BENEDICT: GENERA OF THE FERN TRIBE VITTARIEAE 169 
Polytaenium Desv., and a revised description is given with P. 
lineatum (Sw.) Kaulf. as the type species. Antrophyum proper 
is typified by an Old World species, A. reticulatum (Forst.) Kaulf. 
The distinguishing feature of Polytaenium, the double or ‘twin- 
net’’ type of venation as compared with the single net type of 
Antrophyum is shown typically in PLATE 6, FIG. I. 
4. POLYTAENIUM Desvaux* 
Type species, Hemionitis lineata Sw. (Type specimen from 
Jamaica.) 
Herbaceous epiphytic ferns with creeping dorsiventral root- 
stocks and fasciculate, simple, entire leaves, the phyllotaxy dis- 
tichous; scales of the rootstock and leaf bases clathrate. 
Leaves glabrous except for a few scales at the base, linear 
to broadly oblanceolate, long-decurrent below; leaf trace double, 
the bundles uniting in the leaf base to form the primary midvein, 
from which branch secondary veinlets to form two or more rows of 
simple areolae along each side. 
Sporangia along the veinlets and sometimes along the midvein 
in lines of indefinite extent, often branching, sometimes reticu- 
late, usually immersed in slight grooves; paraphyses absent; spores 
triplanate (except in one species). 
During the nearly four years since my first paper dealing 
with the species of Polytaenium was published, I have had occasion 
to examine from time to time newly collected herbarium material. 
More recently I have been studying the internal stem characters 
and have made sections of the leaves in order to gain a better 
understanding of their characters. This study has in general 
* Under the title The Genus Antrophyum—I. Synopsis of the subgenera and 
the American species (Bull. Torrey Club 34: 445-458. 19 O 1907), I have already 
given a taxonomic treatment of the species to be included in Polytaentum. At that 
time, basing my descriptions on a careful external study of the plants, I recognized 
nine species. Eight of these should now be named anew as follows: (combinationes 
novae) Polytaenium cayennense (Desv.), Hemionitis cayennensis Desv. Berl. Mag. 
ze, Bot. Zeit. 
6: 702. 1848; Polytaenium anetioides (Christ), Antrophyum anetioides Christ, Bull. 
Herb. Boiss. II. 5: 12. 1905; Polytaenium Dussianum (Benedict), Antrophyum Dus- 
sianum Benedict, Bull. Torrey Club 34: 453- 19 O 1907; Polytaenium Jenmani 
(Benedict), Antrophyum Jenmani Benedict, Bull. Torrey Club 34: 454. 19 O 1907; 
Polytaenium ensiforme (Hook.), Antrophyum ensiforme Hook. in Benth, Pl. Hartweg 
73. FSqt, 
