420 Dr. D. H. Scott. On Oheirostrobus, a new Type 



upturned foliaceous scale as well as a shorter and stouter downward 

 prolongation. 



Each of the fertile segments ends in a fleshy laminar enlargement 

 not unlike the peltate scale of an Equisetum or a Galamostachys. 

 These fertile laminae, which are protected on the exterior by the 

 overlapping ends of the sterile segments, bear the sporangia. Four, 

 perhaps in some cases five, sporangia are attached, by their ends 

 remote from the axis, to the inner surface of the peltate fertile lamina. 

 Each sporangium is connected with the lamina by a somewhat narrow 

 neck of tissue into which a vascular bundle enters. The sporangia 

 are of great length, and extend back along the pedicels until they 

 nearly or quite reach the axis. 



The sterile and fertile segments alternate regularly, one above the 

 other, in the same vertical series. So much is evident, but the ques- 

 tion which segments are fertile and which sterile, has presented great 

 difficulties, owing to the fact that the same segment can scarcely ever 

 be traced continuously throughout the whole of its long course, and 

 that the pedicels of sterile and fertile segments present no constant 

 distinctive characters. For reasons, however, which will be fully 

 given in a subsequent paper, I think it highly probable that in each 

 sporophyll the segments of the lower lobe are sterile, and those of 

 the upper lobe fertile, constituting the sporangiophores. 



The sporangia and pedicels are all packed closely together so as to 

 form a continuous mass. The external surface of the cone was com- 

 pletely protected by its double investiture of fertile and sterile 

 laminae. 



The spores are well preserved in various parts of the cone, and, so 

 far as this specimen shows, are all of one kind, their average dia- 

 meter being 0'065 mm. At the base of the cone, where macrospores, 

 if they existed, might naturally be looked for, the spores are of the 

 same size as elsawhere. So far, then, there is no evidence of hetero- 

 spory. The spores are considerably larger than the microspores 

 of the Lepidostrobi. Those of the Burntislaud Lepidostrobus, for 

 example, are barely 0*02 mm. in diameter. The spores of our plant 

 approach in size those of Sphenophyllum Dawsoni, or the microspores 

 of C 'alamo stacliys Gaslieana. 



The sporangial wall, as preserved, is only one cell in thickness ; it 

 bears no resemblance to the palisade-like layer which forms the wall 

 of the sporangium in Lepidostrobus, but has the same structure as 

 that of a C alamo stachys* The sporangial wall of Sphenophyllum 

 Dawsoni is similar. 



The anatomy of the axis of the cone agrees closely with that of 



* See Weiss, " Steinkohleu-Calamarien," yol. 2, 1884, Plate XXIV, figs. 3, 4, 

 and 5 ; Williamson and Scott, " Further Observations on the Organisation of the 

 Fossil Plants of the Coal-measures," Part I, ' Phil. Trans./ 1894, PL 81, fig. 31. 



