l(;i CARBONIFEROUS LAMELLIBRANCHIATA. 



LfliOPTBEiA SQUAMOSA, Phillips, sp., I80G. Plate I, figs. 7 — 10. 



GrERviLLiA SQUAMOSA, PMlUps, 1836. Greol. Yorks., pt. ii, p. 212, pi. vi, fig. 9. 



— — Portloclc, 1843. Eep. Geol. Londonderry, p. 438. 



— — Morris, 1843. Cat. Brit. Foss., 1st edit., p. 108. 

 AvicuLA SQUAMOSA, M'Coy, 1844. Sjnops. Carb. Foss. Ireland, p. 84. 



— GiBBOSA, M'C'oy, 1844. Ibid., p. 83, pi. xiii, fig. 25. 

 GrERviLLiA SQUAMOSA, BrotiJi, 1848. Nomencl. Palseont., p. 529. 



— — Brown, 1849. lUustr. Foss. Conch., p. 165, pi. Ixvii, fig. 18. 

 AvicuLA SQUAMOSA, MoTvis, 1854. Cat. Brit. Foss., 2nd edit., p. 162. 



— GiBBOSA, Morris, 1854. Ibid., p. 162. 



— SQUAMOSA, Bicjshy, 1878. Thesaurus Devonico-Carbonifeiiis, p. 287. 



— — Etherichje, 1888. Brit. Foss., pt. i, Palaeozoic, p. 271. 

 — - GIBBOSA, Etheridge, 1888. Ibid., p. 270. 



Specific Characters. — Shell small, obliquely tumid, inequilateral, transversely 

 broadly triangular. The anterior end is short, compressed, the margin rounded ; 

 its anterior superior angle a right angle, separated from the body of the valve 

 by a byssal sulcus. The inferior border is broadly rounded, and ascends posteriorly 

 to meet the posterior margin, which is markedly concave. The hinge-line is long 

 and straight, produced backwards as a short rostrum. The imibones are small, 

 tumid, oblique, pointed, placed far forwards, and not raised. The body of the valve 

 is triangularly swollen, expanded and flattened below and Ijehind ; the dorsal slope 

 is rapidly compressed and hollowed. Posterior wing narrow, elongate, and 

 triangular. 



Interior. — Anterior adductor scar small and round, remote from the anterior 

 border. Posterior adductor scar shallow, larger, rounded, placed in the hollow of 

 the dorsal slope, remote from the margin and hinge-line. Pallial line deep, entire, 

 remote from the margin. Hinge normal. 



Surface. — The external surface is adorned with concentric, equidistant lines, 

 which are separated by well-marked grooves, and follow the contour of the valve, 

 even over the posterior wing. 



Dimensions. — PI. I, fig. 7, from Castleton, measures — 



Antero-posteriorly . . . .28 mm. 



Dorso-ventrally . . . .15 mm. 



From side to side . . . .11 nnn. 



: Localities. — England : the Carboniferous Limestone of Bolland (Phillips) and 



Hill Bolton, Yorkshire ; Castleton and Thorpe Cloud, Derbyshire ; Poolvash, Isle 



of Man ; shales below the Millstone Grits, Congleton Edge, Cheshire. Ireland : 



the Carboniferous Limestone of Manor Hamilton, co. Leitrim. Scotland : the 



