OF LOWER GREEKS \> T D PLAXTS. 



35 



nature of cork. The numerous bundles subdivide, and in the 

 Museum sections they are cut in several directions and show 

 very well the fine spirals and scalariform thickening of the 

 wood-elements. These bundles, as described by Seward (1897), 

 are mesarch in structure, and are directly comparable with those 

 of existing Cycads. 



Ramenta are very numerous between tbe leaf-bases (see text- 

 fig. 11). In section these show 7 their multicellular scaly nature. 

 They appear much alike in all the species of this genus, and 

 have been well illustrated by Wi eland (1906). 



The external form of the foliage of B. Gibsonianus is not 

 known. There is little doubt, however, that it must have been 



Text-fig. \\.-SenneUlte8 Gibsoniantts, Can*. Leaf-base out across, showing 

 the incurved horseshoe of bundles, the large-celled ground-tissue 

 with gum-canals, and the ruinenta lying around it. X 2'6. After 

 Carruthers. 



one of the large and pinnate leaf-forms, of which so many 

 Mcsozoic impression-species are known. Allied species from 

 America show the most beautifully preserved young unfolded 

 leaves in section, which are illustrated and described by Wieland 

 (1906). 



In this species the only fructifications known are in an ap- 

 proximately mature state. The male organs of the " flower " 

 shortly described above for the genus, are therefore not known. 

 Nevertheless, Solms-Laubach, working with Capellini (see 

 Capellini & Laubuch, 1892), made remarkably acute deductions 



