22 
SHARPE proposed, many years ago, to subdivide the genus 
into four sub-genera, distinguished partly by the number of 
internal folds, and partly by the nature of the columella; but 
this subdivision has not been followed by continental, and only 
partially by English paleontologists. 
The advent in the Inferior Oolite of this country of this 
interesting genus of the gasteropoda was distinguished by 
several species, all of which are found in the Cotteswolds,* and 
one of them in the Yorkshire Dogger. They first appear in 
the Pea Grit, or rather the Pisolitic Limestone of that forma- 
tion, and three species are confined to these beds, where they 
are especially abundant. 
In the building Freestone, at Swift’s Hill, near Stroud, 
there is a marly limestone bed not far below the Oolite Mazrl, 
which comprises the second Nerinewa zone. In this bed several 
species have been found. In the Oolite Marl there is another 
marly limestone bed, which, at Rodborough Hill, contains 
N. Cotteswoldie in abundance; and along the side of the 
Nailsworth valley that species and. others more rare have been 
found by Lycnrr, and described in the “ Geology of the Cottes- 
wold Hills.” Above the Oolite Marl the genus does not occur 
in the Inferior Oolite of the Cotteswolds, so far as I have 
ascertained, except in the Clypeus Grit. In the fossiliferous 
zone of the Clypeus Grit at Rodborough there are three species, 
one of which, N. Guisei, Wirc., is tolerably abundant. This 
species has been found in beds on the same horizon in the 
neighbourhood of Sodbury, and has been traced by Mr W. H. 
Hupueston, F.R.S., as far as Radstock, but the genus has not 
hitherto been found south of that area. On the top of the 
Clypeus Grit at Notgrove, associated with fragments of Coral 
and other detritus, indicating a period of denudation, Mr 
Watrorp has found the internal moulds of three or four species 
* This is assuming that Dr WRIGHT is correct in his identification of 
NV. cingenda, stated by him to occur in the Pea Grit at Leckhampton. Vide 
Q. J. Geo. Soc., Vol. XVI., pp. 11, 13. It does not appear to have been 
found elsewhere in the Cotteswolds. It is abundant in the Nerinwa bed of 
the Dogger. 
