REPTILES. 347 



lowing 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 butting -against each other."" 



Crocodil'la.- — 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. Bar- 

 tram" 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 spins 

 "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 submaxillary glands of the crocodile, and 

 pervades their haunts.^' 



Ophidia. — Dr. Gtinther 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 dis- 

 tinctly defined than in the female. The difference is much plainer 

 in the rattle-snakes of N. America, the male of which, as the 

 keeper in the Zoological Gardens showed me, can at once be dis- 

 tinguished from the female by having more lurid yellow about its 

 whole body. In S. Africa the Bucephalus capensls 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, on the other hand, is blackish-brown, with the 

 belly partly black, whilst the female is reddish or yellowish-olive, 

 with the belly either uniform yellowish or marbled with black. 

 In the Tragops dispar of the same country, the male is bright 

 green, and the female bronze-colored." No doubt the colors of 

 some snakes are protective, as shown by the green tints of tree- 

 snakes, and the various mottled shades of the species which live in 

 sandy places; but it is doubtful whether the colors of many kinds, 

 for instance of the common English snake and viper, serve to 



"^ See my 'Journal of Researches During the Voyage of the "Bea- 

 "gle," ' 1845, p. 384. 

 ^ Dr. Gunther, 'Reptiles of British India,' 1864, p. 7. 

 M 'Travels through Carolina,' &c., 1791, p. 128. 

 =5 Owen, 'Anatomy of Vertebrates,' vol. i. 1866, p. 615. 

 =» Sir Andrew Smith, 'Zoolog. of S. Africa: Reptilia,' 1849, pi. x. 

 " Dr. A. Gunther, 'Reptiles of British India,' Ray Soc. 1864, pp. 304, 308. 



