TEETH OF CETACEA % 107 



teeth, immediately following the incisors, are called cuspi- 

 date, or canine, teeth, from their being particularly conspi- 

 cuous in dogs; as they are, indeed, in all the purely carnivo- 

 rous tribes. In the larger beasts of prey, as the lion and the 

 tiger, they become most powerful weapons of destruction: 

 in the boar they are likewise of great size, and constitute the 

 tusks of the animal. All the teeth that are placed farther 

 back in the jaw are designated by the general name of molar 

 teeth, or grinders^ but it is a class which includes several 

 different forms of teeth. Those teeth which are situated 

 next to the canine teeth, partake oT the conical form, having 

 pointed eminences; these are called the false molar teeth, 

 and, also, from their having generally two points, or cusps, 

 the bicuspidate teeth. The posterior molar teeth are diffe- 

 rently shaped in carnivorous animals, for they are raised into 

 sharp and often serrated ridges, having many of the proper- 

 ties of cutting teeth. In insectivorous and frugivorous ani- 

 mals their surface presents prominent tubercles, either point- 

 ed or rounded, for pounding the food; while in quadrupeds 

 that feed on grass or grain they are flat and rough, for the 

 purpose simply of grinding. 



The apparatus for giving motion to the jaws is likewise 

 varied according to the particular movements required to act 

 upon the food in the different tribes. The articulation of the 

 lower jaw with the temporal bone of the skull, approaches 

 to a hinge joint; but considerable latitude is allowed to its 

 motions by the interposition of a moveable cartilage between 

 the two surfaces of articulation, a contrivance admirably an- 

 swering the intended purpose. Hence, in addition to the 

 principal movements of opening and shutting, which are 

 made in a vertical direction, the lower jaw has also some de- 

 gree of mobility in a horizontal or lateral direction, and is 

 likewise capable of being moved backwards or forwards, to 

 a certain extent. The muscles which effect the closing of 

 the jaw are principally the temporal and the masseter mus- 

 cles; the former occupying the hollow of the temples, the 

 latter connecting the lower angle of the jaw with the zygo- 



