The Mergansers 31 



lamellae of varying development ; the number of tail- 

 feathers varies from fourteen to twenty-four ; the legs 

 are short and the anterior toes fully webbed ; the hind 

 toe is small and jointed above the level of the others ; 

 the eggs are numerous, white, pale greenish or creamy, 

 and unspotted ; the young are covered with down when 

 hatched, and able to run or swim at once. 



AU the North American genera are included in a single 

 family — Anatidce. This, for convenience, can be divided 

 into five subfamilies, as follows : — 



liEY OF THE Subfamilies. 



A. Tarsus as long as the middle toe without claw ; with reticulate 



scales all round. 



a. Neck very long, as long as the body ; lores naked in the adults. 



Cygninje, p. 71. 



b. Neck moderate, no naked patch on the lores. 



Anserinse, p. 65. 



B. Tarsus shorter than the middle toe without claw, scuteUate 



in front. 



a. Hind toe not lobed. Anatinae, p. 35. 



b. Hind toe lobed. 



a^ Bill flattened and depressed. Fuligulinse, p. 49. 



b^ BiU cylindrical and compressed. Merginae, p. 31. 



Subfamily MERGIN-^. 

 The Mergansers have a narrow, almost cylindrical, 

 bill, with the lamellae only present in the upper man- 

 dible and developed into prominent tooth-like serrations ; 

 tarsi compressed, scutellate anteriorly ; hind toe lobate ; 

 head usually crested ; sexes unlike. 



IvEY OF THE GeNERA AND SpECIES. 



A. Bill chiefly red, about as long as the head ; crest low and only 



in the occipital region (Mergus). 



a. Nostrils near the middle of the bill, breast all white in S 



M. americanus, p. 32. 



b. Nostrils nearer the base of the bill ; breast with a patch of 



reddish-brown in <? M. serrator, p. 33. 



B. Bill chiefly black, shorter than the head ; crest highly developed, 



erect and semicircular (Lophodytes). L. cucullatus, p. 34. 



