J 54 CARBONIFEROUS LAMELLIBRANCHIATA. 



M'Coy, the other figured by M'Coy as Sanguinolitcs plicatus (op. cit., pi. x, 

 fig. 8 o), but evidently distinct from that species. 



Spathella cylindrica, M'Coy, sp., 1844. Plate XXIII, figs. 1 — 4. 



Ctpricaedia cylindrica, M'Coy, 1844. Synops. Carb. Foss. Ireland, p. 60, 



pi. viii, fig. 23. 

 — socialis, M'Coy, 1844. Ibid., p. 61, pi. viii, fig. 12. 



Specific Characters. — Shell above medium size, transversely elongate, sub- 

 cylindrical, obliquely gibbose, dorsal slope well-developed, hollowed, obliquely 

 constricted by a broad shallow sinus in front of the oblique gibbosity. The anterior 

 end is short and narrow, its margin elliptical. The inferior margin is prolonged, 

 slightly convex, marked in front by a shallow sinus corresponding to the constric- 

 tion of the valve. The posterior end is truncate or bluntly rounded. The hinge- 

 line is straight, shorter than the anterior margin. The postero-superior angle is 

 bluntly rounded. The umbones are small, elongate, slightly raised and placed far 

 forwards, not terminal. 



Interior. — Normal. 



Exterior. — The surface is ornamented with concentric lines and rugas of growth. 



Dimensions. — PI. XXIII, fig. ] , a right valve from Redesdale, measures — ■ 

 An tero -posteriorly . . . .51 mm. 



Dorso-ventrally . . . .19 mm. 



From side to side (estimated) . . . 1G mm. 



Localities. — England ; the Carboniferous Limestone of Poolvash, Isle of Man, 

 and Thorpe Cloud, Derbyshire; the Redesdale Ironstone, Redesdale, Northumber- 

 land. Ireland : the Carboniferous Limestone of Millicent, Kildare ; Araglin Bridge 

 and Kilworth, co. Cork; Learn, co. Fermanagh. 



Observations. — The types of Cypricardia cylindrica, M'Coy, and 0. socialis, 

 M'Coy, are preserved in the Griffith Collection, in the Science and Art Museum, 

 Dublin. That of the latter (PI. XXIII, fig. 3) is a left valve, and the former is a 

 much larger example of a right valve, which has, however, lost its anterior end 

 (PI. XXIII, fig. 2). PI. XXIII, fig. 4, the cast of a right valve from Poolvash, 

 shows the anterior adductor muscle, and the cast of the hinge-plate with cardinal 

 teeth and the obsolete posterior lateral teeth. PI. XXIII, fig. 4 a, the Redesdale 

 specimen, a right valve, is evidently a full-grown example, but it is not quite 

 perfect in front. The Irish localities are given on the authority of Griffith (' Journ. 

 Geol. Soc. Dublin,' vol. ix. p. 36 et seq). 



8. cylindrica is comparatively less transverse and less gibbose than 8. htmida, 



