464 CARBONIFEROUS LAMELLIBRANCHIATA. 



CoKOCAEDiuM KoKiNCKi, Baihj, sp., 1871. Plate LIV, figs. 11 — 13. 



PiEUi OEnTKCHrs KoKiiccKi, Baily, 1871. Journ. E. Geol. Soc. Irtland, vol. iii, 



p. 25, pi. iv, fig. 1. 

 CoNOCAEDitM KoNiNCKi, Bigshy, 1878. Thesaurus Devonico-Carboniferus, p. 303. 



— — de Koninck, 1885. Ann. Mus. Roy. Hist. Nat. Belg., 



vol. xi, p. 105, pi. xix, figs. 1 — 4. 



— — Etheridge, 1888. Brit. Foss., pt. 1, Palseozoic, p. 281. 



Siiecific Characters. — Shell above medium size, very inequilateral. The an- 

 terior portion triangular and compressed, alate; the body very gibbose, obliquely 

 and triangularly swollen, truncate, and adpressed posteriorly to form a cordate 

 posterior surface. 



The anterior end is curved on itself from above downwards, and is prolonged 

 in the form of a triangular wing, marked off from the convex body of the shell by 

 a rapid, oblique, broad constriction. The anterior extremity is much narrowed 

 at the expense of its lower border, truncate and gaping ; the antero-superior 

 angle forms a rounded right angle. From this point the border descends, and 

 curves downwards and backwards, until it approaches the gibbose body of the 

 valve, when the inferior border curves so rapidly downwards that it becomes con- 

 cave till it passes into the inferior border of the main mass of the shell, which, 

 curving slightly upwards to join the elevated edge of the valve at the postero- 

 inferior angle, becomes markedly convex. The upper margin is straight and pro- 

 longed, continuous posteriorly with the upper margin of the rostrum, which is 

 produced slightly upwards and backwards, making a very large angle with the 

 hinge-line. 



The posterior surface is large, cordate, oblique to the main mass of the shell ; 

 its outer portion is convex, the middle excentrically concave, but towards the 

 margin of the valve, which is in contact with its opponent, it becomes raised into 

 a ridge, which passes from the postero-inferior angle to the base of the rostrum. 

 The rostrum is large, long, and tubulai', rising gradually from the upper part of 

 both valves of the shell. 



The umbones are large, gibbose, incurved, and twisted slightly backwards; 

 somewhat elevated above the hinge-line, cut away posteriorly, and flattened by the 

 rapid compression of the valve to form the posterior surface. 



Passing obliquely downwards and backwards from the umbo to the postero- 

 inferior angle is a rounded ridge, which separates the lateral surface from the 

 posterior surface, and reaches the inferior border at the postero-inferior angle. 



Interior. — The inner surface of the shell is smooth, and, as far as details have 

 been obtained, the muscle-scars, hinge-plate, etc., agree with that of G. Herculeum 

 described above. 



