BIBBS. 4^5 



young male. In the male Merganser the enlarged portion 

 of the trachea is furnished with an additional pair of mus- 

 cles.* In one of the ducks, however, namely. Anas 

 punctata, the bony enlargement is only a little more devel- 

 oped in the male than in the female, f But the meaning 

 of these differences in the trachea of the two sexes of the 

 Anatidae is not understood ; for the male is not always the 

 more vociferous; thus with the common duck, the male 

 hisses, while the female utters a loud quack. | In both 

 sexes of one of the cranes ( Grus virgo) the trachea pene- 

 trates the sternum, but presents " certain sexual modifica- 

 tions." In the male of the black stork there is also a well- 

 marked sexual difference in the length and curvature of the 

 bronchi. Highly important structures have, therefore, in 

 these cases been modified according to sex. 



It is often difficult to conjecture whether the many 

 strange cries and notes uttered by male birds during the 

 breeding-season serve as a charm or merely as a call to the 

 female. The soft cooing of the turtle-dove and of many 

 pigeons, it may be presumed, pleases the female. When the 

 female of the wild turkey utters her call in the morning, the 

 male answers by a note which differs from the gobbling 

 noise made, when with erected feathers, rustling wings and 

 distended wattles, he puffs and struts before her. || The 

 spel of the black-cock certainly serves as a call to the 

 female, for it has been known to bring four or five females 

 from a distance to a male under confinement; but as the 

 black-cock continues his spel for hours during successive 

 days, and in the case of the capercailzie " with an agony 

 of passion," we are led to suppose that the females which 

 are present are thus charmed.il The voice of the common 



Bishop, in Todd's " Cyclop, of Anat. and Phys.," vol. iv, p. 1499. 



f Prof. Newton, " Proc. Zoolog. Soc.," 1871, p. 651. 



X The spoonbill (Platalea) has its trachea convoluted into a figure 

 of eight, and yet this bird (Jerdon, " Birds of India," vol. iii, p. 763) 

 is mute; but Mr. Blyth informs me that the convolutions are not 

 constantly present, so that perhaps they are now tending toward 

 abortion. 



'* Elements of Comp. Anat.," by R. Wagner, Eng. translat., 1845, 

 p. 111. With respect to the swan, as given above, Tarrell's "Hist, 

 of British Birds," 2d edit, 1845, vol. iii, p. 193. 



I C. L. Bonaparte, quoted in the " Naturalist Library; Birds," vol. 

 xiv, p. 126. 



^L. Lloyd, " The Game Birds of Sweden," etc., 1867, pp. 22, 81. 



