XXXVIII] BTJCKLANDIA 481 



of which are practically identical with the cast of a recent pith 

 reproduced in fig. 398. Casts of the pith preserved as separate 

 fossils are included in the genus Cycadeomyelon. 



There is evidence of the occurrence of more than one zone 

 of vascular tissue in a stem from Lower Greensand beds of Bed- 

 fordshire described by Carruthers as Yatesia Morrisii 1 (= Buck- 

 landia Yatesii), and Dr Stopes 2 has recently described a species, 

 B. buzzardensis (fig. 578), with several zones of conducting tissue. 

 This feature has not so far been satisfactorily demonstrated in 

 Cycadeoidea. An Indian species, Bucklandia indica, shows that 

 the secondary xylem is more compact than in typical Cycadeoidea 

 stems, and the tracheids have multiseriate pitting. 



Two long and narrow stems figured by Nathorst from the 

 Rhaetic . of Scania as Bucklandia Saportana 3 differ from other 

 species in the irregular arrangement of the leaf-bases which in 

 certain regions are crowded as in the typical example of the 

 genus shown in fig. 576, but in the intervening portions of the 

 stem they are few in number and widely separated by the finely 

 striated bark. This type, though similar to some specimens of 

 English, Mexican, and Indian Bucklandias in the zonal differences 

 in the leaf-bases, represents an extreme case of the alternation 

 of smaller and crowded and larger and scattered leaf-scars. It 

 is by no means unlikely that Bucklandia Saportana forms a transi- 

 tion between Bucklandia and the stem of Wielandiella described 

 by Nathorst from the same region : in Wielandiella the leaf-scars 

 are concentrated at the region of forking but a few occur elsewhere : 

 in B. Saportana there is no evidence of branching and in this 

 respect it differs from Wielandiella. 



Bucklandia anomala (Stokes and Webb). 



This species, from Wealden beds in Sussex, was first described 

 by Stokes and Webb 4 as Clathraria anomala, and the same type 

 was figured by Man tell and other authors as Clathraria Lyelli. 

 The specimens referred by Carruthers to Bucklandia anomala and 

 B. Mantelli 5 do not exhibit any well defined specific differences, 



1 Carruthers (67); (70) p. ,688. 2 Stopes (15) p. 309. See postea, p. 486. 



3 Nathorst (86) PL xvm. fig. 5. 



4 Stokes and Webb (24) Pis. xiv. xvn. 



5 Carruthers (70) p. 686, PI. LIV. See also Seward (95) A. p. 123. 



S. ill 31 



