73 
specimen was sent to the writer for examination. It is somewhat fragmentary, 
but shows perianths, androecia, and weathered capsules. Unfortunately the 
perichaetial bracteoles are not quite so well developed as might be desired and 
present the appearance of having been aborted in their growth. Except for 
these the specimen agrees in all essential respects with the material from Ari- 
zona and New Mexico. 
The inflorescence of F. mexicana is autoicous, and the species represents the 
seventh autoicous Trachycolea to be reported from the United States, the others, 
being F. Catalinae Evans, F. cobrensis Gotcsche, F. inflata Gottsche, F. Oakesi- 
ana Aust., F. Rappii Evans, and F. saxicola Aust. The plants are mostly 1-2 
cm. long and vary in color from a pale greenish to a purplish brown. They 
grow scattered over the surface of the bark or form very loose tufts. The stems 
are irregularly pinnate and the branches are more or less subdivided, especially 
after the appearance of the sexual organs. 
The leaves are sometimes distant, but are usually more or less imbricated. 
The lobes are somewhat convex, but never squairose, and spread widely, some- 
times almost at a right angle. They are broadly ovate and, on robust leaves, 
attain a length of about 0.75 mm. and a width of 0.6 mm. They are usually 
distinctly cordate at the dorsal base, arching beyond the axis, and are rounded 
at the junction with the keel; the apex is broad and rounded, and the margin is 
practically entire throughout. The lobule is of the type usual in Trachycolea 
and is almost always developed as a water-sac ; rounded above, paiallel along the 
sides, and truncate at the mouth. It lies erect or nearly so at a distance of 
about 0.03 mm. from the axis and measures about 0.35 x 0.3 mm. The inflation 
is often much more distinct in the rounded upper portion and along the outer 
edge, while the two lips at the mouth are often closely appressed. The stylus 
is a subulate process about 0.09 mm. long and 0.03-0.04 mm. wide at the base. 
Measured in cells it is mostly about six cells long and two to four cells wide at the 
base. The cells in the lobe average about 14,11 in diameter along the margin, 
20 jx in the middle, and 24// at the base. Trigones are present everywhere; they 
are usually small and triangular with straight or slightly bulging sides, but the 
latter are sometimes wavy and give the trigones a more irregular outline. Inter- 
mediate thickening are rare near the middle of the lobe, but become more numer- 
ous toward the margin; on the lobules they are everywhere abundant and are 
often more conspicuous than the trigones. 
The underleaves are plane or nearly so and almost always distant, although 
they occasionally overlap toward the tip of a shoot. They are obovate from a 
narrowly cuneate base and measure about 0.4 x 0.27 mm. The apical sinus is 
narrow and about one-fourth the length of the underleaf, while the lobes are 
erect and triangular, with obtuse or acute apices. The lateral margins are entire 
or vaguely sinuate. 
The female inflorescence is borne on a more or less elongated branch and 
usually gives off a robust branch just behind the involucre. The bracts are in 
two 01 three pairs. Those of the innermost pair are complicate, spreading to 
suberect, and unequally bifid. The lobe is ovate to obovate, measuring 0.9-1 
x 0.6-0.65 mm., and the apex is broad and rounded; the lobule is more lanceolate 
