Chap. XIL] REPMLES. 35 



pale grayish-green without spots." " We have seen that 

 the males alone of Sitana possess a throat-pouch ; and this 

 is splendidly tinted with "blue, black, and red. In the 

 Proctotretus tenuis of Chili the male alone is marked with 

 spots of blue, green, and coppery-red. 68 I collected in 

 South America fourteen species of this genus, and though 

 I neglected to record the sexes, I observed that certain 

 individuals alone were marked with emerald-like green 

 spots, while others had orange-colored gorges ; and these 

 in both cases no doubt were the males. 



In the foregoing species, the males are more brightly 

 colored than the females, but with many lizards both 

 sexes are colored in the same elegant or even magnificent 

 manner; and there is no reason to suppose that such con- 

 spicuous colors are protective. With some lizards, how- 

 ever, the green tints no doubt serve for concealment ; and 

 an instance has already been incidently given of one 

 species of Proctotretus which closely resembles the sand 

 on which it lives. On the whole we may conclude with 

 tolerable safety that the beautiful colors of many lizards, 

 as well as various appendages and other strange modi- 

 fications of structure, have been gained by the males 

 through sexual selection for the sake of ornament, and 

 have been transmitted either to their male offspring alone 

 or to both sexes. Sexual selection, indeed, seems to have 

 played almost as important a part with reptiles as with 

 birds. But the less conspicuous colors of the females in 

 comparison with those of the males cannot be accounted 

 for, as Mr. Wallace believes to be the case with birds, by 

 the exposure of the females to danger during incubation. 



57 Bell, ' History of British Reptiles,' 2d edit. 1849, p. 40. 



68 For Proctotretus see * Zoology of the Voyage of the " Beagle : " 

 Keptiles,' by Mr. Bell, p. 8. For the Lizards of South Africa, see ' Zool- 

 ogy of South Africa: Reptiles,' by Sir Andrew Smith, pis. 25, 39. 

 For the Indian Calotes, see ' Reptiles of British India,' by Dr. Guntber, 

 p. 143. 



