ANSER. 61 



in several of the species continued, and we see 

 in them the greatest perfection in the structure of 

 the bill In the Fuligulinae, or scaups and po- 

 chards, &c. we see the time spent almost entirely 

 on the waters, the powers of swimming and div- 

 ing augmented, while the wings in many are pro- 

 portionally short; and in the last sub-family, or 

 the Mergansers, the habits are more aquatic still, 

 their progress when upon land, which is only during 

 the time of breeding, more constrained, and their 

 food composed almost entirely of fishes, for the 

 holding fast of which their bill is strongly toothed 

 or serrated. In the males of most of the species 

 there is a dilatation or bony labyrinth in the wind- 

 pipe or trachea, the use of which seems scarcely to 

 be understood, while in others, as the swans, it 

 performs a doubling or a convolution in the interior 

 of the sternum. In all the species we have- exa- 

 mined, this structure is different in each, and pre- 

 sents a distinguishing mark where they are closely 

 allied. The geese of the Rasorial form is charac- 

 terised in 



ANSER, Brisson. Generic characters. Bill 

 somewhat conical in shape, narrower than the 

 head, elevated at the base ; lateral laminae in 

 the form of blunt teeth, slightly developed, 

 and apparent exteriorly ; nostrils central, rather 

 large, pierced entirely through ; wings pointed, 

 ample, tuberculated ; legs placed under the 

 centre of the body, tarsi rather long, hallux 



