NERIN AA. 223 
posterior marginal rim. No signs of spiral ornamentation have as yet been 
detected, though we should expect fine spiral lines in the apical whorls. 
The body-whorl is short, flat or searcely hollowed, and angular. The aperture is 
subrhomboidal, and where the specimens are complete or nearly so (fig. 3 a) there 
is no trace of the folds which are so conspicuous in the section of the spire.' Canal 
short and moderately reflexed. The section exhibits six folds, some of which are 
very complex. On the outer wall the anterior fold is very wide, and has three or 
four small angular indentations, whilst the posterior fold is small and deep, but 
almost simple. Of the three folds on the columella the lower one is the largest 
-and square-headed; the fold on the posterior wall occupies a large space and 
bifurcates unequally. Altogether the space for the animal in the whorls of the 
spire must have been excessively small, and specimens, especially from the 
Lincolnshire Limestone, when cut longitudinally, exhibit very whimsical figures. 
There are indications, however, that this system underwent modification in the 
later whorls, and that possibly it was non-existent in the body-whorl. But other 
interpretations of these appearances have been suggested. 
Var. contca, Witchell. 
1887. Nerina contca, Witchell. Op. cit., p. 30, pl. i, fig. 2. 
Description : 
Spiral angle : : : ao Be. 
Height of whorl to width : : » 1 21°85. 
Length : 3 . 75 mm. 
In the apical whorls there is a thick sutural prominence, which gradually 
passes off into a step-like increase of the anterior whorls (well seen in figs. 4 a 
and 4 b), which are short and flat, and without ornament. The type specimen 
(fig. 4 a) did not enable Mr. Witchell to ascertain the internal structure of his 
 Nerinza conica,” but specimens since obtained by myself (fig. 4 >) show that the 
section is practically identical with that of Ptygmatis Cotteswoldizx, from which it 
is distinguished by its more conical figure and by the strap-like arrangement of the 
lower whorls. The forms 4 c and 4 d represent short conical specimens of 
Ptygmatis Cotteswoldix without the strap-like arrangement of the anterior whorls, 
characteristic of the var. conica. Such specimens are very abundant in the Oolite- 
Marl horizon of Longridge, and may possibly be regarded as abraded specimens 
of the var. conica. At all events, they are short conical varieties of Ptyg. Cottes- 
woldiz with very short whorls. 
‘Relations and Distridution—The peculiar internal character serves to dis- 
. ‘ ane ee) ae 
1 This seems to have been the case with other species of Merinwa. See remarks, p. 195. 
