Zoological Society. 277 



pressis ; apice compresso-concavo ; aperturd orhiculari, subconliniKi, 

 ifitus albidd ; labia latissimo, depresso-jjhmOyfi/sco-aunoitio, mar- 

 gine subarcuato, edentulo ; labio rotundato, superne et in/erne 

 dilatato. 

 Var. /3. Testd nigrescente, immaculatd. 



Long. 1-52; lat. 1-84; conv, 1-04 poll, Aperturse altitudo 1-52; 

 lat. 1-60 poll. 



Hub. Ad Insulas Philippinas ; Tanhay, isle of Negros : in a small 

 river. Var. /3, Agoo, province of Pangasinan, isle of Lugon : on 

 stones in a rapid river. 



Two pyriform muscular impressions, and more forward than in any 

 other species, are visible at the interaal base of the columella, which 

 has no trace of callosity. 



The upper tooth of the operculum is oblique, lamellated, with a 

 strongly-cut crest, a character which is unique in the genus Nerita. 



2. Nerita squam^picta. N. testd ovato-subhemisphccricd, supra 

 medium vix depressd, striis longitiuVuialibus remotis superne et un- 

 tice subarcuatis impressu, sub epidermide olivaceo maculis squami- 



formibus cintice nigro-marginatis undique pictd ; apice rotundato- 

 obtuso ; aperturd extiis ovatd, intiis albido-carulescente ; labio 

 piano, lutescente, medio albo, a7itice tenue arcuatim denticulato. 

 Long. 1-16 ; lat. 1-44; conv. 0-88 poll. 



Hub. Agoo, province of Pangasinan, isle of Lu^on : in a rapid 

 river. 



Operculum similar to the Nerites, allied to A''. puUigera ; subcon- 

 vex above, finely striated lengthwise, of a whitish fawn-colour pos- 

 teriorly ; rosy anteriorly, streaked with circular bands of a blackish 

 blue ; subconcave below, of a dirty green, spotted with rosy white 

 at the anterior side. Two teeth : the upper one ovate, acute at the 

 summit, reddish ; the lower one circular, canallculated lengthwise, 

 feebly striated transversely, yellowish. 



3. Nerita Petiti, Recluz, Rev. Cuv. 1841. p. 274. No. 24. 

 Var. /3. T. majori,fusco-castaned; infime et superne ad suturam com- 



pressd et subcanaliculatd ; spird retusd. 

 Var. y. T. minori, fusco-nigrescente, sub oculo et lumine tnacuUs 

 nigris diver siformibus notatd ; aperturd subrotu?idd, superne et in- 

 ferne dilatatd, intiis aurantid. 

 Long. 1-40; lat. 1-96; conv. MG poll. 



Hab. Cagayan, province of Misamis, island of Mindanao : on 

 stones. Var. y, Agoo : in a mountain-stream. 



The operculum of this species differs from that of N. pulligera 

 only in its paler colour. 



4. Nerita asperulata. N. testd ovafo-ellipticd, striis intertextis 

 granulosis asperulatd, fusco-nigrd, sub oculo et lumine, lineis ni- 

 gris ramosis transversis intricatis notatd ; anfractibus l^, superne 

 depressis ; apice prominulo, obtuso ; aperturd rotundatd, superne 

 et inferne dilatatd, luteo-fuscescente ; labio plano-comjiresso, mar- 

 gine vix arcuato et tenue ruguloso. 



Long. 0-56 ; lat. 0-76 ad 0-84 ; conv. 0-40 ad 0*44 poll. 



