Paleontology. 1 99 



wise furnish characters which further serve to establish 

 this dual relationship 1 ." 



The evidence, then, which is furnished by all parts 

 of the vertebral skeleton whether we have regard to 

 Fishes, Reptiles, Birds, or Mammals is cumulative 

 and consistent. Nowhere do we meet with any de- 

 viation or ambiguity, while everywhere we encounter 

 similar proofs of continuous transformation proofs 

 which vary only with the varying amount of material 

 which happens to be at our disposal, being most 

 numerous and detailed in those cases where the 

 greatest number of fossil forms has been preserved 

 by the geological record. Here, therefore, we may 

 leave the vertebral skeleton ; and, having presented 

 a sample of the evidence as yielded by horns and 

 bones, I will conclude by glancing with similar brevity 

 at the case of shells which, as before remarked, con- 

 stitute the only other sufficiently hard or permanent 

 material to yield unbroken evidence touching the 

 fossil ancestry of animals. 



Of course it will be understood that I am everywhere 

 giving merely samples of the now superabundant 

 evidence which is yielded by palaeontology ; and, as 

 this chapter is already a long one, I must content 

 myself with citing only the case of mollusk-shells, 

 although shells of other classes might be made to 

 yield highly important additions to the testimony. 

 Moreover, even as regards the one division of mollusk- 

 shells, I can afford to quote only a very few cases. 

 These, however, are in my opinion the strongest 

 single pieces of evidence in favour of transmutation 

 which have thus far been brought to light. 



1 Heilprin, Geological Evidences of Evolution, pp. 73-4 (1888). 



