Bower . — Shidies in the Phytogeny of the Filicales. VI. 3 
subjects of comparison materially helps. Since the time of writing the 
previous memoirs, I have received from Mr. Cave of Darjeeling, through 
the kindness of the Director of the Calcutta Garden, a supply of a Fern 
at present known as Leptochilus tricuspis , which has been closely related by 
the older systematists with Cheiropleuria . While examining its anatomy 
for the first time, opportunity has been taken to investigate certain other 
Ferns also, with a view to testing relationships. This may help to trace the 
probable affinities of these relatively isolated, but apparently kindred forms. 
All of them have superficial sori, without indusia ; and accordingly they 
may be expected to show some degree of relationship downwards to 
a Dipterid-Matonioid, and finally a Gleichenioid source. On the other 
hand, Sir William Hooker had already suggested for Gymnopteris (the 
genus to which he referred Leptochilus tricuspis ) a relationship with Polypo- 
dium} Speaking of the Gymnopteris section of Acrostichum , he remarks : 
‘ This corresponds in venation and a good deal in habit with Phymatodes 
among Polypodieae.’ Thus further inquiry may tend to substantiate 
affinities in more than one direction. 
The Fern now styled Leptochilus tricuspis (Hook.), C. Chr , has under- 
gone several synonyms, and has been placed in different systematic relations 
by various writers. It was first described by Sir William Hooker, from 
specimens collected by Mrs. Atkinson in hot valleys of Sikkim-Himalaya, 
under the name of Acrostichum ( Gymnopteris ) tricuspe , Hook. He placed it 
next to Acrostichum ( Gymnopteris) bicuspe , Hook. — now called Cheiropleuria 
bicuspis (Bl.), Presl — and he remarks of it that ‘ this very fine and new 
species, with not a little of the habit and venulation of A . bicuspe , differs 
remarkably in being trilobed or tripartite, and it has always a solitary 
central costa to each lobe ’. 2 It will be seen that, notwithstanding these 
and other points of difference, its true relation is that indicated by Sir 
William Hooker : while it serves, as also does Cheiropleuria , as a synthetic 
link between forms often placed apart in the systematic arrangements 
of various writers. 
John Smith 3 followed Hooker in placing it in close relation to Cheiro- 
pleuria bicuspis (Hook.) and C. vesper tilio (Hook.), and he remarks : ‘It 
is probable that the above three species are different forms of one only.’ 
This is a position which it will be impossible to maintain. 
On the other hand, Diels 4 places the Fern which he names Gymnopteris 
tricuspis (Hook.), Bedd., far away from Cheiropleuria in his system (p. 336), 
and gives no reference of relationship between them. He does, however, 
compare the latter with the Pleopeltis section of P olypodium : and this line 
of comparison will be seen to be materially strengthened by the facts 
relating to Leptochilus tricuspis to be detailed below. Christ also separates 
1 Hooker : Sp. Fil. v, p. 270. 2 Species Filicum, vol. v, p. 272, Tab. CCCIV. 
3 History of Ferns, 1875, p. 139. 4 Engler und Pranll, i, 4, p. 199. 
