CRENIPECTEN. 139 



IV. Family — Pectinidjs, Fleming, 1828. 



1. Genus — Crenipecten, Hall, 1883. 



I have placed the following shell under the present genus because I think I 

 can see faint indications of a crenulated hinge-line, which, however, the roughness 

 of the matrix renders very doubtful. 



1. Crenipecten? auritus, n. sp. Plate XV, fig. 7 ? and Plate XVI, figs. 15, 16. 



Description. — Right valve small, flat, short, direct. Umbo small, central, 

 direct, acute, flattened, proximate, and not extending above hinge-line. Hinge- 

 line very nearly equal to the greatest length, apparently pitted or dentated. 

 Anterior wing very large, broad, an almost right-angled isosceles triangle in shape, 

 bearing indications of rays, and separated from the body by a deep hollow groove 

 or sinus. Anterior and posterior margins almost straight and direct superiorly, 

 convex inferiorly. Inferior margin short and convex. Contour very flat. 

 Surface of back bearing ten or twenty very low, rounded rays. 



Left valve rather more convex. Umbo small, extending slightly above the 

 hinge-line. Anterior wing short, triangular, very broad, bearing a few rays, 

 having a convex margin, and separated from the body by a deep straight groove. 

 Surface (except the wing) covered by low, rounded, distant, irregular ribs, which 

 do uot all reach the umbo, and are separated by wider, shallow, concave inter- 

 spaces. 



Size. — Length 8 mm., height 10 mm. 



Localities. — In the Barnstaple Athenaaum are two specimens of the right valve 

 from Top Orchard, and one of the left valve from Bradiford, and in the Porter 

 Collection one left valve from Pilton, and another, which is doubtful, from Smoking 

 House Lane. 



Remarks. — This shell appears to be distinct, and probably rather far removed 

 from the other species occurring in these beds. Owing, however, to the very poor 

 state of preservation of the specimens its description is very difficult ; and it has 

 proved impossible to figure it in a satisfactory manner, the critical points being 

 much obscured by the matrix, or by fracture of the shell. 



The specimen from Bradiford, though indistinct, appears undoubtedly to be a 

 left valve; and therefore it appears that we can identify the full shell, and may 

 regard it as distinct from any other species which is known by only one of the 

 valves. 



