grou:n"ds an'd consequen"ces of evolution. 343 



plexity and embarrassing synon3miy. Mr. Meek described 

 a common Cincinnati fossil as OrfJiis hlforata with four 

 varieties.* Professor Nicholson has taken our old Chcetefes 

 hjcoperdon, a common coral of the Lower Silurian rocks, 

 and enumerated no less than twenty-five distinct variations. f 

 Spirifera disjuncta is a brachiopod abundant in Chau- 

 tauqua count}^, New York, and neighboring regions, and 

 of this Professor Hall has fissured no less than eisrhteen 

 ' varieties. J Of Atnjpa reticularis he gives us, similarly, 

 sixteen varieties. These technical names are edifying to 

 the general reader only so far as they demonstrate that 

 great variability has existed in the history of extinct 

 forms, whether we attribute this to hybridity, geograph- 

 ical position or other causes, and furnish additions to the 

 stock of evidence that it is the economy of nature to 

 effect transmutations of species. The sum total of the 

 variational evidence shows us that the derivative origin 

 of types in palseontological history is a natural possi- 

 bilit}'. We are not in conflict w^ith nature, therefore, in 

 inferring that the terms of the palaeontological series sus- 

 tain a consanguineous relation. 



But in the fourth place we have the emhryological 

 evidence. This seems to us to bring all the other evidence 

 to a focus and complete the conviction that the deriva- 

 tive origin of species is a fact. It affords not only a 

 picture of the succession of extinct forms, but it is a 

 picture in which the successive terms are knoirn to be 



*Meek, Palosontology of Ohio, pi. x. Compare Hall, Palceontology of New 

 York, i, 133, pi. xxxii D. 



tH. A. Nicholson, PalxontoJogy of Ohio, ii. 



i J. Hall, Palaeontology of New York, \\\ pi. xli, xliii. 



J. Hall, Palaeontology of New York, pi. li-liii. Compare Wliitlield, XIX 

 Rep. N. Y. Regents. 



