British species of the genus Lagcna. 11 



followed will not suit the views of many of my conchological 

 friends, who would have preferred my multiplying the number of 

 species to a far greater degree than I could approve. I have 

 however endeavoured to compromise the matter with them by 

 giving names to what I consider to be merely varieties, but which 

 some would regard as good species. Those who prefer the latter 

 view can act upon it if they choose, by adopting these names as 

 specific ones. This capacity for variation is probably a charac- 

 teristic of very many of the lowest forms of animal and vegetable 

 organizations, and is a source from which more or less of diffi- 

 culty will always arise in attempting to classify objects so small 

 in their dimensions and so obscure in their nature. In the pre- 

 sent case it would scarcely be a difficult task to exhibit every in- 

 termediate form between Lagena Icevis. var. Amphora to L. striata 

 and L. substriata, rendering it possible that they may be all va- 

 rieties of one species. 



The LagencB are usually found in dried sea-sand, free and de- 

 tached, though Prof. MacGillivray observed Lagena iavis to be 

 adherent to Fuci and the byssus of a Modiola ; and amongst the 

 branches of an Antennularia sent to me from Falmouth by Mr. 

 Jeffreys were numbers of the Entosolenia marginata along with 

 Rosalina glohularis and Polystomella crispa. 



In dividing the objects comprehended by Dr. Fleming, in De 

 Montfort^s genus Lagenula, into two groups, I have retained for 

 the first of these Walker's term Lagena. Though the latter did 

 not make them into a new genus, separate from Serjjula, yet he 

 distinctly indicated the necessity for a division, pointing out cer- 

 tain well-marked forms, and giving them a distinguishing name. 

 In this he accomplished more than was subsequently effiicted by 

 De Montfort ; hence, in raising them to the rank of a genus, pri- 

 ority gives his name of Lagena the right to a preference before 

 that of Lagenula. The adoption of the latter by English concho- 

 logists was owing to its introduction by Dr. Fleming into his 

 ' British Animals,' where he employed it, I understand, because 

 of its being more euphonious than Lagena, notwithstanding 

 that, as has been already mentioned, he had previously adopted 

 Walker's very expressive term for the genus in the ' Edinb. Ency- 

 clopaedia' (vol. vii. pi. l.p. 68, art. Conch. 1815). A slight im- 

 provement in the sound, or even expressiveness of a name, does 

 not justify its displacing an older one, and hence throughout 

 this memoir I have retained that of Lagena in preference to 

 Lagenula. 



Genus Lagena, Flem. Edin. Enc. 



Serpula (Lagena), Walker. Serpula, Turton. Vermiculum, Mon- 



