xxxvn] 



WILLIAMSONIA 



437 



discovered by Prof. Nathorst in the Lower Estuarine series of 

 Wlutby ; it has also been obtained from beds of the same age at 

 Marske in the Cleveland district of Yorkshire^- WilUamsonia 

 spectabilis, though indubitably a male organ, has not been found 

 attached to a stem, and there is no decisive evidence as to its 

 connexion with a particular species of frond. Nathorst beUeves 

 that it belongs to the plant which bore the leaves known as 



Fig. 551. Williamsonia spectabilis and leaves of Ptilophyllum pecten. (Aftep 

 Nathorst; f nat. size.) 



Ptilophyllum pecten, an opinion based chiefly on association. 

 The more complete specimens consist of a broad funnel-shaped 

 organ prolonged below into a slender stalk and divided at the 

 margin into several hnear-lanceolate segments (microsporophyUs) 

 the apices of which were roUed inwards like young fern-fronds 

 (figs. 551, 552). The synan^a agree closely in form and in such 

 structural features as can be made out from cuticular preparations 

 with those described by Wieland in American species of Cyca- 

 deoidea ; they are sHghtly reniform, 5 — 6 mm. long and 2 mm. 

 broad and divided into several locuh by transverse partitions 



1 Thomas (13^) p. 230, PI. xxiv. figs. 1—3. 



