570 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
verse, arranged as a deeply and irregularly denticulate border, the teeth bifid. 
Fronds several, 3 to 6 mm. apart, 7 to 14 cm. jong; stipe 4 to 9 cm. long, 0.5 
to 0.7 mm, in diameter, light brownish from a darker base, conspicuously bisul- 
cate anteriorly; lamina deltoid to ovate-deltoid, acuminate, 3.5 to 5 em. long, 
2.5 to 4 cm. broad at the base, pinnatifid to within 1.5 mm. of the elevated, 
usually greenish rachis; segments 5 to 7 pairs, spreading nearly at a right 
angle, very narrowly oblong, the lowermost the largest, 1.8 to 2.2 em. long, 4 to 
5 mm, broad, the upper ones gradually shorter; margins faintly crenate, the 
crenations 2 to 3 mm, long, straight; midveins wholly concealed; veins 7 to 10 
pairs, once or mostly twice forked, the sori terminal upon the first branch; sori 
6 to 9 pairs, large, medial, very prominent; sporangia glabrous, the annulus 
usually 14-celled; spores diplanate, yellowish, granulose. Leaf tissue elastico- 
coriaceous, the segments often tortuous and somewhat involute in drying; 
lower surface distantly but distinctly paleaceous, the scales minute, ovate to 
narrowly ovate-deltoid, long-acuminate to attenuate, 8 to 1.5 mm. long, 0.4 to 
0.6 mm. broad, brown with paler margins, denticulate. 
As already noted, P. pycnocarpum has been very generally misidentified and 
its concept widely extended. Thus, Christensen, in his Index Filicum, gives 
the range “ Mexico-Chile-Argentina ” for this species, The citation of Mexico 
is presumably taken from Fournier,’ who mentions two collections by de Buren 
and Hahn, from the mountains near Jalapa. ‘These plants, which have not been 
examined, are probably referable to P. fallacissinuim, a very distinct species 
which is related rather to P. subvestitum. 
Also, Diels? has published, as Lepicystis macrocarpa (Presl) Diels, a figure 
which very evidently is redrawn from the original illustration of P. tweedianum 
Hook., a species which is extremely different in characters offered by the scales, 
particularly of the rhizome. Notes on P. ftweedianum are given elsewhere.’ 
Further material in this group is greatly needed. The single specimen of 
P. pycnocarpum mentioned above is from the vicinity of Oroya, Peru, altitude 
3,700 meters, Rose 19467. 
13. Polypodium mollendense Maxon, Smiths. Misc. Coll. 65°: 1. 1915. 
TYPE LOCALITY: Low hills near Mollendo, Peru. 
DISTRIBUTION: Known only from the type locality. 
This recently described species is a close ally of P. pycnocarpum and P. 
bryopodum, with which it is contrasted elsewhere. Unlike most of the species 
of this group it is a plant of low altitudes and occurs, so far as now known, 
only near the coast. The following collections have been studied : 
Peru: Low hills near Mollendo, Williams 2978 (type) ; Rose 18989. 
14. Polypodium rusbyi Maxon, sp. nov. 
Rhizome wide-creeping, 10 to 20 cm. long, flattish, rather slender (1 to 2 mm. 
in diameter), deciduously paleaceous, the scales slender, closely appressed, im- 
bricate, narrowly deltoid-lanceolate, long-attenuate, 3 to 4 mm. long, yellowish 
brown, the median portion darker, consisting of narrow cells with reddish 
brown sclerotic partition walls and with mostly distinct lumina, the borders 
equally broad, not very sharply defined, consisting mainly of translucent, oblique 
or transversely linear, minute, thin-walled cells, the margin of the scale irregu- 
larly erose-denticulate. Fronds few, 1 to 3 cm. apart, 15 to 30 cm. long, borne 
upon short broad paleaceous phyllopodia ; stipe 5.5 to 17 cm. long, 0.6 to 0.9 mm. 
thick, stramineous to pale brownish, convex upon the posterior side, bisulcate 
*Mex. PI. Crypt. 83. 1872. 
* Engl. & Prantl, Pflanzenfam, 14: 322. f. 167. C. 1899. 
* Page 574, 
