SIGILLARIOSTROBUS 235 



the upturned laminar portion of the sporophyll, or 

 possibly it may have been covered in by an indusium, 

 as in Isoetes. The sporangia contain large megaspores, 

 with an echinulate membrane (see Fig. 96, C). It 

 would appear, therefore, that the sporangia of Sigillaria, 

 in their form and mode of insertion, resembled those of 

 Lepidostrobus, while differing from those of Spencerites 

 or of Sigillariostrobus Crepini, which should perhaps be 

 removed from its present genus. 



A fine granulation, strongly suggesting the presence 

 of small crowded microspores, was observed by the 

 same investigator in the sporangia of another specimen, 

 which at the same time showed distinct megaspores in 

 other parts. If this indication is to be relied on, it 

 follows that Sigillariostrobus, like so many forms of 

 Lepidostrobus, bore both kinds of spore on the same 

 cone. 



The discovery of the fructification of Sigillaria 

 affords an explanation of certain scars which have long 

 been known to occur occasionally on the stems, either be- 

 tween the vertical rows of leaf-scars, or scattered among 

 them in the same series. These scars occur on all forms 

 of Sigillarian stem. Fig. 87 (p. 208) represents them 

 (c.s.) on the surface of S. mamillaris , which is of the 

 Rhytidolepis type. Each scar has a central print, no 

 doubt corresponding to a vascular strand, the structure 

 of which has been demonstrated by Mr. Kidston in the 

 case of 5. elegans (see p. 228). In one case, small 

 leafy shoots, the dimensions of which agreed well with 

 those of the peduncles of the cones, are said to have 

 been found seated on the scars. It is therefore reason- 

 able to assume that we have in these marks the prints 



