of the United States. 415 



our seven genera. Related by some links to the Longipen- 

 nes, by Mergus to the Lamellosodentati, and by Alca impen- 

 nis to the Impennes, which return into the Steganopodes. 



A. Feet 4-toed. 



Urinatores, Vieill. Colymbi, Boie. Marangoni, Ranz. 

 Colymbida, Vigors. 



* Toes lobated. 

 83. PODICEPS. 



Colymbus, L. Gm. Briss. III. Ranz. Podiceps, Temm. 

 Vieill. 



Bill moderate, rather slender, robust, hard, straight, com- 

 pressed, conic-elongated, acute, entire ; upper mandible 

 deeply and broadly furrowed each side at base, somewhat 

 curved at tip ; lower navicular ; edges bent in : nostrils in 

 the furrows, basal, lateral, concave, oblong, pervious, poste- 

 riorly half closed by a membrane : tongue moderate, acute, 

 slightly emarginate at tip. Head small, oblong ; lores naked; 

 eyes near the bill ; neck rather long, slender : body boat- 

 shaped, back elevated. Feet turned outward, placed ex- 

 tremely far back ; tibia almost hidden in the belly ; tarsus 

 shorter than the outer toe, exceedingly compressed, carinated 

 before and behind, posterior carina doubly serrated ; anterior 

 toes greatly depressed, connected at base by a membrane 

 forming a broad lobe all around each toe, outer toe longest, 

 lobe of the middle toe broad, subequal, thrice as broad as 

 that of the lateral ; hind toe compressed, articulated inter- 

 nally with the tarsus, equal to a phalanx of the fore toe, 

 edged with a very narrow membrane, internally with a broad 

 rounded one : nails much depressed, quite plane, broad ob- 

 tuse, not reaching beyond the lobes ^ middle one largest, 

 slightly pectinated ; hind nails very small. Wings short, 

 narrow ; three outer primaries subequal, longest. Tail 

 wanting, in its place a small tuft of short downy feathers. 



