842. 
843. 
844. 
COLYMBIDZ: LOONS. 791 
©. are'ticus, (Lat. areficus, arctic.) BLACK-THROATED Diver. Bill generally as in tor- 
quatus, but smaller; color black. Chin, throat, and neck in front, black, with purplish and 
violet reflections on the sides of the head, gradually fading into a fine, clear bluish-gray, deep- 
est on forehead, lightest behind, and separated from the black of the throat by a series of white 
streaks. A crescent of short, white streaks across upper throat; sides of breast striped with 
pure white and glossy black, these stripes nearly meeting in front. Entire upper parts deep, 
glossy greenish-black, each feather of scapulars and intersecapulars with a white spot near end 
of each web; those of the scapulars largest, forming four patches in tranverse rows. Wing- 
goverts thickly speckled with small ovate white spots. Inner webs of quills, and tail-feathers 
below, light grayish-brown. Sides under wings like back. Lining of wings and entire under 
parts from the neck, pure white, with a narrow dusky band across lower belly; under tail- 
‘coverts dusky, tipped with white. Young: Bill light bluish-gray, dusky along the ridge. 
Iris brown. Feet dusky. Upper part of head and neck dark grayish-brown; sides of head 
dull grayish-white, minutely streaked with brown. Upper parts with a reticulated or scaly 
appearance, the feathers being brownish-black with broad bluish-gray margins; the rump 
dull brownish-gray. Primaries and their coverts brownish-black ; secondaries and tail-feathers 
dusky margined with gray. Fore-part of neck grayish-white, minutely and faintly dotted with 
brown; its sides below streaked with the same. Lower parts, including under surface of 
wings, pure white, the sides of the body and rump, with part of the lower tail-coverts, dusky, 
edged with bluish-gray. (Audubon.) Dimensions: length about 30.00; extent 40.00; 
wing 12.00; bill along culmen 2.45; along gape 3.40; its height at nostrils 0.65; its width 
there 0.35; tarsus 2.90; outer toe and claw 3.80. N. Hemisphere; not common in the U. 8. 
C. a, paci/ficus. (Lat. pacificus, pacific.) Paciric BLAcK-THROATED Diver. Like the 
last; colors the same. Size less ; length 24.00; wing 11.00. Bill shorter. slenderer, somewhat 
differently shaped, with straight culmen — much like the difference between Auchmophorus 
occidentalis and 4%. clarki. Bill along culmen 1.90-2.20; gape 3.00; length of bill 0.50 or 
less; tarsus about 2.50. N. W. America; abundant on Pacific coast of U. 8. in winter. 
C. septentriona/lis. (Lat. septentrionalis, northern.) Rep-THROATED Diver. Bill usually 
slenderer than in the foregoing; culmen slightly concave at the nostrils, gently convex to tip, 
which is rather obtuse and a little decurved. Outline of rami nearly straight; gonys slightly 
convex. Froutal antie scarcely extending beyond base of nostrils. Tarsus relatively rather 
longer than in foregoing species, about four-fifths the middle toe. Adult: Bill black, rather 
lighter at the tip. Crown and broad cervical stripe glossy greenish-black, the latter thickly 
streaked with white, which streaks, on the sides of the breast, spread so as to nearly meet in 
front. Throat and sides of head clear bluish-gray. A large, well-defined, triangular, chest- 
nut-brown throat-patch. Entire upper parts and sides under the wings deep brownish-black, 
with greenish gloss, everywhere profusely spotted with white, the spots small, oval. Prim- 
aries blackish, paler on the inner webs. Tail narrowly tipped with white. Under parts and 
lining of wings white, the axillars.with narrow dusky shaft-streaks, and the lower belly, with 
some of the under tail-coverts, dusky. Young: Bill mostly light bluish-white, with dusky 
ridge. Crown of head and neck behind bluish-gray, the feathers of the former bordered with 
whitish. Entire upper parts brownish- or grayish-black, everywhere profusely marked with | 
small oval and linear spots of white. Throat without red patch, its sides and those of the 
head mottled with dusky. Other parts as in the adult. Length 25.00; extent 44.00; wing 
11.00 or less; bill along culmen 2.00; along gape 3.00; height at nostril 0.50; width there 
0.35 ; tarsus 2.75 ; outer toe 3.50. Varies greatly in size, and in the size and shape of the bill; 
recognized by the profuse spotting of the upper parts, as well as, when adult, by the red throat- 
patch. The spots are smallest and most numerous on the wing-coverts and upper back, where 
they grade into the streaks of the hind neck; largest on the tertials, scapulars, and sides under 
the wings, where they are rather lines than spots, and are fewest, or almost wanting, ou the 
