40^ Zoological Society. 



while in both the divisions of the Pachydermatous order the connec- 

 tion between the palatine and maxillary bones is continued quite to 

 the posterior termination of the latter. In the Ruminant the canal 

 of the posterior nares is of immense depth in the vertical direction, its 

 walls extremely thin, the true pterygoid bones reduced to thin laminae 

 lining the posterior part of the canal, and forming the hamular pro- 

 cesses ; and although in the Camel and Llama, the external and in- 

 ternal processes (of which the former belongs to the sphenoid, while 

 the latter is the true pterygoid bone) being each well- developed at 

 the tip, there is a considerable notch between them, the outer ptery- 

 goid entirely wants that lateral expansion which in animals having a 

 pterygoid fossa forms its outer wall. 



The occipital bone has usually its basal surface flat, marked with 

 eminences, of which different ones are more or less developed in dif- 

 ferent genera. In the Sheep there is a salient one on each side, 

 rendering the surface of the bone between them quite concave ; while 

 in the Camel, the Ox, and the Deer, it is another pair of tubercles 

 that are most developed, being situated close to the condyles, the 

 articulating surfaces of which approach each other more than in the 

 Hogs*, and in the Deer and Camel are even continued on to the 

 tubercles. The paroccipital processes also in Ruminants take their 

 origin more towards the outside than in the Hogs, and the space 

 between this process and the condyle is much more deeply excavated. 

 Each of the three separate types of Ungulata before-mentioned has 

 likewise its distinct form of articulation for the under jaw. That of 

 the Ruminants is a slight convexity, shelving off into a nearly semi- 

 circular concavity behind, thus admirably adapted for the rotatory 

 grinding motion of the under jaw ; this concavity is bounded behind 

 by a ridge, which terminates within in a small process f. 



The following characters are afforded by the foramina : — The fora- 

 men ovale is large, distinct and exposed, completely enclosed by the 

 ali-sphenoid bone ; there is no trace of an ali-sphenoid canal, nor of 

 a distinct canalis caroticus, it being represented merely by a notch 

 in the auditory bulla, having merged into the adjacent Assures. The 

 foramen condyloideum occupies a rather concealed situation, espe- 

 cially in the Deer, where it is quite hidden by the laterally expanding 

 nnterior termination of the occipital condyle : the foramen glenoi- 

 dcum (so named in the second edition of the ' Lecons d'Anatomie 

 Comparee) exists in Ruminants. 



The Hogs and allied genera, constituting the artiodactyle division 

 of the Pachydermata, are constructed upon a second type, also marked 

 by characters seen in the under surface of the skull. The palate is 

 flat and solid, its level much below that of the base of the cranium, 

 extending back quite as far as the extent of the molar series, which 

 throughout its length is closely applied to the walls of the posterior 

 nares ; therefore the large notch so remarkable in the Ruminant does 



* In the Camel they are absolutely in contact below. 



t This process, which is placed more outwardly in the equine type of Pachy- 

 dermata, is in the Rhinoceros much elongated, and even touches the paroccipital, 

 enclosing the meatus auditorius between them. 



