486 COLTMBID.TC. 



1. COLYMBUS.* rv 



Type. 



Mergus, Brisson, Orn. vi. p. 104 (1760) C. glacialis. 



Colymbus, Linn. S. N. i. p. 220 (1766) 0. septentiionalis. 



PGavia, Forst., Enchirid. Rist. Nat. p. 38 (1788). No type. 

 Urinator, Lacep. in Btiff. Hist. Nat. (ISrao, Didot) 



Quad): xiv. p. 310 (1799) ; Cuv. Anat. Comp. 



i. Table 2 (1800) C. glacialis. 



Eudytes, Illiyer, I'rudromus, p. 282 (1811) C. seplentrionalis. 



Bill stout, straight, compressed, tapering to a sharp point ; nostrils 

 linear ; wing composed of long stiff quills, the 1st and 2nd sub- 

 equal, and slightly the longest; tail composed of IS or 20 short 

 stiff feathers ; legs placed far back ; tarso-metatarsi short and 

 laterally compressed ; front toes imited one to the other by a web 

 the fourth or outer toe being the longest ; hind toe or halluxon 

 the same plane as the rest. 



Range. Circumpolar. 



Key to the Species. 

 Summer plumage. 



I. A triangular patch of vinaceous chestnut at 



the base of the fore-neck septenivionalis, p. 487. 



II. Fore-neck purplish or greenish black. 



A. Head and back of neck grey or whitish ash ; 



size smaller; wing 11-5-13 inches. 



a. Nape and hind-neck dove-grey arcticus, p. 492. 



b. Nape and hind-neck dirty white or whitish 



ash pacificMS, p. 494. 



B. Head and back of neck black : size larger, 



wing M-l^) inches. 



c. Bill black ; ridge of culmen sliglitly con- 



vex, angle of genys indistinct glacialis, p. 496. 



d. Bill whitish or yellowish ; culmen almost 



straight, angle of genys strongly marked adamsi, p. 500. 



Winter plumage. 



I. Upper parts dark ash-brown, spotted with 



white scpientrionalis, p. 487. 



II. Upper parts uniform dark ash-brown ; wing- 



coverts more or less spotted with white ; f arcticus, p. 492. 

 size smaller, wing 11*5-13 inches \pacificus, p. 494. 



* The foUowiug works refer to the anatomy, etc. of the group : — Coues, 

 P. Acad. Pbilad. 1S61, pp. 21-22 [crania of C. glacialis and C. adamsi'] ; id, 

 Mem. Best. See. N. H. i. pt. ii. pp. 131-172, pi. v. (1867) [osteology and myo- 

 logy of C. glacialis] ; Eyton, Osteol. Av. p. 213, pi. 1 L. pi. xl. fig. 2 (1867) ^ 

 Nitzsch, Pteryl., Engl. ed. p. 152, pi. x. figs. 10, 11 (18()7) ; Garroci, P. Z. S. 

 1873, p. 470 [both carotids present in C. glacialis], p. 642 [muscles] ; Sundev. 

 Ibis, 1886, pp. 425, 4.57 [wiug] ; Shufeldt, P. U.S. Nat. Mus. s. p. 377 (1887) 

 [anatomy of C. scptentriomdis] ; Beddard, P. Z. S. 1890, pp. 430-442 [general 

 remarks] ; Shufeldt, J. Anat. Phys. xxiv. pp. 169-187, pis. xi., xii. (1890), xxvi. 

 pp. 199-203 (1892) ; Mitchell, P. Z. S. 1896, p. 143 [note on intestinal tract] ; 

 Beddard, P. Z. S. 1897, p. 468 [intercentra in C. scptentrionalis] ; Shufeldt, 

 Ibis, 1898, pp. 46-51 [terrestrial attitudes]. 



