88 



On the Classification of Animals 



because of the high degree of cephalic concentration ; while in the 

 Schizopods referred to above, and in the Limulus and many other 

 inferior Crustaceans, the same deficiency comes from weakness of 

 life-system or decephalization. 



(2.) High development of one part of an organ, at the expense 

 of other adjoining parts. — This principle may be said to include 

 the preceding, since, in that, there is a high development of the 

 anterior or cephalic portion of the structure at the expense of the 

 posterior or circumferential. But here, there is reference to 

 special organs rather than to the structure as a whole. Thus, in 

 the foot of a Horse, there is an enlargement of one toe^ normally 

 the third, at the expense of the others, and this enlarged toe has 

 the full normal strength that belongs to the foot under the Her- 

 bivore-type. 



It is apparent from the facts in paragraphs (1) and (2), that 

 there may be an elliptic method of cephali zation as well as of de- 

 cephalization. The Crab-type is a striking example of the former. 

 The foot of the Horse, considering separately the Horse-type^ is a 

 case under the former rather than the latter ; for, in any related 

 species, a lessening of the disparity of the toes would be evi- 

 dence of weakness and inferiority under that type. Yet, as com- 

 pared with the higher Cai'nivore-type, in which the life-system has 

 the strength to develop all the toes in their completeness and ful- 

 ness of vigour, with great strength of foot, the foot of the horse is 

 elliptic, and a mark of inferior cephalization. In the typical 

 Kuminants, the complete series of teeth is indicated in an embry- 

 onic state before birth ; but part of them fail of development, while 

 the others — those specially characteristic of the type — go forward 

 to great size and perfection. As in the foot of the Horse there is 

 here an enlargement of one portion at the expense of the others. 

 And this, under the Ruminant-type, is progress toward the highest 

 condition of the type, or cephalization by an elliptic method. A 

 Ruminant in which the teeth should be all equally developed 

 would be one of too great feebleness of system to carry the struc- 

 ture to its typical perfection; and such is the Eocene Anoplothere.* 

 If, however, the Ruminants were referred to the Megasthene-type 



^ " Amongst the varied forms of existing Herbivora we find certain teeth 

 disproportionately developed, sometimes to a monstrous size ; whilst other 

 teeth are reduced to rudiraental minuteness, or are wanting altogether : but 

 the number of teeth never exceeds, in any hoofed quadruped, that displayed 

 in the dental formula of the Anoplotherium. It is likewise most interesting 

 to find that those species with a comparatively defective dentition, as the 

 horned Kuminants for example, manifest transitorily, in the embryo-state, the 

 germs of upper incisors and canines, which disappear before birth, but which 

 were retained and functionally developed in the cloven-footed Anoplothere." — 

 Goodsir, British Assoc. Rep. 1838. Owen's Brit. 3Iamm., 1846, p. 433. 



