PINNA. 99 



Upper Greeiisand (zone of Schla;nhachia rodrata) of Blackdown, Devizes, and 

 Ventnor.^ 



Pinna, sp. Plate XIII, figs. 2, 3. 



Some specimens of Pinna found in the Gault of Folkestone differ from 

 P. liohhidhUna in having smaller and more numerous ribs, wbicli arc crossed at 

 regular intervals by narrow concentric ridges. 



Pinna tegdlata, Etherichje, 1881. 



1881. Pinna tegulata, R. Etheridge, ia Penning and JuJces-Browne's Geol. Cam- 

 bridge (Mem. Geol. Survey), p. 142, pi. i, 

 fig. 2. 



Bemarlcs. — This species is known only by the type and a few fragmentary 

 specimens. The tj^pe shows the interior of a right valve. The ornamentation 

 appears to be similar to the form from the Gault described above. On the dorsal 

 half of the valve there are about 18 narrow ribs, which are crossed at regular 

 intervals by concentric ridges, giving rise to a fimbriated appearance. About 8 

 similar ribs are found on the dorsal part of the ventral half of the valve, below 

 which are strongly curved growth-ridges. 



Typo. — In the Sedgwick Museum, Cambridge. 



Distribution. — Totternhoe Stone (zone of Hulastcv suhgluhusua) of Eurwell. 



Pinna decussata, GohJfnss, 18o7. Plate XIII, figs, -ia-c, 5, G. Plate XIV, fig. 1. 



1833. Pinna sulcata, <S'. WoodirariL Geol. Norfolk, p. 4:7, pi. v, fij,'. 23. 



1837. — DECUSSATA, A. Goldfusn. Petref. Germ., vol. ii, p. 1(JG, lA. cxsviii, 



fi!,'S. 1, 2. 



— — coMPRESSA, Goldfuss. Ibid., p. 1(37, pi. cxxviii, fig. 4. 



"r 1840. — PYRAMiDALis, U. B. GeiiiUz. Cbar. d. Scbiebt. u. Petref. des sachs. 



Kreidegeb., pt. 2, p. 55, pi. x, fig. 1, 



— — coMPEESSA, Geinitz. Ibid, p. 55. 



1841. — FENESTRATA, F. A. Buiner. Die Vcrsteiu. d. uord-deutsch. Kreidegeb., 



p. 65, pi. viii, fig. 22. 



— — DECUSSATA, Bonier. ILiiJ., p. 65. 



1846. — PYRAMIDALIS, H. B. GeiuHz. Gruudr. d. Versleiu., p. 451. 



' I have not seen any specimen of Pinna ? crassa, Fittou, * Trans. Geol. Soc.,' ser. 2, vol. iv (1836). 

 p. 130 ; Morris, ' Cat. Brit. Foss.,' p. 180. 



