ANTHRACOMYA LAEVIS; Var. 123 
and Naiadites (Anthracoptera) ; and, indeed, in perfect examples there is a striking 
resemblance. I rely principally on the position and shape of the umbones, which 
are almost terminal and pointed forwards in Naiadites. 
This shell occurs in very large numbers closely packed and all crushed flat in 
the black bands and ironstones of the Upper Coal-measures of North Staffordshire, 
and here to the exclusion of all other molluscs. 
Professor T. Rupert Jones, F.R.S., who appears to have been the first to figure 
this shell (‘On some Bivalve Entomostraca from the Coal-measures of South 
Wales,” Joc. supra cit.), draws attention to the resemblance in shape between some 
of the Carboniferous Estheriz and the genus Anthracomya. 
15. ANTHRACOMYA L&VIS, var. scotiva, Dawson. Plate XVI, figs. 17—20, 42, 43. 
? Unto rveunosus, Phillips. Murchison’s Sil. Syst., p. 88, 1839. 
? Carpinta Freysrentt,! Geinitz. Die Versteinerungen de Steinkohlenformation in 
Sachsen, pl. xxxv, fig. 7a, a, 1855. 
Natapires tpHvis, Dawson. Acadian Geol., Ist edit., 1860; 2nd edit., p. 204, 
fig. 44, 1868. 
ANTHRACOMYA (NatapDITES) LHvIs, Salter. Quart. Journ. Geol. Soc., vol. xix, 
p- 79, fig. 2, 1863. 
P AnoponTA oBsTIPa, Ludwig. Paleeontographica, Bd. x, p. 22, pl. iii, figs. 2, 2a—f, 
1863. 
Anturacomya Scorica, R. Etheridge, jun. Geol. Mag., dec. 2, vol. iv, p. 244, 
pl. xu, fig. 8, 1877. 
_ Lavis, Hind. Quart. Journ. Geol. Soc., vol. xlix, p. 264, pl. x, 
fig. 31, 1893. 
— _ — Ibid., vol. 1, p. 441, pl. xx, fig. 12, 1894. 
Specific Characters.—Shell obliquely broad-ovate. Dorso-ventral and antero- 
posterior diameters almost equal, hitherto only known as flat and compressed. 
The anterior end is short and pointed, its border is rapidly produced downwards 
and forwards in a curve to join the lower border, which is with the lower part of 
the posterior border almost circular. The posterior end is flattened and pro- 
duced ventrally. The border is rounded below, but almost straight above, and 
obliquely truncate from above downwards. The hinge-line is straight, not quite 
as long as the transverse diameter of the shell; posteriorly the hinge-line forms an 
obtuse angle with the posterior border. The umbones are anterior, not terminal. 
The interior is unknown. 
1 Professor Geinitz writes me that he now considers this shell to be an Estheria. See ‘ Sitz. Isis,’ 
1879, No. 1, p. 10. 
