph xliv pl. vi SPHENODISCUS. PLATE A^I. 265 PLATE VII. Sphenodiscus lobatus (Tuoiiiey). ( Page 66. ) Figs. 1, 2. Pontotuc Cuunty, iliss. ; Ripley group, Ui>ijer Cretaceou.«; foil. V. S. Nat. Mils., Xo. 2403, I natural size. 266 PLATE VIII. 267 PLATE V I n . Sphenodiscus. Page. Fi(;s. 1 , 2. .SphcitodiKCUs lenticularis (Owen ) 71 Fig. 1. Young of supposed typical forni, natural size. See also PI. IX. 2. Suture of same X Gl. Moreau River,? Dakota; Fox Plills group; Coll. T'. S. Nat. Mus., Xo. 7754. Figs. 3-7. Sphenodhcua lenticularix \;\r. splendeiis Hyatt 75 Figs. 3, 4. Views of fragment.'? showing lateral sutures ami internal, loose younger volution, natural size. 5. Dorsal suture of one side of about same age as the one painted in on fig. 3, natural size. t>. Antisiphonal lobe of fig. 5, much enlarged. 7. First three saddles and siphonal saildle to show outlines on the next inner volution to that of fig. 3, natural size. South Dakota; Fox Hills group; my collection. 268 U. S. GEOLOGICAL SURVEY MONOGRAPH XLIV PL. ^nv|v. SPHENOOISCUS. PLATE IX. 269 PLATE IX. Sphenodiscus. Page. Fic;s. 1-6. Sphe.nodisvHx Untindqrix (Owen ) 71 Fig. 1. Suture of parancpionic .substage, X -h. 2. Details of fiphunele, showing what seemed to be a collar above and a jiro- limgeii funnel reaching frf-in the septum to the opening of the collar. 3. Sutures of the neanic stage, showing the division of the first primitive lat- eral into three saddles, first, second, and third of the later stages, and the mode of increase of the so-calleil auxiliary saddles and lobes on the line of involution, X 5. 4. Section of the two j-oungest volutions obser\ed, X -^ 4. 5. Lateral suture of later but not fully adult stage, X 6. 6. Dorsal suture of same age, X S. Rock Creek, Wyoming; Fox Hills group; Cull. Vale Ciiiversity, Xo. 1697. Fi(is. 7-9. SphenodisrtiK loitifii/arii! var. missisHppiensis Hyatt 77 Fig. 7. Lateral suture, natural size. S. Dor,«al suture of same age, but one-fifth over the natural size; aclual meas- urement is 48 mm. instead of 60 mm., the length of the figure. 9. Lateral suture, natural size, from specimen in Coll. Acad. Xat. Sri. Phila- delphia. Three miles northeast of Ripley, Miss.; Ripley group; Coll. I'. S. Xat. .Mus., No. 2086.Sc. Fig. 10. SjilHiiitilitnis beechcri Hyatt 78 Suture, natural size. Fox Hills grou]>; Coll. Mus. Conip, Zool., Cambridge. Flos. 1 l-lo. Sphenodiscus lobalns (Tuomey) , 66 Fig. 11. Right side. 12. First three saddles of left side at same age, natural size, l.'i. First three saddles of left side of the youngest suture shown on I'l. \'II, fig. 1, natural size, for comparison with fig. 12. Buncombe Hills, Pontotoc County, Miss.; Ripley group; Coll. Frederick I5raun, Brooklyn, X. Y. 270 U. S. GEOLOGICAL SURVEY MONOGRAPH XLIV PL. U SPHENODI5CUS, PLATE X. 271 PLATE X. COILOPOCERAS, SpHENODISCUS. Page. Fiiis. 1 —J. ('oilopocL'ras iiorimexirdnuin Hyatt 94 Figs. 1-3. Natural size, showing Imllow keel, etc. 4. One entire lateral suture and parts of two otliers, x ^- The terniinaticms of the saddles were more or less pointed depressions in the east and, were not at lirst observed. Near Carthage, X. Mex.; my collection. Fu;s. .5-21. Co'dopoceras eolletl Hyatt 91 Figs. .5. 0. Natural size, section partly restored; see also PI. XI, fig. 1. 7. Lateral suture same as in side view, X -■ 8. The dorsal suture of same age, but a suture or two later. 9. Youngest suture shown in fig. .5, X -, showing the markeil changes that occur on this volution. 10. First to thinl suture of nejiionic stage, X '-0. 11a. An entire suture of latter ])art of first volution, X 20. 11. Two entire sutures of fir.st quarter of second volution, X 20. 12. Entire suture of fourth quarter of fourth volution. X 8, when the sutures are beginning to show sul)division. 13. The protocoiich and part of the first volution. X --. same age as fig. 14. 14. More enlarged side view of the same. 15. 16. An older stage of the same shows less of the protocomh and more suture.s. 17, 18. A still oilier stage, showing the decreasing transverse diameter of the volutian in the goniatitic stage, and the fir.-^t constriction or mark of a nepionic aperture. 19, 20. An older stage of same, center of fig. (i, and al.-'O of tig. 1, I'l. XI. 21. Shows the hyponomic sinus of constriction or permanent aperture given in figs. 18 and 19. The normal rate of growth and increase in diameters of volution has begun in this nepionic substage. Xear Carthage, X. Mex.; my collection. Fig. 22. [Suture of Sphenodiscus introduced for comparison. — T. \V. S.] 272 U. S, GEOLOGICAL SURVEY MONOGRAPH XLIV PL. X COILOPOCERAS, SH PENOD ISCUS. PLATE XI. MOX XLIV— 03 18 273 PLATE XI. C0II.OPOCERAS, EULOPHOCERAS, MeTOICOCERAS. Page. Fk;. 1. Coilopoferas colleli Hyatt ^^ Section same as PI. X, fig. (>, enlarged. Fifis. 2-6a. EHlophocema nataleme Hyatt 86 Fig. 2. Side taken before specimen was ground to show section. 3. Section somewliat more than natural size, and somewhat restored, shows the umbilicus on the right completely filled by the shell layer.s. This filling occurs in the adolescent stage, inclosing the dark spots on Ijoth sides of the center, which indicate that the shell did not fill the umbilici at an earlier stage. 4. Enlarged view of center restored. 0, 6. Shows keel to have been solid at this age. 6a. Enlarged drawing of hollow keel of venter connected by a dcitte)efore tht- nepionic tube began to be formed, and the first two sutures. 9. Optical section of same along dotted line in fig. .S ami from frcmt <>i view shown by the arrow. 10. Front view of the specimen before removal of the outer volution, X 36. 11. Enlarged view of the ciecum and fir.st section of sipliuncle, showing also the ventral lobe divided by a siphonal saddle. 12, 13. Neanic stage, showing the aspidoceran-like form and tubercles, X 6. 14, 1.5. A little older stage with living chamber complete at the umliilical shoulder, over 1/2 volution in length, X 6. Back of this shows rormded venter of the neanic stage just becoming divided by the incoming of two rows of tubercles. 16, 17. Early ephebic substage. 18. Sutures of fig. 12 about fir.'^t quarter of fourth volution, X 12. 19. Suture of second quarter of same volution. 20. Suture of probably fourth quarter of same volution. 21. Dorsal suture of the second volution, X 12. 22. Dorsal suture of what was considered to be the last oi fifth or part of sixth volution, X 12. 23. Dorsal suture later in age than fig. 22, X 12, of same age as suture PI. XIII, fig. 1. 24. Lateral suture of fig. 16 enlarged 3 diameters. The ventral lobe has been distorted by setting the siphonal saddle at an eccentric angle. Texas; Colorado epoch; my collection. See PI. XIII for other figures of this species. 274 U. S. GEOLOGICAL SURVEV Monograph xliv pl. .-LJV' -^^0' G V ,-^o~- I 6" COILOPOCERAS. EU LOPHOCERAS, METOICOCERAS PLATE XII. 275 PLATE XII. COILOPOCEEAS, ACONECERAS, SpHENODISCUS. Page. Figs 1-3 CoUopoceran springrri Hyatt 96 Fig. 1. Suture of right side of shell. 2. Suture of left side. 3. Antisiphonal lobe and first dorsal saddle. Lower part of lobe below dotted line and right side is restored; the point, however, was seen to be bifid. All natural size. Eit du Plain, Colfax County, N. Mex.; Colorado ei)och, Upper Cretaeeous; C'oll. Mus. Comp. Zool. Figs 4-6 Aconeceras nisum (A' Orbigny) 100 Figs. 4, .5. Natural size (after d'Orbigny's figures). 6. Sutures enlarged, showing similarity to phylloceran outlines. Fig. 7 CoUopoceras r/rossouirei Hyatt 1 00 Figure of sup-posed Sj/henodismx reqtiicnicinus d'Orh., showing coilopoceran suture. (After Grossouvre. ) Fig 8. Sphenodiscus konincki Hyatt .S2 J'ig. 8. Suture natural size. Part of one suture is shown and this is continued by the auxiliaries of the next suture below. Near Maestricht; Senonian; DeKoninck Coll. Mus. Coiuj). Zool., Candiridge. 276 U. S. GEOLOGICAL SURVEY MONOGRAPH XLIV PL. XII COILOPOCERAS, ACONECERAS. S P H E NOD ISC US. PLATE XIII. 277 PLATE XIII. Metoicxx'era.s. Pa 28. Fic;s. 1-2. Metoiriireriis stirallnii (Shuniard) , 118 Fig. 1. Same a.M PI. XI, figs. 20-21!. First tliree saddles and two lobes of lateral suture, X 12, to show mode of division of saddles and their distinct marginals at this late neanic substage. 2. Gravson County, Tex; Coll. D. S. :\Iartin. Figs. 3-5. Metoicoceras u-hilti Hyatt 122 Fig. 3. Shows shell on part of outer volutiim ani bnidbense Hyati ". Figs. 9, 10. Natural size. 11. Suture of left side of the second quarter of outer volution, X 2J. The living chamber extended from the crack in the specimen, fig. 10, for the remaining one-half volution, and was mo.st ]irohably nearly complete. Upper Kanab Valley, Utah; Colorado epoch; Coll. I^. S. Nat. Mus. Figs. 12-18. Heinzia matura Hyatt - - - 1S2 Fig. 12. Entire specimen, right side. 13. Same separated and center excavated, left side. 14. Front view of same, center one-half restored. 15. Ventral view of fig. 12. 16. Suture at place marked by arrow in fig. 13, X 7, actual length 3 mm. 17. Dorsal suture, X 8, of second cjuarter of outer volution of fig. 12, one-half actual diameter 2 mm. 18. Suture of right side fourth quarter of outer volution <>i fig. 12, X 3. All natural size excejjt figs. 16, 17, and 18. Escragnolles, France; Barremian; Coll. Mus. Comp. Zool., Cambridge. Figs. 19, 20. Heliiziapi-tirincialis (d'Orbigny) 131 Fig. 19. Dorsal suture next to outer volution across the umbilicus and opposite termination of outer volution, X 9, one-half actual diameter 1.5 mm. Of same type, but more immature at the same age than in Heinzia matura. 20. Natural size. Locality and collection same. " No description of this species was found in the manuscript. — T. W. S. 282 U. S. GEOLOGICAL SURVEr MONOGRAPH XLIV PL. XV METOICOCERAS, HEINZiA. PLATE XVI. 283 PLATE XVI. Heinzia, Knemicera.s. Page. Fins. 1-3. Heimia prorinciaVis (d'Orbigny) 1.31 Figs. 1, 2. Same as PI. XV, fig. 20, broken to shpw young, X 3. 3. Lateral suture of the second quarter of outer volution of PI. XV, fig. 20, X 4. Escragnolles, France; Barremian; Coll. Mus. Comp. Zool., Cambridge. Figs. 4-8. Knemiceras syriacmn (von Buch) 146 Fig. 4. Natural size, showing length of living chamber, over one-fourth of a volution. Coll. Mus. Comp. Zool., Cambridge. 5. Lateral suture, X -\- 6. Uncompressed typical fossil. Coll. Yale JIus. 7. Part of suture of right side, X 2A, to contrast with next figure. 8. Suture of left side, X 3. Outlines perfectly preserved. Mount Lebanon, Syria; Cenomanian. Figs. 9-10. Knerniceras compressuni Hyatt. Natural size 149 Locality, same as last; Coll. Mus. Comp. Zool., Cambridge. Figs. 11-14. Knemkerax compressum var. subcomjjresfmm Hyatt 150 Fig. 11. Specimen in collection of Columbia University. 12. Section showing transition from a rounded young to the flat and then con- cave venters of the succeeding stages, X 2, from specimen in Mus. Comp. Zool., Cambridge. 13a. Enlarged view of centei . 13b. Enlarged view of protoconch and first volution with first and second sutures. 14. One of Conrad's specimens, natural size. Suture abraded. Coll. Yale Mus. Locality, same as last. Figs. 1.5-18. Knemiceras comprensnm Hyatt 149 Figs. 15, 16. Type of species. Sutures abraded. 17. Suture from line of involution to first lateral lobe at breadth of 54 mm. on left side. 18. Suture on right side to third lateral saddle at breadth of 63 mm. Locality, same as last. Fig. 19. Knemiceras comp ressniii yar. subcompressum Ptyatt 150 Ventral view, natural size, of specimen in collection of Columbia L^niversity. For sutures see fig. 11. Locality, same as last. 284 S. GEOLOGICAL SUHVE MONOGRAPH XLrV PL. XVI HEINZIA. KNEMICERAS PLATE XVII. 285 PLATE XVII. SUBPULCHEIXIA, NiCKLEMA, PuUHKI>LIA, KnIEMICERAS, PrOTENGONOCEKAS. Page. Fins. 1-5. Subpulehellia castellanensis Hyatt 140 Figs. 1, 2. With shell complete on side of fig. 1. 3, 4. Same fossil, shell partly taken i.iff. Right side of fig. 3 shows length of living chamber about one-half of last volution. ' 5. Lateral suture of fig. 3, X 3. All natural size except fig. 5. Castellanes, France; Neocomian; Coll. Mus. Comp. Zool., Cambridge. Figs. ti-S. Nicklesia dumasiana (d'Orbigny) 139 Figs. 6, 7. Natural size. IS. Lateral suture, X 3. Locality and collection same as last. Figs. 9-12. Pnlchellki compressissima (d'Orbigny ) 142 Figs. 9-11. Natural size. 12. Suture after Nicklcs, Pal. sud-est de I'Espagne, pi. 3, fig. 11), X o. Locality and collection the same. Figs. \'A-\o. Knemiceras attenmilum ( Hyatt l 151 Figs. 13, 14. Natural size; shows living chamber nearly three-fourths of a volution. 15. Suture, X 2. • Celendin, Peru; Cenomanian? Figs. 16v-20. Protengonoceras ydbhi ( Bohm) 1.53 Fig. 16. Shows living chamber to have one-half a volutimi in length. .Shell is preserved on the living chamber. 17. Section shows the concave venter witli lateral ridges at an early stage. 18. Ventral view of same. 19. Septum of same, X 2. All natural size except the last, and all in Coll. Mus. Comp. Zool., Cambridge. 20. Specimen in Coll. .\cad. Nat. Sci. Phila. Showing living chamber one-half of a volution, part of aperture on right side, and old-age folds. .\rivechi, Sonora, Mexico. 286 U. S. GEOLOGCCAL SURVEY MONOGRAPH XLIV PL. XVII SUBPULCHELLIA NICKLESIA PULCHELLIA, KNEMICERAS, PROT EN GON OC E R AS. PLATE XVIII. 2S7 PLATE XVIII. Knemiceras, Engonoceras, Protengonoceras. Page Figs. 1-3. Knemiceras gabbi Hyatt 1.52 Figs. 1, 2. Natural size. (After Gabb.) 3. Lateral suture enlarged. (After Gabb.) Quebrada de Huari, Peru; Cenomanian? Figs. 4, .5. Engonoceras hrlriderense ( Cragin ) 158 Figs. 4, 5. Lateral and ventral views. Belvidere, Kaiis. ; Washita epoch; Coll. Cragin, Colorado College. Figs. 6-9. Proienfjonocera.t planum Hyatt 15fi Figs. 6, 7. Lateral and ventral views. X 2. 8. Lateral suture, X 2; the auxiliary sadrlles Nos. 8 to 10 shouM be a trifle broader. 9. Dorsal suture of the same age, X 2. Texas, my collection. 288 U. s. gEOloG'cal survey Monograph xLrv pl. xvill KNEMICERAS, ENGONOCERAS. PROTENGONOCERAS. PLATE XIX. MON XLlv— 03 19 289 PLATE XIX. Engonoceras. Page. Ficis. l-tl. Kmjijnucerds udileni (Cragin) 159 Figs. 1,2. Type specimen from near Lindsborg, Kans., natural size. 3. Lateral suture of same, slightly enlarged. 4,5. Specimen from McPherson County, Kans. Natural size, showing living chamber proliably almost complete along the umbilical shoulder and about one-half of a volution in length. The crease on the side of the venter of fig. 5 is an accident due to conijiression. Coll. U. S. Nat. Mus. R. Lateral suture of opposite or left side, X 2i. The curvature is somewhat less than it is on the specimen. Kiowa shales, Comanche series, Lower Cretaceous; my collection. Flos. 7-14. Engonoceras serpendnum (Cragin ) 162 Figs. 7, S. Natural size, living chamber one-half of a volution probably nearly com- plete on umbilical shoulder. The venter of inner volution of fig. 8 ia decidedly concave. 9. Lateral suture, X 2. 10. Part of sutures of young fragment, X 2. This specinicn is fmiu near Deni- son, Tex. 11. V'ariety with broad ends tcj the cost;e and crowded peculiar suture.s. 12. Lateral sutures, X 2. 13. Ventral view of cast, with similar costfe. 14. Suture of same more like tlio.se of fig. 9. This is not due tn difference of age. The last 5 and half of sixth saddle arc dorsal. Four and one-half miles northea.st of Gainesville, Tex., Deni.son; Washita epoch; Coll. U. S. Geol. Survey. Fi(is. 15-17. Engonoceran rclurduni Hyatt « IHO Fig. 15. Natural size, showing the late age at whii-h the venter remains angulated, flat, and without tubercles. The rounded venter of the older stage is in part due to abrasion. 16. Shows what was seen of the lateral sutures. 17. Dorsal suture of same age as oldest suture on fig. 16. Near Pottsboro, Tex.; Cpper Comanche (Grayson). Washita ejioch; Coll. U. .^. (tcoI. Survey. "The specimen here figured as E. relarilum is describe ^ 13 engonocEras, PLATE XXI. 293 PLATP] XXI. Engonoceras. Page. Fid. 1. Enijonocerns pierdenale \ar. commt.nn' Hyatt 165 Fig. 1. Suture, X 2. Bell County, Tex.; Fredericksburg group, Comanche series. Coll. U. S. Nat. Mus., Xo. 8301. Figs. 2-6. Engonoceras subjeclum Hyatt 168 Figs. 2, 3. A specimen from Gabriel, Williamson County, Tex. ; Con. Mus. Comp. Zool., Cambridge. 4. Portion of septum of same spei'imf n — the middle one of the three indis- tinctly shown in fig. 2, x 2. 5. Last septum of same specimen, X 2. 6. Septum of a smaller specimen from same locality, X 2. Washita (?) group, Comanche series. 294 U. S. GEOLOGICAL SURVE MONOGRAPH XLIV PL ENGONOCERAS. PLATE XXII. 295 PLATE XXII. Engonoceras. Page. Figs. 1-5. Engonoceras suijectum Hyatt 168 Fig. 1. Specimen from Duck Creek beds, near Denison, Tex. ; Coll. U. S. Geol. Surv. 2. Suture of same, very slightly abraded, X 2. 3. Specimen from Grayson, Tex.; Coll. D. S. Martin. 4. Suture of same, X 2. 5. Suture of specimen from Tarrant County, Tex.; Coll. Cragin, Colorado College. Washita (?) group, Comanche series. Figs. 6-10. Engonoceras gibboKum Hyatt 171 Fig. 6. Lateral view of a small specimen from Goodland limestone, 15 miles west of Denison; Coll. V. S. Geol. Surv. 7. Ventral view of same, partly restored. 8. Septum of same, X 2. 9. Fragment doubtfully referred to the species, from Bell County, Tex. ; Coll. V. S. Nat. Mus., No. 8301a, X 2. 10. Septum of same, partly rc.s^tored, >; 2. Fredericksburg group, Comanclie series. 296 U. S. GEOLOGICAL SURVEY MONOGRAPH XLI^ PL. XXII ENGONOCERAS. PLATE XXIII. 297 PLATE XXIII. Engonoceras. Page. Figs. 1-6. Engonoceras gibboftum Hyatt 171 Figs. 1, 2. Specimen from Cook County, Tex. ; my rollection. 3. Suture of same, X 2. i, 5. A fragment from tiie Goodland limestone, 1.5 miles .«JOUthwest of Gaines- ville, Tex. 6. Suture of same, X 2. Fredericksburg group, Comanche series. Figs. 7-9. Engoiiocerds Motteyi Bohm 175 Figs. 7, 8. Young specimen in Cragin Collection, Colorado College. 9. Suture of same, X 2. Fredericksburg group [?], Comanche series. 298 ( U. S. GEOLOGICAL SURVEY MONOGRAPH XLIV PL. XXIII ^ ¥g r Ifar-"'- % ^J\ / s^ #4 ENGONOCERAS. PLATE XXIV. 299 PLATE XXIV. Engoxoceras. Page. Figs. 1-5. Engonoceras stoUeyi Bijhm • 1~5 Figs. 1, 2. Specimen in my collection, partly restored. 3, 4. Specimen in Coll. Hill, U. S. Geol. Surv. ["Hill 4a."] (?) .5. Suture of same, X 2. This is somewhat worn down. Fredericksburg group [?], Comanche series. Figs. 6-8. Engonoceras complicalnm Hyatt 1'5 Figs. 6, 7. Type specimen from near Austin, Tex. Coll. Hill, U. S. Geol. Surv. 8. Suture of same, X 2. Comanche Peak limestone of Fredericksburg group, Comanche series. 300 U. S. GEOLOGICAL SURVEY MONOGRAPH XLlV PI. XXIV ENGONOCERAS. PLATE XXV. 301 PLATE XXV. Neolobites, Metengonoceras. Page. Figs. 1-4. Neolobites chqfatl Hyatt 1~8 Figs. 1, 2. Copies of Choffat's figures 3a, 3b, published as N. vibrayeanus. 3, 4. Suture of probably the same species (after Choffat). Cenomanian; Portugal. Figs. 5-9. Melengoiioreras inscriptmn Hyatt 180 Fig. 5. Section of fragmentary specimen from west of Walnut Springs, Texas- Coll. Cragin, Colorado College. 6. Suture of same, enlarged. 7. Suture of a small fragmentary specimen from 12 miles northwest of Decatur, Tex.; Coll. U. S. Geol. Surv. 8. Suture of fragment from 15 miles west of Denison, Tex.; Coll. U. S. Geol. Surv. 9. Ventral view, partly restored, of specimen from 12 miles northeast of Decatur, Tex. For other figures see PI. XXVI. Fredericksburg group, Comanche series. 302 U. <=: GEOLOGICAL SURVEr MONOGRAPH XLIV PL. XXV NEOLOBITES, METENGONOCERAS. PLATE XXVI. 303 PLATE XXVI. Metengonoceras. Page. Figs. 1^. Metengonoceras inscriptum Hyatt 180 Fig. 1. Enlarged suture of specimen represented by figs. 2 and 3, and by PI. XXV, fig. 9. 2, 3. Specimen from 12 miles northeast of Decatur, Tex. 4. Suture of large fragment from 9 miles from Austin, on Beecaves road. Coll. IT. S. Geol. Surv. [This drawing was labeled M. ambiginiiii, but the specimen is described under M. inscriptum. — T. W. S.] Fredericks^burg group, Comanche series. Figs. 5-7. Metengonoceras ambiguum Hyatt 183 Fig. 5. Side view of type. 6, 7. Suture of same specimen, X 2. Nine miles from Austin, on Beecaves road; Fredericksburg group, Comanche Peak limestone, Comanche series. Coll. U. S. Geol. Surv. Fig. 8. Metengonoceras aculum Hyatt 184 Side view of fragmentary type specimen. Elm Fork, Dallas County, Tex.; probably Eagle Ford shales, Upper Cretaceous. Coll. Mus. Comp. 2tool., Cambridge. 304 U. S. GEOLOGICAL fiURvEV MONOGRAPH XLIV PL. 6 ^ ^ f^ % ' ^ ^''^*^' 7 A. f-^' ^-^M '..>,• MX^ r METENGONOCERAS. PLATE XXVII. Mox XLiv— 03 20 305 PLATE XXVII. Metengonocekas, Flacenticeras. Page. Fiiis. 1-2. Meteiir/imorerus acutuni, Hyatt .■ 184 Fig. 1. Ventral view of type specimen. 2. .Septum of same, X 2. Elm Fork, Dallas County, Tex., probably Eagle Ford shales, Upper Cretaceous. Coll. Mus. Comp. Zool., Cambridge. Fuis. 3- 14. Metengonoceras dumhli ( Cragin) 18.5 Figs. 3, 4. Lateral and ventral views of specimen described. 5. Section of same. 6. Inner whorls of fig. 5, enlarged. 7. Center of same, still more enlarged, showing antisiphonal lobe, the inner- most whorls having dropped out. 8. Section of whorl in neanic stage, X 10. e. Adult lateral suture, X 2J. 10. Last lateral suture, X 2J. > 11. Dorsal suture continuous with lig. 9, enlarged. 12. Dorsal suture one-fourth volution older than fig. 11, enlarged. 13. Lateral and part of dorsal suture of neanic stage, X 18. 14. Dorsal suture of somewhat later substage than fig. 13, enlarged. Four miles east of Whitesboro, Tex.; Eagle Ford shales. Upper Cretaceous; Coll. U. S. Geol. Surv. Ficis. 1.")-! 7. Phiceidiceras syrUde (Morton ) J 205 Fig. 15. Suture of the type in Coll. Acad. Nat. Sci. Phila. 16. Lateral suture of var. halei, Coll. Bost. Soc. Nat. Hist., No. 8577. 17. Dorsal suture of older part of same volution as fig. 16. Greene County, Ala.; Eutaw beds (?), Upper Cretaceous. 306 U. S. GEOLOGICAL SURVEY MONOGRAPH XLIV PL. XXVIJ "JiiA ^Jn.-'it. V? ' '^■•*'*'*"^ 17 METtNGONOCERAb PLACENT IC t RAS PLATE XXVIII. 307 PLATP] XXVIII. Placenticeras syrtale (Morton). (Page 205.) Fics. 1, 2. Two views of tlie type, Coll. Acad. Nat. Sci. Phila. (For suture, see PI. XXVII, %. 15.) 3, 4. Type of var. Iiah-i, Bost. Soc. Nat. Hist., No. 8.577. (For suture, see PI. XXVII, figs. 16 aud 17.) 5, 6. Another specimen of var. lialei, same collection. Eutaw bed8(?). Upper Cretaceous, Greene County, Ala. 308 U. S. GEOLOGICAL SURVEY MONOGRAPH XLIV PL. XX PLACENTICERAS. PLATE XXIX. 309 PLATE XXIX. Placenticeeas GUADALUPE (Roemer). (Page 197.) Fig. 1. Lateral view of a large specimen. 2. Aperture view of same considerably restored. ?>. Section of same. 4. Enlarged section of inner whorls of same. Xear Fort Worth, Tex.; Taylor beds (?); Upper Cretaceous; my collection. 310 U. S. GEOLbcrCAL SURVEY MONOGRAPH XLIV PL. XXI>i PLACENTICERAS. PLATE XXX. 311 PLATE XXX. Placenticeras sancarlosense Hyatt. ( Page 200. ) Fig. 1. Side view of an average-sized specimen 2. Aperture view of same. 3. Suture of same, X 2. San Carlos, Presidio County, Tex. ; San Carlos beds ; Upper Cretaceous ; Coll. V. S. Geol. Snrv. 312 U. S. GEOLOGICAL SURVEV Monograph vliv pl. xxx PLACENTICERAS. PLATE XXXI. 313 PLATE XXXI. Placenticeras. Page. Figs. 1, 2. Placenticeras sancarlosense Hyatt 200 Fig. 1. Section of a small specimen — "passage form between this specie.? and guadalupse." 2. Side view of same. San Carlos, Presidio County, Tex.; San Carlos beds, Upper Cretaceous; Coli.U. S. Geol. Surv. Figs. 3-5. Placenticeras nev)herryi Hyatt 203 Fig. 3. Side view of the type specimen. 4. Section of same. ■5. Aperture view of same. Near Presidio Del Norte, Chihuahua, Mexico; San Carlos beds. Upper Cretaceous; Coll. Columbia University, No. 10073G. 314 b. S. GEOLOGJCAL SURVEY MONOGRAPH XLIV PL. PLACENTICERAS PLATE XXXII. 315 PLATE XXXII. Placenticeras sancarlosense var. pseudostktale Hyatt. (Page 200. ) Side view of type of variety (see PI. XXXIII, tig. 1). Near Fort Worth, Tex.; Taylor beds (?), Upper Cretaceous; my collection. 316 U. S. GEOLOGICAl SURVEY MONOGRAPH >L1V PL. XXXII PLACENTICERAS PLATE XXXIII. 317 PLATE XXXIII. Placenticeras. Page. Fii;. 1. Placenticeras sancarlosense var. pseudo»yi-lale Hyatt 200 Fig. 1. Aperture view of specimen figured on PI. XXXII. Fias. 2-4. Placenticenis planum Hyatt 202 Fig. 2. Aperture view of medium-sized specimen partly res^tored. 3. Side view of same. 4. Peripheral view of another specimen showing less development of nodes. (See PI. XXXIV, fig. 1.) San Carlos, Presidio CViunty, Tex.; San Carlos beds. Upper Cretaceous; Coll. V. S. Geol. Survey. 318 U. S. GEOLOGICAL SURVE PLACENTICERAS- PLATE XXXIV. PLATE XXXIV. Placexticeras plaxcm Hvatt. (Page 202.) Fig. 1. Side view of the small specimen rejiresented by PI. XXXIII, fig. 4. 2, .3. Aperture and side views of a larger specimen. San Carlos, Presidio County, Tex.; San Carlos beds, Upper Cretaceous; Coll. U. 8. Geol. Survey. 320 U. S. GEOLOGICAL SURVEY MONOGRAPH XLIV PL. XXXIV PLACENTICERAS. PLATE XXXV. MON XLIV— 03 21 321 PLATE XXXV. Placenticeras intercalare Meek. (Page 207.) Figs. 1, L'. Side and aperture views of medium specimen (see PI. XXXVI, fig. 1). [Black HilLs?], Fort Pierre, Upjier Cretaceous; Coll. Yale University No. 1863. 322 U. S. 6E0LOGICAL SURVEY MONOCRAPH XLIV PL. XXX^ PLACENTlCERAb PLATE XXXVI. 323 PLATE XXXVI. Placenticeras iNTERCALARE Meek. (Page 207.) Fifi. 1. Opposite side of specimen figured on PI. XXXV. 2, 3. Side and aperture views of small specimen, No. 21041). 4. Suture of same, X 2. 5. Parts of two septa of Geological Survey specimen from Harper, Wyo., represented by PI. XXXVII, figs. 1, 2. Fort Pierre, Upper Cretaceous, Coll. Yale University (except fig. 5). 324 U. 5. GEOLOGICAL SURVEY MONOGRAPH XLIV PL. XXXVl PLACENTICERAS. PLATE XXXVII. 325 PLATE XX XY II. Placekticeras inteecalare Meek. {Page 207.) Figs. 1, 2. Fragmentary small specimen from near Harper, Laramie Plains, Wvo. ; Coll. U. S. Geol. Survey. (See PI. XXXVI, fig. 5. ) 3. Section of specimen "approximating to some varieties of P. sliuilinil," from Ponil t'anyon, New Mex.; Coll. U. S. Nat. Mus., No. 9735. 4. Side view of same specimen. (For suture, see PI. XXX VIII, lig. 1.) ^lontana group, Upper Cretaceous. 326 U. 6. GEOLOGICAL SURVEV Monograph xliv pl. xxxvil PLACENTICERAS. PLATE XXXVIII. 327 PLATE XXXVIII. Placenticeras. Page. Fig. 1. Placenticeras intercalare Meek 207 Suture of specimen from near Harper, Wyo. (See PI. XXXVII. ) Montana group, Upper Cretaceous. Fig. 2. Placenticeras intercalare var. costalitm Hyatt 207 Side view of type of variety, my collection, purchased from Ward. "Probably from Black HilKs S. Dak. Montiina group, Uppjr Cretaceous. 328 U S. GEOLOGICAL SURVEY MONOGRAPH XLIV PLACENTICERAS. PLATE XXXIX. 329 PLATE XXXIX. Placenticekas. Fi(is. 1, 2. Phwenlicenix hitercalare var. costatum Hyatt L'n7 Figs. 1, 2. Aperture view and suture of specimen repreeenteil 1>v PL XXX^'I1I, fig. 2. Fk;s.' 3-6. Fliicevlicetris placenta ( Dekay ) 211 Fig. 3. Fragment of a small specimen from Chesapeake and Delaware Canal, Coll. Acad. Nat. Sci. Phila. 4. f~uture of same, X 2. 5. Side view of small specimen from Leni>la, N. J. (). Sutures from smaller end of volution rejn'e-^ented l)y lig. 5 enlarged four diameters (see PI. XL, figs. 1, 2). Matawan CM formation, Upper Cretaceous.. 330 U. S. GEOLOGICAL SURVEV MONOGRAPH XLIV PL. XXXIX V PLACENTICERAS. PLATE XL. 331 PLATE XL. Placentickras. Page. Figs. 1,2. Placentireras phicenta ( Dekay 1 - 211 Fig. 1. Peripheral view of .specimen represented by PI. XXXIX, fig. h. 2. Side view ot same, enlarged nearly two diameter.'*. Figs. 8-7. Placenticerax slantoni var. bolU Hyatt 214 Figs. 3, 4. Aperture and side views of the small specimen from Tarrant County, Tex., in tlie Martin collection, Rutgers Female Institute, described liy Meek as P. intercalare. ri. Suture of same, X 2. 6. Fragmentary specimen from Horton's mill, Dallas t'onnty, Tex.; Coll. Mas. Comp. Zool., Cambridge. 7. Lateral and internal suture of same, X 2. (See PI. XLI.) Taylor beds (?), Upper Cretaceous. 332 U. S. GEOLOGICAL SURVEY MONOGRAPH XLIV PL. XL PLACENTICERAS. PLATE XLI. 333 PLATE X L I . Placenticeras stantoxi \ur. v.otaa Hyatt. (Page 214.) Fui. ]. Sectional view of gpeciraeii represented l)y PL XL, ligs. 6 ami 7. 2. Restored section of same. 3, 4. Living chamber of a larger speeiirieii. 5. Last suture of same specimen. 6, 7. Living chamber of another specimen. Horton's mill, Pallas County, Tex.; Taylor beds (?), Upper Cretaceous; Coll. Mns. Comp. Zool., Cambridge. 3.34 S. GEOLOGICAL SURVE MONOGRAPH XLtV PL. XLI PLACENTICERAS. PLATE XLII. 335 PLATE XLII. Placenticekas stantoni viir. holli Hyatt. (Pafre214.) Fig. 1. Suture iif young specinieii enlarged abmit 'J\ diameters. 2. Part of living chamber ami last septa of a large specimen. Hurton'.s mill, Dallas County, Tex.; Taylor beds (?), Upper Cretaceous; Coll. Mus. Comp. Zool. Cambridge. 336 U. S. GEOLOGICAL SURVEY MONOGRAPH XLIV PL. XLII PLACENTICERAS. PLATE XLIII. MON XL1\— 03 23 ' 337 PLATE XLIII. Placenticekas. Page. Figs. 1, 2. Placentireras stantorii var. hoUi Hyatt 214 Fig. 1. Side view of small costate specimen. 2. Suture of same, X 2. Horton's mill, Dallas County, Tex.; Taylor beds {?), Upper Cretaceous; Coll. Mus. Com p. Zool., Cambridge. Figs. 3-11. Placeniiceras jjseudojdaccntd Hyatt 216 Fig. 3. Side view of small fragmentary specimen. -1. Sectional view of same. 5. Center of .same enlarged. 6. Ventral view of first whorls of same specimen much enlarged. 7. 8. Inner whorls of another specimen, natural size. 9, 10. Lateral sutures of last whorl of .same as indicated on tig. 7. Upper Kanab Valley, Utah; Colorado group; Upper Cretaceous ; Coll. U. S. Xat. Mus., No. 22.344. 11. Parts of internal sutures of ephebic stage when dorsoventral diameter of volution, measures 49 mm. Muddy Creek, Huerfano County, Colo.; Fort Benton formation: Upper Cre- taceous; Coll. U. S. Nat. Mus., No. 22199. 338 U. S. GEOLOGICAL SURVE' MONOGRAPH XLIV PL. XLIII PLACENTICERAS. PLATE XLIV. 3S9 PLATE XLIY. PlACENTICERAS PSEUDOrLACENTA Hyatt. (Page 216. ) Figs. 1, 2, 3. Three viewy of living chamljer of fragmentary .specimen. Bad Lands, near Black Hills; Upper Cretaceous, S. Dak.; luy collection. 340 U. S. GEOLOGICAL SURVEY MONOGRAPH XLIV PL. XLIV PLACENTICERAS. PLATE XLV. 841 PLATE XLV. Placenticeras. Page. Figs. 1, 2. Plcicmticeras pseudoplacenta var. occidentale Hyatt . . 217 Fit;. 1. A .specimen from the Tapper Missouri River; Coll. Coliiml.iia I'niversity, No. 10C22G. 2. Suture of a young specimen from Hortou's mill, Dalhis County, Tex.; Coll. Mus. Comp. Zool., Cambridge. Ficis. 3-16. Placenticeras whitfieldi Hyatt 221 Fig 3. Side view of small fragmentary specimen from Clifford, Nebr.. in Coll. Mus. Comp. Zool., Cambridge, enlarged. 4. Section of same showing venter of earliest whorls, X 3. 5. Center of same, X about 6i diameters. 6. F''irst two sutures and beginning of siphuncle of same specimen, nmch enlarged. 7. Beginning of sijihuncle of same after etching with acid, siill further enlarged, 8-10. Early stages obtained by breaking down a larger specimen from the Black Hills, South Dakota, in my collection; enlarged about 5 diameters. 1 1-14. Complete sutures from dorsum to venterof same stages as figs. 8, 9, 10. Fig. 11 is earliest suture visible on tig 9; lig. 12 is on last quarter of same whorl; fig. 13 is last .suture on iig. 10, and fig. 14 is nearly a volution earlier. 15. Dorsal (internal) sutures at diameter cif 15 nun. 16. Same at diameter of 40 nun. The last two figures may not be from same specimen as figs. 8-14. Montana grou[(, Upper Cretaceous. 342 S. GEOLOGICAL SURVEY MONOGRAPH XLIV PL. XLV ' r-. <'-^ <-i y^ PLACENTICERAS. PLATE XL VI. 343 PLATE XLVI. Placenticeras whitfieldi Hyatt. (Page 221.) Figs. 1, 2. Two views of a large specimen, tV actual diameter. Black Hills, South Dakota; Montana formation, Upper Cretaceous; Coll. Bost. Soc. Nat Hist., No. 11124. 344 PLATE XL VII. 345 PLATE XLYII. Placenticeras. Page. Figs. 1-4. Placenticeras whitfieldi Hyatt 221 Figs. 1, 2. Two views of the inner whorls of a small specimen from the t'pjier Missouri; Coll. V. S. IS^at. Mus., No. 18936. ">. Fragment showing peculiar sculpture of the inner shell layers. j)riilialily from Black Hills, South Dakota; my collection. 4. Another specimen showing similar sculpture from same collection and region. Montana group, Ujiper Cretaceous. Fig. 5. Placenticeras whitfieldi var. tuberculatum Hyatt 232 Fig. 5. Side view of the type of the variety. Montana group, Upper Cretaceous; Black Hills, South Paknta; my collecticm. Figs. 6-8. Placenticeras sjAUmani Hyatt 233 Figs. 6, 7. Two views of the fragment on which the species is based. 8. Part of weathered suture of same. Ripley formation f?), Upper Cretaceous; Mississippi (?); Coll. Acad. Nat. Sci. Phila. [Note. — Professor Hyatt indicated that the drawings for tigs. 6 and 7 were unsatisfactory to him, but the specimen is too imperfect to serve as the basis for a restoration]. 346 S. GEOLOGICAL SURVEY MONOGRAPH >LIV PL. XLVII PLACENTICERAS INDEX, [Names in italic are synonyms; fi^i^ires in bljick-fiu'c type are numbers of pages on which deseriptions appear: figures in italic denote illustrations.] Page. Acanthoceras 27 spiniferum Whiteaves 110 Acceleration of development 19-23.189-190 Acompsoceras Hyatt 105, note; 111-112 bochumense (Schliiter) H 1-1 12 essendense fSchliiter) 112 renevieri (Sharpe) 112 Aconeceras Hyatt J^8. 100. 101, note nisum (d'Orbigny) 90,99.100,270 Agassiceras 24 striarles 24 Amaltheus chrayi de Loriol 234 Ammonites 43 aUni naius Gabb ; 152 haiduri Keyserling 191. 192, 244 belvidcrends Cragin 158 bidorsatus Roemer 243, 244 bilobiitus Gabb 30 caicffli Karsten 133 catilf'i.'i d'Orbigny 143 clypci/onais d'Oihigny 85 Cf>mprcssissimus d'Orbigny 142 concHiaiiis Stoliczka 107 cou/o;u' d'Orbigny 114 crnmtesta Stoliczka 107 eunliffi. Stoliczka 107 dccidnus Hyatt 107 r^V/o //a" 'AS d'Orbigny 131,136,138 dispnr d'Orbigny 141 domei/kanus Bayle and Coquand 115 dumasianns d'Orbigny 139 euomphalus Sh&Tpe 107 civaldi von Buch 4G, 48 gahcitus d'Orbigny 135. 136, 142 gcirilinnus d'Orbigny 84.90 guadalupce Roemer 197, 241 haplnphijlla Redtenbacher 48 harttit ( Hyatt) 103 hdcr»jdeurus (Neumayr and Uhlig) 90 lafidavius Sharpe Ill Icvtirt/lnris Owen 71-75 lindUji Karsten 134 lobata Tuomey 66 mammUlaris 108-110 viammillatus 108 mantdli Sowerby 114, 115, 141 marcousnrnis d'Orbigny 90 milfrri Hauer 239 mo8(7ix/« d'Orbigny 84 7it8HB d'Orbigny 100 nodosoides Scbliiter llj orbif/nyanus Geinitz 235, 240 pcdrrnafis Roemer 59, 64, 82, 153, 165 Page. Ammonites— Continued. pierdenalis von Bnch 157, 165 placenta Dekay 211 pleuriscpta Conrad 59 polyopsis Dujardin 206, 207, 237, 240, 243 provincialis d'Orbigny 131 jiulchellus d'Orbigny 138. 140, 141 renevieri Sharpe 112 rcquieniamis d'Orbigny 99, 100 robini ThiolUere 46 rotomagcnsis Defrance 107 roj/cri'am(8 d'Orbigny lUl.note Tiisticiis ] 06, note siva Forbes 83 sivaMoi>i Shumard lis sijriarus von Buch 32, 146-150 s-i/rtali n UoTtou 205,207,237 syrtalis var. orbig-dyanus Schluter 235, 241, 242 si/Halls var. polyopsis Schluter 239 iamulitms Blanford 241 tcli/er Morton 233 truelU 19 uskas Stoliczka 115 vibraycanus d'Orbigny 149, 178, 240 i>ici7ialis Stoliczka 115 x^ielbanci d'Orbigny no woolgari Mantell 110 Ammonitinse 19:5,195-197,224 Cretaceous 102 disappearance of characters 23 of the Jura, relation to those of the Cretaceous 19-20 Arietidse 19 Arrestation of development 20-23 Aspidoceras 19, 106, 116 Baculites 21 Barroisiceras Grossouvre 26, '27, 104, 112 desmoulinsi Grossouvre 105 liaberfellneri Grossouvre 104 liaueri Grossouvre 105 Bathmoeeras 68, note Buchiceras Hyatt 25,26,27,84,88,112,144,145,191-193 atteriuatam Hyatt 33, 151 belviderense Cragin 158 bilobatum 25, 27-29, 30, 31 , 191, 25/, ewaldi (von Buch) 40.44,46,51 /o?/rHr^i Bayle 45,51 hartUi ( Hyatt) 103 serratum Hyatt 51-54 slizewiczi Fallot 49 swallovi (Shumard) 122 tissoti Bayle 42 Buchiceratidse Hyatt 24, 26, 35, 144 Calycoceras navicularis 113 347 348 INDEX. Page. Cardioceras 245 Carstenia Hyatt 129, 130, 133-IS4 caicedi ( Karsten) 133-135 gftleata (tVOrbigny) 135 liiuiigi (Karsten) 133,134 subcaicedi { Karsten) 134 tuberculata Hyatt 117, 134, 135, 136 Ceratii€» hartiii Hyatt 103 Ceratitinse 21 Cheloniceras 101, note; 117,129 royerianum 101, note; 116 Choffaticeras Hyatt 35, 37, 38 barjonni (Choffat) 37 douyillei (Peron) 38 meslei (Peron) 35,37,38 Classification, tabular statement of 15-18 Coilopoceras Hyatt 83,85,87-89,91, 100, 101, note colleti Hyatt (11-94, 95, 272, 271, gros,souvrei Hyatt 100, S76 noyimexieanum Hyatt 91-93, 94-96, 97, 272 requienianum (d'Orbigny) 99 springer! Hyatt 96-99, :.V6 Coilopoceratida- 24, 88-100; 101, note Cope, Edward D., on acceleration and retardation in development 20-23,189-190 Coronites 101,130,note coronatoides 130, note Cosmoceratida 101-105 Cretacic, nse of term 11 Desmoceras 101, note Desmoceratidfe 25 Development, acceleration and arrestation of. 19-23, 189-190 Diadochoceras Hyatt 105. 100, 107 nodosocostatum 106, 107 Diplaemoceras Hyatt 189, 192, 242-243 bidorsatum i Roemer) 243 canaliculatum Hyatt 243-244 Douvilleiceras Grossouvre 10.5-107, 108-109, 113 mammillare (d'Orbigny) 109, 113 orbignyi Hyatt 110 spiniferum (Whiteaves) 110 Eohinoids, parallelism in local development of 195 Engonoceras Neumayr 20, 21, 58, 14.5, 147, 153,156, 157-158,178-180,182, 196,198,242 belviderense (Cragin) 158-159, SS8 complicatnm Hyatt 175-177,300 emarginatum (Cragin) 1.59, 160, 177 (labbi Etihrn 153 gibbosum Hyatt 171-175, «9S, 29S inscriptum 1,83 pedcniafis Bohm 165 pierdenale (von Buch) 157,158, 165, 167, 170, 17.5, J9J var. commune Hyatt 165-168, 291, retardum Hyatt 160. note; 290 roemeri (Cragin) 172, 177 serpcntinum (Cragin ) 162-164, 167, 171, S,90, S9S stolleyi Bohm 157, 175, 29S, SOO subjcctum Hyatt 58. 161, 164, 168-171, 291,, -296 uddeni (Cragin) 1.54, 158, 159-161, 175, 290 Engonoceratidse 144, 145, 153-187, 193, 243 Erymnoeeras 102 Eulophoceras Hyatt 83-85, 100 natalcnse Hyatt 86-87, 271, Eulophoceratidic 24, 83-S7 Families, clas.sifled list of 15-18 Gabbioceras batcsi (Gahb ) 102 Genera, classified list of 1.5-18 PagB. Gerhardtia Hyatt 129, 130, 134, 135-136 galcatoides ( Karsten) 13.5 galeatus (Karsten) 136 veleziensis Hyatt 136 GloUoceras attenuatiLm Hyatt 151,1.52 Goniatitinte 21,74,102 Heinzia Sayn 101, 110, 117, 122, 128-130, 133, 135-137 corioli Xickles 1 30 heinzi Coquand 1 30 hispnnica Hyatt 131 matura Hyatt 116, 122, 128, 132-133, 2S2 ouachen.sis (Coquand ) 133 ouachcnus .Sayn 142 provincialis (d'Orbigny)... 117, 131-132, 133-136, 2«S,2M pulchelliformis Hyatt 131.132 sayni Hyatt 130 Heinziidfe 117.12S-136 Hemi tissotia Peron 35, 36, 38 batnensis Peron 39 caziui Peron 39 ceadouroensis Choffat 40 djelfensis ( Peron) 40, 54 morreni (Coquand) 39, 40 prsecipua 41 tissotiseformis Peron 40 Heterotissotia Peron 55 neocera tites Peron 55-56 Hoplites 101; 130,note: 193 hoplitiformis 131, note splendens 192, 193 Hoplitid* 105; 131, note: 137,192 Horizons, table of 18 Hyperlioceras discoidum 19 subdiscoidum 19 Hystatoceratidse 24, 26, 27 Indoceras Noetling 56 acutodorsatum ( Noetling) 57 baluchistanense Noetling 56-57 Knemiceras Bcihm 26, 30, 145, 192 attenuatum (Hyatt) 33, 151, 152, 2S6 compressum Hyatt 149-150, 152, 2SU var. subcompressum Hyatt 149, 150-151, 25i gabbi Hyatt lb2,2SS syriacum (von Buch) 146-149, 150, 2« uhligi (Choflat) 152 Knemiceratida; 144-152 Lenticeras Gerhardt 84-85.103 andii 84-85 Lenticeratidse 24 Leptocampyli 25 Libyeoceras Hyatt 56, 57 ismaele (Zittel) 58 Lophobolites Hyatt 41, 137, 144 cotteaui (Nickljs) 144 Mammitida 24,27; 101, note; 109 Mammitidie 24 Mantelliceras Hyatt 110, 111, 113 oouloni (d'Orbigny) 114 domeykanum (Bayle and Coquand) 115 indianense Hyatt 115 mantelli (Sowerby) 111,113,114 picteti Hyatt 114 ushas ( Stoliczka) 115 vicinale (Stoliczka) 115 Mantelliccratida 105 Mantelliccratida: 105-116,141 Metacanthoplites rhotomagensis (Defrauce) 107 INDEX. 349 Page. Metasigaloceras Hyatt 106 rusticum (Sowerby) 106 Metatissotia Hyatt 43, 4o. 50, 55 auressensis (Peron) 49 ewaldi (von Buch) 48,52 fourneli iBayle) 45,48 haplophylla { Redtenbacher) 48 nodosa Hyatt 4fi, 47, 48 robini (Thiolli^rei 45, 46-47, 4S slizewiczi (Fallot) 49 Metengonoceras Hyatt 153-155, 158, 170, 179-180 acutum Hyatt 184-185, 187, 304, SOS ambiguutn Hyatt 18S-1S4, SOi dumbli (Cragin) 180,185-187.306' inscriptum Hyatt 180-183. 184, 185, SOi, SOi Metoicocera.s Hyatt 101, 110, 113. 116-117, 129, 134 acceleratum Hyatt 127-128, iSO gibbosum Hyatt 121-12-2, 3S-' kanabense Hyatt SSS swallovi (Shumard) 117, 1 18-131, 122, 123, 134, 274, 27S, 3S2 whitei Hyatt 118, 121, 122-127, 128, i7S, iSO Metoicoceratidae 115-128 Mojsisoviesia Steinmann 24-25, 26, 27, 89, 90 dnrfeldi Steinmann 25-26, j?5i Mojsisovicsiidse Hyatt 24 Neolobites Fischer 68, 104, 144, 158, 178 choflati Hyatt 178,302 cnttfani Xicklt^s 144 peroni Hyatt 179 vibrayeanus (d'Orbigny) 178, 179 Neumayria 20 aspidoides 19 discus 19 hochstetteri 19 serrodens 19 Nicklesia Hyatt 136,137,138,140 alicantensis Hyatt 138 bertrandl ( Sickli'S) 138 didayana (d'Orbigny) 131,138 dumasiana (d'Orbigny) 138, 139, 2S6 karsieni ( I'hlig) 138 lapparenti (Nickl^s) 138 lenHculata (Hyatt) 188 levyi ( SicklOs) 138 malladEc (XicklOs) 138 moltoi (Nickles) 138 nolani (Nickles) 138 pulcbella (d'Orbigny) 141 zeilleri (Nickles) 138 Odontoceras 105 Olcostephanus 102 Orthoceratites \ 68 Oxynoticeras 104 heteroplcurum Neumayr and Uhlig 89-90 pseudogranianum Chlig 90 Pachyeampyli 25 Pachydiseus 90, 102 Paralenticeras Hyatt 84, note; 85 sieversi Gerbardt 85 Paratlssotia Hyatt 41,45,50,65,143 djelfensis 50 ficheuri (Grossouvre) 40,50,51,52 fourneli Grossouvre 52 grossouvrei (Peron) 49,50,54 regularis Hyatt .50. 53-54, iSS .serrata (Hyatt) 51-53.. 54, s,5« tbomasi ( Peron) ,50 Page. Pedioceras Gerhardt 105, 1 08 caquesensis 107 cundinamarcEe Gerhardt 107 ubaquensis 107 Pedioceratidge 105 Peroniceratidse 24, 27 Phricodoeeras 105 Phyllocampyli 25 Phylloceras 76, 88, 234 Phylloceratidaj 100; 101, note Placenticeras Meek 20, 22, 94, 140, 145, 153, 155, 178, 185, 188-196, 243, 244 californicum 192, note crassatum Hyatt 241 depressum Hyatt 190, 237 ebrayi (de Loriol ) 234-235 fallax Castillo and Aguilera 234 J'litschi Grossouvre 240 grossouvrei Hyatt 190, 191, 237-238 guadalupae ( Roemer) 188-191. 196- 197-199. 200, 202-204: 206, note; 211, 213, 237, SIO iucisum Hyatt 238 intercalare Sleek 190, 196, '205, 206, 207-21 1 , 214-216, 221, .^22-330 lentieutare Meek 71-75, 242 Warriensf Whiteaves 127,128 memoria-scbloenbachi Laube and Bruder 236 milleri (Hauer) 190,191,238,239 ne-vvberryi Hyatt 190, 191,196, '200, 203-205, '206,314 orbiguyanum (Geinitz) 240 pacificum 192, note placenta (Dekay) 190; 191, note; 196, 20'2, 209, 210, 211-214, 215-219, 221-223, 225, 233, 236, SSO, 333 placenta var. intercalare Meek 207 planum Hyatt 190, 191, 196, 202-203, 204, 211, 518, SSO polyopsis (Dujardin) 240-241 pseudoplacenta Hyatt 189, 190, 196, '214, 216-217. -232, 333, ,340 var, occidentale Hyatt 217-220,342 pseudorbignyanum Hyatt 240. 242 requieniauum d'Orbigny 236 sancarlosense Hyatt .... 191. 190, 200, 202, '206, 211, 312. Sli var. pseudosyrtale Hyatt 190, 191, 197, 199, 200-202. SIO, SIS schliitcri Hyatt 230, 239, '241, 242 spillmani Hyatt 233, 346 stantoni Hyatt 189, 190, 196, 214, 217, 218, '233, 236 var. boUi Hyatt 207, 212, 21 4-2 16, 219, 225, 226, SS3-3S8 sublilistriatum Jimbo 242 syrtale (Morton) '22,189-191, 196, 198, 200, 201, 203, '204, 205-206, 20.8-213, 215, 217, 220, 221, 232, 233, 236-239, 242, SOr,. 308 var. halei Hyatt 205, 206-207 syrtale var. qtiadralum Grossouvre '237 tamulicum (Blanford) '236.241-242 telifer (Morton) 233-234 nhliyi Choffat 1.52, 199, 235 warthi Kossmat 235-236 wbitfieldi Hyatt 22,189,190; 191 . note: 196, 208, 209, 211-220, 221-232, 236, 342-346' var. tuberculatum Hyatt 209, 214, '220, 2'21, 232 Placenticeratidte 188-245 Platylenticeras Hyatt 84, note; 85, 88-89. '245 gevriliauum (d'Orljigny) 84,90 heteropleurum (Neumayr and Uhlig) 89-90,99.244 pseudograsianum (Uhlig ) 89, 90 350 INDEX. Page. Plesiotissotia 34, 41 michaleti Peron 41 Polvplcctus oapellinus 19 iliscoides 19 Primordialida- 224 Prioniitropiflic 24, 27 Prolecanites 74 Protengonoceras Hyatt 20, 153, 157, 158, 179, 181, 186, 188, 189, 192, 198, 204 emarginatum (Cragin) 154,157,176 gabW (Bohin) 15:5-156, 176. ««6 planum Hyatt 156-157, f«S Pseudaspidoceras Hyatt 106-107, 116 coiieiliatum (Stoliczka) 107 crassitesta (Stoliczka) 107 cunliffi (Stoliczka) 107 dcciduum Hyatt 107 eiiomphalum (Sharpe) 107 footcanum (Stoliczka) 106, 109 schliiteri Hyatt 107 Pseudoceratites, definition of 13 Pseudophyllites Kossmat 25 Pseudotissotia Peron 34, 35^36, 37, 38 Imrjonai Clioffat 37 douviUci Peron 38 galliennei (d'Orbigny) 35,86,37.42 meslei Peron 37 tunisiensis Hyatt 36-37 Pseudotissotiidfe Hyatt 24,34-35 Psiloceras 24, 25 PsiloceratidsE' 25 Psilopulchellia 136,137,142,143 Psilotissotia Hyatt 41, 137, 140, 141, 143 clialmasi (NicklSs) 143 defforgesi (Sickles) 143 haugi (NicklSs) 143,144 mariolse (NickWs) 143 reigi (Nickl^s) 143 Pulrhellia Uhlig 41. 55, 112, 117, 129, 131, 136, 137, 139, 140-142, 144 eaicedi ( Karsten ) 130, 135 changarnieri Sayn 142 Columbiana 142 compres«issiina (d'Orbigny) 141. 142. 2« curioli Nickles 130 defTorgesi Nickles 143 didayi Gerhardt 136 /ouqiiri Nickles 139 hnugi 143 hdnzi Sayn 130 bet tncri 142 K-nrftini Uhlig 138 kiliani 133,142 nicklesi Hyatt 142 ocMerti NieklOs 139 outtchen.'ds Sayn 133, 142 provinciaUs d'Orbigny 129, 130, 131, 134 pidehdla d'Orbigny . . : 138, 140, 141 ^auvarifaui Hermite 139, 140 schlumbergeri NicklOs 142 selecta Gerhardt 142 Kidicaicali Sayn 1-29, 130 I'ulchelliida; 30,101; 104, note; 117,129,136-145 Ketardation in development 20-23, 189-190 Uoemeroceras Hyatt 26, 80, 36, 112, 145, 192 attenuatnm (Hyatt) S3,«M denticulatum 34 Page. Eoemeroceras Hyatt— Continued. gabbi Hyatt 30,31,256 subplanum Hyatt 84, 25S syriaciforme Hyatt 30, 31-32, 33, 34, 37, gSU Scaphites 189 Schlocnbachia 191, 193 Schluetericeras Hyatt 110-111 laubei Hyatt Ill michelobense Ill nodosoides (Schliiter) 110,111 vielbanci (d'Orbigny) 110 Sharpeiceras Hyatt Ill inconstans (Sehluter) 111,112 laticlavium ( Sharpe j Ill, li;> schlueteri Hyatt Ill Sigaloceras taylori 106 ■ Species, classified list of 15-18 Specific diflerences, absence of, in Placenticeras 196 Sphenodiscidae '24, 56-83 Sphenodiscus Meek 39, 51-57, 58, 83, 87, 91-95, 149, 163, 160, 180, 195, 233 aeutodormtu$ Noetling 57 acutum 58 beecheriHyatt 69, 78-82, 264, S70 helvidcrcnsis var. 8erpe7Umus Cragin 162. 164 hclvideren^is var. udden i Cragin 159 binckhorsti Biihm .58. 82 daMbll Cragin 185 cmarginatus Cragin 157. 177 isnuuliit Zittel'. 58 konincki Hyatt 82,2?6 lenticularis (Owen) 57, 58, 66, 70, 71-75, 77-82, 94, 95, S68, 270 var. magniflcus 76 var. mississippiensis Hyatt 77-78, 80, 81, 270 var. splendens Hyatt 75-77. 79, 80, SOS lobatus (Tuomey) ... 65, 66-70, 71, 75, 76, 80, 82, 264, 2«6, 470 pleurisepta (Conrad) 57, 58, 59-65, 70, 71, 75, 82, 258, g60. 262, 264 requimi Grossouvre 100 rocmeri Cragin 177 rutoti Grossouvre 83 Siva (Forbes) 88 stantoni Hyatt 70-7 1 , 81, 362, 264 iibagsbi Grossouvre 82. 83 Stepheoceras 102 Stepheoceratidte 102 Steuroccras Cossman 105 Stoliczkaia IW, note; 137, 140, 141 tetnigona Neumayr Ill Styracoccras Hyatt 83, 88, 244 balduri (Keyserling) 89. 244-245 Subpulchellia Hyatt 136, 137, lSfl-140 castellanensis Hyatt 140. 2*." touquei (NicklOs) 139 oehlerti (Sickles) 139 sauvageaui (Hermite) 139,140 Subtisscitia Hyatt 38, 42. 43. 45 afrieana (Peron) ■*■* inflata (Peron) 43.45 intermedia (Peron) 43-44. 4.-» percmi Hyatt ** Tachygcnesis 22. 23 Tegoceras Hyatt 83, 84 mosense 84, 87 Terminologv employed 11-14 Tissotia Douvill^ 32,35,36,38,41,42,45,55,104,178 INDEX. 351 Tissotia DouvilM— Continued. Page. (^ricana Peron 44 aure^ensis Peron 49 cossoni Peron 64-55 djelfensis Peron 40 ewaldi ( von Buch ) 44, 45, 46, 48 Jicheu ri Grossouvre 51 fourneli Peron 36, 45, 49 globosa Hyatt 55 grossou vni Peron 50 haplopfiylta Grossouvre 47, 48 Ifevigala 44 ri/bhii Gros^onvre 4-1. -16 Tissotia Douville— Continued. Page. serrata 192 slizcuiczi Grosfouvre 49 tkomasi Peron 50, 55 tissoti (Bayle) 35, 36, 42, 43, 52 Tissotiida- Hyatt 24, 26, 30, 34, 35, 41-56, 84 Tolypeceras Hyatt 101, note; 103-104 marcousanum 103-104 Traneceras 25 Vascooeras Choffat 101-102 hartti (Hyatt) 103,^50 subconciliatum Choffat 101 o PUBLICATIONS OF UNITED STATES GEOLOGICAL SURVEY. [Mon.ograph XLIV.] The serial publications of the United States Geological Survey consist of (1) Annual Reports. (-2) Monographs, (3) Professional Papers, (-i) Bulletins. 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