310 DESCRIPTION OF A NEW FERN FROM MALACCA, 
veins forming small, nearly uniform, square areole, within which are 
the ultimate, much divaricating, and free veinlets, bearing the sori: 
in our plant there is only one primary stout vein or central costa, and 
from each side of that more than half the space between it and the 
margin is occupied by a series of large subhexagonal areoles, formed 
by slender secondary veins, within which alone are the very divaricating 
and ultimate free, or soriferous, veinlets; and between these and the 
margin are lesser areoles in one or two irregular series, including their 
veinlets, always free from sori. Thus in our plant, the sori being con- 
fined to the costal primary areoles, they form a pretty regular single 
series on each side the midrib, whereas in P. Horsfieldii and W'allichii 
the sori are widely diffused in the more uniform secondary areoles. 
In constituting the genus Dipteris (D. conjugata, Reinw., Polypo- 
dium [Dipteris] Horsfieldii, Br.), Dr. Reinwardt seems to have been 
guided more by habit than by essential character; for his only descrip- 
tion of the genus is ** Capsule in disco frondis sparsze, solitarie aut con- 
ferte. Indusium nullum.”—M. Fée, who, as far as I know, is the only 
author besides Reinwardt that upholds Dipteris as a genus, says, “ Il est 
facile de reconnaître ce genre à ses nervures primaires flabelliformes et à 
l'absence du mésoneure. La fronde est profondément divisée en deux 
parties, qui tendent à s'appliquer l'une contre l'autre par leur lame su- 
périeure.” Strange to say, he seems to be acquainted with only one 
species, and makes the Polypodium Wallichii a synonym of the Dipteris 
conjugata of Reinwardt (Pol. Horsfieldii, Br.). Mr. Brown gives the 
following excellent character of the “ subgenus” (of Polypodium) ** Dip- 
teris :—Sori subrotundi, sparsi (v. transversim subseriati) inter (frondis 
palmatz) venas primarias diehotomas earumque divisiones, venulis di- 
varicatissimis anastomosantibus insidentes. — Zndusium (verum) nullum. 
—Caudex repens, teres. Frondes elongato-stipitate, binate ; partiales 
dimidiate, palmato-lobate. Venule secunde tertiarie et ultime divari- 
catissime, crebre anastomosantes, penultime latere sorifere, ultima apice 
_ viz dilatato libero. Indusium spurium, vel (in D. Horsfieldii) pile sorum 
cingentes et capsulis intermixti ; vel (in D. Wallichii) materia pulposo- 
grumosa capsulas immaturas obtegens.” 
Even the dinate character (whence the name) of Dipteris is not ap- 
parent in our plant, for the primary furcation does not divide the frond 
into two equal portions: the Whole frond is a series of deep dichoto- 
mies digitate rather than palmate. If there are characters to distin- 
