XXXVII] CYCADOCEPHALUS 473 



In habit WiUiamsonieUa resembles Wielandiella : in the lattei 

 genus the foliage-leaves were confined to portions of the stem near 

 the forks, while in WiUiamsonieUa they were more uniformly 

 scattered: Wielandiella bore leaves of the Anomozamites form 

 while WiUiamsonieUa flowers are always associated with Taenio- 

 pteris fronds. The much greater spore- output of Williamsonia 

 may, it is suggested by Thomas, be correlated with the unisexual 

 nature of the flowers of that species. The microsporophylls of 

 WiUiamsonieUa differ in their more reduced form from the pinnate 

 microsporophylls of Williamsonia, e.g. W. spectabilis, and agree 

 more closely with those of Wielandiella. The microsporophylls 

 of WiUiamsonieUa are free and not connate at the base as in 

 Cycadeoidea and Williamsonia. In its pyriform axis WiUiam- 

 sonieUa resembles Williamsonia qiqas and differs from Williamsonia 



*J O 



Leckenbyi in the possession of a sterile apical corona: WiUiam- 

 sonieUa has megasporophylls and microsporophylls both of which 

 appear to be functional, while in Cycadeoidea fully developed 

 microsporophylls occur in association with megasporophylls which 

 are immature and must have matured much later than the micro- 

 sporophylls. The new genus agrees with Williamsonia in its 

 general features, but the flowers are smaller and are characterised 

 by the considerable reduction and simplification of the male 

 organs. 



CYCADOCEPHALUS. Nathorst, 



This genus was founded 1 on a specimen from the Lower 

 Rhaetic of Scania, at first regarded as a megastrobilus and on 

 further examination 2 found to be a collection of microsporophylls 

 resembling those of Williamsonia and Cycadeoidea. The type- 

 species is Cycadocephalus Sewardi, and a second species, C. minor, 

 was subsequently discovered by Dr Halle at a slightly higher 

 horizon in the Rhaetic series. Prof. Nathorst's most recent 

 account of the genus affords a striking illustration of the possi- 

 bilities of the method, which he has employed with conspicuous 

 success, of investigating carbonised fossils by mears of cuticular 

 preparations. 



1 Nathorst (02) p. 7, PI. 1. 



2 Ibid. (09) p. 27, PL vm. ; (12 2 ) Pis. i., ii; (12). 



