The genus Purpuroidea was described by me in 1848 from three species in the Great Oolite of Gloucestershire, and published in the Annals and Magazine of Natural History, accompanied by woodcuts representing one of the Species. Before that period M. Buvignier had described and figured three species of the same genus from the Coral Rag of France, Mem. Soc. Philomath. Verdun, 1843, accompanied by plates illustrating the Species, which he assigned to the genus Purpura; these figures were for the most part insufficient for the purposes of generic discrimination, and founded upon specimens more or less imperfect; one of them was believed by me to be identical with the species figured in my woodcut, and was accordingly named by me Purpuroidea nodulata, the name of the Species having been adopted from the Murex nodulatus of Young and Bird, which was also believed to be identical with the Gloucestershire species.