ACTINOPTERIA. 131 



crenulated by very numerous sharp radiating and concentric lines, which together 

 cover it with a multitude of minute squares ; surface of front wing similar but 

 slightly coarser ; that of hind wing much coarser, and with the transverse lines 

 dominant. Contour of left valve gently convex. 



Size of Bight Valve. — Length 14 mm., height 14 mm. 



Localities. — There are two specimens from Pilton in the Porter Collection, and 

 one from Landlake in the Museum of Practical Geology. 



Remarks. — The two specimens from Pilton closely agree with Phillips's figure 

 of the opposite (?) valve, and are evidently identical though they do not preserve 

 any signs of the ornament except on the hind wing. The ornament on the 

 Landlake specimen is exactly like that in Phillips's figure, except that it is still 

 more minute. That specimen is rather more oblique and transverse, but it is quite 

 possible that (as it is a mould) it might have been the original of his figure in spite 

 of its appearing to represent the opposite valve. It is flatter than the Pilton 

 specimens. 



Affinities. — Pecten Unteatus, Goldfuss, 1 is very similarly ornamented, but 

 appears to be longer and more direct, and to have more rounded rays and con- 

 siderably larger wings. 



Aviculopecten pelmensis, Freeh, 2 more nearly approaches it in shape, but bears 

 much fewer and coarser radiations. 



6. Genus — Actinopteeia, Hall, 1883. 

 1. Actinopteria eudis, Phillips, sp. Plate XV, fig. 14. 



1841. Avicula rudis, Phillips. Pal. Foss., p. 50, pi. xxii, figs. 85 a, b. 

 ? 1892. Actinopteeia rudis, Whidlorne. Dev. Faun., vol. ii, p. 73, pi. viii, 



figs. 4, 6, 6 a. 



Description. — Left valve very high, slightly oblique, ovoid. Umbo prominent, 

 extending above the hinge-line, situate anteriorly. Hinge-line short. Hind wing 

 short, triangular, very broad, and clearly defined. Posterior margin forming a 

 slightly obtuse angle with the hinge-margin, straight on the wing, and convex 

 below it. Contour of back convex. Surface with numerous fine, sharp, distant 

 rays, and a few indistinct undulations of growth. "Lower valve : general figure 

 elongate, with a square, short hinge-line and prominent beak near the anterior 

 end; surface covered with flexuous and irregular lines of growth" (Phillips). 

 Size. — A left valve measures about 15 mm. high. 



1 1834-40, Goldfuss, ' Petref. Germ.,' vol. ii, p. 78, pi. cxiv, fig. 9 ; and 1891, Freeh, ' Abhandl. 

 Geol. Specialk. Preuss.,' Band ix, pt. 3, p. 17, pi. ii, figs. 3—5. 



2 1891, Freeh, 'Abhandl. Geol. Specialk. Preuss.,' Band ix, pt. 3, p. 15, pi. i, figs. 7—7 I. 



