Mollusca of Lake Biwa. 
43 
Lithotis japonica, Preston. 
(PI. Ill, fig. I.) 
IQ16. Lithotis japonica, Preston, Ann. Mag. Nat. Hist. (8) XVII, p. 160, pi. ix, figs. 6, 6a. 
Colonel God win- Austen writes that he is very doubtful of the generic identity of 
this species with the Indian forms, which seem to be amphibious rather than strictly 
aquatic in habits. 
The Japanese mollusc is found clinging tightly to the lower surface of stones in 
shallow water. It is not uncommon at Chikubushima, and I took a specimen at Zeze 
near Otsu. A dead shell was also dredged in the middle of the southern part of the 
lake. The animal as a rule insinuates itself into small concavities on the surface of 
the stone in such a way that its shell fits close and becomes extremely inconspicuous. 
Family LIMNAEIDAE 
Genus Limnaea, Lamarck. 
Limnaea pervia, v. Martens. 
1879. Limnaea pervia, Kobelt, Abh. Senckenberg. nal. Ges. XI, p. 389, pi. xv, figs. 5, 6. 
1885. Limnaeus fervius, Mollendorff, Journ. As. Soc. Bengal LIV (2), p. 66. 
1886. Limnaeus pervia, Clessin in Chemnitz, Syst. Conch. Cab. (ed. Kuster) I, pt. XVII, Limnei- 
den, p. 388, pi. liii, fig. 6. 
This species appears to be scarcer in the vicinity of Lake Biwa than L. japonica. 
A small specimen was taken among weeds in shallow water in the southern part of 
the lake and a larger one in a ditch at Hikone 
The species was originally described from N. China and has been recorded from 
Tokyo (Yedo). 
Limnaea japonica, Jay. 
1879. Limnaea japonica, Kobelt, op. cit., p. 390, pi. xv, figs. 2-5. 
1886. Limnaeus japonicus, Clessin, op. cit., p. 382, pi. Hi, fig. 6. 
1887. Limnaeus japonicus, Mollendorff, op. cit., p. 66. 
I did not find this species in Like Biwa, but it is abundant in ditches and rice- 
fields at Hikone on the eastern shore and doubtless at other places in the neighbour- 
hood. 
It is known from Hokkaido and Shikoku as well as from the Main Island of 
Japan. 
Genus Choanomphalus, Gerstfeldt. 
1909. Choanomphalus, Lindholm in Korotneff's Wiss. Ergebn. Zool. Exp. Baikal-See IV (Mol- 
lusken), pp. 8, 93. 
The genus was at one time regarded as peculiar to Lake Biwa. According to 
Lindholm, however, it has also been reported from other parts of Siberia, from 
Thessaly and Macedonia, while there are species attributed to Planorhis from both 
western Asia and America that may possibly belong to it. 
