3o6 
ZOOLOGY OF THE FAR EAST. 
There is, further, a certain difference in shape, some being more elongate than others, 
but this difference is perhaps sexual and cannot be correlated with locality. The 
specimens from Mukden are the largest and agree well with Heude's figures of his B. 
chine nsis. 
B. striatula is not uncommon among stones at the edge of the Tai-Hu. It also 
occurs in canals at Soochow. 
Bythinia longicornis, Benson. 
1842. Paliidina (Bithynia) longicornis, Benson, op. cit., p. 488. 
1855. Paliidina (Bithynia) longicornis, id., op. oil., p. 130. 
1882. Bithynia longicornis, Heude, op. cit., p. 171, pi. xlii, figs. 4, ^a-b. 
There are three co- types of Benson's species in the collection of the Zoological 
Survey of India and I have recently examined a number of specimens from Suigen in 
Corea {T. Kawamura) which agree closely with them. Specimens taken with those 
of Bithynia striatula in the Tai-Hu and at Soochow differ from the co-types in being 
considerably smaller (not more than 7 mm. long by 5 mm. broad) and in having their 
apices eroded, but are otherwise similar. The species is abundant in the Tai-Hu 
district, and is stated by Heude to be "banale dans les eaux lacustres de toute le 
vallee du Yang-tze qu'elle suffirait pour characteriser paleontologiquement, si le sol 
pouvait la conserver." 
Genus Hypsobia, Heude. 
1882. Hypsobia, Heude, op. cit., p. 173. 
1915. Katayama, Robson, Brit. Med. Journ., No. 2822, p. 203. 
I cannot discover any difference between Heude's Hypsobia and Robson' s Kata- 
yama. The structure of these molluscs is unusually well known, for Heude figures 
the radula and operculum and reproduces certain details of the soft parts, while Rob- 
son gives sketches of the radula and operculum. 
Type-species. — Hypsobia humida, Heude and Rathouis. 
Geographical Distributio7t. The valley of the Yangtse and parts of the Main Is- 
land of Japan. Including a new species to be described here, three species are 
known, namely H. humida found " in alto districtu Tche7i-k'eou " in the upper Yangtse 
watershed, H. minuscula, sp. nov. from the Tai-Hu and H. nosophora from the Bingo 
province of Japan. 
H. humida and H. nosophora are found in damp places, the latter at the edge of 
water-channels and other small bodies of water, while my new species was dredged 
from the bottom of the lake. H. nosophora appears to be the main if not the 
only carrier of Schistosomiasis^ in Japan. It is fortunately very local in distribu- 
tion. Both it and H. minuscula are markedly gregarious. 
Key to the known species of Hypsobia. 
I. Shell more than 7 mm. long, of a brownish colour, with the aperture 
ovoid, not much longer than broad ; irregular growth-lines crossing 
the finely granular surface, a faint microscopic spiral sculpture . . H. fiosophora. 
1 See Katsurada, Annot. Zool. Japan, V, p. 147 (1904) and Leiper Brit. Med. Journ., No. 2822, p. 202 (1915). H. 
nosophora is known in Japan as Blanfordii nosophora, Pilslong (or Robson). See Journ. Parasitology III, No. 4, Notes 
(1917)- 
