48 INTRODUCTION. 
As, for reasons which may bo gathered from the pre- 
ceding remarks, the genera and species of the pneumo- 
branchiate mollusks proposed by M. Rafmesque, are 
considered to be destitute of authority, and entirely 
unworthy of notice, no mention Tvill be made of them 
in the text. But, to shield the author from a charge, 
from any quarter, of having designedly suppressed them, 
a brief account of all of them known to him, is here 
added. In a memoir published in the Journal de Phy- 
sique, Paris, June, 1819, M. Rafmesque proposed no 
less than seventy new genera of North American ani- 
mals, among which eight were formed out of the genus 
Helix. These are founded, upon only slight variations 
of the aperture of the shell, and so similar are some of 
them to each other, that where he saw reasons to create 
generic distinctions, others, at the present day, can see 
only such differences as belong to varieties of species. 
The genera proposed by him at that time, were the 
following : — 
Odotropis. " Lip reflected, umbilicus covered, tooth upon 
columella. 
it 13 a positive fact, that in knowledge I have been a Botanist, Naturalist, 
Geologist, Geographer, Historian, Poet, Philosopher, Philologist, Economist, 
Philanthropist. — By profession a Traveller, Merchant, Manufacturer, Col- 
lector, Improver, Professor, Teacher, Lawyer, Draftsman, Arclutect, En- 
gineer, Palmist, Author, Editor, Bookseller, Librarian, Secretary, . . . and 
I hardly know myself what I may not become as yet ; since whenever I 
apply myself to anything which Hike, I never fail to succeed if depending 
on me alone, unless impeded and prevented by lack of means, or the hos- 
tility of the foes of mankind." 
