88 THE GENESIS OF SPECIES. [Chap. 



in the vertebrates on tlie one hand, and in the moUusks on 

 the other, present us with residuary phenomena for which 

 " Natural Selection" alone is (|uite incompetent to account : 

 and that these same phenomena must therefore be con- 

 sidered as conclusive evidence for the action of some other 

 natural law or laws conditioning the simultaneous and 

 independent evolution of these harmonious and concordant 

 adaptations. 



Provided with this evidence, it may be now profitalJe to 

 enumerate other correspondences, which are not perliaps in 

 tliemselves inexplicable by '' Xatural Selection," but which 

 are more readily to be explained by the action of tlie 

 unknown law or laws referred to — which action, as its 

 necessity has been demonstrated in one case, becomes 

 a priori probable in tlie others. 



Thus the i^^reat oceanic Mammalia — the whales — show 

 striking resemblances to those prodigious, extinct, marine 



---^.■■'■^■v■,A''?'^•^\•^ ,T ,,^. 



SKELETON OP AN' ICHTHYOSACRCS. 



reptiles, the Ichthyosauria, and this not only in structures 

 readily referable to similarity of habit, luit in such matters 

 as greatly elongated premaxillary bones, together with the 

 concealment of certain bones of the s-kull by other cranial 

 bones. 



Again, the aerial manmials, the bats, resemble those flying 

 reptiles of the secondary epoch, the pterodactyles ; not only 

 to a certain extent in the breast-bone and mode of support- 



