550 



impressions, which in W. Suffreni are broad, are still more so in 

 this species, leaving a very narrow slip of the inner surface of the 

 shell between them. 



9. Navicella lineata (pi. cxviii. f. 21, 22, 23, 24, 25), 

 Lamarck, Anim. sans vert. Septaria Navicula, Ferussac. 



N. testa elongata, epidermide tenuissima, nigro vel rubro longi- 

 tudinaliter fasciata seu reticulata, seu seriatim maculata ; apice 

 angusto, plerumque roseo, marginem vix superante ; septo latius- 

 culo, trigono, margine arcuato ; operculo elongate, ad terminum 

 acute dentato, emarginato. 



The most lengthened and narrow of all the species, with the 

 apex narrow and protruding very slightly beyond the margin; 

 the septum trigonal, and the operculum elongated. The colours, 

 either red or black, are for the most part arranged in longitudinal 

 lines or bands, but, in some varieties, reticulated. 



Indian rivers ; Lamarck. Yar. f. 25, Botanic Gardens, Cal- 

 cutta. Many varieties, from the Islands of Luzon and Mindinao, 

 Philippines ; Cuming. 



10. Navicella tessellata (pi. cxviii. f. 26, 27, 28. pi. cxviii. 

 bis. f. 48, 49), Lam., Anim. s. vert. N. Entrecastauxii, (f. 34.) 

 Recluz, Rev. Zool. 1841, p. 380. 



N. testa oblonga, epidermide tenuissima, nigro vel rubro qua- 

 dratim tessellata vel reticulata; apice vix marginem tegente; septo 

 latiusculo, subconvexo, margine arcuato ; operculo breviusculo. 



Rather broader and more square than N. lineata, with the apex 

 scarcely touching the edge, and not so much narrowed. The 

 difference in the marking can scarcely be regarded as constant, 

 although in this species there is a greater tendency to a tessel- 

 lated form. 



Ceylon (var. f. 25); Mr. Middleton. On stones in rivers; Islands 

 of Luzon and Mindinao, Philippines ; Cuming. 



11. Navicella cyEituLESCENs (pi. cxviii. f. 29, pi. cxviii. bis. 

 f. 36, 37, 38), Recluz, MS. 



N. testa breviuscula, subdepressa, subquadrata, cserulea, maculis 

 nigris angulatis picta ; margine apicem superante; septo angus- 

 tissimo, arcuato. 



Resembling N. tessellata, but with the septum extremely narrow 

 and arched ; the shell is also broader in proportion to its length. 



Ganges River, Bengal; collected on stones by Mr. Westerman. 



