212 ALCAD.fi, OR AUKS. 



bill black, white at the tip; the lore greyish or 

 pinkish white ; feet and legs blackish-green, paler 

 on the insides. The plumage of one shot in the 

 river Annan, in winter, is pale umber-brown, darker 

 on the wings ; on the cheeks and sides of the neck 

 there is a tint of rufous, and the chin and under 

 part are of a clear and silvery white. 



ALCAD^E, OR AUKS. 



THE birds contained in this group are entirely mari- 

 time in habit. In the preceding family we saw the 

 legs placed very far behind and the feet very ample ; 

 in the Auks we have the former structure continued, 

 with the tarsi short and the feet small, and these 

 members are not so amply developed or adapted for 

 so swift a passage through the water, nevertheless 

 the Auks are expert divers, and procure their food 

 by that means alone. They do not breed on the 

 ground, but either burrow or select precipitous rocks 

 for this purpose ; and they sit and move with ease 

 on the shelves and ledges, keeping themselves nearly 

 in an upright posture, and resting on the whole 

 posterior edge of the tarsus. The wings are short, 

 but in many are capable of a swift and rapid flight ; 

 while in a few these organs are totally unable to 

 raise the bird from the water, and act only as power- 



