486 MR. C. B. CLARKE ON THE FERNS OF NORTHERN INDIA. 
by the much smaller ultimate pinnæ. The small forms are known from 4. fontanum | 
and 4. varians by being more compound. 
Subgenus III. Dares. Veins free, simple. Ultimate divisions of the frond linear. 
Involucres linear, dehiscing along the outer edge, not curved nor placed back to 
back, often extending in breadth from the vein to the very margin of the frond. 
26. A. RUT#FOLIUM, Kunze, in Linnea, x. 521. Frond glabrous, narrowly oblong, 
2-pinnate, or sub-2-pinnate ; pinnæ very obtuse.—Mett. Farngatt. Aspl. 110; Hook. 
Sp. Fil. iii. 206; Hk. & Baker, Syn. Fil. 222. A. stans, Kunze, in Linnea, x. 521. 
A. prolongatum, Hook. Sp. Fil. iii. 209, 2nd Cent. Ferns, t. 42; Bedd. Ferns South. 
Ind. t. 138. 
Bhotan and Mishmee, Griffith. Khasia, Simons.—Distrib. Ceylon, South Africa, 
Japan, Fiji. 
Frond 6-12 in., often much smaller than suits the sectional characters in Hk. & Baker; 
glaucous. The North-India examples often have the rhachis prolonged, naked, and 
rooting at the extremity; the ultimate pinne are } in., the sori linear; the fronds are 
2-pinnate, very sparingly 3-pinnatifid or sub-3-pinnate. The examples from North India 
are few, and all alike; but the South-African form a very variable series. 
Subgenus IV. Athyrium. Veinsfree. Involucres linear or aip a young), 
dehiscing along the outer edge, not placed back to back, becoming in age often 
curved or horseshoe-shaped. Scales at the base of the stipe striated long dpi not 
clearly fenestrate. 
‘The involucres are often short, and sometimes so completely recurved that they soon 
become nephrodioid. Thus 4. macrocarpum has been maintained by Moore and others to 
bea Zastrea. To settle the genus, the fruit must be examined quite young to ascertain that 
the short involucre is attached by its edge along the vein and not across it. In other 
cases the involucres are very small and delicate, and the fern is supposed a Davallia. 
In Davallia the sorus should be always terminal on a vein, whereas in Athyrium, 
though the vein appears in some cases to terminate at the sorus, in others on the 
same frond it may be seen to be carried past it. Some Athyriums which have the 
involuere very thin are placed by some authors in Cystopteris; and in some cases it 
is very difficult to say whether the attachment of the evanescent involucre is lateral 
to the vein (Athyrium) or across it (Cystopteris). In other cases, the involucre is ` 
obsolete to such a degree, that Sir W. Hooker has considered Polypodium oxyphyllum, 
Wall., an exinvolucrate var. of Aspidiwm eburneum, Wall.; and Col. Beddome and 
Mr. Baker agree. 
* Rootstock creeping ; stipes solitary, remote. 
27. A. SPINULOSUM, Hk. & Baker, Syn. Fil. 225. Frond 6-12 in., deltoid, as broad as 
long, 3-pinnate; tertiary pinne 1-1 in., oblong, sessile, lobed less than halfway to 
the midrib, spinulose-serrate ; involucres subquadrate, ultimately curved, sometimes ` 
horseshoe-shaped.— Cystopteris spinulosa, Maxim. Prim. Fl. Amur. 340. sii a 
Hookerianum, Moore; Milde, Fil. Burop. e E 
