DELPHINULA. 363 



bordering the umbilical excavation being roughly serrated. The umbilical hollow 

 terminates in a true umbilicus of considerable depth. Aperture circular, with an 

 expansion of the inner lip, so as to produce a slight projection towards the 

 columellar extremity. 



Relations and Distribution. — This form occurs rarely in the " Base-bed " at 

 Lincoln, and also at Stoke Lodge. I possess a specimen, considerably larger than 

 the one figured, said to have come from the Inferior Oolite of Rodborough Hill. 



298. Delphinula alta-acanthica, sp. nov. PI. XXX, fig. 9 ; variety, fig. 10. 



Description : 



Height . . . . .8 mm. 



Width . . . . .10 mm. 



Differs from the preceding chiefly in the more gaping suture, in the freedom 

 from bicarination, which is especially marked in the body-whorl ; and, above all, 

 in the great size and length of the spinous processes (hollow) on the single carina 

 situate at the angle of each whorl. 



Relations and Distribution. — It is just possible that this form may represent 

 D. alta, M. and L., under circumstances which permit of its bizarre ornamentation 

 being preserved. 



Excellent specimens are occasionally obtained from the "Base-bed" at 

 Lincoln. Hitherto I have not noticed this particular form elsewhere in the 

 Inferior Oolite. 



Delphinula acanthica, var. depressa, fig. 10. 



Description.— Height 4'3 mm. ; width (without spines) 65 mm. Number of 

 whorls the same as in the more usual form, but all extremely depressed. The 

 penult and body- whorl are flattened out, angular, muricated, and furnished with a 

 keel, which produces wide-apart, upturned spines, whose length keeps increasing 

 anteriorly until a very salient projection is attained. 



This is the most bizarre of all the forms connected with this group of 

 Delphinula. For comparison vide list given supra. It is just possible that 

 Euomphalus coronatus, Sow., may be a micromorph, though, if Sowerby's enlarge- 

 ment is to be relied on, that shell is more likely to be a Straparollus. 



Rare in the " Base-bed " at Lincoln. 



