SUPPLEMENT. 489 
umbilical furrow. Number of whorls five to six. These are very tumid and 
separated by a deeply impressed, almost canaliculate suture; sutural angle very 
oblique. No ornamentation, other than growth-lines, which are rugose and 
varix-like on the body-whorl. Aperture nearly circular with thin sharp lips. 
Relations and Distribution.—This species resembles in some respect Paludina 
scotica, which occurs in the Hebrides on approximately the same horizon. It also 
differs but little from Paludina vivipara, being perhaps of smaller habit and with 
a more sloping sutural angle and more convex whorls than the existing species. 
On the other hand the Paludinas of the Upper Purbeck are for the most part 
very different. 
Paludina Langtonensis is abundant in the so-called Paludina-bed, a kind of 
mortar-like deposit which occurs high up in the Chipping Norton limestone at 
Langton Bridge, along with other freshwater species and occasionally seeds of 
Chara, &e. But associated with these are species of Cerithiwm and Nerinea along 
with a small variety of Amberleya nodosa—apparently a Bathonian fauna. This 
deposit, where developed, is found to underlie a gritty bed containing teeth and 
palates of fish. 
Paludina Langtonensis also occurs in great abundance at Castle Barn, three and 
a half miles from Chipping Norton, and traces may likewise be seen at Sharp’s 
Hill in a similar position. 
Genus—Vatvata, Miller, 1774. 
Shell wmbilicated, turbinoid, or subdiscoidal, spire but slightly prominent, whorls 
conver and few; aperture circular, oblique ; peristome entire, thin, sharp, slightly 
expanded. 
449, VaLvaTa CoMES, sp.nov. Plate XLIII, fig. 27; and Plate XLIV, figs. 2 a, 2b. 
The transverse diameter of these little shells does not exceed 3mm. Judging 
from the figure they differ slightly from Valvata precursor, Tate (‘ Quart. Journ. 
Geol. Soe,’ vol. xxix, p. 348, pl. xii, fig. 9). The’spire is more salient than in 
Valvata cristata. 
Somewhat rare in the Paludina-bed at Langton Bridge. 
