CTCADEAN STKMS. 43^ 



in a similar comprehensive sense, but these authors retain the 

 designation Bennettites for the species B. Oibsonianus, as we possess- 

 a fairly complete knowledge of the morphology of its female repro- 

 ductive organs. Since Carruthers' Bennettites was first described ' 

 several other examples of the same genus have been discovered ^ 

 in a state of preservation that admits of minute investigation of 

 the fertile shoots. There can he little doubt that the majority of 

 Mesozoio Cj'cads belong to the section Bennettitales, and bore repro- 

 ductive organs of the type represented by Bennettites Oihsommius. 

 In an earlier volume ^ I expressed the opinion that we should do' 

 more wisely to restrict the generic name Bennettites to stems 

 bearing the bennettitean inflorescence; the lateral reproductive 

 shoots are usually recognised without difficulty, and we may 

 safely assume, in cases where special lateral branches are present,, 

 that they bore flowers similar to those of Bennettites Oibsonianus. 

 There are, however, various forms of trunks which present no- 

 signs of lateral fertile shoots ; they bear a close resemblance to- 

 the common type of recent Cyoadean stem in being covered with 

 a thick envelope or armour of persistent petiole-bases. 



Stems of this category have been described as species of Cycaieoidea, 

 Bueklandia, Yatesia, and other genera. Lester Ward, in a paper' 

 dealing with A Revision of the genus Cycadeoidea of BucUand,* 

 refers to the persistent character of the leaf -bases in Yatesia, Fittonia, 

 and Platylepis, as a feature distinguishing them from Cycadeoidea. 

 This distinction is, however, hardly a valid one. The stem of 

 Cycadeoidea, using the term in the sense in which it is employed 

 by Ward and other authors, is covered with rhomboidal areas, 

 sometimes excavated by decay into hollow spaces bounded by 

 a sUicified mass of chaffy ramenta, or presenting the appearance 

 of flat or convex areas ; these areas are the bases of petioles from 

 which the rest of the frond has been cut off by means of a definite 

 absciss-layer. In Yatesia, Fittonia, and other genera, the leaf-bases 

 may be in some cases more prominent, but I am unable to recognise 



1 Camithers (70). 



" For more recent descriptions of Bennettites, see Solms-Laubach (91') ; Liguier 

 (94), (03); Scott (00), p. 44S; Coulter & Chamberlain (01); Wieland (99), (99'). 

 3 Seward (95), p. 134. 

 ■1 Ward (94). 



