CONOCARDIUM. 
23 
species with a more convex posterior margin, and its median and posterior 
regions are completely merged. 
2. CoNOCAEDiuM Marsi, (JEJilevt (?). PI. IX, figs. 12, 12 a. 
1850. CoNOCAEDiTJM CLATHBATUM, de VemeuU. Bull. Soe. Geol. Fr., ser. 2, 
vol. vii, p. 779. 
1877. — ALiFOEME, (Ehlert. Ibid., ser. 3, vol. v, p. 592, 
1882. — CLATHBATUM, Burrois. Eecb. Terr. Anc. Asturies, p. 277. 
1887. — Maesi, (Ehlert. Ann. Sci. Geol., vol. xix, p. 15, pi. i, 
figs. 23—31. 
1889. — — Barrois. Paun. Calc. d'Erbray, p. 160, pi. xi, 
figs. 4 a — d. 
Description. — Sliell very small, equivalve, high, truncated and rostrated in 
front, very conical behind. Umbo direct, incurved, small, situated near the 
anterior side. Anterior margin straight and perpendicular below the rostrum. 
Inferior margin very narrow and oblique. Posterior margin oblique and nearly 
straight. Anterior cordiform slope very large, flat, slightly produced in the centre, 
ornamented by numerous close low rounded ribs, of which the outer are truncated 
by the anterior keel, which extends to the lowest point of the shell. Median region 
very narrow, ornamented with five alternating, close, rounded ribs. Median keel 
indistinct. Posterior slope slightly concave, with about eight narrow, close ribs, 
divided by deep furrows. Posterior region with broader close ribs. Surface 
apparently crossed by irregular growth-lines. 
Size. — Length 7 mm., breadth 8 mm., depth 8 mm. 
Locality. — There is a single specimen in the Torquay Museum, which appa- 
rently came from Lummaton or Barton. 
Remarhs. — Whether this is more than a small variety of G. clathratum is very 
doubtful, but it is distinguished by several particulars. Its great depth gives it 
the appearance of being a full-grown shell. Its shortness, its very narrow 
median region bearing close alternating ribs, its narrow posterior region with 
very broad ribs, and the apparent absence of regular transverse striae, seem on 
the whole to suggest its identity with C. Marsi, (Ehlert, at least as given by 
Barrois. Our specimen is, however, not sufficiently good to permit of certainty 
on the point. 
