538 THE WASATCH FAUNA. 



Among the large Coryphodontes from the Big Horn Basin two sizes 

 may be distinguished, a larger and a smaller. The latter usually have the 

 posterior crest of the posterior inferior true molar transverse, and there is 

 no interior crest or tubercle in front of it. Those I have referred to under 

 the head of C. latipes, and the subject of Plate XLVI represents tliem, ex- 

 cepting only the spaces between the premolar teeth. But some of them 

 display a more or less distinct trace of the internal crest, and in one speci- 

 men it is present on one side and not on the other. The larger specimens 

 always possess the internal tubercle, and I refer these to the C. anax. The 

 tubercle and posterior crest vary somewhat in proportions. In two speci- 

 mens the latter is very short and oblique, its internal extremity having the 

 position of the heel of a five-lobed molar; in three specimens it is longer 

 and more normal. This is the character of the Conjpliodon Jobatus. In 

 such specimens the internal lobe is nearer the extremity of the transverse 

 iii'est, and the posterior border of the tooth is not angulate backwards. 

 The specimens of this kind are as large as those typical of C. anax, and 

 perhaps should be regarded as belonging to the C. lobatus. Owing to the 

 want of superior molars, I cannot ascertain the full characters of the latter 

 species. 



A partially complete skeleton of a true C. anax includes the following 

 bones: most of the mandible with several, including the last, molars; a few 

 vertebrae, including axis; glenoid cavity of scapula; humerus and ulnae 

 ■complete, with parts of radius, parts of carpus; femur and tibia complete, 

 parts of fibula, carpus and phalanges. 



The ramus of the lower jaw is considerably deeper than that of the C. 

 latipes (cfr. PI. XLVI), and its inferior border rises backwards just below 

 the posterior border of the last inferior molar. The symphysis extends to 

 below the posterior border of the third inferior premolar, and the gutter for 

 the tongue is quite deep. The surface spreads out to the bases of the ca- 

 nines and incisors, losing its concavity at the median border. Tlie 

 mental foramen is large and is situated below the first premolar on one side, 

 and is double, and is below the second premolar on the other. The second 

 true molar has the usual characteristic form of the genus, including a narrow 

 posterior basal cingulum. Tlie last molar is like that of other species (ex- 

 cepting the C. curvicristis) anteriorly, but the posterior crest forms a rect- 



