170 PAPERS, ETC. 



Esq., of Ciifton, to wliom the Museum of the Bristol 

 Philosophical Institution is so mucli indebted. The shell 

 also occurs in the Inferior Oollte of Minchinhampton, 

 Gloucestershire. 



Ckania Ponsortii, Eug. Deslongchamps. 



PL II., figs. 9, 10. 



The shell described under the above specific name was 

 found by M. Deslongchamps in the Great Oolite of St. 

 Aubin. It occurs in the coralline beds of Hampton ClifFs, 

 and with it the Crania antiquior of Jelly is found in great 

 numbers. The outer surface of the latter shell is character- 

 ized by possessing a somewhat rugose or wrinkled surface, 

 and the interior by its well definedmuscular impressions, 

 which always occupy the sanie position in the species, and 

 give pretty unifornily the same pattern to the interior. 

 The interior of C. Ponsortn appears to be undistinguishable 

 from it, the chief dlfFerence being in their outer surfaces. 

 This, in the C. Ponsortü, possesses plications which give it 

 a slightly spinöse aspect. After examining many examples 

 of the C. antiquior, I have observed in some of them a 

 tendency to become more rugose, and to pass gradually 

 into the form representcd by the above shell, and I am 

 therefore dlsposed to consider it only a variety of C. 

 antiquior. 



DISCINA, Lamarck. 



DisciNA DuNDRiExsis, Moore. 



PI. II., fig. 15. 



Shell small, thick, broader than long, flattened, apex 

 smooth, elevated, exterior showing narrow bands of con- 



