FURTHER OCCURRENCES OF SPENCERITES FROM THE MIDDLE PENNSYLVANIAN OF KANSAS AND ILLINOIS

Abstract

New specimens of Spencerites moorei add knowledge of its sporophylls and method of sporangial attachment. The sporophyll consists of a slender pedicel which expands at its distal end into a fleshy, peltate, diamond-shaped head which bears a presumably fleshy lamina. The sporangium is attached through most of its length to the adaxial surface of the pedicel rather than distally as in S. insignis. It is suggested that the distal attachment shown in S. insignis may be derived through a phyletic shift from the pedicellate position. Additional specimens of Spencerites provisionally assigned to S. majusculus are also recorded. The spores are bilateral, monolete, and shaped like quadrants of a sphere. Two prominent wings extend along the two contact faces and the monolete mark is prominently raised, thus imparting a three-winged appearance to the spore. The axis consists of an exarch protostele and a cylinder of thick-walled outer cortex.