Mollusca of the Tai-Hu. 
307 
2. vShell about 4 mm. long, pale horny, nearly smooth ; aperture pyri- 
form, considerably longer than broad .. .. .. H. humida. 
3. Shell less than 3 mm. long, transparent, colourless, ornamented with 
minute serrated spiral ridges interrupted by longitudinal striae ; aperture 
oval, considerably longer than broad . . . . . . . . H. minuscula. 
I have not seen H. humida but have examined a series of shells of H. nosophora. 
Hypsobia minuscula, sp. nov. 
Shell minute and fragile, colourless, transparent, shining, slightly iridescent, 
hardly subumbilicate, probaby with seven whorls when complete, but always eroded 
at the tip. Whorls increasing gradually, somewhat inflated ; body- whorl not mark- 
edly projecting ; suture impressed, not markedly oblique. Sculpture consisting of 
numerous minute serrated spiral ridges interrupted at frequent and irregular intervals 
by oblique longitudinal striae in such a way as to give the surface a reticulate appear- 
ance under a high power of the microscope. Aperture oval, oblique, relatively large, 
Fig. I. 
A. Mouth of shell of Hypsobia minuscula, sp. nov. (Highly magnified). 
B. External view of operculum of same species. (Still more highly' magnified). 
C. Mouth of shell of Hypsobia nosophora (Robson). (Less highly magnified). 
with its anterior extremity not at all pointed. Outer lip sometimes slightly intro- 
verted in the middle ; columellar lip delicately expanded and rimate. Columella 
strongly arched. Operculum like that of H. humida and H. nosophora but broader, 
hyaline, brittle and very thin, with fine transverse, striae running outwards from the 
suture and interrupted by two parallel spiral grooves on the external surface. 
In spite of the thinness of the operculum the spirit in which my specimens were 
preserved has not penetrated it and the soft parts are in rather bad condition. The 
eyes are very small ; the tentacles thin, tapering and .short, marked with dark 
pigment. The snout is narrower than it is shown in Rathouis's figures of B. humida 
published by Heude. The penis is blunt, simple and rather short. The ovaries are 
well developed in female specimens. 
Greatest length of shell 2 '5 mm. Greatest breadth 073 mm. L,ength of aperture 
0*85 mm. Breadth of aperture 0-42 mm. 
Type-specimen. M. 10460/2, Zool. Survey of India {Ind. Mus.). 
