IS,;:..] DISTRIBUTION OF THE SHELLS. 891 



species not yet specifically examined, of Trochus, Turbo, Mono- 

 donta, 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, consider- 

 ing 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 dis- 

 tinguishable 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 concho- 

 logical provinces have each sent several colonists. The Ame- 

 rican 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 Cancellaria, genera common on the west coast, 

 but not found (as I am informed by Mr. Cuming) in the central 

 island.; of the Pacific. On the other hand, there are Galapa- 

 geian 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 2000 shells from the eastern and western coasts of Ame- 

 rica, 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 dis- 

 tinct, though surprisingly near each other, being separated by 

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



I took great pains 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, except- 

 ing some minute Diptera and Hymenoptera, mostly of common 



