1060 



SYSTEMA TIC SYNOPSIS. — PYGOPODES — ALC.E. 



dated in 1877 and 1879 by - ' 



L. Bureau, who showed 

 that in certain species parts of tlie horny 

 covering are regukirly shed or moulted, in 

 a manner anahtgous to tlie casting of deer's ant- 

 lers, and quite as in tlie case of our White Peli- 

 can, which drops the "centre-board" of the 

 l)iil. In the Common Puffin, for example, no 

 fewer than nine horny pieces fall off separately, 

 after the breeding season, to be renewed again 

 from the soft basement membrane. The ab- 

 sence, in winter, of the horny plate at the angle 

 of the mouth of Simorliynchus cristatellus, had 

 been noted (Key, 1872), as well as the presence 

 or absence of the horn of Ceratorhina ; but we 

 had no knowledge of the process by which the 

 change is effected, prior to Bureau's studies. 

 Since then Simorhynchus pusillus has proved 

 to shed the knob. In Fratercula there is also 

 a moult of the excrescences upon the eyelids, 

 and a shrivelling of the colored rosette at tlie 

 corner of the mouth. 



Auks are confined to the Northern Hemi- 

 sphere. Some representatives have been found 

 as far north as explorers have penetrated, but the 

 great majority live in more temperate latitudes. 

 A more or less complete migration takes place 

 wath most species, which stray southward, some- 

 times to a considerable distance, in autumn, 

 and return north again to breed in spring; a 

 few appear nearly stationary. The most south- 

 ern accredited habitat of any member of tlie 

 family is about latitude 20° N., on the Pacific 

 coast of North America, but this is exceptional. 

 The species are very unequally divided between 

 the two oceans, the Atlantic having but few rep- 

 resentatives compared with the Pacific. On the 

 northern coasts of the latter the family reaches 

 its highest development ; the greatest number Kittiwakes (p. 993), Auks, etc. (Designed by H. W. 



nf or.o«;/:>o .,.->rl ^^v,.,-, ^ e J »i ^1 1 Elliott. (From Harper Brothers.) 



or species and genera are found there, though 



the number of individuals of no species surpasses that of several Atlantic representatives. 



Fig. 715. — Egging in Alaska on cliff.s inli.-ibited by 



