BULLEN : SUMATKAN LAND AND FKESH-WATEE MOLLUSCA. 



129 



13. Pterocyclus aspersus, n.sp. 



Testa discoidalis, aperte umbilicata, ad apicem subelata, sordide 

 albida, supra fusco-purpureo tincta ; anfractus 4^ satis rotuiidati, 

 sutura profunda discreti, striis incienienti obliquis sculpti, ultimus 

 antice descendens ; peristoma dupk'x, margine exteriori late expanso, 

 tenui, albo, continue, anfractui eunjuncto, interne tenui, continue ; 

 operculum corneum, tenue, spiraliter carinatum, anfractibus circiter 

 9 transversim striatis. Diam. maj. 19, min. 14"5mm. ; alt. 9 mm. 

 Apertura intvis 6 mm. 



Hab. — Loeboek Bangko. 



The adult specimens are denuded of periostracum, and are coloured 

 as described above, but an immature specimen consisting of three 

 whorls and probably belonging to this species, is yellowish, copiously 

 blotched above and below with rich brown markings, and it also exhibits 

 a somewhat broken-up peripheral zone. Under a strong lens the 

 protoconch is beautifully spirally punctate. The centre of the 

 operculum, which is concave, is also very finely spirally striated. 



14. Leptopoma Fultoni, Aldrich. 



Hah. — Bongsoe. 



Hab. 



15. ISIDOEA (BULINUS) SuMATRANA, VOU Marts. 



-Mount Ophir. 



Four examples possess seven whorls, and are large and well 

 developed ; four possess six only, and two of these are stunted 

 specimens. 



16. Planorbis Sagoensis, n.sp. 



Testa orbicularis, depressa, subcarinata, pallide luteo-cornea, lineis 

 incrementi obliquis timnibus sculpta ; anfractus 3^ superne convexi, 





inferne sub-convexi ; apex depressus ; umbilicus satis depressus 

 apertura oblique lunata, ad peripheriam subangularis. Diam. max. 6 

 min. 5 mm. ; alt. 2 mm. 

 Hab. — Mount Sago. 



