338 ALCIDEH, AUKS.—GEN. 315. 
tarsus 14; middle toe and claw 13. Central America, West Indies and 
Mexico, Texas, Southern Colorado, Lower California. Sylbeocyclus domi- 
Micus COUESs (ls Cl Olt ee ke Ghee) Mee ener Uo eiaetie ce eee me OMIM ONan 
815. Genus PODILYMBUS Lesson. 
Pied-billed Grebe. Dab-chick. Dipper. Diedapper. Water-witch. 
Length 12-14; wing about 5; bill 1 or less; tarsus 13. Adult: bill 
bluish, dusky on the ridge, encircled with a black bar; throat with a long 
black patch ; upper parts blackish-brown ; primaries ashy-brown, secondaries 
ashy and white; lower parts silky-white, more or less mottled or obscured 
with dusky; the lower neck in front, fore breast and sides, washed with 
rusty. Young: lacking the throat patch and peculiar marks of the bill, 
otherwise not particularly different ; in a very early plumage with the head 
curiously striped. N. Am., very abundant. Nurv., ii, 259; AUD., Vil, 
324,-pl..483> Lawre. in tBD., 898: 5 2 )oes) 2) een 0 eee PE ODICK ER: 
Family ALCIDA. Auks. 
Feet three-toed, palmate. Bill horny, non-lamellate, of extremely variable shape, 
often curiously appendaged; nostrils variable, but not tubular. Wings and tail 
short; tarsi shorter than the middle toe and claw. Form heavy, thickset. 
Birds of this family will be immediately recognized by the foregoing circum- 
stances, taken in connection with general pygopodous characters. Agreeing closely 
= in essential respects, they differ among 
themselves to a remarkable degree in the 
form of the bill, with every genus and 
==] almost every species; this organ frequently 
| assuming an odd shape, developing horny 
| processes, showing various ridges and 
furrows, or being brilliantly colored. It 
is the rule that any soft part that may be 
observed on the bill will finally become 
hard, or form an outgrowth, or both; and: 
such processes, in some cases at least, are 
temporary, appearing only during the 
breeding season. ‘The bill, besides, varies 
ereatly with ‘age, in size and shape, often 
showing at first little trace of its adult 
character. In gen. 316-7 the bill is high, 
compressed, with curved vertical colored 
erooves, the nostrils densely feathered ; in 
318-23, the feathers are remote from the 
nostrils, and the bill reaches its maximum 
of diversity and singularity of contour ; 
in the rest, the bill is of simpler shape, 
Fie. 215. Great Auk. usually conico-elongate, with more or less 
perfectly feathered nostrils. The general coloration is simple; but many species 
develop very remarkable frontal or lateral crests; the sexes are alike; the 
young different; seasonal changes are almost always strongly marked. 
