ALCIB^: AUKS. 



799 



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 

 stifBsh hairs appear on some parts. 

 The moult is double. The young 

 of the year usually diflfer from the 

 adults ; the latter usually differ in 

 their summer and winter plumages. 

 A very prevalent feature is the 

 ( issession of crests or plumes, or 

 bngated feathers of a peculiar 

 1 ape on the sides of the head. 

 All the species walk badly; 

 some scarcely walk at 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, how- 

 ever, 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 monotoned. 

 They feed exclusively upon 

 animal substances procured 

 fi-om the water. 



The family is divisible into two subfamilies according to the feathering of the nostrils 

 and other characters. 



Analysis of Subfamilies and Genera. 



Pbaleridiit^. Nostrila naked, remote from feathers. Bill of variable shape, always compressed, 



higher than wide, as f^ as known appendaged with deciduous elements. Head nearly always crested. 



No great seasonal changes of plumage. 



Eyelids with deciduous appendages. No crests. Bill extremely high and thin; culmen with one 



curve; both mandibles grooved. A rosette at angle of mouth. Covering of bill moulted in 7-9 



pieces. Inner lateral claw enlarged. Tarsus scutellate in fi-ont Fratercula 337 



Eyelids simple. Long lateral crests. Bill extremely high and thlni culmen with two curves; upper 

 mandible grooved, under smooth. A rosette at angle of mouth. Covering of bill moulted in " pieces 



Inner lateral claw enlarged. Tarsus scutellate in front Lunda 338 



Eyelids simple. Lateral crests. Bill with a deciduous horn at base of upper mandible. No rosette. 



Fia. 632.— A needle rock tenanted by Cormorants (p. 728, No. 757), Auks, 

 etc. (Designed by H. W. Elliott. From Harper Brothers.) 



