536 



STUDIES IN FOSSIL BOTANY 



flower, with a central superior gynsecium, a whorl of 

 hypogynous stamens, and an enveloping perianth. 



The anatomical structure of the microsporophylls 

 has not yet been fully investigated, but it is known 

 that two ranks of vascular bundles are present in 

 the connate disc, and that a considerable number 



Fig. cio. — Cyca'ieoidca dacotensis. — Transverse section through rachis of a sporo- 

 phyll and adjacent synangia. The middle and lower synangia are cut transversely, 

 the upper very obliquely. The palisade-layer, walls of the loculi, and spores are all 

 shown. X about 2s. From Wieland. 



enter each rachis as it becomes free. The general 

 arrangement of the bundles is compared with that in 

 the rachis of a Cycad leaf. 



The synangia, as already mentioned, are inserted 

 in two rows on each pinna ; their insertion is described 

 by Dr. Wieland as "sub-lateral." Such a position is 

 common on the modified fertile fronds of Ferns, where 

 the insertion of the sporangia on the lower surface, usual 



