Biblioyraphical Notice. 127 



Freshwater Mollusks of tlie British Isles,' pretend to the complete- 

 ness aiul originality of JclTreys's work. 



The loiij; interval since the ptiblication of that book, and the 

 numerous ehan<;es which have been made in classilication and in 

 nonu'uclature, are an answer to the (jucstion whether another 

 treatise on this subject was wanted. 



Jud-^inp from the part of Mr. Taylor's work before us, it would 

 appear that the subject will be treated in a far more exhaustive 

 manner than has ever been attempted previously. We know from 

 the 'Journal of Conchology ' that the author was accumulating 

 material at least ten years ago, and therefore, as ample time in the 

 preparation of a work of this kind is so indispensable to ensure 

 thoroughness, we may anticipate a very full and detailed account of 

 the subject. 



From a prospectus accompanying this part, it appears that the 

 work is to be completed in two volumes. The first will be devoted 

 to a general treatment of the subject, the ditlerent forms and cha- 

 racters of the shell, the mor[)hol(>gy of the animal, and descriptions 

 of the structure and functions of the various organs ; geological and 

 geograj)hical distribution, habit-s, parasites, enemies, uses, develop- 

 ment, &c. The second volume will contain an account of the species 

 individually. 



Part I. consists of 6-1 pages of text, illustrated with 13G process 

 blocks and one coloured plate as a frontis])iece. 



It commences with a definition of conchology and a few remarks 

 upon the limitation of tlie subkingdom ^lollusca. The following 

 eight pages are devoted to classification, the scheme adopted being 

 that elaborated by Professor Kay Lankester in the * Encyclopaedia 

 Britannica.' 



Nomenclature is then discussed, and instruction given in the 

 formation of generic and specific names. In talking of synonymy 

 our author informs us that ior Limncea perer/ra " over three hundred 

 names have been catalogued, all specifically synonymous I " Wc 

 sincerely trust that he will not burden his readers with a complete 

 list of them. 



Thirty-six pages are occupied with various points iu connexion 

 with the shell. Its structure and chemical composition, the nume- 

 rous forms it assumes, and the various kinds of surface-ornamenta- 

 tion (sculpture) which adorn it are all exjdained, the descri])tions 

 being assisted with explanatory figures. The names associated with 

 the various parts of shells are expounded, and the manner in which 

 they are measured is also indicated. The rest of the part is occu- 

 ]iied with some remarks upon species and varieties, and the various 

 causes which tend to their production. 



The matter contained in this part, although having sjiecial 

 reference to the land and freshwater Mollusca, has a general bearing 

 on tlie science of conchology as a whole. It contains very few new 

 observations, but constitutes a clear and instructive rcsvinc of the 

 subjects treated of. 



There are many students and collectors of British land and fresh- 



