152 LIMN7RAD.E. 



P. NAUTiLEus, Linnaeus. 



Very small, usually with membranaceous ridges ; periphery 

 angulated ; mouth entire, rounded-oval. 



Plate CXXVI. fig. 6, 7. 



Hciii' Nauiileu!', Linn. Syst. Nat. cd. 12, p. 1241. — Mont. Test. Brit. p. 464, 



pi. 25, f. 5. 

 Plimorhis imbrkatus, MIller, Hist. Verm. pt. 2, p. I(i5. — Jeffreys, Trans. 

 Linn. Soc. vol. xvi. p. 38fi. — Turt. Manual L. and F. 

 W. Shells, p. Ill, pi. 8, f. 94.— Gray, Manual L. and 

 F. \V. Shells, p. 261, pi. 8, f. 94. — Brown, Illust, 

 Conch. G. B. p. 31, pi. 1 4, f. 46, 47, and pi. 18, f. 1 0.— 

 Drap. Moll. Ter. et Fluv. France, p. 44, pi. 1, f. 49, 50, 

 51. — Brard, Coq, Paris, p. 163, pi. 6, f. 10, 11.— 

 Lam. Anim. s. Vert. (ed. Desh.) vol. viii. p. 389. — 

 C. Pfeif. Deutsch. Land nnd Slissw. Moll. pt. 1, p. 80. 

 pi. 4, f. 15, 16. — Nils. Moll. Suec. Ter. et Fluv. p. 76. 

 — Hartm. in Sturm. Deutsch. Fauna, pt. 7, pi. 14. — 

 KicKX, Moll. Brakmt. p. 67. — Mermet, Moll. Pyrtn. 

 p. 59. 

 „ cristatiis, DraI". Moll. Ter. et Fluv. France, p. 44, pi. 2, f. 1, 2, 3. — 

 Hartm. in Sturm. Deutsch. Fauna, pt. 7, pi. 13. — IVIermet, 

 Moll. Pyren. p. 60. 

 Ttivho Nautilcus, MATONand Rack. Trans. Linn. Soc. vol. viii. p. 169, pi. 5, f. 4. 

 — Rack. Dorset Catalog, p. 50, pi. 19, f. 16. — Turt. Conch. 

 Diction, p. 227, f. 78.— Wood, Index Testae, p. 32, f. 162.— 

 DiLLW. Recent Shells, vol. ii. p. 882. 

 Planorbis Nautilus, Fleming, Brit. Anim. p. 278. 



„ Nautileus, Dupuv, Moll. Gers, p. 51. — Stein, Schnecken Berlins, pi. 2, 

 f. 24.— Walker, Testae. Minut. Rariora, f. 20, 21. 



Shell very small, much depressed, very fragile, not lus- 

 trous, of a slightly olivaceous horn-colour, often invested 

 with a black incrustation, adorned for the most part (for 

 occasionally they are obsolete) with distant subimbricated 

 longitudinal membranaceous rings, or ridges, which are 

 iisually more marked on the lower disk, and serrate the 

 periphery by their projection as vaulted scales. Whorls 

 three, very rapidly developed, profoundly divided, more 

 convex on the lower disk, v^hich is umbilicately hollowed, 



