474 NOTES ON PROSOBRANCHIATA, 



Group of L. tritonis. 



L. tritonisj Linn. L. ovoideum, Tate. 



L. rubicundum, Perry. L. variegatum, Lamk. 



L. saulice, Reeve. Z. australe, Lamk. 



L. bassi, An gas. 



The following species are not conveniently referable to any of 

 the above groups : — 



L. subdistorlicm, Lamk. L. tumulosum, Tate. 



L. cyphus, Tate. L. protensum, Tate. 



L. clandestinum, Lamk.f L. fraterculum, Dkr. 



Species incertse sedis. 



L. gramdatum, Dunker. L. contabulatum, Anton. 



L. birostoinum, A. Ad. L. tringa, A. Ad. 



L. papillosum, A. Ad. L. nodoliratum, A. Ad. 



L. dorsuosujii, A. Ad. 



This arrangement, which is similar to that adopted by Pilsbry 

 for the species of the various genera of Helices (28), and Simpson 

 for the Naiades (31), has advantages possessed by no previous 

 arrangement of the genus. None of the sectional names are 

 ([uotable, and are, therefore, not additions to an already over- 

 burdened nomenclature. As the}'- consist of essentially similar 

 species a reference to one of these groups should at once convey 

 to the reader a tangible type; they should, on that account, be 

 of service to the specialist and to the general conchologist when 

 describing new forms. A monograph arranged in this way should 

 greatl}'- facilitate identifications. Since I have worked to some 

 extent from figures and descriptions only, some of m}'- groups 

 may contain species which break their uniformity. 



Miscellaneous Notes. 



Wliile at work on this paper I have made miscellaneous notes 

 of interest, and arrived at conclusions at variance with Tryon's 



t Vide post, p. 479. 



