390 7. Bland on the Geographical Distribution of Mollusca. 
in his paper on “ The results of an examination of the shells of 
Massachusetts, and their Geographical distribution,” read in 
February, 1841, before the Boston Society of Natural History, 
(published in the third volume of the Society’s Journal, ) and in 
his subsequent works.—Professor Adams takes up the subject 
in his “ Second Annual Report on the Geology of the State of 
Vermont,” dated October, 1846, as well as in his later publi- 
cations. 
The latter author has had the particular advantage of work-: 
ing somewhat extensively in the wide field of nature. His 
“ Caribbean,” and “Panama.” An important step towards this 
object is gained, as regards the latter, by the publication men- 
tioned at the commencement of this article, and the author is 
now employed, we understand, in the preparation of a more com- 
plete work, illustrative of the former. 
We desire to shew the interest and value which are attached 
to the. question of the geographical distribution of shells,—not 
only generally, as part of the animal kingdom, but in its especia 
reference to geology. Although it may appear that much has 
een discovered and written on the subject, it will be equally 
apparent that very much remains to be worked out. _ ; 
We propose also to refer to the causes of error on the subject, 
and to the question of the origin of species, which is intimately 
connected with the fact, that different regions of the globe, both 
of land and water, are inhabited by distinct groups of animals 
and plants. : : 
It being our wish to excite increased attention to these subjects, 
we have preferred quoting largely from works of authority, to offer- 
ing a summary of views and opinions in language of our own 
Buffon first pointed out the want of specific identity between 
the land quadrupeds of America, and those of the old w Id. 
Humboldt demonstrated that zones of elevation on mountains 
correspond to parallels of latitude, the higher with the more 
northern or southern, as the case might be. But for a lucid and 
succinct account of the progress and extent of our knowledge of 
the geographical distribution of species, both of plants and an 
‘mals, we must refer to the admirable chapters relating to It, 2 
- Sir Charles Lyell’s Principles of Geology. at 
ie 
