186 CARBONIFEROUS LAMELLIBRANCH1ATA. 



the Carboniferous period at all. It is labelled " Derby, Martin ; " but the matrix 

 is unlike anything with which I am acquainted in the Carboniferous series of this 

 county ; and it is very possible that the shell was obtained from the drift. The 

 town of Derby is situated on Triassic and not on Carboniferous strata. 



The type is preserved in the Sowerby Collection at the British Museum (Nat. 

 Hist.), Cromwell Road ; I am indebted to the authorities for permission to 

 refigure the specimen. As I have never seen anything like this shell from 

 Carboniferous beds, I retain the species with great hesitation, and for the simple 

 reason that the type specimen is preserved in the National Collection. Sowerby 

 gives very little information about the specimen, simply stating, " This is 

 probably a rare shell; it is from Mr. Martin's collection of Derbyshire fossils, 

 though not figured by him." Quenstedt refers to this specimen amongst his 

 Liassic shells (' Der Jura,' 1858, p. 110, pi. xiii, fig. 42). Hence, for the present, 

 it is impossible to arrive at an exact conclusion as to the horizon whence this 

 specimen was obtained. 



Nucula lucinifoemis, Phillips, 1836. Plate XIV, figs. 17 — 22. 



Nucula lucinifoemis, Phillips, 1836. Illustr. Geol. Yorkshire, pt. 2, p. 210, 



pi. v, fig. 11. 

 Non Cabdiomobpha ? lucinifoemis, de Koninck, 1842-4. Foss. Carbonif. Belg., 



p. 107, pi. ii, fig. 10 ; pi. iii, fig. 13. 

 Nucula lucinifoemis, Morris, 1843. Catal. Brit. Foss., p. 94. 



— — Brown, 1849. Illustr. Foss. Conchology, p. 187 (figures 



wanting). 

 Cabdiomobpha axinifobmis, d'Orligny, 1850. Prodr. Paleontol., p. 133. 

 Leda lucinifoemis, de Rychholt, 1853. Melanges Paleontol., 2e partie, p. 150. 

 Nucula lucinifoemis, Morris, 1854. Cat. Brit. Foss., 2nd edit., p. 216. 



— — M'Coy, 1855. Brit. Palseoz. Rocks and Fossils, p. 512. 



— — Young and Armstrong, 1871. Trans. Geol. Soc. Glasgow, 



vol. iii, Appendix, p. 53. 

 Ctenodonta lucinifoemis, Bigshy, 1875. Thesaur. Devonico-Carboniferus, 



p. 303. 

 Nucula lucinifoemis, JEtJieridge, 1885. Brit. Foss., part 1, Palseoz., p. 287. 



Specific Characters. — Shell somewhat obliquely subovate, short, very mode- 

 rately gibbose in front, compressed behind. The anterior end is short, and almost 

 limited to the anterior-superior angle by the rapid curvature downwards and 

 backwards of its border. The inferior border is very convex downwards, and its 

 posterior limb, which is shorter than the anterior, meets the posterior border at a 

 rounded obtuse angle. The posterior border is almost straight, transversely cut 

 from above downward and backward. The hinge-line is as long as any transverse 

 diameter, and is almost straight in its posterior and longer portion ; the anterior 



