404 CHARLES DARWIN 



plants, and insects have a desert character, and are not more 

 brilliantly coloured than those from southern Patagonia; we 

 may, therefore, conclude that the usual gaudy colouring of 

 the inter-tropical productions, is not related either to the 

 heat or light of those zones, but to some other cause, per- 

 haps to the conditions of existence being generally favour- 

 able to life. 



We will now turn to the order of reptiles, which gives 

 the most striking character to the zoology of these islands. 

 The species are not numerous, but the numbers of individ- 

 uals of each species are extraordinarily great. There is one 

 small lizard belonging to a South American genus, and two 

 species (and probably more) of the Amblyrhynchus a genus 

 confined to the Galapagos Islands. There is one snake which 

 is numerous ; it is identical, as I am informed by M. Bibron, 

 with the Psammophis Temminckii from Chile.* Of sea- 

 turtle I believe there are more than one species; and of tor- 

 toises there are, as we shall presently show, two or three 

 species or races. Of toads and frogs there are none: I was 

 surprised at this, considering how well suited for them the 

 temperate and damp upper woods appeared to be. It re- 

 called to my mind the remark made by Bory St. Vincent,* 

 namely, that none of this family are found on any of the vol- 

 canic islands in the great oceans. As far as I can ascertain 

 from various works, this seems to hold good throughout the 

 Pacific, and even in the large islands of the Sandwich archi- 

 pelago. Mauritius offers an apparent exception, where I 

 saw the Rana Mascariensis in abundance: this frog is said 

 now to inhabit the Seychelles, Madagascar, and Bourbon; 

 but on the other hand, Du Bois, in his voyage in 1669, states 

 that there were no reptiles in Bourbon except tortoises ; and 

 the Officier du Roi aserts that before 1768 it had been at- 

 tempted, without success, to introduce frogs into Mauritius 

 I presume for the purpose of eating : hence it may be well 



3 This is stated by Dr. Gunther (Zoolog. Soc., Jan 24th, 1859) to be a 

 peculiar species, not known to inhabit any other country. 



3 Voyage aux Quatre lies d'Afrique. With respect to the Sandwich 

 Islands, see Tyerman and Bennett's Journal, vol. i. p. 434. For Mauritius, 

 see Voyage par un Officier, etc., part i. p. 170. There are no frogs in the 

 Canary Islands (Webb et Berthelot, Hist. Nat. des lies Canaries). I saw 

 none at St. Jago in the Cape de Verds. There are none at St. Helena. 



