ftd COM^niX BRAKES. 



is a bleached semihyaline membrane, fringed with a series of 

 jointed capillary segments. Beneath this membrane are the 

 capsules, also attached to the marginal vein, and arranged along 

 it in a continuous linear series, but more abundantly at its 

 points of union with the transverse veins. Again, beneath this 

 linear series of capsules, is a second bleached and fringed mem- 

 brane, very similar to the first. It becomes an interesting ques- 

 tion, whether both these membranes can be considered analo- 

 gous to the usual involucre, or one of them only ; and if one 

 only, then which are we to select ? Eoth (Flor. Germ. iii. 12) 

 does not appear to have observed the inferior membrane, but 

 describes the superior one as an involucre originating in an 

 elongated epidermis. Sir J. E. Smith, although aware of this 

 inner membrane, unhesitatingly speaks of the outer one as the 

 "cover," (Eng. Flor. iv. 304). Mr. Wilson, who has most obli- 

 gingly favoured me with many valuable observations on this 

 remarkable structure, seems to regard the inferior membrane 

 as the involucre ; the occasional presence of the superior mem- 

 brane in the total absence of capsules, proving, in his opinion, 

 that it is not necessarily connected with fructification. Still, 

 although I may state that I do not detect its presence in seed- 

 ling or barren plants, and am therefore led in a measure to as- 

 sociate its appearance at least ivith the power of producing fruit, 

 yet I am quite inclined to consider it distinct from a true invo- 

 lucre, and more analogous to the inflexed portion of the pinnule 

 in Adiantum and Allosorus, which I have always regarded as 

 perfectly distinct, although considered an involucre by Sir J. 

 E. Smith, and all our more eminent authorities ; and although 

 there can be no question that its presence is connected with 

 fructification, since, in both these genera, it is absent when the 

 frond or pinnule is entirely barren : instances, however, occur 

 in all the genera above cited, in which this inflexed or folded 

 margin of the pinnule is totally unaccompanied by the pre- 

 sence of capsules, as pointed out to me in Eupteris by Mr. W. 

 Wilson. Mr. Jenner, who has most obligingly taken the great- 

 est pains to assist me in the inquiry, as regards Eupteris, also 

 appears to consider the exterior membrane as nothing more 

 than a prolongation of the outer epidermis. The question, as 

 regards the interior membrane, seems much more restricted. 

 We are compelled to regard this as an involucre, from tlie 



