ACOTYLRDONS. FTLiCES. Hymcnophyltum. 157 



HAR. Woods, heaths, and rough stony soils, abundant. 



Used 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, Lightf. 



8. BLECHNUM. 



Sori linear, longitudinal, continuous, parallel on eacli side of the rib 

 of the frond. Involucre superficial, continuous, opening inte- 

 riorly. 



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

 rather obtuse parallel, fructiferous fronds pinnate, pinnae linear 

 acuminate. E. #. /. 1 159. Osmunda spicaiil, Ligktf.p.654+ 



HAD. Woods, heaths, among rocks, c., plentiful. 



9. ADIANTUM. 

 Sori oblong or roundish* Involucres membranaceous, arising 



from distinct portions of the margin of the frond turned in, 



opening interiorly. 

 1. A. Capillus VencriSy frond bipinnate, pinnules obovato-cuneate 



inciso-sublobate, segments of the fertile pinnules terminated 



by a linear-oblong sorus, sterile ones serrated. K. B. t. 156-J. 

 HAD. Banks of the Carron, a rivulet in Kincardineshire, Prof. Beattie. 



10. HYMENOPHYLLUM. 



Sori marginal. Capsules sessile, inserted upon a common cylin- 

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

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



1. H. tunlridgense, fronds bipinnatifid glabrous, the segments 



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

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

 but instead of being flat it curls inwards, 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 which 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 tins or- 

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

 the forming a new genus. I have found it in Pteris candata, which is very 

 nearly allied to aqitallna : it also occurs in Pt. esculenta : and our mutual 

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

 genus Pteris, 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 involucmm 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 Invohtcntm" Smith in 

 Letter, Aits- 1B19. 



