ACOTYLEDONS. — FILICES. Hynrcriophylhim . ].">7 



IIab. Woods, heaths, and rougli stony soils, abundant. 



lised as litter for cattle, and very frequently for the purpose of 

 thatching cottages. The ashes are employed in the manufactories 

 of soap and glass. Its astringent quality has recommended it in 

 the dressing and preparing kid and chamois leather • the country 

 people take it medicinally, to destroy worms, and a bed made of 

 the green plant is esteemed a sovereign cure for the rickets in 

 children, hi^htf. 



8. BLECHNUM. 



Sor'i linear, longitudinal, continuous, parallel on each side of tiie rib 

 of the frond, /«t'o/?/cre superncial, continuous, opening inte- 

 riorly. 



1. Bl. horeale, sterile fronds pinnatifid, the segments lanceolate 

 rather obtuse parallel, fructiferous fronds pinnate, pinnre linf^ar 

 acuminate. E. B. t. 1159. Osmunda spica?ity IJghtJ'.p,{j5-i. 



IIab. Woods, heatks, among rocks, &c., plentifid. 



Q. ADIANTUM. 

 .9071 oblong or roundish. Involucres membranaceous, arising 



from distinct portions of the m.argin of the frond turned in, 



o})ening interiorly. 

 1. A. CapiU'u^ VevcrU, frond bipinnatc, pinnules ol>ovato-cuneate 



inciso-sublobate, segments of the fertile pinnules terminated 



by a linear-oblong sorus, sterile ones serrated. E. B. t. 15G4. 

 ILvB. Banks of the Carron, a rivulet in Kinoardinesliire, Prof. Ecattle. 



10. HYMENOPHYLLUM. 



Sori marginal. Capstdes sessile, inserted upon a common cvliu- 

 drieal receptacle, within a 2-valved involucre of the same tex- 

 ture as the frond ; valves plane, exterior one free. Br, 



i. H. tunbridgense, fronds bipinnatifid glabrous, the segments 



between the two, the line of capsules is placed. It may be called the inner 

 mvolucre, and much resembles the outer, having, like that, a ciliated edge; 

 but instead of being tlat it curls inward3, covering the capsules in their 

 young state, and being itself covered by the outer one. It is best perhaps 

 seen when the capsules are about half ripe : at whicli time it is nearly of 

 the same breadth as the outer one, and is readily seen by the assistance of 

 the microscope. In texture it seems to differ a little from the outer." 



" According to the principles upon which genera are formed in this or- 

 der, the inner Involucrum seems to afford a character which would justify 

 the forming a new genus. I have found it in Pter'is caudata, which is very 

 nearly allied to aqualina : it also occurs in Pt. esculcnta : and our mutual 

 friend -jirown authorizes me to say that it is found in a small group of the 

 genus Pterh, the species of which agree in habit and are mostly extra- 

 tropical, differing from the tropical species in having a thicker and harder 

 frond, and not a thin filmy one which is found in most of the latter. It is 

 perhaps not unworthy of remark, that this involucnim is never found, except 

 when there is fructification. The outer one, it is well known, is almost al- 

 ways present whether there is fructification or not, — a circumstance, I be- 

 lieve, which does not generally take place in a true Involucrum." S7riitk in 

 Letter, Atig. 1819. 



