56o 



MANUAL OF ZOOLOGY. 



place being taken by a callous pad of hardened gum, against 

 which the lower incisors impinge (fig. 218). There are also 

 no upper canine teeth, and the only teeth in the upper jaw 

 are six molars on each side'. In the front of the lower jaw is 

 a continuous and uninterrupted series of eight teeth, of which 

 the central six are incisors, and the two outer ones are re- 

 garded by Owen as being canines. Upon this view, canine 

 teeth are present in the lower jaw of the typical Ruminants, 

 and they are only remarkable for being placed in the same 

 series as the incisors, which they altogether resemble in shape, 

 size, and direction. Behind this continuous series of eight 



Fig. 218. — Skull of a hornless Sheep (after Owen). / Incisors; c Canines; 

 .- m. Molars and Fr^emolars. 



teeth in the lower jaw, there is a vacant space, which is fol- 

 lowed behind by six molars on each side. The prsemolars 

 and molars have their grinding-surfaces marked with two 

 double crescents, the convexities of which are turned inwards 

 in the upper, and outwards in the lower teeth. 

 The dental formula, then, for' a typical Ruminant animal, is — 



3—3' 



0—0 ^ 3—3 

 c -^—^ ; pm 



3—3 

 3-3. -^=32. 



The departures from this typical formula occur in the Camelida 

 and in some of the Deer. Most of the Deer conform in their 

 dentition to the above formula, but a few forms (e.g., the 



