194 



FAUNA ANTIQUA SIVALENSIS. 



The antepeniiltimate premolar of the Sewalik fossil is 

 somewhat difierent from the two others, being much smaller, 

 and contracting upwards into a trenchant edge. The cusp is 

 connected by a transverse ridge with the mam ridge of the 

 crown, and the basal ridge is reduced to a small mammilla in 

 front of the ciisp. 



Plate XYII. fig. 2 represents the outside of the right upper 

 jaw, comprising the four back molars, and is an exact coun- 

 terpart, so far as it goes, of the left upper jaw. 



There is little else shown by this specimen than what re- 

 gards the teeth. The muzzle appears to have fined off 

 rather abruptly in front of the malar protuberances, and 

 the orbit to have been advanced more forward on the face, 

 and to have been more depressed below the brow than in 

 A. commune.^ The upper orifice of the sub-orbital canal is 

 seen opening behind the anterior angle of the orbit, the floor 

 of which appears to have extended behind the post-orbital 

 j)rocesses. 



The dimensions, a's compared with those of A. commune, 

 and Chalicotherium Goldfussi, are as follows : — 



Length of the series of 6 molars 



Ditto 3 true molars 



Ditto 3 premolars . 



Length of the last true molar . 



Width of ditto 



Length of the penultimate true molar 



Width of ditto 



Length of the antepenultimate true molar 



AVidth of ditto 



Length of the last premolar 



Width of ditto 



Length of the penultimate premolar . 



Width of ditto 



Length of the antepenultimate premolar 



Width of ditto 



Height of the last molar . 



These measurements show the Sewalik species to have been 

 larger than A. comm,une, and smaller than Chalicotherium 

 Goldfussi. One of the most striking points in which it 

 differs from the two latter terms of comparison is in the 

 dimensions of its back molar, which, with the same amount 

 of wear, is about half an inch higher than in A. commune, 

 and in this respect considerably exceeds even the longer and 

 wider tooth of the Chalicotherium. 



' See Ossemens Fossiles, tom. iii. tab. 57. fig. 1. 



