EDMONDIA SUBPLICATA. 315 



Edmondia subplicata, Kirhby, sp., 1880. Plate XXXVIII, figs. 1—5. 



Sanguinolites subplicatus, KirJcby, 1880. Quart. Journ. Geol. Soc, vol. xxxvi, 



p. 586. 

 — — Etheridge, 1888. Brit. Foss., pt. 1, Palaeozoic, 



p. 290. 



Specific Characters. — Shell much produced transversely, almost lanceolate, very 

 feebly gibbose, markedly inequilateral, narrow in the dorso- ventral diameter. The 

 anterior end is compressed and very short comparatively, but long compared to 

 other species of the genus. It is much lower than the umbones, and has a well- 

 marked antero-posterior angle. The border is elliptically curved. The inferior 

 border is very long and almost straight, parallel with the hinge-line, hardly rising 

 at all posteriorly, where it makes a blunted angle with the posterior border. The 

 latter is obliquely truncate from above downwards and backwards, and forms an 

 obtuse angle above with the hinge-line. The hinge-line is straight, much shorter 

 than the inferior border. The umbones are small, compressed, not elevated, and 

 situated in the anterior fifth of the shell. Passing downwards from the umbo to 

 the postero-inferior angle is an ill-defined ridge, above which the valve is 

 flattened and compressed. Elsewhere the valve is only very slightly convex. 

 There is a narrow elongate groove at the upper edge of the valve from the external 

 ligament. 



Interior. — The anterior adductor muscle-scar is deep, circular, bounded behind 

 by a ridge, and placed immediately within the antero-superior angle of the valve. 

 The position of posterior scar is not known. 



The hinge is edentulous. There is a rolled and thickened hinge-plate, bevelled 

 at the expense of its lower border, which projects outwards and downwards. 

 Between this plate and the umbo is a narrow elongate groove, which splits up and 

 becomes irregular in front. Pallial line deep, entire, and remote from the 

 margin. 



Exterior. — The surface is covered with fine concentric lines of growth, which 

 become stronger and subimbricating near the lower margin. Shell very thin. 



Dimensions. — PI. XXXVIII, fig. 1, measures — 



Antero-posteriorly . . . .50 mm. 



Dorso-ventrally . . . .15 mm. 



Elevation of valve . . . .4 mm. 



Localities. — In shale below the limestone east of the Coal Farm, St. Monan's, 

 Fife, and Randerston, Fife; in Limestone No. 5 of Mr. Kirkby (op. supra cit.), 

 Calciferous Sandstone series. 



