372 



THE DESCENT OP MAN. 



In the foregoing cases sounds are made by the aid of structures 

 already present and otherwise necessary; but in the following 

 cases certain feathers have been specially modified for the express 

 purpose of producing sounds. The drumming, bleating, neigh- 

 ing, or thundering noise (as expressed by different observers) 

 made by the common snipe (Scolopax gallinago) must have sur- 

 prised every one who has ever heai'd it. This bird, during the 

 pairing-season, flies to "perhaps a thousand feet in height," and 

 after zig-zagging about for a time descends to the earth in a 

 curved line, with outspread tail and quivering pinions, and sur- 



Fig-. 41. OuUr tail feather of Scolopax g-allinas-o (from 'Proc. Zool. 



Sec.' 1S58). 



prising velocity. The sound is emitted only during this rapid 

 descent. No one was able to explain the cause, until M. Meves 

 observed that on each side of the tail the outer feathers are 

 peculiarly formed (fig. 41), having a stiff sabre-shaped shaft, with 



Fig:. 42. 



Fig. 43. 



Outer tail-featlier of Scolo- 

 pax frenata. 



Outer tailTfeather of Scolo- 

 pax javenS'is. 



Fiff. 44. Primary wing- 

 feather of a humming-bird, 

 the Selasphcrus platycercus 

 (from a sketch by Mr. Sal- 

 vin). Upper figure, that of 

 male: lower figure, corres- 

 ponding feather of female. 



the oblique barbs of unusual length, the outer webs being strongly 

 bound together. He found that by blowing on these feathers, 

 or by fastening them to a long thin stick and waving them rap- 

 idly through the air, he could reproduce the drumming noise 



diana,' p. 227; Audubon, 'American Ornitholog. Biograph.' vol. 1. p. 216. 

 On the Kalij-pheasant, Jerdon, 'Birds of India,' vol. iii. p. 533. On the 

 AVeavers. 'Livingstone's Expedition to the Zambesi,' lS5o, p. 425. On 

 Woodpeckers, Maogillivray, 'Hist, of British Birds,' vol. iii. 1S40, pp. 

 S4, 8S, S9, and 95. On the Hoopoe Mr. Swinhoe, in Proc. Zoolog. Soc' 

 June 23. 18G3 and 1871, p. 348. On the Night-jar, Audubon, ibid. vol. il. 

 p. 255, and 'American Naturalist,' 1873, p. C72. The English Night-jar 

 likewise iriakes in the spring a cur'ous noise during its rapid flight. 



