NERITINA-NAVICELLA, 77 



Subgenus Dostia, Gray, 1840. 



N. CREPiDULARiA, Lam. PI. 23, figs. 95-99. 



Very convex, lightly striulate, sometimes unicolored, varying from 

 light yellowish, or olivaceous to blackish, but usually reticulated, 

 checkered or spotted with a light color on a dark ground or dark on 

 a light ground, frequently the darker tint is violaceous, and some- 

 times it is reddish ; aperture bluish, bluish grey, yellowish grey etc., 

 peristome continuous, columellar area slightly rugose, margin a 

 little arcuate and dentate in the middle. Diam. 15-25 mill. 



Indian Ocean, India to Malay Archip., China, Philippines, Neiv 

 Caledonia. 



The form is pretty constant, but the coloring exhibits considerable 

 variation, within rather narrow limits, however; not sufficient to 

 excuse the immense synonymy. It is N. violdcea, Gmel. in part, 

 N. jmrpurea and N. gracilenta, Budgin, N. concentriea, N.p)lumata and 

 N. mitrida, Menke, iV. intermedia, Desh., N. eornuco2nai, and N. de- 

 jjressa, Benson, N. melanostoma, Troschel, N. Indicce and N. TouT' 

 annensis, Souleyet, N. Siquijorensis, N. exaltata. and iV^. pileolus, 

 Recluz, N. Schlcejlii and N. compressa, Mousson, and N. Montrouzieri, 

 Ga8sies. 



N. LiFUENSis, Angas. Unfigured. Viii Is. 



N. LACUSTRis, Jan. Unfigured. Brazil. 



Unassigned species described as Neritinye. 



N. PYGMiEA, C. B. Adams. Jamaica. 



N. PusiLLA, C. B. Ad. =Teinostoma. 



N. neglecta, Pease. Sandwich Islands. 



N. MINIMA, Recluz. Nukahiva. 



N. Hessei, Bottger. Moidh of River Congo, W. Africa. 



Genus NAVICELLA, Lam., 1809. 

 Section Cimber, Montfort, 1810. 



The shells of the Navicellee are modified in form and convexity 

 according to the nature of the surface to which they adhere ; thus 

 the form called N. lineata, is a N. tessellata, higher and laterally 

 compressed from inhabiting the stems of sea- weed, whilst the typical 

 N. tessellata is from surfaces giving the shell a chance to spread ; so 



