BIRDS. 481 



it is also doubtful whether if beneficial f ,iey would often be 

 preserved through selection and transmitted to succeeding 

 generations.* Nevertheless, it may be worth while to give 

 the few cases which I have been able to collect, relating 

 chiefly to color simple albinism and melanism being 

 excluded. Mr. Gould is well known to admit the exist- 

 ence of few varieties, for he esteems very slight differences 

 as specific; yet he statesf that near Bogota certain hum- 

 ming-birds belonging to the genus Cynanthus are divided 

 into two or three races or varieties, which differ from each 

 other in the coloring of the tail " some having the whole of 

 the feathers blue, while others have the eight central ones 

 tipped with beautiful green." It does not appear that 

 intermediate gradations have been observed in this or the 

 following cases. In the males, alone of one of the Austra- 

 lian paroquets " the thighs in some are scarlet, in others 

 grass-green." In another paroquet of the same country 

 " some individuals have the band across the wing-coverts 

 bright yellow, while in others the same part is tinged with 

 red."J In the United States some few of the males of the 

 Scarlet Tanager (Tanagra rubra) have "a beautiful trans- 

 verse band of glowing red on the smaller wing-coverts ;" 

 but this variation seems to be somewhat rare, so that its 

 preservation through sexual selection would follow only 

 under unusually favorable circumstances. In Bengal the 

 honey buzzard (Pernis cristata) has either a small rudi- 



*" Origin of Species," 5tli edit., 1869, p. 104. I had always per- 

 ceived that rare and strongly marked deviations of structure, deserv- 

 ing to be called monstrosities, could seldom be preserved through 

 natural selection, and that the preservation of even highly beneficial 

 variations would depend to a certain extent on chance. 1 had also 

 fully appreciated the importance of mere individual differences, and 

 this led me to insist so strongly on the importance of that unconscious 

 form of selection by man which follows from the preservation of the 

 most valued individuals of each breed, without any intention on his 

 part to modify the characters of the breed. But until I read an able 

 Article in the " North British Review " (March, 1867, p. 289, etseq.), 

 which has been of more use to me than any other review, I did not 

 "See how great the chances were against the preservation of variations, 

 whether slight or strongly pronounced, occurring only in single 

 individuals. 



f " Introduct. to the Trochilidae," p, 102. 



j: (lould, " Hand-book to Birds of Australia," vol. ii, pp. 32, 68. 



;i Audubon. " OrnUholog. Biography," 1838, vol. iv, p. 389. 



