Fig. 39.—Hislopia lacustris.
A=part of a zoarium of the subspecies moniliformis (type specimen, from Calcutta), × 15; A=green cysts in gizzard; E=eggs.
B=outline of part of a zoarium of the typical form of the species from the United Provinces, showing variation in the form of the zoœcia and of the orifice, × 15.
Polypide. The polypide has from 12 to 20 tentacles, 16 being a common number.
Type probably not in existence. It is not in the British Museum and Prof. Dendy, who has been kind enough to examine the specimens from Carter's collection now in his possession, tells me that there are none of Hislopia among them.
27 a. Subsp. moniliformis, nov.
Hislopia lacustris, Annandale, J. As. Soc. Bengal (new series) ii, p. 59, fig. 1 (1906).
In this race, which is common in Calcutta, the zoœcia are almost circular but truncate or concave anteriorly and posteriorly. They form linear series with few lateral branches. I have found specimens occasionally on the shell of Vivipara bengalensis, but they are much more common on the leaves of Vallisneria spiralis.
Type in the Indian Museum.
The exact status of the forms described by Jullien as Norodonia cambodgiensis and N. sinensis is doubtful, but I see no reason to regard them as specifically distinct from H. lacustris, Carter, of which they may be provisionally regarded as varieties. The variety cambodgiensis is very like my subspecies moniliformis but has the zoœcia constricted posteriorly, while var. sinensis, although the types were found on Anodonta shells on which there was plenty of room for growth, resemble the confined phase of H. lacustris so far as the form of their zoœcia and of the orifice is concerned.