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. 
Colymbidce , Vigors. 
* Toes lobated. 
83. PODICEPS. 
Colymbus, L . Gm . Briss . 1ZZ. 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 ; low£r 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. 
