OKDEK VI. 



NATATORES. 



Ch. — Toes connected by membrane to the claws ; the feet fitted for swimming. Lower part of tibia usually feathered to near 

 the joint, which is bare. Hind toe, however, usually elevated, and ratlier small, except in Pelecanidae. Fitted for an aquatic 

 life, swimming and diving freely. Rump wilh well developed oil glands. 



Tlie order Natatores, as characterized above, embraces a large number of species of very 

 varied forms, all more or less aquatic in their habits. A character common to all consists in 

 the presence of a membrane between the toes, usually extending to the claws. This membrane, 

 when found in the Grallatores, is confined more or less to the basal joint, unless Phoenicopterus 

 be an exception. This genus has been variou.sly placed in both orders, and it is still a question 

 ■where it really belongs. The internal anatomy resembles that of the Natatores, as well as the 

 lamellated bill and fully webbed toes ; the external form, however, as well as habits, bring it 

 nearer the Grallatores. 



With the exception of Phoenicopterus, if it really belong here, the legs of the Natatores are 

 generally rather short, and with the tibia more covered with feathers inferiorly than in Gralla- 

 tores. They are inserted rather far back, so that, when standing erect, the body of the bird is 

 generally nearly upright. The tibia are buried to a considerable extent in the muscles of the 

 trunk, which are much developed. 



The order Natatores of most authors has been divided by Bonaparte into two — the Gaviae and 

 the AnseVes ; the former embracing species which rear their young in nests, and belong to the 

 B\ib-c\a,ss Altrices ; while the latter are Praecoces, the young procuring food for themselves 

 almost from birth. There are no single external characters by which to distinguish these two 

 orders or sub-orders, as I shall make them in the present report. 



Gaviae. — Bill without lamellae, and more or less entire. Feet with the toes all connected 

 by one continuous membrane ; or the hind toe free, with the anterior continuously webbed. 



ANSEREi. — Bill with transverse lamellae along the edges. Hind toe free. 



The Anseres of Bonaparte, as first established by him, included the Urinatores, (of the opposite 

 page,) but he subsequently transferred them to the Gaviae. 



