Fig. 



17. N. monilifera, Lamk. — Nerita glaucina, catena, etc. — Near 



water-mark, in sandy places generally, C. Whorls rounded. 



18. N. sordida, Phil. — N.fulva, plumbea, etc. — Scilly, Cape Clear, 



Zetland, etc., 25 to 90 fath., R. 



19. N. pusilla, Say. — N. Grcenlandica,livida, alba.- — Northumberland, 



Yorkshire, N. Eu., 45 fath., E. White ; umbilicus small. 



Recluzia. 



20. R. aperta, Jeffreys. — Natica aperta, Loven ? — Zetland, Rr. 



Velutina. 



21. N. laevigata, Linn. {Helix.) — Bulla, Velutina, etc.— Brit, co. 



generally, 1 to 30 fath., N. Eu., C. 



22. N. flexilis, Mont. [Bulla.) — Coriocella and Sigaretus plieatilis. — < 



N. Scot., 25 fath., Rr. 



Lam ell aria. 



23. L. perspicua, Linn. — Helix, Bulla haliotoidea, Sigareta and Co- 



riocella neritoideus. — Brit. co. generally, but R. ; 1 to 15 fath., 

 Mr. Thin, glassy, more ventricose than L. tentaculata. 



24. L. tentaculata, Mont. — Sig. and Cor. — Falmouth, Swansea, Ar» 



ran, etc. Laminarian, Mr. Upper whorls less full than L. per- 

 spicua, 



Otina. 



25. 0. otis, Turt. (Helix.) — Velutina, Galericulum ovatum. — Wales, 



Devon, Channel Isls., Clare, etc., Mc. Littoral. 



Triohotropis. 



26. T. borealis, Broderip and Sowb. — T. and Murex carinatus, umbili- 



catus, acuminatus, etc. — N. Scotland, W. Ireland, 15 to 80 fath., 

 R. 







