I 



L ikeiiesses ; or, Philosophical A natomy 2 6 1 



though it exists in no other known beast. The resemblance 

 which exists between Pelohates, the turtle, and Lophiomys 

 must be supposed to have been occasioned independently, 

 and not by inheritance. Again, the African ant-eater, the 

 aard-vark (Orycteropus), has each tooth, though apparently 

 simple, really composed of a closely set bundle of very fine, 

 long, cylindrical teeth united together side by side. Such a 

 structure exists in no other genus of the same class, but is 

 found in the class of fishes — namely, in the skate (Mylio- 

 hatis). Yet the aard-vark can have no special relation of 

 genetic affinity with these fishes. The shape of the teeth in 

 kangaroos is similar to that of certain shrew-like, insect- 

 eating African beasts (of the genus Macroscelides), which also 

 agree with kangaroos in having the hind-legs and feet much 

 elongated and a jumping mode of progression; yet this 

 double similarity is almost evidently induced and not 

 inherited. The only beasts of burthen known in South. 

 America when it was discovered by the Spaniards, were the 

 llamas, animals which present a singular structure as to 

 the course of their vertebral arteries, which pierce the 

 neck-bones on their inner sides. The very same condition, 

 however, occurs again in the great ant-eater, also an inhabi- 

 tant of South America. Yet it is impossible to beheve that 

 any special affinity, through descent, can connect such 

 strangely divergent forms. It is also noteworthy that this 

 character can hardly have been due to any action of * natural 

 or sexual selection.' The examples cited are but a few of 

 many which might be adduced as evidence in this matter. 



It has then been forced upon our attention (alike by the 

 facts of lateral and serial homology, as well as by such as 

 those just cited) that there are likenesses or homologies \ ^^ 

 which cannot be due to inheritance, and which have to 

 be distinguished from others which are, or which may be, so 

 due. With the new mental conception came, as was fitting. 



