THE GREAT GROUPS OF PTEEIDOPHYTES 



165 



The solitary sporangium appears in the axils (upper 

 angles formed by the leaves with the stem) of the leaves 

 and sporophylls, but arise from the stem instead of the 



Fig. 139. Selaqinella MarteTisii; A, brancli bearing ptrobili; B, a microsporophyll 

 witli a microsporangiunl, showing microspores tiirongh a rupture in the wall; C, 

 a megasporophyll with a megasporangium ; D, megaspores : E, microspores. — 

 Caldwell. 



29 



