66 REPTILES 



is developed for the purpose of aiding in the shedding of the 

 scales, and acts physiologically by accelerating lymph-move- 

 ments, and thus promoting metabolism, and mechanically by 

 stretching the skin over the soft parts. This being so, the 

 probability is that the same factor holds good in the case of 

 snakes and tortoises ; but in some instances the function may 

 be modified for terrifying or sexual purposes, and it is probable 

 that the ejection of blood from the eyes of the " horned toads " 

 {Phrynosomd) is a development of the same mechanism. 



From the foregoing it is clear that it is necessary to be 

 guarded in framing any hypothesis as to the precise significance 

 of brilliant coloration among reptiles. Though commonly as- 

 sociated with sexual display, it does not seem always to be used 

 as an accessory in this respect. 



A case in point is furnished by the painted terrapin {Chrys- 

 emys picta). In the breeding season the male has been seen 

 dodging the female, and making efforts to oppose her path. 

 This end accomplished, the male closed up and immediately 

 commenced to beat a lively tattoo with his long finger-nails 

 upon her head and eyes, the movements being so rapid that 

 nothing more than a blurred image was possible. So soon as 

 possible, the female escaped these attentions, when the male 

 set about repeating the performances, which were witnessed not 

 once but many times before the pair were disturbed and made 

 off. Here no use seems to have been made of the bright 

 coloration but only one phase of the "display" may have been 

 observed. 



Crocodiles find a sombre livery useful, since it affords con- 

 cealment. Consequently the males present, except in the case 

 of the gharial, no ornamental colours, nor any other marked 

 secondary sexual character. Nevertheless, alligators, when en- 

 deavouring to attract the females, splash, roar, and twist them- 

 selves around on the water, with the head and tail raised, and 

 the body inflated to its utmost extent, the effect of this 

 being increased by the emission of a strong odour of musk from 

 glands in the lower jaw. 



In many lizards the males display great pugnacity during 

 the breeding season, and rivals never meet without a conflict. 

 In Anolis carolinensis \ for example, when two males meet they 

 face one another, bob the head up and down two or three times 



