THE JAMAICAN FiuMy FERNS 67 
a splendid development in number of species and wealth 
of individuals. The exacting moisture requirements of 
these plants are met in the shady floor of the lowland 
forests, while in the rainy fog-filled forests of the moun- 
tains the moisture is great enough to permit filmy 
ferns to grow above the floor of the forest both as climbers 
and as epiphytes. Among the Jamaican Hymenophyl- 
laceae we find a diversity of habit, structure and habitat, 
in spite of the specialized character of the group. A 
set of 26 species communicated to the writer by Prof. 
Giesenhagen, from Ceylon and Java, show no such 
structural variety, and give no hint of such diversity 
of habitat as do the Jamaican plants under considera- 
tion. Forty-nine species of filmy ferns have been de- 
scribed from Jamaican material, but some of these are 
extremely rare, while others are of doubtful validity. 
The writer was able to find only 33 species, 18 of Trich- 
omanes and 15 of Hymenophyllum. 
At the lowest elevations filmy ferns are to be sought 
on shaded rocks near waterfalls and on the trunks of 
trees near the ground in deep shade. Most of the forms 
found below 2000 feet have very small and relatively 
simple fronds. One of the simplest of these is Trich- 
omanes sphenoides, which has nearly circular sessile 
fronds, seldom exceeding 14 inch in diameter. Trich- 
omanes reptans, T. polypodioides, and T. pusillum belong 
to this simple type, while 7. muscoidewm has longer 
fronds, simple or pinnatifid, resembling those of our 
own T. petersii of Georgia and Alabama. 
A very common type of Trichomanes, which is closely 
like several species of Hymenophyllum, may convenl- 
ently be alluded to as the “generalized type.” It has 
bipinnate, stipitate, glabrous fronds, in which the ulti- 
Mate segments are of a uniform width of about one- 
Sixteenth of an inch. This type is erect in growth, 
may be terrestrial or epiphytic, and has fronds from 
