58 MOLLUSCA FROM THE GREAT OOLITE. 



Nerita HEMisPHiERiCA, Roemer. Plate XI, fig. 16, 16a; 14, 14<z. 



Nerita HEMisPHiEKicA, Roemer. 1836. Nordd. Oolith., p. 156, t. 10, fig. 7. 



N. Testa laevigata, transversa ovali-hemisphcericd; spird parvd, prominuld; aperturd 

 semilunari; labio internet magno, convexo et incrassato. 



Shell smooth, transverse, ovately hemispherical ; spire small ; aperture semilunar ; inner 

 lip large, convex, and incrassated. 



The surface of this species varies considerably ; the younger specimens being smooth, 

 and not unfrequently exhibiting portions of colouring in dark, encircling lines : the older 

 specimens are rendered rugose by numerous large plications of growth. It is not 

 uncommon, being found in all the shelly beds, more especially in the coarse planking. 



Locality. Minchinhampton Common. 



Nerita minuta, Sow. Plate XI, figs. 19, 19«. 



Nerita minuta, Sow. 1824. Min. Con. t. 463, figs. 3, 4. 



— — Desk., 1838. Lam. Anim. sans Vert., 2d Edit., vol. viii, p. 617. 



— — D'Orb. 1850. Prod. Paleont.,.p. 299. 



— pulla, Roemer. 1836. Nordd. Oolith., p. 155, t. 9, fig. 30. 



— ovata, Roemer. Nordd. Oolith., p. 156, t. 10, fig. 6. 



— MAIS, Buvignier. 1843. Mem. Soc. Phil. Verd., t. 5, figs. 18, 19. 



N. Testa parvd laevigata; spird obliqud exsertd et minuta; anfractu, ultimo coloribus 

 lineatis undulatis scepissime picto. 



Shell small, smooth; spire oblique and minute; the last whorl most commonly exhibits 

 undulating-coloured lines, which occasionally coalesce, and are very irregular. 



This little shell is a longer oval figure than both Nerita liemisplicerica (Rom.) and 

 Neritina Coohsoni (Desk) ; the latter little species, with which it nearly agrees in size, is 

 more globose, and has a larger, more prominent, and less oblique spire than N. Pulla. 



N. minuta occurs abundantly in all the shelly beds; its surface is very smooth and shining; 

 the most frequent size is that of duck shot ; the longer diameter not exceeding two lines. 

 Locality. Minchinhampton Common and neighbouring district. 



Sect. 3. Inner lip notched. Neritopsis, Grateloup. 1840. 



N. Testa crassd, neritiformi, ovato-globosd ; spird parvd, obliqud, anfractu ultimo 

 injlato, costis numerosis cincto; aperturd suborbiculari, labro externo incrassato et lavigato, 

 labio interno concavo, sulco lato margine excavato. 



Shell thick, neritiform, ovately-globose ; spire small, oblique ; the last whorl inflated, 

 encircled with numerous costse; aperture suborbicular; the outer lip thickened, but smooth; 

 the inner lip concave, with a wide notch upon its inner border. 



