206 GASTEROPODA OF THE INFERIOR OOLITE. 
these may be doubtful in some instances. It is evidently closely related to some 
of the species next to be described. 
My own specimens of N. Hudesii are from Weldon, where it is by no means 
abundant. 
139, Nertnma WELponIs, sp. nov. Plate XIV, figs. 3a, 3b, 4, and ? 5 (apical 
conditions). 
Description : 
Spiral angle (regular) ; : . 12°—16°. 
Height of whorl to width, average . Aah! Ei 
Approximate length ; : . 45 mm. 
Shell cylindro-conical, turrited. Whorls from fourteen to eighteen, mode- 
rately concave, the extreme depression being slightly anterior. The sutural 
belt is tolerably prominent, but in the narrower varieties (3 a) the posterior 
margin of each whorl constitutes the most marked prominence. Fine spiral 
lines may be traced on the apical whorls, two very slightly granulated ones 
showing a little above the others. These ornaments probably change with the 
age of the whorls, but the available specimens are for the most part much 
defaced. Columella ? hollow, with closed umbilicus. 
The aperture is subquadrate. Section triplicate; one deep fold in the centre 
of the outer walls, the fold on the lower part of the columella very small, the 
fold in the posterior wall (upper columellar fold) deeply impressed. 
Relations and Distribution.—Differs from N. Hudesii in the smaller spiral angle 
and less excavated whorl, although it undoubtedly approaches closely to the 
Lincolnshire Limestone variety of N. Hudesii, which may be regarded as forming 
the connecting link between N. Weldonis and the true Bathonian form. It also 
has affinities with some varieties of Nerinzxa oolitica,' and probably with certain 
Bathonian Nerinzas described and figured by Cossmann from beds in the north 
and east of France. 
Forms such as fig. 3a and fig. 4 are abundant at Weldon, which is in the 
upper part of the Lincolnshire Limestone. These beds show some affinity to 
the Great Oolite, but less so than those of Great Ponton. Fig. 5 is believed to 
represent the apical conditions. 
1 There can be little doubt that these named forms are modifications, due to time and place, of 
other named forms, and that they pass into each other. 
