32 EVOLUTION 



from some ancient reptilian or saurian stock. 

 He has not ceased to wonder how this tran- 

 sition can have come about; "how the slow, 

 cold-blooded, scaly beast ever became trans- 

 formed into the quick, hot-blooded, feathered 

 bird, the joy of creation"; but he does not 

 doubt that the transition was effected. He 

 is still unwilling to make any positive state- 

 ment in regard to the precise pedigree of 

 birds, and yet he is confident that they 

 sprang from a reptilian stock. What are 

 the reasons for this confidence? 



They are threefold: — (1) There are, in spite 

 of appearances, numerous structural resem- 

 blances between birds and reptiles, from the 

 scales on the feet to the composition and the 

 articulation of the lower jaw; (2) there are 

 deep similarities in development, for the 

 embryo bird and the embryo reptile travel 

 at first along parallel paths, and only grad- 

 ually part company; and (3) there are 

 extinct types which to some extent bridge 

 the conspicuous gap. A word, then, in regard 

 to these connecting links. 



One of the most treasured fossils in the 

 world — of which the British Museum and 

 the Berlin Museum have each one of the 

 two known specimens — is the oldest known 

 bird, Archseopteryx. These priceless skele- 

 tons were found well preserved in the lith- 



