408 Journal of the Asiatic Society of Bengal. |N.S., XUX, 
Vivipara quadrata (Benson). 
(Plate 17, Fig. 2). 
1842. Paludina quadrata, Benson (under Cantor), Ann. Mag. Nat. Hist., 
87 
1877. Paludina angularis (in part), Nevill, Cat. Moll. Ind. Mus , E., p. 31. 
J 

This appears to be the common Vivipara of China. It has 
many forms, which in large series can often hardly be distin- 
guished, and seems to be in much the same ev olutionary state 
as bengalensis. Many authors have confused it with JV. 
angularis (Muller),! but it differs in the consistency of the shell, 
which is always much more porcellaneous. in its less conical 
ceca. in its thinner and sha arper columellar fold and especially 
in the sculpture of the shell, which always shows traces of spiral 
ridges but has never the three sharp, clean-cut ridges on each 
whorl (above the periphery of the body-whorl} referred to by 
Miller in his original description. The two species both occur 
at Canton, from the rivers appipsoning. which V’. angular's was 
originally described. Photographs 1, 2 on Plate 17 illustrate 
these differences clearly. 
The typical form of quadrata (Plate 17, Fig. 2) from 
S.E. China is very elongate and often almost subevlindric ahs 
it varies, however, both in shape and size; its distinctive 
character is the vertical flattening of the whorls to which Benson 
referred i in his specific name. This feature is much less marked 
in other forms of the species. I do not understand Benson’s 
statement that the eves are on pote while in other ae 
they are sessile. 1 can, indeed, see ifference in this respect 
in the forms of which I have gad the animal, except that 
the pedicels are perhaps a little narrower in the Chinese than 
in the Indian and European forms. 
In the collections from Yunnan which I have examined 
there are no specimens of the typical! form of the species, but 
three forms are present which are sufficiently distinct to be 
given names, although intermediate individuals occur both 
between them and approaching the forma typica. These I call 
minor (Nevill), dispiralis (Heude) and limnophila (Mabille). 
My V. margaryoides seems to be specifically distinct although 
allied to the form dispiralis. The reticulate shell sculpture is 
particularly characteristic. 
Form minor (Nevill), 
(Plate 17, Fig. 5). 
i885. “Mw. aeruginosa var. minor, Nevill, Hand List Moll. Ind. 
us » Pp. eee 
| Ner ita wiaians is, , Miller, 1 Hist. ia. p. 187 iit See also 
Walker, Nausilue XXXII, p. 114, Plate VIII, Figs 4,5 (1919 
—— ee 

oa ee ee CC er en 
