SANGUINOLITES HIBERNICUS. 375 



Sanguinolites hibrrnious, sp. nov. Plate XLI, figs. 1 — 4. 



Specific Characters. — Shell below medium size, transversely ovate, obliquely 

 gibbose, very inequilateral. The anterior end is very short, compressed, nar- 

 rowed from above downwards, and elliptically curved, encroached upon above 

 by the lunule. The inferior border is feebly convex, and descends for two thirds 

 of its length, becoming arched upwards posteriorly to meet the posterior margin, 

 with which it forms a bluntly rounded postero-inferior angle. The posterior 

 margin is obliquely truncate from above downwards and backwards ; almost 

 straight or slightly convex. The postero-superior angle is well marked and 

 obtuse. The hinge-line is arched in front, long and straight behind. The 

 umbones are elongate, gibbose, incurved and twisted forwards, contiguous and 

 hardly elevated above the hinge-line, and are situated in the anterior fourth of 

 the valve. Passing obliquely downwards and backwards from the umbo to the 

 postero-inferior angle is a low blunt ridge, which separates the general convexity 

 of the valve from the dorsal slope. Another ridge, erect but curved, passes 

 directly backwards, separating the large escutcheon from the dorsal slope. The 

 general surface of the valve is convex, but the line of greatest convexity is 

 oblique, and there is an obscure flattening of the valve at the junction of the 

 anterior and middle thirds. 



Interior. — The anterior adductor muscle-scar is large, deep, and placed 

 immediately within the antero-superior angle, and is bounded behind by a shallow 

 ridge. The posterior scar is large and shallow, and is placed just below the 

 hinge-line, remote from the posterior margin. The pallial line is entire. The 

 hinge has not been observed. The internal surface of the valves is smooth. 



Exterior. — The surface is ornamented with small, low, concentric ridges, 

 which become almost obsolete when they j^ass over the oblique ridge, and are 

 bent upwards over the dorsal slope to terminate in the hinge-line. The dorsal 

 slope is bisected by an obscure, broad, radiating ridge. Shell thin. 



Dimensions. — PI. XLI, fig. 3, a testiferous example from Ballymark, in the 

 collection of the Geological Survey of Ireland, measures — 



Antero-posteriorly . . . .48 mm. 



Dorso-ventrally . . . .23 mm. 



From side to side . . . .16 mm. 



Localities. — England : the Carboniferous Limestone, Cavedale Quarry, 

 Castleton, Derbyshire. Ireland : the Carboniferous Limestone of Ballymark, 

 Bansha, and Nantinan, co. Limerick. 



