Mollusca of the Tai-Hu. 
313 
valde caducis circumcincta ; spira acuta, anfractibus 7, planulis, sutura scalar i junc- 
tis ; ultimo ad peripheriam confuse angulato ; apertura vix obliqua, ovali ; peris- 
tomate acuto margine columellari brevissimo, nec incrassato, nec dilatato, aliquan- 
tulum sinuoso ; umbilico angusto, bene perforato, in canalem columellarem margine 
carinatum producto. Altit : 5^; latit : 4^ millim." 
Shells from the Tai-Hu and from the Whangpoo near Shanghai vary greatly in 
size and shape. The following measurements (in millimetres) are those of specimens 
from the lake. 
The external surface of the shell when not eroded is of a deep horn-colour. The 
inner surface is polished and of much the same colour, except immediately round the 
aperture, where it is whitish. When the epidermis is worn away fine longitudinal 
striae appear on the shell. 
I can detect no constant difference between specimens from the river and those 
from the lake. In both localities the species is quasi-aquatic rather than aquatic, 
adhering in large numbers to damp stones just above the water-line. At the edge 
of the Whangpoo it is found with A. haematina, Heude, which is, however, much less 
abundant and apparently not gregarious. A. scalaris was described from " parietes" 
near Shanghai. It evidently resembles the Indian A . francesiae, Gray in habits and, 
like that species, makes its way for a considerable distance inland in estuarine tracts, 
well beyond the limits of brackish water. 
The genus is represented in the Tai-Hu by a large species of the V. chinensis 
group and also by a dwarfed form of a species belonging to a curious and interesting 
group the first member of which to be described was V . angulata (Miiller). The 
perhaps more characteristic V . quadrata (Benson) and a number of closely related 
species or races figured by Heude also belong to the group, which is found widely 
distributed in the watersheds of the Yangtse and the Canton river. The shell is 
characterized by the more or less irregular and inconstant spiral ridges and coarse 
longitudinal striae with which it is ornamented. These peculiarities are, however, 
much less accentuated than in the western Chinese genus Margarya, Nevill, in which 
the shell is also much larger and thicker. 
Vivipara lapillorum (Heude). 
1882. Paludina lapillorum, Heude, op. cip., p. 177, pi. xl, figs. 11, iia. 
1909. Vivipara lapillorum, Kobelt, Paludina in Chemintz's Conch. -Cab. (ed. Kiister), p. 122, 
pi. XXV, figs. 14-17 (lapillosa). 
Kobelt regards this species as no more than a variety at most of Benson's 
Paludina quadrata, but it differs from all the forms that can be legitimately assigned 
Length. 
5-5 
47 
5-2 
Breadth 
4-0 
375 
3-5 
Aperture. 
275 X 2'0 
2-5 xi-5 
2-5 xi-5 
Family VIVIPARIDAE. 
Genus Vivipara, Lamarck. 
