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 of Man (see vol. ii., p. 187, and onwards). 



Weissmann's Essays on Heredity (see p. 1 1 and onwards). 



Professor W. K. Parker on the " Morphology of Opisthocomus 

 Cristatus," Transactions of the Zoological Society, vol. xiii., 

 part 2. 



Mr. J. J. Ouelch on the " Habits of the Hoatzin," Ibis, vol. 

 ii., 1890, p. 327. 



Mr. W. P. Pycraft on " The Wing of Archaeopteryx," Nat. 

 Science, Nov. 1894. 



(I am also indebted to Mr. C. M. Adamson's Some more 

 Scraps about Birds, printed for private circulation.) 



