HYPOLEPIS, ETC. 



[CH. 



be reflexed in some examples, in others it is expanded in the plane of the 

 pinnule (compare Fig. 582, B, D, with Fig. 586). The latter state appeared 

 in my Jamaican specimens, in which the sorus is considerably spread along 

 the vein, and this instead of terminating at the receptacle extends an ap- 

 preciable distance onwards into the rounded marginal lobe that represents 

 the upper or adaxial indusium (Fig. 586). It is this lobe which in typical 

 forms of H. repens curves over and protects the sorus. A vertical section 

 through such a sorus as that of Fig. 586, following the vein, shows how 

 greatly the receptacle is extended and flattened, while the vein is seen con- 

 tinued far into the distal indusial flap (Fig. 587, a). If, in the presence of these 

 palpable differences, any doubt were felt as to a real relationship between this 

 type of H. repens and those Dennstaedtioid Ferns which have both indusia 



Fig- 587- rt=young sorus of Hypolepis repens cut 

 vertically: ?/./. = upper indusium, traversed by a 

 vascular strand: vA. = vestigial lower indusium ( x 15). 

 (^ = small part of the soral surface, including the vesti- 

 gial indusium {v.i.), more highly magnified { x 160). 



present, the fact that a vestigial lower indusium may sometimes be found 

 would remove it. Such a vestige is seen in Fig. 587, v.i. Often, however, the 

 inner indusium is altogether absent, the sorus appearing superficial upon the 

 vein, and distinctly intra-marginal. This is the characteristic of the Fern now 

 designated, in Christensen's Index, Dryopteris {P.)punctata (Thunbg.) C. Chr. 

 It has been variously ascribed to Polypodiuni, Phegopteris, Hypolepis, Nephro- 

 ditim, etc. Many authors have noted how impossible it is to draw a definite 

 line between certain Ferns ranked as Polypodiuin and Hypolepis. In particular 

 Sir Joseph Hooker remarks on Hypolepis in the Flora Tasmaniae (Vol. II, 

 p. 138) that "sometimes the reflexion of the pinnules' margin is so slight 

 that the sorus is really naked, and then I cannot distinguish the genus from 

 Polypodinvi, or the species H. tenuifolia from P. riigulosum Lab." Mr Carse, 



