The complex shape of the leaf called Brittsia problematica suggests a floating life habit. The rachis and the pinna axes are flattened. The pinna axes have lateral lobes extending in the plane of the axes. The pinnules are lacerated and extend out of this plane. Several of the above mentioned characteristics of Brittsia are similar to those described by Phillips and Andrews (1968) from the fertile frond portion of Biscalitheca. Therefore, it becomes more likely that Brittsia is a coenopterid fern belonging to th Zygopteridaceae Includes bibliographical references (p. 322) The complex shape of the leaf called Brittsia problematica suggests a floating life habit. The rachis and the pinna axes are flattened. The pinna axes have lateral lobes extending in the plane of the axes. The pinnules are lacerated and extend out of this plane. Several of the above mentioned characteristics of Brittsia are similar to those described by Phillips and Andrews (1968) from the fertile frond portion of Biscalitheca. Therefore, it becomes more likely that Brittsia is a coenopterid fern belonging to th Zygopteridaceae Fieldiana series has been published as Geological Series by Field Columbian Museum (1895-1909) and Field Museum of Natural History (1909-1943), and as Fieldiana: Geology by Chicago Natural History Museum (1945-1966) and Field Museum of Natural History (1966-)