320 CHARADRIIFORMES CHAP, 



ranges from the Gulf of St. Lawrence and Iceland to the Arctic 

 Seas of both worlds in summer, moving further south in winter ; 

 the North Pacific race being denominated U. arra. Descriptions 

 of the colonies of Guillemots in the icy seas, and of the smaller but 

 equally crowded stations in Britain, have been too frequently 

 given to need repetition here; but it may be mentioned that 

 during incubation, which lasts about a month, the parent holds 

 the egg between its thighs, and not unfrequently carries it off 



FIG. 64. Great Auk. Alca impennis. x . (After Hancock.) 



a ledge, when suddenly scared. On flat-topped stacks these eggs 

 (p. 316) often lie in the closest juxtaposition. 



In Alca the black bill is deep and highly compressed, with a 

 curved culmen; and shews oblique or transverse grooves, which are 

 wanting in the young. A. torda, the Eazorbill, less common in 

 Britain than the Guillemot, ranges from Jan Mayen and Greenland 

 to Maine and Brittany, visiting North Carolina and the Canaries 

 in some winters. It is greenish-black with brown throat-region 

 and white lower parts, a white line stretching from the top of the 



