398 T. Bland on the Geographical Distribution of Mollusca, 



Darwin, in his admirable ^^ Journal of Researches,''^ comments 

 on the distribution of shells in the Galapagos Archipelago, and 

 no more instructive instance of the value of the study can be 

 afforded. The author observes : — 



" The natural history of these islands is eminently curious, and 

 well deserves attention. Most of the organic productions are 

 aboriginal creations, found no where else ; there is even a difler- 

 ence between the inhabitants of the different islands; yet all 

 shew a marked relationship with those of America, though sepa- 

 rated from that continent by an open space of ocean between 500 

 and 000 miles in width. The archipelago is a little world within 

 itself, or, rather, a satellite attached to America, whence it has 

 derived a few stray colonists, and has received the general char- 

 acter of its indigenous productions." — p. 145.* 



Darwin, after the above generalization, enters into particulars 

 of the peculiar fauna and fiora of these islands, from which we 

 make the following extract: — 



" Of land shells I collected sixteen kinds, (and two marked va- 

 rieties,) of which, with the exception of the Helix found at Ta- 

 hiti, all are peculiar to this archipelago: a single freshwater shell 

 {Paludina) is common to Tahiti and Van Diemens 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, &c. 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 

 from islands in the central parts of the Pacific occurring here de- 

 serves 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 runnmg 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 concholog- 

 ical 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 found only on the west 

 coast of America ; and there are Galapageian species of Fissu- 

 rella and Cancellaria, genera common on the west coast, but not 



* Prof. Edw. Forbes alluding to the fauna and fiora of the Galapagos Islands, ob- 

 serves, "We have distinct systems of creatures related to those of the nearest land 

 by 7-epresentation, or affinity, and not by identity." — Mem. GeoL Soc. of Gt. Britain, 

 vol. i, p. 402, Note. 



