56 Bibliographical Notices. 



process, the fibres of wood or grains of sandstone may easily be de- 

 tached or disintegrated, time and patience being allowed for the 

 operation. "When it is considered that the hole made by an adult 

 Pholas or Saxicava is only a few inches deep, and that an aged Pa- 

 tella scarcely jienetrates a quarter of an inch into a limestone-rock, 

 there can scarcely be a question that these moUusks have abundance 

 of time to effect their purpose. It is said that even the hardest 

 marble is not proof against the softest impressions, and that the big 

 toe of St. Peter's statue in the Vatican has been nearly worn away 

 by the lips of fair devotees. The osculatory process is not unlike 

 that of suction." 



In the second portion of the work a uniform plan has been adopted. 

 The animal is first described, then the shell and its varieties ; and 

 these descriptions are followed by a commentary upon the range, 

 habits, and nomenclature of the species in question. The different 

 parts of the animal and shell are also invariably characterized in the 

 same order — a methodical plan which has great advantages, and 

 which ought always to be adopted in descriptive works on natural 

 history. 



Mr. Jeffreys' s computation of the number of our inland Mollusca 

 is almost the same as that of Messrs. Forbes and Hanley, the former 

 enumerating 121, and the latter 122 species. There is, however, 

 considerable diversity as to the means by which these numbers are 

 arrived at. The author of * British Conchology ' has struck out of 

 the list the following Mollusca, as being either merely varietal forms 

 or erroneously recorded species : — Pisidium obtusale, Pfeiffer ; Pi- 

 sidium cinereum^ Alder ; Pisidium Henslowianum, Sheppard ; Arion 

 JlavuSi Miiller ; Limax brunneus, Draparnaud ; Limax tenellus, 

 Miiller ; Helix aperta. Born ; and Limnceus Burnettiy Alder : and, 

 on the other hand, he has given admission to the following : — 

 Sphcerium ovale, Ferussac ; Pisidium roseum, Scholtz, separated 

 from Pisidium pulchellum, Jenyns ; Anodonta anatina, Linnaeus, 

 separated from Anodonta cygnea, Linnaeus ; Succinea elegans, Risso, 

 separated from Succinea putris, Linnaeus ; Helix concinna, Jeffreys, 

 separated from Helix hispida, Linnaeus ; Vertigo Moulinsianoy 

 Dupuy, now first recorded as a British species, having been taken by 

 Mr. Jeffreys in the west of Ireland ; and Vertigo alpestris, Alder, 

 separated from Vertigo pygmcea, Draparnaud. We are unable to 

 acquiesce in many of these changes, though in the majority of in- 

 stances the decision which the author has arrived at appears to be 

 fully justified. But Mr. Jeffreys is not content with species ; in 

 this work he introduces to British conchologists no less than one 

 hundred and eighty-four named varieties. It has always appeared 

 to us that the use of names as applied to varieties is most undesirable, 

 and therefore should only be adopted in cases where the forms are 

 so strongly marked as either to have already been characterized as 

 species by previous describers, or at least to be possessed of features 

 so greatly at variance with the type that the description of the nor- 

 mal form would of itself be insufficient for their identification. 

 Names, for instance, have been given, we think, rightly by Mr. Dar- 



