212 Mr. Brooke on Conchology regarded as a Science. 



yet a few lines further on, he has the expression, " The shells which 

 " form this genus," &c. Is, it may be asked, Melanopsis an animal 

 or a shell, or both ? and is not the name derived from the shell ? 



Under Catophragmus Mr, Sowerby alludes to " correct first princi- 

 " pies" — he, however, slates that these " are only to be obtained by 

 " the study of the MoUusca which form and inhabit shells," " yet (he 

 " says) the shells themselves may in most cases be regarded as indicating 

 " many of the more important facts in connection with the history of 

 " their animal inhabitants, and may consequently be generally consi- 

 " dered as sufficient to demonstrate characters strong enough for the 

 " establishment of genera." But genera of what ? animals or shells ? 

 If of annuals, they do not properly belong to Mr. Sowerby's work on 

 shells, and if of shells, the passage means no more than that genera of 

 shells may be established upon the characters of shells alone. The re- 

 mark that genera of animals form no part of Mr. Sowerby's work is 

 strongly enforced by himself, under the genus Dentalium, where he says, 

 " whatever may be the nature of their animals, we are engaged to give 

 " an account of shells alone.'''' And the genus Jlnostoma affords an in- 

 stance of the establishment of a new genus from the form of the shell 

 alone, where the animal is supposed to resemble that of Helix. The 

 consequence of thinking about animals while writing about shells, is the 

 occasional production of observations which could not otherwise have 

 been made ; as, for example, the quotation from Lamarck, under the 

 genus Cassis, " that the shells live in the sea at a distance from the 

 " shores, and upon sandy bottoms, where they bury themselves in the 

 " sand." And under Achatina Mr. Sowerby speaks of shells of differ- 

 ent characters and habits. 



It is not obvious what is intended to be implied by the phrase habits 

 of shells, if it be not their colours and their epidermis, (the latter of 

 which, it may be observed, is frequently a very loose habit,) unless in- 

 deed the practice of burying themselves be termed a habit, to which we 

 are perhaps indebted for the preservation of the numerous fossil speci- 

 mens that now exist, and which may be conceived to have formerly prac- 

 tised self-interment more or less profoundly, in all the then subjacent 

 beds of seas and lakes. 



A similar want of precision in the use of terms connected with this 



