210 Mr. Brooke on Conchology regarded as a Science. 



destitute of shells. And as PAoZas, Solen, Mya, Madra, are some of 

 his genera of shells, he evidently adopts the Linnean principle of esta- 

 blishing a classification and nomenclature of shells distinct from, and in- 

 dependent of, that of the animal inhabitants. 



In 1822 a work was published by the Rev. Dr. Fleming, entided, 

 " The Philosophy of Zoology, or a General View of the Structure, Func- 

 tions, and Classification of Animals.'" And in 1828 the 1st volume 

 appeared of " a History of British Animals," by the same author, exhi- 

 biting a systematical arrangement of their genera and species. 



At page 406 of the first of these works. Dr. Fleming says, " the cha- 

 " racters furnished by the skin and its appendices are extensively em- 

 " ployed in the systematical arrangement of molluscous animals. Nearly 

 " all those characters which distinguish the species, and many of those 

 " on which genera are established, are derived from theybrm of the shell, 

 " the tentacula, or the colour." If this be really so, that the form of 

 the shell may supply both the generic and specific characters of the ani- 

 mal, the study of shells alone becomes even more important than it has 

 been already supposed. It will, however, appear afterwards that the 

 very reverse of this process is recommended in a later work. 



The subject is again adverted to by Dr. Fleming, at page 430 of the 

 same volume, where he says, " enough is known of the animals of Spi~ 

 " rula and Natitihis to furnish some hints for those who are fond of classi- 

 " fying animals from their analogies.''^ A passage which seems to imply 

 dissent on the part of the author from the method of classing these ani- 

 mals from their analogies rather than from their shells ; a dissent, how- 

 ever, from the only principle upon which, it would appear, a correct 

 classification of animals can be established. 



It is from this conflict of first principles, and the practical conse- 

 quences to which it has given rise, that the ambiguity and uncertainty 

 are produced which meet the conchological student at every stage of his 

 enquiry. If, for example, he turns to the division Cochleadee of Dr. 

 Fleming's British Animals, (page 255,) he observes that the first genus is 

 named Cyclostoma, and which hence would appear to be an animal. But 

 he has perhaps seen a shell so named, and he is therefore at a loss to know 

 whether the term Cyclostoma implies an animal or a shell. To satisfy 

 his doubts he turns to the description of this genus, and he there finds 



