428 BENNETTITALES [CH. 



Carr. This conclusion has since been confirmed by Nathorst 1 

 who succeeded in obtaining excellent preparations of the cuticular 

 membranes of interseminal scales and micropylar tubes (fig. 545), 

 demonstrating their very close agreement with those of the flowers 

 of Cycadeoidea. 



One of Williamson's 'carpellary discs' has been shown by 

 Nathorst to be a verticil of microsporophylls bearing synangia, 

 but both this author and Lignier 2 think that the two specimens 

 figured by Williamson as carpellary discs are distinct organs, 

 one being a staminate whorl and the other a sterile infundibuli- 

 form organ. My own view is that both are of the same nature 

 and consist of microsporophylls. 



FIG. 544. Williamsonia gigas. Portion of a flower showing the protective bracts, 

 the annular zone formed by numerous sterile sporophylls and interseminal 

 scales, and the large central cavity originally occupied by the receptacle. 

 (From a specimen in the Williamson collection, Cambridge Botany School; 

 nat. size.) 



Fig. 544 represents the usual form in which the flowers of 

 W. gigas are found ; it consists of linear bracts covered with hairs 

 identical with those on the peduncles shown in figs. 541 543; 

 they surround a pyriform axis and form what Williamson called 



1 Nathorst (09) (11). 2 Lignier (07). 



