xxxvn] 



WILLIAMSONIA 



435 



Williamsonia gigas (Microsporophylls). 



In the course of an examination of the Williamsonia specimens 

 (from Yorkshire) in Paris in July of last year (1914) Mr Thomas^ 

 found a specimen previously overlooked, which is undoubtedly 

 either a male flower or, as I am inclined to think, the staminate 

 disc of a bisporangiate flower of Williamsonia gigas. The nature 

 of the matrix shows that it came from the neighbourhood of 



Fia. 549. Williamsonia gigas. A, diagrammatic drawing showing the position 

 of the synangia, at 8, and part of the staminate disc. B, a single synangium; 

 X 6. (After Thomas.) 



Whitby. It consists of an urn-shaped organ formed of the con- 

 crescent bases of 18 — 20 microsporophylls each 7 — 8 mm. wide ; 

 the cup is 5 — 6 cm. broad, the base being torn but tapered 

 (fig. 549) as though originally prolonged downwards into a stalk 

 as in W. Sfectabilis. Along the middle line of each sporophyll 

 is a series of depressions, probably the same in nature as those 

 on W. whitbiensis described by Nathorst, though it is not clear 

 whether, in this case at least, they represent aborted synangia. 



1 Thomas (15). 



28—2 



