The Morphology of a New Species of Pteridosperm Seed from the Yorkshire Coal Measures

Abstract

The paper gives an account of the morphology of a hitherto undeacribed pteridosperm seed the specimens of which come from the Yorkshire Coal Measures and for which the name Physostoma stellatum is suggested. Structurally it resembles Physostoma elegans in possessing an integument which, apically, consists of a number of separate segments and in the fact that the apex of the megaspore and its associated nucellar tissues bulge into the base of the pollen chamber. It differs from that species in a number of other characters which justify separate specific rank.