56 CARBONICOLA, ANTHRACOMYA, AND NAIADITES. 
Localities.—Cockshead Coal-roof, Adderley Green. 
Observations. —Although this form is very distinct from the types of U. acuta, 
it is nevertheless connected with it by a well-marked series of intermediate forms, 
and it is impossible to divide them into distinct species. I have therefore 
considered the extreme form as a variety of C. acuta, and have figured a series 
showing the passage of one into the other. All the specimens came from the roof 
of the Cockshead Coal of Adderley Green. I have chosen a series of adult 
specimens of about the same stage of growth in order to make it more easy to 
follow the transition of shape. 
The feature on which Sowerby and M‘Coy relied so much for the diagnosis of 
C. subconstricta is well marked in this variety,—more so, indeed, than in the 
specific type itself. It is probable that the variability in shape has some connection 
with the variableness of the hinge-character in C. acuta ; and it will be noted, too, 
from the figures, that the variety as well as the type-species was subject to erosion 
of the umbones. A similar variation between an acute and a more quadrate form 
obtains in C. aquilina. 
4. Carponicona ovatis (Martin). Plate IV, figs. 183 —22; Plate V, fig. 38. 
Mya ovatus, Martin. Petrefact. Derb., 1809, pl. xxvii, figs. 1, 2; pl. xxviil, fig. 5. 
Non Unio untrormis, Sow. Min. Conch., 1812, p. 84, pl. xxxiii, fig. 4. 
Syn. — acutus, Dumont. Geol. of Liége, 1832, p. 356. 
= — Davreux. Essai sur la constitution géognostique de Liége, 1833, 
pl. v, figs. 4, 8. 
— caRBonarius, Goldfuss. Petrefact. Germ., 1834-40, p. 181, pl. exxxi, 
fig. 19. 
— fELLINARIUS, Goldfuss. Ibid., p. 180, pl. exxxi, fig. 16. 
—  cENTRALIS, Sow. Trans. Geol. Soc., 1840, ser. 2, vol. v, p. 491, pl. xsxix, fig. 13. 
— (no specific name), Rhind. Age of the Earth, 1838, pl. u, fig. Pr. 
Carprnia ovauts, de Koninck. Carb. Foss. Belg., 1842-4, p. 74, pl. u, fig. 2. 
a avRatvA, de Koninck. Ibid., p. 75, pl. x, fig. 3. 
Pacuyopon Ruinpit, Brown. Ann. Mag. Nat. Hist., vol. xii, 1843, pl. xvi, fig. 2. 
Unio Ruinpit, Brown. Foss. Conch., 1849, p. 187, pl. xxiii, fig. 5. 
Non AnrHracosra ovauis, Salter. Geol. Surv. Mem., Iron Ores 8. Wales, pt. 3, 1861, 
p- 228, pl. 11, fig. 22. 
—_ centTRALIS, Hull. Coal-fields Gt. Britain, 1881, p. 38, pl. 11, fig. 4. 
Non — cas Ward. Trans. North-Staff Inst. Min. and Mech. 
Engineers, vol. x, 1890, pl. i, fig. 16. 
Non — SUBNUCLEUS, Amalizky. Paleontographica, vol. xxxix, 1892, p. 156, 
pl. xx, figs. 19, 20 (said to resemble 
Anthracosia ovalis, centralis, and wni- 
formis). 
