MAXON—STUDIES OF TROPICAL AMERICAN FERNS. 571 
upon the anterior side, narrowly marginate at the apex; lamina 10 to 18 cm. 
long, 5 to 8 cm. broad at the base, narrowly deltoid, subpinnatisect throughout, 
the pinne successively shorter toward the conspicuously long-caudate apex (this 
2 to 4 em. long, 3 to 7 mm. broad), the yellowish rachis narrowly foliaceo-mar- 
ginate in the lower part, more broadly so toward the apex; segments 10 to 12 
pairs, horizontal (or the lower ones deflexed), 1 to 3 times their width apart, 
mostly linear, the basal ones 2 to 4 cm. long, 4 to 7 mm. broad, acutish, surcur- 
rent, excavate nearly to the midvein upon the proximal side; middle segments 
similar but slightly shorter, subequally dilatate and joined by a narrow wing; 
apical segments about 1 cm. long, or less; margins slightly cartilaginous, slightly 
undulate, distantly appressed-serrulate; veins 8 to 13 pairs, partially concealed, 
mostly twice forked, the large sorus usually terminal upon the proximal 
branch; sori 7 to 12 pairs, nearly medial. Leaf tissue grayish green, membrano- 
herbaceous, glabrous and nonpaleaceous above, beneath bearing numerous scat 
tered scales, these small but easily visible to the naked eye, 1 to 1.5 mm. long, 
narrowly deltoid, sometimes long-acuminate, attached above the rounded base, 
brownish, darker in the median part (the cells rather short, quadrate or poly- 
hedral, with reddish brown sclerotic partition walls and large lumina), the 
paler borders composed of 1 or 2 rows of transversely oblong thin-walled cells, 
the margin rather conspicuously erose-centiculate. 
Type in the U. 8. National Herbarium, no. 50934, collected in the vicinity of 
Yungas, Bolivia, altitude about 1,800 meters, 1885, by H. H. Rusby (no. 353) ; 
distributed as Polypodium plebejum Schlecht. & Cham. 
The following additional material, all in the National Herbarium, has been 
studied : 
Bouivia: A second sheet of the type collection, Rusby-353. Sorataé, alt. 
3,000 meters, February, 1886, Rusby 352 (2 sheets). Without precise 
locality, Bang 2592. 
The rhizome scales of P. rusbyi are slender, closely appressed, and neither 
crispate nor fuscous-carinate, and so indicate very clearly that this species is 
not a near relative of P. plebejum. They do, however, suggest a relationship 
with P. typicum and P. murorum. With the first of these P. rusbyi is not 
likely to be confused, on account of the much greater size of all its. parts. 
From the latter it is easily distinguished by its fully adnate segments, more 
delicate texture, and the fewer, smaller, paler, and more distant scales of the 
under surface. 
As mentioned on page 575, this plant, as represented by Rusby’s 352 and 
3538, is included by Hieronymus under P. tweedianum, a disposition which to 
the writer seems certainly erroneous. 
15. Polypodium murorum Hook. Icon. Pl. 1: pl. 70. 1837. 
Polypodium sporadolepis var. 8 Mett. Abh, Senckenb. Ges. Frankfurt 2: 67. 
1856. 
TYPE LOCALITY: Vicinity of Quito, Ecuador (Jameson 49). 
Distripvtion : Costa Rica, Colombia, and Ecuador, ascending to 3,400 meters. 
ILLUSTRATION : Hook. op. cit. pl. 70. 
Available material of this species is not complete enough to admit of more 
than temporary treatment. Jameson’s original specimens, which are exceedingly 
fertile and appear to have grown in the open, are matched by several plants 
of his collecting in the National Herbarium. They represent an extreme form 
which is deeply bipinnatifid. Most other Ecuador specimens at hand have the 
pinne subentire, an apparently intermediate state being Rosenstock’s no. 1a. 
There is great variation also in the scaly covering of the under side, the con- 
gested plants of Jameson having a dense imbricate covering, while larger and 
