1835.] DISTRIBUTION OF SHELLS. 385 



remarkable, because it is the only existing lizard which 

 Jives 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 Amhlyrhynchus 

 — 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 re- 

 places the herbivorus 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. Gumming, before our voyage, procured here 

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

 several species not yet specifically examined, of Trochus, 

 TurbOf 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 t/ 

 .1 wonderful fact, considering how widely distributed 

 -i-shells generally are. Of the forty-three shells found 

 in other parts of the world, twenty -five inhabit th* 

 western coast of America, and of these eight are dis 

 tinguishable as varieties : the remaining eighteen 

 (including one variety) were found by Mr. Gumming 

 in the Low archipelago, and some of them also at tin- 

 Philippines. The tact of shells from islands in the central 

 • trfs (^'^ til'- l';ir ific occurring here, deserves, notico 



