ANTHRACOMYA MODIOLARIS. 95 



specimens from Oldham and Longton were somewhat different in appearance. 

 These shells are now re-figured on PI. 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 PI. 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, 



fi g s. 1—11 and 32 ; Plate XVI, figs. 49—53. 



Unio modiolaris, Sow. Trans. Geol. Soc, vol. v, pt. 3, 1S10, pi. xxxix,tig. 10 bis. 

 Modiola cuetata, Brown. Foss. Couch., 1849, pi. lxxii, figs. 19, 20. 



— Kobertsoni, Brown. Ibid., pi. lxxii, figs. 24-, 25. 

 Ukio modiolaris, Brown. Ibid., pi. lxxxviii, tigs*. 5, 6. 



Anthracomta modiolaris, Salter. Mem. Geol. Surv. of Great Britain ; The Iron 



Ores of Great Britain, pt. 3, 1861, p. 230, 

 pi. ii, fig. 13. 

 __ _ Ward. Trans. North .Staff. Inst. Min. and Mech. 



Engin., vol. x, 1890, pi. i, fig. 10. 



— Hind. Quart. Journ. Geol. Soc., vol. xlix, 1893, p. 205, 



pi. x, figs. 2i — 20. 



— dolabrata (pars), Hind. Ibid., pi. ix, figs, i and 5. 



— sp. nov., Hind. Ibid., p. 271, pi. x, tig. 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 



