GENUS HYPSirUYMNUS. 
195 
the teeth just described; and to show the size and form of 
the permanent premolar, it has been necessary to remove a part 
of the bone from the outer side of the jaw. Fig. 2 a, and 
fig. *1 a, represent the fore part of the upper jaw, in which is seen 
the three incisors, followed by the canine, and then by two milk 
teeth, above which milk teeth is the permanent premolar (*), 
which, as it grows, thrusts out the two milk teeth, and assumes 
their place, as in the adult skull, fig. 3 a. 
The letters added to the figures in Plate 8 may here be 
explained:— 
а, is the occipital bone. 
б, the interparietal bone. 
d, the temporal bones. 
c c, the sphenoid. 
d' t expanded portion of the great ala of the sphenoid, 
forming the auditory bulla. 
e e , parietal bones. 
f palatine bones. 
/^posterior palatine openings. 
9 9 , frontal bones. 
h /#, lachrymal bones, 
t f, malar bones. 
k k y nasal bones. 
/ /, maxillary bones. 
/ I *, palatal portion of the maxillary bones. 
m m, intermaxillary bones. 
in. incisor teeth. 
ca . canine. 
p-m. premolar. 
Of the lower jaw (figs. 2 o, and 3 b.) 
A, is the horizontal branch, or ramus. 
B, the ascending ramus. 
1, the coronoid process. 
2, the condyloid process. 
3, the angular process. 
*> the incisor tooth. 
p-m, the premolar. 
OT » four true molar teeth. 
