17. Neritina Beckii (pi. cix. f. 13), Recluz, ilev. Zool., 

 1841, p. 275. 



N. testa N.pnlligera simili, sed nigra; labio externo ad apicem 

 decumbente, labio interuo subconvexo. 



Besembling iV. pulUgera and N. Knorrii, but differing from the 

 former in the absence of the raised ridge on the apex, and from 

 both in the columella being rather convex. The outside is black, 

 and the margin of the outer lip is banded with deep orange. 



18. Neritina canalis (pi. cxi. f. 75, 76), Sowerhy, senr., 

 Tank. Cat. no. 1094. Conch. HI. f. 22. 



"N. testa ovata; spira brevissima, obtecta; labio externo in 

 canalem ad sinistram inclinatam producto ; labio columellari auran- 

 tiaco, obsolete subdenticulato ; epidermide nigerrima." 



Of the same form as N. pulUgera, but the left side of the inner 

 lip not at all callous. The epidermis is very thick and black ; 

 there is a curve in the upper part of the outer lip, which is raised 

 into a ridge at the apex ; there is a grove between the outer bp 

 and the upper part of the columella. 



Tahiti ; on stones in a rivulet. Cuming. 



19. Neritina Bruguieri (pi. cxiv. f. 159), Recluz, MS. 

 Mus. Cum. 



N. testa N. canali simillima, sed transverse magis elongata ; 

 labio externo supeme undato, ad apicem decumbente. 



Longer in the transversely oblique direction than N. canalis ; 

 the upper margin of the outer lip has a sinus or undulation, as in 

 that species, but is not raised in a ridge on the apex. 



New Ireland ; on small stones in a rivulet. Hinds. 



20. Neritina asperulata (pi. cxiv. f. 160, 161), Recluz. 



N. testa transverse ovali, scabrosa, epidermide crassa, fusca, 

 induta ; spira complanata, sublaterali, anfractu singulo ad suturam 

 carinato ; apertura magna, pallide aurantia ; labio externo intus 

 incrassato ; labio interno septiforme, complanato, margine edentulo. 



Transversely oval, finely scabrous, covered with a thick brown 

 epidermis ; with the spire flattened and lateral, consisting of one 

 whorl, which is keeled at the suture. The aperture is large, of a 

 pale orange colour, with the outer lip thickened inside, and the 

 inner lip septiform, with a smooth edge. 



" On small stones in a rivulet, Island of Luzon." Cuming. 



