CONOCARDIUM ALIFORME. 461 



CoNOCAKDiUM MINAX, de Konitick, 1885. Anu. Mus. Roy. Hist. Nat. Belgique, 



vol. xi, p. Ill, pi. xix, figs. 22 — 25. 



— AfiMATUir, de Koninch, 1885. Ibid., p. 110, pi. xix, figs. 19 — 21. 



— ALIFORME, Etheridge, 1888. Brit. Foss., pt. 1, Palaeozoic, p. 281. 



— AEJiATUM, Etheridge, 1888. Ibid., p. 281. 



— MiNAX, Etheridge, 1888. Ibid., p. 281. 



? — ALIFORME, Tornquist, 189(j. Fossilfiihr. Untercarbon. Sudvogesen ; 



Abh. geol. Specialkarte Elsass- 

 Lothringen, vol. v, p. 644 [p. 110], 

 pi. xxiii, fig. 13. 



Specific Characters. — Shell below medium size, trigonal, gibbose in the middle 

 portion, no keel, anterior wing triangular, conical, dilated, but narrowed from 

 above downwards. The anterior end gapes widely and is twisted on itself, 

 separated from the body of the valve by a gradual constriction, in front of which 

 it expands again. The anterior border is short and convex. The superior border 

 descends at first with a convex curve, but becomes concave just anterior to the 

 junction of the main and anterior portion of the valves ; posterior to this it 

 becomes markedly convex, till it passes backwards and upwards, bisecting the 

 posterior surface, terminating in the base of the rostrum. The hinge-line is 

 straight and elongate, continuous posteriorly with the upper border of the rostrum. 



The posterior surface is comparatively large, cordate; as a whole slightly 

 convex, but very gently concave around the base of the rostrum. Posterior 

 surface is placed almost vertically to the long diameter of the shell, and is divided 

 by a well-marked excentric line into two parts, the upper of which is concave and 

 more markedly ribbed than the lower. 



The body of the valve is triangularly swollen, but the lateral surface passes 

 into the posterior surface with a rapid curve, and no ridge or keel. The umbones 

 are small, pointed, incurved, and somewhat flattened on their posterior aspect ; the 

 lunule elongate, broad, and well marked. The rostrum appears to have been 

 long and delicate. 



Interior. — As in G. Herculeum, de Koninck. 



Exterior. — The surface is covered by fine radiating ribs, crossed by almost 

 obsolete concentric lines of growth. The better preserved the shell the finer are 

 the markings ; and if the other layers of the shell be removed, much more 

 marked and fewer, but thicker ribs are seen, the thick ribs being alternate to the 

 ribs of the opposite valve. Shell thick. 



Dimensions. — PI. LIV, fig. 6, measures — 



Antero-posteriorly . . . .20 mm. 



Dorso-ventrally . . . .15 mm. 



From side to side . . . .15 mm. 



Localities. — England : the Carboniferous Limestone of Hill Bolton, near 



