584 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
centered scales similar in structure to those of the rhizome, but more deeply 
fimbriate, mostly roundish, 0.4 or 0.5 mm. broad, sometimes deltoid, long-acumi- 
nate, and nearly 1 mm. long; scales of the upper surface minute, whitish, sub- 
stellate, the divisions spreading and unequal. 
Type in the U. 8S. National Herbarium, no. 574354, collected near Pantepec, 
Chiapas, Mexico, altitude 1,540 meters, January 16, 1907, by G. N. Collins and 
C. B. Doyle (no. 227). The specimen consists of two complete fronds attached 
to portions of the rhizome. 
Polypodium collinsii has no especially close allies. The characters offered by 
its smooth, sinuous rhizomes, closely appressed, minute, peltate rhizome scales, 
and very minute, roundish scales of the under side of the lamina suggest a 
relationship with P. myriolepis; but it differs from P. myriolepis wholly in 
gross morphology. The scales of: the under side of the lamina are numerous, 
but so far apart that the yellowish green leaf surface is not obscured. In di- 
mensions and leaf shape only P. collinsii recalls P. lepidotrichum; but that is a 
species with subfasciculate fronds and very long, nearly capillary, ferruginous 
rhizome scales, and witb at least part of the imbricate or contiguous scales of 
the lower side of the lamina long-aristate from a rounded base. 
EXPLANATION OF PLATE 41.—The larger of the two type fronds of Polypodium collinsii, 
Scale 3. 
4. Polypodium macrolepis Maxon, sp. nov. 
Rhizome epiphytic, wide-creeping, sinuous, with a few short or elongate 
branches, radicose at intervals (the rootlets brownish-tomentose, freely 
branched), 3 to 5 mm. in diameter, flattish in drying, very firm, densely covered 
with straight, elongate, widely imbricate scales, these 3 to 4 mm, long, 0.65 to 
0.85 mm. broad, narrowly deltoid-oblong, long-attenuate to a subflexuous tip, 
bicolorous, the broad median portion castaneous, the cells of the basal part 
mostly short, hexagonal, thick-walled, with closed or concealed lumina, those 
of the middle and apical part gradually longer and paler, at length narrowly 
linear and acute; borders pale, the cells in many rows, mostly linear, indistinct; 
margins deeply denticulate, the teeth bifid, variously curved. Fronds distant, 
rigid, ascending or erect, 20 to 40 cm. long, the stipe much shorter than the 
iamina; stipe 4 to 10 cm. long, 1 to 2 mm. thick, flattish, often tortuous, smooth, 
closely paleaceous, the scales mostly like those of the lower side of the lamina ; 
lamina 13 to 28 em. long, 5 to 9 em. broad, oblong to lanceolate-oblong, not or 
searcely reduced at the base, here fully pinnate, nearly so throughout, long- 
caudate, the apical pinnew long, abruptly discontinuous; rachis stout, paleaceous 
beneath like the stipe; pinnz 15 to 20 pairs, slightly ascending, 3 to 5 cm. long, 
4to6 (7) mm. broad, linear to linear-lanceolate, acute or mostly long-acuminate, 
entire, the 2 or 3 lower pairs distant, broadly excavate to the midrib below, 
slightly constricted above; middle pinnz closer, more oblique, fully adnate, 
slightly decurrent, faintly joined, the sinuses obtuse or broadly acutish; midveins 
not elevated above, slightly so beneath; veins oblique, deeply immersed, atypi- 
cally goniophlebioid, a row of elongate-oval areoles extending nearly to the mar- 
gin, bordered by an incomplete second row of small alternate areoles, the latter 
without included veins, a few veinlets excurrent; sori 5 to 9 pairs, 1.5 to 2.5 
mm. in diameter, round to oval, not contiguous, medial, impressed (the upper 
surface distinctly mamillose), terminal upon the very oblique, usually simple, 
single, included veinlet of the areoles; sporangia glabrous, the annulus usually 
18-celled ; spores diplanate, granulose. Leaf tissue rigidly spongiose-herbaceous, 
dull green above, bearing numerous small distant peltate scales, these roundish 
or deltoid-acuminate, with minute brownish centers, the broad white borders 
fimbriate-denticulate; under surface closely paleaceous, the scales mostly con- 
