3o8 
ZOOIvOGY OF THE FAR EAST. 
Locality. Tai-Hu (Great Lake), Kiangsu Province, China. 
The species is closely allied to B. humida, but is distinguished by its smaller size, 
the colourless shell with well defined microscopic sculpture, the last whorl not 
projecting and the oval aperture. 
My specimens were dredged in 3 metres of water from a muddy bottom without 
weeds but with a certain amount of decayed vegetation. They were taken in 
large numbers. The exact position was a little N.E. of the island Si Dong Ding. 
The species was not obtained at other dredging stations. 
Genus Stenothyra, Benson. 
The species of this genus, which are probably numerous throughout the coastal 
districts of southern and eastern Asia, are imperfectly known so far as China is con- 
cerned. Heude {op. cit., p. 173) figures only one (S. towc^^awa) from the Yangtse 
valley. He expresses the opinion, however, that there are a considerable number 
of species on the coast of China. The genus is usually estuarine, at home in brack- 
ish water and water of variable salinity. The only species we obtained in the Tai-Hu 
is well characterized by the strong sculpture of its shell. 
Fig. 2. — Radular teeth of Stenothyra decapitata, sp. nov. 
Stenothyra decapitata, sp. nov. 
Shell small, solid, broadly spindle-shaped, probably blunt at the apex when per- 
fect, always eroded, with not more than 3^ whorls remaining, pale flavous or olivace- 
ous, sometimes stained dark chocolate-brown, translucent, smooth but not highly 
polished, ornam.ented with numerous (about 20 on the body-whorl) spiral rows of 
minute punctures, with still more minute spiral striae between the rows. Suture im- 
pressed, whorls somewhat inflated. Body-whorl obesely elongate, more than twice 
as long as spire, slightly flattened on the ventral surface, subumbilicate. Aperture 
prominent, surrounded by a well-defined rim, subcircular, relatively large. 
Operculum thick but horn}^, brownish or yellowish, polished on the external sur- 
face, with well-marked spiral striae, with the nuclear region concave and occupying 
more than a third of the whole. 
Radula very like that of 5. toucheana as figured by Heude and Rathouis {op. cit., 
pi. xxxii, fig. 13) but with 5 instead of 3 upper denticulations on the central tooth, 
the lateral teeth narrower and the inner lateral tooth with the denticulations better 
developed. 
