Bower.—Studies in the Phytogeny of the Fihcales. 517 
this appearance is shown from both sides, it follows that the stalk has the 
unusual composition of four rows of cells, a point definitely demonstrated 
by transverse sections. Text-figs. 16, e and f show sporangia seen ob¬ 
liquely from the side, the first from the side of the stomium, the other from 
the completely indurated side. From these various views the structure of 
the sporangium will be fully realized. The similarity of form, and in 
certain features of the annulus, to that of G. lineata is obvious ; but though 
the annulus remains oblique, as in that Fern, its induration is incomplete, 
Text-figs. 16, a-f. Various aspects of the sporangia of Dipteris Lobbiana. 
For description see Text, x 50. 
while the stomium has swung into a lateral position ; and the stalk is 
of a less complex construction. 
The sporangium of Cheiropleuria is larger, and longer-stalked than that 
of Dipteris , but the general type of it is the same, a very distinctive point 
of similarity being the four-rowed structure of the stalk. This is clearly 
shown by tangential sections of the soral area, in which the sporangial stalks 
appear densely surrounded by paraphyses (Text-fig. 17,^). Seen from the 
‘peripheral’ side the sporangium appears as in Text-fig. 17. a, associated 
with paraphyses, which are longer than itself until maturity is reached. 
The stalk shows two rows of cells, which become slightly constricted below 
