oiiAr. XIX.] 



THE MADAGASCAB GEOUP. 



4C'3 



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 m.ainlaDd, 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 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, Broinims seychellensis, is a peculiar species of the family 

 Colubridse, the rest of the' genus being found in Madagascar and 

 South America. The other, Boodon geometrims, one of the 

 Lycodontidse, or fanged ground-snakes, inhabits also South and 

 West Africa. So far, then, as the reptiles are concerned, there is 

 nothing but what is easily explicable by what we know of the 

 general means of distribution of these animals. 



We now come to the Amphibia, which are represented in the 

 Seychelles by two tailless and two serpent-like forms. The frogs 

 are, Rana mascariensis, found also in Mauritius, Bourbon, An- 

 gola, and Abyssinia, and probably all over tropical Africa ; and 

 Megalixalus infrariifus, a tree-frog altogether peculiar to the 

 islands, and forming a peculiar genus of the widespread tropical 

 family Polypedatidse. It is found, Dr. Wright informs me, on 

 the Pandani or screw-pines ; and as these form a very character- 

 istic portion of the vegetation of the Mascarene Islands, all 

 the species being peculiar and confined each to a single island 

 or small group, we may perhaps consider it as a relic of the 

 indigenous fauna of that m^ore extensive land of which the 

 present islands are the remains. 



The serpentine Amphibia are represented by two species of 

 Caecilia. These creatures externally resemble large worms, 

 except that they have a true head with jaws and rudimentary 

 eyes, while internally they have of course a true vertebrate 

 skeleton. They live underground, burrowing by means of the 

 ring-like folds of the skin which simulate the jointed segments 

 of a worm's body, and when caught they exude a viscid slime. 

 The young have external gills which are afterwards replaced by 



