Zoological Society. 408 



not exist, and the pterygoid fossa is nearly in a line with the molar 

 series. The occipital bone presents characters strikingly different 

 from that of the Ruminant ; its surface is flat beneath, with a ridge 

 along the middle ; the condyles are rather distant from each other, 

 their articulating surfaces terminating very abruptly in front ; the 

 paroccipital processes are straight, much prolonged in the genera Sus 

 and Babirussa, placed less laterally than in either the Ruminants or 

 the other division of the Pachydermata, and from each is continued 

 inwards a ridge on about the same level with the base of the occipital 

 bone, and on or near its summit the foramen condyloideum is seen. 

 The space is short between the posterior nares and the auditory 

 bullae, and the origin of the zygomatic process, with its articulating 

 surface, is so much pushed back, that a line drawn across from one 

 to the other would pass right through the bases of the large udder- 

 shaped processes of the tympanic bone ; and the pterygoid processes 

 of the sphenoid have so much lateral expansion, that when the true 

 pterygoid bones have suflicient development to form the inner walls, 

 the fossae are very distinctly marked. For the articulation of the 

 lower jaw there is a transversely elongated surface, concave trans- 

 versely, slightly convex in the antero-posterior direction, which serves 

 alone as a fulcrum for the movements of the jaw, since the space 

 behind it is rugged and does not present the characters of an articu- 

 lating surface. 



But the group at present under consideration seems clearly to 

 admit of separation into two distinct subdivisions, to the first of 

 which, including the genera Sus, Babirussa and Phascochcerus, the 

 foregoing observations are intended more particularly to apply. Of 

 the second, the Peccary and the Hippopotamus present us living ex- 

 amples, and to it the greater number of the extinct genera of artio- 

 dactyle Pachydermata must belong, if the difference which the two 

 subdivisions present in the structure of the molar teeth be found 

 constantly to accompany those of the skull*. 



As so few genera of this second subdivision of the artiodactyle 

 Pachydermata have presented their entire cranium for our examina- 

 tion, it will be better to content ourselves with pointing out the 

 characters in which that of the Peccary, a convenient standard for 

 comparison, differs from the genuine Hogs. 



In this animal the pterygoid bones and processes are pushed nearer 

 the middle, narrowing the aperture of the posterior nares ; and al- 

 though the adult Peccary shows no fissure between the alveoli of the 



* In the very brief notice communicated to the Society last year by Mr. Hodg- 

 son, of a diminutive species of Indian Hog, on which he founds the genus *' Por- 

 cula,^^ it is much to be regretted, that while endeavouring to establish the zoolo- 

 gical position of the genus between the Hogs and the Peccary, and mentioning, 

 as approximating it to the latter, some very trivial external characters, together 

 with the number of molars, which being six in each series, cannot indicate siich 

 an affinity, since the Babirussa, a true Hog, has (in the adult state at least) only 

 five, he has omitted to acquaint us with the structure of those molars, which it 

 might have been expected that a naturalist would have made the subject of par- 

 ticular obsei-vation, and which would very probably have decided the point of 

 affinitv in question. 



26* 



