I83S-] DISTRIBUTION OF SHELLS. 285 



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

 and Nassa. He has been kind enough to give me the following in- 

 teresting results: of the ninety shells, no less than forty-seven are 

 unknown elsewhere a wonderful fact, considering how widely dis- 

 tributed 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 from islands in the central parts of the Pacific 

 occurring here, deserves notice, for not one single sea-shell is known 

 to be common to the islands of that ocean and to the west coast of 

 America. The space of open sea running north and south off the west 

 coast, separates two quite distinct conchological provinces ; but at 

 the Galapagos Archipelago we have a halting-place, where many new 

 forms have been created, and whither these two great conchological 

 provinces have each sent several colonists. The American province 

 has also sent here representative species ; for there is a Galapageian 

 species of Monoceros, a genus only found on the west coast of 

 America ; and there are Galapageian species of Fissurella and Can- 

 cellaria, genera common on the west coast, but not found (as I am 

 informed by Mr. Cuming) in the central islands of the Pacific. On 

 the other hand, there are Galapageian species of Oniscia and Stylifer, 

 genera common to the West Indies, and to the Chinese and Indian 

 seas, but not found either on the west coast of America or in the 

 central Pacific. I may here add, that after the comparison by Messrs. 

 Cuming and Hinds of about two thousand shells from the eastern 

 and western coasts of America, only one single shell was found in 

 common, namely, the Purpura patula, which inhabits the West Indies, 

 the coast of Panama, and the Galapagos. We have, therefore, in this 

 quarter of the world, three great conchological sea-provinces, quite 

 distinct, though surprisingly near each other, being separated by long 

 north and south spaces either of land or of open sea. 



I took great paias in collecting the insects, but, excepting Tierra 

 del Fuego, I never saw in this respect so poor a country. Even in 

 the upper and damp region I procured very few, excepting some 

 minute Diptera and Hymenoptera, mostly of common mundane forms. 

 As before remarked, the insects, for a tropic?! region, are of very small 

 size and dull colours. Of beetles I collected twenty-five species (ex- 

 cluding a Dermestes and Corynetes imported, wherever a ship touches) ; 

 of these, two belong to the Harpalidae, two to the Hydrophilidse, nine 

 to three families of the Heteromera, and the remaining twelve to as 

 many different families. This circumstance of insects (and I may add 

 plants), where few in number, belonging to many different families, is, 

 I believe, very general. Mr. Waterhouse, who has published * an 

 account of the insects of this archipelago, and to whom I am indebted 

 for the above details, informs me that there are several new genera ; 

 and that of the genera not new, one or two are American, and the rest 

 * dn. and Mag. of Natural History, vol. xvi., p. 19. 



