Igo BOTANICAL GAZETTE [MARCH 
acteristic of the uppermost third, and the mid-height species are 
restricted in these habitats to the sides of prostrate trunks or 
fallen logs. These facts concerning the epiphytic vegetation in — 
general are the key to the local distribution of the Hymenophylla- 
ceae; the most important factors governing their distribution are 
those that have to do with the vertical differences in climate in 
the rain forest. 
The commonest filmy ferns that are invariably rooted in the 
soil on the floor of the forest are Trichomanes rigidum, T. radicans, 
and T. scandens. The first of these has a short erect rootstock 
and its cluster of stiff leaves grows to a height of 20cm. It is 
found on the floor of deep ravines or elsewhere in dense shade, 
and its constant wetness is well attested by the growths of epi- 
phyllous hepatics which cover all but the youngest leaves. T1i- 
chomanes radicans is a climber, sometimes reaching as much as 
2m. from the ground, but only in the most moist situations. Like 
the foregoing species it has finely dissected leaves, the branches 
of which are winged with upturned leaf tissue, providing it with a 
ramifying system of gutters, which happen to serve well in dis- 
tributing over the leaf the chance drops of water which fall from 
overhanging foliage. . 
There are a number of facultative epiphytes with erect leaves 
which either grow in clusters out of an erect rootstock or are spaced 
along a horizontal rhizome. These do not often grow in the sol 
itself, but are commonly found on the ground rooted in tufts of 
moss, on fallen logs, or on the bases of the trunks of trees. These 
forms are slightly tolerant of the drying off of their leaves, but they 
are never found over about 2m. from the ground except in the 
deepest ravines. The habit of the leaves being erect, their wetting 
must take place from rainfall or the dripping of wet foliage; their 
roots, however, are very favorably situated as respects water supply. 
The common members of this category are: H ymeno phyllum 
abruptum, H. ciliatum, H. microcarpum, Trichomanes Hookert, 
T. pyxidiferum, and T. capillaceum. Trichomanes capillaceum om 
the most delicately cut leaves of any of the Jamaican species» 
and its commonest habitat is the bases of the trunks of tree ferns, 
where it is rooted among the coarse rhizoids of the tree fern and 1s 
