NELSON AND TAYLOR : ON YORKSHIRE MOLLUSCA. 1 9 



7. Went Vale— River Don, at Doncaster, R.D.M. ; abundant and fine 



in Nostel Lakes, one obtained by Mr. H. Richardson being 

 44 X 27 X 20 mill. 



8. Deatne — Wakefield and Barnsley Canal at Royston ! and below Barugh 



Locks, Barnsley, A.P.T. ! 



9. Don — There are specimens in the Museum at Sheffield from the canal 



near that town, W.D.R. ! 



12. Lower Calder — Very common in canal at Wintersett, but not large ; the 



largest specimens were under one inch in length, scarcely eroded, 

 thin, and beautifully marked, W. E. Brown. It is worthy of remark 

 that Mr. Ashford, writing in 1854, of specimens from the same 

 locality, says, ' attached in masses to stone as usual, but almost 

 every specimen corroded by the water.' Common in Cold Hiendley 

 Reservoir ! New Miller Dam ! Wakefield and Barnsley Canal at 

 Agbrigg ! 



13. Airedale — Leeds and Liverpool Canal at Armley ! Kirkstall ! Nevvlay ! 



Rodley ! Calverley ! Apperley ! Bingley ! and Keighley ! 



Class GASTROPODA. 



Order PECTINIBRANCHIATA. 



Family NERITID^. 



Genus NERITINA Lamarck. 



Unlike other of our genera, Neritina is hardly founa in 



North America, but has its head-quarters in the islands of the 



Pacific Ocean, where numerous species are found. 



We have but one species in England, which is also diffused 

 throughout Europe and the adjacent portions of Africa and 

 Asia. Our species is not a typical Neritina, but belongs to 

 the subgenus Vitta of Klein, according to Adams, Chenu, and 

 other systematists. 



Neritina fluviatilis (L ). 



Locally abundant. 



This species is variable both in form and ornamentation, 

 ranging in coloration from an uniform yellow (var. cerina Col- 



