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.) 



FAMILY CXXV. URINATORID^J. (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 S. 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. (Eu.) (Norwegian 

 name.) 



632. U. arcticus (L.). BLACK-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. 2^. Northern hemisphere, not common in U. S. (Eu.} 



aa. Tarsus longer than middle toe with claw. 



633. U. lumme (Gunner.) RED-THROATED LOON. Blackish, 

 streaked on neck, chiefly white below ; head and neck mostly bluish 

 gray; throat with a large chestnut patch in summer; 9 duller. 

 L. 27. W. 11. B. 2. Northern regions, U. S. in winter. (Eu.) 

 (Norwegian name.) 



FAMILY CXXVI. ALCID^B. (THE AUKS.) 

 Feet palmate, three-toed; tarsus reticulate or partly scutellate; 

 suffrage 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 

 deep as long. (Fraterculince.) 



