BENEDICT: GENERA OF THE FERN TRIBE VITTARIEAE 175 
.in A. semicostatum is rather a parallel development than an 
indication of direct relationship with Polytaenium. A. semicosta- 
tum is very clearly related to the other Antrophyums. 
As far as the characters of the mature sporophyte are con- 
cerned, Antrophyum seems to resemble most certain of the more 
divided forms of Hecistopteris. (Compare PLATE 4, FIG. 4, 5, etc., 
with PLATE 2, FIG. 6.)- The leaves of Hecistopteris here referred 
to, possess a type of venation which is easily comparable with that 
of Antrophyum nanum Fée, shown in the last figure. 
It is this type of venation, i. e., that of A. nanum, which is 
found in more or less modified form in all the larger species of 
Antrophyum. It is a type that seems to be better adapted than 
the Polytaenium type to the development of broad-leaved species, 
as Antrophyum includes at least two forms with orbicular blades 
and several others approaching this shape. One other interesting 
consequence of this dichotomous venation is to be noted, i. e., 
the leaf blade in all but a few species is broadest above the middle. 
In Polytaenium the blades are usually parallel-sided or elliptic. 
In the characters other than those of venation there is consid- 
erable variation in Antrophyum, and because of a conjunction of 
several of these variations in connection with geographic isolation, 
I have separated a group of three or four species as a distinct 
subgenus, Antrophyopsis, native in southern Africa and adjacent 
islands. The differences are stated below in connection with each 
character. 
The soriation in Antrophyum proper is variable between the 
limits shown in FIG. I of PLATE 7, and FIG. 2 of PLATE 6, respec- 
tively; that is, the sporangia may be borne either in single lines 
of greater or less extent (PLATE 7, FIG. I and 7), or they may be 
in lines that branch considerably (PLATE 7, FIG. 11). Always 
in Euantrophyum they are sunk in grooves. In Antrophyopsts, 
on the contrary, the soral lines are practically completely reticu- 
lated, and are entirely superficial. The spores in Euantrophyum 
are triplanate. The spores in Antrophyopsis are diplanate. The 
paraphyses are clavate in Antrophyopsis. In Euantrophyum the 
paraphyses may be either clavate or filiform. The stipe scales 
are of course clathrate in both, but the scale ribs in Euantrophyum 
are smooth; in Antrophyopsis they are verrucose. 
