Mr. Brooke on Conchology regarded as a Science. 211 



that the species Cydostoma elegans is the same as is described in Monta- 

 gu's "Testacea Britannica," as Turbo elegans. He accordingly turns to 

 Montagu's work, and finds that Turbo is a shell, and that the animal 

 inhabitant is stated to be a Limax. He discovers also that the name Cy- 

 clostoma was given to the shell in question from the circular form of its 

 aperture, a character to which Dr. Fleming does not allude ; but this dis- 

 covery brings with it a new embarrassment, for the second species of Dr. 

 Fleming's Cydostoma is described as having an ovate mouth. 



He turns over the remaining pages of Dr. Fleming's descriptive cha- 

 racters without feeling his difficulties much removed : on the contrary, 

 they are frequently increased by the numerous typographical errors with 

 which the volume abounds, (and which will doubtless be corrected in an- 

 other edition,) as well as by the occasional inattention of the learned 

 author — as where he describes the shells belonging to the animals of the 

 first division of the Siphonida, page 408, as having the beaks obsolete ; 

 the first genus of that division, Mytilus, as having the beaks acute ; and 

 the first species of Mytilus as having the beaks blunt. 



The enquiries of the student not having been satisfied elsewhere, he 

 now refers himself to Mr. Sowerby's "Genera of Recent and Fossil Shells," 

 and here he is again doomed to disappointment ; for notwithstanding the 

 practice of accurate observation which is evinced by the descriptions con- 

 tained in Mr. Sowerby's work, and the occasional influence of his better 

 judgment in shaking ofif the trammels with which his subject has been 

 surrounded, he allows himself too frequently to be influenced by the 

 reigning notion, that in his descriptions of shells he must always appear 

 to think and talk about molluscous animals. 



Under the genus Pullasira, Mr. Sowerby implies, that it is the habits 

 of the animals which ought to be the foundation of the genera of shells. 

 If the habits of the animals be not here taken to mean the shells them- 

 selves, it is evident that no genus of fossil shells can ever be established. 



The title of Mr. Sowerby's work is the " Genera of Recent and Fossil 

 Shells,^'' yet under the genus Magilus he speaks " of giving the genera of 

 " all animals whose habitations have usually been called shells" and 

 under this view he will doubtless include the Hermit Crab. 



Under Melanopsis, Mr. Sowerby quotes from M. de Ferussac, " The 

 " genus Melanopsis is one of the most interesting of molluscous animals' ' ; 



o2 



