30 MOLLUSCA FROM THE CRAG. 



This is quite distinct from any of the varieties of P. tigrinus, the larger or more 

 rounded form of the rays, as well as less inequality in the auricles, will distinguish 

 it; and in all the varieties of that species, strongly marked divaricating striae, or 

 curved lines radiating from the umbo, may easily be observed, but I have been unable 

 to detect such markings upon my specimens of this species, although individuals of 

 tigrinus, much less in size, exhibit them distinctly ; and it seems also to be specifically 

 different from P. Dumasii, in which the rays are larger, fewer, and more prominent, 

 and the auricles of our shell are comparatively larger than those in that species. In 

 the recent state, this is, probably, a deep water species, as Payraudeau speaks of his 

 specimens having been obtained by means of the dredge. 



6. Pecten danicus, Chemnitz. Tab. IV, fig. 2. 



Pecten Danicus. Chem. Conch. Cab., t. xi, p. 265, pi. 207, fig. 2043, 1795. 



— G. Sow. Thesaur. Conch., vol. i, p. 61, pi. 12, figs. 16 & 187. 



— — Fori, and Hani. Hist. Brit. Moll., vol. ii, p. 288, pi. 52, figs. 1, 2, 7— 10. 



— glabris. Brown. 111. Brit. Conch., pi. 32, figs. 3, 4, 1827. 



— Dumasii. Payr. Cat. Moll, de l'lle de Corsi., p. 75 pi. 2, figs. 6, 7, 1826. 



— — Desk. Append. Lyell's Princ, vol. iii, p. 15, 1833. 



— — Forbes. Rept. iEgean Invert., p. 183, 1843. 



— — Jeffreys. Ann. Nat. Hist., vol. xix, p. 313. 



— aspersus. Desk. 2d ed. Lam., t. vii, p. 136, 1836. 



— Phil. En. Moll. Sic. vol. i, p. 82. 1836; and vol. ii, p. 57, 1844. 



— Jamesoni. Smith. Mem. Wern. Soc, vol. viii, p. 58, pi. 2, fig. 1, 1838. 



— — Brown. Illust. Conch. Gr. Brit., 2d edit, p. 73, pi. 25, fig. 7. 



— septemradiatus. Loven. Ind. Moll. Scand., p. 31, 1846. 



— triradiatus. Mull. Zool. Dan., vol. ii, p. 25, pi. 60, figs. 1, 2, (fide Loven and Desh.) 

 Ostrea hybrida. Gmel. Syst. Nat., p. 3318, 1788 (fide Loven). 



— — W. Wood. Ind. Test., p. 48, pi. 10, fig. 10, 1825. 



— triradiata. Turt. ed. Linn., vol. iv, p. 268, 1806. 



— W. Wood. Ind. Test., p. 50, pi. 10, fig. 39, 1825. 



SEPTEMRADIATA. Id. - - p. 268, 1806. 



— inflexa. Poli. Test. Sicil., vol. i, p. 160, t. 28, figs. 4, 5. 



— clavata. Id. - - p. 161, t. 28, fig. 17. 



Pecten Pseud-Amusidm. Desh. Exped. Scient. de Morea, p. 231, pi. 2, figs. 9—11, 1833. 

 Ency. Meth., pi. 212, fig. 6. 



Spec. Char. Testa subrotundatd, cequilaterali, radiis 5 — 6 rotundatis inaqualibus, 

 striatis ; auriculis incequalibus . 



Shell subcircular, equilateral, thin, with rounded or convex rays varying in number 

 from 5 to 6 striated ; auricles unequal. 



Diameter, 1 inch. 



Locality. Clyde Beds. Recent, iEgean, and Scandinavia. 



Although this species, in the recent state, has been obtained in the iEgean, as 

 w ell as in the Mediterranean Sea, and is quoted also by Philippi as an abundant fossil 



