SWIMMING BIRDS. 



465 



FIG. 393. COMMOX TET?X. 



The Skimmers (Eliyncliops] resemble the Sea Swallows in the 

 smallness of their feet, their long wings, and their forked tail, but 

 are distinguished from all other birds by the extraordinary structure 

 of their beak the upper mandible is much shorter than the lower, 

 and both so flattened sideways that they resemble horny blades, the 

 edges of which meet without fitting into each other. These birds, 

 therefore, only obtain their food by skimming the surface of the 

 water as they fly, by means of their projecting lower jaw. 



The next family, Totipalmatse,* is recognizable from 

 the circumstance that all the four toes, including the 

 hind one, are webbed together by membrane, thus 

 constituting them the most perfectly constructed for 

 swimming of the whole race, and yet notwithstanding 

 this, they are the only Palmipedes that perch on 

 trees ; their legs are short, and they are all excellent 

 swimmers. To this family belong 



The Pelicans (Pelecanida&\ comprehending those genera which 

 have a space at the base of their beak denuded of feathers. Their 

 nostrils are slits, the openings of which are scarcely perceptible ; the 



* Totus, entire ; palma, the sole of the foot ; so called because 

 their toes are united together by one continuous web. 



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