OF THE CLASS MAMMALIA. 31 



The third division of the Gyrencephala enjoy a higher degree of 

 the sense of touch through the greater number and mobility of the 

 digits, and the smaller extent to which they are covered by horny 

 matter. This substance forms a single plate, in the shape of a 

 claw or nafl, which is applied to only one of the surfaces of the 

 extremity of the digit, leaving the other, usually the lower, surface 

 possessed of its tactile faculty ; whence the name Unguiculata, 

 applied to this group, which, however, is more restricted and 

 natural than the group to which Linnaeus extended the term. 

 All the species are ' diphyodont,' and the teeth have a simple in- 

 vestment of enamel. 



The first order, Carnivora, includes the beasts of prey, pro- 

 perly so called. With the exception of a few Seals, the incisors 

 are ^ in number ; the canines j^, always longer than the other 

 teeth, and usually exhibiting a full and perfect development as 

 lethal weapons ; the molars graduate from a trenchant to a tuber- 

 culate form, in proportion as the diet deviates from one strictly of 

 flesh to one of a more miscellaneous kind. The clavicle is rudimental 

 or absent ; the innermost digit is often rudimental or absent ; they 

 have no vesicuke seminales ; the teats are abdominal ; the placenta 

 is zonular. The Carnivora are divided, according to modifications 

 of the limbs, into ' phmigrades,' ' plantigrades,' and ' digitigrades.' 

 In the Phmigrades (Walrus, Seal-tribe) both fore and hind feet 

 are short, and expanded into broad, webbed paddles for swimming, 

 the hinder ones being fettered by continuation of integument to 

 the tail. In the Plantigrades (Bear-tribe) the whole or nearly 

 the whole of the hind foot forms a sole, and rests on the ground. 

 In the Digitigrades (Cat-tribe, Dog-tribe, &c.) only the toes touch 

 the ground, the heel being much raised. 



It has been usual to place the Plantigrades at the head of the 

 Carnivora, apparently because the higher order, Quadrumana, is 

 plantigrade ; but the affinities of the Bear, as evidenced by inter- 

 nal structure, e. g. the renal and genital organs, are closer to the 

 Seal-tribe* ; the broader and flatter pentadactyle foot of the planti- 



them into ' Pachydermes herbivores ' and ' Pachydermes omnivores,' respect- 

 ively equivalent to my Perissodactyla and Artiodactyla, which latter terms M. 

 Pomel adopts. M. Grervais writes : " Les pachydermes omnivores se lient 

 d'une maniere si intime aux Ruminants par les Chevrotains et les Chameaux 

 qu'il est devenu impossible de separer, comme ordre different de celui des Rumi- 

 nants l'ensemble de ces Pachydermes, autrefois confondus avec les Pachydermes 

 herbivores." — Op. cit. Expl. de Planche xxxvi. p. 6, 4to, 1854. 



* ' Catalogue of the Physiological Series,' Mus. R. Coll. of Surgeons, 4to vol 

 ii. 1834, p. 127. Mr. Waterhouse, in noticing the projecting process on the 



