138 CARBONICOLA, ANTHRACOMYA, AND NAIADITES. 
3. NaraprTes carinavTa, Sowerby, 1836-40. Plate XVIII, figs. 1—16. 
Moprona cartnata, Sowerby. Trans. Geol. Soc., ser. 2, vol. v, pt. 3, pl. xxxix, 
fig. 15, 1836-40. 
No name. R&R. Garner. Nat. Hist. of the County of Stafford, pl. £, fig. 19. 
Moptota cartnata, Brown. Foss. Conch., p. 175, pl. Ixi ***, figs. 19, 20, 1849. 
Mytitus Omartustana, de Ryckholt. Mélanges Paléontologiques, p. 144, pl. viii, 
figs. 22, 23, 1850. 
— Mania (pivisus), de Ryckholt. Ibid., p. 142, pl. vii, figs. 15, 16. 
Dretssenta FrLpMant (pars), Ludwig. Palaeontographica, Bd. vin, p. 188, pl. lxxi, 
figs. 3, 4, 1859-60. 
_— DILATATA (pars), Ludwig. Ibid., p. 189, pl. lxxi, figs. 5 and 6. 
Myauryna cartnata, Salter. Geol. Surv. Mem., ‘Iron Ores of South Wales,” 
p- 228, pl. ii, fig. 15, 1861. 
AnTHRacoMya carrnata, Hull. Coalfields of Great Britain, 4th edit., facing 
p. 38, fig. 3, 1873 and 1881. 
Myantna CARINATA, Barrois. Recherches sur les terrains anciens des Asturies et 
de la Gallice, p. 336, pl. xvi, figs. 12 a, 6, 1882. 
ANTHRACOPTERA CARINATA, Ward. Trans. North Staff. Inst. Min. and Mech. 
Engin., vol. x, p. 129, pl. i, fig. 9, 1890. 
= — Hind. Quart. Journ. Geol. Soc., vol. xlix, p. 253, 
pl. vii, figs. 2, 2a, 10, 10a, 11, 12, 12 a, 1898. 
— TUMIDA (pars), Hind. Ibid., pl. vii, figs. 13, 13a, 14. 
Specific Characters.—Shell produced obliquely downwards, rhomboidal, and 
gibbose. The anterior lobe is comparatively larger than in other species. The 
anterior and posterior margins are almost parallel, the anterior being straight and — 
slightly notched about its centre for the byssus, the posterior for the most part 
straight, but slightly convex below at the posterior inferior angle, and may be 
either straight or convex above, according as the angle formed by the junction of 
the superior and posterior borders is a right angle or greater thana right angle. 
The inferior margin is short and rounded, almost semicircular. The hinge- 
line is straight, about as long as any diameter of the shell parallel to it. The 
umbones are anterior, not quite terminal. They at first he parallel to the hinge- 
line, but then become twisted outwards and are continuous with a sharp ridge 
which crowns a broad oblique gibbosity very much more pronounced in the left 
valve. This swelling and ridge pass downwards and backwards and become lost 
on the surface of the shell near the posterior inferior angle, the line of the 
ridge forming with the hinge-line an angle of 45° in most cases. The anterior 
part of the shell forms a small projecting lobe, and is swollen above, but becomes 
compressed obliquely parallel to and in front of the ridge. The posterior part of 
the shell is much compressed, especially above. 
