Royal Society, London. 237 



The segments are ot* two kinds — sterile and fertile. Both 

 alike consist ot a long, straight, slender pedicel, running out 

 horizontally, and terminating at the distal end in a thick laminar 

 expansion. The sterile segments are the longer, and their laminae 

 bear an uptumed tbliaceous 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 ot an Equisetum or a 

 Calamostachys. These fertile laminae, wich 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, at 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 vas- 

 cular bündle 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 

 question 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 ot sterile and fertile segments 

 present no constant distinctive characters. For reasons, however, 

 which will be fully given in a subsequent paper, 1 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 continuons mass. The external surface of the cone 

 was completely protected by its double investiture of fertile and 

 sterile laminae. 



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

 and, so fa'r as this specimen shows, are all of one kind, their 

 average diameter 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 elsewhere. So far, then, there is 

 no evidence of heterospory. The spores are considerably larger 

 than the microspores of the Lepidostrobi. Those of the Burntisland 

 Lepidostrobus, for example, are barely 0,02 mm in diameter. The 

 spores of our plant approach in size those of Sphenophyllum 

 Dausoni, or the microspores of Calamostachis Casheana. 



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 Calamostachys. 1 ) The sporangial wall of Sphenophyllum 

 Dawsoni is similar. 



x ) See Weiss, „Steinkohlen-Calamarien." Vol. II. 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, PI. 81, fig. 31.) 



