460 CARBONIFEROUS LAMELLIBRANCHIATA. 



CoNOCAiiDiuM FUSiFouMK, M'Goij, sp., 1844. Plate LII, figs. 1 and 2. 



Pleuroeiitnchtjs fusifoemis, M'Coi/, 1844. Synops. Carb. Foss. Ireland, p. 58, 



pi. ix, fig. 3. 

 CoNOOARDiiJM FUSiFOEME, d'Orhigiiy, 1851. Prodrome Paleontol., p. 131. 



— — Morris, 1854. Cat. Brit. Foss., 2Qd edit., p. 194. 



— — Bit/sbi/, 1878. Tliesaurus Devonico - Carboniferus, 



p. 803. 

 Compare — ueeculeum, de Kon hick, 1S85. Ano. Mu?. Koy. Hist. Nat. Belg., 



vol. xi, p. 103, pi. xviii, figs. 1 — 6. 



— FUSIFOEME, JEtheridge, 1888. Brit. Foss., pt. 1, Palaeozoic, p. 281. 



Specific Characters. — Shell large, triangularly fusiform, obliquely gibbose and 

 truncate, adpressed posteriorly, forming a concave posterior surface, placed 

 obliquely to the general direction of the shell, and compressed in front, forming a 

 broad triangular wing, which is gradually compressed ; separated from the body 

 of the valve by an almost obsolete constriction. The anterior alate portion of the 

 valve is triangular, curved on itself, gradually narrowed at the expense of its 

 lower border, truncate, and gaping; its margin, narrow and curved, passes into 

 the lower border, which is directed downwards and backwards to the postero- 

 inferior angle, becoming concave or sinuous at the point where the anterior alate 

 portion joins the gibbose body of the valve. The hinge-line is straight and long, 

 continuous behind with the upper border of the large rostrum. The umbones are 

 large, gibbose, incurved, not contiguous, flattened behind by the truncation of the 

 valve to form the posterior surface. The posterior surface is cordate and deeply 

 concave, except along the margin of the valves, which, as is usual in the genus, 

 forms a vertical elevated ridge bisecting the posterior surface, and terminating 

 above in the raised base of the rostrum. The outer margin of this surface is 

 formed by a bluntly rounded curved ridge, which projects backwards and extends 

 from the apex of the umbo to the postero-inferior angle. The rostrum is large, 

 long, and tubular; springing from a raised base, continuous above with the hinge- 

 line. The body of the valve is oblique and very gibbose, not well marked off from 

 the anterior wing ; and, viewed from behind, the valves seem much curved on 

 themselves. 



Interior. — The details of the interior differ in no way from the description given 

 of G. Herculeum when defining the genus, p. 451. 



Exterior.— Surface almost smooth, with fine concentric lines of growth, more 

 marked and rougher towards the lower margin. 



Shell very thick, inner and outer layers smooth ; inner layers with well-marked 

 radiating ribs. 



