BIRDS 



OF 



EASTERN NORTH AMERICA. 



SUB-CLASS I. NATATORES. WEB-FOOTED BIRDS. 



Feet, palmate, that is, the anterior, and >sc>:\ietime.s the posterior, toes are con- 

 nected BY more or less PROMINANT WEBS. 



Birds characterized by the above jieculiarity, spend a greatei- poi-tioii ot'tlicir time 

 on tlie water or near it, and their food consists, in a great measure, of aquatic animals 

 and plants. 



The gnmp is. however, not natural, for there is no aljsolutc division lietween it and 

 the next sub-class. In it are some highly specialized families that possess osteological 

 characters which indicate that if their remote ancestral origin was ever the same tiie 

 connecting forms ha\e long been lost. For example, althoiigh the Man-of-war and tiie 

 Albatross are remarkably strong Hying birds, having many habits in common, wl they 

 are as widely cliflerent in structure as almost any two species of birds can vei'\ well be, 

 while neither have scarcely anytliing in common with the short-winged, weakl\- tl\ino- 

 Grebes. 



Ml'- 



,\)VJ 



Fig. 1. Head of Murre, Uria troile. 



