374 NATATORES. MERGUS. 



tarsus. Hind toe reaching to the ground, and furnished 

 with a large lobated membrane. ' 



General form rather long, much depressed or flattened. 

 Head more or less crested. 



The members of this genus are distinguished from the 

 preceding subfamilies of the Anatidce, by the narrowness of 

 the bill, as compared with its length, and by the structure 

 of its laminated edges, which assume the form of distinct co- 

 nical teeth, generally pointing backwards, instead of the 

 broad transverse plates or laminae of the other groups. The 

 food of the typical species principally consists of fish, for se- 

 curing which this modification of bill is admirably adapted. 

 The members of this genus swim well, but, from the weight 

 and flattened form of their bodies, appear deeply immersed 

 in the water ; the head, neck, and back being only visible. 

 They are also excellent divers, moving or rather flying be- 

 neath the surface with great rapidity, and to a great dis- 

 tance at a time, and by these submarine flights they capture 

 their finny prey. Their flight is strong and swift, and they 

 have great endurance on wing ; but, from the shortness and 

 backward position of the legs, are awkward upon land. They 

 are natives of the colder climates, and are found, during the 

 summer (or breeding season), in very high latitudes. The 

 males, after the sexual connexion, are subject to a partial 

 change in the colours of their plumage, similar to that which 

 takes place in many species of the subfamily Anatina. The 

 labyrinthic part of the trachea (only in the male bird) is 

 very large and complicated, and the tube itself varies in 

 form and in the number of its enlargements, according to the 

 species. The young males bear a strong resemblance to the 

 females, till after the second moult. 



