60 Classification of the Mammalia. 



Seal-tribe ; the broader and flatter pentadactyle foot of the plan- 

 tigrade is nearer in form to the flipper of the Seal than is the 

 more perfect digitigrade, retractile clawed, long and narrow hind 

 foot of the feline quadruped, which is the highest and most typi- 

 cal of the Carnivora. 



The next perfection which is superinduced upon the unguiculate 

 limb is such a modification in the size, shape, position, and direc- 

 tion of the innermost digit, that it can be opposed, as a thumb, 

 to the other digits, thus constituting what is properly termed a 

 ' hand.' Those Unguiculates which have both fore and hind 

 limbs so modified, or at least the hind limbs, form the order Qua- 



DEUMANA. 



Archencephala. 



The structural modifications in the genus Homo, — the sole re- 

 presentative of the Archencephala, — more especially of the lower 

 limb, by which the erect stature and bipedal gait are maintained, 

 are such as to claim for Man ordinal distinction on merely exter- 

 nal zoological characters. But as I have already argued, his 

 psychological powers, in association with his extraordinarily de- 

 veloped brain, entitle the group which he represents to equivalent 

 rank with the other primary divisions of the class Mammalia 

 founded on cerebral characters. In this primary group Man 

 forms but one genus, Homo, and that genus but one order, called 

 Bimana, on account of the opposable thumb being restricted to 

 the upper pair of limbs. The testes are scrotal ; their serous 

 sac does not communicate with the abdomen ; they are associated 

 with vesicular and prostatic glands. The mammae are pectoral- 

 The placenta is a single, subcircular, cellulo-vascular, discoid body. 



Man has only a partial covering of hair, which is not merely 

 protective of the head, but is ornamental and distinctive of sex. 

 The dentition of the genus Homo is reduced to thirty-two teeth 

 by the suppression of the outer incisor and the first two premolars 

 of the typical series on each side of both jaws, the dental formula 



• 2 1 1 1 2 2 3 3 r>-» 



*• 2=5> c - r—n P- 2 -=3 m. jns =32. 



All the teeth are of equal length, and there is no break in the 

 series ; they are subservient in Man not only to alimentation, but 

 to beauty and to speech. 



