11 
PALUDINA elongata. 
(Gen. Yivipara, Yol. i. p. 75.) 
TAB. DIX.— figs. 1 and 2. 
Spec. Char. Ovato-lanceolate, smooth ; volutions 
5, convex ; aperture elongated. 
Well distinguished from the other species of Paludina 
by its great length, which equals twice the diameter : it 
resembles the recent species common in fresh water 
every where (Helix tentaculata Linn.), but is larger and 
even longer in proportion than that is. 
When Yivipara Fluviorum (Paludina vivipara of La- 
marck) was published in Mineral Conchology, it was not 
known that fresh-water formations were to be found be- 
low the Chalk ; nevertheless the probability of one was 
pointed out by that shell. The existence of several spe- 
cies of Paludina, of bivalved shells belonging to the 
fresh-water genus Cyrena, and of Cypris, in the strata 
between the Green-sand and the Portland Rock, indicate 
this range to be of fresh-water origin. (See Dr. Fitton’s 
paper in the Ann. of Phil. vol. viii. N. S. p. 379; and Mi- 
neral Conchology, vol. v. p. 138. tab. 485. Cypris.) 
Dr. Fitton has favoured us with specimens out of the 
Weald Clay, in hard ferruginous clay ( u Clay-Iron- 
stone”), from Compton Grange Chine in the Isle of 
Wight. Most generally only the cast of the shells re- 
mains, but in that selected for representation the shell is 
preserved (fig. 2.): it is accompanied with Cyrena and 
Cypris. The same shell also occurs less perfect in la- 
minated Clay and in u irregular concretional masses of 
hard calcareous grit in the latter the shells are often 
filled with sulphate of barytes. 
We have taken fig. 1. from a mass of Limestone, 
upon the surface of which the shells are tolerably per- 
fect, although within they appear to be crushed (a cir- 
