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DESCRIPTION OF THE SPECIES FIGURED 
Luctna suseLoposa, n. sp. PI. IV., fig. 1 
Shell orbicular, globose, umbones tumid, mesial, curved, 
hinge margin nearly straight, oblique, lunule moderately large, 
concentric folds regular, nearly flat, having fine longitudinal 
striations. The thickness through both valves is equal to two 
thirds of the lateral diameter, height and breadth each ten 
lines. : 
The concentric folds resemble those of LDucina Bellona, 
D’Oxs., with which it is found, and it may possibly be a variety 
of that species, but it is very much smaller, is more globose in 
comparison with its diameter, and is destitute of the oblique 
obscure elevation from the umbones to the inferior and posterior 
border, which is one of the characteristics of that species. 
Locality.—Tiltup’s End, near Nailsworth, in the White 
Limestone (Great Oolite.) 
Nerin#a compiicata. n.sp. Pl. IV., fig, 2, 2a 
Shell very long, slender, conico-cylindrical, upper whorls 
concave, ornamented with five transverse minute ribs; the 
lower whorls gradually become flatter and smooth—the last 
few whorls thickened at the suture, which gives a slight con- 
vexity to the whorls. Columella solid, with three folds, the 
anterior fold bifurcated, the anterior branch of the bifurcation 
angulated, or slightly bifurcated; the middle fold angulated, 
the posterior fold bifurcated, there is also a small fold, some- 
times scarcely visible, on the posterior wall. The outer 
wall has three principal folds, the upper or posterior fold is 
simple, the middle fold is sharply angulated and broad at the 
base; the anterior fold is also broad, and is more produced 
anteriorly. There is also a minute fold between the upper and 
middle principal folds; aperture sub-quadrate; length about 
five inches. The diameter of the whorls is slightly greater 
than the height. 
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