COLYMBUS AECTICUS, BLACK-THROATED DIVER. 721 



oulnien convex ; commissure somewhat decurvecl ; gouys convex, with slight angle. 

 Frontal anti;;' falling short of middle of nostrils. Gloss of head and neck mostlj' greeu. 

 White sjjots of back nearly sqnare. 



Car. ADAMSii: Cnlmeu, about 3.75; gape, abont 5; height of bill at nostrils, aver- 

 age, over 1. Bill along culnieu longer than tarsus. Color of bill mostly yellow ; its 

 culmen nearly straight ; commissure straight; gonys straight, with prominent angle. 

 Frontal antitu reaching middle of nostrils. Gloss of head and neck mostly blue. White 

 spots of back longer than broad. 



The tyi)e of this form was from Russian America, now Alaska. Numer- 

 ous specimens in breeding i)litmage have been received at the Smith- 

 sonian from various parts of Arctic America. The form appears to have 

 been also lecorded in Asia, and is even quoted from England. I have 

 seen no United States examples : nor have I recognized the bird in its 

 young plumage, when, probably, it could not be distinguished with any 

 certainty from ordinary torquatus. Specimens are labeled as having 

 the iris light reddish-brown, the feet olivaceous. 



Notwithstanding the distinctions in the size, shape, and color of the 

 bill, I am now rating this bird as a variety of torqtiatns, being satis- 

 Hed that the characters iutergrade with those of the latter. 



COLYMBUS AR(3TICUS, Linn. 

 Bladi-throated Diver. 



a. arcticiis. 



Cohjmliis arciicHS, LiNX., Svst. Nat. i, 1766, 221.— Gm., Svst. Nat. i, 1788, 587.— Lath., 

 Lid. Orn. ii, 17U0, 8U0.— Bi;UNN., Orn. Bor. 1764, No. 133.— Temm., Man. Oru. 

 1815, 599.— Stkpii., Gen. Zool. xii, 1824, 236.— Keys. & Blas., Wirb. Eur. 1840, 

 91.— GitAY, Gen. of B. iii, 631, pi. 171.— SuxD., Svensk. Fogl. pi. 53.— Bp., Syn. 

 1828, 420; List, 1838, 65— Aud., Oru. Biog. iv, 1838, 345, pi. 346; Syn. 1839, 

 354 ; B. Am. vii, 1844. 29.5, pi. 477.— Nutt., Man. ii, 1834, 517.— Sw. & Rich., F. 

 B. A. ii, 1831, 475.— Lawk., B. N. A. 1858. 888; Ann. Lye. N. Y. viii, 1866, 300 

 (New York).— CouKS, Pr. Phila. Acad. 1862, 228.— Coues, Pr. Ess. Inst, v, 1868, 

 309 (New England),— Dall Sc Bann., Tr. Chic. Acad. 1869, 307 (Alaska).— 

 FiNScn, Abh. Nat. iii, 1872, 74 (Alaska).— Coues, Key, 1872, 334.— Coues, Elli- 

 ott's Prybilov Islands, 1874.— Ridgw., x\nn. Lye. N. Y. x, 1874, 392 (Illinois) ; 

 and of authors generally. 



Ccpplius arcticiiH, Pale., Zoog. R.-A. ii, 1811, 91. 



Eudytcs «>t7(cH.s, III., Piod. 1811, 282.— Nalm., V. D. xii, 1844, 418, pi. 328. 



Cohimhun mnvrorlnpuhos, Bkeiim, V. D. 1831, 974. 



Coiipnhun miiiarhipichoK, Bi;EiiM, Naum. v, 1855, 300 ; V. D. 974. 



Cohjmhus hallhicuit, IIoknscie, Verz. Pommersch. Vog. 21. 



" Cohjmhus ignotu8 et leucojius, Bechst., Naturg. iv, 782." 



b. 2)c(cijictis. 



Cohimhus imnfwns, Lawi:., B. N. A. 1858. 889.- Coues, Pr. Pliila. Acad. 1862, 228.— CodP. 



& Suck., N. H. Wash. Ter. 1860, 279.— Coues, Ibis, 1866, 273 (Southern Cali- 



foruia).— CouES, I'r. Phila. Acad. 1866, 100. 

 Colymbtta arclicus var. imdjicus, Coues, Key, 1872, 335. 



Ilah. — The Northern hemisphere. Var. pacificus from the Pacific coast of North 

 America. 



This species, which was not noticed by either of the Expeditions, appears to be a 

 more northerly bird than the last, and, according to my experience, it is rare in the 

 United States. Audulton, however, states that it comes as far south as Texas. The 

 Pacific variety is u common bird on the coast of California in winter. 



Vdr. ARCTicus: BUal; -throated Diver. 



CiiAi:. Bill generally as in l(n<iii(ilii>i, but smaller; color black. Chin, throat, and 

 neck in front, i)lack, with purplisli and vicdet n^llections on the sidi-sof the head, grad- 

 ually fading into a fine, char bluish-gray, deepest on the forehead, lighest behiutl, and 

 separated Irom the Idack of the throat l)y a si'ries of white streaks. A cri'seent of .short, 

 white stieaks across upper throat; sides of breast striped with pure white aud glossy 



4G 



