MELVILL — MARINE MOLLUSCA. 83 



Family NeritidaB. 



41. 'Nerita albicilla, L. 

 Loc. Coetivy I. 



Chagos Archipelago. 

 Most of the Neritce here mentioned are of universal occurrence through the eastern 

 tropical area and extending into warm temperate regions, albicilla, pUcata, and polita, 

 perhaps, being the most frequent. 



42. Nerita histrio, L. 

 Loc. Chagos Archipelago. 



43. Nerita plexa, Chem. 

 Loc. Chagos Archipelago. 



Seychelles : Praslin I. 

 Coetivy I. 



44. Nerita plicata, L. 

 Loe. Chagos Archipelago. 



Seychelles : Praslin I. 



45. Nerita polita, L. 

 Loc. Coetivy I. 



Chagos Archipelago. 

 Erom the first-named locality (Coetivy) come a series of very finely-coloured varieties, 

 ranging from pure white to deep black, with every intermediate of hue, crimson, orange, 

 yellow, pink, and white striped, pink with green spiral band, and likewise spotted forms. 



46. Neritina ualanensis. Lesson. 



Neritina ualanensis, Lesson, Voyage de la ' Coquille,' Zool. p. 379. 

 Neritina mertoniana, Recluz, Proc. Zool. Soc. Lond. ISiS, p. 71. 



Loc. Amirantes : S. Joseph I. 



Very widely distributed throughout the whole Eastern tropics ; and, as Prof. E. von 

 Martens well observes (Journ. Linn. Soc, Zool. xxi. (1889) p. 172), it " resembles 

 somewhat N. virginea, L., from the West Indies, but is essentially distinct in the 

 operculum ; extremely variable in colours, usually ornamented with very fine dark lines 

 on a shining greenish ground." 



47. Neritina rangiana, Recluz. 

 Loc. Chagos Archipelago : Salomon I. 



The Eastern exponent of the well-known West-Indian N. viridis, L. 



11* 



