CHAP. XIII DOG’S SKULL 387 
SuB-ORDER 1. FISSIPEDIA. 
A very marked feature of the terrestrial Carnivora is to be 
found in the structure of the teeth. The incisors are nearly 
always six, and are somewhat feebly developed in many cases. The 
Fic. 190.—Under surface of the 
cranium of a Dog. x4. apf, 
Anterior palatine foramen ; AS, 
alisphenoid ; as, posterior open- 
ing of alisphenoid canal; BO, 
basioccipital ; BS, basisphenoid ; 
cf, condylar foramen ; eam, ex- 
ternal auditory meatus ; HzO, 
exoccipital ; lm, jlp, foramen 
lacerum medium and posterius ; 
Jm, foramen magnum ; fo, fora- 
men ovale; £7, frontal; jr, 
foramen rotundum ; gf, glenoid 
fossa ; gp, post-glenoid process ; 
Ma, malar; Mx, maxilla; oc, 
occipital condyle ; op, optic fora- 
men; Per, mastoid portion of 
periotie ; pg, post-glenoid fora- 
men; P/, palatine ; PMz, pre- 
maxilla; pp, paroccipital pro- 
cess ; ppf, posterior palatine 
foramen ; PS, presphenoid; /2, 
pterygoid ; sf, sphenoidal fissure 
or foramen lacerum anterius ; = 
sm, stylomastoid foramen ; SO 
supraoccipital ; Sy, zygomati 
process of squamosal ; 7, tym- 
panic bulla; Vo, vomer. (From 
Flower’s Osteology.) 
canines are almost invariably very large strong teeth, and are 
always present. In some. of the extinct Cats they reached 
enormous dimensions. The number of cheek teeth is not always 
identical ; but the last premolar in the upper jaw and the first true 
molar in the lower jaw, known as the “ carnassial” or “ sectorial ” 
teeth, mark a difference in structure between the anterior and 
the posterior crushing teeth; those in front of the carnassial 
tooth have cutting edges, and are often merely small, conical 
teeth ; those behind have broader crowns and are tuberculate ; 
those of simpler forms often trituberculate ; those of others 
