398 THE DESCENT OF MAN. 



are said to grow to a larger size than the females. During 

 the pairing season, and at no other time, the male utters a 

 hoarse, bellowing noise which can be heard at the distance 

 of more than a hundred yards; the female, on the other 

 hand, never uses her voice.* 



With the Testudo elegans of India it is said " that the 

 combats of the males may be heard at some distance from 

 the noise they produce in butfcing against each other. "f 



Crocodilia. The sexes apparently do not differ in color; 

 nor do I know that the males fight together, though this 

 is probable, for some kinds make a prodigious display 

 before the females. BartramJ describes the male alligator 

 as striving to win the female by splashing and roaring in 

 the midst of a lagoon, "swollen to an extent ready to 

 burst, with its head and tail lifted up, he springs or twirls 

 round on the surface of the water like an Indian chief 

 rehearsing his feats of war." During the season of love a 

 musky odor is emitted by the submaxiliary glands of the 

 crocodile and pervades their haunts. 



OpMdia. Dr. Giinther informs me that the males are 

 always smaller than the females, and generally have longer 

 and slenderer tails; but he knows of no other difference in 

 external structure. In regard to color, he can almost 

 always distinguish the male from the female by his more 

 strongly pronounced tints; thus the black zigzag band on 

 the back of the male English viper is more distinctly 

 defined than in the female. The difference is much plainer 

 in the rattlesnakes of North America, the male of which, 

 as the keeper in the Zoological Gardens showed me, can at 

 once be distinguished from the female by having more 

 lurid yellow about its whole body. In S. Africa the 

 Bucephalus capensis presents an analogous difference, for 

 the female " is never so fully variegated with yellow on the 

 sides as the male. || The male of the Indian Dipsas cynodon, 



* See my " Journal of Researches during the Voyage of the 

 'Beagle,'" 1845, p. 384. 



fDr. Giinther, " Reptiles of British India," 1864, p. 7. 

 i " Travels through Carolina," etc., 1791, p. 128. 

 0wen, " Anatomy of Vertebrates," vol. i, I860, p. 615. 

 ! Sir Andrew Smith, " Zoolog. of S. Africa: Reptilia," 1849, pi. x. 



