BENEDICT: GENERA OF THE FERN TRIBE VITTARIEAE 181 
abnormality in the vein unrelated to the real branching plan. 
FIGURES 35-39 are apparently on the same plane, but it is very 
interesting to find in one species that both the free-veined (FIG. 35, 
37) and the areolate (FIG. 36) types may occur. It probably 
indicates, as was suggested earlier, that in the ontogeny of the 
higher genera of the Vittarieae there is not much difference between 
the free-veined Hecistopteris and similar areolate stages. 
In the higher stages, Polytaenium lanceolatum is significant 
as showing the very early predominance of an axial vein. FIGURES 
33, 32, 31, and 30 show successive stages in the venation develop- 
ment. FiGuRE 29 is abnormal. FiGcurREs 30 and 31 are essen- 
tially analogous to the Vittaria intramarginalis stage. No later 
stages were obtained for this species, but these are probably like 
those figured in connection with A th us. 
ANANTHACORUS .ANGUSTIFOLIUS (L.) Und. & Maxon (PLATE 8, 
FIG. 20-23) 
The earliest leaves of this species were not obtained, the 
youngest found being in the Vittaria stage. (See FIG. 23, 24.) 
FIGURES 20 and 21 show, however, how the Polytaenium type of 
venation may be developed from the Vittaria type. As the mature 
venation of A th us is like that of Polytaenium and Anetium, 
it is safe to assume that these genera follow a similar course in 
their ontogeny. 
vy One relationship, already briefly referred to, stands out as 
particularly important, i. e., the homology existing between the 
costal areolae in Polytaenium and the only areolae in Vittaria. 
(Compare FIG. 20-23 with FIG. I1, etc.) The secondary areolae 
in the Polytaenium type arise evidently by the unequal dichotomy 
of the veinlets forming the costal areolae, and as each of these 
usually divides twice, the relation between the size of the successive 
areolae is naturally, as already noted, approximately I : 4:4, 
except as modified by divergence from the midvein. 
ANTROPHYUM RETICULATUM (Schk.) Kaulf. (PLATE 8, FIG. 24-28) 
Perhaps the best evidence as to the generic distinction of 
Antrophyum and Polytaenium is afforded by their ontogeny as 
figured. The earliest stages ef Antrophyum were not obtained 
