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 



FIG. 190. Under surface of the 

 cranium of a Dog. x . upf, 

 Anterior palatine foramen ; AS, 

 alisphenoid ; as, posterior open- 

 ing of alisphenoid canal ; BO, 

 basioccipital ; BS, basisphenoid ; 

 cf, condylar foramen ; earn, ex- 

 ternal auditory meatus ; ExO, 

 exoccipital ; Jim, Jtp, foramen 

 lacerum medium and posterius ; 

 ./>, foramen magnum ; fo, fora- 

 men ovale ; Fr t frontal ; fr, 

 foramen rotundum ; gf, glenoid 

 fossa ; gp, post-glenoid process ; 

 Ma, malar ; MX, maxilla ; oc, 

 occipital condyle ; op, optic fora- 

 men ; Per, mnstoid portion of 

 periotic ; pgf, post-glenoid fora- 

 men ; PI, palatine ; PMx, pre- 

 niaxilla ; pp, paroccipital pro- 

 cess ; ppf, posterior palatine 

 foramen ; PS, presphenoid ; Pt, 

 pterygoid ; sf, sphenoidal fissure 

 or foramen lacerum auterius ; 

 sm, stylomastoid foramen ; SO, 

 supraoccipital ; Sq, zygomatic 

 process of squamosal ; Ty, tym- 

 panic bulla ; Vo, vomer. (From 

 Flower's Osteology.) 



apf 



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 



