386 BENNETTITALES [CH. 



netti tales. The occurrence of the genus Williamsonia in many 

 European localities as well as in India, Afghanistan, and other 

 countries, and the not infrequent occurrence of stems assigned to 

 Bucklandia, Yatesia, Cylindropodium, and other genera furnish 

 evidence of the rich development of the Bennettitales in later 

 Jurassic and Lower Cretaceous floras. Wieland's recent discovery 1 

 of numerous Cycadean fronds, Williamsonia flowers, and stems in 

 Liassic rocks in Mexico shows that the group had already assumed 

 an important position in the early part of the Jurassic period. 



The memoir by Carruthers 2 on British Cycadean stems contains 

 the first account of the morphological features of Bennettitalean 

 flowers based on petrified material. In 1891 Solms-Laubach 

 contributed an important paper on the Bennettitean flower 

 and several years later Lignier 3 contributed additional data 

 derived from a careful study of a well preserved strobilus 4 from 

 the Gault of Normandy. Wieland's researches 5 added very 

 greatly to our knowledge, particularly with regard to the morpho- 

 logy of the microsporophylls. Among the earlier descriptions 

 of the reproductive organs of the Bennettitales is Buckland's 

 account 6 of a specimen from the Inferior Oolite of Charmouth, 

 Dorset (fig. 560), which he referred to the genus Podocarya 

 (= Williamsonia Bucklandi 7 ) : a thorough examination of the type- 

 specimen, which unfortunately cannot be found, would probably 

 furnish many important facts. 



\Cycadeoidea (Bennettites) Gibsoniana (Carruthers). 

 )Cycadeoidea (Bennettites) Saxbyana (Brown). 



These two species serve to illustrate the type of stem for which 

 Carruthers instituted the tribe Bennettiteae and the genus 

 Bennettites. Bennettites Gibsonianus is the most important of the 

 five species described by Carruthers 8 , as it was from its fertile shoots 

 that information was first obtained as to the nature of the ovulate 

 strobili of the Bennettitales. B. Saxbyanus 9 , originally described 



1 Wieland (13). 2 Carruthers (70). 



3 Lignier (94 2 ). 4 See page 395. 



6 Wieland (06). 6 Buckland (37). 7 See page 448. 



8 Carruthers (70). 



9 Ibid. p. 698; for other references, see Seward (95) A. 139. 



