98 



THE GEOLOGIST. 



Dundry, which have furnished me with so many new forms of Bra- 

 chiopoda. The upper valve only is known. 



Crania Saundersii. Moore. PL ii., figs. 11, 12. 



Shell rounded ; exterior of the valve flattened, or slightly convex ; 

 surface wrinkled; shell-structure smooth. The interior of the valve 

 shows four muscular impressions ; the upper pair being rounded and 

 depressed, the anterior, occupying the middle of the valve, are raised 

 and prominent, ear-shaped, and curved outwardly. 



Obs. — By its exterior it would be difficult to distinguish this shell 

 from the G. antiquior of the Great Oolite of Hampton Cliffs, but the 

 interior of the valves differ. In the C. Saundersii the two pairs of 

 muscular impressions are more widely separated, the lower pair 

 being much stronger, and in shape different from those of the C. an- 

 tiqiMor, and there is also the absence beneath them of a longitudinal 

 ridge usually present in the latter shell. 



It is from the Inferior Oolite of Dundry, near Bristol. I have 

 much pleasure in naming it after ¥m. Saunders, Esq., of Clifton, to 

 whom the Museum of the Bristol Philosophical Institution is so 

 much indebted. The shell also occurs in the Inferior Oolite of Min- 

 chinhampton, Gloucestershire. 



Crania Ponsortii. Eug. Deslongchamps. PI. 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 characterized by possessing a somewhat rugose, or wrinkled 

 surface, and the interior by its well defined muscular impressions, 

 which always occupy the same position in the species, and give pretty 

 uniformly the same pattern to the interior. The interior of C. Pon- 

 sortii appears to be undistinguishable from it, the chief difference 

 being in their outer surfaces. This, in the C. Ponsortii, possesses pli- 

 cations which give it a slightly spinose 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 represented by the above shell, and I am therefore disposed to 

 consider it only a variety of G. antiquior. 



Discina. Lamarck. 

 Pi'tcnin Binnhrcnsis. Moore. PL ii., fis\ 15. 

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

 elevated ; exterior showing narrow bands of concentric lines of growth, 

 which are slightly plicated, giving to the shell a wrinkled surface. 



It is from the Interior Oolite of Dundry, and is the only species 

 known in thai formation. It appears to be rare; for after a 

 Lengthened examination of these beds, I have only succeeded in ob- 

 taining three specimens. 



