GASTEROPODA. 59 



NERITOPSIS STRIATA. Plate XI, figs. 13, 13a. 



N. Testa ovatd; spird elatd; anfractibus tribus, convexis; anfractu ultimo costis nume- 

 rosissimis crebris cincto, costis subundulatis ; aperturd ampld, ovatd. 



Shell ovate ; spire elevated ; whorls (3) convex ; the last whorl encircled with numerous 

 and closely-arranged costae, which slightly undulate ; aperture large and ovate. 



The costae are narrow, but slightly elevated, the interstitial spaces being so narrow as 

 to appear like striae ; hence, in badly-preserved specimens, the costae can scarcely be dis- 

 cerned ; the spire is small, moderately prominent, and has its surface distinctly sculptured 

 in good examples : the specimen figured is rather beneath the average size. 



Locality. Minchinhampton Common, where it occurs somewhat rarely in the soft, 

 shelly oolite which underlies the planking. 



NERITOPSIS SULCOSA. Plate XI, fig. 12. 



? NEEITA SULCOSA, Archiac. 1843. Mcm. Soc. Gol. Fr., vol. v, tab. 28, fig. 8. (Non Brocchi.) 



N. Testa ovatd; spird parvd; anfractibus tribus vel quaternis, convexis, sulco lato 

 spirali superne instructis ; anfractu ultimo permagno, cingulis ineequalibus, numerosis, 

 et magnis ornato. 



Shell ovate ; spire small ; whorls (3 or 4) convex, with a wide, encircling sulcus upon 

 their upper portions; the last whorl very large, with numerous, unequal, and large 

 encircling bands. 



The encircling ribs extend only upon the last volution, their inequality and large size 

 give to the surface a rugose aspect ; the sulcus upon the upper part of the last whorl is 

 without costae ; the specimen figured is of the largest dimensions. 



Locality. Minchinhampton Common, where it occurs somewhat rarely in the shelly 

 beds of coarse planking. 



PILEOLUS, G.B. Sowerby, 1823. 



" Shell conical, with a subcentral upright vertex ; base concave, with a thin margin 

 and tumid centre ; aperture small, within the margin of the base, sublateral, semilunar, its 

 outer Up prominent, the inner one crenulated ; spire internal, very short." Sowerby. 



