216 AVES : PYGOPODES. — XXXI. 
bluish, with dark band; young and winter plumage different, the 
bill unmarked, but the bird resembles nothing else. L. 14. W. 5 
B.1. Whole of America, abundant. (Lat., podex, rump ; pes, foot.) 
Famiry CXXV. URINATORIDAS. (THE Loons.) 
Bill long, strong, tapering, acute, wholly hard; nostrils linear. 
Head densely and evenly feathered, without ruffs or naked spaces ; 
eye large. Feet 4-toed, palmate; tarsus reticulate, strongly com- 
pressed. Wings comparatively long and strong; tail short but 
well developed. Precocial. Genus 1; species 5. Birds of large 
size, with strong powers of flight, and pre-eminent in swimming and 
diving, but scarcely able to walk; they are migratory, breeding north- 
ward, ; but coming 8. in winter ; the voice is singularly sharp and wild. 
321. URINATOR Cuvier. 
a. Tarsus shorter than middle toe, without claw. 
631. U. imber (Gunner). Common Loon. Diver. Black; 
breast and below chiefly white; head and neck iridescent, black in 
summer; a patch of white streaks on each side of neck and on the 
throat; back with many white spots; 9 duller, brownish above, 
without the head markings. L. 28 to 36. W.14. Ts. 3. B. 3. 
Northern Hemisphere; whole U.S. in winter. (Zu.) (Norwegian 
name. ) 
632. U. arcticus (L.). Biack-THROATED Loon. Similar, but 
head and neck behind bluish or hoary gray; foreneck purplish 
black, with a crescent of white streaks; 9? duller. L. 28. W. 12. 
B. 24. Northern hemisphere, not common in U.S. (£u.) 
aa. Tarsus longer than middle toe with claw. 
633. U. lumme (Gunner.) ReEp-THROATED Loon. Blackish, 
streaked on neck, chiefly white below; head and neck mostly bluish 
gray; throat with a large chestnut patch in summer; @ duller. 
L. 27. W.11. B.2. Northern regions, U.S. in winter. (Eu.) 
(Norwegian name.) 
Famity CXXVI. ALCIDA. (Tue Avxs.) 
Feet palmate, three-toed; tarsus reticulate or partly scutellate; 
suffrago naked; claws ordinary; bill and nostrils various; tail per- 
fect, of few feathers; lores feathered; legs variable, set far back; 
color variable, the head often with curly crests; altricial; eggs few. 
Genera 12; species about 35, living about rocks on rugged shores 
in Northern regions. Most of them fly well and all swim on or 
under water with equal ease. They feed chiefly on fishes. 
a. Inner claw much larger and more curved than the others; corner of mouth 
with a ‘‘ rosette ’’ of thick naked skin; bill greatly compressed, almost as 
decp as long. (Fv aterculine.) 
