334 GASTEROPODA OF THE INFERIOR OOLITE. 
Bibliography, Sc.—This species or variety was first noticed by Phillips, who 
referred it to the Nerita costata of the‘ Mineral Conchology.’ D’Orbigny re-named 
it N. pseudo-costata, and by that name this rather abundant Dogger shell has gene- 
rally been known to British paleontologists. Not quoted in the ‘ Terrains Juras- 
siques.’ 
Description.—The width and height are nearly equal, the height of a full-sized 
specimen being about 9 mm. In other respects the shape of the shell as in the 
preceding species. ‘The flanks of all the whorls are ornamented with very strong 
radial cost, regular, and separated by sulci about twice the width of each rib. 
Relations and Distribution.—This form can be regarded as little more than a 
variety of the preceding species, somewhat less transverse in shape, and with 
stouter and fewer ribs. It replaces N. costulata in the Yorkshire Dogger, and occurs 
very sparingly in the Pea-grit of Crickley. It is not improbable that Nervita 
costifera, Piette, from the Bathonian of Rumigny, is a micromorph of this species 
on a higher horizon. 
267. Nerita suBRUGOSA, sp. nov. Plate XL, figs. 7a, 7 b, 8. 
Description : 
Height : ; ‘ : 8 mm. 
Width ; “ 9°3 mm. 
Shell transversely ovate, angulated, rather higher than wide, thick ; spire short, 
few-whorled, whorls sunk inadeep channel. Body-whorl relatively large, flattened 
and angulated posteriorly, and provided with a carina of moderate salience, 
which is situated rather above the middle of the whorl. Coste fine, regular, and 
numerous, and exhibiting slight nodes on crossing the median carina. Aperture 
very wide, columellar area flattened ; other indications wanting. 
Relations and Distribution.— Nerita subrugosa is a form imtermediate between 
Nerita costulata, Desh., and Nerita rugosa, Morris and Lycett. From the former it 
differs in its more angular outline, in the development of a median carina, and in 
the finer and more closely-set costa. 
The specimen figured (Plate XXVIII, fig. 6) in the present work, from the 
Scarborough Limestone, probably represents a sort of a passage between N. cos- 
tulata and N. subrugosa, where there is a very slight tendency to a median carina. 
On the other hand, Nerita rugosa, M. and L., is less transversely ovate, has a higher 
spire, and the median carina is much more strongly developed; it is in fact 
altogether a coarser shell. 
Nerita subrugosa has been found sparingly in the Scarborough Limestone at 
