152 



BOTH S FEEX. 



middle figure at page 14 0. The frond is pinnate : the pinnae 

 are nearly oj)posite, and, as we have seen hj the admeasure- 

 ments, the pairs gi'adually approximate from the base towards 

 the apex : the first and second pairs are verj^ broad at the base, 

 in some instances nearly triangular ; the third is longer and 

 narrower ; the fourth, fifth, and sixth still longer and narrower, 

 and also more linear, the sides being nearly parallel : all the 

 pinnae are pinnate, except those quite at the apex of the frond : 

 the pinnules are distinctly separate, and almost stalked ; those 

 of the ujjper pinnae are connected by an extremely slender wing 

 of the midrib of the pinna, but this wing is not to be distin- 

 guished on the lower pinnae, except near the point ; the pin- 

 nules of the lower pinnae are pinnate, those on the middle are 

 pinnatifid, and on the upper deeply lobed : aU the divisions are 

 serrated, and each terminates in a short but distinct spme. In 

 the first, second, and third pairs of pinnae, the inferior pinnules 

 are generally longer than the superior ; the first, second, and 

 third inferior pinnules of the first pair of pinnae are almost 

 invariably longer and altogether larger than those which suc- 

 ceed them ; the diminution of the rest in size is sometimes 

 very abrupt, sometimes gradual. 



Every lateral vein supplies one lobe or division of a pinnule ; 

 it is always branched, and almost every anterior branch bears 

 a cluster of capsules : these are scattered generally over the 

 frond, without any definite arrangement : they are covered by a 

 very irregular but somewhat reniform involucre, the margins of 

 which are uneven, and more or less fringed with stalked trans- 

 parent glands. These are described as characteristic of As- 

 pidium spinulosum by Swartz, Willdenow, and Fries ; and the 

 present plant is thus identified with the A. spinulosum of those 

 authors. 



Varieties. 



This is usually stated to be a very variable fern ; but the 

 degree of variation will, I imagine, be found very much to de- 

 pend on the number of species included under one name. I 

 do not wish to moot the subtle question of "what is a species ? " 

 but I think it is convenierit to assign a name to every object 



