2006 Thk Zoologist— February, 1870. 



excavated for the purpose. Auks are all altrices, and are believed to 

 be chiefly monogamous. The young are at first covered with long 

 soft woolly down ; rarely stiffish hairs appear on some parts. The 

 moult is double. The young of the year usually differ from the 

 adults ; the latter usually differ iu their summer and winter plumages. 

 A very prevalent feature is the possession of crests or |)liimes, or 

 elongated feathers of a peculiar shape on the sides of the head. All 

 the species walk badly; some scarcely walk a( all. The position of 

 the legs with reference to the axis of the body necessitates an upright 

 position when standing. The birds appear to rest on their rumps, 

 with the feet extended horizontally before them, most of the tarsus 

 touching the ground. The puffins, however, and a few. others, stand 

 well on their feet. All the species but one fly well, with rapid 

 vigorous motion of the wings, in a straight, firm, well-sustained course. 

 All progress on or under the water with the utmost facility. They are 

 very .silent birds ; the voice is rough and harsh ; the notes are mono- 

 toned. They feed exclusively upon animal substances procured from 

 the water. 



The uniformity of structure which obtains throughout the family 

 has already been mentioned : the following paragraphs describe this 

 structure in a general way, so far as the details of external form are 

 concerned : * 



The general form is stout, compact and heavy. The body is 

 depressed, flattened underneath. The neck is short and thick. Tlie 

 head is large and heavy, usually oval in shape, more or less flattened 

 laterally, more or less drawn out anteriorly, and sloping gradually on 

 all sides to the bill, but sometimes ending abruptly. The plumage 

 about the head is very soft, dense, and short, except those feathers 

 which constitute the peculiar crest or lateral plumes already mentioned. 

 That of the upper parts is very closely imbricated ; that of the lower 

 is very thick, compact, elastic and otherwise eminently fitted to resist 

 the action of water.f 



The bill, though constantly preserving certain characteristics, varies 

 to a remarkable degree in the details of its shape. The broad state- 

 ment may be made, that no two species J of the family have bills 

 identical in shape. So unending is the variation in the bill, that in 



* The writer hopes to bring forward, at some future lime, a memoir on the 

 an.Ttoniy of tlie family. 



t Cf. Nitzsch's Plerjlofirapby for pierylosis of Ulamania torda. 

 J Is Uria riiigvia specifically dislinct from U. troile? 



