458 CARBONIFEROUS LAMELLIBRANCIIIATA. 



of a posterior surface. He says the median part of the shell has three ribs 

 stronger than the others, and that the cordiform surface has four oblique ribs. 

 Although my description differs greatly from his, I think the difference is chiefly 

 in the method of dealing with the peculiar shape of the valve. 



Unfortunately both specimens are incomplete behind, and I have been unable 

 to see the base of the rostrum. De Koninck describes a cordiform surface in this 

 position. 



CoNOOARDinM INFLATUM, M'Coy, sp., 1841. Plate LI, figs. 14 — 17. 



Pleueoehxnchus inflatus, M'Coy, 1844. Synops. Carb. Poss. Ireland, p. 59, 



pi. ix, fig. 2. 

 CoNOCAEDiUM INFLATUM, d'Orhicjiiij, 1851. Prodrome Paleontol., p. 131. 



— AEMATUM (pars), Morris, 1854. Cat. Brit. Poss., 2od edit,, p. 194. 

 Pleueorhtnchus ihflatus, Griffith, 18G0. Journ. Geol. Soc. Dublin, vol. ix, 



p. 91. 

 CoNOCAUDiUM iNFLATUii, c/e Koniiick, 1885. Aim. Mus. Roy. Hist. Nat. Belg., 



vol. xi, p. 106, pi. xix, figs. 11 — 14. 



— — Etheridge, 1888. Brit. Poss., pt. 1, Paleozoic, p. 281. 



? — — Tornquist, 1896. Fossili'iihr. Untercarbon. Sudvogesen ; 



Abli. geol. Specialkarte Elsass-Lotlir., pt. 2, vol. v, 

 p. 116, pi. xviii, fig. 12. 



Specific Characters. — Shell very inequilateral, triangularly couical, swollen, 

 comparatively transverse. The anterior end is alate, produced, triangular, cut 

 away at the expense of its lower margin, gaping, and truncate, its extremity 

 narrow and curved, marked off from the swollen body of the shell by a gentle 

 constriction, oblique in direction. The inferior margin is gently convex, the 

 convexity slightly interrupted at the junction of the anterior wing and the body 

 of the valve, becoming more convex posteriorly, where the border passes upwards 

 to end at the postero-inferior angle. The hinge-line is straight and elongated, 

 continuous behind with the upper margin of the rostrum. 



The umbones are small, pointed, incurved, contiguous, very slightly elevated, 

 swollen, compressed posteriorly. Passing downwards and outwards and back- 

 wards from the umbones to the postero-inferior angle is a curved line, which 

 marks off the body of the valve from the posterior surface. The latter is small, 

 cordate, convex, bisected by an elevated vertical ridge, formed by the everted 

 edges of the opposing valves, continuous above with the raised base of the 

 rostrum. The rostrum has a comparatively large diameter. The posterior 

 surface is oblique, at an angle of about 20° with the hinge-line. The body of the 

 valve is very tumid, and expanded triangularly ; its posterior margin is not 



