NERIN AA. 213 
~ 
also shorter. There is also some difference in details of ornament, but the differ- 
ence of mineralization may partly account for this. It is a good local variety, if 
not entitled to be regarded as a distinct species. 
Rare in the Lincolnshire Limestone at Santon, but more common at Geddineton 
Grange, where the specimens are usually weathered. 4 
Szor1on E.—Folds numerous, simple. 
149, Nertnaa (? Ptygmatis) Gursur, Witchell, 1880. Plate XV, figs. 1 a—c. 
1880. Nerinma Gotset, Witchell. Notes on a Section of Stroud Hill, &., Proc. 
Cottesw. Nat. Field Club, vol. for 1879-80, 
p- 128, pl. iv, fig. 2. 
1887° —- — oa Proe. cit., vol. for 1887, p. 25. 
Bibliography, §c.—In the original diagnosis Mr. Witchell says, “ Columella 
with one fold, outer wall with two folds near the middle of the volution.”? Subse- 
quently, having obtained better specimens, he described the species as possessing 
“two folds on the columella, two on the outer wall, and one on the posterior wall.” 
Description : 
Spiral angle (regular) : : 2) Some 
Height of whorl to width about . F led 
Approximate length . : . 150 mm. 
Shell cylindrical, turrited. Whorls numerous, much excavated, and orna- 
mented with closely-set fine spiral lines (rarely preserved, and probably not 
extending to the more mature whorls). The constriction of the whorls is slightly 
anterior, so that each sweeps up very sharply towards the raised anterior margin. 
Sutural girdles extremely prominent, sutural angle very oblique. 
Aperture oblong, form and length of canal unknown. Section, five folds, with 
two wide but simple folds on the outer walls, two smaller V-shaped folds on the 
columella, and one small V-shaped fold on the posterior wall. 
Relations and Distribution.—This singular and well-marked species appears to 
stand alone in the Inferior Oolite, and to be without near relations in any English 
beds. It is somewhat difficult to say whether it should be regarded as a Nerinza 
or a Piygmatis. The folds on the columellar side are small, so that the section is 
not deeply indented. The existence of species having the internal structure of 
Nerinza cingenda and Nerinea Guisei affords evidence of a bridge, as it were, 
between the triplicate Nerinwe and the more complex internal structure of 
Ptygmatis. 
