PRELIMINARY REMARKS. 
Ir is now ten years. since the publication of Dr. Gould’s “ In- 
vertebrata of Massachusetts,” the most valuable work on Ameri- 
can Conchology which has yet appeared. This work, from the 
full and judicious descriptions it contains, must always remain 
a standard for the accurate determination of the species of 
which it treats. But the rapid progress which has been made 
in Malacology during the last few years, and the new principles 
which have been introduced into the science, render necessary 
a great change in the arrangement and nomenclature adopted 
in that Report. The work now offered to the public is intend- 
ed to contain all the species which have been detected in New 
England up to the present moment, arranged and named in ac- 
cordance with the present state of our knowledge. To show 
the necessity of such a work at the present time, I may men- 
tion that, of the three hundred and forty-four species here men- 
tioned, only one hundred and thirty-seven are described in Dr. 
