DAKOTA AND NEBRASKA. 175 



From the various collections of fossils subsequently brought from the Mauvaises 

 Terres of White River, and submitted to my inspection, I have had the opportunity 

 of examining a number of specimens pertaining to different individuals of several 

 species oi Hlotherium, sufficient altogether to give us a knowledge of nearly the whole 

 skull, including the dentition. Of other parts of the skeleton only a few fragments 

 have been identified. 



From the many fragments of skulls of Elotherium I have attempted the restoration 

 of a complete one, as represented in plate XVI. Though perhaps not entirely 

 accurate in all its proportions, as the specimens vary considerably in size and exact 

 details of form, apparently from differences of age, sex, and individual peculiarity, yet 

 the restoration gives a fair idea of the form of the skull, and the parts, as taken from 

 different specimens, are anatomically correct. 



In comparison with the figures and description of the dentition of the European 

 Elotherium, as given in Gervais' Pal^ontologie Frangaise and Pictet's Traits de 

 Pal^ontologie, that of the American Elotherium appears to agree in all essential 

 characters. 



Elotherium Mortoni. 



Of this species I have had the opportunity of examining portions of the skull of 

 about fifteen different individuals. One of the best preserved specimens consists of 

 the greater part of a skull of an animal which had not yet reached adult age, and 

 which is represented in plates viii, ix, figures 1, 2, of the Ancient Fauna of Nebraska. 



The restored skull of E. Morto)ii is represented in plate XVI, about two-thirds the 

 diameter of nature. The parts a, b, c are derived from the particular specimen above 

 indicated, except portions of the nasal and frontal on the part h. The anterior 

 extremity of the face, marked d, is derived from a well-preserved adult specimen, 

 except the nasal bone, which is introduced from another individual. The portions of 

 the lower jaw marked e,f, are derived mainly from a fourth individual, but perfected 

 from a fifth one. 



The skull of E. Mortoni in its adult condition was about the size of that of the 

 Wild Boar, and was about a third less in size than that of the Entelodon magnum, 

 Aymard, or Elotherium Aymardi of Pomel. 



In a side view the skull bears some resemblance to that of the Hog, but it is less 

 elevated posteriorly, so that its upper part does not slant so much. The cranium is 

 longer and lower, and is surmounted by a high sagittal crest. The temporal fossa is 

 far more capacious, and the zygomatic arches extend more outwardly. The orbit is 

 more advanced in position, and it has a complete bony rim and a more forward 

 direction The side of the face is cylindroid, and converges I'egularly to the snout. 

 The nasals project but slightly. The ascending ramus of the lower jaw is short, and 



