on British Ferns. 
XV 
Genus. — Polystichum, Schott. 
Involucre circular, scale-like, its margins free, attached 
by its centre : first upper pinnule of each pair greatly lar- 
ger than the second, and larger than the first and second 
lower pinnules ; all the ultimate divisions ending in an 
acute spine. 
Obs. — The genus Polystichum, as proposed by Roth, is almost iden- 
tical with Aspidium of Willdenow, but was subsequently restricted by 
Schott to the typical species, and those having a similar circular invo- 
lucre. Although as regards British species the genus thus restricted 
is remarkably distinct, yet among exotic ferns we find species almost 
precisely intermediate between this and the following genus. 
Polystichum angulare. 
Polyp odium aculeatum, Light f. FI. Scot. G75 ; Flucls. FI. 
Ang. 459. 
Aspidium angulare, Willd. Sp. PI. v. 257 ; Sm. E. F. iv. 
291, E. B. S. 2776 ; Mack. FI. Hib. 339 ; Hook, and 
Am. 568. 
Polystichum angulare, Neicm. N. A. 25, F. 173 ; Bab. 412. 
Rhizoma tufted ; stipes one-third as long as the frond, 
densely clothed with large, red, chaffy scales ; frond droop- 
ing, graceful, broad lanceolate, lax, feathery, pinnate; pinnae 
very numerous, linear, distant, pinnate ; pinnules distinct, 
stalked, often distant, auricled at the base, rounded at the 
apex, serrated, sinned. 
Common in woods and shady lanes. 
Polystichum aculeatum. 
Polypodium aculeatum, Linn. Sp. PI. 1552. 
Polypodium lobatum, “ affinis praecedenti (P. angulare, l. c .) 
an distincta sit species ? ” Huds. FI. Ang. 459 ; With. 
Bot. Arr. Veg. 651. 
Polipodium aculeatum, Bolt. Fil. Brit. 48, t. 26. “Polipo- 
dium lobatum, Hall. Hist. 1712, and FI. Ang. 459, is 
doubtless a young plant of Polipodium aculeatum ; of 
this I am certain from observation.” — Bolt. 1. c. 
