68 
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 lamine 
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 processt. 
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 fissures. The 
foramen condyloideum occupies a rather concealed situation, espe- 
cially in the Deer, where it is quite hidden by the laterally expanding 
anterior termination of the occipital condyle: the foramen glenoi- 
deum (so named in the second edition of the ‘ Lecons d’Anatomie 
Comparée) 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. 
