6 Bower.—Studies in the Phytogeny of the Filicales. VIL 
leaves are unbranched, like the juvenile leaves of Marsilia, and the dicho¬ 
tomies of the fertile leaf are developed on the same scorpioid scheme as the 
adult sterile leaves of Marsilia , differing only in the number of the forkings. 
These very suggestive parallels strongly support the comparison already 
Fig. 4 a , b. 
CL 
it} 
Young leaves of Schizaea rupestris, showing circinate vernation, with the 
pinnae reflexed to the convex (abaxial) side, (x 6.) 
/V 
Fig. 5. i-viii. Transverse sections of very young pinnae of Schizaea rupestris , showing the 
marginal origin of the sporangia, which are very soon turned towards the lower (abaxial) surface. 
In vi, vii the origin of the indusial flaps can be seen, right and left, near the bases of the sporangia, 
(x 85.) 
instituted on other grounds. The circination of the young leaves is of the 
usual type, with the adaxial surface concave; but the pinnae are folded 
backwards, so that they radiate outwards from the rachis, like the spokes of 
a wheel. Their lower surface, to which the sporangia are directed, faces 
inwards (Fig. 4, a, b). Transverse sections of the pinnae show the 
marginal segmentation when very young (Fig. 5, i), but almost at once 
