PHYLOGENY. 



125 



developed among rasorial types in the sand-grouse, 

 and, among the adjacent forms, the pigeons. Then 





I 



■^h 



rig. 32. — ArchtEopteryx lithographica, 

 1 in the middle Oolite of Bavaria. 



among the lower Passeres, the humming-birds exceed 

 all birds in their powers of flight, and the swifts and 



