428 Journal of the Asiatic Society of Bengal. [N.S., XIX, 1923.] 
biological conditions under which these bivalves live along the 
margins of the Lake. a far as I am aware these conditions 
have not been properly studied and my conclusions are only 
derived from the study of ee shells before me. 
Measurements (in millimetres) :— 
i 2 3 4 5 6 
Length cc Ae “24 20 2] 206 1878 
Height . 24 25 | «205 20 204 16:7 
Diameter «. 18S IG 4 149 15:2 116 
Corbicula sp. 
A single valve from the Yung-Chang, a tributary to the 
Salween River, agrees with C. conica Heude (loc. cit., Fig. 16), 
but with only a single valve it is impossible to be certain as to 
its identity. 
Genus Sphaerium Scopoli 
I have not succeeded in tracing any record of the occurrence 
of this genus in Yunnan, and it is, therefore, of interest to note 
that a single left valve of a species of this genus was coliected 
by the Perey Sladen Expedition near Shang-Kuan on the 
north-western shores of the Lake Tali. I do not propose des- 
cribing the species from the single valve, but it may be noted 
that the species appears to be allied to the Indian species of the 
genus. 
