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FAMILY II. COLYMBID^E. 



FROM the natatorial groups of the Anatida, distinguished, 

 as we have seen, from the rest of that family by the flattened 

 form of the body, the backward position of the legs, the 

 shortened and concave wings, and by habits more decidedly 

 accordant with a life on the ocean, we now pass on to the 

 family of the Colymbida,. Here we shall find the above cha- 

 racteristics displayed in a still greater degree, and which, as 

 contributing so essentially to the perfection of this mode of 

 existence, render this family one of the typical divisions of 

 the Order. In the birds which compose it, the legs are 

 placed at the extremity of the body, with which they form 

 an acute angle, acting, as it were, as propelling oars from 

 the stern. The tarsi and feet alone are exposed and free ; 

 the tibia and femur being inclosed within the integuments 

 of the abdomen. The tarsus is remarkably thin, or laterally 

 compressed ; and the feet (although large, and furnished with 

 membranes) have the toes so articulated, as to fold into a 

 very small compass when drawn towards the body after ma- 

 king the necessary stroke, thus offering the least possible re- 

 sistance in the water. The lobated hind toe possessed by the 

 more aquatic ducks is still retained in this family, and, in 

 some members of it, is joined to the inner toe by a small 

 uniting membrane, shewing thus a connexion also with the 

 Pelecamda. The contour of the body is oval, broad, and 

 depressed, narrowing towards the neck, which is long and 

 tapering. The wings are short and concave, as well, or per- 

 haps even better, adapted for aiding progression beneath the 

 surface of the water, as through the air. The bill is strait 

 and compressed, ending in a sharp point, and destitute of 

 the cuticular membrane that envelopes it in the Anatida. 

 From the backward position of the legs the individuals of 



