12.—Further Observations on some Lower Carboniferous Seeds and Cupules

Abstract

Synopsis Twenty-eight specimens of the seed genus Dolichosperma have been examined. Fourteen are assigned to D. sexangulatum Long; these possess six or seven integumental lobes which extend apically as free tentacles equal in length to the seed body except when damaged or broken off. Fourteen other specimens are named D. pentagonum sp. nov. These are smaller and usually have five integumental lobes (less commonly six or seven). Long apical tentacles have not been seen in this species. Evidence is adduced that Anasperma burnense Long is the mature prothallial seed developed from the ovule Eurystoma trigona Long. Eurystoma angulare Long sometimes possesses five integumental lobes and the free apical lobes vary in length. Compressed megaspores macerated from cupules of Stamnostoma huttonense Long sometimes have three abortive spores in a compact group at the apex. Ovules of Eccroustosperma langtonense Long were borne in small bunches (probably pendent) on short pedicels; one specimen of this seed shows three well-developed separate abortive spores around the apex of the functional megaspore. The cupule of Calathospermum fimbriatum Barnard shows a structure suggesting that it may have evolved from a pair of cupules. Twelve to fourteen ovules were sometimes formed in the entire cupule though most of these were probably abortive. Some possible seed embryos are described and discussed, and an outline classification of seeds in the order Lagenostomales is proposed.