EVIDENCES OF EVOLUTION. 131 



Generalized Types. 



Confirmatory of the argument founded on the re- 

 markable series of transitional forms we have just been 

 considering, are those curious extinct animals called 

 by Huxley generalized, and by Dana, comprehen- 

 sive types ; types which by Agassiz were variously 

 designated as combining, connecting, synthetic and 

 prophetic types, and which embrace those strange 

 creatures that embodied the characters of two or 

 more groups at present widely separated from each 

 other. Among these were certain early verte- 

 brates which possessed both fish-like and reptilian 

 characters. At a later geologic epoch there existed 

 other animals, which possessed the characters of rep- 

 tiles and birds in such a curious combination, that we 

 are yet unable to decide whether they should be 

 called reptilian birds or bird-like reptiles. Among 

 these generalized types there were, in the words of 

 Grant Allen : " Lizards that were almost crows, mar- 

 supials that were almost ostriches, insectivores that 

 were almost bats, rodents that were almost mon- 

 keys." "Just on the stroke, when they were most 

 needed," declares the same writer, "connecting links 

 turned up in abundance between fish and amphibians, 

 amphibians and reptiles, reptiles and birds, birds and 

 mammals, and all of these together in a perfect net- 

 work of curious cross-relationships." 



Among these generalized forms may be men- 

 tioned the archceopteryx, the pterodactyl and the 

 compsognathus. "In the archceopteryx" says Hux- 

 ley, " we have an animal which, to a certain extent, 

 occupies a midway place between a bird and a 



