THE BEGINNINGS OF FLIGHT 



11 



tissue. Little by little the line of feath- 

 ers and their coverts sank into insigni- 

 ficance and became lost among the body 

 plumage. It affords an excellent ex- 

 ample of what Professor Henry F. 

 Osborn would call the phylogenetic 

 acceleration of a character, followed by 

 its gradual reduction. 



Millions of years after they were of 

 use, the feathers of the pelvic wing are 

 still reproduced in embryo and nestling. 

 And for some unknown reason, Nature 

 makes each squab pass through this 

 Tetrapteryx stage. The line of feathers 



along the leg of the young bird repro- 

 duces in this diminutive, useless way the 

 glory that once was theirs. No fossil 

 bird of the ages prior to Archoeopteryx 

 may come to light, but the memory of 

 Tetrapteryx lingers in every dove-cote." 

 Thus were scaly, creeping reptiles, 

 transformed into feathered, flying birds, 

 the more marked stages in the process 

 being indicated in the accompanying 

 diagrammatic figures which, with the 

 cut of Tetrapteryx have been kindly 

 loaned to the Journal by the New York 

 Zoological Society. 



Restoration of Archaeoptery x 

 After W. P. PycrafI 



