11.—Some Observations on the Fertile Parts of Zosterophyllum myretonianum Penhallow from the Lower Old Red Sandstone of Scotland

Synopsis New collections of Zosterophyllum myretonianum Penhallow have been made at a number of localities in the Lower Old Red Sandstone of Scotland. For the first time, details of the fructification are recorded and incorporated into an emended diagnosis of the species. A comparison with the remaining species of Zosterophyllum indicates that sporangial and stalk characteristics are most important in delimiting Z. myretonianum. Tentative explanations for the wide variation in the overall morphology of the fructifications are put forward.