EPIDERMAL APPENDAGES, 331 



and described in the Phil. Trans, for 1747, vol. xl. ; as also 

 of lizards 'slipping off their skins as vipers do.' Some young 

 vipers changed at six weeks old, and again in two months 

 after that. 'They always began at the mouth/ said the 

 writer. The process has been witnessed and described by 

 many since that, though more by foreign than by English 

 naturalists. 



Some of the older writers have told us that ' a snake 

 frequents the spot where it has cast its skin,' or, in other 

 words, that it selects that locality for its nest — a fact as 

 curiously stated as if you related of a person that he chose 

 for his home the house in which he performed his toilet. 

 Snakes have a strong affection for locality ; and where 

 their nest is, there, or near it, their garments are naturally 

 renewed. 



Another mooted question has been the precise period 

 of sloughing ; formerly the accepted opinion was that once 

 a year, viz. in the spring, was the usual habit. This was 

 probably from so many coils of skins being found at this 

 season. That they do change in the spring may be estab- 

 lished as an almost invariable rule ; but not then only. No 

 precise periods can be given with certainty, because it 

 depends on the individual, its health and surroundings. The 

 ophidian is a fastidious creature, and when his garment 

 becomes soiled or uncomfortable he discards it. Thus after 

 hibernation, when for some months numbers of snakes have 

 been coiled in masses in a cave or under stones and rubbish, 

 and they emerge into daylight, aroused by the sun's revivify- 

 ing rays, what more natural than to cast off the old winter 

 garb for a more comfortable suit ? 



