488 GASTEROPODA OP THE INPERIOR OOLPFE. 



eacli successive wliorl. The body-whorl occupies one third of the total height, 

 and is somewhat bicarinate. All the whorls, including the body-whorl, are 

 slightly convex and very smooth. The aperture is quadrate, with a short thick 

 columella, and wide anterior notch. A fold on the inner and outer walls of each 

 whorl. 



Relations and Distribution. — This species belongs to the biplicate section of 

 Nerinella (see p. 198, and PL XIII, figs. 1 and 2, of this Monograph). It is much 

 broader than either of the two unnamed forms there described. Consequently the 

 shape of the whorl in section is much more squat. 



There are two specimens in my Collection from the Lincolnshire Limestone of 

 Weldon, and others which seem to connect with the narrower forms. 



447. NeeiNzEA (Pttgmatis) cf. cingenda, Phillips. Plate XLIV, figs. 8, 8 a, 8 h. 



Specimens of an elongate Neringea, not unlike N. cingenda, occur somewhat 

 plentifully in the Lincolnshire Limestone at Stoke Lodge. In this case the 

 internal section is that of a Ptygmatis with five folds. The specimens greatly 

 resemble a variety provisionally named ^^ pseudocingenda " (see p. 212, PI. XIV, 

 fig. 15, of this Monograph). Bearing in mind that sections of Dogger specimens 

 of Nerinsea cingenda are liable to mislead, the Stoke Lodge fossils may possibly 

 represent the true internal structure of this species. 



Genus — Paludina, Lamarch, 1812. 



Shell turbinated loitli round whorls, thin ; aperture circidar, slightly angidar 

 behind, peristome continuous, entire ; operculum horny, concentric. 



Conchologists have expressed a doubt whether Paludina extends as far back 

 as the Jurassic. Yet Paludina occurs abundantly in the Upper Purbecks. 

 Neither can we doubt that Paludina scotica, Tate (' Quart. Journ. Geol. Soc.,' 

 vol. xxix, p. 349, pi. xii, fig. 3), from the Infra- Oxfordian beds of Loch Staffin, 

 is correctly referred to that genus. 



448. Paludina Langtonensis, sp. nov. Plate XLIV, figs. 1 a, 1 b. 



' Description : 



Height (full size) . . . .30 mm. 



Body- whorl to total height . . . 60 : 100. 



Spiral angle ..... 62°. 

 Shell smooth, turbinate, often rather dark in colour, and with a considerable 



