VII.—Eurystoma trigona sp. nov., a Pteridosperm ovule borne on a frond of Alcicornopteris Kidston

Abstract

Synopsis Ovules of Eurystoma trigona sp. nov. are described. Over 330 unpollinated ovules were found attached to a petrified megasporophyll which appears to be a juvenile form of Alcicornopteris Kidston. Each ovule is triangular in cross section and has three wing-like extensions of the integument. None shows a female prothallus. The possibility that Alcicornopteris represents the fertile foliage of Stenomyelon is discussed.