198 GASTEROPODA OF THE INFERIOR OOLITE. 



A 3 (fig. 17). Spiral angle 16°, height of whorl to width 1 : 1'65, length of 

 figured specimen 16 mm. Shell conical-elongate, scarcely turrited; whorls short 

 and smooth ; sutures rather open. Body- whorl slightly constricted posteriorly ; 

 section uniplicate. 



A 4 (fig. 18). Spiral angle 16°, height of whorl to width 1 : 1"5, length of 

 figured specimen (restored) 20 mm. Shell conical-elongate, strongly turrited. 

 The whorls are smooth and marked posteriorly by a bevilled margin of consider- 

 able breadth. Body-whorl salient, and constricted in the middle. Section 

 uniplicate. 



The four specimens figured and partially described above clearly belong to at 

 least three very distinct species of Nerinella. Like so many of the Weldon 

 Nerinseas, there is an appearance as though the columella had been partially 

 hollow, but in all cases the umbilicus is closed. The appearance of excessive 

 smoothness is probably misleading. 



Section B (Biplicat^). 



127, 128. Species of biplicate Nerinella found in the Lincolnshire Limestone 



at Weldon. Plate XIII, figs. 1 and 2. 



B 1 (fig. 1). Spiral angle 13°, height of whorl to width 1 : 1-6, length of 

 fragment 16 mm. Shell elongate, strongly turrited ; whorls encircled by a 

 wide posterior rim (slightly bevilled), otherwise smooth and constricted in the 

 anterior third. Section biplicate ; ^. e. a simple central fold on the outer wall, and 

 a very slight fold on the columella. 



B 2 (fig. 2). Spiral angle 17°, height of whorl to width 1 : I'S, length of 

 fragment figured 22 mm. Shell conical-elongate, scarcely turrited. Whorls 

 nearly flat, without visible ornament, and very slightly raised at each extremity, 

 where they meet the sutures. Section biplicate and similar to the preceding, 

 except that the fold of the lower part of the columella is even less developed. 



Nerinellx with two folds have not, as far as I know, been hitherto figured 

 from the British Jurassic rocks. The group is more characteristic of Bathonian 

 beds, whence fine specimens of Nerinella Bathonica, Rig. and Sauv., have lately 

 been obtained in the Cotteswolds. 



