IV.—The Rotiform Bryozoa of the Isle of Wight

Abstract

A Small fossil with a wheel-shaped body borne on a narrow stem has long been known from the base of the Holaster planus zone in the Isle of Wight. It has been recognized as one of the Bryozoa, but has not been described, although once recorded as “near Defrancia diadema, Hag.” It has also been recorded by Dr. A. W. Rowe as “the beautiful little rotiform Bryozoon.”The following diagnosis has been lying unpublished for eight years in the manuscript of the second volume of the Catalogue of Cretaceous Bryozoa in the British Museum. A preliminary account of the species is now issued, as the name is wanted for reference in the course of Dr. A. W. Rowe's forthcoming memoir on the Chalk of the Isle of Wight. A fuller account of the species with illustrations, on plates drawn in 1900, will be given in the Catalogue, which it is hoped will be issued during this Winter.Blcavea Rotaformis, n.Sp.Diagnosis.—Zoarium simple or compound, with a narrow cylindrical stem, attached in a circular concavity in the lower part of the body. The body of the zoarium is discoid, or wheel-shaped, and has on the margin a series of vertical radial projections like cog-wheels. The cogs usually project for a distance nearly equal to the radius of the disc. The cogs may be prolonged at their upper, outer corner into spike-like fasciculi. The upper surface between the bases of the fasciculi is depressed, and occupied by the small, crowded, irregular apertures of the intermediate, subordinate zoœcia.