130 DEVONIAN FAUNA. 



Pecten subradiatus, F. A. Romer, 1 from the Culm, which is very similar in 

 shape, is described as having numerous finer lines between the major rays. 



Avicula Posidonis, F. A. Romer, 2 is more transverse and squarish, with 

 comparatively larger wings and finer rays, but in other respects is similar. If his 

 specimen had been subject to considerable transverse contortion it might perhaps 

 have approximated our species ; but Romer seems to imply that its figure 

 represents its true shape, while specimens show that Sowerby's figure is not much 

 contorted. 



Pecten pohjtrichus, Phillips, 3 as given by Romer 4 and by Freeh, 5 differs in 

 having smaller wings and umbo, broader sides, and a decidedly more rounded 

 form, as well as a few of the rays somewhat greater than the rest. Phillips's own 

 species is still farther removed ; it differs from the shell which these German 

 authors have identified with it by the very much greater inequality of its major 

 and minor ribs, and is akin to, if not identical with, the species named Avicula 

 Ibergensis by F. A. Romer. 6 



P. Helmerseni, Semenow et Moller, 7 is similar, but has only transverse 

 striations on its wings. 



Grenipecten Winchelli, Meek, 8 may be compared with it, though probably not 

 congeneric. 



Pecten oceani, Goldfuss, 9 has much coarser ribs. 



3. Aviculopecten granulosus, Phillips, sp. Plate XIII, fig. 15. 



1841. Pecten gbanulosus, Phillips. Pal. Foss., p. 46, pi. xxi, figs. 75 a, b. 



Description. — Shell small, obliquely ovate, as broad as long. Umbo small, 

 oblique, acute, situated nearly at the anterior third of the length. Hinge- 

 margin straight, about half the length of the shell. Wings small, tri- 

 angular, broad, flat, very sharply defined, and with gently sigmoid margins ; 

 the hind wing being rather larger and longer than the front. Other margins oval, 

 the greatest convexity being in the postero-inferior region. Surface microscopically 



1 1852, F. A. Romer, ' Beitr. Harzgeb.,' pt. 2, p. 91, pi. xiii, fig. 19. 



2 1855, F. A. Eomer, ibid., pt. 3, p. 11, pi. iii, fig. 4. 



3 1841, Phillips, ' Pal. Foss.,' p. 46, pi. xxi, fig. 76. 



4 1860, F. A. Eomer, ' Beitr. Harzgeb.,' pt, 4, p. 161, pi. xxv, fig. 5. 



5 1891, Freeh, 'Abhandl. Geol. Specialk. Preuss.,' Band ix, pt. 3, p. 16, pi. i, figs. 9—9 5. 



6 1855, F. A. Eomer, « Beitr. Harzgeb.,' pt. 3, p. 35, pi. vii, fig. 3. 



7 1863, Semenow and Moller, ' Melange Phys. et Cbim.,' vol. v, p. 679, pi. iv, figs. 14 a, b. 



8 1875, Meek, 'Pal. Ohio,' vol. ii, p. 296, pi. xv, figs. 50, 56; and 1884, Hall, 'Pal. N. T.,' 

 vol. v, pt. 1, p. 89, pi. ix, fig. 1, 2, 4, 25—30. 



9 1834-40, Goldfuss, ' Petref. Germ.,' vol. ii, p. 42, pi. lxxxviii, fig. 10. 





