192 GASTEROPODA OF THE INFERIOR OOLITE. 
Body-whorl short, angular, concave, with a raised rim on the anterior margin, 
and a wide, depressed base. Aperture quadrate, columella short. In section (fig. 
11) the whorls are subrectangular, and nearly square ; columella and walls equally 
without folds. Other indications wanting. 
Relations and Distribution—In comparison with Pachystylus conicus, Gemm., 
this species is of somewhat larger habit, and its whorls are not quite so narrow. 
Coming nearer home one would suspect its relationship to Cerithiwm Defrancii, 
Desl. (Mém. Soc. Linn. Norm., vol. vii, p. 193, pl. viii, fig. 36), a fossil occurring 
in the Bathonian of France. 
Aptyxiella subconica has not hitherto been found out of the Parkinsoni-zone of 
Aston and Over Harford in the Eastern Cotteswolds. 
Genus—N srinwa, Defrance, 1825. 
General definition— Shell perforate or not; whorls numerous ; aperture sub- 
quadrangular, oval or elongate, with a short anterior canal or superficial notch ; lip 
forming posteriorly a narrow sinus, which leaves in passing off a narrow sutural 
band ; lines of growth strongly inflected near the suture; columella furnished with 
folds, which are internally persistent throughout its entire length ; other folds appear 
sometimes on the lip and the columellar side.” —Fiscusr, ‘ Manuel,’ p. 687. 
Before dealing with the question of the sections and subgenera of this most 
important genus a few remarks on its development in the Jurassics of this country 
may not be inappropriate. The following passage bearing on this point is quoted 
from ‘ Contributions to the Paleontology of the Yorkshire Oolites.”! 
“A peculiar interest attaches to the Nerinzas of the Inferior Oolite, since 
they are the earliest of their kind. The genus, we are told by Sharpe, usually 
occurs in calcareous strata associated with shallow-water shells. Thus we do not 
find Nerinzas in the Lias nor in the Striatulus-beds, nor even in the Dogger 
Sands. Indeed, I am not aware that any remains of the genus have been detected 
in the lower portions of the Dogger itself, such as the nodule beds which occur at 
intervals immediately above the Cynocephala-zone (Yellow Sands). But when we 
come to what was once the more calcareous portion of the Dogger, the shell-bed 
towards the top is so full of them as to have received the name of Nerinwa-bed. 
In this bed, only eighteen inches thick, the first noteworthy accumulation of 
Nerinzas occurs, nor are they ever plentiful again throughout the Yorkshire 
Oolites until we reach the Corallian Rocks. 
1 * Geol. Mag.,” decade iii, vol. i, p. 108. 
