52 Bower.—Studies in the Phytogeny of the Filicales. VIL 
departed from, and that is the case also in D. dissecta. Fig. 37, c, repre¬ 
sents in outline the sorus of the latter in a more mature state. The 
indusial lips gape widely; the flattened, but still convex, receptacle bears 
Fig. 37. a. Pinnule of Dennstaedtia dissecta seen in surface view, showing marginal sori 
on the apex of the anadromic branches of the veins. ( x 4.) b. Sorus very young, cut in vertical 
section, showing the marginal receptacle and superficial indusial flaps, (x 150.) c. Mature sorus 
in vertical section, (x 35.) 
numerous sporangia, and the stalks of others already dehisced. The latter 
are mostly near the centre, while younger sporangia are nearer the margins. 
Thus there is a general indication of a basipetal sequence, but the mixed 
character becomes obvious with age. The facts indicate that Dennstaedtia , 
and in a less degree Microlepia , are tran¬ 
sitional between a gradate and a mixed 
condition, but the relation downwards is 
clearly to the Dicksonieae, with which 
relation the anatomy and dermal hairs 
will also coincide. 
A comparison of the sorus of Hypo- 
lepis nigrescens shows in section a very 
similar outline (Fig. 38); but the curva¬ 
ture to the lower surface is stronger, 
the sorus is more definitely of the mixed 
type, while the generic character is the 
absence of the inner (abaxial) indusium. 
It may readily be interpreted as a more 
advanced derivative, the absence of the 
inner indusium being related to its pro- 
no longer needed, where the curvature is strong. But 
certain details from H. nigrescens. In some 
Fig. 38. Mature sorus of Hypolepis 
nigresce 7 is cut vertically, showing its mixed 
character and the absence of the inner 
indusium. (x 85 ) 
being 
tection 
Hypolepis repens differs in 
