MAXON—STUDIES OF TROPICAL AMERICAN FERNS. 
Pinne denticulate to crenate-serrate upon the upper 
margin; fronds less numerous, the stipes usually 
stouter, castaneous. 
Scales of the rhizome brownish to blackish, often 
iridescent. . .-..-.------ eee eee eee eee e ee eeee 
Scales of the rhizome light ferruginous .........-. 
Sori borne mainly in pairs, i. e. those of the distal and 
proximal sides nearly equal in number. 
Fertile veins (some or all, exclusive of the basal ones) 
forked. 
Lamina 5 to 9 cm. broad; pinne relatively few. 
Pinnz 10 to 20 pairs, all but the basal ones nar- 
rowly oblong from an acute or subrectangu- 
lar inequilateral base, obtuse......-------- 
Pinne 7 or 8 pairs, much larger, distant, strongly 
deltoid from a broadly cuneate inequilat- 
eral base, acute .........--------e eee eens 
Lamina 1 to 3 (rarely 4) cm. broad; pinne 
numerous. 
Pinne deeply crenate-serrate or incised; rhizome 
scales yellowish brown, with a heavy dark 
median stripe. ...-.-...--e- eee cece eeeeee 
Pinne subentire to crenate; rhizome scales dark 
brown or blackish. 
Sori short, borne near the margin; scales with 
long capillary apices......------ 
Sori relatively longer, nearer the midvein 
than the margin; scales merely long- 
attenuate. 
Stipes and rachises conspicuously alate, 
more or less fibrillose; fronds few; 
pinne subrectangular-oblong; veins of 
the proximal side simple......--------- 
Stipes and rachises faintly alate, not 
fibrillose; fronds very numerous; pinnse 
oval to oval-oblong; veins of both sides 
usually forked........-..-.---++--+--+- 
Fertile veins (the distal basal ones excepted) usually 
simple. 
Scales of the rhizome light ferruginous- -......-.-- 
Scales of the rhizome brown to blackish. 
Sori confined to the lobes of the pinne.......--- 
Sori not borne upon the lobes. 
Stipes and rachises black or blackish. 
Pinne broadly crenate; stipes and rachises 
very slender, minutely alate.......... 
Pinne sharply crenate-dentate; stipes and 
rachises stouter, conspicuously alate.... 
Stipes and rachises castaneous or distinctly 
brown. 
Rhizomes short; fronds closely fasciculate, 
ascending or rosulate, strongly arcu- 
A es 
eee eee eee 
17. 
16. 
18. 
19. 
14. 
16. 
7. 
137 
. monanthes. 
. denudatum. 
. melanorachis. 
. kellermanit. 
. carolinum. 
. resiliens. 
. nesioticum. 
. trichomanes. 
. denundatum. 
. pringler. 
underwoodii. 
. heterochroum. 
. vespertinum. 
