bennp:ttitales 



69 



forks of the widely spreading branches (also in Wielandiella), evi- 

 dently being terminal structures, and the narrow j)innate leaves, only 

 7-8 cm. long, form '■osettes about the forks. In general habit, there- 

 fore, the Bennettitales show a range that may well connect the more 

 open, branching forms of the Cycadofilicales with the very compact 

 and usually simple body of the Cycadales. It has been suggested 

 (29) that Benncttites (Cycadeoidea) and W illiamsonia may be regarded 

 as representatives of two groups of Bennettitales. 



Ftg. 57. — WiUiamsonia{Anoinozamites) angustifolia: branching trunk, with rosettes 

 of leaves and strobili at the forks; about \ natural size. — After Nathorst (17). 



A second striking external feature of the Bennettitales is the 

 occurrence of scales densely packed between the leaf bases and about 

 the strobili, and also covering the crown. This is distinctly 

 the so-called ramentum of ferns, the scales being one layer of cells 

 thick, except in the central region, the cells becoming much elongated 

 (fig. 58). In certain species of Cycadella, a dwarf genus distinguished 

 by its abundant ramental covering. Ward and Wieland describe 

 the ramentum and armor of leaf bases as making up half the bulk 

 of many trunks. While ramentum is not lacking in any of the Ben- 

 nettitales, so far as known, there is every gradation in its abundance, 



