PINNA. 99 



Upper Grccnsand (zone of Schlceribachia rout rata) of Blaokdown, Devizes, and 

 Ventnor. 1 



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



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

 P. Bobinaldina in having smaller and more numerous ribs, which are crossed at 

 regular intervals by narrow concentric ridges. 



Pinna tegulata, Etheridge, 1881. 



1881. Pinna tegulata, B. Etheridge, in Penning and Juices-Browne's Geol. Cam- 

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

 fig. 2. 



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

 specimens. The type 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. 



Type. — In the Sedgwick Museum, Cambridge. 



Distribution. — Totternhoe Stone (zone of Holaster subglobosus) of Bnrwell. 



Pinna decussata, Goldfuss, 1837. Plate XIII, figs. 4 a-c, 5, G. Plate XIV, fig. 1. 



1833. Pinna sulcata, S. Woodward. Geol. Norfolk, p. 47, pi. v, fig. 23. 

 1837. — decussata, A. Goldfuss. Petref. Germ., vol. ii, p. 166, pi. exxviii, 



figs. 1, 2. 



— — compressa, Goldfuss. Ibid., p. 167, pi. exxviii, fig. 4. 



? 1840. — pyramidalis, H. B. Geinitz. Char. d. Schicht. u. Petref. des siiuhs. 



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

 — compressa, Geinitz. Ibid, p. 55. 

 1841. — fenestrata, F. A. Bonier. Die Versteiu. d. nord-deutsch. Kreidegeb., 



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



— — decussata, Romer. Ibid., p. 65. 



1846. — pyramidalis, H. B. Geinitz. Gruudr. d. Verstein., p. 451. 



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

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



