HorLowavy.—Studies in the New Zealand Hymenophyllaceae. 617 
5. In Westland a large proportion of the species invariably form groups 
according to their habits. ese groups can be recognized also in other 
parts of New Zealand, but differences between the members of the several 
groups are brought to light by their behaviour in lighter types of forest and 
under more variable climatic conditions, which differences are in some cases 
discernible also in their behaviour in the Westland forests. 
6. A progression can be traced in the New Zealand family from species 
which are invariably verredtially-growing to those which are invariably 
ку Дав, and this goes hand in hand with a progressive modification in 
the frond-form, in the relative extent of frond-lamina, and in the thickness 
of the rhizome and stipe, indicating a change from root to frond absorption. 
The species which occupy the most exposed positions both in эч vertical 
and in high altudinal situations, or on exposed rock-faces, do so by means 
e their ability to adopt a stunted imbricated frond-form pn ce with a 
at growth-form. 
T Certain mid-epiphytic species have progressed to a modification of 
the structure of the frond-tissues which undoubtedly aids them in retaining 
this station. Of these Н. Malingii is the most notable example. It is sug- 
gested—and reasons are given—that the multi-layered condition of the 
frond-lamina in H. dilatatum, Н. scabrum, and T. reniforme is an acquired 
and not a primitive character. 
he species of Trichomanes are far more restricted in their distribu- 
tion and in the ability to modify the frond-form than are those of Hymeno- 
phyllum, the only exception to this being T. reniforme, which in Westland 
is a characteristic mid-epiphyte, and which possesses a peculiar but fixed 
form of frond, and along with it the ability to inroll the frond closely. 
9. The smaller species, both of Trichomanes and of Hymenophyllum, 
commonly adopt the mat growth-form even in their low epiphytic stations, 
this being especially marked in those of the former genus. 
Four pairs of closely related species may be distinguished in the 
New Zealand family—viz., H. sanguinolentum and Н. villosum; Н. australe 
and H. atrovirens ; H. flabellatum and H. rufescens ; H. Tun bridgense and 
Н. peltatum. From the fact that in the case of each of these pairs the two 
members are more or less complementary in their altitudinal distribution, 
and also that intermediate forms are to be found at intermediate altitudes, 
it would seem that one member in each pair is a derived and possibly a 
mountain form of the other. The eec existence of the two members 
side by side in the case of at least three of these four pairs, under apparently 
identical environmental conditions, makes more difficult the understanding 
of the exact relation of the two members to each other. - 
11. The suggestion has been put forward that in view of the fact that 
the greatest modification of the existing family so far as the New Zealand 
species are concerned, apart from the probable reduction in size of many 
species, has been in the direction of the adoption of the epiphytic habit 
with the tendency towards dependence upon frond absorption rather than 
upon root absorption, that therefore the more primitive growth-form and 
frond-form and stem-anatomy is to be looked for in the typically terrestrial 
members of the family, and possibly in the tufted species, rather than in 
any of the other members. 
. It is suggested that the inability of the larger epiphytic species to 
adopt to any noticeable extent in the lowland forests of Westland the 
terrestrial or low epiphytic station may be due to the need in the dark 
forest-interior of seeking the maximum illumination possible. Possibly 
this explains the fact that in Westland T. venosum and H. ferrugineum 
