Wilder.] 314 [June 21, 



mologies, the relative normal position has been found to be of greater 

 morphical value than size, than function, than natural attitude, and 

 finally than even numerical composition; and yet, when we ask anat- 

 omists to consider the other evidences of meketropy, which are pre- 

 sented by the development and structure of the body, and show that 

 even the adult membra offer no difficulties in their proximal 

 portions, and that in the embryo, no difference of size or segmen- 

 tation exists in the manus and pes, they hold to the syntropical com- 

 parison, partly because of its antiquity and general acceptation; 

 partly because of the similarity of pollex and primus in that mor- 

 phological anomaly, the human body ; partly because in the natu- 

 ral attitude of the manus with quadrupeds, the pollex becomes the 

 inner digit like the primus; but chiefly because with many Mam- 

 malia pollex and primus differ in numerical composition from the 

 other digits and dactyls : and this in spite of the fact that for the 

 determination of every other case of homology, all these considera- 

 tions have been set aside in favor of the single character, relative 

 normal position. 



In reference to this question, some other facts and arguments 

 should be considered. 



1. That with most members of the group called Perissodactyla, 

 (Ow., 62, 2, 283; Fl., 71, 3,) including the existing genera Ehinodceros, 

 Hyrax, Tapirus, and Equus, and many extinct genera, the pollex and 

 minimus, the primus and quintus are wanting, 1 so that, were the prob- 

 lem to be decided for them alone, no objection would arise respecting 

 these outer digits and dactyls; and the argument that such a question 

 cannot be decided upon evidence drawn from a single group, applies 

 with equal force to the consideration of the Mammalia alone out of 

 all the vertebrate branch; and, as has been already stated, the objec- 

 tion derived from the numerical composition of certain digits and 

 dactyls, would never have arisen among the members of the lower 

 classes of vertebrates. 



2. That it is not yet determined whether the so-called pollical 

 metacarpal (^ pollicis) and primal metatarsal (J primi) should not be 

 regarded rather as proximal phalanges of the pollex and primus, as 

 Qken (284, Par. 2382) and Maclise (23, 663) are inclined to believe; 

 this view is not obviously inconsistent with the observations of Thom- 

 son and Humphrey (305) upon the mode of ossification of these parts, 

 and Flower admits (71, 255) that the question is not decided. 



1 Tapirus retains the minimus and Hyrax the minimus and a rudimentary pollex. 



