1881.] 189 [Cope. 



is a distinct ciugulum which is only wanting from tlie inner base of the 

 crown. The fourtli superior premolar has a trilobate outline of the base 

 of the crown, the base of the inner lobe being contracted where it joins 

 the external part of the crown. The internal tubercle is conic, with a 

 prolongation outwards and forwards. Intermediate tubercle not distinct. 

 External, anterior, and posterior cingula. 



In the hiferior true molars the external tubercles wear into crescents. 

 The crowns increase in size posteriorly, which is the reverse of the order 

 of enlargement in some of the other species of the genus. The flftb 

 tubercle of the last molar is rather small, but is well distinguished from 

 the other cusps. The internal median cusp is small, the external median, 

 large. The premolars are not so much larger than the true molars in this 

 as in the typical species of the genus. The second and third are more 

 elongate on the base than the fourth. The latter is also less compressed 

 than those that precede it. It has a short wide heel, and a small anterior 

 basal tubercle. In the second and third premolars the posterior edge of 

 the principal cusp is sharp, and descends gradually to the posterior base of 

 the crown. Both have small acute anterior basal tubercles. The first 

 inferior premolar is one-rooted, and has a simple crown directed some- 

 what forwards. It is separated from the second hj a short space. The 

 teeth anterior to this point are lost. 



Measurements. M. 



Length posterior four superior molars 0182 



Diameters P-m. IV f anteroposterior 0040 



>. transverse 0042 



Diameters M. II j anteroposterior 0043 



I transverse 0060 



Diameters M. Ill | anteroposterior 0040 



< transverse 0060 



Length of inferior molars 0330 



" " premolars 0192 



P-m. Ill 0055 



" P-m. IV 0045 



Diameters M. I. -[ anteroposterior 0040 



I transverse 0033 ■ 



Diameters M. Ill [ anteroposterior 0052 



t^ transverse 0040 



Depth of ramus at P-m. 1 0047 



M. II 0090 



Length of astragalus -.0102 



Width of trochlea behind 0048 



Diameters of cuboid jl«"Sth 0070 



I width of middle 0040 



MlOCL^NUS ETSAGICUS, Sp. nOV. 



This, the largest species of the genus, is represented by the two rami of 



