4i6 GALAPAGOS ARCHIPELAGO chap. 



having its marine and terrestrial species, belonging to so con- 

 fined a portion of the world. The aquatic species is by far 

 the most remarkable, because it is the only existing lizard which 

 lives on marine vegetable 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 groups of the marine 

 species basking on the coast-rocks of every island — we must 

 admit that there is no other quarter of the world where this 

 Order replaces the herbivorous mammalia in so extraordinary 

 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, instead of possessing a humid climate and rank 

 vegetation, cannot be considered otherwise than extremely arid, 

 and, for an equatorial 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 genera, 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-water shell (Paludina) is common to Tahiti and 

 Van Diemen's Land. Mr. Cuming, before our voyage, procured 

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

 several species not yet specifically examined, of Trochus, Turbo, 

 Monodonta, and Nassa. He has been kind enough to give me 

 the following interesting results : of the ninety shells no less 

 than forty -seven are unknown elsewhere — a wonderful fact, 

 considering how widely distributed sea-shells generally are. Of 

 the forty-three shells found in other parts of the world, twenty- 

 five inhabit the western coast of America, and of these eight 

 are distinguishable as varieties ; the remaining eighteen (including 

 one variety) were found by Mr. Cuming in the Low Archipelago, 

 and some of them also at the Philippines. This fact of shells 



