Mr. Brooke on Conchology regarded as a Science. 209 
the animal and shell conjointly. This, however, is not to be done by 
describing a shell, and calling it an animal, nor by imperfectly describ- 
ing an animal of which very little may be known, and denoting it by the 
name which hasbeen previously given to the shell that covers it—a name, 
as Monodonta, almost generally derived from some character of the shell 
alone. 
If the animal inhabitants of all known shells were known, a classifi- 
cation of those animals with appropriate generic and specific names, 
according to the method adopted by Poli, would supply what might pro- 
perly be termed “ An Account of Molluscous Animals ;”” but even in 
this case it would be important to the naturalist to have the shells also 
accurately studied, and perhaps separately named and described, in such 
manner as might best exhibit their peculiar relations to the characters 
and habits of their respective animals. And if there should be found 
some inconvenience in having two sets of names and a double classifica- 
tion, this would be more than compensated by the increased perspicuity 
of the method. 
But if it would be useful to possess this double classification where the 
animals are known, it becomes strictly necessary to keep the two systems 
distinct, in order that one of them should embrace the fossil shells. 
The proper study of shells may indeed not unaptly be considered 
analogous to that of the skeletons of the higher classes of animals, and 
may be regarded as the comparative anatomy of the molluscous inhabit- 
ants; and if it were so pursued, those who study shells alone, might, 
without the fear of being regarded as triflers, confess themselves to be 
conchologists, and might thus assert their title to a place in the ranks of 
science, on account of the additions they might, by induction, supply to 
the present scanty knowledge of the shell-bearing animals. 
A few extracts will now be given from some of our latest writers on 
these subjects, to shew the unsettled state of opinion upon even the first 
principles of the method of treating this branch of natural history. 
Montagu, in his *Testacea Britannica,”’ published in 1803, (Introduction, 
page 27,) says, “ The Ascidia is rather a numerous genus’ (of animals,) 
** is found to inhabit Pholas, Solen, some of the Mya, Mactra, and 
* probably part of other bivalve Testacea: many species of the genus 
* Ascidia are Mollusca’ —the term Mollusca is here applied to’ animals 
Vou. V. o 
