549 



centre. The operculum is rather more oblong, and much more 

 strongly lobed : it is generally of grey colour. The external 

 sui-face is also very slightly striated in direction of the lines of 

 growth. 



On stones in a deep river, Island of Luzon, Philippines. Cuming. 



6. Navicella apiata (pi. cxvii. f. 14, 15. pi. cxviii. lis. 

 f. 39), Le Guillon, Rev. Zool. 1841, p. 376. 



N. testa rotundato-subtrigona, depressa, extiis obscure nigro 

 reticulata, epidermide fusca induta ; apice decumbente, marginem 

 superante ; iutus cserulea, nonnunquam macuHs nigris magnis 

 lateraHbus duabus ; septo subtrigono ; impressiouibus musculari- 

 bus rectiusculis. 



Much depressed and spread out at the sides, rather narrowed 

 in front, so as to give a somewhat trigonal form to the shell. The 

 septum is trigonal, and the muscular impressions straight and 

 narrow. 



Island of Bourbon. 



7. Navicella Cumingiana (pi. cxviii. f. 16, 17, 18), Reeluz, 

 Zool. Pro. 1842, p. 157. 



N. testa ovaK, convexa, sub epidermide concentrice nigro unda- 

 tim fasciata ; apice magno, marginem superante ; labio interuo in 

 medio producto; operculo subovaU, ad terminum bilobato; im- 

 pressiouibus muscularibus latis. 



This species, with the form of N.porcellana, and the produced 

 apex of N. macrocepliala and N. Luzonica, is remarkable for the 

 shape of the septum, wliich is curved outwards in the centre, 

 somewhat in the form of a uvula ; the operculum is also peculiar, 

 being rather oval, with two equal lobes at the end. 



Lebouka, Peejee Islands ; M. Farges. Islands of Mindinao 

 and Caminguing, Philippines ; on stones in a mountain stream ; 

 Cuming. 



8. Navicella Preycineti (pi. cxviii. f. 19, 20), Reeluz, 

 Rev. Zool. 1841, p. 375. 



N. testa ovali, convexa, sub epidermide angnlatim lineata ; apice 

 magno, marginem superante; labio interno in medio producto, 

 uvulseformi, quadrato ; impressiouibus muscularibus latissimis. 



Resembhng N. Siifreui, but having the septum still more 

 strongly uvulseform and the produced part squared. The muscular 



4 B 2 



