XXXVI] CYCADEOIDEA 371 



branches would be contingent on a certain stage of development 

 and not a generic character. Dr Stopes 1 has recently published 

 facts with regard to the anatomical features of Cycadean stems 

 which have a bearing on the vexed question of nomenclature, 

 but are more important from a morphological point of view as 

 they indicate a closer agreement between certain types of Lower 

 Cretaceous stems and those of Cycas and other recent genera, in 

 which successive rings of vascular tissue are developed, than has 

 previously been recognised. In her diagnosis of Cycadeoidea 

 she includes the following statement: 'In its internal anatomy 

 the trunk shows two or more (up to eight are recorded) zones of 

 secondary wood, the zones composed of distinct series of tracheids 

 each more or less regularly arranged in radial sequence.' It is 

 claimed that the addition of this character constitutes for the 

 first time a clear distinction between Cycadeoidea and Bennettites. 



<J 



Dr Stopes states that the two stems on which Buckland founded 

 the genus Cycadeoidea are lost and adds that Buckland' s type 

 has certain anatomical features which are not found in Bennettites. 

 Buckland in his description of C. microphylla states that there 

 are 'two laminated circles' in the stem instead of the usual single 

 cylinder, a character suggestive of Cycas. In the original figure 

 of this species there are no indications of any lateral fertile shoots 

 though, as Dr Stopes says, many of the Portland stems undoubtedly 

 possessed such flowers. This author makes no reference to Buck- 

 land's later description of C. microphylla: in this it is stated 

 that the stem bears numerous buds rising from the axillae of 

 petioles, and these are shown in the illustration 2 . Without access 

 to the actual specimen it is impossible to say whether or not the 

 two 'laminated circles' described and figured by Buckland 3 are 

 two distinct cylinders or parts of one cylinder separated by the 

 infiltration of some inorganic substance. In his description of 

 Cycadeoidea Yatesii Carruthers spoke of the occurrence of two 

 cylinders of wood, and this was confirmed in a subsequent account 

 of the type-specimen 4 . Dr Stopes gives a fuller account of Car- 

 ruthers' type and re-confirms the existence of two vascular 



1 Stopes (15) p. 309. 



2 Buckland (37) A. Vol. n. p. 98, PL LXI. fig. 1. 



3 Ibid. (28) PL XLIX. 4 Seward (95) A. p. 166. 



242 



