CHAP. XIX THE MADAGASCAR GROUP 431 



moving lizards, especially abundant in Madagascar, from 

 which no less than eighteen species are now known, 

 about the same number as on the continent of Africa. 

 The Seychelles species {Chamceleoii tigris) also occurs at 

 Zanzibar. The next are skinks (Scincidse), small gTound- 

 lizairds with a wide distribution in the Eastern hemi- 

 sphere. Two species are however peculiar to the islands 

 — Mctbuia seycJiellensis and 31. lurigJitii. The other 

 peculiar species is one of the geckoes (Geckotidjs) named 

 JEluronyx seycJiellensis, and thei'e are also three other 

 geckoes, Phelsitmct madagascarensis, Gehyra mutilata and 

 Hcriiidaetylus frenatus, the two latter having a wide 

 distribution in the tropical regions of both hemispheres. 

 These lizards, clinging as they do to trees and timber, are 

 exceedingly liable to be carried in ships from one country 

 to another, and I am told by Dr. Giinther that some are 

 found almost every year in the London Docks. It is 

 therefore j^robable, that when species of this family have a 

 very wide range they have been assisted in their migrations 

 by man, though their habit of clinging to trees also renders 

 them likely to be floated with large pieces of timber to 

 considerable distances. Dr. Percival Wright, to whom I 

 am indebted for much information on the productions 

 of the Seychelles Archipelago, informs me that the last- 

 named species varies greatly in colour in the different 

 islands, so that he could always tell from which particular 

 island a specimen had been brought. This is analogous to 

 the curious fact of certain lizards on the small islands in 

 the Mediterranean being always very different in colour 

 from those of the mainland, usually becoming rich blue or 

 black (see Nature, Vol. XIX. p. 97) ; and we thus learn 

 how readily in some cases differences of colour are brought 

 about, either directly or indirectly, by local conditions. 



Snakes, as is usually the case in small or remote islands, 

 are far less numerous than lizards, only two species being 

 known. One, Dromieus seycJiellensis, is a peculiar species 

 of the family Colubridae, the rest of the genus being found 

 in Madagascar and South America. The other, Boodon 

 geomctriens, one of the Lycodontid^, or fanged ground- 

 snakes, is also joeculiar. So far, then, as the reptiles are 



