MOLLUSCA. 
TxeE Molluscous animals to which our attention is to be 
directed in this article, formed, for a long period, two dis- 
tinct objects of study. The naked species were considered 
as constituting a particular group, to which the term Mot- 
LUSCA was in a great measure restricted ; whilst the shelly 
species attracted a large share of attention, being known as 
objects of study by the term ConcnoLoey. Of late years, 
however, this kind of systematical separation of the naked 
and shelly species has been supported by few advocates, 
whilst those who have urged the propriety of their union 
have not only been numerous, but acknowledged as the 
intelligent and successful investigators of nature. In con- 
sequence of these changes, which have taken place in pub- 
lic opinion by the introduction of more correct notions of 
the principles of classification, we have in ‘this edition of 
our work, resolved on incorporating the articles MoLtuusca 
and ConcHOLOGY, suppressing the latter term as unneces- 
sary. Indeed, in a physiological point of view, there is no 
definite boundary between the naked and the shelly species, 
many of the reputed naked species having shells concealed 
under their integuments, while in many of the shelly species 
the solid plate or shell can only be reached by removing 
B 
