CARBONICOLA SUBCONSTRICTA. 59 
Dimensions : 
Antero-posteriorly : : ; . 48 mm. 
Dorso-ventrally : : : . 27 mm. 
Laterally s : 15 mm. 
Locality.—Coal-shale, Polmont, near Falkirk. Springhill Colliery, near Kil- 
marnock. Kirkwood Upper Coal-measures, Ell-coal, Kilwinning, Ayrshire. 
Observations.—I have met with this form only in Scotch localities. Unfortu- 
nately I have not seen any testiferous examples, and am quite unable to state 
anything as to the external characters of the shell. The form was originally 
figured by Dr. Rhind in his little work ‘ The Age of the Earth,’ and was named 
Polmontensis by Captain Brown from the locality whence it was first obtained, and 
he refigured the shell, giving a typical figure of the umbones and upper surface of 
the shell as shown in a cast. In casts the peculiar long, narrow, widely-separated 
umbones are quite characteristic. 
I figure specimens from the several Scotch localities, which are all in the 
Upper Coal-measures. The figures show a slight variation in shape. 
The shell appears to have some resemblance to C. acuta, but it is flatter, and 
differs from that species in the peculiarity of the umbones. 
6. CARBONICOLA suBCONSTRIOTA (Sowerby). Plate VI, fig. 44; Plate VII, figs. 5—15. 
Unto susconsrricrus, Sow. Min. Conch., vol. i, 1812, p. 83, pl. xxxiii, figs. 1—3. 
_ _— Defrance. Dict. Sci. Nat., 1824, vol. xxxiii, p. 294. 
— — Dumont. Constitution géologique Liege, 1832, p. 356. 
— Goldfuss. Petrefact. Germaniz, 1834—40, pl. exxxi, fig. 18. 
CarDINIA suBCONSTRICTA, Agassiz. Trad. de Sowerby’s Min. Conch. (1842), p. 58, 
pl. xxiii, figs. 1—3. 
_— — de Koninck. Carb. Foss. de Belgique, 1842-4, p. 73, 
pl. I, fig. 9. 
PACHYODON SUBTRIANGULARIS, Brown. Ann. and Mag. Nat. Hist., 1843, vol. xii, 
p. 393, pl. xvi, fig. 6. 
— Smirxi, Brown. Ibid., p. 398, pl. xvi, figs. 7, 8. 
— Emsxetont, Brown. Ibid., p. 393, pl. xvi, fig. 9. 
— Hey, Brown. Ibid., p. 393, pl. xvi, fig. 10. 
UNIO sUBTRIANGULARIS, Brown. Fossil Conch., 1849, p. 178, pl. lxxiii, fig. 12. 
— Smirnu, Brown. Ibid., p. 178, pl. lxxiii, figs. 10, 11. 
— Enmezeront, Brown. Ibid., p. 178, pl. lxxiii, fig. 6. 
— Hoey, Brown. ibid., p. 178, pl. lxxiii, fig. 1. 
CaRBonicoLa suBconstricra, M‘Coy. Brit. Paleozoic Foss., 1855, p. 515. 
AntHracosia Smiruit, Aing. Ann. Mag. Nat. Hist.,ser. 2, vol. xvii, 1856, pl. iv, 
fig. 6. 
Specific Description.—Shell ovate ; anterior end rounded and short. Posterior 
end obliquely truncate from above downwards and bluntly rounded. Somewhat 
