Ix YOUTH, MATURITY, AND AGE 293 
life; (2) his late attainment of maturity; (3) the 
high death-rate among the young. The ages to 
which birds may attain are as a rule but vaguely 
known. Our small singing birds sometimes live to be 
ten years old; a Magpie has lived twenty years in 
captivity, Parrots upwards of 100. Humboldt’s story 
of a Parrot, whose words the Indians said could not be 
understood because it spoke the language of an ex- 
tinct tribe, is an amusing myth sprung from an old 
belief. Some idea of the age attained by Guillemots, 
Razorbills, and Puffins may be formed from the fact 
that they lay only one egg, and, though the young are 
exposed to great dangers, yet the numbers of the 
species do not diminish. Even if they sometimes have 
two nests in the year, yet unless their span of life were 
a fairly long one they could not keep up their numbers. 
Ravens have lived nearly 200 years in captivity, and a 
White-headed Vulture captured in 1706 is believed to 
have’ died at the Zoological Gardens at Vienna in 
1824. 
LITERATURE BEARING ON THE SUBJECT. 
Darwin’s Descent af Man (see vol. ii., p. 187, and onwards). 
Weissmann's Essays on Heredity (see p. 11 and onwards). 
Professor W. K. Parker on the “ Morphology of Opisthocomus 
Cristatus,” Transactions of the Zoological Socdety, vol. xiii., 
art 2. 
: Mr. J. J. Quelch on the “Habits of the Hoatzin,” /é7s, vol. 
ii., 1890, p. 327. 
Mr. W. P. Pycraft on “The Wing of Archzopteryx,” Mad. 
Science, Nov. 1894. 
(I am also indebted to Mr. C. M. Adamson’s Some more 
Scraps about Birds, prmted for private circulation.) 
