XU INIRODUCTIOIT. 



meister * in 1844 to a Coleopterous insect, and it is here replaced by 

 Bullinelln, a name of new construction. In like manner A. Adams's 

 Volvida of 1850 is altered to Volvulella (also new), on account of Oken f 

 having used it for another genus of iloUusca in 1815. 



This terminates the princijial alterations effected in the generic names 

 entering into the composition of this work, and they form an attempt to 

 bring about a greater accuracy and uniformity in the nomenclature of the 

 subject, so eminently desirable in Conchological science. 



A notable exception to the priority law has been made in the case of 

 the genus Limnwa of Lamarck, 1799, which name, curious to state, was 

 first applied by Poli, in 1795, for the soft parts of an Anodon. As 

 this determination was never followed by any subsequent author, as far 

 as can be ascertained, there is every tangible excuse for retaining the 

 well-known Lamarckian name. 



It now remains for me to acknowledge the help received from various 

 friends who have from time to time yielded their advice and experience. 

 Foremost among these stands my colleague of the Zoological Department, 

 Mr. Edgar Smith, who has taken a great interest in this work, and has 

 aided me on many occasions, not only by allowing me access to the recent 

 shells under his care for purposes of comparison, but for the unreserved 

 opinion which he has at all times freely given me when we have consulted 

 together on difficulties either in defining the limits of a genus or on 

 points connected with the subject of classification. He also concurs 

 with my views respecting the alterations suggested in the generic 

 nomenclature. To my friends Messrs. Geo. F. Harris and H. \V. 

 Burrows I am indebted for some useful suggestions regarding the specific 

 determinations of many of the Gasteropods. The very fine series of Paris 

 Basin Mollusca possessed by the Geological Department has of course 

 been frequently referred to in the determination of the English forms. 

 Sometimes the particular species required has not been in the Museum 

 Collection ; at such times I have had the privilege of borrowing it from 

 Mr. Harris's private cabinet. For this and other services connected 

 with my work, I beg to tender him my thanks. I wish to acknow- 

 ledge also the valuable information given me by Mr, H. Keeping, of the 

 Woodwardian Museum, Cambridge, during his occasional visits to London, 

 on the subject of localities represented in the Edwards Collection. To 

 Mr. Keeping is due the credit of having collected the chief specimens now 

 forming this unique collection, and his knowledge of the subject is amply 

 testified by his having been a joint author with the late Mr. E. B. Tawney 

 in connection with a memoir published in the Quart. Journ. Geol. Soc. 



* Handb. Entom. 1844, vol. 4. pt. 1, p. 171. 

 t Zool. 1815, p. 313. 



