Terebratula oblonga

Sowerby, J. De C. (1826-1835). The mineral conchology of Great Britain; or coloured figures and descriptions of those remains of testaceous animals or shells, which have been preserved at various times and depths in the Earth. Vol. VI. London, privately published, pp. 1-230 + index [231-235], pls 504-609. [pp. 1-86, pls 504-545 (1826); pp. 87-156, pls 546-580 (1827); pp. 157-200, pls 581-597 (1828); pp. 201-230, pls 598-609, index pp. 231-235 (1829); systematical index (1835)].