594 Transactions. 
of the indusium. In the latter species the pinnae are pinnatifid on the 
upper side only, whence the name “ unilaterale,” by which formerly it was 
known. Closely related to this character is the disposition of the sori on 
the upper side of the pinna in a row of from two to four, whereas in 
H. Tunbridgense they normally occur singly at the base of the pinna. Perhaps 
the most important distinction between the two species lies in the fact that 
the margins of the valves of the indusium in H. Tunbridgense are spinulose- 
dentate, but in H. peltatum are quite entire. For the most part these 
the pinnae divided unilaterally, and in one instance with the sori in rows. 
Again, the margin of the indusium in this species is sometimes only slightly 
crenulate. On the other hand, the indusial margin in Н. peltatum is 
occasionally distinctly crenulate instead of being quite entire. Referring 
to Н. peltatum, J. D. Hooker (15, p. 12) says, “ This differs from 
. Tunbri cupressiforme only in the entire lips of the involucre, 
otherwise these plants appear identical. I find the amount of toothing 
in the valves of H. Tunbridgense to vary extremely, sometimes amounting 
to a mere erosion, and at others the lips being even laciniated and 
spinulose, ‚во that І can hardly doubt these two proving eventually the 
same species." 
n the same connection I may note that the specimens of H. minimum 
sent to me by Mr. G. Anderson from Oxford, referred to above, showed in 
most cases the presence, but in others the complete absence, of the most 
important and usually invariable character which separates this species 
from small forms of H. Tunbridgense—namely, the occurrence of spine-like 
teeth on the backs of the valves of the indusium as well as on their margins. 
As mentioned above, the sori in this tiny species are usually borne singly 
on each frond, terminating the main rhachis, but occasionally fronds bear 
two sori. The sorus as a whole is unusually large, and the receptacle some- 
what exserted, approximating in form to that of H. multifidum, so that 
. minimum might conceivably be a much-reduced form of this species. 
J. D. Hooker (14, p. 104) suggests that H. minimum is akin to H. multi- 
fidum, but adds that both the small size of the former and the spinulose 
valves of its involucre afford excellent specific characters. He proceeds: 
“. . . between this plant [i.e., Н. minimum] and Н. caespitosum of the 
Falkland Islands and Cape Horn much analogy exists, especially in size, 
locality, and habit. In each the fronds are generally once divided . · 
both have the indusia free or nearly so, spinulose at the back of the valves, 
and, though often lateral in the latter plant, the fructifications are, especially 
on small specimens, very generally terminal, and may prove to be truly 
же їп Н. minimum should that plant be found in a more t 
ate. 
(Ё) Н. demissum and Н. bivalve. (Plates 63, ТО.) 
Of the New Zealand species of the genus Hymenophyllum these two are 
the most characteristically terrestrial species. Н. demissum occurs t Р 
out Westland from the sea-coast to the stunted upper forest on the ranges 
H. bivalve, in the mixed southern-beech and taxad hilly forests of the Nelson 
Province, and, more especially in its drier and lighter pure southern-beec 
forests, is an exceedingly abundant terrestrial plant along with H. demissum. 
