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

Abstract

SynopsisTwenty-eight specimens of the seed genusDolichospermahave been examined. Fourteen are assigned toD. sexangulatumLong; 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 namedD. pentagonumsp. 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 thatAnasperma burnenseLong is the mature prothallial seed developed from the ovuleEurystoma trigonaLong.Eurystoma angulareLong sometimes possesses five integumental lobes and the free apical lobes vary in length.Compressed megaspores macerated from cupules ofStamnostoma huttonenseLong sometimes have three abortive spores in a compact group at the apex.Ovules ofEccroustosperma langtonenseLong 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 ofCalathospermum fimbriatumBarnard 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.