BENNETTITALES 



77 



which project only i . 5 cm. beyond the disk, each bearing two lat- 

 eral rows of synangia along the rachis. This remarkable "reduction" 

 of the stamen set, as compared with that in Cycadeoidea, has inten- 

 sified the suggestion of an angiosperm connection. 



That the stamens of Bennettitales bore synangia of the ordinary 

 Marattia type (fig. 61) has been shown to be true of all the forms 



Fig. 61. — Cycadeoidea dacotensis: part of transverse section through unexpanded 

 microsporophyll, showing synangia with loculi arranged in two rows; some of the 

 loculi contain pollen grains; X25. — After Wieland (22). 



examined, including the older known European species. The struc- 

 ture of the synangia seems to be almost identical with those of Marattia 

 or of Danaea (fig. 62). Superficially there is a wall of heavy cells, 

 and between it and the sporangial chambers there is a more delicate 

 tissue. The sporangial chambers are separated from one another 

 by partitions consisting each of a single plate of cells, and form two 

 rows, between which the synangium dehisces in two valves. It is 

 evident that this structure has advanced little beyond the fern level, 

 and might well belong to Cycadofilicales or to Filicales. In fact, 

 the free portion of a microsporophyll, if detached, would certainly 

 be mistaken for a Marattia-like fern. This relatively stationary 

 character of the microsporangiate structures appears throughout the 



