1076 
MA.LAYSIAN LAND AND FRESHWATER MOLLUSCA 
Fig. 4. Eaclula of do. — A, central tooth ; B, lateral tooth ; 
first marginal tooth ; D, secontl marginal tooth. 
Fig. 5a. Portion of one of the mandibular plates (veiy much 
enlarged). 
Fig. 5b. Details of do., on a much larger scale. 
Figures 1, 2, 3 are magnified two dianietei's. 
Hybocystis elephas, De Morgan, Le Nat. VII. 1885, No. 9, 
p. 70 ; von Moll. Jour. As. Soc. Beng. LV. 1886, p. 314. 
Perak. 
H. JOUSSEAUMEi, De Morgan, l.c. p. 70 ; von Moll. Lc. p. 315. 
Valley of the Plus river. 
Family HYDROCENTDxE. 
33. Georissa, Blanford, 1864. 
Aun. and Mag. Nat. Hist. 3rd series, XIII. 1864, p. 463 ; ibid. 
4th serie.s, III. 1869, p. 173. 
Type Hydrocena pyxii, Benson. 
Shell resembling that of Hydrocena, imperforated, small, conical, 
umber or reddish-coloured, spirally sulcated or striated. 
Animal furnished with hemispherical lobes in the place of tenta- 
cles ; eyes normal ; foot short, rotund. Operculum semi-oval, no 
spiral structure as in Helicina ; excentrically striated, testaceous, 
transparent. 
Georissa monteros.atiana, Godwin-Austen and G. Nevill, 
Proc. Zool. Soc. 1879, p. 739, pi. 59, fig. 6 ; von Moll. Jour. As. 
Soc. Beng. LV. 1886, p. 316. 
Bukit Pondok. 
G. SEMISCULPTA, Godwin- Austen and G. Nevill, l.c. p. 740, 
pi. 59, 6g. 3, 3« ; von Moll. l.c. p. 316. 
Bukit Pondok. 
