ANTHRACOMYA MODIOLARIS. 95 
specimens from Oldham and Longton were somewhat different in appearance. 
These shells are now re-figured on Pl]. XIII, figs. 10 and 12, but from a further 
study I have come to the conclusion that they more closely resemble A. modiolaris 
in the stronger ridge-like oblique swelling, deeper sinus, and less produced form, 
and I have therefore now referred these two shells to that species. I have been 
able to procure only two other specimens from the original locality, Coalbrookdale, 
but unfortunately both of them are even less perfect than the type. There are, 
however, three in the Museum of the Geological Survey from the same place 
which have the characteristic features. These I have been allowed to examine by 
the courtesy of Mr. E. T. Newton. The shell figured on Pl. XIII, fig. 14, from 
Old Cummock, seems to be intermediate in form between the species under 
discussion and A. modiolaris, to which I have referred it on account of the nearly 
parallel dorsal and ventral margins. A. dolabrata is much more transverse, 
convex, and less expanded than A. Adamsii, with which shell it occurs in the 
Little Mine ironstone of North Staffordshire. 
3. ANTHRACOMYA MoDIOLARIS (Sowerby). Plate XIII, figs. 10 and 12; Plate XIV, 
figs. 1—11 and 32; Plate XVI, figs. 49—53. 
Unto mMopronaris, Sow. Trans. Geol. Soc., vol. v, pt. 3, 1840, pl. xxxix, fig. 10 dis. 
Moptora curtata, Brown. Foss. Conch., 1849, pl. xxi, figs. 19, 20. 
— Rozertsont, Brown. Ibid., pl. Ixxii, figs. 24, 25. 
Unio moproraris, Brown. Ibid., pl. lxxxviii, figs. 5, 6. 
ANTHRACOMYA MODIOLARIS, Salter. Mem. Geol. Surv. of Great Britain ; The Iron 
Ores of Great Britain, pt. 3, 1861, p. 230, 
pl. ui, fig. 13. 
= — Ward. Trans. North Staff. Inst. Min. and Mech. 
Engin., vol. x, 1890, pl. i, fig. 10. 
_ _— Hind. Quart. Journ. Geol. Soc., vol. xlix, 1893, p. 265, 
pl. x, figs. 24—26. 
— DOLABRATA (pars), Hind. Ibid., pl. ix, figs. 4 and 5. 
— sp. nov., Hind. Ibid., p. 271, pl. x, fig. 23. 
Specific Characters.—Shell transversely elongated, trapezoidal, convex. Dorsal 
and ventral margins appear to be sub-lateral in casts, but occasionally the posterior 
part of the shell is produced upwards and compressed. The anterior part of 
the shell is small and bluntly rounded, the upper border being much below the level 
of the umbones. The curvature of the anterior border varies, but the anterior 
superior angle is always the most anterior point of the shell. The inferior 
border is straight for the greater part of its extent, becoming bluntly rounded at 
