390 GALAPAGOS ARCHIPELAGO. [chap. xvii. 



These two species of Amblyrhynchus agree, as I have already- 

 stated, in their general structure, and in many of their habits. 

 Neither have that rapid movement, so characteristic of the genera 

 Lacerta and Iguana. They are both herbivorous, although the 

 kind of vegetation on which they feed is so very different. Mr. 

 Bell has given the name to the genus from the shortness of the 

 snout; indeed, the form of the mouth may almost be compared 

 to that of the tortoise : one is led to suppose that this is an 

 adaptation to their herbivorous appetites. It is very interesting 

 thus to find a well-characterized genus, having its marine and 

 terrestrial species, belonging to so confined a portion of the 

 world. The aquatic species is by far the most remarkable, be- 

 cause it is the only existing lizard which lives on marine vege- 

 table productions. As I at first observed, these islands are not 

 so remarkable for the number of the species of reptiles, as for 

 that of the individuals ; when we remember the well-beaten paths 

 made by the thousands of huge tortoises — the many turtles — the 

 great warrens of the terrestrial Amblyrhynchus — and the groui)s 

 of the marine species basking on the coast-ro(;ks of every island 

 — we must admit that there is no other quarter of the world 

 where this Order replaces the herbivorous mammalia in so extra- 

 ordinary a manner. The geologist on hearing this will probably 

 refer back in his mind to the Secondary epochs, when lizards, some 

 herbivorous, some carnivorous, and of dimensions comparable only 

 with our existing whales, swarmed on the land and in the sea. It 

 is, therefore, worthy of his observation, that this archipelago, in- 

 stead of possessing a humid climate and rank vegetation, cannot 

 be considered otherwise than extremely arid, and, for an equa- 

 torial region, remarkably temperate. 



To finish with the zoology ; the fifteen kinds of sea-fish which 

 I procured here are all new species ; they belong to twelve ge- 

 nera, all widely distributed, with the exception of Prionotus, of 

 which the four previously known species live on the eastern side 

 of America. Of land-shells I collected sixteen kinds (and two 

 marked varieties), of which, with the exception of one Helix 

 found at Tahiti, all are peculiar to this archipelago : a single 

 fresh -w^ater shell (Paludina) is common to Tahiti and Van Die- 

 men's Land. Mr. Cuming, before our voyage, procured here 

 ninety species of sea-shells, and this does not include several 



