ALCID.E — THE AUKS — ALCA. 



473 



Alca balthica, Biiunn. Orn. Bor. 1764, 25, no. 101 (immature, witliout white line from bill to eye). 



Alca unisulcata, BrU.nn. t. c. no. 102 (young). 



Alca (jlacialls, Bueh.m, Vog. Deutsclil. 18;il, 1004. 



Alca islaiulica, Bueh.m, t. c. 1005, 



Alca viicrorhyuchus, Bueh.m, Vogelt". 1855, 410. 



Hab. Coasts and islands of the North Atlantic, down to about latitude 40° in winter. Japan 

 (fide Schlegel). 



A. tarda. 



Sp. Char. Adult, in summer : Head, neck, and upper parts Idack, tlie head and neck more 

 fuliginous, and changing to soft, velvety snuil-brown on the under jjurtion of the head aiul fore- 

 neck ; secondaries narrowly tipped with white ; 

 a luirrow white line running from the base of 

 the culnien to the eye. Lower parts, including 

 juguluin, axillars, and lining of tlie wing, im- 

 maculate white. Bill black, both mandibles 

 crossed about the middle by a white line ; 

 " inside of mouth gandioge-yellow ; iris deep 

 hazel; feet black" (Audubon). Adult, in 

 ivintcr: Whole under portion of the head, fore- 

 neck, and post-auricular region white ; no white 

 line from eye to bill ; bill without basal lam- 

 ina. Otherwise like the summer plumage. 

 Youmj : Similar to the winter plumage, but 

 bill smaller, perfectly smooth, and without the 

 white bar across the middle portion. 



Total length, about 17.00 inches ; wing, 

 8.00 to 8.50; tail, 3.50 ; culmen, 1.25; great- 

 est dejjth of bill, .90 ; tarsus, 1.25 ; middle 

 toe, 1.55. 



Summer adult. 



This is a northern and Arctic species, abiunhiiit throughout the eastern shores of 

 North America from the highest latitudes to Maine in summer and to New Jersey in 

 VOL. II. — 60 



