E. L. Troxell — Entelodonts in Marsh Collection. 247 



Osborn, H. F. 1910. The age of mammals. New York. 



Peterson, O. A. 1909. A revision of the Entelodontidse. Mem. Carnegie 



Mus., 4, No. 3, 41-156. 

 Pictet, F.-J. 1853. Traite de Paleontologie, 2d ed., 1, 328; and atlas, pi. 



13, figs. 8, 9. Paris. 

 Eoger, Otto. 1887. Verzeichniss der bisher bekannten fossilen Saugethiere. 



Naturwiss. Ver. f. Schwaben u. Neuburg in Augsburg, 29. Bericht, 



92-93. 

 Scott, W. B. 1898. The osteology of Elotherium. Trans. Amer. Philos. 



Soc, 19, 273-324. 

 — 1913. A history of land mammals in the western hemisphere. New 



York. 

 Sinclair, W. J. 1905. New or imperfectly known rodents and ungulates 



from the John Day series. Univ. Calif., Bull. Dept. Geology, 4, 125- 



143. 

 Entelodon calkinsi, sp. nov. 

 Tournouer, Eaoul. 1869. Sur Page geologique des "mOllasses de 



l'Agenais, " a propos de la decouverte de nouveaux debris &' Elotherium 



magnum et de divers autres mammiferes dans les terrains tertiaires 



d'eau douce du departement de Lot et Garonne. Paris, Bull. Soc. 



Geol., 26, 983-1023. 

 Woodward, A. S. 1904. A guide to the fossil mammals and birds in the 



British Museum (Natural History). London. 

 Woodward, A. S., and Sherborn, C. D. 1890. A catalogue of British 



fossil Vertebrata, p. 345. London. 

 Woodward, Henry. 1890. A guide to the exhibition galleries of the De- 

 partment of Geology and Palaeontology in the British Museum (Natural 



History), Pt. 1, Fossil mammals and birds, pp. 44-45. London. 

 Wortman, J. L. 1893. On the divisions of the White Eiver, or Lower 



Miocene, of Dakota. Bull. Amer. Mus. Nat. Hist., 5, 102-103. 

 Elotherium in Oreodon and Protoceras beds. 



PART I. MORPHOLOGY AND TAXONOMY. 



Inteoduction. 



Purpose of the present paper. — The development of our 

 knowledge of the group of giant pigs called entelodonts 

 has been so well given, especially by Scott (1898) and by 

 Peterson (1909), that it is not worth while for us to repeat 

 its general history, but in the great amount of material in 

 the Yale Museum there are several specimens of unusual 

 importance, some of which are entirely unknown to the 

 scientific public, and some are but imperfectly known or 

 have even been misrepresented in the literature, and so it 

 seems necessary to go over this phase of the work again. 

 There is a double purpose in presenting a paper on this 

 material, namely, that of increasing the value of the speci- 

 mens themselves, forming as they do a part of the inter- 

 esting collection which Professor Marsh brought together 



