NERITIDiE. 83 



1.1. Neritin a fluviatilis. River Neritine. (t. 8. f. 124.) 



Shell convex, dilated, tessellate, with variously 



coloured spots ; spire short, lateral. 

 Neritina fluviatilis. Lamarck, vi. ii. p. 188. ; Flem. 



B.A.321.; Turton, Man. ed. 1. 138. 

 Nerita fluviatilis. Linn. S. Nat. 1253. ; Muller, ii. 



194. ; Drap. p. 31. t 1. f. 1—14. ; Brard, p. 194. 



t. 7. f. 9, 10. 12. ; Mont. p. 470. ; Turt. Diet. 127. 

 Theodoxus Lutetianus. De Montfort, ii. p. 351. 

 Neritina fontinalis. Brard, Hist. C. 196. t. 7. f. 11. 



13. ; Pet. Gaz. t. 91. f. 3. ; List. Conch, ii. 1. 38. ; 



Sicamm. B. N. 80. t. 10. f. 2. 

 Neritina Dalmatica. Sow. C. Illus. f. 57. 



In slow rivers, adhering to stones. 



Animal white ; head and back of the neck blackish ; 

 hinder part of the foot sometimes black spotted ; ten- 

 tacle long, white, with blackish line. 



Shell about three eighths of an inch long, and two 

 broad, convex above and flat underneath, obscurely 

 striate transversely, of a greenish or whitish colour, 

 variously checquered with spots or bands of white, 

 brown, purple, or pink ; spire consisting of three vo- 

 lutions, the first very large, oblong, and oblique, the 

 others small and lateral ; aperture horizontal, semiel- 

 liptic, with the margin sharp and entire ; pillar white, 

 transverse, sloping down to a sharp edge, and quite 

 entire ; operculum semilunar, yellowish, with an orange 

 border, and underneath is a strong raised grooved 

 spire at one end. 



The shells are often covered with calcareous incrust- 

 ations, deposited by the water, which make them 

 E 6 



