te 
4. 
COLYMBIDZ: LOONS. 791 
C. are’ticus. (Lat. arcticus, 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 interscapulars with a white spot near end 
of each web; those of the scapulars largest, forming four patches in tranverse rows. Wing- 
coverts 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'fieus. (Lat. pacificus, pacific.) Pactric 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 A’chmophorus 
occidentalis and 42. 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. Frontal antiz 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 mottied 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, seapulars, and sides under 
the wings, where they are rather lines than spots, and are fewest, or almost wanting, on the 
