

OF LOWER GJlEEXSAtfD PLANTS. 25 



Scott's detailed botanical work in the ' Studies ' and Wieland's 

 volume give the fullest accounts, to which reference is constantly 

 made. 



The American forms described by Wieland (1906, 1911, etc.) 

 are all named Cycadeoidea, Buckland, 1823. As in some of the 

 American species, the fruits are practically identical with the 

 British form B. Gibsonianus, it is clear that Cycadeoidta as used 

 by the American, and Bennettites as used by the British palaeo- 

 botauists are largely synonymous. I favour the use of the 

 generic name Bennettitfs for the forms in which the internal 

 anatomy and fructifications coincide with Carruthers's type *. 



For a history of the older views published from time to time 

 reference should be made to the resumes in Seward (1895), 

 Wieland (1900), and Berry (1911). 



The general external form of the fossil can be seen in PL I, 

 and is well illustrated in the fine series of photographs published 

 by Wieland (1906). The details of stem and fruit anatomy are 

 described for the Lower Greensand species in the following 

 pages, and they can be taken as typical of the genus ; but to 

 supplement them mention must be made of the important 

 features discovered by Wieland in the less mature American 

 fructifications. These structures were probably present in the 

 younger states of the Lower Greensand form, of which, however, 

 we have no specimens. 



Wieland publishes many diagrams which make the structure 

 of the complete fructification clear, and two of these are repro- 

 duced in text-figs. 6 & 7. The term " flower " has been applied 

 to the fructification because of its complex organisation and 

 bisexual nature. Essentially it consists of a stout central axis 

 which bears series of sterile bracts, in a variable number up to 

 about 100, in close spiral series (see text-fig. 6). 



Above the sterile bracts comes a whorl of microsporophylls. 

 Of these there is a relatively small number, variable in the 

 different species, but generally under twenty. At the base they 

 are confluent, but each separate microsporophyll expands to 

 form a large and pinnately compound structure, up to almost 

 10 cm. long. On each of the lateral pinriaB rows of sporangia are 

 borne, varying in number according to the position on the leaf, 



* See Appendix, p. 295, 



