7f 
in shape, measuring 0.85-0.95 x 0.35-0.45 mm., and the apex is acute or even 
acuminate; just above the middle a slender and sharp-pointed tooth-like lobe 
(stylus) is situated, measuring about 0.16 x 0.06 mm. The bracteole is ovate to 
obovate, about 0.85 mm. long and 0.3 mm. wide, the apical sinus is one-sixth to 
one-fourth its length and varies from acute to rounded, while the divisions are 
mostly acute to acuminate. The bracteole is highly connate with a lobule on 
one side and slightly or not at all connate on the other. The perianth is exserted 
for about half its length and is obovoid in form from a cuneate base. It measures 
1. 2-1. 5 mm. in length and 0.75-0.95 mm. in width. When well developed it 
shows nine or ten folds or keels in the upper part, the two lateral keels, one dorsal 
keel, and two ventral keels being usually higher and more distinctly compressed 
than the others. The short and broad apical beak is entire at the mouth and 
usually lies in a distinct depression formed by the rounded upper extremities of 
the lateral keels, the apical margin of the perianth being consequently obcordate. 
The keels are usually smooth throughout, but are occasionally slightly rough- 
ened by projecting groups of cells. 
The androecia occupy short globose branches, and are usually at some 
little distance from the archegonia, either on a different branch or on the same 
branch. In rare instances the branch just behind the involucre is occupied by 
an androecium. The bracts are closely imbricated and are in only two or three 
pairs; they are subequally bifid with a strongly arched keel; the lobes are rounded 
at the apex while the lobules vary from rounded to subacute. The bracteole, 
which is usually single, is small and bifid. 
The closest relative of F. mexicana is without question F. Rappii Evans, 1 
recently described from material collected at Sanford, Florida, by S. Rapp, and 
known from no other localities at the present time. In fact, if the description 
given above is carefully compared with the description and figures of F. Rappii, 
it will be found that many characteristics are shared by both. For example, 
they are both autoicous; they both have lobes and lobules built up on essentially 
the same plan; their underleaves are very similar; their cell-structure is almost 
identical with respect to the measurements of the cells and the distribution of 
the local thickening in their walls; and their perianths are much the same in form. 
And yet, in spite of these strong resemblances, there are a few slight differences 
which seem to be constant and which apparently warrant a specific separation. 
In F. mexicana the lobes are distinctly cordate at the dorsal base, the lobules 
are only 0.03 mm. from the axis, the divisions of the underleaves are 
never rounded and are usually acute, the lobules of the perichaetial bracts and 
the divisions of the underleaves tend to be lanceolate in outline and acute or 
acuminate at the apex, and the keels of the perianth usually number nine or 
ten. In F. Rappii the lobes are rounded at the dorsal base, the lobules are 
about 0.06 mm. from the axis, the divisions of the underleaves, the lobules of the 
bracts and the divisions of the bracteoles are often broad and rounded at the 
apex, and the keels of the perianth usually number five, although one or two 
low supplementary keels are occasionally present. In F. cobrensis , 2 another 
1 Bryologist 15 : 22. /. i-q. 1912. 
’See Bryologist 16 : 55. 1913- 
