132 CARBONIFEROUS LAMELLIBRANCHIATA. 



marked, subimbricating, concentric lamellse of growth are to be seen, crossed by 

 fine radiating stria?, better marked anteriorly. 



Dimensions. — PL XXII, fig. 16, the type of M'Coy's Gyprieanlia oblonga, 

 measures — 



Antero-posteriorly . . . .38 mm. 



Dorso-ventrally . . . .12 mm. 



From side to side (estimated from single valve) . 20 mm. 



Localities. — England : the Carboniferous Limestone of Park Hill, Thorpe Cloud, 

 and Castleton, Derbyshire. Ireland : Araglin Bridge, co. Cork. 



Observations. — This species is easily distinguished by its large comparative 

 transverse diameter. I have obtained five specimens from the localities mentioned 

 above, on what I believe to be the same horizon, viz., the upper beds of the 

 Carboniferous Limestone series of the Midlands. De Koninck did not recognise 

 that M'Coy had described his shell under the name Oypricardia oblonga. M'Coy's 

 type (PI. XXII, fig. 1G) is preserved in the Griffith Collection of the Science and 

 Art Museum, Dublin. It is a cast of the interior of the left valve, and it is strange 

 that M'Coy did not recognise this fact. He describes the surface as " smooth, with 

 a few obscure undulations at the posterior end." The radiating ribs described by 

 de Koninck are well marked only in two of my specimens, both right valves. 

 They become finer and closer in character from before backwards. 



Modiola Wrightii, sp. liov. Plate XXII. , figs. 10 — 12. 



Specific Characters. — Shell below medium size, triangularly ovate, equivalve, 

 oblique. The anterior end well developed, narrow, its border rounded. The 

 inferior border is almost straight and descends rapidly downwards and backwards. 

 The posterior border is obliquely truncate, straight for the upper two-thirds, 

 bluntly rounded below where it passes into the lower border. The hinge-line is 

 straight, of moderate length, meeting the posterior margin at a well-marked obtuse 

 angle. The umbones are small, twisted forwards, pointed and only very slightly 

 elevated above the hinge-line, placed a little in front of the centre of the hinge-line. 

 Passing obliquely downwards and backwards from the umbo is an angular ridge 

 which gradually becomes obsolete as it nears the postero-inf erior angle. The valve 

 is compressed and flattened on each side of this ridge. No lunule or escutcheon. 



Interior. — Unknown. 



Exterior. — The surface is ornamented by numerous subimbricating, flattened 

 lamellae, which are themselves covered by close-set but somewhat irregular 

 concentric lines of growth. 



