I. In the volume of the Palaeontographical Society for 1850, M. Milne-Edwards and M. Jules Haime state that Choristopetalum impar does not appear to them to belong to the class Zoantharia , but is in their opinion a Bryozoon*—the grounds of dissent not being however mentioned. When the description of the fossil, published in the Quarterly Journal of the Geological Society†, was under preparation, the author's attention was necessarily called to the class Bryozoa , in consequence of the generic name Heteropora having been assigned to some of the specimens previously to their coming into his possession; and it was not until all the detected structures had been carefully considered, that the fossil was referred to Zoantharia or Anthozoa . In the description, the visceral receptacles are stated to be tubular, and the tubes to be crossed at irregular levels in adjacent receptacles, by transverse laminae or diaphragms‡—‘tabulae’ of M. M.-Edwards and M. J. Haime; and these structures are carefully delineated by Mr. J. de Carle Sowerby in plate 4. fig. 6†, particularly as respects the diaphragms being on different levels (fig. 6† near the bottom and left side), the continuous line representing the boundaries of two concentric layers*. It is further stated more than once†, that transverse laminae are wanting in tubular Bryozoa or Ascidian polypes; but are characteristic of Anthozoa (Zoantharia) ; yet their existence in the lower greensand fossil is not denied by M. M.-Edwards and M. Haime. In the specimens examined, the structured was frequently absent, being one of the