RHINOCEROS. 89 



exists ill Eliinoceros indtcus, is open at tlie bottom. The process is strong and is 

 bent forward at its apex, which is tuberous and extends nearly as far downward as 

 the post-glenoid tubercle, from which it is about five lines distant. 



The pars petrosa is quite small. It appears at the bottom of the arch between 

 the post-glenoid and para-mastoid processes, as a V-shaped body, bent forward at 

 its lower part by the base of the styloid process. 



The remaining portion of the latter, in the specimen, is a stout cylinder clasped 

 antero-internally by the os petrosa. 



Between the bottom of the styloid and para-mastoid processes is the stylo- 

 mastoid foramen. 



The foramen lacerum is a very large reniform vacuity, being about an inch in 

 diameter antero-posteriorly, and about four lines transversely. 



In advance of the latter a few lines is a distinct foramen ovale, and a short 

 distance antero-internal to this is a round foramen, conducting into the homologue 

 of the foramina rotundum and spheno-orbitale. 



The latter opens at the bottom of the orbit just internal to a pointed process 

 arising from the conjunction of three ridges ; one of which comes from the margin 

 of the foramen, the other from above the position of the optic foramen, and the 

 third constitutes the boundary of origin between the temporal and external ptery- 

 goid surfaces. 



The optic foramen is placed about an inch in advance of the spheno-orbitale. 



The glenoid articulation is more concave than in Rhinoceros indicus, and that 

 portion of its surface situated on the anterior part of the root of the zygomatic 

 process presents more backward and outward. 



The post-glenoid tubercle, compared with that of Rhinoceros indicus, is relatively 

 short; at its outer margin being ten lines in length, and it projects only two lines 

 below the mastoid process. What it loses in length it gains in robustness and 

 breadth ; and its outer side is rough, and the apex truncated. Posteriorly it is 

 perforated by a vertical foramen. 



The interpalatine notch extends forward as far as the posterior third of the 

 penultimate molar tooth. 



The hard palate is strongly arched, though not so much as in Rhinoceros occi- 

 dentalis, and it also differs from that of the latter in being relatively broader, and 

 less convergent at the alveolar margin anteriorly. 



Inferior Maxilla. — (PI. XIV. 2.) The body of the lower jaw externally is ver- 

 tically convex, and anteriorly is more convergent than in Rhinoceros indicus. Its 

 depth below the posterior molar tooth is about twenty lines ; below the first molar, 

 fifteen lines. The base is rounded, and is about as convex antero-posteriorly as in 

 the last mentioned species. 



In the specimen under investigation, the symphysis is broken off a few lines in 

 advance of the molars, and it there presents a crescentic surface only ten lines 

 broad and six deep, indicating the inferior incisor teeth to be of small size in this 

 species. Upon each side of the broken surface, about three-fourths of an inch from 

 the position of the first molar teeth, there remains the end of the fang of the 

 external incisors. 



