398 7. 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 :— 
aboriginal creations, found no where else; there is even a differ- 
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 600 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 flora 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, procuredg 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. 
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 (ircluding 
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 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 concholog- 
ical provinces have each sent several colonists. ‘The American 
province has also sent here representative species, for there 1s 4 
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 
Se pena 
__* Prof. Edw. Forbes alluding to the fauna and flora of the Galapagos Islands, ob- 
serves, “ We have distinct systems of creatures rela those of the nearest land 
 paarongeae or affinity, and not by identity.”—Mem. Geol. Soc. of Gt. Britain, 
P- 
