cambelajs rocks in south Shropshire. 669 



Ovate, depressed, widest about the middle, two thirds as broad as 

 long, front and sides rounded, beak moderately acuminate, area of 

 ventral valve striated, the striae parallel to the external slope of the 

 valve, pedicel-g'roove divided by a narrow ridge down the middle, 

 visceral surface pitted, exterior surface marked by fine concentric 

 lines of growth. 



Length 5 lines, width 3 J. 



This is a larger shell than L. femir/inea, Salt. ; and its sides are 

 not so parallel. It closely resembles L. Isjpis ; but L. lejpis is wider 

 towards the front, according to Mr. Davidson's figures. 



The Shineton Shales at Shineton, Mary Dingle, Dryton, Cressage, 

 Bull-Hill Cottage, west of Harley, under Cound-Moor quarry, and 

 Pedwardine. Common. 



Gbolella, Billings. 



Obolella SABKI203, Gall. (Plate XXIV. fig. 12.) 



Same reference. 



Small, not exceeding two lines in length, transversely oval, stri- 

 ated concentrically, posterior margin straight ; dorsal valve nearly 

 flat, with a narrow area; ventral valve high, conical, pointed, the 

 beak overhanging the hinder margin, with a distinct false area. 



In the interior, the dorsal valve is furnished with a pair of largo 

 oval muscular scars near the posterior margin, a pair of smaller near 

 the middle, and a large elevated mesial ridge extending nearly three 

 fourths the length of the valve. 



This species bears a close resemblance to 0. scujittalis^ Salt., of 

 the Menevian rocks, but is broader, and has the ventral valve more 

 conical, the median ridge is larger and longer, and the valves are 

 furnished with areas. 



I originally described this form, from incomplete materials, under 

 the name of Metoptoma sabrince, the conical ventral valve closely 

 resembling a patelloid Gasteropod. 



The Shineton Shales at Shineton, Mary Dingle, Dryton, Cressage, 

 one mile west of Cressage, west of Harley, under Cound-Moor 

 quarry. Common. 



Macrocystella, n. gen. 



Calyx subcylindrical, nearly twice as long as its greatest breadth, 

 widest in the middle ; composed of about four rows of "hexagonal 

 plates, two plates occupying the width, those at the ends smaller 

 than the central ones, each compartment of the hexagon being 

 separated from the others by a strong ridge, and containing smaller 

 radiating ridges. 



The calyx is surmounted by a ring of small jointed pinnulee about 

 one fourth the length of the calyx. 



Stem very long, nearly as wide as the base of the calyx at the 

 top, taperiug rapidly at first, continued in a long, slender, slightly 

 tapering column which consists of longer rings than the wider end. 



The shales have not preserved this peculiar form in sufficient per- 



