318 MOIXUSCA. PECTINIBRANCHIA. Nerita. 

 NERITADiR. 



* Marine. 

 Nerita. 

 Natica. 



•• Fluviafile. 

 Neritina. 



Gen. LVII. NERITA. — Pillar-lip flat, entering the cavity, 

 entire behind. 



270. N. littoralis. — Whorls five, nearly smooth, the outer hp 

 thin on the edge, thickened within. 



Nerita ex fusco-viridescens, List. An. Ang. 164, t. iii. f. 11, 12, 13. Conch, 

 t. Dcvii. f. 39-44 — N. litt. Linn. Syst. 1253. Mont. Test. Brit. 467. 

 — Common on sea rocks, covered witli the tide. 

 Length and breadth about three-quarters of an inch. Shell thick and 

 strong, variously coloured ; whorls increase rapidly, spire short, depressed, 

 the separating line small ; aperture semicircular, but the pillar is more round- 

 ed anteally, where it joins the outer lip, than is usual m the genus; hence 

 Lamarck has placed the shell in the genus Turbo ( T. retusus., Hist. "Vert. vii. 

 48.) ; a subperforation appears on the pillar. This shell is subject to consi- 

 derable variation in the shape, arising from the spire being more or less pro- 

 duced ; the body-whorl round or compressed, and the outer lip retrally join- 

 ing the upper or middle part of the whorL 



271. N. Vh'ginea. — Smooth, polished; pillar-lip toothed. 



Nerita, List. Conch, t. Dcvi. f. 35. Turton's Conch. Diet. 127 — West 

 coast of Ireland. 

 Breadth of those found by Dr Turton hardly the eighth of an inch, pale, 

 ferruginous, with black zigzag lines running in various directions ; whorls lit- 

 tle raised, a black line round the junctions. 



EXTINCT SPECIES. 



l.'N.lcevigafa — Pointed, smooth ; spire conical, with straight sides ; base 

 convex Sower. Min. Conch, t. ccxvii. f. i. — Inferior Oolite. 



2. N. sinuosa Obtuse, uneven ; spire short, with convex whorls ; aperture 



with a rounded sinus near the base, and an angular sinus near the middle — 

 Sower. Min. Conch, ccxvii. f. 2 — Portland Oolite at ChUmarsh. 



3. N. globosa — Subglobose, transversely sulcated ; spire apparent ; one tooth 

 upon the inner lip ; outer lip plain within — Sower. Min. Conch, t. ccccxxiv. 

 f. 1. — London Clay. 



4. N. aperta Subhemispherical, smooth ; spire visible, depressed ; aper- 

 ture orbicular, expanded ; inner lip obscurely crenated, bearing one large 

 tooth Sower. Min. Conch, t. ccccxxiv. f. 2, 3, 4. — London Clay. 



5. N. minnta. — Hemispherical, smooth ; spire indistinct, aperture oval : 



pillar-lip not toothed Sourr. Min. Conch. I. cccdxiii. f. 3, 4. Oolite at An- 



clifF. 



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