56 MOLLUSCA FROM THE GREAT OOLITE. 



Sect. 1, Inner lip smooth. 



N. Testa crassd, suhhemisphcericd ; spird parvd obliqud, depressd; anfractibus paucis, 

 carinatis; ap er turd semilunar i ; labio dextro crasso, labio intemo planato, amplo. 



Shell thick, subhemispherical ; spire small, oblique, depressed ; whorls few, carinated ; 

 aperture semilunar ; outer lip thick and smooth; inner lip flat, broad, and smooth, without 

 notch or striae. 



Nerita cancellata. Plate XI, fig. 15, 15a. 



N. Testa crassd, hemisphcericd ; spird parvd, depressd, obtusd; anfractibus (3) carinis 

 tribus cancellatis; carinis obtusis, striis longitudinalibus decussatis, et lineis incequalibus 

 et irregular ibus cinctis ; aperturd transverse oblongd. 



Shell thick, hemispherical; spire small, obtuse, depressed; whorls (3), with three carinas 

 cancellated ; carinas obtuse, decussated with longitudinal striae : the last whorl has also 

 irregular, unequal, encircling lines, which form, with the longitudinal striae, a cancellated 

 surface ; aperture transversely oblong ; inner lip very wide. 



The most frequent aspect is that of a very rugose, depressed Nerite, with large, obtuse 

 carinas and intermediate sulcations ; the distinctly cancellated surface is observable only in 

 the younger examples. The first and second carinas are placed near together ; between 

 these and the basal carina is a large surface, with encircling lines crossing the striae. 

 Portions of coloured surface are sometimes observed upon the carinas and upper portion of 

 the last volution. 



Locality. It is moderately rare at Minchinhampton Common and Bussage. 



Nerita rugosa. Plate XI, fig. 17, 17a. 



R. Testa hemisphcericd; spird parvd, depressd; anfractibus (2ve/3) carinato-striatis ; 

 ultimo anfractu subangulafo, carinis tribus {carina mesa major e), et striis profundis longi- 

 tudinalibus plus minusve crebris; coloribus fuscis sape pictis; labio interno, lato, planato. 



Shell hemispherical ; spire small, depressed ; whorls (2 or 3) carinated and striated ; 

 the last whorl subangulated, having three carinas, of which the middle one is the most 

 prominent and rounded ; the last whorl has, also, longitudinal, deeply-marked striae, more 

 or less closely arranged, and not unfrequently marked with colours, arranged into two 

 broad encircling bands, separated by the mesial carina. 



The longitudinal striae might sometimes, with more propriety, be termed costas ; when 

 the costas are large and distant the carinas are likewise most prominent, and occasionally 

 both conditions may be observed in the growth of the same specimen — the smaller 



