124 



which, considerably worn, are represented in Fig. 4, Plate XXVIT, magnitied 

 eight diameters. 



The portion of jaw is of moderate depth and stont in proportion. The 

 base is thick and rounded. The masseteric depression is well marked, and is 

 defined at its lower part in front by a strong ridge descending from the fore 

 part of the coronoid process and ending in a conspicnous angular tubercle. 



The {eeth resemble most nearly tliose of Microsyops. They are inserted 

 with a pair of flings; but in the last molar the posterior fang is a connate pair 

 extended backward. 



The crown of the antepenultimate molar is quadrate with rounded corners, 

 and is composed of four lobes. The postero-external lobe is largest, and is 

 crescentoid conical. The postero-internal lobe is smallest and conical, and is 

 joined at the summit by the back arm of the postero-external lobe. The 

 anterior pair of lobes are connate, and are joined about their middle by the 

 fore arm of the postero-external lobe. A deep angular valley occupies the 

 inner part of the crown between the anterior and postero-internal lobes, and 

 bounded externally by the postero-external lobe. A basal ridge incloses the 

 outer part of the crown, but is interrupted in the most prominent part of the 

 postero-external lobe. 



The crown of the last molar, at its anterior two divisions, is composed on 

 the same plan as that of the molar in advance, but it is prolonged backward 

 so as to form an additional lobe. 



The measurements of the specimen are as follows: 



Lines. 



Dei)tli of lower jaw below tlie last molar 2.1 



Space occupied by the last two molars '. 2. 4 



Breadth of second molar 1.2 



Breadth of last molar . . ^ 1. 4 



The genus I have named in commemoration of Washakie, chief of the 

 Shoshone Indians, with whom I had the pleasure of meeting during my visit 

 to Fort Bridger. He has always been distinguished for his high characler, 

 and for his friendliness to the white race. 



ELOTHERIUM. 



In tlie American Journal of Science of 1871 Professor Marsli has described 

 a molar tooth, from Hejiry's Fork of Green River, which he attributes to a 

 suilline pacliyderm with the name of Elotherium lentus. The specimen, he 



