Neh one hey at ad ath! wh SeActoshath-virebsip edad, ahs wrinG ahialoaten Sele ekot on Pee RN MAAR ETN am Ped gt ourliamicr ee en Foe bho. Ke ote to Bosh do tnt to ae Manto 4... bar moh ma vig, WA Rio aE Mi ek yn Fle Cee Ty aie ~ IN em tS Ow + Fa cine Eel ee ee ee SS aT, ai atemthatis phe tnuiatby We” ate Balm hata Pet ate teen Sat ae ‘ean PO ND atta, my . TENE Tet oe ty Cat eyyhnn we Se RENIN R shorni ta we pees + wh te : » ~ hate aah Fs ee NR ct eM Grneete, a, Oh ce Ye tm, om nett aii ee a - A te ae Mikel oath iat, eat Hw Rie ST ty en “fie? ne eli Cae are a on Nah men gtnens - SAT eee TN at Sicthy A aig Meta” oP ed a oe ae te mothe Meany i ae Ee ene ‘ eed 2 PCa on aa ee oe Nees ey SE oe ge MOET ow ivgtoa 2 Tete ter, ee ee tee A ge gm SST PI ete hy ear Ne Reda mee. ee er Sa a AMe Pun tht Ph retort ae ae, Nie tO Pe The ew ay sete ae, woe Tele heh= ate clerteinie teh Ee ee BAS Songte eeree, oe eh Mew: iene cae wee na th mig shina me Se op me eee Se et ™ gia: Pose Netee hearer a TPR Hel eg SPER ae eS he wis a oe J hele whee Late san alban etn be maa lle! we ones ees Te Soke ne Sine wie C * > me fet ) el ¥ Saale a p ex : Pare eo ‘on eS %, a stil se i ith vig a ra nag alin st nes a Ee f SET) haf pore SO ae Len wt ne Lemme ALM rine ~> in ~S a fey fg tats Li AP ey wn ii See ies ie Pint So Fits, Aan NN fee, “poh ai, ae a o whan re flNe ae o. Taig hse On Sees raga 4 ic gar au oR # yy * i ‘ 4 eee seneeeets i ~~ Nee ay Airy, ky Bae ree a rE Roth aL) x ie a t: eh Aq x Be (e 3 eet Bs ; ewe, Plt er) ait ant je on CS fie oe cee Og eee B Me DE Wig ts Bigs Oe r i He ebay HEE roe THE AMERICAN JOURNAL OF SCIENCE. Epiror: EDWARD S. DANA. ASSOCIATE EDITORS PROFESSORS WILLIAM M. DAVIS anp REGINALD A. DALY, OF CAMBRIDGE, Proressors HORACE L. WELLS, CHARLES SCHUCHERT, HERBERT E. GREGORY, WESLEY R. COE anp FREDERICK KE. BEACH, or New Haven, Proressorn EDWARD W. BERRY, or BAurimorge, Drs. FREDERICK L. RANSOME anpb WILLIAM Deas oF WASHINGTON. FIFTH SERIES Xl@tional must VOL. IL-[WHOLE NUMBER, COII). — WITH PLATE I. NEW HAVEN, CONNECTICUT. I 2s Wes ee Ah i Be sh & PETA ASE ATPOL teen ing am ie a3 ays ALY an | 2 MBNA iB 2A Pde ee FE bea COD. FoRdea ua xe yr ae ea i AV REE We PONG ATE AHS Fea wb 1 EA Rs i SLokEt wad tea RAAT VE iia BETO ee gay ; = Ms P Vv t, Pe ae? . | ane Tih AA bi Boe) hi et, ~ ae THE mer MOREHOUSE & TAYLOR COMPAN ‘NEW HAVEN, CONN, i CONTENTS TO VOLUME IL. Number 7 Page Arr. I. —Relation of Isostasy to Uplift and Subsidence; by TWAT a): MESON s1a at nl Oa vr on om e 1. Arr. II.—New se aie in the Marsh Collection; by E. L. “1 RONCINIL Lie Aah EGS ey tra PgR Gor ok Ste a a 21 Art. IIIT.—New Species of Hyracodon; by E. L. Troxret,.. 34 Arr. IV.—Cenopus, the Ancestral Rhinoceros ; by E. L. TO TENO SCID I0 trig La MIMI peP ll Ratha sevtaecri tg ect TOGee MPG Meee an ROL Ra nen eh 41 SCIENTIFIC INTELLIGENCE Chemistry and Physics.—A Recaleulation of the Atomic Weights, F. W- CLARKE, 51.—The Fundamental Processes of Dye Chemistry, H. E. Fierz- Davin: Organic Chemistry for the Laboratory, W. A. Noyss: Quali- tative Chemical Analysis, M. C. SneeEp, 52.—Factory Chemistry, W. H. Hawkes, 53.—Neon Lamps for Stroboscopic Work, F. W. Asuron, 54.— Harmonies in the Siren, EK. A. Mitnz and R. H. FowuEr, 55.—An Intro- duction to Technical Electricity, S. G. STARLING, 956. Geology.— Thirteenth Annual Report, Florida State Geological Survey, H. GunteER, 56.—The Fossil Crinoid Genus Dolatocrinus and its Allies, F. SPRINGER; A Contribution to the Description of the Fauna of the Trenton Group, P. H. Raymonp: The Genesee Conodouts, with Descriptions of New Species, W. L. Bryant: The Trigoniz from the Pacific Coast of North America, Ff. L. PACKARD, 07.—Iowa Geological Survey, Annual Report, 1916: Ninth Biennial Report of the Commissioners of the Connecticut Geological Survey, H. E. GReGory: The Tin Resources of the British Empire, N. M. PEnzER, 58. Miscellaneous Scientific Intelligence.—Symbiosis, A Socio-Physiological Study of Evolution, H. REINHEIMER: Die Mneme als erhaltendes Prinzip im Wechsel des organischen Geschehens, R. Semon: Bibliotheca Chemica- Mathematica, 59.—Bibliotheca Zoologica II, O. TAscHENBERG: Annual Report of the Field Muse um of Natural History for the year 1920, D. C. Davies, 60. Obituary.—E. B. Rosa, 60. iV CONTENTS Number 8. Page Arr. V.—Llanoria, the Paleozcic Land Area in Louisiana and Hastern ‘Texas; by 1) (D. Mismr. 2... --2 aoe 61 Arr. VI.—A Fossil Flora from the Puente Formation of the Monterey Group; by R. W. CHAanny. 02): 230. 90 Arr. VII.—John Day Eporeodons, with Descriptions of New Genera and Species; by M. R. THorps............ 93 Arr. VIII.—Two New Forms of Agriocherus; by M. R. THORPE. (22 cas wlaeec. Ro ee eee ee let Art. [X.—The Crystalline Characters of Calcium Carbide; by7C. | TE OW AR REN C5: 90000) ve eee 120 CONTENTS Vv Number 9. Page Art. X.—Some Mechanical Curiosities connected with the iarth’s' Field of Horce;.by W. D. LAMBERT. ..%.. 22... .129 Art. XI.—Fauna of the Dallas Sand Pits; by R. 8. Lurr.. .159 Arr. XII.—Dirca palustris L., A morphological study; by se A ESL CLE Ace eed waltgil ate SGM Pea 8 EM cn A AE 177 Arr. XIII.—A Pseudocycas from British Columbia ; by E. NY “LEDTRITEST RS gee Lace AMA aa de OE RGIS RA a eR 183 vl | CONTENTS Number 10. Page Arr. XIV.—Further Remarks on the Evolution of Geologic Climates; by FE’. H. KNowLton:. ..25.. 0.2. 3350, eee 187 Arr. XV.—A Study of Diceratherium and the Diceratheres; by B.L. TROXEDLL: () tock heen ae eee 197 Art. XVI.—Fossil Vertebrates and the Cretaceous-Tertiary Problem; by WD. Marranwi7).2..6..5. 20 See 209 SCIENTIFIC INTELLIGENCE. Chemistry and Physics. — The Estimation of Sodium Hydrosulphite, J. H. SmitH: The Calculations of Analytical Chemistry, EK. H. MILuEer, 227. — Ammonia and the Nitrides, E. B. Maxrep, 228. — A Course in General Chemistry, W. McPHerson and W. EH. HENDERSON: Introduction to Quali- tative Chemical Analysis (Fresenius), C. A. MitcHEeLL: Diaphragms Capa- ble of Continuous Tuning, 229. — Philosophy and the New Physics, L. RovuGiEeR, 250. — The Chemical Effects of Alpha Particles and Electrons, S.C. Linn, 231.—The Copernicus of Antiquity, T. L. Heats: Mathematik in der Natur, H. Emon, 282. Geology. — The Circulation of the Earth’s Crust, EH, A. TANDy, 232. — A Re- print of the more inaccessible paleontological Writings of Robert John Lechmere Guppy, G. D. Harris, etc.: Grundztige der Palacontologie (Paléozoologie), K. A. v. ZITTEL and F. BRo1.1, 235. Miscellaneous Scientific Intelligence.—Carnegie Foundation for the Advance- ment of Teaching: Training for the public Profession of the Law, 236. — Publications of the College of Agriculture of Cornell University, Ithaca, N. Y.: Congress of Applied Chemistry, 237. — Personnel Relation in In- dustry, A. M. Simons, 238. CONTENTS vant Number 11. Arr. XVII.—The Crystal Structure of Alabandite (MnS) ; loge PANNE Gr NNEMOIOEE:. Gite cratntiae a deeded nelee } 239 Arr. XVIII.—Later Cenozoic Mammalian Remains from the Meadow Valley Region, Southeastern Nevada ; IDF Cro RO CI eg igs oe SME ays eapetnlecelt en pee OLN Ge hear arta a 250 Art. XIX.—The Classification of Igneous Rocks—A Study HO students: oyulis Vio PIRSSON, 42) 2 oa eelbies cues 265 Art. XX.— Studies in the Cyperacee; by Tuxo. Horm. Carices aeorastachye: Orinite nob., Apertz nob., and Magnifice nob. (With 8 figures drawn from MACON DME. AULMOM as Noah ss ysl ee kes tinue ale 3 285 Arr. XXI. —The Stratigraphy of Eastern New Mexico—a Wommcctlonr: Wy ie mee MOL yi ee eee eye Sos 295 SCIENTIFIC INTELLIGENCE. Chemistry and Physics.—A New Reaction for Ammonia, and its Application for the detection of Nitrogen in Organic Substances, C. D. ZENGHELIS, 298. —The Quantitative Separation of Arsenic, Antimony and Tin, F. L. Haun and P. Puinippr, 299.— Chemical Reactions and their Equations, I. W. D. Hacky: Food Products, Their Source, Chemistry and Use, E. H. S. BaILeEy: Discussion of Isotopes, 300.—Wireless Telegraphy and Telephony, L. B. Turner, 302. Geology.—The White River Badlands, C. C. O?Harra, 303.—Some Anticlines of Routt County, Colorado, R. D. CRawrorp, K. M. Wituson, and V. C. PmRINI: Permian Salt Deposits of the South-central United States, N. H. Darton: Interrelations of the Fossil Fuels, J.J. Stevenson: Foraminifera of the Philippine and adjacent Seas, J. A. CuSaman, 304.— The Direction of Human Evolution, H. G. ConKiin, 300.—Wissenschaftliche Forschungs- berichte; Naturwissenschaftliche Reihe, Bd. II, Ailgemeine Geologie und Stratigraphie, A. Born: Mineralogische Tabellen, P. Grors and K. MIE- LEITNER: Lehrbuch der Mineralogie (G. Tschermak), F. Becks, 306. Miscellaneous Scientific Intelligence.—Hlements of Map Projection with Appli- cations to Map. and Chart Construction, C. H. Deutz, 306. — Secrets of Karth and Sea, R. Lankester, 307. — Observations on the Living Gastro- pods of New England, E. S. Morse: Elements of Bond Investment, A. M. SAKOLSKI, 308. Vill CONTENTS Number 12 Page Arr. XXIJI.—A Newly Mounted Eporeodon ; by M. R. Tsorpre. . (With:Plate I)... oi, ....... 309 Arr. XXIII.—A Note on the Wedge Work of Pebbles; by C..K. WENTWORTH: : .i5:.22 70, 1908) 1.00 errr 313 Art. XXIV.—On Concentric Drag-Folding in Alabama Marble; by TV N:) DaLE®, fo 522. 20. ee Art. XXV.—Studies in the Cyperaceer; by T. Hom. XXXII. Carices aeorastachye: Phacote nob., and Ternarie nob. (With 11 figures drawn from nature. by the author)... 1. v2 ee aed. | oe S28. Arr. XXVI.—Native Antimony from ict County, Cali- | fornia; by C:'H. Bauru, Jr: 22... .0.6 2 ee 330 Art. XX VII—A New Merycoidodon; by M. R. Tuorpz... .334 Art. XX VIII.—The History of Corals and the ‘‘Limeless’ ‘ Ocean; by P. E. RAYMOND......:...7..0) 5.5) 52 343 SCLEN TELEICUINTELLAGEN CE: Chemistry and Physics.—A Rapid Process for the Determination of Phosphoric Acid, H. Copeau: The Existence of Tetrahydrated Sodium Sulphate in Mix-Crystals with Sodium Chromate, T. W. RicHarps and W. B. MELpD- RuM, 348.—A Textbook of Organic Chemistry, J. S. CHAMBERLAIN : Quan- titative Chemical Analysis, H. B. Targsor, 349.—Volumetric Analysis for Students of Pharmaceutical and General Chemistry, C. H. HAMPSHIRE: Etalon Interferometer: The Wehnelt Interrupter, F. H. Newman, 350.— Within the Atom, J. Minus, 301.—Mathematies for Students of Agri- culture, S. E. Rasor, 352. Geology.—The Rift Valleys and Geology of East Africa, J. W. GREGORY, 353.— The Fish Fauna of the California Tertiary, D. S. JornpAn: The Jurassic Ammonite Fanna of Cuba, MARrJoRIE O’CONNELL, 354.—A Text-book of Geology, A. W. GraBau: Het Idjen-Hoogland. Monographie II, De Geo- logie en Geomorphologie van den Idgen, G. L. L. KEMMERLING, 356.—Het Gouvernement Celebes, Proeve eener Monographie, L. vAN VUUREN: Moseunderségelser i det Norddéstliche Sjaelland, K. JEessmen, 356.—The Study of Geological Maps, GERTRUDE L. ELLEs, 357.—Geological Explo- rations in Africa, 358. Miscellaneous Scientific Intelligence.—National Academy of Sciences: American Association for the Advancement of Science: The Zoological Record, 1915- 1920, 358.—The Echinoderm Fauna cf Torres Strait, Its Composition and Its Origin, H. L. Charx, 359.—Readings in Evolution; Genetics and Eugenics, H. H. Newman: Philosophie des Organischen, H. DrreEscH: A New Alaska Base Map, 360.— The Geography of Illinois, D. C. RIDGLEY: La Géographie, 361.—A new map of the Pacific, 362. Obituary.—J. W. SPENCER, 363.—J. A. ALLEN: V. von Lane: J. von Hann, M. A. GRANDIDIER: A. S. F, LEIGHTON: S. S. VOORHEES, 364. INDEX: 365. JULY, 1921 Established by BENJAMIN SILLIMAN in 1818. | . THE AMERICAN j OURNAL OF SCIEN CE. Eprror: EDWARD S. DANA. ASSOCIATE EDITORS Prorussors WILLIAM M. DAVIS anp REGINALD A. DALY, oF CAMBRIDGE, | Prormssors HOR! GE L. WELLS, CHARLES SCHUCHERT, HERBERT 1. GREGORY, WESLEY R. COE anv FREDERICK E. BEACH, or New Haven, eee See ec * Proressor EDWARD W. BERRY, or BAuTimore, | Drs. FREDERICK L. RANSOME anpb WILLIAM BOWIE, oF WASHINGTON. “Tsu ittal (NS te, cS eas FIFTH SERIES ‘ ek VOL. H—({WHOLE NUMBER, “ost: | be oie Woe 7 fULY 1991. NEW HAVEN, CONNECTICUT. be Seal - THE TUTTLE, MOREHOUSE & TAYLOR CO., PRINTERS, 123 TEMPLE STREET. ‘dollars per year, in advance. $6.40 to countries in the ‘Single numbers 50 cents; No. 271, one dollar, he Foes Office at N ew ‘Haven, 1, Conn. prtex the Act Not ow , Ready METALLURGY OF THE COMMON \ETALS : Fifth Edition, Revised and Enlarged By LEONARD S. AUSTIN, formerly Professor of Metallurgy and Ore Dress- a Ae ing, Michigan College of Mines. This Fifth Edition has been largely rewritten to bring it in accord with |} * present practice in the metallurgy of the common metals (gold, silver, iron, jj- = copper, lead and zinc). A chapter devoted to questions of the economic situate of the business of e : a8 _ metallurgy is included, dealing with the rapid advance in price and the con- |} Sequent serious modification of the costs of operation. a “METALLURGY OF THE COMMON Meer: has 615 pages, 6 by 9 inebes, and 1 - : 178 figures. It is bound in cloth — price, $7.00 postpaid. coe = “PATTERSON'S FRENCH-ENGLISH | DICTIONARY FOR CHEMISTS — By AUSTIN M. PaTTERSON, Ph.D., former ly Editor of ‘‘Chemical Abstracts. ss This Prehen English Dictionary has been written as the result of many — e 2 requests for a vocabulary along the same lines as the author’s very Sule Es tes German- English Dictionar y. Over 32 ,000 definitions are given. ae 403 pages, 5 by 7, flexibly bound PATTERSON'S GERMAN-ENGLISH - DICTIONARY FOR CHEMISTS By Austin M. Patrerson, Ph.D. $5.00 postpaid. - Over 30,000 definitions are given, including terms from all branches of | pases Chemistry and the various chemical industries. 3 332 pages, 5 by 7 inches, flexibly bound $2.50 postpaid. Send for- Free Examination copies of these books. JOHN WILEY & SONS, Inc. | 432 Fourth Avenue, New York ceed London: Chapman & Hall, Ltd. : —Ag8-7-21 THE AMERICAN JOURNAL OF SCIENCE [FIFTH SERIES.] o> Arr. 1—The Relation of Isostasy to Uplift and Sub- sidence;! by Wiiu1am Bowrs, Chief, Division of Geodesy, U. S. Coast and Geodetic Survey. Introduction. There are many phases of the subject of isostasy, any one of which would make the subject of a paper of an hour. In going over the question as to what I should talk about to-night, I reached the conclusion that it would be better not to tire you with details of the observations and compu- tations involved in the isostatic investigations but to show, in a general way, what are the data, what is their reliability and what are the logical conclusions which _ may be drawn from the results of the investigations. ‘The figure of the earth. We should first consider the shape and size of the earth before we can understand how geodetic observations furnish data for the study of the distribution of densities in what Bailey Willis has very aptly called the ‘‘isostatie ~ shell.’’ ; If the earth were not rotating and its materials were homogeneous with respect to depth, the actual surface of the earth would be a.true sphere. The earth is rotating and, therefore, the combination of the gravitational force and the centrifugal force would make this ideal earth have a surface which would be a spheroid of revolution. As a matter of fact, the densities, at least in the outer a read before the Geological Club of Yale University, February 10, Am, JOUR, Poe Series, Vou. II, No. 7.—Jury, 1921. 2 W. Bowie—Relation of Isostasy to portion of the earth, are heterogeneous and our spheroid of revolution which depended on the assumption of normal densities, will depart somewhat from this mathematical surface. The mountain masses and the deficiency of mass in the ocean volumes will cause the actual water surface to be higher or lower than the mean surface which we shall call the spheroid of revolution. It would be well to conceive of sea-level canals cat int the existing areas of the earth. The surface of the oceans and of the waters in these canals will form a figure of equilibrium which we eall the geoid. The deviation to this imaginary surface over land areas from the mean spheroid of revolution will be a maximum of possibly 100 meters. This maximum occurs under the great mountain masses. ‘he fundamental problem of the geodesists is to deter- mine the shape and size of the mean sea-level surface of the earth and the deviations from this mean surface of the geoid or water-level surface. The only way in which to determine the shape and size of the earth is by means of astronomic observations which are connected. by triangu- lation or direct measurements. The shape, but not the size, can also be obtained from gravity measurements. Deflection of the vertical. Some years ago, when attempts were made to determine the figure of the earth, it was found that the direction of the plumb line at the astronomie stations was materially affected by the masses above sea-level and the deficiencies of mass in the ocean areas. Corrections were applied to the deflections of the vertical for the positive and nega- tive attractions of these masses, but then it was found that the directions of the corrected plumb lines had anomales of opposite sign to those which obtained before what might be called the topographic corrections had been applied. It is easily seen that if we should have a spheroid of revolution without any local disturbing influences, three or four latitude stations, somewhat widely separated along a meridian. with triangulation connecting them, would furnish us data from which to compute the elements of the ellipse, which would be the meridiona! section of the spheroid. Owing to the irregularity of the actual surface of the earth, the problem is not so simple, and Uplift and Subsidence. 2 we must extend our data over large areas in order to eliminate the local effects of the topography. The theory of tsostasy. Some years ago the idea was advanced that a mountain mass had under it a deficiency of material that was prac- tically equal in amount to the mass of the mountain and that under an ocean area there was an excess of matter equal in amount to the deficiency of material in the ocean. — This balancing of the mountains and oceans by deficiency and excess of material, respectively, in the outer portion of the earth was termed isostasy by Major C. H. Dutton. No comprehensive tests of this theory were made until the early part of this century when Prof. John IF’. Hayford made his splendid investigation in the figure of the earth and isostasy. There were many papers written on the subject of isostasy prior to Hayford’s work, among the most important being those by Putnam and Gilbert. The fundamental principle of isostasy is that, at some depth below sea level, the pressure on equal areas is the same throughout the earth. Hayford adopted this prin- ciple but it was necessary for him to make other assump- tions in order to carry on his investigations. His assumptions were, first, that isostasy is confined to a certain definite zone, with a uniform limiting depth, which he termed the depth of compensation; second, that the compensation is complete, that is, that it exactly equals in amount the excess or deficiency at the surface; third, that the compensation is uniformly distributed with respect to depth; and, fourth, that the compensation is directly under the topographic feature. Hayford did not believe that these assumptions are strictly true but he thought them to be as logical as any other simple assump- tions which are necessary to be made in order that the vast amount of computations may be undertaken. Let us get a clear idea of how the topography and com- pensation are used in the determination of the figure of th earth. We must correct the astronomic observations in order to eliminate the local attraction of the topography and the compensation, and after these corrections have been applied we have data from which to determine the lengths of degrees of longitude and latitude, at various P Appendix 1, U S. Coast and Geodetic Survey Report for 1894; and vol. 13, Bulletin, Washington Philosophical Society. 4 W. Bowie—Relation of Isostasy to places within the area where the observations have been made. It is not necessary for us here to go into details of the determination of the figure of the earth for they can be consulted in articles which are easily accessible. But let us see what we do at a single astronomic station. Let it be supposed that we have a mountain mass close ~ to the astronomic station, say within 100 miles. This mountain mass will have an attractive effect on a particle at the astronomic station. As a result of this attraction the plumb line to which all astronomic observations are referred will be deflected towards the mountain. It isa simple matter to compute this effect and apply it to the observed latitude and longitude. We next compute the effect of the isostatic compensation of the mountain mass and apply this as a correction to the latitude and longi- tude. We actually have many mountain masses which must be taken into consideration for each astronomic station. What we use in our final data are the resultant effects of all of the topographic features, whether land or water, within 2564 miles of the station, together with their isostatic compensation. 7 Investigations of the effect of isostasy on the deflection of the } vertical. When Hayford had corrected all of his astronomic stations, more than 500 in number, he made a mathema- tical solution of the results from which he derived the dimensions of the spheroid of revolution and the depth of compensation. The most probable depth for the United States from the data available was found to be 122 kilo- meters. A depth obtained previously by Hayford from fewer data was 113.7 kilometers. It is very interesting to note that the depths differ about 8 kilometers, which is quite a large per cent of the depth itself. Hayford found from his investigations that the result- ant deflections of the vertical after the effect of topog- raphy and isostatic compensation had been applied were, on the average, about one-tenth of what they would have been if the earth were rigid and there were no isostatic compensation. Investigations of the effect of isostasy on the intensity of gravity. After Hayford had completed his investigations of the figure of the earth and isostasy he began a second inves- Uplift ‘and Subsidence. 5 tigation in the subject of gravity and isostasy. Shortly after he began this he severed his connection with the Coast and Geodetic Survey and for a short time the inves- tigation was conducted by Dr. Hayford and the writer, and later by the writer alone. The investigations in gravity and isostasy confirmed the results obtained by Hayford from the investigations of the figure of the earth and isostasy. Isostasy was found to be in about as complete a state from the gravity investigations as from the figure of the earth investiga- tions.. The depth of compensation computed from the eravity investigations was found to be approximately 96 kilometers. This agrees with Hayford’s determination of the depth of compensation from the figure of the earth investigations when he used only data in mountain regions. ‘The depth of 96 kilometers was obtained by the writer from gravity stations in areas of high relief. It is not necessary to go into details in regard to the compu- tation of the depth of compensation, but when we consider the fact that a dise of material, of uniform density and thickness and of infinite horizontal extent, has the same attraction on a particle, regardless of the distance of this particle from it, we can see that it is difficult to obtain a value for the depth of compensation in a flat area, such as the coastal plain or a plateau. The determination of the depth from data in mountain regions is very much more sensitive. Reliability of geodetic data. Some question has been raised at various times as to the reliability of the geodetic data. It is safe to assert that the accidental and systematic errors in the astro- nomic observations, in the triangulation, and in the pendulum observations are so small that they need not worry us at all. For instance, if we should say that the observed deflection of the vertical is 5”.5 in the meridian or in the prime vertical, it is reasonably certain that its error 1s not greater than 0”.5. Similarly, if the gravity observations give an intensity of 980.025 dynes, it is practically certain that this value is correct within three or four in the last place of decimals. No one will doubt but that these degrees of accuracy are well within the limit* desirable in geodetic investigations. Published reports on the investigations of the figure of the earth and 6 W. Bowie—Relation of Isostasy to of gravity consider, in some detail, the question of the accuracy of the data. As to the question of the reliability of the computations of the effect of isostatic compensation we have a different proposition. In the first place, we may say that as far as the mathematical work is concerned the results are reliable and accurate, but the effect of the compensation will vary somewhat depending on the assumptions made. It should be pointed out that the effect of the compensa- tion will be approximately the same for all methods of distribution, vertically, which have the center of gravity of the compensation approximately 50 kilometers below the surface of the earth. Methods of distribution which deviate materially from this condition will not give as accordant results as those based upon this requirement. Umform distribution of compensation vertically. — We should consider here the question of distribution of the isostatic compensation with respect to depth. Uniform distribution appears to the geodesist to be a logical or reasonable assumption, for, in the first place, the geodesist is not. supposed to know anything about the geology of the isostatic shell, except in so far as information may develop from geodetic investigations. — It seems probable that, if one had never heard of isostatic compensation and he was told that a mountain mass or a plateau is balanced by a deficiency of mass in a column directly under the topographic feature and that this compensating deficiency extends to a certain definite depth, he would conclude that the deficiency of mass is distributed uniformly throughout the column. He would see no reason why compensation should be greater in one part of the column than in another, although one would be apt to believe that the compensation ends gradually rather than abruptly at the lower end of the column. We could distribute the compensation in any one of a number of ways, with respect to depth, and still have the center of gravity of the compensation approximately at 00 kilometers. But who is to decide and upon what data is the decision to be made as to what the actual distri- bution is, that is, the one that is in accordance with the truth? $ _As a matter of fact, the writer believes that compensa- tion varies in its distribution, vertically, from place to Uplift and Subsidence. 7 place, but that the average distribution for any large area such as that of the United States approximates uniform distribution. One can see that, if we took the mean of all possible distributions, approximately uniform distribution would result. Distribution of compensation horizontally. An attempt was made by the writer to show whether it was better to have the distribution of the compensation directly under the topographic feature or to have it distri- buted regionally within certain limits of distance from the station. The evidence seems to be strong that the distri-_ bution could not be extended to as great a distance as 100 miles in all directions from the station, but that results as accordant, or nearly so, were obtained when the distribution was extended about 40 miles in all direc- tions from the topographic feature as when the compen- sation was assumed to be loeal. Effect of ignoring compensation for small areas. An attempt was made to show whether gravity anoma- lies could be more nearly eliminated if we assumed that local areas near gravity stations did not have their topo- graphic features compensated. Computations of the effect of the isostatic compensation out to distances of 18 miles and 36 miles in all directions from gravity stations were made. These effects were subtracted from the total effect of compensation of all topography. The results indicated most clearly that the gravity anomalies were largely increased by this method, showing conclusively that we cannot ignore the compen- sation of the topography for even small areas. Of course, we may ignore the isostatic compensation of the topog- raphy near a station where the relief is very low. But the tests were made for stations having elevations greater than 1000 meters (about 3300 feet). Relation between isostatic anomalies and topography. Tests have been made to show whether there is any relation between the sign and size of the gravity anomalies and the character of the topography. No such relation has been found for the isostatic anomalies but decided relations have been noticed for the anomalies obtained 8 W. Bowie—Relation of Isostasy to by the two older methods of correcting gravity observa- tions. One of these is the Bouguer method, based on the theory that the earth is rigid and that the topographic features are actual excesses or deficiencies of mass sup- ported by the earth. The other is the free-air method of reduction in which no account whatever is taken of the topography and the isostatic compensation. It is the same as if we assumed that the topographic features were compensated for at zero depth. Of course this is an artificial method but it was adopted in order to reduce | some of the anomalies by the Bouguer method. Anomalies greatly reduced by considermmg isostasy. The investigations of the figure of the earth and isos- tasy showed that the topographic features were compen- sated to such an extent that the residuals or the unexplained deflections of the vertical were only one-tenth of what they would have been if the earth had been rigid. Therefore, we may assume that the columns from the surface down to the depth of compensation are compen- sated within approximately ten per cent of the topog- raphy at the top of the column, in some cases land above sea-level and in others deficiency of matter in the oceans. An attempt was made to show what reduction has been made in the gravity anomalies as a result of applying the isostatic theory. Two methods were employed. One considered the effect of the topography for the whole world and the other considered the effect of the topog- raphy out to a distance of approximately 100 miles from the stations. By the first method, it 1s found that the isostatic gravity anomalhes are only 17 per cent of what they would be with a rigid earth. By the second method, the average isostatic gravity anomaly was found to be only about 138 per cent of what would be the average anomaly on the rigid earth. In the first test, all stations of the country were used, whether at high elevations or at low ones, but the data for the effect of the topography on the opposite side of the earth from the station were not as reliable as we should have liked them to be. This is due to the fact that the data for the effect of topography and compensation for the very distant areas were not computed separately but in combination. In the second test, only stations having an elevation greater than 2000 feet were used, and Uplift and Subsidence. 9 we considered the topography out to about 100 miles. The topography for 100 miles farther has httle or no effect on the station because of the great distance and the fact that the topography is nearly in the same horizon as the station, thus making the vertical component very small. We may conclude, I think, that the second method gives the better result. By it the average gravity ano- maly is about 13 per cent of what it would be on a rigid earth. This is so close to the ten per cent obtained by Hayford as the relation between the isostatic deflection and the rigid deflection that I shall, in the remainder of this paper, adopt ten per cent as the relation between isostatic and rigid anomalies, both deflection and gravity. Relation between isostatic anomalies and areas of erosion. It has been found that there is no definite relation between the sign and size of the isostatic gravity anomaly and areas of erosion. There may, of course, be areas of erosion where the gravity anomaly tends to be negative or to be positive, but we may say that no definite relations ean be found that are general in their application. Relation between isostatic anomalies and recent geological formations. We have found a.very definite relation between areas of recent sedimentation and gravity isostatic anomalies, and this definite relation applies to stations on all the sub-divisions of the Cenozoic formation.. For a number of years the negative gravity results along the coasts and in inland areas of recent sedimen- tation were thought to be an indication of a lack of isos- tatic equilibrium in those areas. It was early found, in the investigations by the writer, that there is a definite relation in sign between the gravity anomalies and the. Cenozoic formation. In the report*® on gravity investi- gations, published in 1917, the writer arrived at the conclusion that the Cenozoic anomalies were negative because the material of this formation, extending some distance below sea-level, is much lighter than normal. In most cases it is probably more than 10 per cent less than normal. It is apparent that if we have very light * Investigations of gravity and isostasy, spec. publ. 40, U. S. Coast and Geodetic Survey, 1917. 10 W. Bowie—Relation of Isostasy to material close to the station, its attractive effect will be less than if we should have material of normal density occupying the same space. This opinion of the writer was accepted by Col. Burrard, former Superintendant of the Trigonometrical Survey of India. He has recently published a very important book dealing with this subject, entitled ‘‘Investigations in Himalayan and Neighbouring Regions’’ (Professional Paper No. 17, Trigonometrical Survey of India, 1917 Sup. 285, February 1921 of this Journal). The writer had stated that possibly the columns under the Cenozoic formation are in isostatic equilibrium, for it is inconceivable that the load of sedi- mentation added to the column should make it have less material than normal. Col. Burrard made computations to show whether the idea of isostatic equilibrium of the columns under sedimentary areas is a reasonable one. He concluded that the negative gravity anomalies can be eaused by the presence of Cenozoic material near the gravity stations -and that, probably, the Indo-Gangetic plain is in isostatic equilibrium. Relation between isostatic anomalies and the Pre-Cambrian formation. | The writer has found that there is a very definite rela- tion between the sign of the gravity anomaly and the Pre-Cambrian formation. Here we can account for the positive character of these anomalies by the presence of extra heavy material close to the gravity stations which is probably compensated for by a deficiency in the column below. Ishall not take time to discuss the Pre-Cambrian formation and its relation to the gravity anomalies, but I have dwelt upon the relation of the gravity anomalies to the Cenozoic formation because it is important in throwing light on some phases of mountain formation. The datum used for isostatic investigations. A subject that I should lke to discuss at some length is the datum used for computations of the effect of topog- raphy and compensation, but I shall not take the time to do so here, because of more important phases of isostasy that must be considered. I may say that it makes very little difference in the conclusions arrived at from isos- tatic investigations whether we use some other datum than mean sea-level for the computation of the effect of Uplift and Subsidence. 11 topography and isostatic compensation. I simply raise the point here because attempts have been made to show that the isostatic results are made somewhat unreliable by some other datum not having been adopted. ‘The principal reason why this subject should be considered is that the question of the percentage of completeness of compensation is involved in it. You will notice that I have not previously made any statement in regard to the percentage of completeness of compensation. I have simply shown that the isostatic reductions reduce the ano- malies to a certain per cent of what they would be if the earth were rigid. It is difficult to interpret the results in terms of mass. The actual distribution of compensation cannot be proved mathematically. The statement was made by McMillan, in his article on the ‘‘Hypothesis of Isostasy’’ (Journal of Geology, February-March, 1917), that ) ‘‘From a purely mathematical point of view any set of a finite number of observations of the intensity and direction of gravity ean be satisfied, not approximately, but exactly in infinitely many ways by a proper distribution of the density of the earth.’’ Speaking mathematically, this statement is justified, but any distribution of the densities in the earth that is not general in its application, which would exactly elimin- ate the anomalies of the deflections of the vertical and of the intensity of gravity, would be so artificial as not to be at all reasonable. It seems to be logical to assume that the only reasonable hypothesis regarding the distri- bution of the densities in the outer portion of the earth is one which will be very general in its application. We cannot accept methods of distribution which are designed simply to eliminate the anomaly by having one distribu- tion at one gravity station, another distribution for a second station, and so on throughout the list of stations. Prediction as a test of isostasy. _ The results of the investigation into the theory of isostasy have been very striking and this is brought out clearly in a recent article entitled ‘‘A Brief review of the evidence on which the theory of isostasy is based’’ by Col. 12 W. Bowie—Relation of Isostasy to Burrard (The Geographic Journal, Royal Geographic Society, London, July, 1920). Burrard shows that the isostatic method can be used to predict what the intensity of gravity or the deflection of the vertical will be before observations have been made. This prediction cannot be made with any degree of reliability if the condition of isostasy is ignored. The methods adopted by the geodesist can stand the test of prediction. Some other method, not yet formulated, may work equally well but it cannot depart materially from the one now in use. The density of material in the isostatic shell. It has been held by some that the geodesist assumes a density of 2.67 for the density of the material in the isos- tatic shell. Geodesists have never postulated the density of the material below sea-level, except in so far as attempts have been made to show that the presence of Cenozoic and Pre-Cambrian formations affect gravity anomalies. What the geodesists have done is to compute the deviations from normal densities in the column down to the depth of compensation. We may assume that the normal densities for the various zones are A,, As, As, ete. The geodesist computes the deviations from these unknown densities. The theory of isostasy is based on the idea that the mean density in a column times the volume of the column is a constant. Hach column is assumed to have the same cross section and to extend from the depth of com- pensation to the surface of the earth. The volume of the column and the density of the material are supposed to be normal under the coastal plains. The column under a mountain mass will be longer than normal, its volume will be greater and, there- fore, its density of material must be less. Under the oceans the column of material is shorter than normal, the volume will be less and the density of material will be greater. River deltas as a test of the strength of the earth’s crust. In his series of papers entitled ‘‘The Strength of the Earth’s Crust,’’ Barrell attempted to prove that the crust or isostatic shell is able to hold large masses as. extra loads, because it is able to hold up the sedimentary material deposited at the mouths of rivers. He used Uplift and Subsidence. | 13 the Niger and the Nile in his tests. He showed that the present configuration of the bottom of the ocean at the mouth of the Niger indicates that there is much material present in a space formerly occupied by water. He concluded that this material is an extra load and 1s a measure of the earth’s strength. It appears to the writer that we may have an explanation of the presence of this sedimentary material which will be consistent with the theory of isostasy and the view that the earth’s crust is not excessively strong. The apparent maximum depth of the sediments in the delta of the Niger is approximately 10,000 feet. The density of this material is probably about 2.4. The density of sea-water is slightly over 1.0. Therefore the weight of water displaced by sediments is approximately the weight of 40 per cent of the material deposited. There remain 6000 feet of sedimental material which Barrell claimed is the overload. If we should have a sinking of the sedimentary material in the isostatic shell, as we find has taken place in many parts of the earth, then we should expect to have some sediment above the former position of the bottom of the ocean. The sedimentary material is approximately 20 _per cent lighter than the material whose space it occupies _ and, therefore, as a thousand feet of sediment is deposited, we can expect 800 feet of this material to sink into the earth and 200 feet to stand out. We can explain the ten: thousand feet of material above the former ocean bed if the total thickness of sediments under the surface of the Niger delta is 34,000 feet. There would be 24,000 feet below the original position of the base of the sediments. This does not seem to be an excessive depth of sediment, judging from what has been found in other parts of the earth. _ Barrell has found a depth of 7000 feet of sedimentary material under the surface of the delta of the Nile. If we use the same reasoning in regard to the Nile delta as for the Niger, we shall require only 24,000 feet of sedi- ments to enable 7000 feet to project above the surface coinciding with the former bottom of the Mediterranean. A test of this theory that the delta formation is not an overload could be made by gravity observations. Unfor- tunately, we. have only one gravity station on a well- defined delta. This is at New Orleans, La. Here the 14 W. Bowie—Relation of Isostasy to eravity anomaly is — 0.018 dyne. This is certainly an indication that the Mississippi delta is not an overload, for if it were the anomaly would unquestionably be positive. The writer predicts that there will be a decided ten- dency for the isostatic gravity anomalies to be negative at delta stations. Contraction of column under sediments. In discussing the question of the delta formations, we assume that as the sediments are deposited, the surface of the sedimentary material gradually increases in eleva- tion. There are cases where this is not true, for we find - evidences of very thick sedimentary material, all of which was deposited in very shoal water. In such a case we have to assume that there must have taken place an increase in the density of the material of the column as sedimentation progressed. It is only by doing this that we can have a column under sedimentary material in equilibrium, because the material deposited is lighter than the material whose space it occupied. This change in density in the column is entirely apart from the isostatic adjustment. It must be due to some chemical or physical action of which we have no knowledge. It is possible that. the decrease in density in the material in the column with resulting subsidence of the surface began before sedimen- tation started and really decided the region in which sedimentation should occur. If we should have sediments to the depth of 40,000 feet, all deposited at about sea-level, and if the column were in equilibrium before sedimentation began, then we must have had an increase in the density of the material of the column and a consequent shrinking of the original material which is equivalent to about 8000 feet of sedi- mentary material. This sedimentary material is not above the sea-level surface and, as the sediments are not able to lower the former surface of the column except by their weight, we must assume that the space occupied by the 8000 feet of sedimentary material must have resulted from the contraction of the column. There undoubtedly is a small amount of contraction in the original material of the column, due to the pressure of the sedimentary material on the column, but this contraction would be a small percentage of the total contraction necessary to have Uplift and Subsidence. 15 all of the sedimentary material deposited close to sea- level. I have given the question of sedimentary areas consid- erable space in this paper because of its fundamental ’ importance to the theory of isostasy. If we can prove that the areas of sedimentation which have gravity ano- malies of a negative sign, often of large size, are in isos- tatic equilibrium, then we would be justified in concluding that we have local rather than regiona! isostatic adjust- ment and the earth’s isostatic shell would be shown to be far weaker than many are now willing to admit. The writer believes that we have proved that the large Ceno- zolc gravity anomalies are due to the presence of hght material close to the station and that we are justified in assuming that the columns under the Cenozoic material are In approximate isostatic equilibrium. Compensation exists under small areas having high relief. IT have not given space in this paper to a discussion of the gravity anomalies at stations on the Pre-Cambrian formation, but it is believed that the tendency of the anomalies at stations on that formation to have positive signs is an indication that the columns under the Pre- Cambrian may be in isostatic equilibrium. If we can eliminate or account for the anomalies on the Pre-Cam- brian and Cenozoic formations then we have taken a long step forward in proving that local isostasy exists. It is, of course, a question of how local the area may be that is in isostatic equilibrium. This is a question that cannot be mathematically solved but as isostatic investigations are extended the areas which may escape a high state of equilibrium (at least in elevated regions) become smaller and smaller. They appear to be well within 100 miles square in mountain areas. This question of the size of an area which may be in equilibrium has an important bearing on the question of mountain formations. Uplifted masses due to vertically rather than horizontally acting forces. From a consideration of the discussion above we may assert that columns under mountain masses and under areas of sedimentation are in equilibrium. Therefore, if a mountain mass is formed over a column which was subjected previously to heavy sedimentation, the moun- 16 W. Bowie—Relation of Isostasy to tain mass will not be an extra load on the column. It is evident that this is the ease, for the area of sedimentation must have been in isostatic adjustment or at least not lighter than normal, and we find that the mountain mass is not an extra load judging from the results of the inves- tigations of the deflections of the vertical and the gravity observations. | If this mountain mass is not an extra load, then it could not have been brought from some other area to the one it now occupies. If itis not an extra load, it could not be due to horizontal thrusts operating in the earth’s isos- tatic shell and extending far beyond the mountain areas. We are led to the conclusion that the cause of the moun- tain formation is a local one, and the only local cause seems to be a change in density in the column. This change must have been the result of a local expansion in the isostatic shell under the sedimentary material which was thrown up to form the mountain mass. In most cases the mountains are formed in areas where heavy sedimentation previously existed. The mountain mass is not a permanent feature on the face of the earth as is shown by the fact that areas that are now high were once at or below sea-level and other areas, which at one time were high, are now depressed. The mere fact that we have had this oscillation of the erust and that all types of topography in areas where geodetic investigations have been made are in equilibrium leads us to conclude that there has been, in the past, changes in density ina column. At one time the density would increase, at another decrease. It is not known just how these changes have been brought about but, in an area of sedimentation, the base of the sedimentary material may have been depressed as much as five miles. This would lead us to believe that all of the material below the base of the sediments down to the zone of isostatic flow had been depressed an equal amount and that the temperature of the material had been raised several hundred degrees Fahrenheit over what it was in its original position. The isogeotherms may be depressed with the sinking of the column and, after the sinking has ceased, the lines of equal temperature may rise to their normal positions. In any event, the material of the column has been depressed to hotter zones and probably chemical and a _— Uplift and Subsidence. 17 physical action has resulted, which may cause the expan- sion of the columns. ‘phere What is the cause of an increase in density in the column is, of course, not known, but when a column under a mountain mass is elevated as erosion takes place, we are bringing up material to colder zones than they formerly occupied and this may lead to some chemical or physical action which would contract the materials sufficiently to account for a depression of what was formerly a moun- tain area. | Horizontal movements may be mcidental to vertical uplift. There is abundant evidence that there have been hori- zontal forces at work distorting the sedimentary strata in a mountain area and we have evidence of overthrusts which extend for a number of miles. This, on first thought, might lead one to conclude that the mountain formation could not have resulted from vertically acting forces. The apparent answer to this objection seems to be that the base of the mountain system is usually large. The Appalachian system is approximately 200 miles wide, on an average. This appears to be a sufficiently large area to permit of development of horizontal move- ments incident to the uplift. It seems reasonable to suppose that the sedimentary material was of widely varying thicknesses, that it was laid down at different rates at different places and that the base of the sediments gave way at different places at different times and at different rates. No doubt the sedimentary strata were somewhat distorted in the process of subsidence. When uplift begins it is probable that it takes place in different sections of the area affected at different rates and at different times. There would be more resist- ance to the uplift in some parts of the area than in others. The isostatic shell just beyond the zone of uplift would undoubtedly have considerable effect on the upward motion of the materials of the column adjacent to its edges. It seems probable that the uplifted material would follow the line of least resistance and, at least near the surface, some of the lines followed by the material would be horizontal or nearly so. It is conceivable that in the process of uplift in a large area we should get distortions such as are found in most areas of mountain uplift. Am. Jour. Ses SERIES, VOL. II, No. 7.—Juty, 1921. 18 W. Bowie—Relation of Isostasy to We have evidence that much material of the earth has been uplifted without distortion. The great plateaus of the west have their strata practically horizontal and in some cases they extend for miles. These plateaus were originally at or below sea level and it is improbable that the material of the column of the isostatic shell under them was less dense than normal. Therefore, when they have been elevated, and the geodetic data prove that they are now in approximate equilibrium, we must conclude that no additional material has been added to the columns under the plateaus. Barrell recognized the necessity for having a decrease of density under the Colorado plateau. In the ‘‘Strength of the Earth’s Crust’’ he said: ‘‘Tt is known that a region like the Colorado plateau, which now stands markedly high, tended to lie near sea-level from the beginning of the Paleozoic to the end of the Mesozoic. Pre- sumably a decrease of density within the zone of isostatic com- pensation has taken place here during the Cenozoic and the uplift has accompanied or followed the internal change.”’ Great changes in elevation not due to isostatic adjustment. It must be clearly borne in mind that the theory of isostasy cannot explain great changes in elevation. There will, necessarily, be some changes in elevation which can be attributed to the theory of isostasy. These changes result from hghter material than normal being deposited and sinking to take the place of material of normal density. If no other action than isostatic adjustment acted in the column under the sediments we should expect . the surface of the sedimentary material to increase grad- ually in elevation. If, for instance, we had 30,000 feet of material deposited we should expect at least three thousand feet to project above the original position of the base of the sediments. As a matter of fact, it is probable that the elevation of the surface would be even higher than that, because the difference in density between the sedimentary material and material displaced by the sediments is undoubtedly greater than ten per cent. As erosion continues in a mountain area the surface should become gradually lower as the result of the isos- tatic adjustment. The reason for this is that material is brought into the column under the mountains heavier Uplift and Subsidence. 19 than the material that is eroded from the surface. If we should have 10,000 feet of material on the average eroded from the mountain mass, we should expect an equivalent mass of material to flow by isostatic adjustment into the column, probably at the base of the column. This material would, undoubtedly, be at least ten per cent heavier than the material eroded from the mountain. Therefore the mountain surface should be lowered at least 1000 feet, if 10,000 feet of material is eroded from it. ' Aside from these changes in the elevation, I do not know of any others which are caused by isostatic adjustment. They must be due to other causes which, I believe, are decreases and increases of density in the isostatic shell. They are not believed to be due to transference of material horizontally from one region to another. Of course, | am speaking here of comparatively large areas for we do have evidence of transference of material in local areas. Zone of horizontal movement. Barrell in the ‘‘Strength of the Harth’s Crust’’ pre- sented arguments in favor of a zone of weakness below the isostatic shell which he calls the asthenosphere. He held that the isostatic movement, horizontally, takes place in the asthenosphere. Willis agrees with Barrell on this point. The writer has no very clearly defined ideas on this subject, but he believes that the views of Barrell and Willis are reasonable and justifiable. ; If the earth’s crust were weak enough to permit isos- tatic adjustment to take place comparatively near the surface, then we should expect that the materials would be so weak that masses of different densities would tend to flatten out and adjust themselves in strata, each with a uniform density. That the isostatic compensation extends to considerable depth is an indication of a certain amount of resistance, horizontally, to movements. It seems probable, there- _ fore, that. the horizontal movements necessary to effect the isostatic adjustment take place below the isostatic Shell. Whether the flow is very deep seated or in the outer portions of the asthenosphere cannot, of course, be determined, but the writer believes that the flow takes place just below the isostatic shell, in the outer portion of the asthenosphere. 20 W. Bowite—Relation of Isostasy, etc. Topography compensates deficiency or excess im isostatic shell. Mr. R. D. Oldham, in discussing a paper® on isostasy presented before the Royal Geographic Society by Col. Burrard, emphasized the importance of stating clearly whether a mountain is compensated for by the defi- ciency of material in the column under it, or whether the mountain is a compensation of the light material of the column. Geodesists have spoken of compensating deficiencies of material under the continents and compen- sating excesses of material under the oceans, but it is the writer’s belief that the mountain masses and the defi- ciency of matter in the oceans compensate the abnormal conditions of density which exist in the columns under them. ° A Brief Review of the evidence on whieh the theory of isostasy is based. Geographic Journal, July, 1920, London. E. L. Troxell—Amynodonts in Marsh Collection. 21 Arr. IL—New Amynodonts in the Marsh Collection; by Enwarp L. TRoxE.. [Contributions from the Othniel Charles Marsh Publication Fund, Peabody Museum, Yale University, New Haven, Conn.] TABLE OF CONTENTS. The Amynodontide. Summary of species and relationships. Adaptations to physical environment and to feeding. Description of new species. Metamynodon rex, sp. nov. Amynodon erectus, sp. Nov. THE AMYNODONTID2. Summary of Species and Relationships. Orthocynodon Scott and Osborn (1882, p. 223), Amyno- don Marsh (1877, p. 251), and Metamynodon Scott and Osborn (1887, p. 164) constitute a group of rhinoceros-like ungulates found in America alone. Authors have placed Cadurcotherium in the family Amynodontide, apparently on the basis of the great premolar reduction, but this seems wholly inharmonious when we judge this genus from the figures of its teeth (Abel 1914, p. 239). Metamynodon planifrons Scott and Osborn and M. rez, sp. nov., come from the lower Oreodon beds, from a zone of river sandstones characterized by and named from the genus. Only two of these interesting specimens have been described and but few skulls are known to exist. The holotype of M. planifrons is in the Museum of Com- parative Zoology at Harvard University; it consists of a Skull and jaws. A fine complete skeleton in the Ameri- can Museum of Natural History has been fully described by Osborn (1898, pp. 80-94). The genus Amynodon is better known, because it is represented by several species: A. (Orthocynodon) anti- quus (Scott and Osborn) is found in the Middle Eocene or Washakie; A. advenus (Marsh) and A. intermedius Scott and Osborn, together with A. erectus, sp. nov., rep- resent the Uinta beds of the Upper Eocene, and are in general more advanced in their evolution. The Yale specimens come from the region of White River, Utah. * This is the first of a series of four articles on the rhinoceroses in the Marsh Collection; the three others deal in turn with Hyracodon, Cenopus, and Diceratherium. 92 HE. L. Troxell—Amynodonts m Marsh Collection. A. antiquus may be distinctly separated from the others, perhaps subgenerically, by the presence of both upper and lower functional first premolars, and by a marked difference in the general proportions of the teeth. The new species, A. erectus, is small and primitive, and in this respect approaches dA. antiquus, but it has lost all trace of the first premolars and is of a later geological horizon. A. intermedius, the largest and most progressive of the species, resembles Metamynodon in the form of its canines and molars and approaches it in the size of the teeth, and in the stage of the premolar reduction also, where the premolar series measures half the molar length. In progressing to the state of Metamynodon, an undoubted lineal successor, besides the shght further reduction of the premolars, we note the gradual lengthen- ing of the skull behind the orbits, the widening of the molar teeth, the tendency toward compleated folds on the premolars, the increase in the size of the canines, the closing of the external auditory meatus below, and the general crowding and concentrating of the hinder part of the skull near the condyles or fulcrum, this last made necessary by the enormous increase in weight of the skull as a whole. Adaptations to Physical Environment and to Feeding. Most of the characters which distinguish these animals from the true rhinoceroses are thought by Osborn, Scott, and others to be a response to the needs of a semi-aquatic life. This is borne out especially by the observations on (1) the posture of the naso-maxillary opening, governed by the short nasals; (2) the position and form of the -posterior nares; (3) the high, anterior position of the orbits; (4) the broad, spreading feet and their ability to fold backward; and (5) the great increase in size. The naso-maxillary opening, or anterior nares, which depends upon and at the same time determines the form of the nostrils, taken together with certain features to be discussed later, suggests a prehensile, or very mobile lip such as one sees in the hippopotamus and other water animals. The depth and position of the posterior nares seem to facilitate breathing, by making a closer connec- tion between the larynx and the nasal passages when the mouth is full of food or water; and further, they prevent - the entrance of foreign substances, water, etc., into the ee E..L. Troxeli—Amynodonts m Marsh Collection. 28 larynx and windpipe while the mouth is open under water as In the act of gathering food. An intimate connection of the epiglottis with the pharynx, as enclosed by the soft palate, is seen in the modern horse, where no passage of air is possible through the mouth in ordinary breathing. In this recent animal, it is thought to be a provision against breathing the dust from the grasses which constitute a greater part of its food.. There is a resemblance in the form of this opening in the amynodonts and in the horse. A further adaptation to a watery habitat is seen in the forward and high position of the orbits, which serves to keep the periscopic eyes out of the water for swimming or for observation while hiding; this finds its greatest devel- opment in Hippopotamus, in which the orbits actually rise above the plane of the face, and here also, as well as in Metamynodon, we find the broad spreading feet suited for walking on the softer ground near and in rivers and lakes—feet which are so constructed that the toes fold together backward as they are lifted and carried forward through the resisting water. | In speaking of the hippopotamus, Roosevelt and Heller say that the semi-aquatic habits have favored its develop- ment to an enormous bulk. This is no doubt true of Metamynodon also, and while locomotion would be diffi- eult and clumsy on the land, it would be greatly facili- tated by the buoyancy of water even if the beast were only partly submerged. : : In both the genera of the Amynodontide the skulls show fosse in the roof of the mouth, the purpose of which is problematical; but together with the deep antorbital depressions, they certainly constricted the nasal passages to a considerable degree and must have interfered with ae organs of smell—of minor importance to an aquatic east. | The following points may be interpreted as evidence of a prehensile lip at least in Metamynodon: (1) the rough- ened supra-orbital ridges, together with the conspicuous tubercles just in front of the eyes, and (2) the large cheek depressions, possibly indicative of large face muscles; (3) the moderately large infra-orbital foramina, doubled in the holotype of A. erectus, and required in order to furnish plentiful nourishment and nerves to the facial organs; and finally (4) the nature of the narial opening 24 E. L. Troxell—Amynodonts in Marsh Collection. which, especially in Metamynodon, is triangular in form, broad above and constricted below, and situated well back on the maxillaries, due to the abbreviated nasal bones. We may judge further of the living conditions of the Amynodontide by the character of the teeth. The canines and molars have developed with the skull and are larger than those of any other rhinoceros of the period, but the incisors and premolars have not kept pace and are scarcely larger than in Amynodon, showing but slight need for cutting teeth in these animals. The upper eanines of Metamynodon and of A. intermedius were strongly procumbent and diverging; they were not erect in the jaw like the canines of Archeotherwm. The molars are broad and flat and in their use must have been comparable to those of an elephant, serving to grind up the food secured by the canines; this may have consisted of bark, tuberous roots, nuts, or leaves, gathered near the aquatic haunts, in the mastication of which the molars were used, leaving no need for premolars of the cutting type. | There seems to be little wear relatively on the narrow premolars; most of it comes on the middle of the cheek _ series, on M! especially. There is naturally less wear on M? which appears last, though on this molar one sees the vestigial extension of the ectoloph beyond its junction with the metaloph, which serves to prolong the period of usefulness of the tooth by furnishing a longer grinding surface. In comparing these metamynodonts with the other groups of rhinoceroses of the period, we see that Cenopus and Diceratherium developed their molars more like the horses, 1. e., for grazing, had sharper edges on the ectoloph for cutting the food, and the premolars were much more eee and more molariform than in any of the amyno- donts. DESCRIPTION OF NEW SPECIES. Metamynodon rex, sp. nov. (Figs. 1, 2.) Holotype, Cat. No. 10274, Y. P. M. Lower Oligocene (Metamynodon zone), Pine Ridge Agency, South Dakota. This fine specimen was purchased from Mr. C. H. Little E. L. Troxell—Amynodonts in Marsh Collection. 25 of South Dakota in 1889 by Professor Marsh; only recently has it been freed from the stony matrix and identified. Skull characters —The malar-temporal suture begins in the orbit; the zygomatic arch is concave internally in both directions and is very broad. ‘The strong sagittal crest rises an inch or more above the cranium. The posterior nares lie entirely behind the last molar, with the opening very deep and well guarded by the broad pterygoids. The wide spacious articular glenoid surface extends onto the heavy postglenoid process, which curves forward and away from the paramastoid to which it is closely joined. ‘The basicranial angle is large, a progres- sive character. The roof of the mouth is arched into a deep fossa between the premolars. There are deep cheek depressions, but they are restricted in area. The nasal bones are short. : 10274 TYPE RS S \ \\ \\ g << CW: SS =— aN SUN S aN ~: ; See TRAE (g SYUsre By SS p t ! h? S li\Ses Fic. 1.—Metamynodon rex, sp. nov. Holotype. Side view of skull of the ponderous aquatic rhinoceros. Note heavy zygomatic arch, deep facial pit, strong outward curving canine (restored), and short face. 1/6. Dentition.—The incisor teeth, absent here, are known to be small in the type of M. planifrons. A diastema of 3mm. separates the canine from P?. P! is obsolete. P? forms an irregular pentagon; it is probably three-rooted, and is made up of crests and ridges like the other premo- lars, but appears in its natural posture to have been rotated through an angle of 80 or 90 degrees; thus the protoloph and metaloph extend directly backward instead of transversely. P? is broad transversely and short antero-posteriorly, the diameters being 31 by 21mm. The ectoloph is broad and in the present state of wear occupies about half of the 26 FE. L. Troxell—Amynodonts 1m Marsh Collection. surface of the tooth; the metaloph is very narrow, joins the protoloph through the deuterocone, and surrounds a central lake across which there is a very narrow bridge or small fold of enamel. Because of the small metaloph and the receded position of the tetartocone, the worn sur- face of the tooth forms a triangle. P+ presents equally strange characters: it 1s extended transversely but is squeezed in between P? and M! so that it is longer on the inner side than along the ectoloph. The wide extension inward forms a gentle slope from the deuterocone, but more especially from the tetartocone to the cingulum. The metaloph is relatively larger than that of P® and widely separated from the protoloph. On the right tooth, a sharp ridge, on the left a low broad one, ay UE Go Md nN EE yh in AAAI a mm ‘ (OG aX “lf OR 7m 10274 TYPE Y.. PM, Fie. 2.—Metamynodon rex, sp. nov. Holotype. Palatal view of skull showing great reduction of premolars with P? rotated, deep posterior nares, heavy canine, and posterior extension of ectoloph on M*. x 1/6. unites the two inner cones. There is a sharp crista divid- ing the internal lake (medisinus), and numerous small folds on the metaloph represent the crochet. The outer wall of the ectoloph on each premolar shows a heavy central buttress set off by vertical grooves in front and behind; this represents the central protocone, with the tritocone and parastyle behind and in front respectively. , M'! is so worn that no characters remain except a faint cingulum on the outer side, together with a small E. L. Troxell—Amynodonts in Marsh Collection. 27 Jake or remnant of the diagonal medisinus. The tooth forms a parallelogram elongated transversely; its diame- ters are 87 and 55 mm. | M? has its back, inner, and front sides at right angles, but the outer side is an oblique line. The longest dimen- sions are, on the outside, 51 mm., and the front side, 60 mm. The medisinus forms a deep sharp groove, directed inward and then forward, uninterrupted by a cingular ridge or basal cusp on its outer end; the post- sinus is rather deep, with a sharp foldinward. M' and M? show no groove, at the present state of wear, separating the parastyle; thus the outer walls are smooth and flat. _ M?, however, shows this groove distinctly. in form, M? is very much like M?, but it has a narrower posterior side; it has the postsinus formed by the exten- sion of the ectoloph, so typical of the family and so differ- ent from all other Oligocene rhinoceroses. On this tooth the internal basal cingulum swings into the medisinus, partly filling the groove. The posterior cingulum is much lighter than that of Amynodon. In contrast to the pre- molars, there are no folds of enamel on the walls of the transverse crests, but the enamel of the molars is gener- ally thick and heavy. | A portion of the right ramus No. 120438 of a fossil rhinoceros may belong to a Metamynodon; the three teeth are probably P,, M...; they increase rapidly in size so that the M, is larger than that of any Oligocene rhino- ceros known to the writer. Its great length and high crown are very striking features. The small premolars and the probable lack of P,, perhaps of P,, lend weight to | the identification as Metamynodon. Summary of Metamynodon rex, sp. nov.—The main differences between the two species of Metamynodon may be summed up as follows: premolars of M. rex, sp. nov., only submolariform; the type has no postorbital promi- nence rising from the malar such as appears in M. plani- frons; the zygomatic suture either forms a sharp angle or leads from within the orbit; P? has three fangs instead of two. The much smaller molar length, relative to the premolar length, results partly from the greater age and wear, especially on M?. . 28 EH. L. Troxell—Amynodonts m Marsh Collection. Measurements. M. planifrons M. rex Scott & Osborn Holo- 1887. type mm mm. Skull, length, incisor to condyles ............. 550 520+ Width across qalches (20-2 oe eet seat 365 360 Kace, orbit to premaxallany, antes. ee ee seers: 170 2111 Cranium, ant, ob Orbit, tO OcClput aan eso. once 385 350 Molar-premolar series, leneth™: 27 --- .- e 225 202 Molar series leneth’ 20. eee ee ee 160 140 Premolar' series!“leneth "2272 eee eee eee 65 61 . Diameters of teeth : C+, ant posts. % eee a ee Pa: 30 28.6 Cis transverse tig ee ee ae 35 36 PS, anil Ostet). Ate Soeielt. 6 eee 25 23 Ds, APAMSVETSe yt eb all. td -laetertee. Os. cee 45 43.4 ME. antapost. orcospite et eee ol eee AT 36 Mis trans VenSe 42:2). pciyctarmene tee iee Bete cee 68 06 Me, ant pOSt. 22 «3:0 pee eee. «eee 60 58 MY, CANS VCYSC 2: tue ees: ss ee 64 60 Amynodon erectus, sp. Nov. (Figs. 3-6, 7b.) Holotype, Cat. No. 11453, Y. P. M. Upper Eocene (Uinta beds), White River, Utah. The type of this new species is the well preserved skull and jaws used by Professor Marsh in amplifying the de- scription of A. advenus (1877, p. 251), figured by him in Op EX ik 11453 TYPE Fic. 3.—Amynodon erectus, sp. nov. Holotype. Top of skull showing left side crushed forward. x 1/6. his work on the Dinocerata and used in the study of brain capacities in extinct mammals (1884, p. 62, fig. 72). The valuable internal cast of the cranium is still available for - E. L. Troxell—Amynodonts in Marsh Collection. 29 comparison and study. The specimen itself has been improved recently by further preparation and now becomes the holotype of a new species. The genus Amynodon is much smaller than Metamyno- don, and its skull has lighter parts, as shown by the zygo- matic arch, the occipital condyles, the proportions of the teeth, ete. Skull.—The posterior nares extend forward to the second molar, otherwise they resemble those of Metamy- nodon in form, in the depth of the opening, and in the prominence of the pterygoids. The external auditory meatus is open below in this genus, as shown by A. erectus, sp. NOV. The basicranial angle (17.5°) is lower than in Metamy- nodon (25°); this is considered a primitive character generally, but here the decrease is partly due to crushing. The premaxillary appears as a narrow strip, barely visible externally; the nasals fold down one third of the distance on the sides; they bear no horn rugosities such as are found in Colonoceras (Marsh 1884, p. 62). The deep antorbital depressions are rather broader and more open than in A. intermedius, where they are abrupt. ‘There are two suborbital foramina on the right side, through which the nerves and blood-vessels reached the face. The supra-orbital ridge is roughened, and tubercles extend over and in front of the orbits. Dentition.—There still remain the roots of the second and third upper incisors measuring about 9 mm. in diame- ter; the median incisor is broken away entirely. The canine alveolus measures 19 by 12mm. In all probability this tooth was not procumbent as in A. imtermedius, but was more like that of A. antiquus (Scott and Osborn 1883); its shape. and position can best be judged by the lower canine, which rises and curves backward almost as in Archeothervwm and is worn in a similar manner on the posterior side. From the canine to the second premo- lar there is a diastema of 23 mm. The total measurement of the premolars, 50 mm., equals half that of the true molars, 98 mm. They are therefore almost as reduced as are those of A. wmterme- dius, but that species includes its vestigial P', which is absent in the new species. It is seen from the wear on the lower teeth of A. antiquus also that P! was present. P* measures 31 by 19 mm.; the outline is well preserved and the worn enamel indicates a broad shelf on the —800—O#E. L. Troxell—Amynodonts in Marsh Collection. postero-internal corner. Remnants.of the internal lake indicate the presence of the two transverse crests as in other specimens. M* is subquadrate in form and is much shorter, antero-- posteriorly, than it is wide (27 by 38 mm.). M?* forms an irregular quadrilateral with the longest sides anterior (42 mm.) and exterior (43 mm.). The outer side of its ectoloph is apparently entirely smooth, the cingulum and the groove marking off a parastyle both being lost by wear. On M? and AL there are heavy posterior cingula inclosing depressions (postsinus) and the broad incon- spicuous antecrochets are set off by grooves extending down the protocones. M® has three sides at right angles, while the side of the ectoloph runs ona diagonal. The diameters are: antero- posterior, 36 mm., and transverse, 39 mm. The outer side of the tooth is divided into two areas, or grooves, by Fic. 4.—Amynodon erectus, sp. nov. Holotype. Side view of skull. x 1/6. a strong ridge opposite the paracone. There is a distinct parastyle. The continuation of the ectoloph beyond its union with the metaloph offers one of the distinguishing features of the Amynodontide. The postsinus is much deeper than that j in the holotype of A. advenus Marsh (Cat. No. 11763, Y. P. M., fig. 7). In the latter the cingular ridge does not inclose a depres- sion, anterior or posterior, nor does the cingulum extend across the end of the median valley. On the other hand, M? of A. erectus, sp. nov., in fact, each of the molars, has a strong cingulum anteriorly and a decided internal basal ridge extending across the medisinus which rises into a small cusp, as in certain diceratheres. | Lower jaws.—One ramus of the mandible is almost complete, including its dentition. The body is narrow EB. L. Troxell—Amynodonts m Marsh Collection. 31 and somewhat rounded, as in Equus; the horizontal por- tion is deep and strong, the ascending ramus is wide (cf. A. antiquus) and has a thick anterior border with a deep depression exteriorly. PME \ \ \ Pe Ka S/T \\\ SS Fic. 5.—Amynodon erectus, sp. nov. Holotype. Side view of lower jaws showing erect canines and reduced premolars. 1/6. The lower teeth of this new species are of especial interest, furnishing new features of Amynodon. The first lower incisor is largest, and is worn off squarely on the end like those of the horse, while the third incisor is smallest and shows the spatulate, subconical crown with a strong cingular ridge on the posterior side. M. plan- frons is said by Scott and Osborn (1887, p. 167) to reverse this order in the lower jaw, but to follow it in the upper incisors, a rather unusual thing. 7 The canine leaves the alveolar border directed for- ward but curves upward to an erect position. It 1s worn on the front side by the third upper incisor; more signifi- cant still, however, is the wear on the posterior side by the superior canine, which must therefore have been much more nearly erect than that of A. intermedius. It resem- bles in this respect A. antiquus, which is shown to have had an erect lower canine (Scott and Osborn 1883, pl. 5). The transverse diameter is 16 mm., the antero-posterior 18.5 mm. There is a diastema of about 35 mm. between C, and P,, P, being obsolete. The length of the series of three existing lower premo- lars is 45.7 mm., of the three molars. 97.4 mm. P.,, the first of the series, is small, conical, vestigial; it has two depressions on the inner side, and a basal ridge. P, is intermediate in size, but has a form similar to P,, which in turn is submolariform. 32 «FE. L. Troxell—Amynodonts in Marsh Collection. Most of the enamel is broken away from M,. It is slightly smaller than M,, which is similar in size and shape to M,. The last is but little worn and shows well the two erescentic ridges so characteristic of the rhinoceroses. Fic. 6.—Amynodon erectus, sp. noy. Holotype. Crown view of lower teeth.” C13. Summary of A. erectus, sp. nov.—The holotype is based on a very well preserved skull and jaws, more primitive than A. mtermedius, but more advanced than A. (Ortho- cynodon) antiquus. It is smaller than any of the other species. It presents evidence of erect canines both above and below, and in this respect resembles A. antiquus; from this species it differs, however, in its later geological age, smaller size, and especially in the absence of both upper and lower first premolars. ‘The holotype of A. advenus Marsh, Cat. No. 11763, Y. P. M., consists of a single third upper molar. A. erec- tus, sp. nov., may be distinguished from it by the stronger cingula both fore and aft, the deeper postsinus, the much narrower medisinus with a basal cingulum and cusp obstructing its opening, and finally, its smaller size. \\, \\' ZB \\ \ WN) WA | \ if Mil | KK “/) ( ‘\\ 1 ——s My) Fig. 7—a, Amynodon advenus Marsh. Holotype. Cat. No. 11763, Y. P.. M..b, A. erectus, sp. nov. ‘Holotype. Cat. No.’ 11453, Y.7 Pa ne Third upper molar of each species. Note the differences of size and form: the variation in the anterior and posterior cingulum, median val- ley, and internal basal cusp, and the ectoloph extended backward. Nat. size. E. L. Troxeli—Amynodonts in Marsh Collection. 33 Measurements of Holotypes. A. , A. erectus antiquus intermedius sp. nov. (Scott & Osborn) Osborn 1883 1890 mm. mm. mm. SableeMeneu heck eres eae Cee e 350 Length of molar-premolar series . 145 187 Length of molar series .......... 96 104 Diameters of upper teeth: ee OSU. Gi aes als bees Se 4 2s 20 22 ep CIISVICESE 5 s.6 Fe 6 ce ge. of sy6 use te o2 33 CEOS OCS gs ee 001i eee 28 37 44 WER rirAMSVerSe ls. Andee .teee dia... 39 at 43 DVI eratal A TOOSES bchts ARES ooo eel ww Se 37 45 a3 DMCA SEAMIG ENS 3. siya aie! gthopieyovs ccc skeen) 2 42 37 a2 ARCO eNOS ee cd. «foc Atv) os) say ola as 36 28 46 Pe AMG VERS C5. ac cee teen « 0)3 0 a's 38 30 46 Lower jaw: Iueneth, incisor to angle.......... 306 Width. body of mamuisn.. Ve. 022.4 45 Depth of ramus below M,........ 74 Length of premolar series........ 46 80 Length of molar-premolar series.. 142 Sere pyyulnonnty Wig. ot, ike a elapsienle dye 104 165 Leneth ot molar series. .sa/ei) oe 5.. 98 Diameters of lower teeth : PPM iMG WErSCM ML Ohhh DAE 13 9 Aine Vienser cy 1.5 egy ides LIL 10 OP aiie=posts ay. 2) fea. .fedssiecss 18 15 ol Diastema,-C, to premolar... . 2.1 34 40 eee AMG OOS Ge ahs 8 etarehs ae aieies dot swe 10 19 15 eae OSL Rhee Bos cls ek SRE oa e's » 15 23 21 epee OStes eee oy Ri eh 22 29 1 26rd PPA MIS VICESCW St. Cinio ils esd ess 16 17 18 MViMereRMGETOOSUL [et tiki fare SPAR (ia gc Ss, « « 29 37 30 Wie siraMSVEVSE Le oot Sk oe. eatisheea ae ge 24 22 MI ante post UA EU cee oi 34 ° 44 46 PIPE AIUSVERSE ooo so als gos es 0 23 : 24 Meira WOSi OL eien. aes. 38 AT? Me rir AIISWETSS cee YIN efile ier. eee 20 24 References. Abel, O. 1914. Die vorzeitlichen Saiugetiere. Jena. mt” onal F 1875. Notice of new Tertiary mammals. This Journal (3), 5 —1877. New vertebrate fossils. Ibid. (3), 14, 249-256. —1884. Dinocerata. Mon. U. 8. Geol. Survey, 10. Am. Jour, pry fa SERIES, VcL. II, No. 7.—Jtxy, 1921. 34 E. L. Troxell—New Species of Hyracodon. Osborn, H. F. 1890. The Mammalia of the Uinta basin. Pt. IJ, The Perissodactyla. “Trans. Amer. Philos. Soc., new ser., 16, 505-512, pl. 10. —1893. The rise of the Mammalia in North America. This Journal (3),. 46, 379-392, 448-466. —1898. The extinct rhinoceroses. Mem. Amer. Mus. Nat. Hist., vol. 1, 75-164. Scott, W. B., and Osborn, H. F. 1882. Orthocynodon, an animal related to the rhinoceros, from the Bridger Eocene. This Journal (3), 24, 223- 225. ; —1883. On the skull of the Eocene rhinoceros, Orthocynodon, and the rela- tion of this genus to other members of the group. Contrib. H. M. Mus. Geol. and Arch., Princeton College, Bull. 3. —1887. Preliminary account of the fossil mammals from the White River formation, contained in the Museum of Comparative Zoology. Bull. Mus. Comp. Zool., Harvard College, vol. 13, 151-171. Art. U1—New Species of Hyracodon; by Kpwarp L. TROXELL. | [Contributions from the Othniel Charles Marsh Publication Fund, Peabody Museum, Yale University, New Haven, Conn. | INTRODUCTION. Hyracodon, a genus of rhinoceros-like animals, is known only in the Oligocene. Because of the slender limbs, long neck, and relatively small skull, it was early characterized by Scott and Osborn as cursorial, and it is probable that these light-running ungulates held the place in the econ- omy of nature now filled by the antelope and others of the small ruminants. | Because of the already great reduction of the lateral toes, Hyracodon had reached a state of development almost equal to that of Protohippus, and, the race persist- ing, might well have become monodactylous, like the mod- ern horse. Four species of Hyracodon have been made known, only one of which has had figures accompanying the descrip- tion. Leidy in 1850 gave us the first information of these animals; his later drawings (1852, 1854) have shown a widely diversified group, therefore H. nebrascensis in its broadest sense may apply to almost any hyracodont, and the species is virtually synonymous with the genus. The other known species are: H. arcidens Cope, H. major Scott and Osborn, and ? H. planiceps Scott and Osborn. E. L. Troxell—New Species of Hyracodon. 35 DIScUSSION OF KNOWN SPECIES. Hyracodon nebrascensis (Leidy). ‘“ A species founded upon a great portion of the face, containing all the superior molar teeth; an inferior maxilla with six molars ; and three superior, apparently deciduous moiars. It is about the same size as the R. minutus of Cuvier. ‘‘Length of line of seven supe- rior molars 4 7/10 inches [119.4 mm.] Length of line of six inferior molars 4 2/10 inches [106.7 mm.] Breadth of jaws from the first superior true molar teeth of one side to the other 366 /lOmimekes (96s mim | It is evident from this and subsequent descriptions that Leidy did not limit himself to one single species, but included specimens with varied features. Hyracodon arcidens Cope. The holotype is primarily based on a maxillary with the premolars and M? of a very young animal. Cope says: ‘“The species is about the size of the H. nebrascensis, and differs in the form of the inner lobes of the molars and of the first premo- lar. All the molars have the outer longitudinal and inner transverse crests, the posterior short, the anterior much curved backward round it, and thus forming the inner boundary of the tooth-wall.’’ This is apparently the first true specific description we have of a hyracodont; it is obviously similar to certain phases of H. nebrascensis—it could hardly be otherwise —but applies to that distinctive group, moderate in size, which have the anterior crest much curved backward. Hyracodon major Scott and Osborn. The type of this species is a fairly complete skeleton in the Princeton Museum. The species description? is based on a fore foot and therefore can not be compared to the new species described later in this paper; unfortunately it does not give any tooth characters and so we know little more than the proportional size of the specimen. “Joseph Leidy, Proc. Acad. Nat. Sci. Phila., 5, 121, 1850. abl Cope, Pal Bulls Noy 1532) 1873. * W. B. Scott and H. F. Osborn, Bull. Mus. Comp. Zool., vol. 13, 170, 1887 36 E. L. Troxell—New Species of Hyracodon. The published measurements show this species to be a half larger than ‘‘H. nebrascensis’’; it even surpasses the large H. leidyanus, sp. nov. ? Hyracodon planiceps Scott and Osborn. This is a very large rhinoceroid which, by the authors,* is doubtfully referred to Hyracodon. DESCRIPTION OF NEW SPECIES. Hyracodon arcidens miumus, subsp. nov. 7 (Fie. 1.) Holotype, Cat. No. 11174, Y. P. M. Oligocene, Deadwood, South Dakota. The holotype consists of both maxillaries with all premolars in excellent preservation. It is evident that this is near the species Leidy first described in 1850, because the measurements are close; it corresponds in turn to the specimen figured in plate XII A, 1852° and {] tl Mii Ha ip Gy Fie. 1.—Upper premolars of Hyracodon arcidens mimus, subsp. nov. Holo- type. Cat. No. 11174, Y. P. M. x 3/4. Note especially the continuous internal loops, the criste, and the prominent deuterocone of P*. resembles the maxillary shown in plate XIV, figs. 4-6, 1854.6 Cope’s description of H. arcidens shows it to have the same sort of looping protoloph, but his slightly larger eee is not figured, so no close identification is pos- sible. A summary of the distinctive features is: strong crista on the larger premolars; protoloph joins the tetartocone and on P?* it completely encloses the thin straight meta- loph; deuterocone and tetartocone united in P+ but with a deep double groove on the outside; cingula completely *Scott and Osborn, op. cit., p. 171. * Joseph Leidy, in Owen’s ‘‘ Report of a geological survey of Wisconsin, Jowa, and Minnesota,’’ ete. * Joseph Leidy, Smithson. Cont. Knowl., vol. 6, art. 7. BL, Tromell—N ew Species of Hyracodon. 37 surrounding all teeth; deuterocone very prominent on P+ and set off by vertical grooves; this tooth is subtrian- gular. None of the premolars can be said to be molari- form. Hyracodon selenidens, sp. nov. (Fries. 2-3.) Holotype, Cat. No. 11173, Y. P. M. Middle Oligocene, Colorado. This new species of Hyracodon is especially notable for its small size and the crescentic form of the deutero- cone, hence the specific name. The holotype is about three fourths the size of H. leidyanus described later, and is therefore the smallest of the Oligocene rhinoceroses. The species possesses certain features typical of Cenopus of an entirely different family, indicating parallel or con- vergent evolution; the complete enveloping of the meta- loph by the protoloph, and the diminution of the former are seen in C. allus and reach an extreme in C. nanolo- phus, new forms described in a later paper of this series. NK Plo A SSNS Whe SE AWE Fic. 2.—Upper cheek teeth of Hyracodon selenidens, sp. nov. Holotype. Cat. No. 11173, Y. P. M. 3/4. The smaller cross crest is completely encircled by the other on the premolars of this very small species. \ 7 NUS Sa VN ‘ S \\ Kk & Pegi Maz: Fic. 3.—Lower molars and premolars of the small Hyracodon selenidens, . sp. nov. Holotype. x 3/4. P! departs from the pattern of the other premolars; its protoloph is scarcely more prominent than the cingu- lum posterior and is separated from the inner main cone; the metaloph bisects the tooth and ends in a cross on its outer end. The tooth forms roughly the half of an ellipse. 38 a. L. Troxell—New Species of Hyracodon. The anterior premolars increase rapidly in size and P? is a third wider than P!. P? is subquadrate, having three sides at right angles. On this tooth the protoloph exhib- its the prominence which in part characterizes the species. Its form, however, is not that of a perfect crescent, for it shows an irregular curve and a ridge or pillar where it joins the tetartocone. The metaloph is a thin straight wall dividing the equal-sized medi- and postfossettes. P® resembles P? in nearly every respect, but shows a ereater decrease in the size of the metaloph and a smoother crescent. On P* the deuterocone is set off by vertical grooves running up the sides; this cone shows a strong tendency to lean toward and to occupy the central portion of the tooth. The prominence of the base of the cone gives the tooth a somewhat triangular outline. There is a small crista on P? and a small crochet on the metaloph of P* near the tetartocone, partly separating a portion of the medifossette or valley. There is evidence of a faint crista on M?, but the crochet seen on other specimens is undeveloped. The antecrochet is not so conspicuous as in HH. leadyanus, Cat. No. 11169. The molars are smooth on their inner cones, and in gen- eral show extreme simplicity. The crowns are relatively low. Hyracodon leidyanus, sp. nov. (Fies. 4-5.) Holotype, Cat. No. 11169, paratype, Cat. No. 11168, Y. P. M. Middle or Lower Oligocene, Crow Buttes, South Dakota. The holotype of this species consists of a maxillary and ramus with tooth series P! to M? and P, to M,, inclusive. The paratype material includes two specimens; one may be a part of the holotype but that can not be demonstrated. The parts preserved are: second upper molar, atlas, vertebre, numerous toe bones, tibia, astragalus, navicular, _metatarsus, and broken parts of the caleaneum, radius, metacarpal III, another tibia, and a second metatarsus. The holotype is unusual in its large size, smooth teeth, molariform premolars, and high crowns, together with the following additional features: The protoloph of P? joins more intimately with the metaloph than with the ectoloph and is very much decreased in size. The meta- loph of P?, which is only submolariform, extends at right angles from the ectoloph and at its end hooks backward in E. L. Troxell—New Species of Hyracodon. 39 a way peculiar to Hyracodon alone. t a later stage of wear, the two inner lophs unite by a narrow bridge. On the molars and large premolars there are developed sharp eriste and crochets, a feature which is well known in the totally unrelated later rhinoceroses, where the medi- fossette in its extreme form becomes a lake. New char- acters like these seem generally to arise on the outer edges of the cusps, and then in the course of evolution appear gradually more deep-seated. They are therefore quickly worn away from the tooth of a more primitive type. Fig. 4-—Hyracodon leidyanus, sp. nov. Holotype. Cat. No. 11169, Y. P.M. x 3/4. In this large specimen the ridges of the premolars are parallel and the median valleys uninterrupted. ih << ZZ S SZ, 7 4 Lf Fig. 5.—Lower molars of Hyracodon leidyanus, sp. nov. Holytype. x %4. The antecrochet on M!? is very strong and a sharp vertical groove divides it from the protocone. ‘Two grooves thus mark off the protocone, while one appears to limit the hypocone. The cingular ridges do not cross the bases of the inner cones of the molars as they do the premolars. The lower cheek teeth, like the upper, are notable for their general simplicity, subdued cingula, high crowns, flat outer surface, and lack of angularity. In Hyracodon there is not a great difference in the height of the anterior and posterior lobes of the lower molars, as there is in Cenopus or even T'rigonias. In the lower jaw, an alveolus reveals the former pres- ence of P, or Dp,, which as a permanent tooth is seen in no other specimen of Hyracodon at hand, indicating in general the advanced evolution of this genus. : 40 E. L. Troxell—New Species of Hyracodon. The external vertical groove of the lower teeth curves backward in a way unlike that of any other specimen observed, and, especially in the two larger premolars, continues into the cingular ridge instead of ending abruptly against it. SUMMARY. There are three families of extinct rhinoceros-lke animals: the true Rhinocerotide, giving rise to our modern animals; the Amynodontide, culminating in Metamynodon in early Oligocene time; and finally, the Hyracodontide, represented by the single genus Hyraco- don, found in the Lower and Middle Oligocene of the Great Plains. This genus is easily distinguished by its small size, its slender proportions, and the presence of all canine and incisor teeth. The trend of its evolution seems to have been toward the loss of the lateral toes, a cursorial adaptation. Two new species and one subspecies have been estab- lished here in order to set forth features which either have ‘ been ill defined, or are entirely new in the genus. Measurements of Holotypes. 17 Ae fal a bs ~ mimus leidyanus selenidens Upper jaw: 100000 mim. mm. Premolar seriesmleneth (hates. 67 74 ain Molar premolar series, length ....... 129” 142* 110 | ey 2) OV Tage Selah ees WE BAS ay Wel an cee 13 14 i ACS Ar Ia Wiehe ari IN CREE oe OE 1 ale 12 Pa lengin Oise tthe peek eres 16 18 14 IW hag ee eee eee eee 19 21 16 P*, lemethest: elit See eee See 18 21 15 Wrchita 4 is SO 7 ee ee 2 25 19 P* ene tit 5.5 Fy. 55 | ea Se oe ee 20 22 16 Wii itl oe othe: ae es mien on eee 26 Pa 21 IMS lemotly .o.8 py, Gate ie en ee 24 19 Width Jil Rigel. {Cn gRe et src oat ee 4 PS) 21 ME lems pt. 3! tose $e'op bicnvines Aeposeeeee 27 20 OAGLGH. be Soa wee £4 em eens 27 21 Wes emotion stare, meme eee, a 17, Wierd Din? So eee ere eee eee ee ee 21 Lower jaw: Length of three premolars .......... 61 46 Length of three premolars and M, ... 85 63 Length of molar premolar series ..... 101 *Estimated. . E. L. Troxell—Cenopus, the Ancestral Rhinoceros. 41 Arr. IV.—Cenopus, the Ancestral Rhinoceros; by Epwarp L. TROXELL. [Contributions from the Othniel Charles Marsh Publication Fund, Peabody Museum, Yale University, New Haven, Conn. | INTRODUCTION. Until very recent times there were two great groups of extinct rhinoceroses mentioned in the literature, Acera- therium Kaup and Diceratherium Marsh, and specimens from Lower Oligocene to Middle or Upper Miocene, both in the Old and New World, were classified according to the nasal bones, whether or not they had rugose thicken- ings designed to support horns. Due to the work of Osborn, Scott, Loomis, Cook, and especially of Peterson, it now appears that the two classes are simply the hornless females and the horned males, of a variety of genera. There are, however, two important exceptions to this general rule: (1) the early Oligocene species which did not show the horn rugosities in the males, and (2) those recent animals (excepting Rhinoceros sondaicus) in which both males and females may have horns. _ Peterson shows that in Diceratherwm cooki the horns belonged to the mature males alone; the females and young males were hornless. In the Peabody Museum there are horned and hornless specimens of Diceratherwwm from the John Day beds of Oregon. The mature animals may be either, but the very young individuals always have smooth nasals. Osborn (1898) has demonstrated that Cenopus tridactylus also has this sexual distinction, following the discovery by Hatcher (1894) of ‘‘D.’’ pro- avitum with horns in the males in a very primitive state. The name of Diceratherium therefore ceases to have its original sense, all inclusive, and is now limited to one phase of the horned rhinoceroses, the type of which is D.. armatum Marsh. Other species of ‘‘diceratheres’’ may be, and some are, widely separated in their classification, as will be shown later. *For obvious reasons, space is not given to the publication of all refer. ences; the reader is therefore directed to the memoirs by Osborn (‘‘ The extinct rhinoceroses’’, Mem. Amer. Mus. Nat. Hist., vol. 1, 75-164, pls. 12A-20, 1898) and by Peterson (‘‘The American diceratheres’’, Mem. Car- negie Mus., vol. 7, 399-477, pls. 57-66, 1920), in which detailed descriptions, ae reproductions of all important types, and full bibliographies are pub- ished. 42 E. L. Troxell—Cenopus, the Ancestral Rhinoceros. Likewise the word Aceratherium, heretofore consid- ered to stand for a genus incorporating all aceratheres or hornless rhinoceroses, loses its etymological significance, and by exact definition, based in great measure on the teeth and parts of the skull other than the nasals, comes to be the name of a group which may be and probably is limited to the Old World. CLASSIFICATION OF SPECIES. Trigonias osborni Lucas 1900. Genoholotype. Cenopus mitis (Cope) 1874. Genoholotype. Cenopus pumilis (Cope) 1886. ‘Synonym of C. mitts. Cenopus (Leptaceratherium) trigonodus (Osborn and Wort- man) 1894. Subgenoholotype. Leads to C. platycephalus. Cenopus trigonodus allus, subsp. nov. Figs. 1, 2. Cenopus coper (Osborn) 1898. Leads to C. tridactylus. Cenopus occidentalis (Leidy) 1851. Inadequate. Cenopus tridactylus (Osborn) 1893. Cenopus dakotensis Peterson 1920. Synonym of C. tridactylus. Cenopus tridactylus proavitus (Hatcher) 1894 . Cenopus tridactylus metalophus, subsp. nov. Fig. 4. Cenopus tridactylus avus, subsp. nov. Fig. 5. Cenopus platycephalus (Osborn and Wortman) 1894. Cenopus platycephalus nanolophus, subsp. nov. Fig. 3. Cenopus simplicidens Cope 1891. Of doubtful validity. DIscussION OF GENERA AND SPECIES. Trigonas Lueas. The earliest species of the true rhinoceros is made the -genoholotype, Trigonias osborni Lucas. As summarized by Hatcher (1901), the upper teeth are unreduced, C, alone absent, simple superior premolars, P* large, P? with non-parallel lophs, four digits on the manus. Its geological age is that of the lower Titanotherium beds (lowest Oligocene). The ancestry of the genus is obscure, but it undoubtedly gave rise to Cenopus Cope. Cenopus Cope. Ceénopus 1s a genus which includes all of the White River (Middle and Upper Oligocene) species; it is based upon the holotype of C. mitis (Cope), a fragmentary lower jaw quite indeterminate specifically. The species is usu- ally represented by the paratype maxillary with molars and premolars (No. 6325, A. M. N. H.). E. L. Troxell—Cenopus, the Ancestral Rhinoceros. 48 In general, the genus is distinguished by the presence of two upper incisors, the absence of the canines (see Leptaceratherium below), the presence of rudimentary horn cores or none at all, parallel lophs on P?, and the tendency toward this arrangement in other premolars in later species. The generic group is composed of C. trigonodus (Osborn and Wortman), and C. copei (Osborn), two species which seem to lead respectively to C. platyceph- alus, the terminal member of its line, and to C. tridactylus, which probably furnished the source of all later forms, certain possible immigrants excepted. Cenopus (Leptaceratherium) trigonodus (Osborn and Wortman) as a type possesses the upper canine and thus forms the connecting link between this genus and 7'r7- gonias. This species has a further important primitive feature, a loop uniting the cross lophs of the premolars through the deuterocone and tetartocone, which are so blended as to appear as one element; in this respect also it approaches 7’. osborni, while on the other hand it trends toward C. platycephalus, its probable successor. A new subspecies of C. trigonodus is described on a later page in this paper. It illustrates an advanced step in the evolution: has already lost I® and C’, and has devel- oped a very prominent deuterocone on P* which envelops the thin sinuous metaloph (Cat. No. 12052, Y. P. M.). Cenopus platycephalus (Osborn and Wortman) is typ- ically an Upper Oligocene species, but smaller and more primitive specimens have been reported. Its type is marked by a broad low cranium and nearly obsolete sag- ittal crest; the species is also noted for the distinct sepa- ration of the tetartocone from the metaloph, the great reduction of the latter, the simplicity of the molars, and generally for the large size of the individuals. A new subspecies will be proposed (Cat. No. 12489, Y. P. M.) which, because of the extreme reduction of the metaloph and the expansion of the deuterocone to occupy the whole inner portion of the larger premolars, is thought to be the termination of its line, and to be in no way related to later genera. aes Cenopus cope (Osborn), although it is barely distin- guishable from C. occidentalis (Leidy) (heautotype, the holotype being lost), except in size, and although it resem- bles very much the paratype maxillary of C. mitis (Cope), 44. °K. L. ee the Ancestral Rhinoceros. yet should take precedence over either of these because their types are not adequate nor dependable. C. cope holds a very important place in taxonomy, since to a large extent it has usurped that of C. occidentalis, which is so frequently mentioned in our literature, and stands at the very beginning of that branch of the genus Cenopus which gives rise to C. tridactylus and probably many of the later genera of American rhinoceroses. Its geologi- eal level is the base of the Oreodon beds (early Oligocene). Cenopus tridactylus (Osborn) is a very important spe- cies having a variety of characters which are strongly emphasized in later forms. One is therefore convinced that this is a pivotal point in the racial evolution, and from it there arise two or more lines of descent. Throughout this species the following are notable features: (1) the development of the parallel lophs on the premolars, (2) the greater complication of the enamel of the molars by the presence of criste and erochets, (3) the loss of all trace of C’ and I’, (4) the reduction to the tridactylous manus, and (5d) the first appearance in the males of the thickened and rugose nasals for the support of horns. The development of horns here is in a very primitive state, but a considerable advance is made in the next stage, D. armatwm, where the horn supports are much more rugose and elevated, but still widely separated and situated well behind the tips of the nasals. Other subspecies are chosen to illustrate more fully the variety of forms in C. tridactylus and the trend of that species toward the true Diceratherium, especially with regard to the simple parallel cross lophs on the premolars. Specimen No. 10254, Y. P. M., is taken as the holotype of one new subspecies, and specimen No. 10251 of another; both are described on a later page. DESCRIPTION OF NEw SUBSPECIES. Cenopus trigonodus allus, subsp. nov. (Fies. 1 and 2.) Holotype, Cat. No. 12052, Y. P. M. Middle Oligocene (White River beds), Nebraska. The type material consists of the anterior portion of the face and the larger part of the lower jaws, not including the symphysis. The tooth series (fig. 2) is larger by the length of M® than that of the holotype of C. trigonodus or E. L. Troxell—Cenopus, the Ancestral Rhinoceros. 45 of C. copei. Other distinctive features consist of the small ridge in front of the protoloph and the great extension of the ectoloph forward on P', the reduced tetartocone of P? and its union through a broad ridge with the deuterocone, the strong deuterocone of P? and more especially of P*, and the weak metaloph which on P* is a thin band so narrow that a wide space is left in front and behind it for the deep fosse. A = va Fie. 1.—Cenopus trigonodus allus, subsp. nov. pS Side view of skull. x 1/3. The cingula are weak around the bases of the deutero- cones, but on the molars the cingula are discontinuous across the bases of the protocones and hypocones. Irreg- ular tubercles and ridges obstruct the entrance to the medifossette or central valley. There are no sharp sec- ondary folds on the molars, but the antecrochet is prominent. | Fic. 2.—Cenopus trigonodus allus, subsp. nov. ee Molar-pre- skull. - 1/3. I’ are present, but the third incisor and the upper canine are obsolete. The nasals are smooth, slightly expanded over P', and notched. There is a broad, shal- low depression in front of the orbit. The specimen is from layers later geologically than C. trigonodus but about the same age as C. Cope. 46 E. L. Troxell—-Cenopus, the Ancestral Rhinoceros. Cenopus platycephalus nanolophus, subsp. nov. (Fie. 3.) Holotype, Cat. No. 12489, Y. P. M. Middle or Upper Oligocene, Colorado. This new subspecies is founded on a holotype consist- ing of the permanent upper molars and premolars of a young individual. The newname has reference to the dwarfed condition of the metaloph. It represents an undescribed species of rhinoceros near C. platycephalus but because of its incompleteness is ranked as a sub- species. The tetartocone in each premolar except P* is closely joined to the deuterocone, and in P* these constitute a single element. P? varies from the others in having a groove on the outer side defining the two cones, which in this case are united to form a continuous loop of the inner lophs. On P' the metaloph is large and curves backward to enclose the postfossette; the protoloph is short and straight, while the ectoloph is broad and heavy and occupies the greater part of the tooth. Fie. 3—Cenopus platycephalus nanolophus, subsp. nov. Holotype. Molar-premolar series. x 1/3. In most species of Cenopus the anterior side of the larger premolars is greatly lengthened by having a prom- inent protocone antero-exteriorly, and a tritocone so sub- dued that this part of the ectoloph is smooth exteriorly, as in the molars. In the specimen under discussion, however, the equal prominence of the two outer cones gives this side of the tooth a squared form; the ectoloph is at right angles to the anterior and posterior sides of. the tooth. The premolars (except P!) are thus subquad- rate, with the inner sides rounded. The parastyle and metastyle are separated by grooves from the prominent exterior cones. The anterior cingulum is strong on each tooth except P! but it does not encircle the inner border completely. On E. L. Troxell—Cenopus, the Ancestral Rhinoceros. 47 P+ the postero-interior cingulum rises high on the tetar- tocone, and forms a veritable cusp or cone; it descends sharply on the inner side and becomes broken along the base of the deuterocone. On P? it becomes an integral part of the tetartocone, and on P?, antero-interiorly, the cingulum blends with the deuterocone, rising high on the _side to do so. The posterior cingulum of each molar is much less extended than is usual in the rhinoceroses of this time, so that not only is the hypocone a smooth rounded base, but the median valley also is uninterrupted by cusp or cingulum, in this respect differing from C. platycephalus. The postfossette 1s very small on M’? and on M? is entirely lacking. The antecrochet on the molars is low and broad, while an inconspicuous crista 1s present on each of the larger premolars. An unusual feature is seen on these premolars, in that the postfossette is larger than the medifossette and the two are confluent, due to the short metaloph; the median valley opens backward instead of inward and _ this, together with the dominance of the deuterocone, consti- tutes the chief feature of the subspecies. The type of the subspecies 1s about five sixths the size of that of C. platycephalus. Cenopus tridactylus metalophus, subsp. nov. (Fie. 4.) Holotype, Cat. No. 10254, Y. P. M. Probably Middle Oligocene, Rush- ville, Nebraska. The holotype of this new subspecies shows a strong tendency to have the cross lophs of all the premolars par- allel and unconnected. The form of these lophs would > ins VE ‘ Ze sy \ » =Y NSE = SS IN: IW S NZ ay IY Pie. 4.—Cenopus tridactylus metalophus, subsp. nov. Holotype. Molar- premolar series. < 1/3. seem to link it with C. tridactylus (Osborn) and remotely with Diceratherium Marsh. There is evident a close sim- 48 E. L. Troxell—Cenopus, the Ancestral Rhinoceros. ilarity to the skull of C. proavitus Hatcher in the form of the wide area between the parietal ridges on the sagittal crest. These ridges for a considerable distance are almost straight, converging at an angle of about 30° up to a point 8 or 9 em. from the occiput, whence they run unl formly parallel. The occiput rises well above the plane of the face. ; Both the proto- and metalophs are straight; the latter are especially thin and the terminating’ cones are not intimately connected with the strong postero-internal cingulum. The metaloph does not increase the length of its surface with wear, but with advanced age it may unite with the protoloph, at a point, however, scarcely more than halfway along the latter. The tetartocone, though small, is not recessive; it stands near the outer edge of the tooth crown, thus giving the great length to the metaloph. : The deuterocone, as it terminates the protoloph, swings forward, away from the tetartocone, in decided contrast to the C. trigonodus or C. platycephalus type of premolar, in which it curves backward, envelops the central part of the tooth and sometimes even the metaloph itself. The cingula.are interrupted.for short distances on the proto- cones and hypocones of the first and second molars, but the one is continuous on the protocone of the third molar. On P+ there is a small crista. The antecrochet is promi- nent on the molars, giving a strong curve forward to the median valley. There is a small groove running up the protocone. i The slender premaxillaries supported the first incisor teeth only, which were found separated from the skull. The nasals, extending out to the ends of the pre- maxillaries, are unusually. slender. This is commonly considered a sexual difference, but it is here presumed to be a feature of the earlier stages of the evolution, for no Middle Oligocene forms are known to have the rugose horn supports. . 3 This specimen is probably one of the progenitors of C. tridactylus which leads ultimately to the parallel-lophed rhinoceroses of the Great Plains, where in each succeeding | stage the enamel folding becomes more and more com- plicated. C. tridactylus is longer in the tooth series by the length of M*; C. copei is shorter by that amount. E. L. Troxell—Cenopus, the Ancestral Rhinoceros. 49 Cenopus tridactylus avus, subsp. nov. (Fie. 5.) Holotype, Cat. No. 10251, Y. P. M. Upper Oligocene (Protoceras beds), South Dakota. Cenopus tridactylus avus, subsp. nov., is very probably a true form of this species, but as a subspecies shows a decided trend toward Diceratherwum armatum (see fig. 6.) The type material consists of the skull of a young animal still retaining the last milk tooth, Dp*, and having the last molar uncut. The first three premolars (P+ is also uncut) are notable for the parallel, separate lophs, uniting only with wear. The metaloph is at first longer, but because of the extended base of the deuterocone, the protoloph soon surpasses it in length. PP?! has two paral- lel, backward curving crests, but the metaloph does not encircle a lake (postfossette) as does Osborn’s paratype (1898, pl. 13). On the larger premolars, small sharp Fic. 5.—Cenopus tridactylus avus, subsp. nov. Holotype. Premolars and first and second molars. 1/3. folds appear on the ectoloph, and on P? (left) one has an unusual position behind the metaloph. On P? and P® (right), there is a fold in the anterior angle between the two lophs. | _ Criste and crochets may be seen on the molars, and the latter, especially on M'!, have encroached so far on the. median valley as to isolate a small lake (medifossette). On the protoloph of M', two vertical valleys, anterior and posterior, partly separate the protocone from its proto- conule; the posterior valley emphasizes and sets off the moderate antecrochet. The inner cingula are broken across the bases of the protocone and hypocone, and are peculiarly offset where the two ends join in the median groove. = nh Am. Jour. Sci., FirrH Series, Vou. II, No. 7 —Juny, 1921. 4 ; 50 EH. L. Troxell—Cenopus, the Ancestral Rhinoceros. Not only in size but in the general form of the skull does this specimen resemble C. tridactylus; it has the ris- ing and double parietal. ridges extending into the sagittal crest. The nasal bones are long and slender, i A i TR su = Sern Tene \ \ me —_. = cau — “\a 7% {UN US ay \ iy Wesaamill\ < Z} iN iy) Fic. 6.—Diceratheriwm armatum Marsh. Holotype. Molar-premolar series. < 1/3. (See Peterson 1920 for reproduction of complete skull.) slightly wide over P!, where there appear actual shoulders or barbs resembling in this feature C. copet. Another specimen in the collection, Cat. No. 12059, Y. P. M., has the broad thick nasals, presumably of the male, but they do not show the rising protuberances so typical of the later Diceratherwm. Measurements of New Subspecies and also of D. armatum. C: C. OF C. D. allus nanolophus metalophus avus armatum No. 12052 No. 12489 No. 10254 No. 10251 No. 10003 Y.P.M. Y.P.M. “Yee MES Wee yee mm. mm. mm. mm. mm. Molar-premolar length ... 205 194 254 Premolar series, length... 98 7 Bs 98 1h 129 Molar series, length ...... 115 102 139 PES Width y DASel SY geist. ue ato 37 39 39 50 Ps, Jength,. centers... 2% - sn. 27 28 26 34 M*, width; ‘ant. i 2... ae 37 43 39 4k 53 | Me, lenethyicenteri2 2. 33 38 33 38 44 MES width; anit.t 2 ee een 39 48 40 45 56 MG, -lenioth, "center ie. cir 38 4] 35 39 50 M*, width, amibe (5 pseu eae 43 39 50 M*, length, inner side..... 39 35 48 SUMMARY. With further study of the great family of rhinoceroses it becomes evident that they can not be classified on the presence or absence of horns, a sexual variation; the female and young dicerathere had no horns; probably a male acerathere had them, at first in an incipient stage. The genus Cenopus Cope includes nearly a dozen dis- tinct species and subspecies, representing a long line of E. L. Troxell—Cenopus, the Ancestral Rhinoceros. 53 ungulate evolution extending throughout the Oligocene. Clearly separated from the Hyracodontide and Amyno- dontidz, this gave rise to all later forms, including the modern genera of rhinoceroses. Four new subspecies are proposed: Cenopus allus 1s noted for its strong protoloph and weak metaloph; C. nanolophus is so named from the dwarfed or incomplete metaloph on the premolars and the large posterior fossa. C. metalophus reverses the conditions of the others men- tioned and has a metaloph as long as the protoloph and the two are parallel. This is probably one of the progeni- tors of C. tridactylus. C. avus, although a valid sub- species of C. tridactylus, yet shows a very definite sim1- larity to Diceratherium Marsh and is ancestral to it. It is notable for the parallel cross lophs, complicated enamel bands, and its late Oligocene age. Se Le Nit hee WNT iG LG EN CE: I. CuHrmistry AND PuHysics. 1. A Recalculation of the Atomic Werghts—Dr. FRANK WIGGLESWORTH CLARKE, chemist of the U. S. Geological Survey, has now published the fourth edition, revised and enlarged, of this important work in the form of a volume of 418 quarto pages. The data of atomic weight determinations are presented very fully and the various ratios, with the exception of some that appear to be undoubtedly inaccurate, are calculated in con- nection with their mathematical probable errors. Then the available ratios are combined, with weightings according to their probable errors, in order to find the atomic weights. The author admits certain deficiencies in this mathematical method of calculation, due to the effect of constant errors in the deter- minations, such as the effect of impurities in the substances weighed, but it appears that his method is the best one available. A final table of atomic weights is presented in which the greater part of these constants are carried out to five figures. The table varies in this last respect from that of the International Com- mittee, and there are also other appreciable variations in the two tables. For instance, Clarke gives 27.039 for aluminium, while the International Tables give 27.1, and it is interesting to observe that Richards has found, just recently and too late for Clarke’s use in the work under consideration, that this atomic weight is probably about 26.96. 52 Scientific Intelligence. The work is a very useful one for the purpose of reference to what has been done in atomic weight determinations, and it will be a valuable aid to future workers in this field. Chem- ists should be grateful to the author for the prodigious amount of labor and the careful study that he has devoted to its prepa- ration —Memoirs Nat. Acad. of Sciences, Vol. 16, Third Memoir. H. L. W. 2. The Fundamental Processes of Dye Chemistry; by HAns Epwarb Fierz-Davip; Translated by FREDERICK A. MAson. 8vo, pp. 240. London, 1921 (J. and A. Churchill).—This is the English translation of an important Swiss work on the prac- tical side of dye chemistry. The book gives very full details for the laboratory preparation of many important intermediate products and dyes, and in connection with these descriptions there are interesting notes on the technique and practice of the factories. There are 49 excellent illustrations, including 19 plates, showing laboratory and factory apparatus. The book gives in a separate section a general discussion of various tech- nical details, including vacuum distillations, the construction and use of autoclaves, structural materials, works management, and the calculation of costs. A section is devoted also to analy- ' tical details. The book appears to be a very excellent one for the use of students of dve manufacture, both as a guide for laboratory work and a work of reference. It should be very interesting also to other students of organic chemistry as it well displays the high degree of perfection to which organic synthesis has been brought in this highly developed chemical industry. H. L. W. 3. Organic Chenustry for the Laboratory; by W. A. Noyes. 8vo, pp. 293. Easton, Pa. 1920 (The Chemical Publishing Company ).—This is the fourth edition, in which there are but few changes in comparison with the last issue of four years ago. As is well known, the book is an extensive laboratory manual for organic preparations including preliminary chapters on ulti- mate organic analysis and general operations, and a final chapter on the qualitative examination of carbon compounds. The pro- cesses are clearly described and there are abundant references to the literature in connection with them. The first edition of this book appeared in 1897, and it is evident from the frequency with which new editions have been issued that the book is extensively used. H. “Li. We 4. Qualitative Chemical Analysis; by M. Cannon SNEED. 8vo, pp. 198. New York, 1921 (Ginn and Company).—This text-book has been prepared by the head of the division of gen- eral inorganic chemistry in the University of Minnesota. Its presentation of the subject differs very much from the usual - methods. os csahs a a1s° 700° Exposed in Ouachita region in Ok- ow - lahoma and Arkansas. NVomble ‘shale. ..0.... 2500-1,000° 1 Exposed in Ouachita region in Ar- : kansas; also present in Ouachita region in Oklahoma.4 Blakely sandstome .)......../: 00-500° Exposed in Ouachita region in Ar- kansas; present in Ouachita region in McCurtain Co., Okla.4 275. Taff, J A., and Adams, G. L., op. cit., p. 274. se Collier, A. J., The Arkansas coal field, U. S. Geol. Survey, Bull. 326, p. 12, 1907. 4 Taff, J. A., ~ Grahamite deposits of southeastern Oklahoma, U. S. Geol. Survey, Bull. 380, p. 289, 1909. i Measured by writer in Yell County, Arkansas. J Wallis, B. F., The geology and economic value of the Wapanucka limestone of Okla- homa, Oklahoma Geol. Survey, Bull. 23, pp. 30, 42, 67, 1915. * Wallis, B. F., op. cit., p. 67. 1Girty, G. H., The fauna of the Caney shale of Oklahoma, Wes. Geol Survey, Bull. 377, p. 6,:1909; Wallis, B. F., op. eit., p. 27. m Purdue, A. H., The slates of Arkansas, Arkansas Geol. Survey, p. 48, 1909. n Taff, J. A., U. S. Geol. Survey, Geol. Atlas, Atoka folio (No. 79), colum- nar section sheet 2; 1902. ©° Measured by A. H. Purdue and writer in Ar- kansas. P Ulrich, EH. O., Revision of the Paleozoic systems, Geol. Soc. Amer. Bull., vol. 22, p. 677, 1911. aC. W. Honess, structural features of the south- ern Ouachita Mountains, Oklahoma (abstract): Geol. Soc. America, Bull, volvol, No. 1, p: 121, March, 1920. 66 H. D. Miser—Llanoria, the Paleozoic Land Mazarnr shales... 4.1. -\-eeeees 1,000° Exposed in Ouachita region in Ar- L BG kansas; also present in this re- : . gion in Oklahoma.4 Ordovician (?): Crystal Mountain sandstone...850°, Exposed in Ouachita region in Ar- Cambrian: kansas; also present in this re- Collier shale (observed thick- gion in McCurtain Co., Okla.4 ness) ob -aee. de. duseihs.- nee 2000 The Caney shale and the underlying formations—the Jackfork sandstone, Stanley shale and Hot Springs sand- stone of the Ouachita Mountains—have been placed in the Pennsylvanian series by some geologists but other geologists and the accepted usage of the U. 8. Geological Survey place them in the Mississippian series. As the proper correlation of these formations has an important bearing on several features to be discussed below, brief summaries of E. O. Ulrich’s opinion and of the evidence supplied by their fossils are presented. The Stanley and the Jackfork have yielded a few plants and the Jackfork has yielded a few indeterminable invertebrate fossils, but the Caney shale has yielded a rather large invertebrate fauna and a few fish remains. No fossils have been found in the Hot Springs sandstone. -In summarizing the evidence furnished by the plant collections obtained prior to 1915 by the writer and others from the Stanley shale and Jackfork sandstone David White’ says: ‘“The discovery of better material will doubtless necessitate re- vision of some of the tentative [specific] identifications. Possi- bly they will show that the beds are Pennsylvanian, but the aspect of the plant fragments and the apparent relations of the beds strongly suggest that they are Mississippian. Accordingly, I am inclined to regard them as Mississippian, and to suggest that they are of Chester age, but the paleobotanical data available is insufficient to justify their conclusive reference to the Mississip- pian.’’ C. S. Prosser, who collected some fragments of fossil plants from the Stanley shale in the city of Hot Springs, Ark., made the following statement concerning them:’ ‘On one of the olive pieces of shale is a fern pinnule, which is similar to those of Sphenopteris. It resembles ° Statement for use in the Hot Springs and DeQueen-Caddo Gap folios (in preparation ). * Prosser, C. S., Notes on Lower Carboniferous plants from the Ouachita uplift, Arkansas Geol. Survey Ann. Rept. for 1890, vol. 3, pp. 423-424, 1892. Area wm Louisiana and Eastern Texas. 67 somewhat the pinnules of Sphenopteris decomposita Kidston, from the Calciferous sandstone (Lower Carboni- ferous) of Scotland; but nothing could be stated posi- tively of such a fragment. Other fragments resemble Cordaites.’’ C. R. Eastman,!® who studied fish remains from the Caney shale, stated that their character tends to support the upper Mississippian age of the Caney. A part of a recent summary by George H. Girty' on the invertebrate fauna of the Caney shale follows: ‘When the formation [Caney] was first mapped and when its fauna was first described the Caney shale was referred, as it is now, to the upper part of the Mississippian series. * * * ‘Since this conclusion was formed much evidence has accumu- lated, and it tends strongly to corroborate the opinion that the Caney shale is of Mississippian age. Hundreds of collections of invertebrate fossils have been made in Oklahoma and Arkansas in areas adjacent to those in which the Caney shale occurs. In these collections a pronounced. faunal change is shown between the Morrow group, which is of Pottsville age, and the formations that underlie it, whose faunas, though differing more or less pro- foundly from the typical Mississippian faunas farther north, are nevertheless undoubtedly Mississippian. Wherever faunas of the Mississippian type occur they occur below faunas of the Morrow type, and the strata that contain them can be traced to other sec- tions in which the same relation of rocks and faunas is main- tained. The same relations are shown by the Caney shale and the formation that lies next above it, the Wapanucka limestone. The Caney fauna has conspicuously the facies of the Mississippian faunas of the adjacent areas in Oklahoma and Arkansas. This fact admits of no doubt. Furthermore, the fauna of the Wapa- nucka limestone is closely allied to that of the Morrow, which overlies the Mississippian rocks in nearby areas and without much doubt represents the same geologic epoch. . ‘*Tt is true that as the Morrow is believed to be of upper Potts- ville age other rocks may occur below it and still be Pottsville, but in that case their faunas might justly be expected to have the Pottsville rather than the Mississippian facies. It may be well to recall that the Caney fauna, so far as it is known, comes from the lower half of the formation, but so long as collections continue to show the facies of the Mississippian faunas that occur below the Morrow the Caney shale can logically be placed only in the Mis- Sissippian.”’ * Hastman, C. R., Brain structures of fossil fishes from the Caney shales; Geol. Soc. America, Bull., vol. 24, pp. 119-120, 1913. ™ Statement for use in the Hot Springs folio (in preparation). 68 H. D. Miser—Llanoria, the Paleozoic Land E. O. Ulrich,!? who has made field studies of the forma- _ tions under discussion, holds: (1) that the Hot Springs sandstone and Stanley shale are equivalent to the Chester group and to beds that bridge the Chester-Pottsville interval, (2) that the Jackfork sandstone is of lower Pottsville age, and (3) that the Caney shale is of upper Pottsville age. The reasons for these opinions can not be discussed here for lack of space. EVIDENCE FOR A PALEOZOIC LAND AREA‘IN LOUISIANA AND EASTERN TEXAS, AND ITS FEATURES. Any land area that may have existed in Louisiana and eastern Texas during the Paleozoic era is now largely if not entirely concealed by Cretaceous and younger sedi- ments of the Gulf Coastal Plain. Evidence regarding it must therefore be obtained from (1) the Paleozoic and older rocks that are exposed in the regions bordering the Gulf Plain, (2) the structure of the sediments of the Gulf Plain, and (3) wells that have passed through the Creta- ceous and younger rocks of the Gulf Plain and penetrated the underlying Paleozoic and pre-Cambrian rocks. This evidence follows. General character of Ordovician and Silurian rocks in Ouachita Mountains. The rocks of Ordovician and Silurian age exposed in the Ouachita Mountains consist mainly of shale and sandstone, whereas the rocks of these ages in the Arbuckle Mountains, in the Ozark region, and in the Nashville dome in middle Tennessee consist predominantly of limestones. This strongly suggests that the present Ouachita region was near an old land area undergoing vigorous erosion during these two periods, and if this is true it is necessary to assume that the old land area existed south of the present Ouachita Mountains. Blakely sandstone of Ouachita Mountains. The Blakely sandstone, of Ordovician age, thins out to the north in Montgomery County, Ark. This forma- tion is 500 feet or less thick and is composed largely of shale but partly of sandstone, though the sandstone is 2 Oral communication. Area in Lowmsiana and Eastern Texas. 69 the more prominent surface feature of the two. The sandstone beds are lenticular and thin out to the north, whereas the intervening beds of shale do not appear to thin out in this direction. The absence of the sandstone to the north therefore can not be explained by the hypo- thesis that it extended farther north and that it was subse- quently eroded. Blaylock sandstone of Ouachita Mountains. Although the Blaylock sandstone, which at places reaches a thickness of 1,500 feet and is of Silurian age, is of wide extent from east to west, its outcrops stretch- ing from a point near Malvern, Ark., nearly to Bismarck, Okla., it is present in the Ouachita Mountains only on their south side. The northward thinning of the sand- stone may be due partly to erosion, as is indicated by the local occurrence of a conglomerate at the base of the over- lapping Missouri Mountain slate. If the thinning out of the sandstone is due entirely to erosion this would mean that at least 1,500 feet of material has been removed from the northern part of the present Ouachita region, and it would be expected that the underlying Polk Creek shale would also have been removed from large areas at the same time the Blaylock was being removed. But the Polk Creek shale is generally present in the region north of that in which the Blaylock sandstone occurs, and its thickness there is much the same as it is in places where it underlies the Blaylock. The conclusions regarding the Blaylock are that it was deposited in a minor east- west trough on the south side of the Ouachita geosyn- cline, that the northward thinning of the formation can be attributed in only a very small part to erosion, and that the land-derived sediments for it came from the south. Stanley shale and Jackfork sandstone of Ouachita Mountains. The Stanley shale, 5,000 to 6,000 feet thick, and the Jackfork sandstone, 5,000 to 6,600 feet thick, both of Mississippian age, are exposed through the entire length of the Ouachita region, and the Jackfork sandstone is exposed at places in the Arkansas Valley in Arkansas but both formations thin out to the north and west. They are absent in the Arbuckle Mountains, and at a locality on 70 H. D. Miser—Llanoria, the Paleozoic Land the north border of the Ouachita region near McAlester, Okla.,'* and also in the Ozark region, though in that region. they may be represented by comparatively thin lime-. stones, sandstones, and shales of Mississippian age. It may be suggested that these two formations for- merly extended much farther west and north and that their absence is due to erosion, but there is no evidence to indicate that any considerable thickness of strata was removed by erosion from the Arbuckle and Ozark regions during the Mississippian epoch. Not only do the formations themselves become thinner toward the north, but sandstone beds that form about one-fourth of the Stanley..shale along the southern border of the Ouachita region become thinner or thin out completely before they reach the north side of the region; and the Jackfork sandstone changes toward the north from a formation composed almost entirely of sandstone with very little shale to a for- mation composed largely of shale. This northward thinning of the sandstone beds of the Stanley shale and the dovetailing of thick beds of shale in the Jackfork sandstone to the north imply a southern source for the sand and mud that later formed these formations. Many small quartz pebbles, one-fourth of an inch or less in diameter, occur in the Jackfork sand- stone, particularly in its lower part, on the southern border of the Ouachita Mountains. They become less abundant toward the north. The enormous thickness and comparatively large areal extent of the Stanley and Jackfork indicate that the land mass to the south suffered great erosion. From the evidence now at hand the Arbuckle and Ozark regions could not have supplied so vast a quantity of sediment during the Mississippian epoch. , The northward thinning of the sandstones in the forma- tion to which the name Stanley shale is applied was noted by L. 8. Griswold,1+ who says, ‘‘The existence of sand- stone beds overlying the novaculites on the south side of 3 Girty, G. H., The fauna of the Caney shale of Oklahoma, U. S. Geol. Survey, Bull. 377, p. 6, 1909. Wallis, B. F., The geology and economic value of the Wapanucka limestone of Oklahoma, Oklahoma Geol. Survey, Bull. 23, p. 27, 1915. 14 Griswold, L. S.,. Whetstones and the novaculites of Arkansas, Arkansas Geol. Survey, Ann. Rept. for 1890, vol. 3, pp. 193, 213, 1892. Area wm Louisiana and Eastern Texas. 71 the Ouachita uplift, with shale beds oceupying the corre- sponding position on the north side, indicates that the land whence these sediments: were derived lay to the south, just as in the case of the Appalachians it lay to the east.”? G. H. Ashley,!® who studied a large area of Carboniferous rocks underlain by the Stanley, Jackfork, and Atoka formations south of the area examined by Griswold, says that they apparently confirm Griswold’s conclusion regarding the southern source of the Carboni- ferous sediments. Concerning the source of the clastic sediments of not only the Stanley and Jackfork but of the Caney and Atoka formations, David White!® says: ““Toward the northeast [of north-central Texas], somewhere in the region of the Red River Valley, a Mississippian-Pennsylva- nian land barrier existed which is now bridged by later Pennsyl- vanian ‘‘Red Beds’’ or Cretaceous strata. The existence of such a land mass is predicated. by the sediments (clastics) of the Jack- fork, Stanley, Caney, and Atoka formations as well as by the fos- sils. The sediments of these formations could hardly have been derived from the Ozark uplift, nor does it seem probable that they could have originated in the areas now marked by the Ar- buckle-Wichita uplift. ’’ Tuffs of Mississippian age in the Ouachita Mountains. -Tuffs occur near the base of the Stanley shale in Polk County, Ark., and McCurtain County, Okal., in three and possibly four or five beds, which range in thickness from 6 to 85 feet, the lowest bed being the thickest and the most widely distributed. According to E. 8. Larsen, who has studied them in thin sections, these tuffs are composed in large part of devitrified and silicified volcanic glass and of feldspar and other minerals. in a brief discussion of the Paleozoic rocks of the Ouachita Mountains, expresses the opinion that the land area that furnished the material for these immensely thick series of rocks lay to the south and southeast. He continues, ‘‘The relative position of the continental and oceanic areas was therefore at this time [Paleozoic era] somewhat reversed—the ocean occupying the greater part of what is now the central and western United States and the land the Coastal Plain of the east- ern and southern United States and portions of the Atlantic Ocean and Gulf of Mexico.’’ Pennsylvanian rocks of north-central Tezas. According to N. F. Drake*® most of the clastic material that forms the Pennsylvanian rocks of the Colorado coal field in north-central Texas appears to have been derived from an extensive old land area to the east and northeast, “ Ulrich, E. O., Revision of the Paleozoic systems, Geol. Soc. America, Bull., vol. 22, p. 352 footnote, 1911. “ Woodworth, J.. B., Bowlder beds of the Caney shale at Talihina, Okla- homa, Geol. Soc. America, Bull., vol. 23, pp. 457-462, 1912. Abstract, Science, new ser., vol. 35, p. 319, 1912. * Taff, J. A., op. cit., Science, new ser., vol. 21, p. 225. ” Veatch, A. C., Geology and underground water resources of northern ear and southern Arkansas, U. 8. Geol. Survey Prof. Paper 46, p. 17, * Drake, N. F., Report on the Colorado coal field of Texas, Texas Geol. Survey, Fourth Ann. Rept., pp. 373-374, 1893. (Reprint), University of Texas, Bull. No. 1755, pp. 15-16, 1917. Area wn Lowmsiana and Eastern Texas. 75 now covered by later formations, and only a very small part of it from the older rocks of the Central Mineral region. His reasons for this conclusion may be briefly summarized as follows: 1. The outcrop or strike of the beds is almost at right angles to the northern border of the Central Mineral region. 2. The beds indicate deeper water and slower deposi- tion near the Central Mineral region than farther north. 3. Hach bed at or near the border of the Central Min- eral region dips westward and overlaps in this direction the underlying beds, in much the same way that the younger foreset beds of delta deposits overlap the older beds. 4. Conglomerates extend almost to Red River, and the pebbles composing them remain remarkably uniform in character; they include no pebbles of limestone and marble such as would be derived from the rocks in the Central Mineral region. d. The beds indicate that the sea was deeper to the west than to the east. The same view regarding the source of the land-derived sediments of the Pennsylvanian rocks of north-central Texas has been expressed by C. L. Baker,?” R. T. Hill,?* K. T. Dumble,”® and F’. B. Plummer,®° but Hill at the same time expressed the view that an old land mass in eastern Texas also supplied the sediments for the Carboniferous rocks in southeastern Oklahoma and western Arkansas. . Carbon ratios of Pennsylvanian coals wn northern Texas. M. L. Fuller in a recent paper on the relation of oil to 77 Udden, J. A., Baker, C. L., Bose, Emil, Review of the geology of Texas, Texas Univ., Bull. No. 44, pp. 196-107, 1916. *° Hill, R. T., Geography and geology of the Black and Grand prairies, Texas: U.S. Geol. Survey, Twenty-first Ann. Rept., pt. 7, pp. 91-92, 103-104, 1901. 2» Dumble, E. T., The individuality of Texas geology, The Rice Institute pamphlet, vol. 3, No. 2, pp. 155-156, April, 1916. Origin of the Texas domes, Am. Inst. Min. Eng., Bull. 142, p. 1634, Oct., 1918. The Geology of East Texas, Univ. of Texas Bull. No. 1869, pp. 11-13, 1920. Discussion of paper by E. DeGolyer on the theory of the volcanic origin of salt domes, Am. Inst. Min. and Met. Eng., Trans., vol. 61, p. 476, 1920. * Plummer, F. B., Preliminary paper on the stratigraphy of the Pennsyl- vanian formations of north-central Texas (unpublished manuscript). 76 H. D. Miser—Llanoria, the Paleozoic Land carbon ratios of Pennsylvanian coals in northern Texas?! says: ; ‘‘The high carbon ratio east of the Carboniferous area, appar- ently higher than that around the Wichita Mountains on the north or the Central Texas Uplift on the south, is very suggestive and apparently points to an area of high disturbance beneath the Cretaceous immediately east of the margin of the latter. Whether there is an old land mass of pre-Pennsylvanian rocks, an arch of older Pennsylvanian (Bend, ete.) or a series of troughs of the latter between arches of older rocks, is not yet estab- lished.’’ Similar conclusions have also been expressed by Fuller in the references cited below.*” Thickness and extent of sediments derwed from Llanoria. Llanoria was greatly croded and was of vast size, as shown by the large areal extent and enormous aggregate thickness of the Paleozoic rocks in the Arkansas Valley and Ouachita Mountains and of the Pennsylvanian rocks of north-central Texas. : | The maximum thicknesses of the rock formations in the Ouachita Mountains and Arkansas Valley as given on page 64 aggregate 37,000 feet, but as their thicknesses differ considerably from place to place the total thickness in any particular part of these regions would be less than the aggregate given. Nevertheless the following esti- mates by several geologists of the aggregate thicknesses in different parts of the regions indicate that between 20,000 and 25,000 feet of rocks, of which fully 90 per cent are clastic, were laid down in the greater part of the Ouachita geosyncline comprising the present Ouachita Mountains and Arkansas Valley. | The -total of the minimum and maximum thicknesses of the rocks in the Atoka and Coalgate quadrangles of Oklahoma, as given by J. A. Taff,?? are 21,400 and 22,400 * Fuller, M. L., Relation of oil to carbon ratios of Pennsylvanian coals in north Texas, Econ. Geol., vol. 14, no. 7, p. 541, Nov. 1919. * Fuller, M. L., Carbon ratios in Carboniferous coals of Oklahoma, and their relation to petroleum, Econ. Geol., vol. 15, No. 3, p. 234, April-May, 1920, Discussion of paper by F. B. Plummer on the stratigraphy of the Pennsylvanian formations of North-Central Texas, Assoe. Amer. Petroleum Geologists, Bull., vol. 3, pp. 149-150, 1919. “ Taff, J. A., U. S. Geol. Survey Geol. Atlas, Coalgate folio (No. 74), 1901, and Atoka folio (No. 79), 1902. Area wm Louisiana and Eastern Texas. (us feet, respectively. J.C. Branner*‘ has estimated that the Carboniferous rocks in the Arkansas Valley in Arkansas are 23,780 feet thick; N. F. Drake*®> has estimated that the ‘‘Coal Measures deposits’? in Oklahoma are 24,500 feet thick; and the thickness of the rock formations of Cambrian to Carboniferous age in the Ouachita Moun- tains in west-central Arkansas, as given by A. H. Pur- due,** aggregate 24,000 feet. The combined width of the two regions here mentioned is 80 to 100 miles, and their length is about 200 miles. As the rocks were compressed into east-west folds and considerably faulted about the close of the Pennsylvanian epoch, they now occupy a smaller area than they did when they were horizontal or nearly so. The compression, as calculated for a large part of the Ouachita Mountains in Arkansas, has reduced this horizontal extent almost one-half. Furthermore, the rock formations of the Ar- kansas Valley and Ouachita Mountains extend an unknown though probably considerable distance both eastward and southward beneath the Gulf Coastal Plain. The Pennsylvanian rocks of north-central Texas extend from the Central Mineral region northward to the State line and aggregate more than 5,000 feet in thickness, but only part of the Pennsylvanian sediments were laid down over all the area in which these rocks are now exposed, as is shown by the thinning of the strata to the west and their overlapping in this direction*upon the Bend series of the Texas Geological Survey.*7 Age and thickness of the exposed rocks of the Gulf Coastal Plain. The exposed rocks of the Coastal Plain are of Lower Cretaceous, Upper Cretaceous, Eocene, Oligocene, Mio- cene, Pliocene and Quaternary ages. H. W. Shaw** has ** Branner, J. C., Thickness of Paleozoic sediments in Arkansas, this Journal, (4), vol. 2, pp. 229-236, 1896. * Drake, N. F., A geological reconnaissance of the coal fields of the Indian Territory, Am. Phil. Soc. Proc., vol. 36, p. 388, 1898. ** Purdee, A. H., The slates of Arkansas, Arkansas Geol. peo pp. 30, 48, 1909. ar Drake, N. F., Report on the Colorado coal field of Texas, Texas Geol. Survey, Fourth Ann. Rept., pp. 374 et seq., 1893; (Reprint), University of Texas Bull. No. 1755, pp. 16 et seq., 1917. * Shaw, E. W., Stratigraphy of the Gulf Coastal Plain as related to salt domes, Washington Acad. Sci., Jour., vol. 9, No. 10, p. 289, May 19, 1919. Am. Jour. Sct.—F1rTH Serizs, Vou. II, No. 8.—Aveust, 1921. 6 78 H. D. Miser—Llanoria, the Paleozoic Land summarized as follows the thicknesses of the sediments of these ages in Louisiana and eastern T'exas: ‘< 2/5. 106 M. R. Thorpe—John Day Eporeodons Measurements of Holotype. mm. Total length ‘of skull?) 2022 A SOS Ae 208 Bizygomatie Gianieter’. . 2900. eS. . PAPAL 38 121.6 Superior molar‘ series; length 3. fi. co cs eens 42.3 Superior premolar series, length................... 40 Diameter, postorbital ‘constmctiom: 2:0.222245-84¢ 36.5 Eporeodon perbullatus, sp. nov. (Fies. 9, 10.) Holotype, Cat. No. 11011, Y. P. M. Upper Oligocene (upper John Day), Bridge Creek, John Day River, Oregon. Collected by S. H. Snook in 1874. Paratypes, Cat. Nos. 12319 and 12320, Y. P. M., Upper Oligocene (middle John Day), also from Bridge Creek. Collected by L. 8. Davis in 1874. Specific characters.——Bulle relatively enormous, full and ovate and nearly twice the size of those in E. lepta- canthus, which is the largest species of this genus in the John Day basin; lacrymal fosse deep and large; para- \ HUT / MT ALY ES | fe HA nam peel Ay 2 i nO ii \"f HIhY) jad RK x, AX Re YY SP ie =S \ - A\\ \\ \\: LF = WS S s 4 WS | 11071,TYPE Y. P.M. Fic. 9.—Eporeodon perbullatus, sp. nov. Holotype. Left lateral view. x 2/5. mastoids transversely compressed, ending inferiorly in a thin tip and they extend downward and well outward from the median line of the bulle; postglenoid tubercles relatively small; length of superior dental series inter- mediate between FE. pacificus and E. leptacanthus; nasal bones wide; cranium wider than in LH. leptacanthus; palate produced but a very short distance beyond last molar; masseteric fossa relatively deep. with Descriptions of New Genera and Species. 107 Nos. 11011 and 12320 are probably males, while No. 12319 is more delicately proportioned and may be a female. In the latter, the nasal bones are much more narrow, the orbits smaller, and the whole skull and jaws less robust, than in the other two. ‘SEN SAK Fig. 10.—Eporeodon perbullatus, sp. nov. Holotype. Left half, superior view. >< 2/5. - Measurements of Holotype. mm. PMotemmuemmentin, Oe SKULL 6 oo ors aba ole cue «we 4 toe oe ernie. de Papal Era Ommatie CUAMeTEr fo. occ. cot oe eee pe ee een 138 Superior molar-premolar series, length.............. 95 Superiog premolar series, length,.................. 47 Dianierexpostorbital constriction.................- a A, fee panel TiMea Ke LTO Inl tals Rete os Sic ess wae see oe 186 itimercion molar series. lemeth. 3.8... be de Sale os 52 Inferior dental series, with P,, length .............. 102 Pullen OSL wOIAMELER 6 es we ee ee ee 31.3 ieameverse diameter... 6.62. oe. Be ee kee es 25 PaStemicalu@ta nme el 6). 0 os. 5. seedy s beleent oe wele os ees Pall Oreodontoides oregonensis, subgen. et sp. nov. (Fics. 11-13.) Holotype, Cat. No. 12329, Y. P. M. Upper Oligocene (upper John Day), Turtle Cove, John Day River, Oregon. Collected by William Day in 1875. Distinctive characters.—Size small, length less than that of EL. tragonocephalus; muzzle pointed; face narrow; orbits nearly round, looking chiefly outward, but some- what upward and forward; cranium very full; no sag- ittal crest, as frontal ridges do not unite; postorbital constriction very wide; skull depressed at each extrem- ity; lacrymal fosse well. marked, but small; meso- cephalic. The sides of the meso- and metastyle of M? are straight, giving the metacone a square outline, instead of 108 M. R. Thorpe—John Day Eporeodons rounding at the base as in other species. This may or may not be a specific character. DQ Way Mf Wy Z| pee LL aS = = ——— . \ YPM: eR Ge CSF Fig. 11.—Oreodontoides oregonensis, subgen. et sp. nov. Holotype. Right lateral view. x 2/3. Great size of brain chamber, lack of any sagittal crest, unusual diameter of postorbital constriction, and a marked tendency toward brachycephaly are the most marked characteristics of this form. hs iy; a oe TYPE Freee Wf SN PVE Vx " Ll LF he Y : WGE {GGG SSS SEO SS Tj SEN NG ce one AN Uke ee ~ ARN AY CR :: E] SSN ‘7 AP 12329, TYPE ne a at Y.. ley M. \J “ANNA, SQ Fie. 12.—Oreodontoides oregonensis, subgen. et sp. nov. Holotype. Right half, palatal view. x 2/3. Fig. 13.—Oreodontoides oregonensis, subgen. et sp. nov. Holotype. Right half, superior view. x 2/3. with Descriptions of New Genera and Species. 109 Measurements of Holotype. Hopaimensrhor skal, Bore Od Yin GTO tous p 160* Duperior molar series, lenoth’!))2) 0 aul lelee) : 31.7 pulpemor premolar sertes lensth......:..........,, 30 eb icra TNA WWTGULIN 9. AS ty. ava us choc ww favere cig ¢ ees Spay Diameter. postorbital/comstriction.................- 42 * Approximate. Paroreodon marsh, gen. et sp. nov. (Fies. 14-16.) Holotype, Cat. No. 12415, Y. P. M. Upper Oligocene (middle John Day), Haystack Valley-Turtle Cove area, John Day River, Oregon. Collected -by L. 8. Davis in 1875. Distinctive characters.—Size small; brachycephalic; facial vacuities in advance of orbits, bounded by lacrymal, frontal, and maxillary bones; enormous brain chamber; 12415, TYPE Zig y, Y YG Y SO INK vil ‘ owe \F ( Fig. 14.—Paroreodon marshi, gen. et sp. nov. Holotype. Right lateral view << 2/3. extremely short sagittal crest; face short and muzzle narrow; steep basicranial axis; bulla very large and robust, ending inferiorly in a sharp ridge; paroccipital process triangular, with greatest diameter transverse, abutting against bulla for two-thirds its length, and descending outward, forward, and downward; very small diastema between C and P'; palate produced posterior to M?; palatal vault uparched; three very small incisors crowded against each other and the canine; lacrymal fossa shallow and open, maximum diameter vertical; Am. Jour. Sci.—FirvuH SrErizs, Vou. II, No. 8.—AveustT, 1921, 8 110 M. R. Thorpe—John Day Eporeodons infraorbital foramen above posterior portion of P?, this foramen double, with a smaller one above and in advance of the larger. Both sides possess this double foramen, but it is possibly due to individual variation. } 12415 TYPE Y. P. M. ran & ‘ees SS Re | eee ‘ RIS Re VG? IN~~Y ; Ls Y pri» 9. he é f f S =A\\\\5 UR LQ y yy) , Sf a =, 2D, Yj YY fy. = os CR RRS RRR \ ADS \ . NS _ \\ XN . ’ ‘ AROS ae “ Ny ESSE NN v x Sos y Sap A Se ~ Won ed N CANS) YY \ YY SON \ oe S oy \ a Son) WAS ~ RAN RRR ‘ Na VN Ak = ln, “SS SSS 12415, TYPE Y. P.M. Fie. 16 ie 15.—Paroreodon marshi, gen. et sp. nov. Holotype. Right half, pa atal view. x 2/3. Fig. 16.—Paroreodon marsh, gen. et sp. nov. Holotype. Right half, superior view. > 2/3. Measurements of Holotype. mm Axial Jeneth,. basion to prosthiong.-.. s...2e) eee 141.2 Superior molar series, leneth’ i238 ..)....e ee eee 38 Superior premolar series, length ................... 39 Cranium ™iniaxcawadth ..2ee a ees Te. Cee 57.3 Diameter, postorbital consimethionmia.) 4... seen 43 Bulla, ant=post: diameter: 23 eke Mae, Le if. 2 ass Transverse diameter? . | 25a aioe, .@eate s: 21 Vertical: diameter .cvrpiets . a: Vite hee Lah eiehas 24 REFERENCES. Cope, E. D.—1880.—Observations on the faune of the marine Tertiaries of Oregon. Bull. U. 8. Geol. and Geog. Surv. Terr., vol. 5, 55-69. 1884.—A. Synopsis of the species of the Oreodontide. Proc. Amer. Philos. Soe., 21, 503-572. with Descriptions of New Genera and Species. 111 Cope, E. D.—1884.—B. On the structure of the feet in the extinct Artio- dactyla of North America. Pal. Bull. 39. — 1884.—C. The history of the Oreodontide. Amer. Nat., 18, 280- 282. — 1888-1889.—The Artiodactyla. Ibid., 22, 1079-1095; 23, 111-136. Leidy, J.—1856.—Notice of some remains of extinct vertebrated animals. Proe. Acad. Nat. Sci., Phila., 8, 163-165, — 1873.—Contributions to the extinct vertebrate fauna of the western Territories. Rept. U. S. Geol. Surv. Terr., 1, 14-358. Loomis, F. B.—1920.—On Ticholeptus rusticus and the genera of Oreodon- tide. This Journal (4), 50, 281-292. Marsh, O. C.—1873.—Notice of new Tertiary mammals. Ibid. (3), 5, 407- 410. — 1875.—Notice of new Tertiary mammals. Ibid. (3), 9, 239-250. — 1884.—Dinocerata. U.S. Geol. Surv., Mon. 10. Matthew, W. D.—1899.—A provisional classification of the fresh-water Ter- tiary of the West. Bull. Amer. Mus. Nat. Hist., vol. 12, 19-75. — 1909.—Faunal lists of the Tertiary Mammalia of the West. In Bull. 361, U. S. Geol. Surv., 91-120. Merriam, J. C., and Sinclair, W. J.—1907.—Tertiary faunas of the John Day region. Bull. Univ. California, vol. 5, 171-205. Scott, W. B.—1890.—Beitrage zur Kenntniss der Oreodontide. Morpholog. Jahrb., 16, 319-395. Art. VIIL—Two New Forms of Agriocherus; by Mat- coLm RutrHeErRFoRD THORPE. [Contributions from the Othniel Charles Marsh Publication Fund, Pea- body Museum, Yale University, New Haven, Conn. | TABLE OF CONTENTS. Introduction. White River (Great Plains) species. A. antiquus antiquus Leidy. A. antiquus dakotensis, subsp. nov. A. migrans (Marsh). John Day Basin species. A. bullatus, sp. nov. Synoptic table of species. References. | INTRODUCTION. The genus Agriocherus has approximately as many synonyms as have the Chalicotheres. In 1850, Leidy described the first form as A. antiquus from the badlands of Nebraska. Other genera proposed since that time and now regarded as synonymous are: Hucrotaphus Leidy 1852, Coloreodon Cope 1879, Merycopater Cope 1879, Artionyx Osborn and Wortman 1893, and Agrio- meryx Marsh 1894. 112 M.R. Thorpe—New Forms of Agriocherus. Coloreodon and Agriomeryx were based on the presence of three instead of four superior premolars, while Arti- onyx was established on a pes and a portion of hind leg. Artionyx was the basis for a new suborder, Artionychia. Skeletal elements have been referred to no fewer than three mammalian orders, and the peculiarities of struc- ture exhibited by this genus have given rise to much speculation in regard to its taxonomy and life habits. The writer’s reasons for placing Eucrotaphus in the genus now under consideration will be more fully set forth in a subsequent paper, based chiefly upon Leidy’s descriptions and the work of contemporaneous and sub- sequent students. The former method of classification of the species on a basis of the possession of either three or four superior premolars has proved unreliable. However, the later forms usually have but three superior premolars. The osteology of this genus and its affinities have been very ably described and discussed in the papers cited in the list of references. The illustrations for the present paper were made by Mr. Rudolf Weber. WHITE RIVER SPECIES. Agriocherus antiquus antiquus Leidy 1880. Middle Oligocene (lower Brule), bad lands, Nebraska. Specific characters.—Skull approximately the size of Oreodon culbertsonu; orbits subrotund; infra-orbital foramen above interval between P? and P*; anterior part of palate strongly uparched; external buttresses of molars hemispherical; no internal cingulum on M*; postero-inter- nal lobe of P* very small; P® right triangular; P* molari- form but with anterior internal wall incomplete; muzzle long and narrow; bulle moderately large; superior pre- molars always four; inferior incisors three, but very small. Several specimens in the Marsh Collection have served for amplification of this type, especially Nos. 12657 and 120Gb. Yar os Measurements. mm. Breadth of forehead at postorbital processes (holotype)... 59.2 Superior molar series, length (No. 12657, Y. P. M.)...... Acie: M. R. Thorpe—New Forms of Agriocherus. 113 Inferior dental series with P,, length (No. 12666, Y. P. M.) 104 Inferior molar series, length (No. 12666, Y. P. M.) ee 53 Inferior premolar series, length (No. 12666, WA Ma 2 Depth of ramus below middle of M, (No. 12666, Y. P. M. si ». 445 Depth of ramus below middle of P, (No. 12666, Y. P.M.).. 32 Agriocherus. antiquus dakotensis, subsp. nov. qe. 1) Holotype (skull), Cat. No. 10106, Y. P. M.; paratype (jaws), Cat. No. 12665, ¥. P. M. Middle Oligocene ’ lower Brule), South Dakota. Specific characters.——Skull approximately the size of A. antiquus antiquus; palate more steeply uparched, espe- cially between the premolars; P* rotated forward and set obliquely in maxilla; P? almost an equilateral triangle in basal outline; infra-orbital foramen above interval between P? and P?; four superior premolars. The bulle extend forward to the glenoid surface and but slightly below it. They are in contact with the postelenoid co Oe cc fe Ll YUP, “re in LU ue ; Se » —— Cio lp 8 I \ ‘ \ IK Ay y ) 10106 , TYPE YAP. VE. Fie. 1—Agriocherus antiquus dakotensis, subsp. nov. Holotype. Right half, palatal view. Basal outline of bulla drawn from opposite side. x 1/2 tubercle and paramastoid process as well as the glenoid articular surface. Superior contour of skull nearly straight, the muzzle being of the same depth as the cra- nium; orbits small and round; an osseous ridge, depend- ing from the squamosal and parietal bones, and extending from the glenoid articular surfaces to the pterygoid pro- cesses, encloses a basicranial depression. This peculiar- ity I have not seen in any other species. The sagittal erest 1s moderately long. 114. M. R. Thorpe—New Forms of Agriocherus. Measurements of Holotype. mm Skull, length, occip. condyles to incisors, ine.............. 197* Bizygomatie diameter «. 2 icy. sere ee See eee 103* Brain-case, max. Width... 440% acetal One ae eee 61 Superior dental series, with C, length................... 106 Superior molar series, length. 2.2.2) ames 2 6 ye ee 43 Inferior molar series, length (No. 12665, Y. P. M.)...... 47.2 Inferior premolar series, length (No. 12665, Y. P. M.).... 38.7 * Approximate. Agriocherus migrans (Marsh) 1894. Holotype, Cat. No. 10102, Y. P. M. Upper Oligocene (Protoceras beds), South Dakota. Specific characters.—Skull somewhat longer than < 3/5. low and relatively short; shallow concavity between tem- poral ridges anterior to their junction; temporal ridges short, beginning well posterior to orbits; palate steeply inclined to sagittal suture, with a cross-section like an inverted V; palatonarial border opposite posterior lobe of 116 WM. R. Thorpe—New Forms of Agriocherus. M2? (in adult this would probably be farther back) ; basicranial axis shallow; paroccipitals plate-lke and standing at an angle of about 45° to the sagittal plane; postglenoid robust; basisphenoid nearly flat between bulle: infero-anterior termination of occipital condyles extends forward below basisphenoid in the shape of a shelf; bulla has a flat, nearly vertical surface facing inward and backward, joining the paroccipital process; antero-externally a ridge runs forward and inward ( ; XS : \ LOS WO WW YON V2 SNR 12424 ,- AYRE ——s te ’ IN N ee y Ve ESS YG I AS NSS> Ht} SS Ann x Y§lISNS iS 5 \\) AUN wey x SSS g N QM *\\\ \\\\\ A TRUITT A \ Mie WONG ? Fic. 4.—Agriocherus bullatus, sp. nov. Holotype. Left half, palatal view. < 3/5. beyond the middle of the glenoid articular surface; infer- ior surface of bulla keeled, the keel running transversely from the postglenoid tubercle, with which it is in contact, to the lower border of the internal plane face; long axis of bulla lies at about a 35-degree angle from the sagittal plane, the anterior portion approaching the pterygoid process, a form of bulla which does not occur in any other species of this genus. Measurements. mm. Skull, total length, occip. condyles to C, ine.............. 1%54 Bizygomatie aiamieter.... 2... Soe SOE cle cae 102 Diameter .of postorbital, constrichionge. 26 22 42525 3 39 Dentition, P? toe, anc: Nemsphes 2 ee ee ee OT M? +- M*, leneth oS orreeeeer rs. oo. eee ee 29 Brain-case, max. diameter. sees 1 ee ee 58 * Approximate. SYNOPSIS OF SPECIES. 1. Infraorbital foramen above interval between P2 and P®. Size about that of Oreodon culbertsonii; bulle small; pal- ate very steeply uparched; palatonarial border oppo- M. R. Thorpe—New Forms of Agriocherus. 117 site anterior lobe of M?; nasals pointed posteriorly ; four superior premolars. Middle Oligocene (lower BS NOs Se ot A. antiquus dakotensis, subsp. nov. About same size as above; bulle large; palate gently con- cave; palatonarial border opposite anterior part of M°; nasals acute posteriorly; four superior premolars. Upper Oligocene (middle and upper Jehn Day). A. trifrons Cope. Skull size of second above; bull small; palate gently concave; palatonarial border opposite posterior lobe of M’; nasals blunt posteriorly; three superior premolars. Upper Oligocene (middle and upper John Day). A. ferox (Cope). 2. Infraorbital foramen above anterior lobe of P?. Skull about size of Eporeodon major; bulle large and medially constricted; palate strongly concave; palato- narial border acute and opposite middle of M*; nasals broadly rounded posteriorly; four superior premolars. Upper Oligocene (middle John Day). A. ryderanus Cope. 3. Infraorbital foramen above middle of P*. Somewhat larger than O. culbertsonii; bulle large; pal- ate flat; mternal wall of P* complete; either three or four superior premolars. Middle Oligocene (lower ESTELLE) Sen ae ea et A. latifrons Leidy. Skull about size of that of Hporeodon major; bulle unknown ; palate nearly flat; palatonarial border oppo- site posterior part of M*,; nasals rounded posteriorly ; three superior premolars. Upper Oligocene (middle and upper John Day). ...... A. macrocephalus (Cope). Size about that of O. culbertsonu; bulle moderately large and inferiorly keeled in transverse plane; palate steeply inclined; palatonarial border opposite anterior part of M*; nasals obtuse posteriorly; three superior premo- lars. Upper Oligocene (upper John Day). A. bullatus, sp. nov. 4. Infraorbital foramen above posterior part of P*. - Skull about size of second above; bulle unknown; palate gently coneave; palatonarial border opposite middle of M?; nasals rounded posteriorly; three superior premo- lars. Upper Oligocene (Protoceras beds). A. migrans (Marsh). 5. Infraorbital foramen above interval between P* and P*. Size slightly greater than O. culbertsonn; bulle moder- ately inflated; palate strongly uparched anteriorly ; internal’ wall of P, incomplete; four superior premo- lars; palatonarial border opposite anterior lobe of M’; 118 M. R. Thorpe—New Forms of Agriocherus. nasals pointed posteriorly. Middle Oligocene (lower Bralkejiih .¢ Gabi oe as rahe A. antiquus antiquus Leidy. Size about equal to that of Hporeodon major; bulle small; palate nearly flat; palatonarial border opposite poste- rior edge of M?; nasals pointed posteriorly ; four supe- rior premolars. Upper Oligocene (middle John Day). A. guyotianus Cope. 6. Infraorbital foramen unknown. Size largest of this genus; four premolars; sagittal crest low and broad; brachyodont; P* two-rooted; antero- posterior diameter of molars greater than transverse. Lower Oligocene (Pipestone Creek). A. maximus Douglass. Size smallest of the genus; P® right triangular; P* equi- laterally triangular in cross-section; molars broader than long; M? and M? possess internal cingula. Lower Oligocene Nis: eae ease See A. mmmus Douglass. Species large; bulle large; nasals narrow and pointed pos- teriorly (Wortman) ; palatonarial border opposite ante- rior cusp of M*; three superior premolars. Upper Oligocene (Protoceras beds) ........ A. auritus Leidy. Species about size of A. latifrons; (known from single molar tooth). Middle Miocene (lower Manchhars). A. sp. Lydekker. REFERENCES. Cope, E. D. 1879. A. On some characters of the Miocene fauna of Oregon. Proc. Amer. Philos. Soe., 18, 63-78. —1879. B. Second contribution to a knowledge of the Miocene fauna of Oregon. Ibid., 370-376. —1881. On the Nimravide and Canide of the Miocene period. U. S. Geol. Geog. Survey, 6, 165-181. —1884. Synopsis of the species of Oreodontide. Proc. Amer. Philos. Soc., 21, 503-572. Douglass, Harl. 1902. Fossil Mammalia of the White River beds of Montana. Trans. Amer. Philos. Soc., new ser., 20, 237-279. Leidy, Joseph. 1850. Descriptions of Rhinoceros nebrascensis, Agriocherus antiquus, Paleotherium proutii, and P. bairdii. Proce. Acad. Nat. Sci. Phila., 5, 121-122. —1852. Description of the remains of extinct Mammalia and Chelonia from Nebraska Territory. In D. D. Owen, ‘‘Report of a geological survey of Wisconsin, Iowa, and Minnesota,’? ete., 534-572. —1854. The ancient fauna of Nebraska. Smithson. Contrib. to Knowl., 6, art. 7, 1-126. —1856. Notice of some remains of extinct vertebrated animals. Proe. Acad. Nat. Sci. Phila., 8, 163-165. —1869. The extinct mammalian fauna of Dakota and Nebraska. Jour. Acad. Nat. Sci. Phila. (2), 7, 1-472. —1871. Report on the vertebrate fossils of the Tertiary formations of the a toa 2d (4th) Ann. Rept.. U. S. Geol. Survey Wyoming and Terr., M. R. Thorpe—New Forms of Agriocherus. 119 Leidy, Joseph. 1873. Contributions to the extinct vertebrate fauna of the western territories. Rept. U. S. Geol. Survey Terr., 1, 14-358. Loomis, F. B. 1920. On Ticholeptus rusticus and the genera of Oreodon- tide. This Journal (4), 50, 281-292. Lydekker, R. 1883. Siwalik selenodont Suina, ete. Pal. Indica, ser. 10, 2, pt. 5, 142-176. Marsh, O. C. 1894. Description of Tertiary artiodactyles. This Journal (3), 48, 259-274. Matthew, W. D. 1909. Faunal lists of the Tertiary Mammalia of the West. In U.S. Geol. Survey, Bull. 361, 91-121. Osborn, H. F., and Wortman, J. L. 1893. Artionyx, a new genus of Ancy- jopoda. Bull. Amer. Mus. Nat. Hist., 5, 1-18. Scott, W. B. 1890. Beitrage zur Kenntniss der Oreodontide. Morphol. Jahrb., 16, 319-395. —1894. Notes on the osteology of Agriochewrus Leidy (Artionyx O. & W.). Proce. Amer. Philos. Soe., 33, 243-251. Wortman, J. L. 1895. On the osteology of Agriocherus. Bull. Amer. Mus. Nat. Hist., 7, 145-178. 120 C. H. Warren—Calcium Carbide. Art. [X.—The Crystalline Characters of Calcwm Car- bide; by C. H. Warren. Something over ten years ago the crystalline charac- ters of calcium carbide were the subject of a thorough study in connection with litigation relative to certain patent claims. The first crystallographers to study the crystalline properties of carbide in detail were the late Professor A. J. Moses and the writer, and they began their observa- tions probably at about the same time. In 1912 Professor Moses proposed, that, at a later date, he and the writer should cooperate in publishing the results of their study. Unfortunately the carrying out of this joint work was delayed, and he who would have been senior author has, to the deep sorrow of all who knew him, ceased forever his scientific work. The crystalline properties of this substance are in many ways so interesting, perhaps unique, that the writer feels it desirable to put them on record, realizing, how- ever, that they will doubtless lack many observations of interest that Professor Moses would have contributed. In the course of the litigation above referred to, Pro- fessors J. P. Iddings and L. V. Pirsson, E. H. Kraus and Doctors F. E. Wright and H. P. Whitlock also studied the carbide. | , Megascopic characters.—Calcium carbide as made in the electric furnace is for the most part a granular or columnar crystalline aggregate of a prevailing black, reddish-black, or reddish-brown, less commonly, yellowish- red or brown color. Natural surfaces sometimes show a bluish or purplish iridescence. The crystalline structure is usually revealed on broken surfaces by the presence of a great number of brilliantly reflecting cleavage surfaces. The cleavages are nearly equal and parallel to three direc- tions at right angles to one another. The granularity of carbide varies widely. In quickly chilled material from the margins of ingots the grain is very fine to invisible. Material taken from the inner parts of slowly cooled ingots, or from carbide cooled in the furnace, may be coarse grained, the individual dimensions of grains being several millimeters or even a centimeter or more. Freshly broken cleavage surfaces when examined with a C. H. Warren—Calcium Carbide. 121 pocket lens show on their surface a series of minute lines or ridges, which run parallel or at 45° to the intersections of the rectangular cleavages. If a cleavage fragment be viewed in a good light, it-may be seen, particularly near the edges where some light penetrates the fragment, that Fie. 1—Sketch of a calcium carbide cleavage fragment. Cleavage is parallel to the three pinacoids and pseudo-cubiec in character. The carbide is polysynthetically twinned; the twinning directions make with the pinacoidal edges angles of approximately 45°, the twinning is therefore pseudo-dodeca- hedral. The twinning lamelle may often be seen in freshly broken frag- ments near the translucent edges. An attempt to illustrate this is made in the figure. The directions followed by the lamelle on any one cleavage face are shown by the figure in the lower corner. there are within the substance series of exceedingly thin lamelle, distinguished by reason of slight differences of color or transparency, which are either parallel, or inclined at approximately 45° to the cleavage edges. The rectangular lines on the cleavage face mark the boundaries of individual lamelle where these emerge on the cleavage surface. The individual grains of carbide appear, there- fore, at the outset to be in no sense simple individuals but highly composite in character, being made up of a series of thin plates united in a definite but complex manner. The accompanying sketch will serve to illus- trate the structures described (Fig. 1). 122 C. H. Warren—Calcium Carbide. Columnar structures (groups of parallel elongate col- umns) are common, particularly in the coarser varieties. The direction of elongation of the columns makes an angle of 45° with the rectangular cleavages. The contact surfaces between individual columns is wavy and irregular. Microscopic character of electric furnace carbide.— Small fragments of carbide were ground down on two parallel sides with fine carborundum or rouge and dry kerosene oil until sufficiently thin to transmit light. Owing to the tendency of the carbide to break and cleave when any considerable degree of thinness is reached, these sections, in general, were not as satisfactory for study as crushed material. Most of the preparations for study were prepared either by crushing small fragments in a mortar under some liquid which decomposes carbide slowly or not at all (dry kerosene oil, a-monobrom-naphthalene or methylene- iodide), and then transferring some of the powder with the liquid to a glass slide and covering the ‘whole with a cover-glass; or a small fragment was carefully crushed and the powder quickly passed through a fine screen (100- 150-200 mesh) on to a glass slide on which was a drop of one of the liquids used, and the whole covered with a thin cover-glass. Color.—The color in transmitted light is purplish-red or lilac-yellow, and less commonly a slightly greenish yellow. Exceedingly thin fragments appear nearly or quite colorless. Pleochroism.—Slight differences of color (pleochroism) for light vibrating in different crystallographic directions may be seen, but only in relatively thick fragments. | Transparency.—The transparency is good in thin frag- ment (0.01 to 0.02). Thicker and larger fragments are subtransparent to translucent. Many fragments are only feebly translucent owing to deep color, inclusions and twinning. Cleavage.—The cleavage is easy and perfect in three directions at right angles to each other, as nearly as can be determined under the microscope. The true rectan- gularity of this cleavage was established by Professor EH. H. Kraus by measurements on the reflection goniometer. Twinning.—The twinning is_ highly polysythetie. Individual cleavage plates, ground very thin, show, par- C. H. Warren—Calcwm Carbide. 123 ticularly between crossed nicols, that the grains are entirely made up of groups of lamella, which run either parallel or perpendicular to, or at an angle of approxi- mately 45°, to the cleavages. The lamelle often wedge out parallel to their elongation, or may end against mem- bers of another set. Different sets are commonly arranged so as to form rectangular patterns. cleavage face) and upon rotation a dark brush moving across the field, the direction of its movement being oppo- site to that of the rotation of the fragment. This indi- eates that, as would be expected from the oblique extine- tion of the grains, the position of the optical elements is unsymmetrical to the cleavages. . System of Crystalliization—tThe double-refraction, the rectangular cleavage and parallel extinction of calcium carbide lead to the-conclusion that the system is either tetragonal or orthorhombic. There was a difference of opinion among the various observers as to which one of the two systems the carbide really belonged to. The euri- ously anomalous behavior of the interference figures is puzzling and difficult of explanation, but in general it might be produced by a complex twinning, be the system of crystallization either tetragonal or orthorhombic. The writer has always been, and still is of the opinion, that without definite proof, it is more in keeping with erystal- lographic philosophy to consider the carbide as of ortho- ~ rhombic symmetry, with a polysynthetic twinning parallel to the diagonals approximately at 45° to the pinacoids: pseudo-duodecahedral). This twinning is mimetic, caus- ing the carbide to appear pseudo-cubie geometrically and pseudo-tetragonal optically. 7 The yellow and less pure carbide, which, as has been indicated earlier, is probably a solid solution with other substances, 1s apparently triclinic. Geometrically (viz. in cleavage) it appears not to differ noticeably from the purplish or purer carbide. C. H. Warren—Calcium Carbide. 127 Reaction with water—tThe effect of slow decomposi- tion of the carbide by water, as seen under the micro- scope, is curious and worthy of note. This effect is best observed if a few thin rectangular cleavage fragments are inimersed in glycerine containing a very little water so as to cause the decomposition of the carbide into acetyl- ene and calcium hydroxide to proceed very slowly and without effervescence enough to disturb the position of the grains. Viewed between crossed-nicols the margin of the grains may be seen to gradually lose the strong interference colors due to the birefringence of the ear- bide, and a rim of feebly birefringent material begins to develop. The corners naturally change more rapidly than the sides so that the unchanged carbide within assumes a circular or elliptical outline, which constantly diminishes in size until the entire grain has changed to _ the feebly doubly-refracting (about 0.008) material, which is calelum-hydroxide. During this change the structural appearance of the grain does not alter, cleavage cracks and twinning lines remaining. After a lapse of a little longer time the substance breaks up, separating along the directions of the cleavages, and finally dissolves in the liquid if there is sufficient water present. The change appears to involve the passage of one erystalline sub- stance to another without the immediate breaking down of the essential crystal structure. In the reaction given by the equation CaC, + 2HOH = Ca(OH), + C,H, we might suppose that perhaps the OH group simply takes the place of carbon atoms, the crystal structure being pre- served intact by the network of calcium atoms, or at least some such mechanism is conceivable. This phenomenon recalls to mind the preservation of crystalline structure in certain zeolites when slowly dehydrated. It also occurs to the writer, that the change of biotite to chlorite, so frequently seen in rocks, where the chlorite seems to sim- ply replace the original biotite, the brown color and strong birefringence of the latter changing to the green color and low birefringence of the former, is also a sub- stitution of certain atoms or atomic groups in the erystal structure, the main features of which remain intact throughout the change. An X-ray study of calcium carbide and its decomposi- 128 C. H. Warren—Calcium Carbide. tion product, could it be carried out, would be interesting in this connection. _ Itmay be remarked that the phenomena above described constitute an excellent micro-test for calcium carbide. Calcium cyanamide.—This substance is formed directly from ecaleium earbide when it is heated in contact with air (nitrogen) at 900°C. and is usually present in commercial carbide. Its crystalline and optical proper- ties were first worked out, we believe, by Professor Moses and are briefly as follows: System rhombohedral. Cleavage rhombohedral, per- fect, angle 74°, calculated from an apparent angle as measured under the microscope of 68°. There is a poor cleavage or parting parallel to the base; rarely shows a twinning, probably parallel to the cleavage rhombohedron. Colorless, index of refraction of ordinary ray 1.60; of extraordinary very high but undetermined. Double-refraction exceedingly strong, at least twice that of calcite, or above 0.85. Optically positive. The chief poimt of imterest is the enormous double- refraction of this substance. Other substances.—In commercial carbide beside cyan- amide, unconverted carbon, crystallized oxide of alumina (corundum), and lime occur as accessories in variable amounts. | Massachusetts Institute of Technology, Cambridge, Mass., April, 1921. ed xf 862, . ‘Incorporated 1890. oe few. of our recent circulars in the various : departments: : Geotony: J-32, Descriptive Catalogue of a Petrographic Col- ». . lection of American Rocks. J-188 and. supplement. _ Price-List of Rocks. | Mineralogy: J-220. Collections: J-225, Minerals by Weight. ee, . J-224, Autumnal Announcements, - Paleontology : J-201. Evolution of the Horse. J-199. Palew- + ozoie index fossils. J-115.: Collections of Fossils. eB cmelogy: J-33. Supplies. J-229, Life Histories. J-230. s Live se of Typical ‘Animals, ete. . 38. Models. eecuescove Slides: J-189. Slides of Parasites. J-29. Cata- =. logue of Slides. sdermy: J-22. North American Birdskins.. Z-31. General * Taxidermy. Human ee J- 37, Skeletons & Models, 7 NATIONAL 1 REVIEW OF SCIENTIFIC SYNTHESIS. Isswed monthly (each ta number (ieee of 100 to 120 Pages), Editor: BUGEMO RIGNANO. 7 = Delage - De Viles - packhelay ~ Batneinn races ceil - Emery = ariniek ; - , bry = - Findlay = Fisher = Fowler = Golgi - Gregory = Harper - Hartog - Heiberg - Hinks - okins-Inigues-Innes-Janet-Kaptein- =-Kaye-Kidd-Langevin-Lebedew-Lloyd Morgan - = Loisy - Lorentz = Loria-Lowell - MacBride = Meillet -Moret-Muir-Peano -Picard - are = Puiseux - Rabaud- Lae Pastor - peed a eee ee x lp text a sapplement containing the French fravsiations of all the articles that : (Wr ite for a ee” sees to the General Secretary of ‘ Office : 43 Foro fnecute: Milan, Italy. wbohers: WILLIAMS & NORGATE- ‘London; FELIX ALCAN -Paris : ~ NICOLA eee Le Boloene WILLIAMS & v3 _ WILKINS. CO-Baltimore. “Ann VI. Ps Foadil Flom, on ihe. A citi Formation not = S ies ee ; Pe R. We Cuanzy.. ree Se = 7 a coy, oe “Arr, 1X, —The » Caystaline Characters of Calcium m ie foe oe? H. WARREN. ofc. ets Meg eS Se "-Eprror: : EDWARD s. DANA. ASSOCIATE EDITORS | So! WILLIAM M. DAVIS AND RE GINALD A. DALY, Se oF CaMBRIDGE, OF ‘Wasrnaron. FIFTH SERIES s es CONNECTICUT. cro t i dollars per year, in advance. $6.40 to countries in the ( Single numbers 50 cents; No. 271, one dollar. tthe Post oor at aoe a Conn. ,, Lei the Act 3 _ reliable. Sc+ Tk = i ee ee ee ee sas = =. = 4 eee : DeF S =i : =~ aes pee w= SREY ; ‘ et tae sg a ee a WILEY BOOKS ~ FOR OIL GEOLOGISTS "Recently Issued 3 = = z om FIELD MAPPING FOR THE On GEOLOGIST By C. A. WARNER, Field Geologist, Empire Gas and Fuel Co., 5 ae Sea eee as Bartlesahe, Oklahoma pts Se ee ee "ag : Only the more important phases of ald meeppan have been considered, - the book giving a general knowledge of the subject and laying a foundation — for the carrying further of detailed work in any particular area. Geologists |} ‘who have had little experience with the methods commonly used in examining ih = a territory not yet drilled will find WarNER’s “(FIELD MapPine” practical and || 143 pages, 414 by 138 Seas Flexibly bound, $2.50. Ready October ISth. ECONOMICS OF PETROLEUM : By JOSEPH E. POGUE, © = Consulting Engineer — A book containing a vast number of helpful. as for iat geologists. and everyone else at all concerned with any phase of the oil question. Charts are included which give at a glance accurate figures and facts dealing with Bt duction, costs, ete. About 350 pages, 6 by 9. “lustrated, Cloth binding. We are always glad to send copies of any Wiley Book for ie Exami-— a nation. Enter your order NOW—for ‘‘Warner” at once—for eee when (78 ready. = eS au me = JOHN WILEY & SONS, Inc. a 432 Fourth Avenue, New York = = London: Chapman & Hall, Ltd SF Montreal, Quebec: Renouf Publishing Company. A589. Qa =. = a THE AMERICAN JOURNAL OF SCIENCE [FIFTH SERIES.] Art. X.—Some Mechamcal Curiosities connected with the Karth’s Field of Force;+ by Wauter D. Lam- BERT, U. S. Coast and Geodetic Survey. By the earth’s field of force is meant the field due to the attraction of the earth according to the law of inverse squares combined with the apparent forces due to the movement of our frame of reference resulting from the rotation of the earth. In general we shall consider the field of force for statical purposes only and then the apparent forces due to the motion of our frame of refer- ence reduce to the ordinary centrifugal force; we thus avoid the complications arising from the presence of the compound centrifugal acceleration or accleration of -Coriolis,? which enters into problems of motion relative to the earth. It is convenient to distinguish between gravity and gravitation. By gravitation is meant the force of mass- attraction only according to the law of inverse squares; by gravity is meant the force of mass-attraction combined with the centrifugal force of rotation. This paper deals exclusively with gravity. As a first approximation, corresponding to the assump- tion that within the region considered the surface of the earth may be treated as a plane, we may consider gravity as constant in amount and as acting in parallel lines. The equipotential or level surfaces will be parallel planes 1 Read at the meeting of the Maryland-Virginia-District of Columbia Sec- tion of the Mathematical Association of America held at Annapolis, Mary- land, December 11, 1920. 2The compound centrifugal acceleration of a particle referred to a set of rotating axes is equal to twice the vector product of the angular velocity of rotation of the axes themselves by the linear velocity of the particle relative to the axes. The compound centrifugal acceleration governs the easterly deflection of a falling body, the rotation of the plane of oscillation of the Foucault pendulum, the direction of the trade winds, ete. Am. Jour. Sct.—F irra Series, Vou. II, No. 9.—SEPTEMBER, 1921. 130 W. D. Lambert—Mechanical Curiosities spaced at equal distances apart for equal differences of the gravity potential. As a second approximation, we may consider the lines along which gravity acts as straight and as all meeting at a common center, that is, the center of the earth. On this assumption the earth is a sphere and the level surfaces of the gravity potential are spheres concentric with it. So many of our ideas about gravity are based, more or less unconsciously, on the conception of parallel planes or concentric spheres that the conse- quences of the fact that these conceptions are only approx- imations to the truth often seem like paradoxes. Much of this paper will be devoted to these apparent paradoxes. The next step in the series of approximations would be to take the level surfaces as spheroids of revolution having a common axis, the polar axis of the earth. Now spheroid is a rather indefinite term, more general than ellupsoid. All ellipsoids of revolution that have their axes nearly equal are spheroids of revolution, but not all such spheroids are ellipsoids. This fact is illustrated by the extreme case of the level surface marking the outermost limit of the atmosphere.* This case was treated by Laplace.® The equatorial radius of this sur- face is 6.6 times the radius of the earth, this distance being such that the centrifugal force of rotation just balances the earth’s attraction at the equator of the sur- face; the polar radius is two-thirds of the equatorial radius. The most curious feature of the surface (see fig. 1) is at the equator where instead of continuous curva- ture, aS on an ordinary spheroid, there is found what seems to be a sharp ridge but is really the intersection of two nappes of the surface at an angle of 120° ; the portions *The familiar paradox that the Mississippi river runs uphill, because its mouth is farther from the center of the earth than its source, may be said to arise from overlooking the fact that the sea level surface and other level surfaces are spheroids and not spheres. The misconception is based on a too literal acceptance of the statement that bodies tend to fall towards the center of the earth. It would be just as logical to say that the ocean lies on a slope, or rather on two slopes, because at the equator it is 13 miles farther from the earth’s center than it is at the poles, as it is to say that the Mississippi runs uphill. *The limit meant is one derived from the classical mechanics of masses. No account is taken of the motion of the molecules of the atmosphere accord- ing to the kinetic theory of gases nor of other questions of molecular dynamics. °* Mécanique Céleste, Book III, Chap. VII, Sect. 47, or in Bowditch’s translation, Vol. II, p. 519. See also Resal, Mécanique Céleste, 2d ed., p. 322, and Helmert, Hohere Geodasie, Vol. II, p. 100. Connected with the Earth’s Field of Force. 131 Fig. 1. | Hl | —_ Limiting Equipotential Surface of the Earth as ! i | sos eoee Analytic Continuation pt Limiting Surface Potential =C | 4 | —— Clguipotential Surface for Potential = L02C i i —-—- Analytic Continuation of above | f | ——— &guipotential Surface for Potential = 0.98 € | ’ Fig. 1.—Limiting surface of the atmosphere and adjacent level surfaces; note the difference in the manner in which the level surfaces around the point A connect with one another in passing from one side of the limiting surface to the other. 3 132 W. D. Lambert—Mechamcal Curiosities beyond the nodal line are inapplicable to the problem for physical reasons. The equipotential surfaces just within the limiting surface show a tendency to ‘‘sharp- edgedness,’’ a tendency that rapidly decreases as we move inwards. The limiting surface is a spheroid by courtesy only, but the surfaces with radii up to 3 or 4 times that of the earth are very passable spheroids, although not exact ellipsoids; in middle latitudes they are depressed below ellipsoids having the same axes. In the problem just discussed the effect of the earth’s deviation from a spherical form was neglected. By intro- ducing just the right distribution of mass we may make one of the equipotential surfaces lying outside of attracting matter an exact ellipsoid; the other surfaces will not be absolutely exact ellipsoids but transcendental surfaces very closely resembling ellipsoids, particularly those not far from the exact ellipsoid.’ The important thing to notice, however, is not so much the question whether the level surfaces are exact ellipsoids, but rather the fact that these level surfaces are not similar; the flattening increases with the distance from the center. Any two given surfaces are farther apart at the equator than at the poles. (See fig. 2.) This corresponds to the fact that gravity is less at the equator than at the poles, the force at a point in a direction perpendicular to two consecutive surfaces being inversely proportional to the distance between them. For the earth a level surface that is 1000 meters above sea level at the equator is about 995 meters above sea level at the poles, a variation of 5 parts in a thousand or one in two hundred. Gravity at the pole is therefore greater than gravity at the equator by about 1/200 part of itself.® *A study of the mathematical equation giving the form of these equipo- tential surfaces will explain the existence of the nodal line. The mathe- matical equation defines surfaces not applicable to the problem in hand for physical reasons. These surfaces are shown by dotted or dashed lines in the figure. * This refers to the surfaces outside of attracting matter. Within a homo- geneous ellipsoid the equipotential surfaces, whether due to mass-attraction alone or to mass-attraction combined with the centrifugal force, are exact ellipsoids. On the subject of ellipsoidal and approximately ellipsoid level surfaces see the author’s Report on Stokes’ Theorem and related methods of deter- mining the Figure of the Earth, probably soon to be issued as a U. 8S. Coast and Geodetic Survey special publication; also Helmert, Hohere Geodasie, Vol. II, p. 92. ®More exactly 1/189 — 0.00529. OR SEY aint Connected with the Earth’s Field of Force. 183 For an example on a smaller scale let us take Lake Michigan, which extends from latitude 41°20’ to 46°00’, and let us suppose the level of its surface to be undis- turbed by conditions of wind, current or temperature. We should then be apt to say that such a surface would surely be level, and so it would be in the proper sense of the word. Eres 2. ; Hic. 2.—Showing the increase in the ellipticity of a level surface with its dimensions and the convexity of the vertical towards the equator. Nevertheless the northern end is 8 centimeters nearer sea level than the southern end.® The elevation of a point above sea level has only a geometrical significance, not a dynamical one, until we know where it is located. That is, Suppose two points nearly at the same elevation; we eannot tell whether water would flow from the one that is at the greater distance above sea level to the one that is at the smaller distance above sea level or vice versa until we know in what latitudes the points are. For the point that seemed higher may lie on a level surface situated imside the surface containing the point that seemed lower. It is convenient in dynamical problems to devise some system of numbering the successive level surfaces and, instead of dealing with the distance of a point above sea level, to deal with the number of the level surface on which it lies. Meteorologists now do something of the sort," but the ordinary surveyor finds the idea of numbered level surfaces, or dynamic heights as they have been ealled, rather abstract, and in many cases an unnecessary refinement. For his benefit the Coast and Geodetic Sur- vey gives the result of its precise leveling in terms of ® This figure is based on an average elevation of the lake surface of 177 meters. If this were greater, the difference between the two ends would be greater also. 10 Por example Bjerknes’ Dynamic Meteorology and Hydrography (Wash- ington, Carnegie Institution, 1910) p. 13. 134 W. D. Lambert—Mechamical Curiosities elevations at the particular latitudes where the bench marks are situated. This has the disadvantage, illus- trated above, of giving different elevations to two ends of a level lake. To allow for this lowering of the level surfaces as the pole is approached and to obtain the actual distances above sea level a correction must be introduced into the direct result of spirit leveling. This is called the orthometric correction. On one line of levels from San Diego to Seattle, which runs much of the way over high ground, the correction amounts to 114 meters, a quantity far from negligible. The direction of gravity which defines the vertical is always perpendicular to a level surface; that is, a line whose tangent at any point takes the direction of gravity at that point is an orthogonal trajectory of the family of level surfaces. Such an orthogonal trajectory is clearly not a straight line but, in the normal case here considered, is convex toward the equator. (See fig. 2.) The astronomic latitude of a place is defined as the angle which the vertical at that place makes with the plane of the equator. Evidently then the latitude at the top of high tower is greater than the latitude of its base. The reduction of astronomic latitude to sea level is part of the ordinary routine of geodetic computations.’” Let us now consider what appears to be a highly artifi- cial problem. Suppose the earth smoothed off so that its physical surface shall coincide exactly with a level sur- face. A particle placed on such a surface is in relative equilibrium even without the presence of friction. But suppose a huge sphere to stand on this level surface. (See fig. 3.) The vector representing the reaction of the surface is perpendicular to it at the point of contact, coinciding in direction with gravity at the point of contact. But gravity acts on the sphere as if the latter were concen- trated at its center, and thus the line of action of gravity is not quite coincident with the direction in which the earth’s surface reacts. Gravity and the reaction are the “See for example Bowie and Avers, Fourth General Adjustment of the Precise Level Net of the United States and the resulting Standard Eleva- tions; U.S. Coast and Geodetic Survey, Special Publication No. 18, p. 49, or Hosmer, Geodesy (New York, 1919), p. 254. * Bowie, Determination of Time, Longitude, Latitude and Azimuth (5th Ed.), U. 8S. Coast and Geodetic Survey, Special Publication No. 14, p. 130. Clarke, Geodesy (Oxford, 1880), p. 101. Helmert, Héhere Geodasie, Vol. IT, p: OS, Connected with the Earth’s Field of Force. 185 only forces and therefore there is no equilibrium but a tendency to move towards the equator. To avoid some of the difficulties suggested at the beginning of this paper that arise in problems of motion relative to axes that are themselves moving, we suppose a constraint applied in the form of a track along the meridian to which the sphere is thus confined. The resultant force along the meridian is indeed small—of the order of magnitude of one one- Fie. 3. ' Fie. 3—Showing the difference in direction between the force of gravity acting on a sphere and the reaction of the level surface on which the sphere rests. millionth of the force of gravity—but a few figures on the effects produced may seem somewhat surprising until we remember that even a small force can accomplish much by long-continued action.'® Suppose the radius of the sphere to be one kilometer and that the latitudes from which it starts are successively 30°, 45° and 60°. The little table shows the journey to the equator divided into thirds and gives the time (in days and hours) taken to cover one, two and three-thirds of the journey and the velocity attained in meters per second. Tnitial latitude 30° Reaches Velocity hate after m. per sec. 20 ees las Sal 10 11 9 4.0 0 1 eal 4.3 % See Appendix A to this paper for the mathematical developments. 136 W. D. Lambert—Mechamical Curtositres Initial latitude 45° Reaches Velocity lat. after m. per see. 30° opr fais 4.3 15 Zs D.1 0 1 Peat 6.1 Initial latitude 60° Reaches Velocity lat. after m. per sec. 40° 10S Ftp 0.0 20 14) 23 6.8 0 13> At 7.5 The table is calculated on the supposition that the sphere rolls without slipping; then about 2/7 of the work done goes into the kinetic energy of rotation, thereby diminishing the amount of energy available to produce velocity of translation. If we imagine a constraint such that the sphere is obliged to slide without friction, it would travel somewhat faster. The matter may be looked at from a slightly different point of view. The sphere really falls in going towards the equator and what body will not fall when it has the chance? What do we mean by falling? Suppose the successive level surfaces are numbered in any manner so that any surface bears a higher number than the one immediately inside of it. A particle falls when it passes from any surface to another surface bearing a smaller number. The original level surface that passed through the center of the sphere at latitude 60° passes above the center of the sphere when the latter has come to the equator, so the sphere has fallen through a distance equal to the distance from its center to that level surface which in latitude 60° passed through its center, or as a simple calculation shows, through 4.0 meters. Perhaps with this way of looking at the problem the velocities at the equator will not seem so surprising. If you will pardon a bit of personal reminiscence, I will tell you what suggested the apparently fantastic problem of the huge rolling sphere. A well-known geologist told me that he had been convinced by geologic evidence that a part or a whole of each continental block has shifted its position in past time by moving towards the equator and in so doing has probably twisted in direction with refer- ence to the meridian. He had been led to think along Connected with the Earth’s Field of Force. 187 these lines by two articles't published quite independ- ently of each other, in which the authors evolved the hy- pothesis of continental creep in explanation of mountain building. If we accept this idea, the inevitable question is: what forces caused this motion of the continental masses 27° Now the continents are certainly not huge spheres rolling on the earth’s surface. If we adopt the floating- erust theory, they would be comparable to bodies floating almost submerged in a liquid magma. If the floating bodies were of almost the same density as the magma, they would float almost exactly level with its surface and could be considered as solidified portions of it, so that, according to a well-known principle of hydrostatics, they would be in equilibrium if the liquid containing them were. But if the floating bodies were lighter and projected above the level surface of the sustaining liquid, there would be forces acting of just the same nature as those that draw the sphere toward the equator.1® The problem of the sphere was given in some detail merely because it was easier to reduce it to a concrete numerical example. The forces acting are in a general way proportional to the average elevation of the continental mass above sea level and to the sine of twice the mean latitude of the continent, and so would be greatest for a mean latitude of 45°. It is not difficult, moreover, to make out, if we are dealing with a floating continental mass longer than it is wide and lying with its greatest length neither along the meri- dian nor perpendicular to it, that there will be twisting forces called into play that would tend to set the axis of greatest length at right angles to the meridian when the mean latitude of the continent is less than 45° or that would tend to set the axis of greatest length along the meridian when the mean latitude is greater than 40°. 44 Taylor, Bulletin of the Geological Society of America, vol. 20, p. 625, 1910. Wegener, Petermann’s Geographische Mitteilungen, 1912, pp. 185, 253, 305. Much the same matter was later issued in book form under the title: Die Entstehung der Kontinente und Ozeane (Brunswick, 1915). 1% An attempt to see whether the supposed shifting of continents con- tinues and is large enough to be perceptible in the course of a few decades was interrupted by the outbreak of the war. The plan was to redetermine transatlantic differences of longitude and to compare the results with earlier ones. 18 For the mathematical developments see appendix B to this paper. 138 W. D. Lambert—Mechanical Curiosities We may, if we lke, consider that the floating continent has fallen in moving toward the equator. In calculating the difference of potential between one position and another, we must take account of the mass of the liquid displaced. | All this is quite speculative of course; it is based on the hypothesis of floating continental masses and on the assumption of a sustaining magma that would, of course, be a viscous liquid, but viscous in the sense of the classical theory of viscosity. According to the classical theory a quid, no matter how viscous, will give way before a force, no matter how small, provided sufficient time be allowed for the latter to act in. The peculiarities of the field of force of gravity will give us minute forces, as we have seen, and the geologists will doubtless allow us - aeons of time for the action of the forces, but the viscosity of the liquid may be of a different nature from that postu- lated by the classical theory, so that the force acting might have to exceed a certain limiting amount before the liquid would give way before it, no matter how long the small force in question might act. The question of viscos- ity is a troublesome one, for the classical theory does not adequately explain observed facts'’ and our present know- ledge does not allow us to be very dogmatic. The equa- torward force is present, but whether it has had in geologic history an appreciable influence on the position and configuration of our continents is a question for eeologists to determine. At any rate it may be consid- ered as one of the mechanical curiosities with which this paper deals. | We do not, however, need to.deal with hypothetical rolling spheres or floating continents in order to find room for the manifestation of peculiarities of the earth’s field of force. We can set up in the laboratory or in the field a comparatively small instrument that will give not merely qualitative evidence of these peculiarities but accurate measurements of them. Let us consider a rod suspended at its middle by a deli- cate fiber. The rod is loaded at both ends so that as 1 Jeffreys, The Viscosity of the Earth, Monthly Notices of the Royal Astronomical Society, vol. 75 (1915), p. 648, and vol. 76 (1915), p. 84. Michelson, The Laws of Elastico-Viscous Flow, Journal of Geology, vol. 25, p. 405, 1917, and vol. 28, p. 18, 1920. Connected with the Earth’s Field of Force. 189 much as possible of its weight may be concentrated there: for simplicity of explanation we shall suppose an ideal case in which the entire weight is divided equally between the two ends and concentrated there. This simple affair, rod and fiber, is the schematic form of the Eétvés torsion balance of the first type (see fig. 4).15 Now suppose iG. 4: v4 P O P’ Fig. 4.—Schematic form of the Hotvés balanee, first type. the earth’s field of force to be normal and the suspended rod to hang in a vertical plane coinciding neither with the meridian nor with the prime vertical. Let us disregard *% For the description and use of the Eodtvds balance and the numerical results obtained with it the following articles may be consulted. Each arti- cle in the list is given a letter by which—to save space—it is hereinafter referred to as needed. A. Hotvos, Untersuchungen iiber Gravitation und Erdmagnetismus; Wiede- mann’s Annalen der Physik und Chemie, Vol. 295, new Ser. 59 (1896), p. 354, Also the following articles by Eotvés in the Proceedings of the Con- ferences of the International Geodetic Association: Budapest meeting (1906), Vol. I, p. 337. Cambridge meeting (1909), Vol. I, p. 319. Hamburg meeting (1912), Vol. I, p. 427. Brillouin, Sur 1’ellipticité du géoide dans le tunnel de Simplon; mém- oires présentés par divers savants 4 1’Académie des Sciences de 1’Insti- tut National, Vol. 33, No. 3. F. Soler, Primi Esperimenti con la bilancia di Eétvés; Memorie del Reale Istituto Veneto di Scienze, Lettere ed Arti, Vol. 28, No. 8 (Venice, WOE G.. Aa Prima Campagna con la bilancia di Edtv6s nei dintorni di Padova; Reale Commissione Geodetica Italiana (Venice, 1914). H. Soler, Seconda Campagna con la bilancia di Hétvds, Reale Commissione Geodetica Italiana (Padua, 1916). I. For a good brief account see Bouasse; Géographie Mathématique, ; Paris, 1919, p. 351. HOW 140 W. D. Lambert—Mechamcal Curiosities for the moment the torsion of the suspending’ fiber. Under the influence of the earth’s field of force the rod tends to turn into the plane of the prime vertical, because in so doing it falls. How may it be said to fall when the height at which the center is suspended remains unchanged? Let us consider the curvature of the sec- tions of the level surfaces in the meridian and in the prime vertical. Itis easy to calculate that (in the normal case) the curvature of the meridian section 1s a maximum and the curvature of the prime vertical section a mini- mum. ‘The two sets of traces of the level surfaces on the planes of meridian and prime vertical are shown in fig. 5, the prime-vertical traces being represented by full lines. The level surfaces are arbitrarily numbered with the numbers increasing outward, which corresponds to values of the potential increasing with height. The line PP’ represents the suspended rod of the EKotvos balance. We see that its ends (where the weight is concentrated) are in the surface numbered ‘‘3’’ when the rod is in the meridian but are in the lower-lying surface marked ‘‘1’’ when the rod is in the prime vertical. Thus there must be a force tending to swing the rod from high to low, or towards the prime vertical. The same thing may be seen from a direct consideration of the forces acting. The moment of these forces comes out 5 ee 1 iL mt sin 20 7 ‘= a x) In this expression 2m is the mass of the rod, 2/ its length, # the angle between the plane of the rod and the meridian, f the intensity of gravity, which acts vertically at the center of the rod, and BR and N are the radii of curvature of the meridian and prime vertical sections respectively. If we substitute for R and N their values in latitude ¢, there results for the turning moment very nearly? tial a In this expression « is the ellipticity of the earth and a its equatorial radius. For Kotvos’s apparatus we may ef cos’ sin 26. The turning moment is zero for either 6—0° or g=90°. The former value, corresponding to the rod in the meridian, gives unstable equilibrium. | In the prime vertical equilibrium is stable. Connected with the Earth’s Field of Force. 141 take m= 40 grams and / — 20 centimeters. With known values of « and a the maximum turning moment (for 6 — 45° and ¢—0) is 1.67 x 10~* dyne-centimeters. In latitude 45° the maximum turning moment is half of this. Fig@. 5. , / \ \ / t / \ \ { ' Us 1 : \ \ ) TROY He ea Cs Oe Naya Net ! het t | | 1 eee | ae OP web S43 Fie. 5.—Sections of level surfaces in the meridian (dotted lines) and in the prime vertical (full lines); shows that the ends of the balance PP’ are lowest in the prime vertical. This moment is certainly not large? but, given free play, it would swing the rod into the prime vertical. It is opposed by the torsion of the fiber, but fibers may be found strong enough to support the rod and yet so yield- ing that the minute forces of the earth’s field will cause a measurable deflection of the rod.71_ The apparatus, torsion-head and all, is turned as a whole into various azimuths and the deflection of the rod in these positions with reference to the position of no torsion is read off on a telescope and scale. From these readings there can be deduced by a process too long to give here the values of Se, where R and N represent now the minimum and maximum radii of curvature, which do not always—I might rather say ‘‘do not ever’’—coincide with the radu 2 Tts size may be perhaps made more vivid by the following comparison. A five-cent piece weighs about five grams. Take about a fifth of its weight and you have a gram. Take the weight of about a thousandth of a gram and you have a dyne. Our moment was about one ten thousandth of a dyne-centimeter. The distance factor was forty, so the force factor was only one four-hundred-thousandth of a dyne, one four-hundred-millionth of a gram, one two-billionth part of the weight of a five-cent piece. "1 See references on a preceding page. Art. A, p. 368; B, p. 340; H, p. 21. 149 W. D. Lambert—Mechanical Curiosities in the meridian and the prime vertical, as we have been supposing. The directions of maximum and minimum curvature are also found by the balance. ‘These curva- tures may be interpreted in terms of the second deriv- atives of V, the potential function of the gravity field.?? If we take rectangular axes, the 2-axis being vertical at the center of the balance, an instrument of the first type will give the numerical value of as Me cS a av On Oy? dx Oy The EHotvos balance of the second type has its masses at the two ends of the rod at different levels, the counter- poise of the one loaded end of the bar being a suspended weight (see fig. 6). Without going into details it may be said that this balance brings into play forces derived from the change in the direction of gravity with elevation, Fic. 6. Zz Fic. 6.—Schematic form of the Hotvos balance, second type. * See references in footnote on a preceding page. Art. A, p. 355. Art. I, p. 317 or Helmert, Hohere Geodasie, Vol. II, pp. 35-40. Connected with the Earth’s Field of Force. 1438 the same forces that make one end of Lake Michigan apparently higher than the other and that tend to draw - the rolling sphere or the floating body towards the equa- tor. With forces of this type are connected the deriva- tives SON Muay’ GaN Oe det 1 dyads and a balance of the second type enables us to find the numerical value of these derivatives. What may be surprising at first is that the observed values of the second derivatives seem to bear absolutely no relation to the theoretical values. Here is a compari- son expressed in two tables. The x-axis is in the meri- dian with its positive end towards the north; the y-axis has its positive end toward the east. One table gives the theoretical values for our assumed normal case with maximum curvature in the meridian, minimum in the prime vertical, and with a line of force lying in the meri- dian plane and convex toward the equator. The other table gives the values at several stations near Padua, Italy, as observed by Professor Soler in his ‘‘Seconda Campagna’’ (footnote, p. 139, reference H). The stations are fairly close together, so we might expect the values of the derivatives to agree pretty well with one another and with the theoretical values for latitude 45° (the latitude of Padua is 45° 24’). The unit of the table is one 10° C. G. S. unit, that is, the tabular values are the real values multiplied by an American billion (10°): Normal Values of the Second Derivatives of the Gravity Poten- tial, V. MOM aeneO 2 COGS Wnts) a er Seer ye aN nls i OM NOx? et On Oy du Oz dy dz 0° ule 0 0 0 15° 40.7 0 at 0 30° eA 0 417.0 0 45° + 5.0 0 + 8.1 0 60° Us 0 +70 0 75° Lago 0 tt 4 4 0 90° ab 7010 0 0 0 144 W. D. Lambert—Mechamical Curiosities Values of the Second Derwatwes of the Gravity Potential Observed near Padua, Italy. (Unit = ones (©. C25, Unita Newel eV oy) Vv BEG av Station Oy" Ox” dx dy dx dz dy dz I + 14.62 eG = ALO ee iu + 8.39 + 6.78 = Foe aco III + 17.31 — jb == 1452 = 21,90 x + 41.58 — ().25 eo + 4.59 XI —— IAs + 4,74 + 0.18 —— ona XII + 37.93 aan 1h 3) + 1.16 le a XIII © +. 10.92 = Dod —= O26 =e XIV + 5.74 — Fe + 16.65 eee These values are not rare exceptions due to very abnor- mal local conditions. It would be easy to find still more erratic-looking observations.”* The specimen given may be taken as fairly typical. Nor are these values the results of observational blunders. Repeated observation in the same spot reproduces consistently the same value and the results check with pendulum observations and with the observed deflections of the plumb line deduced from a combination of astronomic and geodetic opera- tions. The details of the connection between these three kinds of results would take too long to explain here.** These peculiar-looking results are simply a numerical illustration of what the text-books tell us—that while the potential function and its first derivatives change contin- uously in the passage through discontinuities in density, the second derivatives are discontinuous whenever the density changes discontinuously. Akademie der Wissenschaften in Wien, math-naturw. Klasse, session of Jan: 8, 1920; reported in the Akademischer Anzeiger no. 1. Am. Jour. Sct.—Firtu Series, Vow. II, No. 9.—SEpTEMBER, 1921. 10 : 146 W. D. Lambert—Mechanical Curiosities (2) The smooth lake with different elevations for its two ends. (3) The tendency of large bodies to ‘‘fall’’ towards the equator. (4) The tendency of a rod suspended horizontally like the Eotvos balance to ‘‘fall’’ by twisting about the supporting fiber. | (5) The existence of great local irregularities in the curvature of the level surfaces and the interesting possibilities that the study of these irregularities seems likely to offer. APPENDIX A. Motion of a Sphere under Gravity on an Equipotential Surface. The general problem of a sphere rolling without slipping on a rotating surface of revolution, that surface being one of equilibrium for the attraction of the matter contained within it combined with the centrifugal force of rotation, would be somewhat complicated. In treating the general problem it would be a legitimate procedure, though not necessarily the easiest one, to treat the sur- face as without rotation provided the following additional forces were taken account of: (1) the centrifugal force of rotation; (2) the compound centrifugal acceleration. To obtain the resultant of these additional forces an integration would usually be required. In the restricted problem proposed, where motion is confined to the meri- dian, the procedure suggested is evidently the simpler (1) because the effect of the ordinary centrifugal force is implicitly contained in the gravity potential used; (2) because the compound centrifugal forces do not affect the motion when the latter is confined to the meridian.”® Let 6 denote the radius of the rolling sphere. Consider the locus of the points at a distance b from the level sur- face on which the sphere rolls, the distance being meas- ured outward along the normals to the level surface. For definiteness, let us call this new surface to which the center of the rolling sphere is evidently confined, the parallel surface and let ds be an element of meri- dional are of this parallel surface, s being reckoned from the equator toward the pole. 2° For the equations for motion relative to the earth, see Routh’s Advanced Rigid Dynamics (5th Ed.), p. 27, or similar works. Connected with the Earth’s Field of Force. 147 Let Z be the component force acting on the sphere through its center normal to the parallel surface. From the manner in which the latter is constructed it is easily seen that the line of action of Z is also normal to the level surface, and let X be the component of force acting perpendicular to Z in the plane of the meridian, and posi- tive when toward the equator. The attraction of the earth and the centrifugal force of rotation, both of which act on the sphere as if its mass were concentrated at the center, are included in X and Z. Let f denote the force of friction at the point of contact; f evidently is directed along a tangent to the level surface and parallel to X; it is the only force having a moment about the center of the sphere. Let A denote the reaction of the level sur- face at the point of contact. Resolving the forces along tangent and normal, we find?” a’ —m—=,=X+f (1) Te R= 0 and taking moments about an axis through the center and perpendicular to the meridian Q’ — mk ee ie (2) where m is the mass of the sphere and & its radius of gyration —./2b. Eliminating between (1) and (2) gives d’s Da eel 1 se (3) Let ge be the intensity of gravity at sea level at the equator; then g, the intensity in latitude ¢,may be written g=ge(1+ B sin’ >), (4) B being a constant, and it may easily be shown” that a, the change in the direction of gravity for elevation b above the level surface, is given by a= ° 8 sin do, (5) r being the radius vector of the earth. The direction The general treatment of a sphere rolling on any surface is given in Routh, Advanced Rigid Dynamics (5th Ed.), p. 143. ae Clarke, Geodesy, p. 101. Helmert, Héhere Geodasie, Vol. II, p. 98. 148 W. D. Lambert—Mechamical Curiosities of gravity coincides with the normal at the level surface; at the parallel surface the components of force along the tangent and normal are X=mg’ sim a, FT = Ig Coss, or since ais small, K == migra Z=mg’ (6) in which g’ is the intensity of gravity in latitude ¢ and elevation b. The latitude ¢ in formula (4) is usually taken as the geographic latitude, but to the same order of accuracy as is implied in equation (4) we may use any other latitude, as the geocentric or the reduced latitude, or we may put o=-, a being the mean radius of the meridian; to the same order of accuracy a may be put for penta (6s) ‘and g g may be taken as constant. With these substitutions (4) becomes E Bb — = ji ee — y' sin 24, LS i = 5 sin 26, (7). ¢ : 4 b* B b ! g being written for 7 See i Multiplying both sides of (7) by ae and integrating and determining the constant so that “#0 when ¢=y, where y is the initial ere gives (a) =e — (cos 2 — cos 2y) = c” (sin? y — sin’ >) (8) Equation (8) is similar to the equation for the motion of a pendulum where the vibration is not restricted to. infinitesimal ares. To integrate (8) put sin 6= sin y sin 9, whence (8) becomes do es a OE. V1 — sin’ y sin’ 0 This may be integrated in terms of the elliptic integrals,. | Be ectes with the Earth’s Field of Force. 149 and if ¢ be reckoned from the time when ¢ — Vaile Cys when 6— 7/2, we find ies 2 EG sin 7) — F'(6, sin » | (9) where the F' denotes an elliptic integral of the first kind with modulus sin y; or in expressing ¢ in terms of f, OB==SS070,.7 (Ge) = en (ct) mod. sin y (10) Ben pe? B= 0.00529, g’ = 9.8 meters per sec. and a= 6,368,000 meters. For the sphere supposed in the text b 1000 a These values give, for the second as unit of time, For numerical values we have for the sphere ¢ = 0.000001351. The linear velocity (v) is ie , or by (8) v=acYV sin? y — sind ac = a ¥ 008 2b — cos 2 y. (11) With the above numerical values | v = 6.09 ¥ cos 2. ¢ — cos 2y in meters per second. The table given in the text (pp. 135-6) is readily com- puted from (9) and (11). ! APPENDIX B. The Effect of the Earth’s Field of Force on a Floating Body. As a simple example let us consider a sphere of radius r (fig. 7) and density o floating in a liquid of density p, the outer surface of which forms a portion of the geoid. From the center of the sphere draw a normal to the geoid (conceived as continued into the sphere) and take the intersection of the normal with the geoid as the origin of a system of rectangular coordinates, with 2-axis coinci- dent with the normal, the positive direction being upwards and with the wv-axis tangent to the geoid in the plane of the meridian, the positive direction of x being towards the equator. The forces acting on the sphere are the fluid pressure on its submerged surface and the pull of gravity. 150 W. D. Lambert—Mechamical Curiosities The fluid pressure on any element of surface being normal to the surface, has no moment tending to turn the sphere about its center. Gravity acts as if the sphere were concentrated at its center and does not produce any i Direhe ye 3 Fic. 7.—Coordinate axes for the problem of the floating sphere. moment about the center. We shall suppose that the sphere is submerged to such a depth that the pull of gravity along the g-axis just balances the e-component of the fluid pressure, so that the forces acting have a zero component along the ¢g-axis; we suppose also that the field of force is symmetrical with respect to the meridian, so that there is no component along the y-axis. We are interested chiefly in determining whether or not the case of the floating sphere may resemble the case of the rolling one to the extent that there is a small component directed along the z-axis and toward the equator. Consider the pressure of an element P of the spherical Connected with the Earth’s Field of Force. 151 surface, whose coordinates are (x, y, 2) and on Q, the element symmetrically situated and of equal size, whose coordinates are (—w, y, 2). If the intensity of pressure at @ is greater than the intensity at P, then, so far as these two elements are concerned, there will be a resultant pressure tending to move the sphere towards the equator. The intensity of pressure at any point of a homogeneous liquid in equilibrium is (V—V,)p, where V is the potential of the field of force acting on the liquid, V, is the value of V for the free surface—here the geoid—and p is, as before, the density of the liquid. The potential V may be considered as consisting of two parts, (1) the part due to the earth itself; this we shall consider as normal, i. e., such that the geoid is a spheroid of revolution with an ellipticity equal to the mean ellipticity of the earth; (2) the part due to the attraction of the sphere; the direct attraction of the sphere is obviously symmetrical about the z-axis; there is also a small indirect effect due to the slight heaping up of the liquid around the sphere owing to the attraction of the latter; this effect may also be taken as symmetrical about the e-axis.2® The effect of that part of ‘V due to the attraction of the sphere is therefore the same at P and at Q and cancels out as far as the resul- tant pressure is concerned. In calculating this resultant pressure we may therefore use for V simply the normal part of it, or that due to the earth alone. We shall assume that the normal part of the gravity potential may be represented by a polynomial of the second degree in 4%, y, and é, or V-V,=-g 2tav+byY+te#+2huz (CL) The absence of terms in x and y is explained by the fact that the direction of the vertical at the origin coincides with the z-axis. The absence of terms in wy and yz 1s explained by the fact that the w-axis is in the meridian, which is a plane of symmetry. The coefficient g, is the intensity of gravity at the origin; the other coefficients 2 There is a very slight deficiency in symmetry in this indirect effect, because the attraction of the sphere on the liquid in any given direction draws the liquid from a region where gravity is slightly different from what it is in a region symmetrically situated with respect to the z-axis. The effect of the asymmetry is only a small part of the whole effect, which is itself small, and so the effect of asymmetry may safely be neglected, even in comparison with the minute quantities involved in the discussion. 152 W. D. Lambert—Mechanical Curiosities also have physical interpretations.*° Thus ee Cee pis (2) oawk bh oK where R and N are respectively the radii of curvature of the earth in the meridian and prime vertical. The quan- tity c is connected with a and b by the relation 2(a+b+c)=-47k8 +2 (3) In this equation & denotes the gravitation constant and o the angular velocity of the earth about its axis; 6 denotes the density of matter at the point considered, 1. e., 50 for points above the geoid and 6p for points in the liquid. Equation (3) is really a modified form of Lap- lace’s equation or of Poisson’s equation, according as 5 = 0 or =p», the modification being the term in «?, which arises from the difference between gravity and gravita- tion already mentioned (p. 129). The quantity h serves to measure the rate of increase in gravity in going from the equator towards the poles. Evidently by Taylor’s theorem for three variables oV ae | cas a where the subscript zero indicates the value at the origin. If g denotes the intensity of gravity at any point in the field, nn (OM 4 oe y=) +) es or by differentiating with respect to a, 99 _aV eV, BV OV , OV OV | 1 Oa dx Gx ! Oy dydu ' dz Dydz’ * Helmert, Hohere Geodasie, Vol. II, Chap. I. Hétvés bases the theory of his balance on an expression for the potential similar to (1) but contain- ing terms here omitted because of symmetry. The values of a and b do not depend on any property of the gravity potential as such; similar expressions hold good approximately for any field of force having a potential and sym- metrical in the way here supposed. Equation (1) would be exact for the field of force due to gravity in the interior of a homogeneous rotating ellip- soid; even in cases where additional terms would be needed to give an adequate expression for V, the effect.of these terms for the case here treated would be nearly evanescent for reasons of symmetry. Connected with the Earth’s Field of Force. 1: Or Co for the origin this gives L755), = Lecae ae], or since = | = 0: we get ~ [55], = Lege, = 2% But | ie Ey tae ay a where ¢ is the latitude. As in Appendix A 0) : Da = (7F 6 Si 2¢, where ge denotes gravity at the equator and 6 is a constant of the gravity formula = 0.00529 nearly. With sufficient accuracy we may substitute g, for g so that we get finally sp pallens Zia 2h =sZ B sin 26 (4) The. component of pressure along the w-axis, px, 18 evidently given by pe = — ff p cosa ds, (5) where » is the pressure on the element of dS of the sub- merged surface, and a is the angle between the external normal to the surface and the a-axis; the integration extends over the entire submerged surface. If we take points in pairs like P and Q in the figure, the two values of cos a are numerically equal but opposite in sign, and by writing (V—V,) p for the pressure, noting that cos « dS = dy dz and using V with subscripts P and Q to indl- cate the values of V at these points, we find i — aye (V, — V,.) p dy dz. (6) The integration in (6) extends over a section of the sphere by the ye-plane, the bounding curves being the projection of the ‘‘water-line’’ on the yz-plane and that 154 W. D. Lambert—Mechanical Curiosities part of the great-circle section of the spherical surfaces that lie below the ‘‘water-line’’; the element of area dy dz is to be treated as positive. The fact that the portions of the ‘‘water-line’’ on the two sides of the yz-plane do not have quite the same projection upon it will be dealt with later. Neglecting the difference between the two projec- tions we have from (1) Bn ala Meer as (Maes (7) The x is, of course, the positive x of P; the 2 is essentially negative. Thus it is seen that p< is essentially positive, since his positive. It is evident that this must be so, for gravity is greater at any given depth on the poleward side of the sphere than on the equatorward side, so that pressure must be greater also. Using (7) we get pe = — bhp f fe dy de (8) It may be noted that x dy dz is the volume of an elemen- tary prism and that 2x dy dz is the moment of this prism with respect to the xy-plane. If we call zg; the depth below the zy-plane of the center of gravity of the volume considered, and vu; the entire volume itself (on both sides of the yz-plane) De So ep Us 2. (9) The volume v; is nearly the entire volume of the sub- merged portion of the sphere, differing from it by the small volume between the surface formed by the projec- tion lines of the ‘‘water-line’’ and the surface of the geoid. This small volume is zero in the ordinary theory of float- ing bodies which treats the free surface as plane. The quantity 2; corresponds to the depth of the center of buoyancy in the ordinary theory. The pull of gravity on the sphere is not exactly along the z-axis, since the direction of gravity at the center C is not quite the same as at the origin. The x-component of the pull is the mass of the sphere multiplied by the value of = at the center, or calling gx the pull of gravity, v the volume of the sphere, and ¢ the g-coordinate of its center, we get gx = 2aovht. (10) Connected with the Earth’s Field of Force. 155 The resultant X, of all forces along the z-axis, is Px a 9x, Or X= 2h (ove — pv, 2) (11) It is easy to show that px is numerically greater than gx, or that the resultant force is towards the equator, gs and ¢ being essentially negative. The effect of the lack of symmetry with respect to the yz-plane, which we have so far ignored, is easily seen to be negligible. The equation of the free surface is found by putting the right-hand side of (1) equal to zero. If # or y be taken as a small quantity of the first order, z is easily seen to be of the second and 2? of the fourth order, so that we may write for the point A, whose coordinates are (a, 0, 21), a x" ax Qhe eo en Jo (1+ Jo ) For the point B, approximately symmetrical, with coordinates (a, 0, 22) Qhex 22 (i= *) Jo Jo Benes shar If in (12) we take x equal to r, the radius of the sphere, then, (12) Pen, lie be PZB re ‘GG, cath R? is the maximum possible depth of the strip on which the pressure is unbalanced; the maximum width in computing (6) or (8) is 2r, and the maximum pressure, since the strip is at the ‘‘water-line,’’ is evidently less than % (depth)? X width X (go p), 1. e., less than 4 (7) Jopt (13) The quantity (13) is seen to be quite negligible when compared with (9) or (10), both on account of the addi- tional factor 8 and a factor of the order (3): This unbalanced pressure, such as it is, is furthermore toward the equator. 156 W. D. Lambert—Mechanical Curiosities To form a numerical estimate of the equatorward force let us take o—=2.7 and p= 3.2; these figures correspond roughly to the case of a mass of rock floating in a heavier basic magma. By neglecting the curvature of the earth and the vertical variation of gravity, it is easily seen that the spherical mass of rock will float with one-half of its radius above the liquid,* that is, with 5/32 of its volume above the liquid and 27/32 below, that is, with ¢=- 2 we find also 2; = = v= 47r, and = 2a7r. “Thererone by (4) and (11) | s Jor sina gh The value r=38 kilometers corresponds with an aver- age elevation above the liquid of 833 meters, which is about the average elevation of the land surface of the earth; on the floating-crust theory the elevation of the land above the sustaining magma would exceed this amount. For this case the force X is 1/3000000 part of gravity for ¢= 45°. This force X, though small, would, if acting continuously without resistance, bring the sphere from latitude 45° to the equator in about three weeks.*” If the preceding discussion be examined, it will be noticed how little use has been made of the spherical form of the floating body. A symmetrical body, like a paral- lelopiped, if placed symmetrically with respect to the meridian, could be substituted in the discussion in place of the sphere. The parallelopiped would not be attracted by the earth exactly as if the former were concentrated at its center of gravity, but the error in assuming that it would be is very small. The chief difficulty arises from the fact that the resultant pressures have moments about the center of gravity of the parallelopiped; but it can be shown that these do not affect the general validity of the *1 This is simply a convenient coincidence; the problem of the floating sphere requires the solution of a cubic equation. *” Tf the sphere were not constrained to float along a meridian, the deflect- ing force of the earth’s rotation would cause its path to take a curious wavy or looped form resembling a trochoid; if the sphere were to start from rest, the general direction of its advance, apart from the loops or undulations, would at first be at right angles to the meridian. The discussion of the exact form of the path is not necessary for the matter in hand, since the time needed to reach the equator is of the same order of magnitude, whether the sphere be confined to a meridian or not. Resistance would make the sphere move more nearly in the original meridian. Connected with the Earth’s Field of Force. 157 general conclusion, namely, the existence of an equator- ward force. For a parallelopiped the equatorward force is approximately proportional to the average elevation of its upper face above the surface of the fluid. For a body of irregular shape the existence of such a force may be inferred by a comparison of the potential of such a body floating at the equator, with its potential at some other latitude; the potential of the displaced fluid must be included in the calculation. The force itself may be conveniently evaluated by using for calcu- lating the pressures the familiar transformations. SV cosa d8 ff fp, x dy a The integral on the left is extended over the submerged surface and also, merely to form a closed surface, over the cap formed by the geoid surface within the solid, the cap being bounded by the ‘‘water-line.’’ The integral on the right is a volume integral over the solid bounded by the submerged surface and by the cap.*° The statement on page 137 with regard to the force which tends to turn a floating body, so as to bring its axis of length into the prime vertical in low latitudes and into the meridian in high latitudes applies to a body in general conforming to the curvature of the earth and lying oblique to the meridian, with a uniform elevation of its upper surface above the surface of the liquid. In low north latitudes the northern end, being nearer to latitude 45°, where the equatorward pull is a maximum, would be drawn toward the equator more strongly than its southern end. This would tend to bring the axis of greatest length into the prime vertical. In high north latitudes (above 45°) the southern end would be drawn more strongly toward the equator and the force would tend to bring the axis of length into the meridian. This force resembles somewhat the force acting on the bar on an [Kotvos balance, but has a different cause. The motion of matter toward the earth’s equator would, of course, have an effect on the position of the earth’s axis of rotation. It has been assumed that the masses involved were negligible in comparison with % See almost any account of the potential function, as for example Peirce’s Newtonian Potential Function, 3d Ed., page 66. 158 W. D. Lambert—Mechamcal Curiosities that of the earth,?* and the effect in question has not been considered. Its existence, however, does not invalidate the argument for the equatorward force. The effects dealt with have been of the order g8 r), where r is the greatest dimension of the body involved and R the earth’s radius. The ratio of the mass of the body to that of the earth would be of ie order (=) that is, we have considered quantities of the first order in a but have He lected quantities of the third order. R. 8. Lull—Fauna of the Dallas Sand Pits. 159 Arr. XI.—Fauna of the Dallas Sand Pits; by Ricuarp Swann Lui. One of the characteristic features around Dallas, Texas, is the sand pits opened in the remnants of ancient flood plains on either side of the valley of the Trinity River. Several of these have been operated for many years, and in addition to the sand and gravel they have yielded as a by-product an interesting Pleistocene fauna. This is as yet incompletely known, largely through lack of appreciation, as the material has been often cast aside on the dumps to be destroyed by weather- ing. Professor Kllis W. Shuler, of the Southern Meth- odist University, has, however, with a high realization of their value, endeavored to save such specimens as have lately come to light, and to him I am indebted for the privilege of description. There have thus far been recorded, since the first speci- men was noted in 1887, the skulls of no fewer than thir- teen elephants, one of which, bearing splendid tusks, although with the cranium largely restored, was on exhi- bition in the old Peabody Museum at Yale (Cat. No. i023) ¥ EM Shuler 1913) (pl, 12). This: andother specimens have been identified as Elephas amperator. In addition, Shuler’ lists: ‘‘Bones of Hquus scotti, the Texas horse; an ancient bison, species undetermined; bones of smaller animals, as yet undetermined; and bony scutes from the skin of the giant sloth.’’ ‘‘Most of the specimens,’’ he goes on to say, ‘‘are found in the sand pits just underneath the covering of clay or near the base of the pit.’’ The sand pits of Hast Dallas are 50 feet above the Trinity. The date of deposition of these sand pits may be taken as Pleistocene ..., since they are the highest river deposits in which fossils of Pleistocene mammals have been found. ... Fossils are found occasionally in the lower sand and gravel pits, but such specimens show the effects of transportation by stream action.’’ A section of the Lagow sand pit, Hast Dallas, whence the present consignment of fossils has come, is thus described by Professor Shuler (letter of March 3): *H. W. Shuler, Univ. Texas, Bull. 1818, 26, 28, 1918. 160 R. S. Lull—Fauna of the Dallas Sand Pits. 2 ft... ge Top soil. Medium grained sandy loam. Dark red to ) bilge i .ccos 8 Sie CR ee eee eee about 2 7 Sandy clay, hard, tenacious. Red.:............. about 3 Fine sandy clay with light calcareous segregations and streaks. Texture of sand varies. Color yellow. Fossils: antelope, bison, mammoth............ about 2 10 Fine to coarse clean white sand and gravel. Gravel usually under 1 inch. Cross-bedded. Foreset beds not over 12-14 inches, usually 3-4 inches. Fossils usually found at bottom, especially larger bones. Bones clean and usually white or cream in color. MammothOcamel 32:2 8 Se erie Oa! ek: ...about 14 Austin chalk. SUMMARY OF MATERIAL. Class Mammalia. Order Carnivora. Family Felide. Subfamily Macherodontine. Smilodon fatalis (Leidy). Cranium. Order Artiodactyla. Family Cervide. Odocotleus sp. ‘Humerus, antler. Family Antilocapride. Tetrameryz shuleri, gen. et sp. nov. Cranium, maxillary. Family Bovide. Bison allent Marsh. Left mandible. Family Camelide. Camelops huerfanensis dallasi, subsp. nov. Skull, ete. Camel, gen. et sp. indet. Cannon-bone. Order Perissodactyla. Family Equide. Equus. ef. fraternus Leidy. Cannon-bone, humerus. Order Proboscidea. Family Hlephantide. Subfamily Mammotine Elephas columbi Falconer DESCRIPTION OF MATERIAL. Smilodon ef. fatalis (Leidy). (Fie. 1.) A finely preserved occiput of a large sabre-tooth cat is present, bearing the catalogue number 1.52, Southern Methodist University collection (plesiotype). The speci- men shows signs of stream transportation and is there- fore apparently from the lower level of the Lagow sand pit. ) Its affinities with Smilodon are clearly shown by the relatively great vertical extent of the mastoid processes, R. 8. Luil—Fauna of the Dallas Sand Pits. 161 together with their being directed downward and for- ward so that the auricular fossa is nearly closed below, whereas in Felis it is wide open and the vertical extent of the mastoids is relatively slight. The occipital condyles are also Smilodon-like and show a great habit- ual range of vertical movement than in Felis. All this is correlated with the great development of the sterno- mastoid muscle in Smalodon for use in striking its prey, and is highly diagnostic of the genus. SO SOS WS BSE f- ESSE AS ISSES SHAQ ~ s ES Ne yy SNR: S - DOSEN TOONS ANNs = S Te aig gah A ae > ‘ Ss ra be yp ) Sey iN A: ca () Fett A) ce? 7. ca Bs Ses 23 wh %. ols Fic. 1.—Smilodon ef. fatalis (Leidy). Cat. No. 1.52, 8.M.U. Oblique aspect of cranium. << 4. But one species of Smilodon has been described from Texas, S. (Trucifelis) fatalis (Leidy)?, of which the type consists of a single upper carnassial with a small portion of the maxillary attached. As this element is unrepre- sented in the present specimen, comparison was made with a fine skull of S. californicus from the Rancho La Brea asphalt, Cat. No. 10204, Y. P. M., and the com- parable ratios between that and Leidy’s type on the one hand, and the Dallas*specimen on the other, exhibit a close agreement, as the table of measurements shows. 2 Joseph Leidy, Jour. Acad. Nat. Sci., Phila. (2), 7, 366, pl. 28, figs. 10, 11, 1869. Am. Jour. Sci1.—FirTH SERIES, Vou. IT, No. 9.—SEpremMBER, 1921. 11 ; 162 R. 8S. Lull—Fauna of the Dallas Sand Pits. Measurements. S. fatalis Ratio S. californicus holotype No. 10204, after Leidy YP. ME. mm. mm. Carnassial Depth, infraorbital foramen to base of CrO WI siet: ands csc cet oe 31.75 0.793 40 Breadth ant.-post. diameter of CLOWN ps Rereklode eee he © ies 33.307 0.803 41.5 Thickness at position of inner but- EGOS Selassie ita he seks a ote See a siis 0.992 16 Depth of pmmcipal (cusp. se eee 19.05 0.846 22.5 Averare ratio: Sinan ee eee : 0.858 S. fatalis No. 1.52 S. M. U ahaa Length of parietal crest.......... 110 0.866 127 Breadth of braim-cases 2225 a... 4 93 1.022 91 Breadth of occiput at upper edge of foramen macnuml. 2] sco... 80 0.920 87 Height of occiput... eee a ee 65 0.890 73 Breadth across mastoids ......... 123 0.898 137 Breadth across occipital condyles . 60 0.87 69 Breadth at summit of occiput..... o0 80 AVERAGE atiO - O. P. Hay, Proc. U.S. Nat. Mus., 46, 270, 1913. R. S. Lull—Fauna of the Dallas Sand Pits. 171 relatively somewhat further forward. The infra-orbital foramen of the left side only is preserved, and this lies just above the anterior crescent of M' in seeming corre- spondence with that of C. huerfanensis; in both living genera the foramen lies a little further forward, above P*. The premaxillaries are broader and heavier in the Dallas specimen than in either of the recent genera. One apparent distinction between the Dallas form and the type of Camelops huerfanensis lies in the position of the canine, which ‘‘must have emerged immediately behind the incisor just as it does in the Bactrian camel’’ (Hay, p. 269). The Dallas specimen has an incisor- canine diastema of 16 mm. on the left and 18 mm. on the right. Measurements of Skull. i 2 3 Mn wikabio wm nmm. Ratio” /mm. Wer erimOVeriall tae. 2.) claw elavs seas « 500 1.08 540* Height of occiput from up. margin of POUAMEM WHA. WS ot ee c's fhe 2 68 1.00 68 Breadth of occiput on line through itera foramina. ise et tc). ey0 << 123 1.01— 124 1.12 110 Palate, width between P* .......... 35 115 40+ 0.80 50 Waidtheaerrontrot ME. Als oc. ua, 72 0.96 Goa BORT9 87 Length, premolar-molar ser., P*-M*.. 151 1.14 de weO 171 Teeth, front of P* to rear of M’.. 130 1.19 154. 1.16 152 ASL GIES AS) STe SUR ae a a 109 1.18 129 1.00 129 ee Meno inee. Ee fF... INS. Ow OR 20.5 1.02 21 1.12 18.8 12] SRC 1 ne eres (eee ee ee ee 24 1.14— eieopayel 09 25 I CINOMD Tye cer fi tice i ot YB So wiel's 34.5 1.07 37 0.96 38.5 Me lengthen i. oat PR RR eo 3, Stes te 0.97-— 42.5 0.88 48 Jy ETO ca ps at ei ie ee ee 22 25.04 62 - Length on grinding surface....... 43 at 52 1.15 45 TNETIC 18 Serenata Oo baie tee an ee 27 1.00 7 0.94— 28.5 Aversve rahosies.. Mi atk. 1.08 1.00 1— Camelus arabicus, Cat. No. 01552, Y. P. M. 2—Camelops huerfanensis dallasi, subsp, nov., Cat. No. 1.51, 8. M.U. 3 = Camelops huerfanensis, Cat. No. 7819, U.S. N. M., after Hay. * Estimated. t Restored. t In the Dallas specimen the teeth are much more worn, hence heights are much less, and as the teeth are worn, the length (ant.-post. diameter ) dimin- ishes (except i in the third premolar and the last molar), while the transverse diameter increases (Hay). This will account for most of the discrepancies. Cervical vertebra VI. —A single well preserved cervi- cal vertebra, No. 1.57, 8S. M. U., is present and appears to 172) R. S. Lull—Fauna of the Dallas Sand Pits. be of the same level as that of the skull. It is very remarkable for the huge development of the ventral branches of the transverse processes, which are deflected downward to such an extent that their axes are parallel. These processes are of less fore and aft extent than in the dromedary, but are much thicker and deeper. The centrum of the vertebra, on the other hand, is more Ce ‘ oo \ A ve tienes Fic. 5.—Cervical of (A) Camelus arabicus, Cat. No. 01552, Y.P.M.; and (B) Comers huerfanensis dallasi, subsp. nov. Paratype, Cat. No. 1.57, S. M x% slender in the fossil, which gives the forward articular surface especially a somewhat less area. The planes of the two centrum faces are not parallel, but indicate a marked upward flexion of the neck, more so than in the equivalent element of the dromedary (see fig. 5). Dorsal vertebra.—A first dorsal, Cat. No. 1.60, S. M. U., perfect except for the spinous process, is also present. It shows signs of stream transportation (and doubtless comes from the lower level). It approximates the equiv- alent bone of the dromedary (01552, Y. P. M.) in size, but differs in having a somewhat heavier neural arch and shorter, broader centrum with a flatter ventral aspect. Measurements of Vertebre. Camelus Camelops arabicus huerfanensis No. 01552, dallasi WE Me No. 1.51, 8. M. C. mm. Ratio mm. Cervical VI: length of centrum -)5..2-)- 142 1.03 146 R. 8S. Lull—Fauna of the Dallas Sand Pits. 173. Length over zygapophyses.. 175 0.91 160 Height, prezygapophyses to inf. transverse processes.. 121* 1.43 176 Hlerenorover aly 3.08. 1A0% 1.35 2307 BAGVIETAGE PALIO sige yei a sss 6 es 0 faite) | | No. 1.60, 8. M. U... Dorsal I: mm. mm. Length of centrum......... 92 0.86 79 Post. depth of centrum .... 54 0.94 52 LEO RSG ACAI Leander nan 80 1.05 84. NWwadthinover aly... e. oc... 120 1.08 130 PAVE ACE PATIO NG seein os owe 0.98 * Not completely ossified. t Estimated. Ulno-radws.—There is an admirably preserved right. ulno-radius, No. 1.58, S. M. U., which compares closely with that of the dromedary (No. 01552, Y. P. M.). The- ulna shows the same degree of reduction, but the bone asa whole is slightly shorter, wider, and flatter at mid-length, and shows a less degree of curvature. Measurements. Camelops Camelus huerfanensis - arabicus dallast No. 01552 No. 1.58 Ve Pe Mi. Ratio S. M. U. mm. mm, liemethwovervall:. 2)... 4%. ts. 99D 0.99 990 emethol TAGIUS apc... « 490 0.98 480: Wacdtia, mid-shatt ..0..2 4... 57 1.18 67 Thickness, mid-shaft ....... 41.5 0.94 39 Wadih: prox: end ...2..... 95 0.98 93m Wadi distwend.:s . aes << s. 94.5 0.95 90 PNVCLAGE GAUIO: ... sca ve 1.00 * Abraded. Metatarsal—aA right metatarsal, No. 1.56, 8. M. U.,. agreeing approximately in size with that of the drome- dary (No. 01552), is present. It is not preserved through- out its entire length, having lost the distal end, but gives the impression of greater relative weight than in the recent form, and the longitudinal ridges on the posterior aspect are more nearly equal in prominence. It also. seems somewhat straighter when seen in profile. 174 R. S. Lull—Fauna of the Dallas Sand Pits. Measurements. a Camelops Camelus huerfanensis arabicus dallasi No. 01552 No. 1.59 V2 PM: Ratio S. M. U. mm. mm. Ienotheofshatt <25 20. secs Sail 1.05 joa Width, prox. cend” 2 37 ee ee 62 1.08 67 Width, mid-shatt .....288: 34.5 1.14 ao3 Thickness, mid-shaft ....... om 1.08 40 Average ratioyit si. 22 eee 1.09 Summary.—This Dallas form resembles Camelops huerfanensis in size and general proportions, in so far as comparison may be made, but differs in the details of the occiput, the presence of diastemata between I? and the canines, and in the larger size of the metastyle of M?. These characters, if they are not merely sexual, are at least of subspecific rank. The name dallasi is given therefore to the form based upon the skull as holotype. Camel, gen. et sp. mdet. No. 1.63, S. M. U., an almost perfect rear cannon-bone, represents a considerably smaller camel than C. huer- fanensis, but I can not as yet identify it. : M easurements. No. 1.63 No. 1.59 S. M. U. Ratio S. M. U. mm. mm, Meneth 9 Olen 2o ee rees 275 0.77 Sais Wadth,prox.end = Ses 62 0.92 67 Wadth,-muad2shant @a.20 sae 36.5% 0.92 39.5 Thickness, mid-shaft ....... 34T 0.85 40 Average 1ati0*. 23 ceeeeee 0.86 * Estimated. | + Abraded. The ratios indicate a very short-footed camel for its bulk. R. 8S. Lull—Fauna of the Dallas Sand Pigs, 1S Equus cf. fraternus Leidy. Cat. No. 1.61, S. M. U:, a cannon-bone (mep IIT), and No. 1.56, the distal halves of two right humeri, are all the horse material in the present collection. They repre- sent a small horse or horses near to if not identical with Equus fraternus Leidy. I have compared them with the skeleton of a recent pony in the museum of the Yale Zoo- _ logical Laboratory, with the following results: No. 1.61 E. caballus Ratio S. M. U. mm. mm, Molar 1, fore and aft diameter.. 22 1.07 ipa fore Cannon-pone, length ........... 207 1.06 220 isread@ul. LOX. CNM... sy... fs 46 OGL 42 Breach, mid-shalt of... 3.55. 44 0.88 40 isreadia, dist. end’ |. os Pats ht, DO 1.09 31 Humerus, breadth, mid-shaft ... 30 1.23 37 Breaden dist: emde is .20 5S. 70 1.10 17 Ant.-post. diameter, dist.end.. 66 All 80 Average ratio ........ Vises ele 1.07 * Taken from EF. fraternus, No. 9217, U. S. N. M. See Gidley, Bull. Amer. Mus. Hist., vol. 14, 113, 1901. The ratios of teeth and cannon-bone are very close, the apparent discrepancies being due in part to erosion of the present fossil. The humeri, on the other hand, seem to pertain to slightly heavier horses, but the range of individual variation within the species might account for the difference in size. Elephas columbi Falconer. The proboscidean material from the Lagow sand pit now in my hands includes a tooth, No. 1.54, 8S. M. U., and a cervical vertebra, No. 1.55, 8.M.U. The tooth is unquestionably from the upper level, having all the char- acters, color, preservation, etc., of the Camelops skull already described. The matrix on the cervical differs, however, resembling that of the camel ulno-radius. The tooth appears to be a left upper second deciduous molar, and has four and a half elliptical enamel ridges, having a single plate intercalated between the two for- 176 R. S. Lull—Fauna of the Dallas Sand Pits. ward complete ellipses, and space beyond for another ridge of which the enamel is apparently worn away. The worn surface of the crown measures 78 mm. (about 3.5 inches) in length, as preserved, by 70 mm. in width. Five and one half folds in 3.5 inches is about equivalent to sixteen in 10 inches. Lucas gives the following: Elephas imperator, twelve in 10 inches; E. columbi, eighteen; E. primigenius, twenty-four. Our specimen comes nearest to columbi. . The enamel is crenulated and in its present condition there is a fair amount of sur- rounding cement. The tooth was borne on at least two transverse roots. The cervical represents the seventh cervical of a mature elephant, presumably EF. columbi, although this same pit has yielded, apparently from its lower level, what I have identified as LH. amperator. This is the Yale specimen, Cat. No. 10028, already referred to. Verifica- tion of the specific identity is at present impossible, as the specimen is in inaccessible storage. The centrum is approximately amphiplatyan, very short in its antero- posterior diameter, with the faces converging above, neural arch light, with a slender spinous process, and the prezygapophyses a little above the level of the postzyga- pophyses. Small tubercular rib facets are present just below and slightly external to the postzygapophyses, that on the right side being the lower. A trace of the capitular facet is also present on the right side well down toward the base of the centrum. Measurements. mm. Centrum, ant.-post. diameter at center ...... 41 Width Darwin = Delage = De Vries = Durkheim = Eddington = Edgeworth = Emery = Enriques = Fabry - Findlay - Fisher = Fowler = = Golgi = Gregory = Harper = Hartog = Heiberg - Hinks- % Hopkins-Inigues-Innes-Janet-Kaptein-Kaye-Kidd-Langevin- Lebedew-Lloyd Morgan= 3 Lodge = Loisy - Lorentz - Loria =Lowell - MacBride - Meillet =-Moret=Muir=Peano =Picard = Poincare = Puiseux = Rabaud = Rey Pastor = Righi-Rignano-Russell-Rutherford-Sagnac= - Sarton- Schiaparelli- Scott = See = Sherrington = Soddy = Starling = Svedberg =- Thomson = am ‘Thorndike-Turner -Volterra-Webb -Weiss = Zeeman-Zeuthen and more than a handred others. 3 **SCIENTIA’’ Poblighes” its articles in the ianeuaee of its authors, and joins to the = principal text a supplement containing the French translations of all the articles that are not in French. (Write for a Specimen Number to the General Secretary of - “ _'Seientia”, Milan. ) Annual subscription : 40 sh., or 10 dollars post free. : ~ Office : - 43 Foro Bonaparte, Milan, Tale Poblishers WILLIAMS & NORGATE- Ligedins FELIX ALCAN - Paris oe ane NICOLA ZANICHELLI-Bologna ; WILLIAMS & ; WILKINS CO-Baltimore.~ : Arr. xX. Some Mechanical - ae cone with Earth’s Field of. Force ; a Arr. ‘XL —Fauha of the Dallas Sand Pits ; by cs oe 5 C & Z * e ae | Apr. XII. —Direa ee dye ae morphological s T. Houm.. indy 3 ‘Ant: XII. aay Men els from British Columbia 5 ; aN: BERRY. . fan bp Or ac rete! rae ; if : F 4 ‘ .% ; 7 : i ae | A 2 27 ; . Lf) THE ¥ ; oe i . fi ~ s 7 RAL OF SCIENCE, "Exton: : EDWARD S. DANA. tetas = ASSOCIATE EDITORS ~ | Poorssons WILLIAM M. DAVIS AND RE GINALD A. DALY, en = OF. Camsripan, Prorsssons HORACE a WELLS, CHARLES SCHUCHERT, HERBERT EB. GREGORY, WESLEY R..COE anp ; _ FREDERICK K. BEACH, or New HAVEN, oe peace EDWARD W.. BERRY, OF: Baurrmore, eee, Li -RANSOME. AND WILLIAM BOWIE, re nara “OF WASHINGTON. i FIFTH SERIES OL. ‘TL-[WHOLE. NUMBE 1K, COIN. \ No. 10 OCTOBER, 1921. oS ome oe | NEW HAVEN, CONNECTICUT.. ee og Al me ‘Six, donee “per year, in Tacos 3 $6. 40 to countries in the ) to Single numbers 50 cents} No, 271, one dollar. | at the Post Ofiee, at New eas , Conn. ’ lea alts the Act + = * = ‘iat ana “HanpBoox FOR FIELD Gane as “Third Edition, Thoroughly Revised - and ‘Enlarged pee > te a : = By the late C. WILLARD HAYES, ‘formerly Chief Geologist, Sie Geological Survey. Revised and 7 by SIDNEY fees. aii Uv. S. Geological Survey. _ ‘This new edition, which has ieee Seoigkt Pit 1 up ‘to ache ote oe | ae ~-methods of pr ocedure to be followed by geologists when working in the field. he Real, serviceable data are given ina practical, convenient way, based on 1 both — : authors’ wide range of | lose aE in n geologic field. work in the rated, States and abroad. ee : = += 166 pages. A455 Ge 654 inches: 20 irises: 31 plates. Eee = Flexible Binding. $2. 50 postpaid ry ve ~ TextB00x OF fae” eee = Part I, PHYSICAL GEOLOGY es ig Pee S By the late LOUIS V. PIRSSON, formerly Professor of. Physical Geology, Sheffield Scientifie School, Yale University. : é 5 470s Pages. 6 by 9. 811 figures, 1 folding colored map. Cloth, $3.00 7 Soe ‘Part I, “HISTORICAL GEOLOGY , aS SS ee = By CHARLES SCHUCHERT,, _ Professor of. Paleontology in Yale University. 622 pages.” 6 by 9. 211 fgures, 40 cae : 1 folding. colored map. : ‘Cloth, $3.50 postpaid. ~ 2 iS Combined Edition — - 1051 - pages, 6 by 9. gures: 2 olting colored 3 We § ~ map. Cloth, $5.50 Piles od Bae A) es ELEMENTS 0 OF ENGINEERING CeoLocy By H. RIES, Ph.D., Professor of Geology, Cornell Universtiy. anes 4 THOMAS L. WATSON, Ph.D., Professor of sa Be Daas Virginia. - 7 : = 365 pages. 53 by 84. “959 figures. - Clot, $3.75 postpaid. ; Send T sok x ‘for copies for cee es fe JOHN WILEY & SONS, tees = ~ 432 Fourth Avenue, New York © = ee - London: Chapman & Hall, Ltd. - Montreal, Quebec: Senout Syoleine Cgenanys —- -agsi0- 2 ae Ss OS AMERICAN JOURNAL OF 5 [FIFTH SERIES.] +0 Arr. XIV.—Further Remarks on the Evolution of Geologic Clumates; by F. H. Knowtton.1 In the April, 1921 number of this Journal there are two articles critical of my recent paper on ‘‘ Evolution of Geologic Climates.’’ These are: ‘‘Paleobotany and the earth’s early history,’’ by A. P. Coleman, and ‘‘ Evo- lution of geologic climates,’’ by Charles Schuchert. These articles seem to call for brief consideration. The thesis of my paper (p. 901) reads in part as follows: ‘*Relative uniformity, mildness, and comparative equability of climate, accompanied by high humidity, have prevailed over the sreater part of the earth, extending to, or into, polar circles, dur- ing the greater part of geologic time—sinee, at least, the Middle Paleozoic. This is the regular, the ordinary, the normal condition.’’ That the truth of this statement is very generally recognized is shown even by the admission of both Pro- fessor Coleman and Professor Schuchert. Thus the former says: ‘His [Knowlton’s] account of the vegetation of the past con- firms and heightens the impression left by paleozoology that during the greater part of the world’s history temperatures have been genial even in the far north and far south where frigid climates now reign.”’ And Schuchert says: ‘“Any paleontologist who is familiar with the climatic aspects * Published with the permission of the Director of the U. S. Geological Survey. Am. Jour. Sct.—FirtH Serises, Vow. II, No. 10.—Octoser, 1921. 13 188 F. H. Knowlton—Evolution of Geologic Climates. of fossils will probably have to agree with Knowlton that the biotic evidence, and chiefly that of the floras, does in general bear out his conclusion that ‘climatic zoning such as we have had since the beginning of the Pleistocene did not obtain in the geologic ages prior to the Pleistocene.’ ”’ Let us take first the question of so-called ‘‘ice ages.‘‘ I have freely admitted that there are evidences of refri- geration at a dozen or more points in the geologic column between Huronian and Kocene, but I have questioned whether more than three of them as at present known are entitled to be called ‘‘ice ages.‘‘ Coleman says: ‘‘The presence of great ice sheets in Australia, South Africa, South America, and India, as admitted by Knowlton himself, is fatal to the theory he advocates, and no suggestion that the period of cold was short affects the conclusion.’’ If it could be proved that the glaciation on these conti- nents took place with earth temperatures under solar control as Professor Coleman appears to believe, it would indeed be fatal to the theory I have advocated, but this has not yet been demonstrated. Glaciation in or adjacent to the tropics at or near sea-level, as attested by inter- bedded marine deposits, is to my mind impossible under the rays of a vertical sun! The Permo-Carboniferous glaciation is one of the unexplained mysteries of geology, someone has said, and — with the assumption of solar control this is undoubtedly true, but with the predication of dual heat supply it can be and is explainable. The manner in which this principle is applied is ex- plained at length in my paper and need not be here repeated. It is an explanation that has at least the merit of explaining certain phenomena that are matters of common knowledge and observation that obtrude in studies of geologicclimates. It will be noted that nowhere in my paper has it been denied that there are repeated evidences of refrigeration, and it is more than likely that others may be discovered, but my main contention is that, with the exception of possibly three (Huronian, Permo- Carboniferous, Pleistocene), there is to my mind no adequate evidence available that they were more than local, and without widespread effect on temperatures, distribution of life, ete. . This linking up of isolated localities all over the world without adequate age-deter- mining data seems to me to be unwarranted. F. H. Knowlton—Evolution of Geologic Clmates. 189 The question of oceanic temperatures may be consid- ered. On this point Schuchert says: ‘“But what Knowlton actually holds is... that the tem- perature of the oceans was everywhere the same without ‘wide- spread effect on the distribution of life.’ ”’ A ‘‘eareful reading’’ of my paper, such as Schuchert says he gave it, discloses that what I actually said was as follows: ‘“It now seems to be settled beyond serious question that the waters of the early oceans were warm—in fact that they were not permanently cooled as they are now until the approach of the Pleistocene. This does not necessarily mean that there may not have been fluctuation in their temperature from time to time, for there doubtless was; but, taken by and large, the oceans were warm from the equator to the poles. On this point Ulrich says: ‘Taking the geologic marine record, as preserved in the fossil- iferous rocks from the Cambrian to the Tertiary, it suggests equable, mild, almost subtropical climates over the whole North- ern Hemisphere in all the ages represented.’ ‘*Ulrich also adds that there is undoubted evidence, notably in the early Cambrian, and early in the Pennsylvanian, when ‘frigid conditions occurred, at least locally.’ This is the very crux of the matter, for it seems clear that while there are undoubted evidences of glaciation, they were, at least for the most part, so very local in their effect that they seem to have made very little impress on the temperature of the oceans, and hence on the continuity and distribution of marine life.’’ Professor Schuchert devotes several paragraphs to the testimony of marine fossils in reflecting temperature changes. Certain groups of animals were common in the far north ‘‘and even in arctic water’’ during the Silurian, Devonian, Pennsylvanian, and Jurassic, while at other times they were greatly restricted or absent from these regions. ‘These, he thinks, ‘‘can only mean temper- ature influences, and that the northern waters were frequently under 65° F.”’ ‘‘On the other hand,’’ he adds, ‘‘when the lands are largest and the marine faunas localized in small sea-ways and not widely accessible to the paleontologist, where are the cosmopolitan faunas and the larger forms?”’’, ete. This seems a rather futile question to ask, for if the faunas were confined to the small water-ways when the continents were emergent, there was little for them to do but back off into the deeper oceanic waters, where the 190 F. H. Knowlton—Evolution of Geologic Climates. temperature changes but slowly, there to await the return of more favorable conditions. Schuchert appears to rec- ognize the potency of physical causes other than temper- ature in delimiting these stress-faunas, but adds: ‘‘yet the chief deterrent seemingly was the lack of proper warmth.’’ But this appears to be opinion unsupported by corroborating facts, at least in this paper. The testimony of a number of well-known invertebrate paleontologists may be cited on this point: Thus, Doctor Ulrich has already been quoted as saying that the geologic marine record, from the Cambrian to the Tertiary, ‘‘suggests equable, mild, almost subtropical climates over the whole Northern Hemisphere in all the ages represented.’’ There is evidence, Ulrich adds, of times when ‘‘frigid conditions occurred at least locally,’’ but he makes no mention of any zonal disposition of temperatures. Dr. John M. Clarke writes that while ‘‘there is of course plenty of evidence of cold weather periods and also of local cold throughout Paleozoic history, I can not say that such determinations are, in any single particular within my knowledge, dependent upon the fossils of the rocks; nor can I say that the obvious evidences of recur- rent land glaciation are connected in any way or sup- ported by any facts deducible from coexistent faunas and floras.”’ Dr. James Perrin Smith, after discussing the range of certain Triassic limestone with thick coral reefs, inter- prets the evidence as indicating ‘‘a nearly uniform distribution of warm water over a great part of the globe’’ during Triassic time. Dr. T. W. Stanton permits me to say that in his extensive studies on the distribution of Jurassic faunas from Texas to Alaska he has failed to find any indication of climatic zones, and Burckhardt has had a similar experience in his studies of the Jurassic faunas of northern South America and Mexico, where he found a striking mixture of types that should appertain to two or more of the so- called climatic zones as interpreted by Neumayr. If it is urged that some of the above examples relate to distribution in the middle portion of systems, examples are not wanting of beds closing or initiating systems that are likewise widespread and without evidence of climatic zoning. ‘Thus Doctor Ulrich directs my attention to the F. H. Knowlton—Evolution of Geologic Climates. 191 Richmond group, that ranges from Baffinland, Alaska, and Baltic Russia south as far as Texas and India. The earliest Niagaran had nearly the same wide-flung distribution. The earliest Devonian Helderberg group, as well as the earliest Mississippian black shale beds, were likewise widespread and without temperature zones. As near as I am able to interpret certain recent remarks of G. R. Wieland,? he appears to hold that much of the paleobotanical data relied upon to interpret geo- logic climate was based on studies of lowland floras, whereas, when the highland floras are studied, if they are ever available, quite another story may be told. This is easily answered. Interpretations have been based on floras that are actually known and not on what may yet be discovered. To return again to some of the objections raised by Professor Coleman. In discussing seasonal changes he says that after admitting the presence of growth rings in trees in the Pennsylvanian, Permian, Jurassic, Cre- taceous, etc., I do ‘‘not explain how this can be reconciled with the uniform and steady supply of heat from the earth’s interior under the assumed screen of clouds.’’ I do not recall that I ever stated that the supply of earth heat was ‘‘uniform and steady,’’ for I entertain no such view. My whole paper is predicated on a dual heat supply, that from the earth itself and that from the sun. The earth heat undoubtedly fluctuated from time to time as evidenced by vulcanism, to use no other example. When earth heat was at a maximum the cloud envelope was most complete and the sun shut out, but when earth heat diminished evaporation and the cloud spheroid also diminished. Ihave quoted on this point as follows in my paper (p. 541): ‘* As the heat carried up from the earth’s surface was more and more lost by radiation into space from the exterior cloud-surface, the isothermal shells would gradually descend, and the tempera- ture of falling rains would become lower, so as under favorable conditions to fall as snow. It is clear that snow-fall might occur at any period of earth’s evolution on high mountain ranges or plateaus, and there the accumulations of snow might at any period have formed nevees and glaciers with their well known effects.’’ “Science, n. s., vol. 53, p. 437. 192 F. H. Knowlton—Evolution of Geologic Clumates. Under this postulate cooled, if not glaciated, areas could have been developed at any time and place where the conditions were favorable, and these could easily have been reflected in the growth-rings. But again it seems necessary to call attention to the fact that growth-rings are not dependent on changes in temperature, but are produced with equal facility by changes in the supply of moisture. The so-called seasonal banding of Pleistocene clays is an attractive study, and it seems to many to have been > demonstrated by De Geer and others with reasonable certainty as the result of seasonable changes in sedimen- tation. It must be admitted that the resemblance is striking between these Pleistocene clays and certain banded shales and slates of earlier geologic ages, but on consultation with a number of physical geologists it appears that not all are as yet prepared to accept it at its assumed face value. They point out that we still - know so little of the physical conditions surrounding the sedimentation in which these bandings occur that it may be hazardous to attempt to connect them with seasonal fluctuations, especially when unaccompanied by evidence of glacial activities as many undoubtedly are. These ‘‘orowth-rings’’ of the rocks as they have been called are obviously dependent on a periodic supply of moisture, but does it necessarily follow that this fluctuation was seasonal? A circumstance recently reported to me by Prof. A. F. Foerste of Dayton, Ohio, may be of interest. All will recall the disastrous flood that swept Ohio some years ago. This flood was three days rising and four days receding. When it was possible to enter the town Professor Foerste © found the floor of his laboratory covered with a layer of fine mud some six inches thick. This mud was distinctly stratified, there being not less than twenty-five distinct layers that must have been formed within less than a week. I shall have to leave this so-called seasonal banding an open question. Under evidence of aridity Professor Coleman says: ‘“To dispute the formation of salt and gypsum beds by evapora- tion in times of dry heat without suggesting any other mode of forming such deposits is surely unwarranted.’’ Let us consider the formation of gypsum, pure deposits F. H. Knowlton—Evolution of Geologic Climates. 198 of which 30 to 60 or more feet in thickness are not uncom- mon. R. W. Stone® of the U. S. Geological Survey has recently reviewed the subject and, after pointing out that calcium sulphate constitutes only about 3.6 per cent. of the 3.5 per cent. of mineral salts held in solution in sea water, Says: ‘“With these facts in mind, it is difficult to account for the great thickness of some gypsum beds. The quantity of water of nor- mal salinity which would have to be evaporated to make a gypsum deposit 30 or 60 feet or more thick is so great that no known ocean basin would hold it. From 1,000 feet of normal sea water about 0.7 foot of gypsum would be precipitated before the point of saturation for sodium chloride would be reached; to precipitate 30 feet of gypsum would require about 43,000 feet of water.’’ The explanation offered then is the evaporation of sea water in an inclosed basin which is shut off by a low barrier from continuous access to the sea but which is © continually replenished by periodic incursions of the sea. Can Professor Coleman visualize the physical setting necessary to account for gypsum deposits in all parts of the world at all geologic horizons, and so nicely adjusted as to admit just the right amount of water at just the right times and just the right degree of concen- tration to keep the deposition a continuous and appa- rently uninterrupted process? Should not the layers of gypsum, if accumulated under these conditions, be of fairly uniform thickness and widely extended? It is well known, however, that gypsum deposits thicken and thin laterally within very short distances in a very discon- certing manner. Why are gypsum deposits unfossilifer- ous? . Because the water had already reached such a degree of concentration as to be unfavorable to life, we are told, yet is it not rather remarkable that during the hundred of times the impounded water must have been replenished from the adjacent sea that no marine life or impurities of one kind or another found entrance? Stone states that 80 per cent of this impounded sea water must be evaporated before the deposition of gypsum begins, and seemingly every fresh incursion -of sea water would so dilute it as automatically to stop the deposition of gypsum until the earlier deposited solids had been thrown down. The beds of gypsum should therefore be inter- * Stone, R. W., Gypsum deposits of the United States, U. S. Geo. Survey, Bull. 697, pp. 22-26, 1920. 194 F. H. Knowlton—Evolution of Geologic Climates. rupted by layers of other solids, which it seems is ordi- narily not the case. The deposition of a bed of pure gypsum from the evaporation of a single filling of this postulated inclosed basin is understandable, but when we must account for beds 30 to 60 feet thick, calling for the evaporation of a body of water from 8 to 15 miles deep, the proposition becomes top-heavy. A further compli- cation also arises when it is recalled that many of the deposits containing gypsum are obviously continental deposits. Of course deposition by evaporation from impounded water is not the only way in which gypsum may be formed. Thus, some deposits are now explained as deposition from solution in ground water and others as deposits produced by alteration, by action of sulphuric acid on calcium ear- bonate. Bedded limestone may be changed to bedded gypsum by contact with sulphuric acid derived from ground water from pyritic shales. The gypsum deposits in the Silurian of New York are thus explained. In an abstract of a paper on ‘‘Some conclusions in regard to the origin of gypsum,’’ just published, F. A. Wilder‘ says: ‘*While admitting that this [salt-pan] theory best explains some gypsum deposits it seems probable that many important bodies of gypsum owe their origin to other causes and conditions. Present day gypsum deposits are, for the most part, afflo- rescent deposits, periodic lake deposits, spring deposits, and deposits due to the alteration of carbonate to sulphate. There is reason to believe that many important gypsum deposits of earlier periods owe their origin to similar causes.’’ Professor Coleman says that to dispute the formation of gypsum beds ‘‘by evaporation in times of dry heat’’ is unwarranted. As to the matter of dry heat, I have been under the impression that evaporation depended on the relative humidity and pressure of the atmosphere, that is to say, if the air contains less moisture than it is capable of holding there will be evaporation quite irrespective of the temperature. From the above discussion of the processes by which oypsum may be deposited and the difficulties that seem to beset its accumulation by the evaporation of impounded sea water, it appears to me that the blanket statement * Wilder, F. A., Geol. Soc. Am., Bull., vol. 32, p. 67, 1921. F. H. Knowlton—Evolution of Geologic Climates. 195 that deposits of gypsum necessarily imply aridity is ‘‘surely unwarranted.’’ That gypsum may sometimes be precipitated from impounded sea water is undoubtedly true, but that all or even a very considerable part is so formed is not proved, and, I may add, that to my mind _ itis not provable. As a supposed sure indication of aridity the presence of red beds furnish another case in point. It now seems to be acknowledged that the formation of red rocks (except when derived from rocks originally red) is not now known to be going on under desert conditions at the present time, and hence there is little reason to suppose that they were so deposited in the past. The presence of so-called sun cracks seems also a ques- tionable indicator for aridity. They might better be called shrinkage cracks, for they are developed whenever and wherever mud dries out, whether the sun is shining on it or not. Professor Coleman ‘‘finds it difficult to believe in a warmly humid world enveloped in rain clouds that never parted to let in the sun until the Pleistocene.”’ Again I must call attention to the fact that I have nowhere stated that the sun never shone through the cloud envelope, but rather that it did not gain permanent control of earth temperatures until or approaching Pleistocene time. Both Professor Coleman and Professor Schuchert appear to have overlooked or perhaps failed to appre- ciate one of the principal objects I had in mind in writing the paper on geologic climates, namely, the search for the explanation of certain of the fundamental principles that must have operated in determining and delimiting the climates of the past. For example, has the sun dominated earth tempera- tures throughout all geologic time as it is acknowledged to have done during and since Pleistocene time? If the sun causes a zonal disposition of temperatures on the earth’s surface, what caused or permitted the non- zonal disposition that all agree to have obtained for at least vast stretches of time when climates were undoubt- edly equable over the whole earth? What was the source or sources of heat that warmed the early oceans? 196. ol on a of Geologic Climates. Is the Sésiaiette of a dual heat supply a logical and legitimate proposition? These and other problems of similar import are left untouched. Constructive criticism is always helpful; destructive criticism is less so. I asked for bread but thus far have received little but striated pebbles. Troxell—Diceratherwm and the Diceratheres. 197 Arr. XV.—A Study of Diceratherwm and the Dicera- theres;: by EKywarp L. T’RoxEtu. [Contributions from the Othniel Charles Marsh Publication Fund, Peabody Museum, Yale University, New Haven, Conn. | TABLE OF CONTENTS. Introduction. The true diceratheres. Dicerathertum Marsh. Diceratherium lobatum, sp. nov. Diceratherium cuspidatum, sp. nov. The diceratheres of the Great Plains. Menoceras cooki (Peterson), gen. nov. Metacenopus egregius (Cook). Summary. INTRODUCTION. At present there are but two species of Diceratherwum, » D. armatum and D. annectens, which are accepted without ~ reservation by students of paleontology; yet species from two continents have been referred to the genus, as well as all specimens ‘from the John Day region of Oregon and those from the Lower Miocene of the Great Plains. Our inability to classify harmoniously all the two- horned rhinoceroses under this genus does not tend to lessen its importance nor its distinction, and although there is a wide variation in John Day rhinoceroses, it is necessary to put them together into one group and at the same time separate that group from all others. Following is a list of the Oregon species of the true Diceratherium: Diceratherium hespervum (Leidy) 1865. Inadequate. Figured heautotype, Cat. No. 10259, Y.P.M. Diceratherium pacificum (Leidy) 1871. Inadequate. Figured heautotype, Cat. No. 10287, Y.P.M. Diceratherium annectens (Marsh) 1873. Holotype, Cat. Noe W001. YPM. | Diceratherwum armatum (Marsh) 1875. Genoholotype. Holotype, Cat. No. 10003, Y.P.M. 1 This is the last of the series of four papers on the American rhinoceroses. Three other parts appeared in this Journal for July, 1921. It is a pleasure to state that all of the drawings in these four papers were made by Rudolph Weber, whose work is so well known to scientists everywhere, 198 Troxell—Diceratherium and the Diceratheres. Diceratherwum nanum (Marsh) 1875. Holotype, Cat. No. 10004, Y.P.M. Diceratherwm truquianum (Cope) 1879. Holotype, A.M.N.H. (Cope Coll.), Cat. No. 7333. ?Dicerathertum oregonense (Marsh) 1873. Incerte sedis. Holotype, Cat. No. 10002, Y.P.M. Diceratherium lobatum, sp. nov. Holotype, Cat. No. 12487, -Y¥.P AM. Wie: Diceratherwm cuspidatum, sp. nov. Holotype, Cat. No. 12007, Yoav ie ae THE TRUE DICERATHERES. Diceratherium Marsh. The genoholotype, D. armatum, based on a large skull (Cat. No. 10003, Y.P.M., fig. 5) from the middle John Day beds of Oregon, has unusually simple teeth and enlarged broad nasals with rugosities not rounded, but elongated antero-posteriorly, separated and directed outward. Its size and the simple, primitive teeth make us think that the living conditions were not severe, that there was an abundance of nourishing food, and a moist chmate. The molars resemble those of Metamynodon. Diceratherine species from the Great Plains are here separated from Diceratheriwwm Marsh and put under separate generic groups: Metacenopus Cook and Meno- - CETaS, Fen. NOV. The species with simpler teeth, of larger size but with more subdued nasal eminences, belong with the genus Metacenopus, genoholotype M. egregius Cook. The smaller animals from the Agate Spring quarry, of slightly later age, with teeth more progressive in their subhypsodonty and in the development of additional folds of enamel, with horn rugosities even more prominent than in Diceratherwm, are grouped under Menoceras nobis, the genoholotype of which, D. cooki Peterson, is defined later. | Diceratherium armatum Marsh.—The following points may serve in part to define this species: (1) males with well developed, widely separated, oval rugosities on the nasals in maturity; (2) moderate deepening of sinuses and pits of teeth, or increase in height of ridges, reaching an extreme in later rhinoceroses (?D. oregon- Troxell—Diceratherium and the Dieerathends: 199 ense); (3) cingula broken on the molars, weak on the tetartocones, with a tendency toward elimination; (4) development of minute folds into a crochet, but virtual absence of a true crista; (5) moderate grooves on the protoloph of molars, separating the protocones from the protoconules, absent on premolars; (6) incisors and canines lost from premaxillary, except first and possibly second incisor; (7) milk dentition rather complex; (8) in size one of the largest rhinoceroses of the time; (9) geological age, middle John Day, corresponding to the Upper Oligocene or Lower Miocene of the Great Plains. Fic. 1.—Premaxillaries showing the development of incisors in various species of Diceratherium in the Yale collections. All shown from the left outer side. 1/3. A, D. armatum. Cat. No. 10005. Second incisor unknown and bone restored in outline. B, D. armatum. Cat. No. 11068. Two moderately large incisors present. C, D. lobatum, sp. nov. Holotype. Cat. No. 12487. Lobate character of incisors and relatively large size of second one are unusual features. See figure 6 and the text description. D, D. nanum. Cat. No. 11184. Drawn reversed. Note persistent small second incisor. In this old individual the prominent horn rugosities are wide spreading. EL, D. nanum. Holotype. Cat. No. 10004. See figure 2 and the text description. No second incisor present. F, D. annectens. Holotype. Cat. No. 10001. See the text description following, and also figure 3. G, D. annectens. Cat. No. 12019. A young specimen with premolars almost exactly like those of the holotype (fig. 3) but slightly smaller. Nasals broad but no prominences have developed. Dicerathertum annectens (Marsh) is a smaller species of rhinoceros, also from Oregon; it was named by Marsh from a specimen (Cat. No. 10001, Y.P.M.) consisting 200 Troxell—Diceratherwm and the Diceratheres. of the four upper premolars, the large upper incisor (see fig. 1 F’), and the distal end of the tibia. The premolars (fig. 3) measure in length three fourths those of D. armatum, the incisor less than two thirds. The species differs so markedly from the type species of the genus that it might justly be put in some other group: (1) the crochet is almost lacking, possibly due to wear, the crista being much more distinct; (2) the cingula are entirely obsolete on the inner side of the deuterocone, but are strong around the tetartocone; and (3) the size is much smaller. In certain features this species is more progressive: the deeper pits and sinuses, the criste, and the grooves marking off more distinctly the deuterocone in P?+. It has a close similarity to Jlenoceras cooki in its size, broken cingula, and the general form of the cross lophs; but the differences, especially the foldings of enamel, are greater and more fundamental. Peterson (1920) is justified in putting Diceratherium nanum Marsh in a minor taxonomic position, because the type is so incomplete; there is, however, a difference from D. annectens of one fifth in the size of the incisors, the only parts duplicated. The worn teeth and broken skull of the holotype of D. nanum are nevertheless of value in showing the reduction of the incisors: to the formula, I4, and in showing the long diastema between the incisors and premolars, and the true D. armatum type of horn cores. (See fig. 2.) ne TARE SRE SS NSA : Ses \\ \ \\ A WIA WESTER NENW NQQ SNS £ SS eek a \ SS Fig. 2.—A comparison of the horn rugosities in (4) Menoceras cookt (Peterson), gen. nov., Cat. No. 10273, Y. P. M., where they are rounded knobs; and (B) Diceratherium nanuwm Marsh, holotype, Cat. No. 10004, Y. P.'M., showing the broad nasals with elongated narrow ridges typical of all true diceratheres. 1/3. . Troxell—Diceratherium and the Diceratheres. 201 Of the six species of rhinoceros named from the John Day beds, D. hespertum (Leidy), D. pacificum (Leidy), D. truquianum (Cope), D. nanum Marsh, D. annectens (Marsh), and D. armatum Marsh, we agree with Peterson that only the last two constitute valid species, although some of the others may give valuable hints on the fauna. Fig. 3.—Diceratherium annectens (Marsh). Holotype. Cat. No. 10001, Y. P. M. Premolar teeth with simple parallel lophs. » 1/3. Fig. 4. Fig. 4.—Restoration of Rhinoceros (Diceratherium) oregonensis Marsh. Holotype. Cat. No. 10002, Y. P. M. Probably the fourth premolar of an undetermined genus from the Mascall formation of the John Day Valley, Ores. 1/3. Rhinoceros (?Diceratherwm) oregonensis Marsh, known only by the fragment of a tooth (Cat. No. 10002, Y.P.M., fig. 4), shows the presence of a large, much advanced genus in the Mascall beds of Oregon, compar- able to the Miocene or Pliocene rhinoceroses elsewhere. Fig. 5.—Diceratherium armatum Marsh. Holotype. Cat. No. 10003, Y. P. M. Crown view of molars and premolars. Note simplicity of the teeth, molar-like form of premolars, and large size. x 1/3. 902 Troxvell—Diceratherwm and the Diceratheres. Diceratherwm lobatum, sp. nov. (Fie. 6.) Holotype, Cat. No. 12487, Y. P.M. Probably from the true Diceratherium zone, Turtle Cove, John Day River, Oregon. The holotype consists of the anterior portion of a skull, collected in 1875 by William Day. Although slightly smaller than D. armatum, the new species shows a much greater complication of enamel, in which respect it is more advanced in its evolution; but it is more conser- vative in that it still possesses two incisors (see fig. 1 A, B, and C, comparing referred specimens of D. arma- tum). Dentition.—The premaxillaries are quite slender, both laterally and vertically, and extend well beyond the premolars. The first or median incisors are smaller in antero-posterior dimension than even those of D. annec- tens (see fig. 1) and are rounded and lobate rather than elongated and pointed in front. I? is more than half as large as [', an unusual thing for this tooth is commonly very small or absent. Both teeth are rounded and lobate as viewed from the side and resemble the form of an elk tooth; itis this feature which suggests the specific name. Fie. 6.—Diceratherium lobatum, sp. nov. Holotype. Cat. No. 12487, Y. P. M. Crown view of premolars and molars, excepting M’*, showing the complication of enamel and the cross ridges united by the ‘‘mure’’, m, a wall across the median valley. The designations of the ridges or lophs: ectoloph, protoloph and metaloph, apply both to molars and premolars; D, deuterocone, and T, tetartocone, to the premolars; Pr, protocone, and Hy, hypocone, to the molars. See also figure 1 C for premaxillary and incisors of the same specimen. 1/3. The premolars are distinctly bridged from loph to loph and united by a wall, which may be technically known as the mure, projected across the median valley effect- ively damming it up in such a way as to form the deep central pit completely surrounded by an enamel border. Troxell—Diceratherium and the Diceratheres. 2038 The mure is entirely absent from P* of D. armatum and is incipient on P?*. It is a feature of varying develop- ment in Cenopus and Metacenopus of the Great Plains also but is not homologous with the encircling protoloph of more primitive forms. | Premolar teeth seem to reflect most quickly the evolu- tionary changes of a race. Here are shown the crista and crochet, supplemented by numerous small folds giv- ing a distinctive air of advancement, features which were not simply lost by wear in D. armatum but which never existed. Both molars and premolars of D. armatum have deep postfossettes. In the new species, these are shallow and narrow and the metaloph rises from the posterior cingu- lum direct. The teeth have the appearance of being slightly longer-crowned than usual, and they have decid- edly straighter outer surfaces. In D. armatum there is a deep groove, especially on P+ just in front of the para- cone, and a second distinct ridge in the middle of the ectoloph. The development of the crochet and antecrochet in the first molar results in a closing of the median valley and | the raising of its floor a full centimeter above the deepest part. This is not homologous with the mure of the premolars. In M' of D. armatum there is scarcely a change of level of the valley bottom. The cingula are almost obsolete on the outer side of all teeth, but one is present about the protocone of each molar. There is a coating of cement on the outer sides of the cheek teeth. Whether or not this specimen had heavy nasals for the support of horns we have no way now of determining, but it is of minor importance since both types are well known among the John Day diceratheres and it is considered a sexual variation simply. A very large antorbital foramen was traversed by the blood vessels and nerves to the lips and face; indicating that there may have been a large facile lip like that of the African black rhinoceros of to-day. Am. Jour. Sci1.—FirtH Series, Vou. IT, No. 10.—-Octosmr, 1921. 14 we 204 Troxell—Diceratherium and the Diceratheres. Diceratherwm cuspidatum, sp. Nov. (Fie. 7.) Holotype, Cat. No. 12007, Y. P. M. Middle John Day, near Bridge Creek, John Day Valley, Oregon. The holotype of this new species consists of both maxillaries with all the cheek teeth save P?. As com- pared with D. armatum, the smaller specimens seem generally to be more progressive in the development of enamel folds on the teeth, and this new species, espe- cially, shows the complex pattern crenulations, together with additional cusps and irregularities of the cingulum to an unusual degree. Fic. 7.—Diceratherium cuspidatum, sp. nov. Holotype. Cat. No. 12007, Y. P. M. P* is missing. The teeth have many folds of the enamel and there are strong internal basal cusps. x 1/3. The species name is chosen because of the small conical tubercles arising from the floor of the median valley in the first and third molars, which in M? come to be high cusps 6 or 7 mm. tall and 4 mm. broad at the base, a feature unique in the rhinoceroses. Except for this internal cusp and a short segment of the cingulum, the valleys of the molars are open; they are not obstructed by the crochet and antecrochet as in D. lobatum and the slender protocones are not set off by distinct grooves from the antecrochet. A conspicuous style marks the outer end of the poste- rior cingulum on M?, but with the exception of M! neither molars nor premolars have a trace of cingulum on the outer side. The size is approximately that of D. annectens (fig. 3), but a marked difference is shown on the premolars by the criste and crochets, the cingulum encircling the deute- Troxell—Diceratherium and the Diceratheres. 205 rocone, and the shape of the medifossette inclosed, in P24, by a mure. As in D. annectens, P? is subquadrate, but the protoloph is less prominent and does not extend beyond the metaloph. The anterior portion of the ectoloph is not so prominent on any of these premolars, but in P? it is unusually subdued. A small internal basal cusp may be seen on this tooth also. P?+ each show the mure joining the two inner lophs. On these teeth the crochet is situated well out on the metaloph; it is not directed forward but inward toward the slender crista as though in anticipation of a continuous wall in later forms. In each premolar the metaloph is compressed and very narrow between the central and posterior fosse. The medifossette itself approaches a cylinder in form in that the sides are nearly parallel vertically; this marks a beginning of hypsodonty, and is a character to be noted in Menoceras cooki and other Miocene diceratheres. In this species the posterior nares extend forward to the first molar. Measurements of Holotypes. D.armatum D.lobatum D.annectens D. cuspidatum No. 10003 No.12487 No. 10001 No. 12007 Wer Ean po Poe PL MM. WP ve mm. mm. mm. mm. I’, ant.-post. diameter ..... 34* 20 2] P*, length, ant.-post. ...... 29 24 20 319 Width, transverse ...... 27 21 18 PesloneGh Skies hoo VO. 33 31 24 24 IWC EINY ay Fe cia Joss § Se bc 39 36 29 30 15 CTNGA 3 ee ek 39 38 29 28 ‘AVG IE Tes Edler ia ae Sn AT AT 35 36 Pee OCH) | RL LISA! hk. , 40 39 29 30 NTC S 2 co: appa altdaie, xi « 51 52 37 39 IM EMO GR ge. akc ea vas « 52 53 39 LG US ded ee esto Sera 53 54 4] ipston othe snr et. 2 fold bat 55 42 RUNGE EM ieee cece sticiags there 57 54 43 MESON OGM eh ert hceas . 5 ce.f AT 34 AWE AUIS eS oe 50 37 Molar-premolar length .... 254 . 3190 Molar series, length ....... 144 105 Premolar series, length .... 129 297 * Measure of plesiotype, No. 10005, Y. P. M., fig. 1 A. 206 Troxell—Diceratherium and the Diceratheres. Ture DICERATHERES OF THE GREAT PLAINS. Menoceras, gen. nov. Scarcely a more conspicuous or better known species of extinct rhinoceroses is mentioned in our literature than that which includes those specimens found and named by Peterson (1906) from the famous Agate Spring quarry on the ranch of Mr. Harold Cook at Agate, Neb. With the approval of Mr. Peterson, this species, Dicera- therium cooki, is here made the type of a new genus, Menoceras (pévos, strength, xépas, horn) and the following forms may be classed under this head, most of which Peterson considers invalid as species: Diceratherium cooki Peterson 1906. Genoholotype. Diceratherwum arrikarense Barbour 1906. Diceratherwum schaffi Loomis 1908. Diceratherium stigert Loomis 1908. Diceratherium aberrans Loomis 1908. Diceratherium loomisi Cook 1912. After a comparison with the genoholotype of Dicera- theriwm, D. armatum, with which it has always been asso- ciated, it is very clear that Menoceras is probably the farthest removed from Diceratherium of all the Miocene- Oligocene rhinoceroses. ‘This great difference was recog- nized by Peterson (1920), who ealls attention to the features of Menoceras cookz here briefly enumerated: (1) form of the horn cores (fig. 2), (2) form of the muzzle and anterior nares, (3) expanded zygomatic arch with rugose angles, (4) complication of the cheek teeth and union of the crochet with the ectoloph. Other distinctive features, widely differentiating it from Diceratherwm, are the smaller size, great geographical separation, unusual deepening of the pits and sinuses on both molars and premolars, almost complete absence of cingula, an extra transverse loph on the second deciduous premolar, and the closing of the external auditory meatus below. | It has been suggested by Peterson (1920) that M. cooki is derived from Cenopus mitis, a lower Oligocene species. C. dakotensis Peterson, also based on a lower jaw, but from the Protoceras beds, is considered by its author to be a connecting link because of the short symphysis and diastema, the curving of the lower border of the ramus, Propel aWiceratheriwn and the Diceratheres. 207 and the everted angle. A comparison with C. tridactylus proavitus offers a ‘further answer to the question of the ancestry of M. cookt, for in both we see the broad sagittal crest with converging straight lines, the heavy rugose angles of the temporal bone, and in the former an early stage of horn evolution. Cenopus tridactylus in the Oligocene shows foldings of > the enamel which may have given rise to the complex pattern of M. cookz, and it is reasonable to suppose that, just as favorable conditions must have influenced the opulent development of D. armatum in Oregon, so an unfavorable environment required a better dental mecha- nism and greater protection by the horns, at the expense of imcreased stature, on the Great Plains: M. cooki is scarcely two thirds as large as D. armatum. Fig. 8.—Milk teeth, Dp?*, of Diceratheriwm annectens? Cat. No. 12003, Y. P.M. For comparison with those of Menoceras cooki, see Peterson 1920, ply Gd, fig. 2.) $<: 1/8. The anterior portion of the skull and jaws (No. 12500, Y.P.M.) of a specimen of M. cooki was found by Pro- fessor Lull in 1908 near Rawhide Buttes, Wyoming, show- ing the distribution of the species in places other than the Agate Spring quarries. Metacenopus egregiwus (Cook). M. egregws (Cook) has for its holotype a fine skull and portions of the lower jaws in the private collection of its author. Although the species is considered by Peterson (1920) to be a synonym of M. niobrarensis, it seems to warrant the rank of a subspecies at least, and in any case should be retained as the type of the genus so happily named. Important features of the genus are: the larger size, smaller horn rugosities on the male skulls, the simpler teeth, and a distribution limited to the Great Plains. From the shape of the skull and the incipi- 208 Troxell—Diceratherium and the Diceratheres. ent horn rugosities one is led to believe that its ancestor was Cenopus tridactylus and therefore closely related to the true Dicerathertum of Marsh. This genus may include the following species: Metacenopus niobrarensis (Peterson) 1906. Metacenopus peterson. (Loomis) 1908. Inadequate. Metacenopus egregwus (Cook) 1908. Genoholotype. Metacenopus gregoru (Peterson) 1920. Of doubtful - validity. M. petersont Loomis, whether or not it is specifically distinct from M: niobrarensis or M. egreguus, is of impor- tance as showing that the Agate Spring quarries have a variety of rhinoceroses, and not Menoceras cook alone. M. gregorw Peterson is specifically indistinguishable from M. egregwus; it is unfortunately based on a fairly complete skull but with characterless teeth; however, it is of interest in so far as it shows the spread of Meta- cenopus into the region of South Dakota. SUMMARY. In restudying the American horned rhinoceroses of Oligocene-Miocene time, one is impressed with the need of a systematic grouping which, first, will distinguish those of the Great Basin of Oregon, Diceratherwm Marsh, from those of the Great Plains; second, will differ- entiate that well known group of animals from Nebraska and Wyoming, here designated Menoceras cooki (Peter- son) gen. nov. from Metacenopus Cook; and third, will separate all from Aceratherwwm Kaup of the Old World. In the present paper, all the known species of dicer- atheres are classified, the more important ones are redescribed, and two new species are proposed from the abundant material collected by Professor Marsh. From this study the conclusion is reached that in the light of our present knowledge it can not be reasoned that a hornless rhinoceros is of an aceratherine species, for the adult male may have been well armed. 7 W. D. Matthew—Fossil Vertebrates. 209. Arr. XVL—Fossil Vertebrates and the Cretaceous-Ter- tiary Problem; by W. D. Marruew. Recent contributions to Science by Professor Schu- chert, Dr. Cross and Dr. Knowlton' have brought up again the old controversy as to the dividing line between Cretaceous and Tertiary formations in America. As the fossil vertebrate faunas afford an important part of the evidence on this dispute, very considerably increased by collecting and research in recent years, I have been asked to give a brief résumé of this evidence and of the conclusions to which my interpretation of it has led. Recent Additions to the Vertebrate Evidence. When the problem was discussed in 1913 by the Geological Society of America I contributed a paper? setting forth the data up to date especially as regarded the Paleocene formation. Since then considerable advances have been made in the study of the Vertebrata. I have been engaged jointly with Mr. Walter Granger upon a revision of the Lower Hocene mammals, now mostly published, and of the Paleocene mammals of New Mexico, still in progress.2 Mr. Gilmore has contributed two most valuable memoirs, one on the vertebrates of the Ojo Alamo formation, the other upon the reptiles of the Puerco and Torrejon formations of New Mexico. A very large amount of new information is now at hand as to the faunas of the late Cretaceous vertebrates of Alberta, partly in the published contributions by the late Mr. Lambe,’ Mr. Barnum Brown,® Professor Osborn’ and *Schuchert, 1921, Science, 53, p. 45, Jan. 14; Cross, 1921, ibid., p. 304, April 1; Knowlton, 1921, ibid., p. 307, April 1. * Evidence of the Paleocene Vertebrate Fauna on the Cretaceous Tertiary problem, Bull. Geol. Soc. Am., 25, pp. 381-402. * See. various articles by Granger, Sinclair and the writer, in Bull. Am, Mus. Nat. Hist., 1914-1919. * Gilmore, 1916, U.S. G.S. Prof. Pap. 98 Q, pp. 279-302; 1919, idem, Prof. Pap. 119, pp. 1-68. *Lambe, 1914, Ottawa Naturalist, vol. 27, pp. 130-135, 145-155; vol. 28, pp. 13-20; 1915, Can. Geol. Sur., Mus. Bull. No. 12, pp. 1-49; 1917, Ottawa Nat., vol. 30, pp. 117-123, vol. 31, pp. 65-73; Can. Geol. Sur., Mem. No. 100, pp. 1-84; 1920, Can. Geol. Surv., Mem. No, 129, pp. 1-79. ° Brown, 1914, Bull. Am. Mus. Nat. Hist., vol. 33, pp. 539-548, 549-558, 559- 565, 567-580; 1916, idem, vol. 35, pp. 701-708, 709-716; 1917, idem, vol. 37, pp. 281-306. “Osborn, 1917, Bull. Am. Mus. Nat. Hist., vol. 35, pp. 733-771. 210 W. D. Matthew—Fossil Vertebrates and Professor Parks,’ the major part unpublished. Mr. Gidley is still engaged upon the important mammal fauna of the Fort Union, but a portion of his researches are published and available. Dr. Schlosser has recently described? and illustrated a small collection of Cernaysian fossils in Berlin Museum, and discussed their affin- ities and geological correlation. Finally, but not least in importance, M. Teilhard de Chardin has been engaged upon a very able and thorough revision of the Paleocene and Lower Hocene mammal faunas of the Paris basin and has published a brief résumé of his conclusions.?° Characteristics of Late Cretaceous Vertebrate Faunas. In summarizing the vertebrate evidence it will perhaps be best to begin with the faunas above and below those in dispute, whose position in the Cretaceous and Tertiary respectively is beyond question. 1. The Judith or Belly River formation on the Red Deer River, Alberta, lies conformably beneath the upper part of the marine Upper Cretaceous Fort Pierre. Its position in the Cretaceous is undisputed. It is equivalent to a part of the Upper Senonian chalk of Western Europe Upper Cretaceous but by no means at the end of the conformable Cretaceous succession, as it is followed by the Maestrichtian and Danian divisions of the chalk representing a long period of time. It contains a splendidly preserved vertebrate fauna. 2. The Wasatch formations in Wyoming, New Mexico and elsewhere contain a vertebrate fauna of Suessonian, Lower Hocene, age, corresponding and very closely related to the fauna of the Argile plastique of the Paris basin and the London Clay of England. They have yielded a very large and varied mammalian fauna, and some reptiles, ete. Between these two undisputed horizons lie the for- mations under discussion. They belong either just above or just below the boundary line, a line whose precise position must be fixed either by precedent or by agree- ment. * Parks, 1920, Univ. Toronto Stud., Geol. Ser., No. 11, pp. 1-76. ° Schlosser 1921, Paleontographica, LXIII, pp. 97-144, 2 pl. * Comptes Rendus, Dec. 6, 1920, pp. 1161-1162. the Cretaceous-Tertiary Problem. 211 The Cretaceous fauna consists of six families of gigantic terrestrial reptiles, popularly lumped under the term dinosaurs, but belonging to two distinct orders, five families of chelonians, two families of crocodilians, one of rhynchocephalians, and two of mammals. The range of these families is shown in the accompanying table. Mesozoic g Cenzoic | | Sond ) eas eres) meh Sears Geologic Range of Vertebrate Fauna — a geo, 2 S FI Ess of Upper Cretaceous : H re A alte) RS ae Judith R. — Belly R. — Ojo Alamo. SS ets let fe El Oo a SAURISCHIA Deinodontide XE UKE EDS Ornithomimidz Xe XG ORNITHISCHIA Hadrosauride XG XG x Iguanodontide Xe x Ceratopside Xt IXOUX Scelidosauride Xe eX Nodosauridz DOES AX! XE CHELONIA Pleurosternidee x DEXe Baenide ENT ORG Xe XTX Plastomenidz x xX xX xX Dermatemy did xX XX X ------- Trionychide PCE ee sG DGD. GON PLESIOSAURS aoe x ICHTHYOSAURS xX SQUAMATA Mosasauridee SiS Gq 5 CROCODILIA Crocodilidee x >.>... eee CHORISTODERA Champsosauridee XO GTX MULTITUBERCULATA Plagiaulacidee XEN XS, Oe MARSUPIALIA Cimolestidee RO eX Dinosaurs are the dominant vertebrates of a Cretaceous land fauna, as plesiosaurs, mosasaurs, etec., are of the marine facies. The turtles include five families, one of which survives to the end of the Paleocene, three to the end of the Eocene (one with a few relatives still living in Central America), the fifth is still abundant. The crocodiles include Mesozoic marine groups, but the essentially Tertiary Crocodilide make their first appear- ance in the Upper Cretaceous. The mammals are all Metatheria, an essentially Mesozoic stage, and belong to the marsupial and multituberculate orders. Both these ‘orders occur in the Jurassic, Lower and Upper Cre- taceous, and the marsupials survive to the present day. 912 W. D. Matthew—Fossul Vertebrates and Characteristics of Paleocene Mammal Faunas. The principal Paleocene mammals in order of their importance, abundance and variety are: 1. Taligrada, two families, Periptychide and Panto- lambdide; limited to the Paleocene. 2. Condylarthra, two families, Mioclenide and Phena- codontid, the first limited to the Paleocene, the second surviving into Lower Eocene. 3. Carnwora, of the very primitive creodont families, Oxyclenide, Arctocyonide and Mesonychide, the first two surviving as rarities into the Lower Eocene, the last found throughout the Eocene. But the progressive Miacide also have a representative in the Torrejon. 4. Teniodonta, peculiar archaic types allied to the edentates. Two families, Stylinodontide and Conorye- tide, only the former surviving into the Hocene, as a rarity. : 5). Multituberculata are fairly common and repre- sented by several genera allied to the Lance and Belly River Plagiaulacide. They give a distinctly Mesozoic aspect to the fauna. A single specimen of a multi- tuberculate has been found in the lower Wasatch of Wyoming. | _ 6. Insectivora. Besides the Leptictide, which survive until the Oligocene, there are some genera of more uncer- tain affinities: Mixodectide peculiar to the Torrejon, Pentacodon supposed to be related to the Eocene Panto- lestide, and an interesting Zalambdodont genus Pale- oryctes. 7. Marsupials. The true opossums appear in the Puerco, taking the place of the nearly related but more archaic Cimolestide of the Judith and Lance. They last through to the present time, though always rare fossils. _ At the close of the Paleocene, in the Tiffany and Cer- naysian and especially in the Clark Fork, an increasing number of Hocene mammal groups are represented. The Plesiadapide of the Tiffany, Cernaysian, Clark Fork and Hocene are on the border between menotyphlan insect- ivores and Primates, and in the Tiffany the earliest true primate appears, a tarsiid (‘‘anaptomorphid’’).. Two primitive members of the Hocene oxyznid family and the Lower Hocene genus Coryphodon are found in the © Clark Fork horizon. These few precursors, however, the Cretaceous-Tertiary Problem. 213 are scarcely enough to affect materially the great faunal change that comes with the true Hocene, with its abundant perissodactyls, its artiodactyls, rodents, adapid primates, progressive creodonts, and abundant Coryphodon." The antique character of all these Paleocene faune is seen in their retention of primitive characters in teeth and feet, as urged by Cope long ago, and abundantly confirmed by our later studies. They stand in marked contrast with the prevalent fauna of the Lower Eocene (Wasatch), already much advanced in tooth and foot structure. They can only be understood as representing a varied, often specialized, but unprogressive series of faune, which was largely displaced at the beginning of the Hocene by a far more advanced one, the survivors linger- ing along for a time but dropping out one by one in spite of their continued specialization on their more archaic lines. Characteristics of Early Tertiary Vertebrate Faunas. In the following tabulation of range I have starred those families and orders which I regard as modernized and essentially Tertiary?” in type. It will be seen that some of them appear somewhat before the Wasatch, but the great majority make their first appearance at that Stage. The Tertiary land vertebrates consist principally of placental mammals, the greater part of them of modern orders (perissodactyls, artiodactyls, Carnivora, rodents, Primates, etc.) and including the ancestral stock of the modern quadrupeds; but in the Eocene there is also a " Coryphodon has been recorded from the ‘Montien’ upon the evidence of a tibia which I had opportunity to examine last summer through Dr. Dollo’s courtesy. It may be a large taligrade, or of some other group; it is not characteristically amblypod, still less Coryphodon. My doubt in 1914 in regard to the correlation value of this record was warranted by what I knew at the time regarding the evidence, and is now fully confirmed. Dollo has recently secured from the Orsmael locality many separate teeth of a tiny mammal, which when studied and identified will be very interesting and important. The criteron used is not the geological range as per the known record, but the fact that the principal evolution and specialization of the family, its differentiation from the generalized ancestral stock, took place during the Tertiary. Also, and supplementing this criterion when the data are insuf- ficient for definite conclusions as to the derivation and evolutionary history of the group, the evidence that it was most abundant, varied and flourishing during the Tertiary serves to indicate its essentially Tertiary character. 214 Paleo- cene W. D. Matthew—Fossil Vertebrates and Geologic Range of Vertebrate Fauna of the Wasatch Group. Suessonian or Lower Eocene. REPTILES CHELONIA Benidee Plastomenide Dermatemydide Trionychidz *Emydide *Testudinide SQUAMATA *Lacertilia, fam. div. *Ophidia, fam. incert. CROCODILIA Crocodilide BIRDS ?Gastornithide, ete. MAMMALS . CARNIVORA Oxyclenide Arctocyonide Mesonychide *Oxyenide *Hyznodontide *Miacideea INSECTIVORA Pantolestide, ete. Leptictide *Tatpide, Soricide MENOTYPHLA Plesiadapide ?Microsyopidee *PRIMATESD *Tarside * *Adapide *GLIRES¢C *Paramyide, ete. EDENTATA Metacheiromyidz TAENIODONTA Stylinodontide *'TILLODONTIA *Esthonychide * Tiliotheriidz CONDYLARTHRA Phenacodontide Meniscotheriidz Hyopsodontide ENTELONYCHIA Arctostylops AMBLYPODA Coryphodontide * Hobasileide *PERISSODACTYLA * Wquide *Tapiride * Lophiodontided *Titanotheriide * ARTIODACTYLA® *Dichobunidee *Entelodontide bi Puerco b bl bd 4 PS bel bd “Pd bd bd bd Torr.-—t. Ul, Pd pd bP Pd b Tiffany-Cern. Cenozoic Eocene Bib: Je 5 so Fs Bae go oe PS payee 4... Eons XX Kae x xX X X X X ------- X Ky, eee X:. Xk eee xX. xX xX Dee Xx Xt Roe x x xX X X X X ------- x xX x Ki Kp X | xe oe Xx. Xe eros xX X X 9. Te.< x 529 xe Se Ge. XX! be X X X ----------- xX X X ---- xX XS x Oe Xo xr Ol eek x x XS Ox x x as XX. K Ree xX. Ki KK oe ee ».P.GO.& X'X, X08 X ke Oe Xx. Xx ee eee 2 The modern families of Carnivora are derived from the Miacide. b The higher primates are probably a branch from the Tarsiide, but do not appear in the record until the Oligocene, and are unknown in the North American Tertiary. The Adapide are related to the lemurs. the Cretaceous-Tertiary Problem. 915 considerable minority of archaic orders which disappear in the course of the Hocene. Marsupials are rare, multi- ’ tuberculates have disappeared. The reptiles are repre- sented by modern families of crocodiles (Crocodilide), chelonians (Hmydide, Testudinide) etc., the Mesozoic groups having mostly disappeared, except that as with the mammalian orders some of the Cretaceous turtles survive, the Banide to the end of the Hocene, the Dermatemydide (rare) and Trionychide (common) to the present day. General Relations of the Faunas in the Disputed Formations. The formations that intervene between the undisputed Cretaceous and undisputed Tertiary are mostly non-ma- rine. They fall into two groups, one characterized as to its vertebrates by dinosaurs and metatherian mammals, the other by archaic placental mammals and no dinosaurs. The former have been generally referred to the Cre- taceous by vertebratists, the latter to the Tertiary, but distinguished as Paleocene in recent years as the marked faunal difference from the true Lower Hocene came to be - better understood. It has been assumed by most writers that the dinosaur faunas were all older than the placen- tal mammal faunas, and the line between the Cretaceous and Tertiary has been drawn between them. In my paper of 1914 I analyzed the evidence and showed that this was not really proven, and that there was reason to suspect that the Paleocene faunas were partly con- temporary with the latest dinosaur faunas, representing a different faunal facies rather than a real change of fauna. I also pointed out the marked distinction between the archaic placental mammals of the Paleocene and the modernized placental mammals of the true Hocene. I have no reason to change any of the conclusions there set forth, but the evidence in support of them has been extended and confirmed in certain particulars. ¢ The relationship of the Eocene rodents to the multitudinous later groups is in dispute. d The rhinoceroses probably branched off from the Lophiodontide. They first appear in the upper Eocene. e The higher Artiodactyla appear to have evolved during the Tertiary from primitive Old World stocks of Hocene and later age. They are not descended from those two families. 216 W. D. Matthew—Fossiu Vertebrates and Summary of New Evidence. 1. Mr. Gilmore’s description of the fossil vertebrates from the Kirtland and Ojo Alamo beds, underlying the Paleocene of New Mexico, confirms their correlation with the Judith or Belly River, upper Senonian, and my conclusion that while the Puerco or Lower Paleocene mammal fauna was later than the Judith River, there was no direct proof that it was not contemporary with or even slightly older than the Lance and equivalents. 2. The fossil mammals of the Fort Union described by Mr. Gidley confirm the view that they are Upper Paleocene. They may be equivalent to the Torrejon of New Mexico, possibly later, approaching the Cernaysian and Tiffany. This statement represents my own judg- ment. I donot know what Mr. Gidley’s opinion may be. 3. M. Teilhard has shown that the Cernaysian and with it probably the entire Thanetian of Western Kurope is the equivalent of the uppermost Paleocene of America, the Tiffany horizon. It is not, as had been previously supposed, as old or older than the Torrejon. He also emphasizes the sharp distinction between the Paleocene and the true Lower Hocene of the European succession, and the correspondence and close affinities of the new fauna that appears with the true Hocene in both Kurope and America. Dr. Schlosser, while his conclusions accord with those of M. Teilhard on most points, is disposed to regard the Cernaysian as somewhat older than the Torrejon; but for obvious reasons he had not the full data at hand for a decision on this point. 4. Mr. Granger and I have continued our work on the Paleocene mammals, confirming the position assigned to the Tiffany fauna, the distinctness of the Puerco and Torrejon faunas as lower and upper Paleocene, and the very marked break between the Paleocene and Hocene faunas. The Tiffany is not much older than the lowest true Hocene in time, but it is wholly Paleocene in type, lacking all of the Tertiary orders so abundant in the Kocene, with the exception of one family of Primates. do. Additional specimens of the rare mammals of the Belly River described by Dr. Smith Woodward and myself"? confirm my conclusion that the Lance and Belly. * A. Smith Woodward, 1916, Geol. Mag., vol. 3, p. 333; Matthew, 1916, Bull. Am. Mus. Nat. Hist., 35, pp. 477-500. the Cretaceous-Tertiary Problem. 217 River mammals belong to the same families, but that the Lance mammals are a more specialized and advanced stage. This conforms to the evidence of the dinosaurs and other reptiles, indicating that the Lance is consider- ably later in time than the Belly River but that no great migrational change in fauna occurred during that time. 6. ‘The researches upon the upper Cretaceous dino- saurs by Brown, Lambe, Gilmore, Osborn and Parks, have placed the correlation and succession of the later dinosaur-bearing formations upon a very broad and solid footing, so that it is hardly likely to be seriously ques- tioned or materially modified. The exact relations of the older phases of the Belly River and so-called Judith River in southern Alberta and northern Montana have been partly cleared up, but the complete results are not yet available.1+ Succession and Correlation of the Vertebrate Faunas as now understood. The Judith River formation of Montana containing the Ceratops fauna is interbedded with the Fort Pierre and its fauna is correlated with the Belly River. The Milk River dinosaurs may be somewhat older. These need hardly be discussed. The Ojo Alamo group in New Mexico (Fruitland, Kirtland and Ojo Alamo for- mations) contain a fauna correlated with the Judith and Belly River. The Lance of Wyoming, Hell Creek of Montana, Arapahoe and Denver of Colorado contain the Tricera- tops fauna. The same six families of dinosaurs are found, but some if not all are represented by more special- ized genera and species. The same groups of turtles, crocodiles and Rhynchocephalia are present, in some cases at least with more specialized representatives. The mammals (chiefly from the Lance) belong mostly, probably all, to the metatherian families Plagiaulacide and Cimolestide, but include more specialized genera than are found in the Senonian. Detailed comparisons indicate a very considerable lapse of time as measured by the phyletic changes, but no great faunal break or change, due to the invasion of a new fauna from elsewhere. 44 See Brown, 1917, Bull. Am. Mus. Nat. Hist., 37, pp. 281-282. 218 W. D. Matthew—Fossil Vertebrates and Close above the Lance and Hell Creek lie the Fort Union beds, devoid of dinosaurs, but not separated by any stratigraphic break, and containing a flora very closely allied to that of the Lance and to the upper Paleocene floras of Western Europe. OZ0Ie index fossils. _ J-115.- Collections of Fossils. ~~. Entomology: J-33._ Supplics. J-229. Life Pastones, J-230. Breit i Live Pups... : Zoology: J-223. Material for dissection. J-207, Diaseotion Bae a a Sak Ly pical. Animals, ete... J-88. Models. — pes Moro scone Slides: J- 189; Slides of Parasites, J-29. Cata- Bt oe se logue of Slides. \. aT a Taxidermy : J-22. North American Birdskins. Z-31. General Te tee . +. Taxidermy. ~~ > pes - Human Anatomy: J-37. Skeletons & Models. oe - es See J-228. 8, of Circulars & Catalogues, | Ward S ‘Natural Science Establishment : 84- 102 pueniers Ave, Rochester, N. Xs U. S. 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OF CAMBRIDGE, ePapeunsols HORACE i. WELLS, CHARLES SCHUCHERT, | HERBERT #). GREGORY, WESLEY R. COE anp _ FREDERICK K. BEACH, OF New HAVEN, “Bueretson EDWARD W. BERRY, OF BALTIMORE, "Das. FREDERICK L. RANSOME anp ee ee hs OF ON, 25 FIFTH SERIES — VOL. TI-[WHOLE NUMBER, OCII} "No. 11—NOVEMBER, 1921. -. NEW HAVEN, CONNECTICUT. 1921. TUTTLE, MORHHOUSE & TAYLOR CO., PRINTERS, 123 TEMPLE STREET. monthly. Six dollars per “yeat, in 1 advance. $6. 40 to countries in the Single numbers 00 cents; No. 271, one dollar. - at the Post Pee: at ‘New Haven, Comn., “under the Act Lat a age aes, oie. eae AGRIC ULIURAL GROLOGY By the late FREDERICK V. oe Ph.D. : formiaee Professor of Gene and Geologist OY the State Experiment Station, Louisiana State Sea é HIS book gives a definite idea of the processes and principles of sholoeee with especial reference to the geology of soils and of mineral ‘fertilizers. The matter and treatment are the outgrowth of several years’ teaching experi- ence. Useful features are the usable Dinner and lists - soil and geo- : logical maps. Since its publication, Emerson’s cts orioultaeal Geology” has been intro- duced as the required text-book in eb institutions, as follows: - Ohio State University . . North Carolina State Collénd= University of Tennessee - |. Massachusetts Agricultural College a New Mexico College — . University of N ebraska University of Missouri eh St. Olaf-College © State University of Kentucky 3 Parsons College Syracuse University — Grove City College. Southwestern Louisiana Industrial Institute : Utah Agricultural College Michigan Agricultural College Towa State College . University of North Carolina Salem College = College of Agriculture, Los Bafios— Clemson Agricultural College eo Oregon Agricultural College University of Georgia Virginia Polytechnic Institute University of Cincinnati Texas A. & M. College a -| Indiana State Normal School —_- This nei is a striking testimonial of the recognized ee Af Professor Emerson’s book for classroom use. 319 pages. 6 by 9. Fully illustrated, with many — Cloth, $3.00 postpaid Send for Free wien tues pe of this or any other Wiley book—they may be returned if not satisfactory. JOHN WILEY & SONS, Inc. 432 Fourth Avenue, New York | London: Chapman & Hall, Ltd. Montreal, Quebec: Renouf Publishing Company. Assi 8 i ay THE AMERICAN JOURNAL OF SCIENCE [FIFTH SERIES.] Arr. XVIL—The Crystal Structure of Alabandite (MnS); by Ratpo W. G. Wyckorr. Method of Investigation—The determination of the erystal structure of this mineral furnishes an illustration of the manner of combining, as a source of the data upon which to base the study of the structure of a crystal, (1) the reflection measurements from a single face of a erystal, which give the absolute dimensions of the unit cell together with the number of chemical molecules to be essociated therewith, and (2) reflections from the pow- dered substance. The general method of obtaining the structure of the crystal from these data is the same. which has previously been used! and is based primarily upon the analytical results of the theory of space groups. The Crystallography of Alabandite-—The specimen used for this investigation was a cube nearly a centi- meter upon a side. Alabandite is usually assigned to the tetrahedral class (hemimorphie hemihedry) of the cubic system on the basis of its showing tetrahedral faces and faces of the form (211). From the existing ecrystal- lographic evidence, however, it seems equally capable of assignment to the tetartohedral class of symmetry. The Number of Chemical Molecules within the Unit Cell—A comparison reflection photograph of the L series lines of tungsten using as gratings the (100) face * Ralph W. G. Wyckoff, this Journal, 1, 138, 1921; ete. * Ralph W. G. Wyckoff, this Journal, 1, 127, 1921, and other work as yet unpublished; P. Niggli, Geometrische Krystallographie des Discontinuums, Leipzig (1919). * This material was loaned by the United States National Museum through the courtesy of W. F. Foshag. Locality: Puebla, Mexico. . Museum No. 19565. Though its exact composition is unknown, it seems to be quite pure manganese sulphide. Am. Jour. Sc1.—F rts Seriss, Vou. II, No. 11.—Novemser, 1921. 17 240 Wyckof—Crystal Structure of Alabandite. of calcite and the (100) face of the crystal of alabandite was prepared in the usual manner. From the known reflection from calcite an accurate measurement was obtained of the distance from the reflecting crystals to the photographic plate; this determination was then used in the calculation of the spacing of alabandite. From the application of these measurements to the usual equation nk = 2d sin 6, (1) a mean value of d1o./n, where dj, is the length of the side of the unit cube and » is the order of the reflection, for this crystal of alabandite was found to be din, /f = 2.607 X)10% emi The density of this mineral is variously stated to lie between p==3.95 and p—4.04.4_ From a knowledge of the spacing against the cube face and of the density of the substance the ratio of the cube of the order of the reflec- tion, n, to m, the number of chemical molecules associated with the unit cube, becomes with the aid of n?/m = M/(d,,,/r)° X p (2) (where M is the weight of a single chemical molecule of the compound) n*/m = 2.038 when p = 3.95, or N/a = 1.994 swihlene tp =A 304" From this it is evident that the measured reflection is either the second-order one from a crystal whose unit contains four chemical molecules or a fourth-order reflec- tion from one having a unit composed of thirty-two chemical molecules. The Possible Arrangements of the Atoms within the Unt Cube.—If alabandite has tetrahedral cubic symme- try then it must be assignable to one of the space groups showing a hemimorphic hemihedry; if tetartohedral, it must have the symmetry of one of the space groups T?”. Four Molecules in the Unit.—Two space groups, Ta’ and T°, having the symmetry of the hemimorphic hemi- hedry, furnish two special cases with four equivalent positions within the unit ecell.® Three tetartohedral *P. Groth, Chemische Krystallographie, I, p. 146. > These results are taken from tables, yet unpublished, which give a com- plete analytical representation of the theory of space groups. Wyckoff—Crystal Structure of Alabandite. 241 groups, T’, T?, and T*, likewise have special cases with four equivalent positions. These special cases are as follows: Tetartohedral symmetry: Space Group T": 4a wwu; vit, wun, “iu. Space Group i ie Ab 000; 340; 202; Ooy 4c 444; 004; 040; 300. 444 BG ta 3) ad Space Group T’*, 4f uuu; ut4,4,—u,a,; tu+4,4—Uu; $—-U,t4,u+s. Tetrahedral symmetry (hemimorphic hemihedry) : Space Group T,’: Aa. Space Group Ty’: 46, 4c, 4d, 4e. From these special cases all of the possible ways of arranging the atoms in a unit of alabandite which has four chemical molecules within it are as follows: (I) Mn: www, wan, nui; wan. DC te a On the basis of the symmetry of the arrangement of its atoms this structure would possess tetrahedral symmetry. (II) Mn: 000; 440; 404; O44. S: 444; 004; 040; 400. The symmetry of this arrangement is the complete symmetry (the holohedry) of the cubic system. If a erystal having this arrangement of its atoms exhibits a lower symmetry than the holohedral, as alabandite does, this low degree of symmetry must be accounted for by some such effect as a dissymmetry in the shape of the fields of force surrounding me atoms. (III) Mn: 000; $40; 404; 04 S: pales ° aa - 4443 rede 3 fae; 444° The symmetry of this arrangement is tetrahedral. The other arrangements deducible from the space groups T? and T,? are capable of reduction to this same arrange- ment. (LY) Mini: wane, Ut 4 S: ulu'ul wu’ + ~~ © 2942 Wyckof—Crystal Structure of Alabandite. The symmetry of this arrangement is tetartohedral. It may be noted that arrangements (II) and (III) are special cases of this arrangement. Thirty two Molecules in the Unit.—It has already been shown in the course of the treatment of a somewhat simi- lar case® that with the present lack of precise knowledge concerning the mechanism of scattering it is impossible to rule out with certainty the complicated structures having thirty-two molecules associated with the unit cell. Such an elimination is equally impossible in the present instance. It consequently becomes necessary, for the present at least, to make the assumption that the correct structure is simple. In this case it is to be © assumed that four molecules of MnS are to be associated with the unit. The Choice of the Correct Structure Be -Alabandite.— The fee he lof [= =) | a | o cos 2 mn (hx, + ky, + lz Ja ue = | sin 2 an (hz, + hy, +l) | a (where I is the ee of reflection, f(d/n) is some function of the spacing between like planes of atoms, and o,, the scattering power of the atom r for X-rays, seems to be roughly proportional to the atomic number, the summation is to be carried out over each of the atoms (coordinates=ayz) within the unit cube), has been used to obtain a measure of the intensity of reflection to be expected from any plane (hkl) for any conceivable arrangement of atoms within the unit cell of a crystal. The two arrangements (II) and (III) are in a sense limiting structures for the less simple ones (I) and (IV); thus, (II) results from (I) by assigning to uw and w’ the values % and %4 (and for convenience in computation transferring the origin to the point (34343,)). Sunilarly both (IL) and (IIL) arise from (IV) by. assigning to w and wu’ the values 0 and 1% for (II) and for (III) the values 0 and 14. These two limiting cases, (II) and (III), can be most simply distinguished in their diffraction effects by a consideration of the reflections from the plane (111); the simplest plane all of whose indices are * Ralph W. G. Wyckoff, this Journal, 1, 138, 1921. Wyckoff—Crystal Structure of Alabandite. 248 odd. Writing A for the evaluation of the cosine terms and B for the corresponding sine terms, the application of expression (3) to these two possible arrangements leads to the following: Arrangement (II): Wepsoe (0) @)\ ee Be) When the indices are two odd and one even: A= 0. when. 7 — odd, A =4Mn + 4S, when n = even, B =0 always. When the indices are two even and one odd: A= 0, when n= odd, A =4Mn- 48, when 7 = even, B=0 always. When the indices are all odd: A =4Mn — 48S, when n = odd, A =4Mn + 4S, when n = even, B = 0 always. Arrangement (III): Toc f(d/n) x (A* +B’). When the indices are two odd and one even: A*= 0, when n = odd, A = 4Mn-4 48,-whenn = even, B= 0 always. When the indices are two even and one odd: A = 0, when n = odd, A =4Mn = 48, — when n = 2, + whenn = 4, B = 0 always. | When the indices are all odd: A= 4Min) B= 4S; when n = odd, A =4Mn = 48; — whenn =2, + whenn = 4, B= 0. From these two sets of expressions it is evident that if the arrangement of the atoms of alabandite is that of (II) or is an arrangement of (I) lying close to (II) then the first order reflection from the (111) plane must be weak; if on the other hand the grouping is that of, or approaches close to that of, (III) then this reflection must be great. Hence a study of the relative intensity of this reflection and of the reflections from other strongly reflecting planes will serve to distinguish between these limiting cases ‘qdvasojoyd sopMmod oy} uodn ATyoorrp u/p Fo sonyea oyeurxordde Surpvor 1oF [NZosn o[wos W—'T “DLT 244. Wyckoff—Crystal Structure of Alabandite. and to locate the atoms of manganese sulphide with all of the accuracy which the present knowledge permits. In this instance this comparison is most readily carried out by a study of the powder reflection. The Powder Photograph.—A small piece of the crystal of alabandite was powdered, formed into a film with collodion as the binding material and a powder photo- graph prepared in the usual manner using molybdenum radiation which had been rendered monochromatic by a zirconium oxide filter.’ The reflections were regis- tered upon a hemicylindrical film so that spectrum lines were obtained upon either side of the undiffracted image of the slits. Measurements of the distance of these refiec- tions from the zero image were made by halving the distance between corresponding spectrum lines on either side of the center. A check was furnished by observing the coincidence of the zero lines as determined in this fashion. ‘The spectrometer was standardized through a measurement of a sodium chloride spectrum. Accurate spacings of the planes producing each of the lines in the spectrum were determined with the aid of the usual expression MVCN ated ave oR OAS neg Soares 2: etre: 5): (1) by remembering that the ratio of the distance of a spec- trum line from the central image to the distance from the powder to the film measures 26 in radians. For the identification of the different lines and for their approxi- mate measurement, a scale constructed for the particular spectrometer used and reading the values of the spacings, d/n, directly, is very convenient (figure 1). An approximate calculation of the relative intensities of the reflections from the simple planes, which will furnish the strongest spectrum lines in the powder pho- tograph, can be readily made for each of the possible arrangements with the aid of the intensity expressions already derived for these groupings. For the reasons already outlined these computations need be extended only far enough to include the first order reflection from the (111) face and the reflections from two or three other simple planes which will serve as comparisons. Before these calculations can be made, however, it is 7A. W. Hull, Phys. Rev. (2), 10, 661, 1917. Wyckoff—Crystal Structure of Alabandite. 245 necessary to assign a value to f(d/n). An approach to the correct form of this function seems to be furnished by writing FAG ei —— (ye). Introducing this approximation and remembering that the intensity of the powder reflection from a kind of face is given by the product of the intensity of reflection from one of the faces into the number of like planes, such calculations yield for the four strongest lines. For the grouping (II): Plane Order (7) d/n I Intensity (of powder reflection) 100 2 0.500 6,670 40,000 units (arbitrary) 110 2 04 2,460 29,600 120 2 223 1,325 31,800 112 2 204 1,115 26,800 For the grouping (IIT): Plane Order (7) d/n I Intensity (of powder reflection) 111 i 0.577 4,680 37,400 110 2 BbY BEES 40,000 143 1 801 1,270 30,500 112 2 204.0411 26,700 The estimation of intensity and measurement of spac- ing for the four strongest lines in the powder photograph furnish 3 d/n Estimated Measured Calculated for the Plane Intensity Zao AU. 2.60 A.U. 100 2 10 1.84 1.84 110 2 8 SN 1.16 120 2 6 1.06 1.06 112 2 5.5 From a study of these measurements it is evident, assuming of course that four molecules are associated with the unit cell, that the arrangement of the atoms of alabandite is described by (II) or by such values of uw and uw’ in either (I) or (IV) that the arrangement approaches 246 Wyckoff—Crystal Structure of Alabandite. that of (II). A definite choice between there three possi- bilities upon the basis of a study of their diffraction effects cannot be made until the scattering powers © MANGANESE eo SULPHUR: Fie. 2.—The arrangement of the atoms in alabandite if it has exactly the ‘“sodium chloride arrangement.’’ of the different atoms for X-rays is known with accuracy and until the form of f(d/n) is carefully determined. If the atoms le exactly in the ‘‘sodium * Other weaker lines appear in the powder photograph. As will be seen from the following table they are in equally good agreement with the ‘“sodium chloride arrangement,’’ (II), or a close approach to this grouping. Calculated d/n Estimated (for IT) Measvred Calculated for the Plane yn Intensity Intensity 1.50A.U. 1.50A.U. id ae 3 17,700 units 1.31 1.30 100 + 2 10;000 0.851% 0.87 122 2 2 17,700 0.83 0.83 130 2 2 16,000 At least a portion of the lack of quantitative agreement can be ascribed to the approximate character of the assumption that f(d/n) = (d/n)?. Wyckoff—Crystal Structure of Alabandite. 247 chloride arrangement,’’ (II), then the observed low degree of symmetry must be ascribed to some sort of a lack of symmetry in the shape of the fields of force about the atoms of manganese or of sulphur or of both. If the low degree of symmetry is in this instance to be accounted for by the arrangement of the atoms and if the symmetry is really that of the tetrahedral class © MANGANESE 6 SULPHUR. Fic. 3.—A possible arrangement for the atoms of alabandite. The posi- tions of the manganese and sulphur atoms can be but slightly displaced, how- ever, from the positions which they occupy in the grouping of figure 2. This arrangement is a possible one only if the symmetry of alabandite is tetartohedral. (hemimorphic hemihedry), then grouping (1) with values of u and w’ such that there is but slight departure from the ‘‘sodium chloride arrangement’’ would be in agree- ment with the existing information; if, on the other hand, the symmetry is tetartohedral, a similar arrangement based upon (IV) would be possible. The definite elimi- nation of this last possibility could be effected if a careful crystallographic investigation showed the crystal to be 248 Wyckoff—Crystal Structure of Alabandite. tetrahedral. This seems never to have been done and the author does not have at his disposal material upon which to make such a study. The three possible struc- tures for alabandite are shown in figures 2, 3 and 4. Alabandite is usually classed in the same group with zinc blende.° This determination of its crystal struc- ture, however, definitely indicates that it is in no way © MANGANESE ® SULPHUR Fic. 4.—The last of the three possible structures for alabandite. In this ease also the positions of the manganese and sulphur atoms can differ but slightly from those of figure 2. isomorphous with the zine sulphide. In this connection it is of interest to note that alabandite does not have the dodecahedral cleavage of zine blende but rather the cubic cleavage of the (from the standpoint of its crystal struc- ture) similarly arranged sodium chloride and magnesium oxide. *The proof that the crystal was actually tetartohedral would not in a corresponding manner eliminate (1) since it is a special case of T? as well as of T,?. ** Dana, System of Mineralogy, 6th Edition, p. 59. Wyckof—Crystal Structure of Alabandite. 249 Taking its crystal structure as a criterion, one would say that alabandite is in chemical nature also similar to magnesium oxide in that it is composed of divalent ‘‘ions’’ of manganese and of sulphur."! Summary. By a combination of a reflection spectrum from a known crystal face with a powder reflection, and employing the general method based upon the theory of space groups, it is shown that the arrangement of the atoms in alaban- dite is either that of the ‘‘sodium chloride grouping’’ or is a grouping approaching very close to this arrangement. Geophysical Laboratory, Carnegie Institution of Washington, Washington, D. C. July, 1921. ** Ralph W. G. Wyckoff, this Journal, 1, 138, 1921. 250 C. Stock—Cenozoic Mammalian Remans Arr. XVIIL.—Later Cenozoic Mammalian Remains from the Meadow Valley Region, Southeastern Nevada; by CHESTER STOCK. CONTENTS. Introduction. Previous knowledge. Occurrence. Comparison of faunas from the Meadow Valley Region. Description of Vertebrate Remains. Panaca beds, Meadow Valley, Nevada. Pliohippus?, sp. Rhinocerotid, possibly Teleoceras, sp. Pliauchenia?, sp. | Muddy Valley beds, Muddy Valley, Nevada. Merychippus?, sp. Alticamelus? or Procamelus?, sp. Descriptive list of collecting localities. Conclusions. Introduction. In the progress of investigations relating to problems of correlation of western Tertiary deposits, conducted under the leadership of Professor John C. Merriam at the University of California, it has become evident that an extensive territory of later Cenozoic beds in the Meadow Valley region of southeastern Nevada, mapped by Spurr! as Pliocene, has remained for a number of years a field from which paleontological materials indi- eative of Tertiary mammalian faunas were unknown. With the special purpose of examining the deposits for vertebrate remains, the writer accompanied by Mr. R. J. Russell visited Meadow Valley during the field season of 1919, at the request of Professor Merriam and in the interest of the Department of Paleontology, University of California. While fossil collecting did not yield the results that had been anticipated, sufficient materials were encountered in beds exposed near the village of Panaca in Meadow Valley, and again in Muddy Valley between the villages of Overton and Logan, to give some information as to age and relationship of these deposits. Information relating to the Meadow Valley region, although dependent upon an examination of a compar- * Spurr, J. E., Descriptive geology of Nevada south of the fortieth paral- lel and adjacent portions of California, U. 8S. Geol. Surv. Bull. 208, 1903. from Meadow Valley Region, S. Nevada. 251 atively small portion of the great area in which later Cenozoic deposits are exposed, appears worthy of record as it not only furnishes paleontologic data for correla- tion studies of the Great Basin Tertiaries, but may also be of service in an interpretation of the geologic history of the Grand Canyon of the Colorado. Previous Knowledge. We are indebted to the reconnaissance study of Spurr? for the first account of the geologic features of south- eastern Nevada. The observations which Spurr has recorded concerning beds determined as of Pliocene age in the Meadow Valley region will suffice for purposes of the present paper and need only receive attention. The group of deposits so determined includes the sedi- mentary series of Meadow Valley typically exposed in the vicinity of Panaca, Lincoln County, Nevada, and discussed in the text of Spurr’s report although not indicated on the geological reconnaissance map which accompanies the paper. Beds similar in appearance to those occurring in Meadow Valley, but located some 30 miles south of Panaca, are mapped as Pliocene, the sedi- ments extending from this point to the south along the western base of the Mormon Range. They are well exposed in the Meadow Valley Wash. Along the Muddy River east of the Mormon Range and in the valley of the Virgin River the sedimentary strata, approaching closely in general appearance those exposed in the Meadow Valley Wash, are regarded by Spurr as probably of Pliocene age. | With reference to the accumulation of the Plocene series, Spurr remarks: ‘“As observed by the writer in the Meadow Valley Wash, they have the appearance of having been deposited in a lake, although it is possible that they represent the valley accumulation of the Colorado River, at a period when the streams of this system occu-. pied wide valleys, in which they worked laterally and deposited the material which they derived from the erosion of the mountains, the carrying power of the streams at that time not being equal to the amount of load received. These sediments occupy the older valleys which were eroded in thé Paleozoic limestones and in the “Spurr, J. E., op. cit., 1903. 252 C. Stock—Cenozoic Mammalian Remains earlier Tertiary sediments and lavas, but they were laid down before the down cutting of the latest sharp gorges, for they stand as the walls of these. They lhe against the Carboniferous limestones, and, as described by Marvine, against the Archean granites along the Grand Wash.’’ The basis for determination of age of the horizontally bedded sediments as Pliocene is given by Spurr in the following statement : ‘* According to Dutton (Second Ann. Rept. U. S. Geol. Surv., p. 67) the greater part of the general denudation of the Colorado drainage region was probably accomplished in Miocene time, whereas the cutting of the Grand Canyon probably began in the early part of the Pliocene. The conglomerates and sandstones under consideration were evidently deposited just before the period of rapid canyon cutting, and this, in conjunction with the evidence afforded by the underlying unconformable Tertiary rocks in Meadow Valley Canyon, may be sufficient grounds for specifying their age provisionally as Pliocene.’’ Everett Carpenter® in a paper on the ground water in southeastern Nevada discusses the Meadow Valley region. Concerning the geology of Meadow Valley, Carpenter states: ‘‘The valley fill consists largely of gravel, sand, and variously colored clay. Its depth is probably great. There are good exposures of the unconsolidated sediments in the valley, but no fossils have been found to give a definite clue as to the age. The three terraces on the alluvial slopes indicate that there have been at least three epochs of accumulation, which alternated with three epochs of erosion. The terraces and the erosional features in general are very similar to, and probably were formed. contempo- raneous with, those 1 in Las Vegas Valley, which are inousat to be Pleistocene in age.’ In the course of completion of the present paper there appeared an important abstract by Mr. C. R. Longwell of results obtained from a study of the geologic feature of southeastern Nevada in which particular attention is given to the region of the Muddy Mountains. In the descrip- tion of the Tertiary formations, Longwell notes the pres- ence of an older and younger series. The latter deposits occupy the intermontane valleys and are composed of silt, clay and sand to a thickness of nearly 2000 feet * U.S. Geol. Surv. Water Supply Paper 365, pp. 50, 58-59, 1915. * This Journal, pp. 39-62, January, 1921. ASHI —., NISPYEA ALY. oo / U Bu & ary |=] 49 | Fie¢. 1.—Outline map illustrating occurrences of Miocene and Pliocene faunas in Tertiary provinces of the United States west of the Wasatch Range. P, Panaca beds; M, Muddy Valley deposits; B, Barstow beds; Re, Ricardo beds; C, Chanae formation E-T, Etchegoin-Tulare beds and Merychippus zone; Or, Orinda beds; EH, Esmeralda beds; CM, Cedar Mountain beds, T, Truckee beds; MK, McKnight Miocene; V-T, Virgin Valley and Thousand Creek beds; I, Idaho beds; Ir, Ironside Pliocene; Hl, Ellensburg formation. 954 C. Stock—Cenozoic Mammalian Remains | The beds rest unconformably upon the older series and are tentatively considered to be of Pliocene age. These are the deposits referred to below as the Muddy Valley Beds. | Occurrence. Within the confines of the Meadow Valley region of southeastern Nevada at least two areas are known where well exposed sedimentary deposits, presumably of the later Cenozoic, have yielded mammalian remains. The northern area comprises Meadow Valley, an intermontane enclosure bounded on the west by the Highland Range, on the east and south by the Mormon Range, and on the north by the Pioche Range. Some 80 miles to the south of Meadow Valley, a second series of mammal-bearing beds flanks the southern extremity of the Mormon Range and is exposed in the valley of the Muddy River. Both areas le within the drainage basin of the Colorado system. Meadow Valley—The later Cenozoic sedimentary. deposits of Meadow Valley extend for approximately ' twenty miles north of the entrance to Meadow Valley Canyon and in a lateral extent reach perhaps a distance of ten miles or more. They are typically exposed near the village of Panaca. These beds rest unconformably upon older rocks of Paleozoic, Mesozoic, or early Tertiary age that form the borders of the valley. The deposits consist in part of red-brown and green colored sands and clays, not well indurated, exhibiting on their weathered slopes typical badland features. Cross-bedded sands and gravels as well as tuffaceous materials are also pres- ent. The sediments have either a horizontal position or show the effects of slight deformation. Meadow Valley presents striking physiographic features as a result of the terracing which the later Cenozoic beds have undergone. Fossil materials pertaining to a camel, a rhinoceros, and a horse were collected in exposures immediately south- east of Panaca. The designation Panaca beds may be conveniently applied to these mammal-bearing sediment- aries of Meadow Valley. Muddy Valley.—Terraced sedimentary deposits extend along the Muddy River for some ten miles northeast of the confluence of this stream with the Virgin River. Southwest of Muddy River, between the villages of from Meadow Valley Region, S. Nevada. 255 Overton and Logan, Lincoln County, Nevada, where the beds were examined in detail, they consist of well indu- rated sands and clays, red and light brown in color, that overlie unconformably the early Tertiary deposits in this region. A small vertebrate fauna, including camels and a horse, was collected in the fine sandstone approximately three miles west of Overton. The sedimentary deposits of Muddy Valley, in which mammalian remains were found, may be known as the Muddy Valley beds as dis- tinguished from the Panaca deposits of Meadow Valley. Comparison of Fawunas from the Meadow Valley Region. Unfortunately few species are represented in the Ceno- zoic faunas from the Meadow Valley region, and much additional vertebrate material must be secured before satisfactory comparison can be made between the mam- malian assemblages at present recognized by fossil remains in the Panaca beds of Meadow Valley and in the Muddy Valley deposits of Muddy Valley. Remains of Equide found near Panaca, Nevada, belong to large types presumably related to species of Plio- hippus or to early forms of Hquus...In contrast to the species from the Panaca beds, that from the Overton deposits, so far as evidence is procurable from a single incisor tooth, seems to represent an earlier stage in the ‘history of the horse group. The incisor from the Overton beds resembles closely in size comparable teeth of Mery- chippus. This genus occurs commonly in Miocene deposits of the Great Basin region. Among the fragmentary rhinocerotid remains obtained in the Panaca beds is a phalangeal element similar in size and shape to phalanx 1, digit 3, manus of Teleoceras jfossiger. Members of the Rhinocerotidae are known from the Tertiary deposits of western North America, but apparently are not found in deposits later in age than Lower Pliocene. Camel remains from the Panaca beds apparently belong to a species of the Plauchenia group, while materials from Muddy Valley are presumably referable to genera other than Pliauchenia. A fore-foot of an im- mature camel from the Muddy Valley deposits may belong to Alticamelus or to Procamelus, while a single Aw, Jour. cee SeRizs, Vou. II, No. 11.—Novemser, 1921, 1 256 C. Stock—Cenozoic Mammalian Remains astragalus from these beds, possibly pertains to the latter genus. Such evidence as can be gathered at present from the Figs. 2-7. . ™~™: 7 PAE NEY Au We > eg —= Figs. 2 to 6—Pliohippus?, sp. ,Hlements of the dentition and skeleton. Fig. 2, lower cheek tooth, No. 24094; outer view, « 1; fig. 3, proximal end of metacarpal 3, No. 24095, « 42; fig. 4, metapodial 3, No. 23931, « 14; fig. - 5, first phalanx, digit 3, No. 24097, « %; fig. 6, phalanx 2, digit 3, No. 24096, « %. Panaca beds, Meadow Valley, Nevada. Fic, 7.—Rhinocerotid, possibly Teleoceras, sp. Phalanx, No. 24093, pos- terior view, x %. Panaca beds, Meadow Valley, Nevada. from Meadow Valley Region, S. Nevada. 257 very incomplete faunal representations occurring in the later Cenozoic sediments of the Meadow Valley region suggests that the Panaca beds and the Muddy Valley deposits are not of same age. Furthermore, the beds in Meadow Valley appear to be younger than those of Muddy Valley in which fossil vertebrates have been found. The occurrence of a large type of horse in the Panaca beds favors the belief that these deposits are not. earlier in age than Pliocene, while the presence of a rhi- noceros, possibly the genus Teleoceras, indicates a period antecedent to the Pleistocene. The collection of ver- tebrate remains from Muddy Valley is not large enough to permit definite assertion as to age of the Muddy Valley deposits. If the single incisor tooth belongs to a horse related to Merychippus or to a closely allied form the sug- gestion may be advanced that the Muddy Valley beds are Miocene in age. Information obtained from a study of the camel remains appears conformable to this view. : Description of Vertebrate Remains. Panaca Beds, Meadow Valley, Nevada. Phoolippus?, sp. An unworn and fragmentary tooth, No. 24094,° fig. 2, locality 3548,° measures approximately 14mm. in trans- verse diameter across the hypoconid. ‘This measurement does not include the thickness of the outer layer of cement. ! Elements of the limbs secured at locality 3547 are shown in figs. 3 to 6. The limb materials indicate forms larger than species of Pliohippus from the Lower Pliocene of western North America. They approach in size comparable structures of the Pleistocene Equus. In specimens such as the median metapodial (fig. 4) and the phalanges of digit 3 (figs. 5 and 6) a size is shown which approximates closely that of limb elements of Plio- hippus proversus from the Upper Etchegoin Pliocene of California. : * Accession numbers refer to specimens in the collections of the Depart- ment of Paleontology, University of California. * University of California collecting localities. See descriptive list of localities near the end of this paper. 258 C. Stock—Cenozoic Mammalian Remains — Measurements of Limb Elements. “Metacarpal 3, No. 24095 Transverse diameter of proximal end................ 45.6mm, Anteroposterior diameter of proximal end............ 32.4 Metapodial, No. 23931 Greatest transverse diameter of distal end............ 42.5 Greatest anteroposterior diameter of distal end....... 33.2 Phalanx 1, No. 24097 Greatest lemon 224) ks ME eo aE ee T1238 Widthi of iproxamal (erid! (720k er OS BE Pe —A4T Depth of proximalsends 1... eee ee eias OR. OF ee 9329 Wadth vofdistaltends: 3 4ltay ogee 4etc Peer eee 38.8 Phalanx 2, No. 24096 Greatest: length ¢4hs4 (Ae heds = Aneel ae Avs a36 Widthtof prosimalend,. atc. scp anos) acter ee a ee a39 a, approximate. Rhinocerotid, possibly Teleoceras, sp. Fragments of teeth of a rhinoceros were collected in the terraced sedimentary beds of Meadow Valley near Panaca, Nevada. Unfortunately the specimens are not preserved in sufficient completeness to permit satisfac- tory determination. A single phalanx, No. 24098, fig. 7, found in association with fragments of teeth at locality 3546 resembles most closely in size and shape phalanx 1, digit III, manus of Teleoceras fossiger, from the Republican River beds of Kansas. No. 24093 differs from the specimen of Teleo- ceras available for comparison in possessing a proximal articulating surface relatively wider transversely. In this specimen, also, the proximal and distal articulating surfaces approach each other more closely on the posterior side, fig. 7, than in the corresponding phalanx of 7’. fossiger from Kansas. Measurements of No. 24093 Greatest transverse width ..... iio Maaelgatetee Bias | ee 52.4mm. Distance between articulating facets measured across middie of posterior faceriis. 44 sine ses soon 17.8 Greatest transverse diameter of distal facet .......... 39 from Meadow Valley Region, S. Nevada. 259 Plhiauchema?, sp. A nearly complete fore-foot, No. 23916, fig. 8, collected at locality 3546, belongs to a rather large species of camel presumably of the Pliauchenia type. A _ single astragalus, fig. 9, from locality 3547, is perhaps also referable to this genus. The individual represented by the fore-foot, No. 23916, approaches in size certain of the camel types known from the Ricardo Lower Phocene of the Mohave Desert, California. The Meadow Valley species resembles in size the Camelops-like* form from the Upper Etchegoin Pliocene of California, but it does not approach in this character the genus Camelops from the Pleistocene of Rancho La Brea. | The camel from Meadow Valley differs from Pro- camelus® from the Barstow Miocene of the Mohave Desert im possessing a shorter and more robust cannon bone, larger and heavier phalanges. No. 23916 is decidedly larger and heavier than limb elements of Procamelus known from the Upper Miocene Cedar Mountain beds of Nevada. The anterior cannon bone is badly crushed, particularly the posterior side. At the distal end the articulating surface for the inner digit is noticeably larger than that for digit 4. | | ~ Measurements of No. 28916. Carpus. } ‘Greatest transverse width across proximal row of car- Peelemlemis els . ACELOT OG ak Sta & 70.8mm. ‘Depth measured from proximal surface of scaphoid to distalsuriaee ok marmum yeah... ole ee ny. . 8: ay) Anterior cannon bone Ju C108: 7) Ee caer de Ge oak ee Oc ee : ae poe ae ee 336 By icine tte OOK UMM OIG. 9 Fook oa cK cp trcialtns ovine my slope DP O02 4 = a68 Bee iotubier@ cQShell: CMe Nie es eek 28 hg wie, cyesie = a 008 a92.5 Digit 4, phalanx 1 SHES AUSSIE GIST Tae So een PS eeepc > en TS Uhh Ok DEOXAmaleWe Mery ese MeL es oo ws oles Oe 41.3 7 Merriam, J. C., Trans. Amer. Philos. Soc., n. s., vol. 22, pt. 3, p. 38, figs. 42a and 42b, 1915. ® Merriam, J. C., Tertiary mammalian faunas of the Mohave Desert, Univ. Calif. Publ. Bull. Dept. Geol., vol. 11, p. 513, fig. 91, 1919. 260 C. Stock—Cenozoic Mammalian Remains — Depth of proximal end cc) gee ae a eee 30.2 mm. Width: of distal end’..--3 3. eee ae ee 34 Digit 3, phalanx 2 | | Greatest lensth-xeioxen eerie ieee c GI. ce ee O7.7 Width of. prommalendiad «sa ee ste. + eee eee 30 Depthsof proximal entdinc. 7:1); dosalane, mostly salic | : (sail: fem, <¢ i eeks > Oi ie salfemane, equal or nearly equal quantities of each (sal: fem < 5:3 > 3:9); dofemane, mostly femic minerals (sal fem’ <3 5 S47): and lastly perfemane, nearly or entirely femic (sal: fem < 1:7). ~The classes thus obtained are subdivided into orders on the relations of the salic minerals, quartz, feldspars, and feldspathoids (generally nephelite) to one another in the first three classes and on somewhat similar relations among the femic minerals in the last two. More minute consideration of the mineral oxides divides the orders into rangs, and the rangs into grads. The proportions by which they are thus divided are always the same as those by which classes are made. Further details regarding this system will be found in the work referred to. It is the most exact system that has hitherto been proposed, and is based upon the fundamental property of the rock—its chemical composition. Aside from this, its most striking feature is the recognition of the quantitative relations among the component rock-minerals, the bearing of which we. shall presently see. As must be the case in all petrographic sys- tems the divisional lines of classification are arbitrarily drawn, but they are carried out logically on a consistent plan. It has been much used in careful and exact work, but the requirement of the knowledge of the chemical composition of a rock, and the difficulty in many cases of obtaining this, has doubtless prevented its wider. extension. General Remarks on Classification. From what has been stated in the foregoing discussions the student will have doubtless perceived that the chief difficulties in the systems described, excepting the last one, have been two; first, the attempt to introduce simultaneously into one scheme too many of the different properties and affinities L. V. Pirsson—Classification of Igneous Rocks. 217 of rocks that we must consider, with the result of making the system confused, and second, the failure to recognize quantitative relations among the minerals, with the result of making it inexact. When we observe that which is to entitle one kind of rock to recognition as an indi- vidual entity is based on geologic occurrence and mineral composition, whereas another kind is based on petro- genetic relations and texture combined with mineral com- position, and a third is based on geologic Occurrence, geologic age, and the minerals, it seems clear that there is an attempt to accomplish too many things at one time. Leaving aside the matter of geologic age, three systems of classification, each of which endeavors to express something different from the others, have been telescoped together, and the result is to the advantage of none of them. It now seems clear that we need three systems of classi- fication of igneous rocks in order to express our knowl- edge of their properties and relations and that we may put like things together; these are: A. A petrographic classification based on those inher- ent characters of rocks, expressed by their minerals and textures, which shall define in a material way the kind of rock we are dealing with. This covers the idea, previ- ously stated, that a granite porphyry is a granite por- phyry, no matter where it occurs. B. A petrologic classification based on petrogenesis which attempts to group the rocks according to their family relationships and co-magmatic origin, as expressed by their relative geologic positions, and the evidences of consanguinity that they may present. Here, for example, the dike rocks of Rosenbusch would find logical expres- sion. This will be more fully explained later. C. A geologic classification based on the method of occurrence that determines the form of the mass of an igneous rock and its outward space relations to other rocks. This states whether it is plutonic or voleanic, whether a stock, laccolith, sheet, dike, ete. This kind of classification is generally explained in more or less detail in the standard text books of geology, and, with reference to intrusive bodies, has been quite fully elaborated by Daly.*® } ™ Classification of Igneous Intrusive Bodies, Jour. of Geol., vol. 13, p. 485; 1905. Also, Igneous Rocks and their Origin, p. 61, 1914, 278 DL. V. Pirsson—Classification of Igneous Rocks. Each of these classifications has distinct aims of its own, which can only be properly expressed by separate treatment. The aims of each are legitimate and entitled to full recognition; the difficulty has been that in mixing them together and insisting on one compound classifica- tion there has naturally resulted wide divergence of views as to what the aims of the classification really are. We may find an analogy for these classifications in the strati- fied rocks; in one system they are arranged according to their veologic age; and we speak of them as Cambrian, Jurassic, ete.; in another, according to the nature of the materials composing them, and we have limestones, sand- stones, etc.; again we divide them into series, stages, formations, ete. The geologic classification, it 1s presumed, is already familiar to the student, and need not be further consid- ered here. Petrologic classifications, with the meaning . mentioned above, have not yet been definitely and clearly stated. The nearest approach to one is given by Rosen- busch, but mingled, as has been shown, with the petro- graphic system. Brogger has stated principles that must be essential in their formation and has offered an example with the rocks of the Christiania region, some- what complicated with their geologic occurrence. Such a classification really belongs in the field of theoretic petrology, and should be given in a work treating of that subject. This book is devoted to descriptive petrography, and obviously the rocks should be treated in it according to a petrographic system; until the student has mastered this he is not in a position to comprehend fully a petro- logic one. For his benefit a preliminary attempt at a petrologic system is appended to that part of the book dealing with the igneous rocks. Petrograplic System of this Book. The petrographic system to be employed should be based on the inherent and fundamental properties that express the rock. The most important one is the chemical composition, but the ones that have generally been employed are the minerals and the texture, since these are the more obvious and readily determined. Moreover the chemical composi- tion can to some extent be recognized, provided attention is given to the quantitative relations of the minerals. In L. V. Pirsson—Classification of Igneous Rocks. 279 a text book also the classification should be formed in such a manner as not to cut the student off from the his- torical aspect of the subject, or from current usages, and the volume of literature that has grown up based upon them. For these reasons a system has been adopted that is founded upon the older qualitative one, with modifica- tions tending to greater definiteness in the statement of mineral composition, and at the same time a quantitative element has been introduced, and carried as far as seems advisable at present, in order not to introduce too great complexity into the scheme, and too great a departure from prevailing usages. The quantitative elements are derived in some degree from the quantitative chemical- mineralogical classification previously mentioned and the scheme is somewhat similar to that advanced by Iddings,'® but with important modifications. It is shown in Table No. 3. Explanation of Table No. 3. It should be understood at the outset that it is not intended in this table to present a scheme of classification that shall embrace all the differ- ent kinds of: igneous rocks that have been described and named. Many of these differ from common well-known types in modifications of texture, or the proportions of the minerals, or the presence of some other mineral in relatively small quantity, and are to be regarded as having the value of varieties. For simplicity’s sake only more common or important types are given for illustration in each division, and varieties are treated later in the descriptive part of the work. The rocks are divided into five large groups, oe bs, C, D and E, according to the nature of the feldspars that they contain. In A these are dominantly alkalic, ortho- clase, albite, etc.; in B, alkalic and sodacalcic, that is to say, mixtures of alkalic feldspars with plagioclase, as for example orthoclase and andesine or oligoclase. Various types of mixtures may occur, but the essential thing is that lime is associated in the feldspars in notable quan- tities with the alkalies. In C on the contrary the soda- lime feldspars dominate over or replace the alkalic and may run through oligoclase and andesine to labradorite. In D the alkalic feldspars have practically disappeared Igneous Rocks; vol. II, p. 347, 1909. 280. OV: Pirsson—Classification of Igneous Rocks. and the plagioclases are normally those rich in lime, from labradorite to anorthite. In E are the rocks that contain no feldspar, or only negligible quantities of it. In a chemical sense then we may say that the horizontal TABLE NO 8, PETROGRAPHIC A B 4 ALKALIC AND SODACALCIC DOMINANT ALKALIC FELDSPARS pinto! Characterized i 2 3. 4, by Felsie Mafic Felsic Mafic Quartz Monzo- QUARTZ and Granite. fy oc seek. Dee ees nite and Grano- diorite FELDSPARS Granite EL ORD Wee ne oa eee |Qt2. Mon. Pony) yee eae ae Rhyolite Dellenite’ ~ |... 522 ===a a 10. ie 12. 13. FELDSPARS Syenite Shonkinite Monzonite Kentallenite Syenite Porp’y |Minette and Vo-| “@onzon. porp’y | Camptonite (little or no Trachyte and YEO ety quartz or lenad) Bostonite Latite Trachydolerite Felenites 19 20. Pik 22 Neph - Syenite Malignite Theralite Essexite ‘ Group. ; Ne, FELDSPARS and Neph. Syen. (in part) (in part) LENADS (felds- Porp’y --------------- pathoids) Phonolite and Tephrites Tinguaite 28. 29. 30. dl. Lenites Bekinkinite LENADS | djolite/ Untite |Missourite Grp 9) -- a2 | : | Fergusite Neph. Leuc—& (little or no feld- | Group Moelilite:Basalte:||> t2s-- 23 32h ce ale sa ee Spar) Nephelinite |Nephelinite and Leucitite Leucitite(inpart)|| ---------------|--------------- (in part) Monchiquite arrangement represents a reciprocal relation between alkalies and lime. In the vertical direction the chemical relation expressed is that of silica (Si0,). When the silica is in excess over that amount required to form feldspars, etc., we have free quartz; as it diminishes quartz disappears; next, there is not enough to turn all the alkalies and L. V. Pirsson—Classification of Igneous Rocks. 281 alumina into feldspar, and a feldspathoid (lenad) appears; this increases with lowering silica until no _ feldspar is present. - The quantitative relation of the ferromagnesian CLASSIFICATION OF IGNEOUS ROCKS. © D E SoDACALCIC FELDSPARS CALCISODIC FELDSPARS No FELDSPAR 5 Ge fi 8 9 Felsic Matic Felsic Mafic Mafic Quartz Quartz Dilorice: sirens ise. ie Gabo Ree eee ae Us (DUO SEO OMY ae che pt eae Aes | et Boe Pee beeee ee HG eT SOLO MAVEN GRE Beene ek) oe Dacite =ss5 BREE SS tear Ne ecg tae hs Sr aia a gecguaer its Nees | aR a | 14 15 16 17 18 Diorite Anorthosite Peridotite Diorite Porphyry Gabbro and Norite Group Group : : Hornblendite Kersantite Diabase Pyroxenite Aare B Picrite and site asalt and Melaphyre Augitite 23 Q4. 25 26 27 Theralite Essexite Rouvillite Teschenite Jacupirangite (in part) (in part) Yamaskite Basanites Limburgite > d2 33 34 85 36 (mafic) minerals to the quartz, feldspars, and feldspa- thoids (felsic minerals) in the A, B, ©, D divisions is expressed under a felsic and mafic column in each. In one, felsic minerals dominate and form 50-100 per cent of the rock; in the mafic, the ferromagnesian ones dominate in like manner. - Other quantitative relations, like those affecting the felsic minerals among themselves, will be discussed later in appropriate places. 7 282 DL. V. Pirsson—Classification of Igneous Rocks. Texture in Classification. The factor of texture has so far never been given any very precise definition in classification. Different varieties of texture themselves have been minutely described, and, since textures merge into one another gradually in various directions and division lines between them must be arbitrary, quanti- tative definitions and limits to textures have been sug- gested, as set forth in the preceding chapter. But so far as textures have been used in systematic classification this has been done in a purely megascopic manner, and mostly with very vague limitations. Only the broadest distinctions are employed; divisions of granular, dense, and glassy are used, and whether the rock is porphyritic in fabric or not. No quantitative values as to the use of these distinctions are suggested. The greatest stress is laid upon the character of whether a rock is porphyritic or not; this shows itself in the terminology in that the term, as one of texture, is embodied in the name, either complete, as in syemte porphyry, rhombic porphyry, ete., or in the contractional suffix phyre, as in orthophyre, keratophyre, ete. All that Zirkel’® remarks as to the relation between texture (structure) and classification is that he lays stress on the con- trast between porphyritic and nonporphyritie rocks. He notes also that this gives rise to some inconsistencies, since some basalts are not porphyritic, but granular. Rosenbusch does not use tex- ture as a primary factor in classification, but only in a secondary sense as connected with mode of occurrence; when the latter is unknown he then falls back on texture, and the porphyritic quality plays the chief role. Brogger essentially follows Rosen- busch but has only offered an outline of his suggested classifica- tion. Iddings*' merely remarks that on the basis of texture the rocks are divided into the phanerocrystalline (grained) and aphanitic (dense) groups; the latter is subdivided into those with paleotypal, and cenotypal habits, this distinction being based on the appearance of the rock due to more or less alteration from, in general, greater age,?? as suggested by Brogger. Harker?® does not use texture in primary classification but, in general, follows Rosenbusch and Brogger in relegating it to a secondary position. These examples will serve to show that no general agreement either as to the use of texture in classification, or if used, as to its limits, obtains among petrographers. 2° Lehrbuch der Petrographie, Vol. I, p. 837. *t Tgneous Rocks, Vol. I, p. 350. OP. Clix p..000. * Petrology for Students, 3d Ed. 1902. L. V. Pirsson—Classification of Igneous Rocks. 288 One reason for this is the feeling that as a character its importance is secondary to chemical-mineral composi- tion, and another, that if all the various ramifications of texture, strictly defined, were introduced into a primary system of classification as divisions in one direction, and mineral groupings as divisions in another direction, the variety of rocks produced would be bewildering in num- ber. Nevertheless the texture of a rock has always been held to be one of its most obvious features and the recog- nition of it, in the simple forms mentioned above, is seen in classifications, either directly or indirectly. We pro- pose to employ it in a megascopic manner, but will attempt to give it a more precise definition than is usual, for the benefit of the student. The scheme is as follows: Grained Rocks; mineral constituents megascopically determinable. A. Apparently even-granular in fabric; fine to coarse; rarely subporphyritie. | B. Daistinetly porphyritic in fabric. 1. Groundmass grained, constituents determinable. 2. Groundmass dense, but sempatic to presemic; pheno- erysts determinable. Dense and Glassy Rocks; constituents mostly or wholly ondeterminable. C. 1. Porphyritic, but sempatic to prepatic. 2. Nonporphyritic. This is probably as far, in preciseness of definition, as it is wise to go at present; to be more detailed would introduce such radical differences with the existing litera- ture as would confuse the mind of the student, and greatly hinder his use of it. As it is, the scheme introduces a number of differences, not however of major importance, and these will be pointed out in proper places. We have then three textural divisions, which may be summarized as A, granular; the names of these rocks are shown in the table in bold-face type; B, porphyritic, in italics, and C dense or glassy, printed in roman type. The fragmental volcanic rocks, the tuffs and breccias composed of dust, ashes, bombs, ete., might well form a fourth textural division, but for the sake of simplicity 284 L. V. Pirsson—Classification of Igneous Rocks. of treatment they are not subdivided into groups in this book but are considered ina section by themselves, as will appear later. It is obvious that the character of rocks, which texture affords, might be employed for classification at the very besinning, or after the rocks have been separated by mineral grouping. In either case the final result would be the same, so far as classifying and naming the rock is concerned. In the first case, if rocks are first divided into granular, porphyritic, and dense classes. and then subdivided on mineral composition, we should have three such tables as No. 2 to refer to; whereas, if the texture is applied after the mineral grouping, the whole can be condensed into one table, as has been done, with greater convenience of reference. It is not, however, a necessity that we should follow the latter -plan in describing the rocks for the benefit of the student. Itis very much easier and more logical for him to take up the coarser-grained rocks first; he can learn to make his determinations of the minerals, and their groupings and relative quantities and relations, which settle the classification, much more quickly and accur- ately, with them, and the knowledge thus gained can then be applied efficiently to the more difficult fine-grained and - dense rocks. Moreover, in this one follows the usual mental course of procedure in determining a rock: we first examine the rock megascopically and notice whether it is sufficiently coarse-grained to permit us to recognize the component minerals; we study them and then assign the rock to its proper position i in the scheme of classifica- tion we have in mind. T. Holm—Studies in the Cyperacee. 985 Arr. XX.— Studies in the Cyperacee; by TxHro. Hoim. XXXII. Carices aeorastachye: Crinite nob., Aperte nob., and Magnifice nob. (With 8 figures drawn from nature by the author.) Crimte. This section is a small one, comprising only C. crimita Lam., C. gynandra Schw., and C. maritima O. F. Muell. Characteristic of these is the light-green or yellowish color (C. maritima), and the aristate scales. C. crinita is widely distributed from Newfoundland, Quebec and Ontario south to Florida, Louisiana, west to Minnesota and Texas; C. gynandra is distributed from Newfound- -jJand toWisconsin, and in the mountains to Georgia; they inhabit swales and damp thickets. C. marituma, on the other hand, grows in brackish or saline shores from Labrador to Massachusetts, and in Hurope along the coast * of Sweden and Norway to the White Sea. Carex crimta is a stately species reaching a height of ‘about 1.5 m.; the rhizome is cespitose, and develops several purely vegetative shoots, beside the floral, which are phyllopodiec, flowering already in the first year, and surrounded by several green leaves at the base. The © staminate spikes are generally two, the pistillate from three to six, remote and quite long, narrowly and evenly cylindric, dense-flowered, long-pedunculate and _ pen- ~ dulous. With regard to the distribution of the sexes, this is very variable; the terminal spike is not always purely stami- nate, but very frequently it is androgynous, 1. e. staminate above, pistillate below; or, though seldom, gynzecandrous with pistillate flowers at the apex. In many specimens, collected near Clinton, Md. the terminal spike was only staminate in the middle, pistillate at the apex and base; in a few specimens from Quebec the terminal spike was purely pistillate. The pistillate spikes vary from purely pistillate, the most frequent, to androgynous; both types may occur on the same specimen. A somewhat peculiar structure was observed in a few specimens from Clinton, where there was a bract below the terminal, staminate spike subtending a single pistillate flower; sometimes the 4 : 2 3 4 Fic. 1. Inflorescence of Carex aperta Boott; specimen from Columbia River, Washington; natural size. Fig. 2. Inflorescence of C. aperta forma concinnula nob.; specimen from Mt. Paddo, Washington; natural size. Fig. 3. Inflorescence of C. aperta forma hydroessa nob.; specimen from Columbia River, Washington; natural size. Fic. 4. Perigynium and squama of typical C. aperta; enlarged. Fie. 5. Pistillate squama from near the base of the lowermost spike of C. crinita Lam.; enlarged. Fic. 6. Perigynium of same; enlarged. Fic. 7. Pistillate squama from near the base of the lowermost spike of C. gynandra Schw.; enlarged. Fic. 8. Perigynium of same; enlarged. T. Holm—Studies im the Cyperacee. 287 rhachilla had grown out bearing a small staminate spike similar to the case we have described and figured in this journal (1896, p. 214, fig. 4). The squame of both sexes vary from oblong ovate, acuminate to emarginate, and the midrib is extended into a thick, rough arista of variable length; the arista is always much longer in the scales of the basal flowers than in the apical, and much longer in the pistillate spikes than in the staminate. The small perigynium is thin, green, eranular, inflated, ovate to obovate, with a short entire beak; only the two marginal nerves are present, and the perigynium is spreading at maturity, longer and broader than the body of the subtending scale. The very small caryopsis is deeply constricted at the middle. Carex gynandra was first described by Lewis D. de Schweinitz' as a distinct species, but in his monograph of the North American species of Carex, edited by John Torrey,” it is enumerated as a-variety of C. cramta with the remark, however, that ‘‘it may prove to be a distinct species.’’ Its characters are pretty constant, but some- times it appears to pass into the ordinary C. crinita. It has much the appearance of C. miliacea, but it is easily distinguished. By Boott*® it was accepted as a species. It resembles C. cramta in habit and size, in the number and length of the spikes, but the perigynia are ascending, less inflated, more or less elliptic, and distinctly nerved, 1. e. there are two marginal nerves, and three shorter, rather faint between these on both faces of utriculus; the arista of the scales is much shorter than in the former species, beside the body of the scale being entire instead of emarginate. The number of staminate spikes is mostly 2, and they are very seldom androgynous; the pistillate spikes are mostly four, and they are com- monly androgynous. It represents undoubtedly a distinct species. | | Carex maritima has a stoloniferous rhizome, and the culms are phyllopodic, but develop in the second year; *An analytical table to facilitate the determination of the hitherto observed North American species of the genus Carex. (Ann. New York Lye. Nat. Hist., Vol. 1, p. 70, 1824). | * Ibidem Vol. 1, p. 360, 1828. * Illustrations of the genus Carex Vol. 1, 1858, p. 18, t. 50. Am. J are Scl.—FirtH SEries, Vou. II, No. 11.—-Novemper, 1921. *- 288 T. Holm—Studies wm the Cyperacee. thus they are at the base surrounded by long, withered leaves from the previous year. It is strange that Kiikenthalt attributes an aphyllopodic culm to these species as well as to C. salina, C. subspathacea, etc., which certainly depends on anerror. It is of lower stature than the two former, but of a similar, graceful habit with the | oblong-cylindric to clavate, pistillate spikes drooping on very thin peducles. The scales resemble those of C. crimita, and the arista attains a considerable length; the perigynium is shorter, but broader than the body of the scale, mostly erect, membranaceous, ovate to obovate with a short, emarginate beak; the perigynium has several, but faint nerves; the nut is constricted at the middle. Among twenty-three specimens from Europe and this country the distribution of the sexes was as follows: 14 specimens had 2 staminate spikes. 1 4 iL é¢ a4 3 (74 cé 9 af ‘f) 4 pistiilate 97s 9 4 é6¢ 3 ee a4 5 4 74 2 4 (4 In nineteen of these the pistillate spikes were andro- gynous, and in six of these all the spikes showed this structure. The terminal spike was androgynous in five specimens. Furthermore two pistillate spikes may be developed from the axil of the same bract, which, however, seems to be a rare occurrence. Aperteé. Carex aperta Boott and C. pruinosa Boott are the only members of this section. C. aperta (Figs. 1. and 4). The original diagnosis® reads as follows: ‘‘Spica mascula 1-2 oblongo-cylindrica, acuta, foem. 2-4 oblongis superioribus approximatis sessilibus apice masculis inferiori remota pedicellata saepe toto foeminea, stigm. 2, perig. orbiculatis stipitatis enerviis pellucide punctatis abrupte brevi-rostratis ore A Cyperacez-Caricoidee in Engler’s Das Pflanzenreich Leipzig, 1909, p. le * Flora Boreali-Americana, vol. 2, 1840, p. 218. T. Holm—Studies in the Cyperacee. 289 bidentato squama ferruginea lanceolata acuta latioribus brevior!- busque. Hab. Columbia River. Dougl. Scouler.’’ Howell® calls the species ‘‘bovina’’, and some points in his description deserve mention, viz. ‘‘densely matted and forming extensive meadows of many acres’’. ‘Spikes all peduncled or the upper one sessile, lower more or less cernuous’’. ‘‘On lands that are overflown by the Columbia River’’. The species is aphyllopodic, and the rhizome is densely matted, slightly stoloniferous. With regard to the number of spikes and the distribution of the sexes, we observed in 54 specimens, kindly presented to the writer by Messrs. Louis F. Henderson, James M. Macoun and Wilhelm N. Suksdorf: they were collected in British Columbia, Vancouver Island, Idaho and Washington _ State: | 36 specimens with 1 staminate spike. 15 s he ia spikes. 3 (a 66 3 66 oe 39 a ** 3 pistillate he (74 66 DY 66 66 2 (7 66 4 (4 64 1 if Papert i spike. In fourteen of these some of the pistillate spikes were androgynous: six with two, and eight with one; in four specimens there were a few (1-3) pistillate flowers at the base of the terminal, staminate. The species is known to be abundant at several stations in British Columbia, Vancouver Island, Washington, Oregon and Idaho; it prefers low grounds, but occurs also in the mountains, for instance on Mt. Paddo, where Mr. Suksdorf collected it on borders of ponds at an elevation of 2,000 m. Characteristic of the species are the turgid perigynia with the surface very prominently papillose, by Kiken- thal (1. c. p. 319) interpreted as ‘‘utriculi resinosi,’’ which of course is not correct; all the cells of the epidermis are extended into obtuse, thick-walled papille. Only two nerves, the marginal, are present. The caryopsis is small, obovate, and not constricted. In the material, which has been examined, we have been able to distinguish the forms as follows: °A Flora of Northwest America. Portland, 1903, p. 702. 290 T. Holm—Studies in the Cyperacee. forma 1. concinnula nob. (fig. 2) Culmus.tenuis, 50-80 em. altus, inflorescentia brevis, 6-9 cm. longa. Spicule 2-3 em. longe, graciles, capillari-pedunculate, fere cernue. Washington: Mount Paddo, border of a pond; alt. c. 2,000 m.; collected by Mr. Suksdorf. forma 2. hydroessa nob. (fig. 3.) Culmus 40-60 ecm. altus, strictus, tenuis. Spicule ? minores, valde remote, sessiles vel ima pedunculata. Washington: Bottom-land, Columbia River, after high water; collected by Mr. Suksdorf. | forma 3. mimetica nob. Rhizoma stoloniferum, Culmus 50-60 em. altus, seabberimus. Spicule ? breviores, 4-114 em. longe, nigricantes, sessiles, erecte + remotate, brachtez foliacese, ima spicam masculam valde superans. Habitum Microrhyncharum (e. g. C. aquat.) simulans. Washington: Among bowlders 5 km. west of Bingen; collected by Mr. Suksdorf. C. pruinosa. Boott’s diagnosis’ reads as follows: ‘*Spica mascula 1 subclavata; foemineis 4 cylindricis peduncu- latis evaginatis erectis contiguis superioribus apice masculis inferioribus longissime bracteatis, stigmatibus 2, perigyniis ovatis rostellatis emarginatis obsolete nervosis albo-tuberculatis squama lanceolata mucronata longioribus latioribusque. Hab. In Java, Dr. Horsfield. Culmus tripedalis, glaber; pars spicas gerens biuncialis, scabra. Folia glauca, 114-2 ln. lata, culmo breviora, superne serrato- scabra; ligula obtusa brunnea. Bracteae binae inferiores foliaceae 8-10 poll. longae; reliquae setaceae spicis suis breviores, evagina- tae. Spica mascula 1 poll. longa, 144 lin. lata, basi attenuata, sub- sessilis, squamis ferrugineis. Spicae foemineae 4, superiores plus minus apice masculae, contiguae, 8-14 lin. longae, 2-3 lin. latae ; superior sessilis; squamis brevi-hispido-mucronatis. Peri- eynium | 6/9 lin. latum, ovatum, rostellatum, emarginatum, obso- lete 3-4 nervosum, tuberculis albis minimis conspersum, quasi pruinosum. Achenium orbiculatum, compressum, basi styli aequali terminatum. C. glaucescents Elliott (quae tamen stigmatibus 3 gaudet), habitu et aspectu similis.’’ - ™Caricis species nove, vel minus cognite. (Transact. Linn. Soc., vol. 20, p- 181, 1845-46). T. Holm—Studies in the Cyperacee. 291 In Ill. gen. Carex (1. « vol. 1, 1858, p. 65) Boott regarded the species as being an ally of C. crimta. The species differs from C. aperta by the long-peduncled pis- tillate spikes, by the scales being distinctly mucronate and by the perigynium showing several nerves beside the marginal: but the peculiar, epidermal structure of utriculus is common to both. A very different classification is proposed by Kukenthal (1. c p. 345), who places C. pruimosa in a subsection Praelonge Kiikenth. of the Acute Fr., including Drejer’s Microrrhynche and Aecorastachye. This author con- siders the affinity of C. pruinosa to be with such species as C. torta Boott, C. Sitchensis Prescott, C. phacota Spreng. etc. However, when this author cites Fries as the ~ author of the section Acute we must remember that Fries established this section in the year 1835,° and only for C. acuta L., C. stricta Good. and C. céspitosa L. In the year 1846° Fries classified the Scandinavian Carices in a more elaborate manner, and we see from this that he segregated C. stricta, C. cespitosa and C. turfosa from ‘‘ Phyllopode: Prolize: C. acuta, C. proliaa, ete.’’; according to Fries the Aquatiles, Saline, Rigide and Bicolores were sections dis- tinct from the Prolive and the aphyllopodic Spiculose and Cespitose (C. stricta, etc.). It is therefore abso- lutely incorrect to credit a section ‘‘Acute’’ to Fries, when this author had no intention whatever to make it inelude his other sections, viz. Rigide, Bicolores, ete. As this section Acute is outlined by Kukenthal it can- not possibly be credited to Elias Fries, but to Pastor Kktkenthal himself. We have several years ago'® sug- gested the advisability of independent classification rather than combining the systems proposed by Elias Fries, Kunth. and several other authors, which leads only to misinterpretations, as in the case stated above. Magnifice. To this section we have referred C. magnifica Dew., C. Schottu Dew., and C. lacunarum nob. ® Corpus florarum provinciarum Suecie, p. 191. °Summa Vegetabilium Scandinavie, p. 71. * Greges Caricum, this Journal, vol. 16, p. 449, 1903. 292 T. Holm—Studies wm the Cyperacee. The history of Dewey’s unpublished C. magnifica we have mentioned in some previously published papers,'? stating that C. B. Clarke called our attention to the fact that the species had for many years passed for C. Sitchensis Prescott. C. magnifica is a robust species with the culm reaching a height of about 1.5 m.; the rhizome is stoloniferous, the culms phyllopodic; the latter charac- ter is seldom to be seen in herbarium-specimens, but an excellent specimen collected by Mr. EK. P. Sheldon in — Oregon shows this structure very plainly. The leaves are shorter than the culm, relatively broad, glaucous and thick. Spikes 3-8; the upper was staminate, seldom androgynous, the lower pistillate, mostly androgynous, cylindric, 3-15 em. long., thick, dense-flowered, sessile or nearly so, contiguous, spreading or drooping, often curved. The bracts subtending the pistillate spikes are leaflike, much longer than the inflorescence ; squame of pis- tillate flowers elliptic, acuminate, dark purple with midrib of hghter color; perigynium spreading, coriaceous, obovate, turgid, deep brown, scabrous along the upper margin, terminated by a short emarginate beak. The species is not very variable except with reference to the number of spikes, and, to some extent, the distribution of the sexes, as may be seen from the following table, drawn from 31 specimens: 15 specimens had 2 staminate spikes. ich ¢¢ C6 3 3 6 ce 1 4 ce 2. (4 6 4 (‘m5 4 19aeiiig { Bipistillate, até 8 c¢ 6 Ds (4 6 4 ce 66 4 4 : ce Only in 5 specimens the pistillate spikes were all purely pistillate; in the remaining 26 some or all were androgy- nous; 1n 6 specimens one or two of the lateral male spikes were androgynous, and one specimen had a simple, ter- minal androgynous spike. Some specimens of gigan- tic size were collected by Professor Piper in Alaska (Astoria, June 21st, 1904) ; in these the entire inflorescence measured from 23 to 24 em.; the staminate spikes varied a om 9 to 10 em. in length, and the pistillate from 10 to oem. * This Journal, vol. 17, p. 316, 1904, and vol. 26, p. 486, 1908. T. Holm—Studies in the Cyperacee. 293 Carex magnifica is distributed from Alaska, following the coast, south to California. Carex Schottu Dew. Dewey’s original diagnosis has been cited in our paper dealing with the structure and affinities of some of Dewey’s Carices!? and the species was accepted by C. B. Clarke as identical with C. obnupta Bailey, but distinct from C. Barbare Dew. Nevertheless Kutkenthal (1. ¢. p. 305) refers the species, as a mere synonym, to C. Barbare. Mr. S. B. Parish.* however, holds the opinion that they are distinct. Carex Schottu resembles C. magnifica in many re- spects, but the spikes are longer and more slender, drooping on long peduneles and remote. Carex lacunarum nob.** As may be seen from the diagnosis (1 ¢.) and the figures (1. ec. p. 303) the species is very distinct from the others of this section, especially on account of the lighter color and structure of the perigynium and squama; as a matter of fact the squame of the basal pistillate flowers are very prominently aristate; moreover the perigynia _are appressed, not spreading. | In these sections: Crinite, Aperte and Magnifice the distribution of the sexes thus shows a variation well marked. In C. crinita the terminal spike is some- times gynecandrous, or it consists of a pistillate portion above and below the staminate; or there may be a single pistillate flower subtended by a bract below the terminal, staminate spike; the pistillate are often androgynous. In C. maritima the terminal spike may be androgynous, and in some cases two pistillate spikes may be developed in the axil of the same bract. In C. aperta there may be from one to three pistillate flowers at the base of the terminal, staminate spike. Androgynous staminate spikes eccur in C. magnifica; the pistillate are mostly androgynous; furthermore the terminal may also be “This Journal, vol. 26, p. 478, 1908. ** A preliminary synopsis of the Southern California Cyperacee. (Bull. South. Calif. Acad. Se., 1904, p. 108.) ™ This Journal, vol. 17, p. 316, 1904. ; 294 1. Holm—Studies in the Cyperacee. androgynous. In other words the species of these sections illustrate to some extent the inflorescential structure of the more evolute types of the grex: Ter- narié. In the Saline and Cryptocarpe’ the pistillate _ spikes are often androgynous, and in C. Lyngbyez the ter- minal, staminate spike is sometimes androgynous; other- wise the distribution of the sexes 1s more regular than the sections discussed in the present paper. Clinton, Md., July, 1921. * This Journal, vol. 49, and 50, 1920. J. L. Rich—Stratigraphy of E. New Mexico. 295 | Art. XXI.—The Stratigraphy of Eastern New Meatco— | a Correction; by JoHn L. Riou. In a paper entitled ‘‘ Contributions to the Stratigraphy of Hastern New Mexico’’ which appeared early in 1920,' there are certain statements and correlations which, if allowed to pass unchallenged, are likely to lead to much confusion. During the summer of 1919, the writer spent four months studying the stratigraphy and structure of Guadalupe and adjacent counties. A number of detailed sections were measured, but, unfortunately, they are now ir. the files of an oil company and are inaccessible, so that only generalized descriptions of the sections can be given here. The generalized section for Guadalupe and adjacent counties is: ‘Triassic.—Red and purple shales and sandstones..... 1500’ + Coarse gray sandstone, conglomeratic at base (Sambasivosasamadstome) we leet Os tien ere whe cede. e 50-100’ Triassic or Permian.—Brick red sandstone and red shale, becoming more shaly toward the base..... 150-200’ Permian.—Red, brown and variegated shales and sandstones with much gypsum, anhydrite, and salt (Pecos Valley red beds of Baker and, proba- bly, the Castile Gypsum of other writers). This formation occurs in the form of a wedge, thinning to the northwest, and thickening notably toward NCES OMMCA SE eta. «Oh ont at hoe ATS woe «a's Sia 0 to 1000’ Blue-gray limestone with some gypsum (San An- GUESS aMMINE SOME Er ge kraut cece’ s 6 2 scctinles emgs,s 02s 0) 0 (2) to 300’+ Sandstone, coarse, gray, massive (Glorieta sand- SEOMG ee a Nene e cae ete ce cL ee ae SONS, 300-500’ Salmon pink sandstones and shales, with gypsum @Viero Hormone) pete fais IR EL BATT ee MOO iat Permian (or Pennsylvanian”?).—Dark red sandstones Em@osmalesh GADON est B02 re apie es cia cole =! + 800’ = Baker has confused the Glorieta sandstone in parts of the area with the Santa Rosa sandstone. This has * Baker, C. L., this Journal (4), 49, pp. 99-126, 1920. ? Generally considered to be Permian, but thought by Bose to be Pennsyl- vanian, at least in the lower part. See Bose, Emil, On Ammonoids from the Abo Sandstone of New Mexico and the Age of the Beds which contain them, this Journal (4), 49, pp. 51-60, 1920. 296 J. L. Rich—Stratigraphy of E. New Meaico. led him to assign the Glorieta to the Upper Trias and to correlate the gypsiferous formation above the San Andreas with the Yeso formation whereas, in reality, it is entirely different and much higher. On page 118 he says: ‘“The basal member of the Upper Trias, the Glorieta sandstone, outcrops along the valley of the Pecos from the Glorieta Mesa downstream to somewhere between Puerte de Luna and Fort Sumner. It outcrops at Santa Rosa.’’ This statement shows clearly that Baker thinks the Glorieta sandstone of Glorieta Mesa and the Santa Rosa sandstone are the same, whereas, as will be shown below, they are entirely different. The Santa Rosa sandstone is a very definite unit exposed at Santa Rosa and Puerto de Luna and along the canyon of the Pecos for many miles both above and below those places. From Santa Rosa it may be traced up the valley of the Pecos as a continuous, unbroken, escarpment to the Estaritos Dome, east of Anton Chico, where it forms the rim-rock surrounding the dome. In the center of the dome, about 200 feet below the base of the Santa Rosa sandstone, the San Andreas limestone, 10 to 29 feet thick, is exposed. Beneath the San Andreas on the dome is the Glorieta sandstone in its proper relation and full thickness. The well drilled for oil near the top of the dome started on the top of the Glorieta and penetrated 490 feet of it before entering the salmon-colored sand- stones of the Yeso below. On another dome 5 or 6 miles west of the village of Anton Chico, there are complete exposures of the series from the Glorieta to the Santa Rosa in such relations that there can be no question as to the relative positions of the various formations. Between the latter place and Glorieta Mesa there is a disturbed belt in which there has been some faulting. It is in this belt that Baker appears to have lost his bearings. Hast of this he apparently followed the Santa Rosa sandstone thinking it was the Glorieta. There are many other places in the region between the Pecos and the Belen cut-off of the Santa Fe where the true relation between the Glorieta and the Santa Rosa sandstones can be seen. It may be observed, also, along the Santa Fe Railroad between Las Vegas and Bernal. The confusion of the Santa Rosa with the Glorieta J. L. Rich—Stratigraphy of E. New Meaico. 29% naturally led to the further confusion of the gypsiferous series between the Santa Rosa and the San Andreas with the Yeso. Speaking of the Yeso formation Baker says (pp. IO ET IN: ‘¢ ,.. . and is exposed beneath Upper Trias in the anticlinal axes along the Pecos River from Ribera southwards to beyond Puerto de Luna and in Canon Blanco, a tributary entering the Pecos a few miles below Anton Chico. It is also exposed for many miles in upper Pintada Canon and forms the surface of a large area west of Fort Sumner. Altogether it covers or proba- bly underlies fully half of New Mexico east of. the Rio Grande.’’ In this paragraph it is plain that he has confused the gypsiferous series above the San Andreas with the Yeso. It is the former, not the latter, which ‘‘forms the surface of a large area west of Fort Sumner.’’ The gypsiferous series above the San Andreas wedges out completely in western Guadalupe Co. where the for- mations lap up over the buried granite mountain range which has been revealed by drilling for oil in that region. It appears a few miles to the southeast in Pintada Canyon. From there toward the southeast it thickens notably. The superficial resemblance of this formation -to the gypsiferous part of the Yeso is doubtless partly respon- sible for Baker’s miscorrelation. On page 112, Baker says: ‘““The San Andreas is not known north of the line of the Belen cut-off of the Santa Fe Railroad.’’ As a matter of fact it is well exposed at Vaughn, north of the railroad, from which it may be traced continuously northward for 10 or 12 miles to the foot of the high mesa visible from the railroad and it is at the surface in _ several places on the plain between the mesa and Pastura. It is also exposed on the Hstaritos dome, already referred to, and in the tributaries of Pintada Ganyon north and northeast of Emeino. one of the Upper Triassic rocks, Baker says, p. ‘“West of the Pecos River they extend at least as far south as the Belen cut-off of the Santa Fe Railroad. as 298 J. L. Rich—Stratigraphy of E. New Mexico. This statement, also, is evidently based upon the confusion of the Upper Triassic Santa Rosa sandstone with the Permian Glorieta, for, though the latter extends south to and beyond the railroad, the latter does’ not, except close to or east of the Pecos. Baker’s suggested correlation of the Glorieta with the Shinarump is also based on the erroneous supposition that the Glorieta sandstone of Glorieta Mesa is the same as the sandstone at Santa Rosa. 317 Railway Exchange Bldg., Denver, Colo., June 30, 1921. SCIENTIFIC INTELLIGENCE I. CHEmMIstRY AND Puysics. 1. A New Reaction for Ammonia, and its Application for the Detection of Nitrogen in Organic Substances—C. D. ZENGHELIS has devised a very delicate test for ammonia. His reagent con- sists of a solution containing 20 per cent of silver nitrate and 3 © per cent of commercial formaldehyde solution of 33 to 37 per cent. strength. The reagent should be prepared immediately before use. When some drops of the reagent are placed upon a small watch-glass and this is exposed to the action of ammonia under a crystallizing disk a brilliant mirror of silver is formed upon the surface of the drops of the reagent, or in the case of very small quantities of ammonia, such as 0.000001 or 0.000002¢. brilliant rings of silver are formed around the edges of the drops. In cases where the reagent begins to decompose spontaneously silver is deposited in the form of a powder, and this does not interfere with the reaction, provided that decomposition has not gone too far. The test may be applied to a solution by placing a © small quantity of it in a rather short test-tube, adding a few drops of caustic soda or sodium carbonate solution, covering the mouth of the test-tube with a watch-glass, upon the lower, convex side of which is a drop of the reagent and upon the upper side is a drop of water for the purpose of cooling. Upon warming the liquid in the test-tube until water begins to condense upon the watch.glass, around the drop of the reagent, then discontin- uing the heating, the reaction soon appears in the form of a silver mirror if ammonia is present. It is stated that a distinct Chemistry and Physics. v99 reaction was thus obtained with as little as 0.0000004¢g. of gaseous ammonia, and the reaction is even more delicate than that of Nessler. In order to apply the reaction for detecting nitrogen in organic compounds a small quantity of the substance is mixed in a por- eelain crucible with a mixture of two parts of well-dried soda- lime and one part of finely divided metallic copper, prepared electrolytically. The copper facilitates the formation of ammo- nia from compounds in which the nitrogen is directly combined with oxygen. The crucible is then heated upon a hot plate and the resulting ammonia is detected by means of the reagent on a watch-glass covering the crucible according to the method already mentioned for testing the vapors from a test-tube. It seems probable that the ignition’ with soda-lime and copper could be carried out in the bottom of a test-tube and the tube satisfac- torily made in this way.—Comptes emits; 175, 153 and 308. H. L. W. 2. The Quantitative Separation of Aasonies Antimony and Tin.—F.. L. HAHN and P. Puruippi have adopted for quantitative use a qualitative process that was described about six years ago by the former author. As the method is a simple one and as it varies essentially from the usual processes, it deserves attention. A mixture of the three sulphides is dissolved in the least possible measured quantity of 10 per cent sodium sulphide solution, the same volume of 20 per cent sodium hydroxide is added, the liquid is diluted to 50 or 100 c.c. and strong peroxide (10-30 per cent) 1s sradually added to complete decolorization. The liquid is then heated to boiling, cooled, 1/3 volume of 80 per cent alcohol is added, and after twenty-four hours the precipitated sodium pyro- antimonate is filtered and washed with alcohol of increasing - strength. The precipitate is dissolved in hydrochloric and tar- taric acids in order that antimony may be determined by one of the - usual methods, for instance, as Sb,S, or volumetrically. The fil- trate is evaporated in a porcelain or platinum dish until the alco- hol has been removed, the liquid is diluted to about 300 c¢.c. and the same volume of 50 per cent ammonium nitrate as that of the 20 per cent sodium hydroxide previously used is added, the liquid is boiled until the odor of ammonia has disappeared and the tin precipitate is filtered off and washed with hot, dilute ammonium nitrate solution. The precipitate is ignited and SnO, is weighed. The filtrate is concentrated and ammonium magnesium arsenate is precipitated as usual. This should be dissolved in hydrochloric acid and re-precipitated with ammonia. The authors have carried out as many as fifty-three test- analyses by this method. The results of many of these are given, including those that gave the least accurate results. The agree- ments with the amounts taken are astonishingly close.—Zeitschr. anorgan. u. allgem. Chem., 116, 201. H. L. W. 300 Scientific Intelligence. ~ 3. Chemical Reactions and their Equations; by Inco W. D. HackH. 12mo, pp. 138. Philadelphia, 1921 (P. Blakiston’s Son & Co. Price $1.35 net).—This little book has been prepared for the use of students in connection with the writing of chemical equations. The fundamental ideas about symbols, atoms, mole- cules, ions, formulas, valency, valence numbers, oxidation and reduction, ete., are very clearly presented, and then the principles of chemical reactions and their equations are well discussed. The book presents no less than 446 consecutively numbered equations which cover the various types very fully. Considerable attention is paid to ionic equations, but a great many are given in the molecular form. The book may be regarded as a very useful and satisfactory one for its purpose, but 1t appears that it might be made still better if some discussion were given in regard to reversible reactions, and also if precipitates and volatile products were indicated in some way in the equations, and if reactions of gases or vapors and of fused or ignited substances were distinguished by parenthetical notes from those taking place in solutions. For instance, the equation of an important metallurgical reaction, 2PbO + PbS = 3Pb-+ SO,, which is given without note or comment, might lead the student to suppose incorrectly that this would happen at ordinary temperature. Again, it appears that the equation 2NaCl-+ H,0 = Na,O + 2HCI of a reaction that is familiar in connection with the ‘‘salt- elazing’’ of pottery where the salt is volatilized, should be written with the sign of reversibility and that the high temperature required should be noted. HG 9Wwe 4. Food Products, Their Source, Chemistry and Use; by EK. H. 8. Bamzy. 8vo, pp. 551. Philadelphia, 1921 (P. Blakis- ton’s Son & Co. Price $2.50 net).—This is the second, revised edition of a useful book for students and general readers dealing with a subject of the greatest importance to mankind. A very extensive list of edible products is discussed in connection with their origin and production, their manufacture, composition, food-value, digestibility, adulteration, ete. The book i is supplied with ninety-two appropriate illustrations. It gives a vast amount of valuable and interesting information, not only about the foods commonly used in this country, but also concerning the important products of other parts of the world. The subject of beverages, including water, is well treated, but the discussion of alcoholic drinks has been considerably abbre- viated, in comparison with the previous edition, because the manufacture of these liquors is now of much iess importance than formerly. H. L. W. 5. Discussion on Isotopes——A discussion participated in by Sir Joseph Thomson, Dr. Aston, Professors Soddy, Merton and Lindeman at the March meeting of the Royal Society is inter- Chemistry and Physics. — 301 esting as showing how widely the new interpretations of atomic structure derived from physical experimentation have replaced the earlier conclusions obtained from chemical phenomena alone. The term isotype, 1. e. same place (in the periodic table) was coined by Soddy in 1913 to designate two elements having differ- ent atomic weights but with chemical properties identical, or so closely resembling each other that they have not yet been separ- ated by chemical methods. In contrast to isotypes, the term isobar is used to designate substances of the same atomic, or molecular weight, but having different chemical properties. Lin- deman thinks it doubtful that the properties of isotypes, though ~ indubitably very similar, are exactly identical and hopes to separate them electrolytically if, as seems likely, they have differ- ent migration velocities in solution. On the electron theory the atoms of the isotopes of an element contain an equal number of electrons and the difference in the atomic weight 1s supposed to be due to the simultaneous entry | into the core of the atom, of one or more positive charges and a corresponding number of electrons so that the charge on the core is not affected. Thus one can suppose that an elementary atom of mass m may be changed to one of mass m + 7 by the addition of a positive particle and an electron. If both enter the nucleus an isotope results, for the nuclear charge remains unaltered. If only the positive particle enters the nucleus an atom of the next higher atomic number results.. In cases where both forms of addition give a stable configuration the new elements will be isobars, 1. e. will possess the same atomic weights but have differ- ent chemical properties which are believed to depend upon the number of electrons in the outer layer and its general distance from the center. The work of Aston upon the determination of isotopes by the positive ray spectrograph is characterized by Soddy as one of the most brilliant combinations of mathematical analysis and experi- mental skill this century has produced. The method of focusing positive rays of constant “~ independently of their velocity and ) 7) producing a “‘mass spectrum’’ has been explained in detail by the author in the Philosophical Magazine, 38, 709, 1919, and 39, 611, 1920. Briefly it consists in dispersing a ribbon-like beam of positive rays first by an electric field and then recombining a restricted portion of them by a magnetic field so that they produce a definite linear spot or image on a photographic plate. Where several carriers are present the separation of these lines permits their relative masses to be determined to an accuracy of one part of a thousand. The intensity of the lines also per- mits some estimate of the number of each kind to be made. In this way it has been possible to show that some elementary gases consist of a mixture of two or more isotopes. Neon, for example, 302 — Scentific Intelligence. which by chemical methods shows an atomic weight of 20.200 has been proved: to contain two isotopes having respectively atomic weights of 20.00 and 22.00 in proportion of 90 per cent and 10 per cent with a faint possibility of a third of mass 21. Likewise chlorine which by the method of combining volumes is found to have an atomic weight of 35.46 shows no indication of a line corresponding to this mass but does give definite lines indicating masses 35 and 37. The unquestionable accuracy of its combining weight and the striking whole number masses given on its mass spectrum by its individual particles leaves little doubt that its chemical atomic weight is a statistical average. The investigation which has been extended to more than fifty atomic and molecular weights indicates the very interesting and important result that all these masses as determined by Mr. Aston are integers except in the case of hydrogen. Isotopes have been of use to chemists in various ways as, e. &., the determination of sparingly soluble lead salts has been made with ease. Their use has afforded a test of the Nernst theory of E.M.F. at concentrations completely beyond the range of ordinary methods and has recently given a direct demonstration of the separated existence of ions in an electrolyte-——Proc. Roy. Soc., Sieh eats PAl 2 F. E. B. 6. Wireless Telegraphy and Telephony; by L. B. Turner, pp. xu, 195. Cambridge, 1921 (Cambridge University Press) — The author is a fellow of King’s College and has been connected with the Signals Experimental Establishment of the Royal Engi- neers at Woolwich. This book occupies a position intermediate between the requirement of the student for a treatise on radio- engineering and that of the wireless operator. The need for instance of the electrical engineer who had never studied this particular branch of the subject was in mind in the preparation of what is described as an outline of the frame work of a great and growing subject. It will be understood consequently that the treatment is distinctly topical, rather than compendious, with the discussion full in some cases and scant in others. : After a brief introductory chapter, electromagnetic radiation is taken up but not very satisfactorily presented. The mathe- maties of this and the following chapter is hardly more than the formulation of the physical conditions and a quotation of the results of their mathematical analysis. The reader is either pre- sumed to be familiar with alternating current theory or must consult a treatise on the subject. - Chapter IV gives an interesting account of the production of high frequency currents by spark, alternator, arc, and vacuum tube methods and is followed by a chapter on the detection of these currents. The remainder of the book is occupied with the theory and applications of the thermionic vacuum tube, the new Geology. 303 instrument of such boundless utility that the author compares it to some such fundamental device as the wheel or the lever in mechanics. Chapter VI is devoted to a description of the charac- teristics of the vacuum tube and is followed by a chapter each, occupied with a discussion of the triode, i. e. the three electrode tube, as amplifier, as rectifier, and as oscillation generator. Chap- ter X discusses the use in receiving circuits and amplifiers of the ‘‘retroactive’’ principle by which is meant the way in which the stimulation of the grid by an oscillatory current brings about - an introduction of energy into the oscillatory circuit from the plate battery. Chapter XI gives a good account of wireless telephony. The final chapter is a miscellany touching on such topics as antennae, direction finding, and interference from atmospherics. It should be remarked that the author deals almost exclusively with the British practice and, as was intimated above, the book for the serious student will be chiefly valuable as supplementary reading to other treatises giving interesting sidelights on prin- ciples differently enunciated elsewhere. It seems possible to inundate any discussion of radio-commu- nication with a flood of mathematics which does not always leave the topics any clearer than at the beginning. The author is not open to this criticism for he strives to bring to light some impor- tant fact from his analytical expressions and frequently com- pares different arrangements by means of numerical results. The typography of the book is most pleasing and in addition to the 119 figures in the text twenty-four half tone illustrations ‘ from photographs are introduced to show actual apparatus and installations. One erratum was noticed. The reference in the second equation of Chapter VII should be to p. 96. mH Bs Il. Grotoey. 1. The White Rwer Badlands; by CuropHas C. O’HaArRRA. South Dakota School of Mines, Bull. 13, 181 pp., 96 pls., 75 text figs., 1920.—The president of the South Dakota School of Mines here presents, in more popular form, a much improved re-publi- eation of his ‘‘Badland formations of the Black Hills region’’ of 1910, noticed in this Journal for March, 1911, p. 237. The new edition opens with a glowing pen picture by one of our pioneer geologists, the great John Strong Newberry, who contrasts the present scenery and life of the great West with that of the Ter- tiary. The South Dakota badlands are wonder places for fan- tastic scenery, for visible stratigraphy of fresh-water formations, and above all, as a vast cemetery of antediluvian mammals which have been made known to the scientific fraternity by Hayden, Leidy, Marsh, Hatcher, Scott, and Osborn. The book teems with Am. Jour. Sci1.—FirtH Series, Vou. II. No. 11.—NovemsBer, 1921. 304 Scientific Intelligence. illustrations of the scenery and animals of the White River bad- | lands, and is written, according to the preface, ‘‘in order that the intellectually alert, the indifferent thinker, the old and the young, irrespective of educational advantage or technical training, may have opportunity to get a clearer and more comprehensive idea of this wonderful part of nature’s handiwork.’’ GC. 2. Some Anticlines of Routt County, Colorado; by RB. D. CRAWFORD, K. M. Wiuuson, and V. C. Perini. Colorado Geol. Survey, Bull. 23, 61 pp., 10 figs., 1920:—In this little report is brought together the evidence in regard to the anticlines in Routt County—and there are a number of them—where oil seeps have long been known. The work was done to facilitate the prospect- ing of the petroleum geologists. GS 3. Permian Salt Deposits of the South-central United States; by N. H. Darton. U.S. Geol. Survey, Bull. 715-M, pp. 205-230, pls. 21-24, text figs. 31-40, 1921—This little publication is one of the most striking of the many economic papers issued by the U. S. Geological Survey in recent years. It is now established that the sodium chloride beds of central Kansas are a part of the greatest salt accumulation of the world. These deposits cover an area fully 650 by 150 miles, equalling 100,000 square miles, and up to 700 feet in thickness, in the states of Kansas, western Okla- homa and Texas, and eastern New Mexico. The total quantity of sodium chloride is estimated by Darton at over 30,000 billion tons. Much anhydrite and gypsum is associated, and the whole of this series of salts lies in the lower part of the red beds of the Per- mian. So far, potassium salts in commercial quantities are unknown in this little explored and deeply buried formation, but - there is a possibility and even a probability that such will be discovered. C783) 4. Interrelations of the Fossil Fuels; by JOHN J. STEVENSON. Pp. 458, 1921—Professor Emeritus Stevenson here brings together in book form what he has published under the same title in the Proceedings of the American Philosophical Society during the years 1916-1918 and 1921. To this has been added a table of contents and a good index. He treats of peats and coals, and gives a geologic synopsis of the world’s fossil fuels, the whole testifying to a tremendous amount of labor devoted to bringing together the data presented. We congratulate our distinguished colleague! C..8. 5. Foraminifera of the Philippine and Adjacent Seas; by JOSEPH A. CusHMAN. U.S. Nat. Mus., Bull. 100, vol. 4, 608 pp., 100 pls., 52 text figs., 1921.—In this extensive work are described and figured about 640 species or varieties (47 new) of Foramin- ifera, distributed among 119 genera. They are the result of six hundred dredgings in the Philippine region by the Fisheries steamer ‘‘Albatross,’? from depths ranging down to 1,000 Geology. 305 fathoms. The shallow waters down to 30 fathoms have tropical species in great abundance, and in the deep seas arenaceous forms like those of high latitudes predominate. In this we see that tem- perature controls their distribution, and not depth and pressure. A giant discoidal form is Cycloclypeus carpenteri, growing to 3 inches in diameter. Cae 6. The Direction of Human Evolution; by Epwin GRANT CoNKLIN. Pp. 247, New York (Charles Scribner’s Sons), 1921. —This is certainly a very interesting book on philosophical natur- alism, and because of the easy-flowing language one is swept on through the evidence of what evolution has done for man mor- phologically to the consideration of what in all probability social evolution will do for him. The author first prepares the reader through a discussion of ‘‘Paths and Possibilities of Human Evolution’’ for a better understanding of his views of ‘‘ Evolu- _ tion and Democracy,’’ out of which he believes will eventually come the highest possible happiness for social man, indicated in the concluding section on ‘‘ Evolution and Religion.’’ To the scientist, ‘‘nature is everything that is,’’ and he seeks through observation, experiment, and reason to prove all things and to hold fast to that which is true. Therefore ‘‘the one thing to be desired by church and state, by society and individuals is not perfect truth nor a panacea for all human ills but open- mindedness, sincerity, and sanity.’’ ‘‘The new wine of science is fermenting powerfully in the old bottles of theology.’’ The human body, including the nervous system and the brain, seems to have already attained its limits of evolution, but man, by his increasing power over nature, is actually taking into his evolution the control of his environment. On the other hand, the progressive development of intellectual human society has just begun, for ‘‘in social evolution a new path of progress has been found the end of which no one can foresee.’’ ‘‘The great goal toward which the human race is moving is the rational organiza- tion of society ...a Society of Nations, a Federation of the World.’’ Personal liberty will give way to social organization, to ‘*the freedom of nations and races rather than of individuals, the - self determination of peoples rather than of persons.’’ "*Everywhere the universe is a. cosmos and not a chaos.’’ - Throughout there is design, but we shall never find the explana- tion, for it concerns the origin of things, and finite man, even though his comprehension now extends beyond the stars, can not explain the riddle of the infinite. ‘‘The religion of evolution ... looks forward to unnumbered ages of human progress upon the earth, to ages of better social organization, of increasing specialization and co-operation among individuals and races and nations, to ages of greater justice and peace and altruism. Indeed the religion of evolution is nothing 306 Scientific Intelligence. new, but is the old religion of the world’s greatest leaders and teachers, the religion of Confucius and Plato and Moses and especially of Christ which strives to develop a better and nobler human race and to establish the kingdom of God on the earth.’’ chs 7. Wuossenschaftliche Forschungsberichte. Naturwissenschaft- liche Rethe. Bd. If, Allgemeine Geologie und Stratigraphie; by A. Born. Pp. 145. Dresden and Leipzig (Th. Steinkopff), 1921.—The object of this book is to acquaint the Germans with the essential geologic publications of the world issued during the war years of 1914-1918. The material is arranged according to subjects, each of which is preceded by a general presentation of the views and facts attained by the authors. Cais 8. Mineralogische Tabellen; by P. GrotH and K. Mie.err- NER. 176 pp. Published by R. Oldenbourg, Munich and Berlin, 1921.—The last edition of Groth’s ‘‘ Tabellarische Uebersicht der Mineralien, nach ihren kristallographisch chemischen Beziehun- gen geordnet’’ appeared in 1898. The notable increase in min- eralogical knowledge that has come since that time has made a new edition of this important book very desirable. It has been published with the assistance of Dr. K. Mieleitner, the Curator of the Mineralogical collection in Munich. The form of the book has been changed in this edition but the manner of treatment has remained essentially the same. A table for the determination of the important minerals by means of their physical properties has been added. WwW. E. F. 9. Lehrbuch der Mineralogie; by Gustav TSCHERMAK; 8th edition by FriepRICH BECKE. 751 pp., 977 figs. and 2 colored pls. Published by Alfred Holder, Vienna and Leipzig, 1921. —The first edition of this well known text book was published in 1883, the sixth edition in 1905, the seventh by Dr. Becke in 1914, and after less than seven years this present edition in 1921. The present book differs only in minor details from its immediate predecessor and therefore needs no especial comment. The pub- lication of such a book at the present time under the very great difficulties that must prevail in Austria is especially noteworthy. W. E. FE. III. MisceLLAngovs Screntiric INTELLIGENCE. 1. Elements of Map Projection with Applications to Map and Chart Construction; by CHARLES H. Drrtz, Cartographer, and Oscar S. ApAms, Geodetic Computer. Special Publication No. 68, U. S. Coast and Geodetic Survey. Pp. 163, 74 illustrations, 8 plates, 1921.—This publication is most welcome at this time because of the recent-increase in interest in, and the use of, maps for many purposes. The dependence of the armies in the great war upon accurate maps has led the map makers in and outside Miscellaneous Scientific Intellugence. 307 of the government to give much consideration to the question of projections with a view to constructing maps that will better meet the needs of the public. The present publication is designed to serve as a guide to any- one having a special problem for which accurate maps are neces- sary. It is needless to say that some may wish the projection used on the map to maintain equal areas, that is, that areas on the map will havea definite relation to the corresponding areas on the earth from which the map is projected; others may not be so much interested in the maintenance of a true relation between: the area on the earth and the area on the map, but their problems may involve the question of having the shape of a geographical feature as shown on the maps conform to its shape on the earth’s surface. The first part of the book shows very clearly why the projection of a spherical surface on a plane involves some distortion. This distortion will be in scale or in shape or a combination of both. In the second part of the book are described the various projec- tions In common use. The lst includes the polyconic projection so largely used in the United States; the Bonne projection which has been used a great deal in France; the Lambert conforma] conic projection, which was brought to great prominence because of its very extensive use in the war zone in Europe; and the Mercator projection which is so well known to navigators. Other projections which are somewhat less known than these are also touched upon. These include several projections used to show the whole sphere. There is also described the Grid System or the system of rectangular co-ordinates which is used for military maps in the United States. The book is well illustrated, which makes the text very clear to the reader. This paper should be read and studied by every one who has to deal with matters in which accurate maps play an important part. The authors are to be commended for this important contribution to the literature of geographical science. ; WILLIAM BOWIE. 2. Secrets of Harth and Sea; by Str Ray LANKEsSTER. Pp. xvii, 2483. New York, 1920 (The Macmillan Company ).—For many years the distinguished English zoologist who is the author of this book has contributed popular articles on various scientific topics to the daily or periodical press. Most of them naturally deal with some branch of biology, but others discuss such subjects of chemistry, physics, or geology as may suggest themselves by the news interest of the day. Some twenty-two of these papers have been brought together with more or less extensive revision and additions to form another volume of the author’s ‘‘Science from an Easy Chair’’ and ‘‘ Diversions of a Naturalist.’’ Although widely diverse topics are included, several of the essays deal with early man and his art, and with the derivation of 308 Scientific Intelligence. conventional emblems of ancient and modern peoples, while the other discuss species and hybridization, cross-breeding of races, and curious forms of animal life. The book is of real value not only because of the pleasure and inspiration which the reading of the essays will give, but also because the information contained ‘in them has been subjected to the judicial consideration of one whose wide knowledge and experience enables him to set forth the various phases of the subjects in their true proportions. W. R. C. 3. Observations on the Inving Gastropods of New England; by Epwarp S. Morse. Pp. 1-29; plates 1-9. Peabody Museum. Salem, Mass., 1921.—In spite of the fact that the shells of so many of our mollusks were described a half century or more ago, but little information is as yet available as to the structure and habits of the animals themselves. The observations on the nat- ural history of the species recorded in this paper and especially the life-like drawings of the living animals will therefore be warmly welcomed. They supplement a similar study of the lamellibranchs published a couple of years ago. (See this Jour- nal, 48, 477.) The author also touches a responsive chord in his continued vigorous protest against such needless multipheation of generic names as has been in vogue in recent years. W.R. C. 4. Elements of Bond Investment; by A. M. SaKousxK1. Pp. 158. New York, 1921 (The Ronald Press Company).—In ‘‘ Ele-- ments of Bond Investment’’ Mr. Sakolski has covered in a small volume, easily carried in pocket, a range of topics of remarkable extent. All bear upon the subject of the work, but can only sug- gest the complexity of the factors that go to advise the reader just what are these elements of bond investment. The book describes clearly what a bond is and that is a question probably nine men out of ten could not answer. Everyone has an idea as to what a bond is, until he is asked to tell you and then he usually weakens. The book is valuable as a text book to the entirely ignorant; it can be read profitably by the man who has a hazy idea about bonds and investment; and going still farther, the book is full of orderly information that even the expert investor can cull facts from. It is the work of a practical bond man, not a theorist. Of course to read this book is not to become a competent inves- tor. Men specialize in different kinds of bonds: Government, State, County, Municipal, Railroad, Public Utility and Indus- trial, each with a literature of its own and full of complications. And so the wise investor, be he in some business outside of broker- age, must still advise with the experts before he can safely risk his money. But with ‘‘Hlements of Bond Investment’’ in the back of his head, he is forewarned and, therefore, forearmed. The ° book is readable and covers a large subject with skill and good sound level-headedness. DEAN B. LYMAN. — V W ‘ARDS. Nace Scere Estasuisumenr A Supply-House for Scientific Material. Founded (1862. ee eh ah | Incorporated 1890. ee = tew er our Tkoont eicnlars in the various departments : 2 . Geology: 5-32, Eiesctiptive Catalogue of a Petrographie Col- . lection of American Rocks. J-188 and supplement. tie Price-List of Rocks. ~~ Mineralogy : J-220. Collections. J- 295, Minerals by Weight. . ep J-224, Autumnal Announcements, Paleontology: J-201; Evolution of the Horse. J-199. Palex- _ ozoic index fossils. J-115. Collections of Fossils. Entomology: J- 33. Supplies. J-229. Life Histories. J-230. Live Pupe. ~ Zoology: J-228. 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Sarton= Schiaparelli- Scott - See = Sherrington - Soddy - Starling - Svedberg = Thomson = _ Thorndike-Turner -Volterra ene Wels = ycrnge onathen and more than a hundred others. } ‘* SCHENTIA”’ publishes its articles in the igdruewe of its authors, and joins to the principal text a supplement. containing the French translations of all the articles that are not in French. (Write for a Specimen Number to the General Secretary of ig Reins Milan.) Annual subscription : 40 sh., or 19 dollars post free, Office : 43 Foro Bonaparte, MeARs Italy. Pia Kee Pablishers: ‘WILLIAMS & NORGATE-London; FELIX ALCAN - Paris Ser eee ~ NICOLA ZANICHELLI-Bologna ; ws & . aS CO- Baltimore. nee XVIL _The Ganens Structure of ' Alabandite © (8); oe by R. W.G: Wad orr, Sok abe. Bi | Art. XVI. # ater ‘Cenozoic Mines ‘Betavine from . the Meadow V alley Region, Southeastern Nevada ; Hat | eee Pook ee oy C STOGK St So oe eee Papp ft ee ae See nee XIX.—The Clasfeanns of Igneous Rocks—A Sindy See for Students:;. by L. V: Pirsson,... 25.2 oe Soe pate oe > Anrt.XX; SS aeuies in the Cyperacen; by ‘Vino: Sree Be = eee 6S Carices aeorastachye: Orinitze nob., Apert nob., — ty ee | _-. and Magnifice nob. - (With 8 ee drawn from - a nature by. the author, <. 22.8 oe ees met ee ees Arr. XXI. —The Strati graphy of Eastern New Marien ee: ag Correction; by J: Ls RiGHys 2220 saa ee ere ee “oe gee ey Ee ete ss SCIENTIFIC INTELLIGENCE, pigs, a Aas i Cadaiah y and Physics.—A New Reaction for Ammonia, = its Application | 5 oes for the detection of Nitrogen in Organic Substances, 0. D. ZENGHELIS, 298 —The Quantitative Separation: of Arsenic, Antimony and Tin, F. L. Hann * ie: 2 and P. Purirppr, 299.— Chemical Reactions and their Equations, LW. D7 ee _ Hacky: Food Products, Their Source, Chemistry and. Use, E. Habe Pe 2 BatLey: Discussion of Isotopes, 300. —Wireless Telegraphy and Telephe eg ee ee LL. B. Turner, 302. Sti: Rae AP. _ Geology. —The White River Badlands, Ce O'Hara, 308. Beet: Asteeee of Soma Routt County, Colorado, R. D. ’ORAWFORD, ‘K. M. Wittson, and VY. erent PERINI: Permian Salt’ Deposits of the South-central United States, pe 5 | ; Darton: Inter relations of the Fossil Fuels, J.J. STEVENSON: Foramin of Human Evolution, E. G. CONKLIN, 305. 1 SWiscensetiaftlithio renesinne berichte; Naturwissenschaftliche Reihe, Bd. II, Allcemeine Geologie und — Stratigraphie, A. Born: Mineralogische Tabellen, P. Grora and K bor -LEITNER; Lehrbuch der Mineralogie (G. Tschermak), F. BEcKE, 306. Miscellaneous poten Re, Intelligence. —Elements of a ee with gis hae of New Ragiand EH. S. Morse: Blements of Bond Investment, i SAKOLSKT, 308. . Library, U. S. Nat. Museum. _ Established by BENJAMIN SILLIMAN in 1818. APs abd scx ae THE AMERICAN J OURNAL OF SOLENCE, _Eprron: EDWARD S. DANA. ASSOCIATE EDITORS. Ai a WILLIAM M. DAVIS anv REGINALD A. DALY, Al OF CAMBRIDGE, i | Provmssors HORACE L. WELLS, CHARLES SCHUCHERT, - HERBERT E. GREGORY, WESLEY R. COE ano FREDERICK E. 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This new edition gives, ‘in a ‘practical, convenient way, real’ sore” data of value ‘to all geologists. Part I is a concise summary of the methods — and instr uments most useful in fieldwork, while Part II presents outlines and - schedules" covering special investigations in the several fields of: geology, such as the interpretation of land forms, glaciers and glacial deposits, petrology, lf structural geology, metalliferous and nonmetalliferous deposits, etc, 166 DRECE.. ae by 64. 20 pauls and 2 ae eb ecuns bound, 2 50. 0 postpaid. Mineral Land Surveying z THIRD EDITION, REVISED AND ENLARGED: By JAMES UNDERHILL, ye ALE AE pay eae ee U. Ss. Mineral ‘Sur ala veyor of Colorado, A . x : Describes the methods used at the ‘present time in the surveying of mineral - : Bye lands-in the western portion of the United States. In this edition several || additions have been made, especially of the treatment of the direct solar obser- . vation, and many. changes of value incorporated. ee ; pine 7 23% Eee 41 a Wes figures. oe: bound, ©. 50 postpaid. A Manual -of Determiistive. Mineralogy THIRD, REVISED AND ENLARGED EDITION. By J. VOLNEY LEWIS, Professor of Sagoleny and Mineralogy in Ratgers Pe ~ College, State University of New Jersey. Essentially a new book, rewritten on the basis = many years’ experiences os in teaching, and enlarged to more than double the size of former. editions. 298 pages. 52 by 8. 31 double-page tables, 81 figures. Cloth, ee 00 postpaid Send for copy of these books on Free Mxaminatiod JOHN WILEY & SONS, Inc. 432 Fourth Avenue, New York — w Dit 3- 1994 ... MysevS~ PLATEAE He 1924 Am. Jour. Sci., Vol. ‘u/, X “Wd ‘A ‘BITST ON 980 0d4400 Jo [NYS YIM “Wd “A ‘6TIEL ‘ON “9%—O ‘ed4y09 ‘YSAV]N $2702008 UOpoasody JO UOJo[ays poyunop;—'], VYIY AMERICAN JOURNAL OF SCIENCE Pin SE iL Ess | —__¢e@ Art. XXII.—A Newly Mounted Eporeodon; by Maucoum RutrHerrorpD THorper. With Plate I. [Contributions from the Othniel Charles Marsh Publication Fund, Pea- body Museum, Yale University, New Haven, Connecticut. | In the Marsh Collection are two nearly complete skele- tons of Eporeodon socialis, one of which has been recently restored and mounted. The two specimens are cotypes, designated by Cat. Nos. 13118 and 13119, Y. P. M., and were collected at Scott’s Bluff, Nebraska, by M. H. Clif- ford and A. 8. Shelley on August 17,1874. The skeletons were found very close together, in fact the skull of one was about 3 inches from that of the other and their verte- bral columns were parallel. No. 18119 is now mounted (fig. 1). No. 18118 is a little smaller and of somewhat more slender proportions than the other skeleton. Both animals were fully adult, and while the detection of sex differentiation is extremely difficult if not impossible in this genus, yet it is not unreasonable to suppose that the larger (mounted) skeleton may have been a male and the other a female. The bones, now freed from matrix, are of Upper Oligo- cene (Protoceras beds) age. The preparation and mount- ing were done by Mr. Hugh Gibb under the supervision of the author. After erecting the skeleton, the muscles of the right side of the body, head, and limbs were then modeled by Professor R. 8. Lull over the actual bones. Viewed from the left (fig. 1), practically the entire skele- ton is visible, while the right aspect (fig. 2) shows the complete animal in the flesh. Nearly all of the bones are removable and readily lend:themselves to detailed study. The osteology of this species has been worked out in detail and drawings made of the skull and various bones, for future publication. Am. Jour. Sci.—FirtTH Serigs, Vou, IT, No. 12.—DEcEMBER, 1921. 22 310 M. R. Thorpe—A Newly Mounted Eporeodon. “ad £409 ‘[ ‘SL JO oS1oAOY “YSIVI 82702008 uopoasody Jo uorje10jsey—'g “NIT M. R. Thorpe—A Newly Mounted Eporeodon. 311 Eyoreodon socialis is known up to the present by only three drawings, with no text description. The first refer- ence, in which the species was proposed, was in Professor Marsh’s monograph on the Dinocerata, in 1884.1. The only mention of the species in the text is a line on page 62 where the name H'poreodon alone is used, but this refers to figure 73, page 64, which shows a superior view of the skull of this species, with the brain cast in position. ‘The igs Fic. 3.—Eporeodon socialis Marsh. Left manus. Cotype. After Marsh. xl. Fig. 4.—Hporeodon socialis Marsh. Left pes. Cotype. After Marsh. x 14. skull, however, is incorrectly drawn. On page 187 of the same monograph are two woodcuts, the first, figure 162, of the left manus, and the other, figure 163, of the left pes of the same individual. Both of these latter figures are one third natural size and are reproduced in figures 3 and 4 of the present paper. In the following year,’ Professor Marsh again used the woodcuts of the left pes and manus as figures 128 and 129, without text reference. Until now, therefore, all knowl- edge of this species has been derived from the three above-mentioned woodcuts. Owing to this lack of exact information, it has been erroneously supposed that these cotypes were collected in the John Day basin of Oregon, +O. C. Marsh, U. S. Geol. Survey, Mon. 10. 20. C. Marsh, U.S. Geol. Survey, 5th Ann. Rept., 299, 1885. 312 M. R. Thorpe—A Newly Mounted Eporeodon. and so stated in various faunal lists. The less well pre- served skull and jaws of No. 18119 were replaced in the present mount by the homologous parts of the more com- plete but somewhat smaller cotype, No. 13118. All of the remainder of the mount is of the one individual, the few missing parts being restored in plaster mainly from equivalent parts of the cotype. The vertebral formula is C 7, T 13, L 6, S 4 and Cy 20+. This is not the typical formula found in M ery- coidodon, but it would be very apt to vary as it does in Sus. Undoubtedly there were more than twenty caudals, but this number is all that were collected with the speci- men. ‘The four sacrals and the first sacro-caudal are ankylosed. No complete ribs now pertain to the skeleton, so these have been restored, as well as the superior part of both scapule, part of the pelvis, all of the sternum, and the right metacarpals and phalanges. Nearly all other parts of the skeleton are present in an exceedingly well preserved condition, even to the sesamoid and pisiform bones. So far as the author is aware, this is the first specimen of the genus to be mounted. Skeletons of Merycoidodon, Leptauchenia, Phenacocelus, Promerycocherus, Agri- ocherus, and other allied genera are on exhibition in vari- ous museums in the east, but up to the present none of Eporeodon. The skeleton as mounted is 47.5 inches (1.206 m.) in length and stands 17.75 inches (.452 m.) high at the shoulder. °'W. D. Matthew, Bull. Amer. Mus. Nat. Hist., vol. 12, 64, 1899; U.S. Geol. Survey, Bull. 361, 109, 1909. J. C. Merriam and W. J. Sinclair, Bull. Dept. Geology, Univ. Calif., vol. 5, 187, 1907. C. K. Wentworth—Wedge Work of Pebbles. 318 Arr. XXIII.—A Note on the Wedge. Work of Pebbles; by CHeEster K. WENTWoRTH. The phenomenon here described is one of those very simple processes which are so obvious as ordinarily to be considered unworthy of mention. But one reference to the process is known to the writer’ and it is not so far as he is aware mentioned in any textbook of geology. The wedge work of pebbles first came to the attention of the writer several years since at numerous localities along the gorge of the Potomac River below Great Falls. The action of pebbles in this fashion has since been noticed at other places where the conditions are similar and it will suffice to describe the Great Falls occurrence as typical. Below these falls the Potomac River flows between rock walls which range from 20 to 80 feet in height above low water level. The rock is gneiss which is extensively cut by joints. The rock walls are deeply fissured by differential weathering along lines controlled by the jointing and by the unequal resistance of different zones of the gneiss. On both sides of the present gorge of the river are the rock cut benches of the outer valley on which are strewn sands and gravels in thin, irregular patches. During flood the river rises 20 to 30 feet within the inner gorge and by occupying a number of channels which are dry at other times separates several rock islands from the mainland. In the vicinity of the river the surface of the gneiss is commonly fresh and the rock hard and compact. Within the wedge-shaped open joints are numerous rock fragments, some of which are angular blocks and others well rounded pebbles and cobbles from the gravel. These have lodged in their present positions in part by falling from the level of the rock bench above and in part by deposition during flood stages of the river. The notable feature is that a very large proportion of the pebbles and blocks are wedged tightly in place in the cracks which narrow downward. Pebbles of one or two inches in diameter are more commonly than otherwise held between comparatively smooth rock surfaces so * Wade, A., Some observations on the eastern desert of Egypt, Quart. Jour. Geol. Soc., vol. 67, p. 249. 314. C. K. Wentworth—Wedge Work of Pebbles. tightly that it is impossible to remove them without the use of ahammer. In other words many of the pebbles are much more tightly wedged than would result from the impact of falling alone. In figures 1, 2, and 3 are shown several cracks in which pebbles were tightly lodged. None of the pebbles shown could be removed with the unaided hands. i Geaal The explanation seems to be that the pebbles are wedged in place by the combined action of gravity and the expansion and contraction due to changes in tem- perature. In the case of a crack offering only moderate resistance to further spreading and which does not close again on removal of the force it is apparent that a single C. K. Wentworth—Wedge Work of Pebbles. 315 pebble would ultimately wedge the rock apart. When the pebble is cold and contracted it will fall until its weight is supported. When the air becomes warmer the pebble is heated more rapidly than the general mass of the rock and its expansion exerts pressure on the walls of the crack or fissure. If the pressure is completely met by an elastic yield of the rock mass and the rock recoils OG Ze as the pebble becomes cooler again the latter will not fall and the process will merely be an alternate growth and relief of stress with little or no cumulative rupturing effects. If however the response to expansive stresses is only partially elastic the rock will not recoil completely and the pebble will fall on cooling to a new and more 316 C. K. Wentworth—Wedge Work of Pebbles. effective position and the process will be cumulative in its © results, | Assuming now a perfectly elastic rock mass but several pebbles in place of the one. Let these pebbles be of dif- ferent rocks having different thermal constants and be differently exposed to the air and to the rays of the sun. When periodic temperature changes take place not all Higa. these pebbles will reach their maximum expansion at the same time. Recoil of the rock will follow the progress of the combined stresses rather than that of any one pebble and some pebbles will be free to fall ever so slightly while others hold the load. The pebbles thus act both at the time of greatest heat and similarly at the time of greatest cold to each other as pawls on a ratchet and the process becomes cumulative even with a strictly elastic C. K. Wentworth—Wedge Work of Pebbles. 317 yield in the rock. If the rock yields in part by rupture the effect will be so much the more rapid. The foregoing analysis shows adequately that pebbles can exert cumu- lative stresses in widening cracks and disrupting the rocks. That the pebbles in cracks are usually tightly wedged is proof that they do exert pressure on the walls. It remains to inquire what the quantitative importance of this process is. The factors involved include thermal expansion, thermal conductivity, thermal capacity or specific heat, elasticity, crushing strength, tensile strength and density. It is not essential nor possible here to treat the problem exhaustively and certain approximate assumptions will be made. The following values are taken as sufficiently typical for the common rocks: Coefficient of expansion.... .0000025 per 1 degree F. Compression elasticity..... .00025 per 1000 lbs. to the sq. in. Let a maximum diurnal change of 100 degrees F’. be assumed and let it be considered that this temperature change penetrates only a foot or two. Considering tem- perature changes alone, then, two points on either side of a crack and each several feet within the rock mass will be separated by a distance which remains a constant. Let it further be assumed that the temperature gradients on either side of the crack and extending into the rock be such that the total thermal expansion on both sides is just equal to that wrought on a 4” length by a change of 100 degrees I’. If then a 4” cobble be allowed to fall during the time of minimum temperature into the crack, the total expansion effect of an increase in temperature of 100 degrees will be twice that wrought on the cobble or 2(4” x 100) (.0000025) = .002” The pressure required to produce a .002” diminution of a 4” length will be (x ETE lon) 2000 Iba per sq. t 4" inte, = 8. per sq. In. It is valid to conelude that the pressure exerted by the cobble will equal 2000 times the mean or equivalent cross- sectional area in square inches. This conclusion is based on the assumption that the elastic yielding of the strongly supported regions of contact of the rock walls is negligible. 318 C. K. Wentworth—Wedge Work of Pebbles. If the cobble is taken as a sphere and if the assumption is made that no shearing deformation takes place between successive zones of each segment of the sphere the equi- valent elastic cylinder of the same height will have a diameter of approximately 2.4”. Inasmuch as there will be some deformation of this sort the diameter of the equivalent cylinder will be somewhat less and may be roughly taken as 2” and its end area as 3.14 square inches. This gives a pressure of 6280 pounds exerted by a 4’ cobble under the conditions assumed. Such a pressure is likely to cause local rupturing of the cobble if concen- trated on a very small area at the contact. This will tend to broaden the area of contact to a competent value. With an area of 4 square inch at the contact the pressure computed above is not likely to produce crushing in cobbles of the stronger rocks. From the considerations set forth above it appears that the limit of pressure developed by any single pebble or cobble is that required to compress it by the amount of the thermal expansion caused by the maximum diurnal temperature range. This pressure may be reached only when the area of contact is sufficiently large to transmit it. Most commonly the position reached by the cobble in its fall will be such that there is considerable readjust- ment and local crushing while the first part of the expan- sion takes place. If it be assumed that one half of the expansion takes place before the cobble is adjusted to assume a full load there will remain expansive effect sufficient to produce a pressure on a 4” cobble amounting to over 3000 pounds or 14% tons. It is apparent that the above computations are based on a number of assumptions which are only approximately correct but they serve to show that even after making ample allowance on the conservative side the pressure developed by the expansion of pebbles in cracks is sufficient to produce very considerable disruptive effects. When it is considered that this process is ever active at all temperature ranges it seems that in some situations even where there are freezing temperatures in winter it may be more potent in splitting the rocks than the ice which forms in the cracks, though the writer is by no means disposed to underestimate the effect of the latter. Dale—Drag-Folding in Alabama Marble. 319 Arr. XXIV.—On Concentric Drag-Folding in Alabama Marble; by T. Netson Date. While engaged in collecting material for a U. 8. Geo- logical Survey Bulletin on the marbles of the Southern States, the writer, on Oct. 23d, 1916, noticed in the storage yard of the Moretti-Harrah quarry near Sylacauga, in Talladega County, Alabama, several marble blocks con- No. 1—Block of white marble (6 ft. by 4 ft. 6 inches) from the Moretti- Harrah quarry near Sylacauga, Ala., showing lenses bounded by films of muscovite schist. The drilled face is parallel to the strike of bedding. taining lenses up to 2 ft. in diameter and 6-8 inches in thickness. These lenses were separated from the marble mass by a film of muscovite schist. Two of these blocks with lenses are shown in the reproduced photographs, figs. 1 and 2. Some blocks afforded two vertical sections of the same lens at right angles to one another, thus leav- ing no question as to their being really lenses. 320 Dale—Drag-Folding im Alabama Marble. Dr. William F. Prouty! refers to evidence of ‘‘drag- folding’’ in the marble at Gantts quarry about a mile S.W. of the Moretti-Harrah quarry. Drag-fold- ing differs from plicated bedding in that it consists of the plication of the central part of a bed only, the upper and lower surfaces of which are not at all plicated. It has been explained by Reusch? as being the result of the No. 2. Slab of white marble (12 by 1 ft.), from the same quarry as Fig. 1, showing on the sawn face, which is parallel to the dip direction, lenses bounded by films of muscovite schist and also plicated schist lamine on either side of it. unequal gliding of the upper and lowermost parts of a bed under lateral compression so as to drag the next adjacent parts of the bed in opposite directions and to fold them. Under accompanying pressure in a direction highly inclined to the bed this folding might easily pass into intense plication without affecting the upper and lower surfaces of the bed. The writer has figured such intra-bedding plications in quartzose marble and mica- ceous quartzite in Vermont.® Some of the marble blocks at the Moretti-Harrah quarry showed that the schist lamine were not only 1Prouty, Wm. F., Preliminary Report on the crystalline and other marbles of Alabama, Geol. Survey of Ala., Bull. 18, 1916, pp. 32, 35. * Reusch, Hans R., Die fossilien-fiihrenden krystallinischen Schiefer von Bergen in Norwegen. Authorized German translation by Richard Baldauf, Leipzic, 18835 p. 1lsiios 79: * Structural details in the Green Mountain region and in Eastern New York, U. 8. Geol. Survey XVIth Ann. Report, pt. I, 1896, p. 558, fig. 83; also in U.S. G. S. Bull. 589, The calcite marble and dolomite of Eastern Vermont, 1915, pp. 38, 39. Dale—Drag-Folding in Alabama Marble. 821 intensely plicated between the bedding planes bunt that this plication must have taken place both in the strike and the dip directions, and had resulted in the formation of marble lenses coated with a film of schist. Fig. 1 shows sections of such lenses on the strike face of a block and fig. 2 on the dip face. The latter shows intricate plica- tions of the schist lamine on both sides of the lenses which led up to the formation of the lenses. In order to ascertain whether the micro-texture of the marble near these lenses showed anything abnormal, thin sections were made of pieces from two blocks, one section in the dip direction, the other in the strike direction. Only that in the dip direction from the block represented in fig. 1 showed grain elongation in the direction of the dip. This corroborates evidence from a thin section of the marble at Gantts quarry showing that during metamor- phism there was a powerful pressure along the strike, i. e. about N. 10° E. which is implied in the occurrence of the lenses. Conclusion: The formation of these schist-coated marble lenses involves not only extreme intra-bedding plication (drag-folding) but this must have occurred in rectangular and concentric directions in order to trans- mute plications with longitudinal axes into lenses. Of course the schist laminz are minute layers of clay particles of inorganic sedimentary origin metamorphosed into more or less fibrous muscovite, ete. Sheffield, Mass., Oct. 13, 1921. 322 T. Holum—Studies wm the Cyperacee. Arr. XX V.—Studies im the Cyperacee; by THro. Hom. XXXII. Carices aeorastachye: Phacoteé nob., and Ternarié nob. (With 11 figures drawn from nature by the author.) Phacote. Characteristic of the species of this section is the ter- minal spike being gynaecandrous, even if not constantly so. The lateral spikes are single, not fasciculate; the squamae of the pistillate flowers are mucronate or aristate. The perigynium is membranaceous, ovate to obovate, with a generally short beak, entire to emar- ginate. The section is represented by C. phacota Spreng., C. acisa Boott, C. cernua Boott, C. praelonga C. B. Clarke, C. Prescottiana Boott, and C. Kiotensis Franch. et Sav. They are natives of southern and eastern Asia; C. praelonga inhabits the Himalayas; C. wcisa and C. Kiotensis Japan, while the remaining occur both in the Himalayas and Japan. The accompanying drawings illustrate the structure of the squama of the pistillate flower of C. phacota (fig. 6), and of C. praelonga (fig. 8), taken from about the middle of the spike; at the base of the same spike the mucro becomes an arista. The perigy- nia show only the two marginal nerves (figs. 7 and 9) except in C. Prescottiana, where several fine nerves traverse the perigynium. Ternarie. In this section we meet with species in which the pis- tillate spikes are fasciculate: Carex ternaria Forst., C. tuminensis Kom., C. suddola Boott, C. Darwinu Boott, and C. Arnottiana Nees. The geographical distribution of these species is very scattered: C. ternaria and C. subdola are indigenous to New Zealand; C. tuminensis is a native of Korea; C. Arnottiana of Ceylon, and finally C. Darwini is known from Chile, Argentina and Straits of Magellan. C. ternaria. Boott' describes the species as follows: * Hooker’s Flora Novae Zealandie, 1853, p. 282. TOT Tk Carex ternaria Forst. v. pallida Cheesem.; part of the inflor- escence; natural size. Schematic drawing of a fascicle of spikes of same. Schematic drawing of a fascicle of spikes of Carex cladostachya Wahlenb. For explanation of letters see the text. Fig. 2. MIG os Fig. 4 MiGs .D: Pre, 6. Fig. 7 Fie. 8 Fie. 9. Fie. 10. Ge ale Scale of pistillate flower of C. ternaria v. pallida; enlarged. Utriculus of same; enlarged. Scale of pistillate flower of C. phacota Spreng.; enlarged. Utriculus of same; enlarged. Seale of pistillate flower of praelonga C. B. Clarke; enlarged. Utriculus of same; enlarged. Seale of pistillate flower of C. subdola Boott; enlarged. Utriculus of same; enlarged. 324 T. Holm—Studies in the Cyperacee. ‘