11 257 



several species of the group of D. fiUx mas, is found only in D. tablaziensis. Only 

 in quite few species does the coating of scales extend along the whole length of the 

 stem, in fewer the rachis is also scaly, and linally there is a few species having 

 scales on the underside of the leaf (D. velata, D. Funckii, D. Rosenstockii). 



The density of the hairiness of the leaf is very variable, as naturally expec- 

 ted, but on the other hand its kind is a good specific character, which is used to 

 a considerable degree in the key below. Q)uite glabrous species scarcely exist, as 

 there are nearly always hairs on the midrib of the pinnæ above, but there are some 

 species, which apart from these are, practically speaking, glabrous throughout. The 

 kinds of hairs which occur, may generally be referred to three types: (1) very 

 short hairs, often only visible under a strong magnifying glass and with hook- 

 shaped points (pili hamati), (2) long, mostly whitish or yellowish, soft hairs, and 

 (3) stiff bristles (setæ). As a fourth kind may here be mentioned the stellate hairs, 

 which are found in the two species D. Canadasii and D. Stiibelii. 



In numerous species a marked difference in the pubescence of the under- and 

 the upperside is found especially on the costæ, which are generally setose above 

 with stiff, forward pointing, subappressed hairs, beneath (but not in all species) 

 with soft, whitish, patent hairs. Some species are furnished on the upperside along 

 the veins with solitary, stiff setæ (D. cohimbiana, D. corazonensis, and others), others 

 have only pili hamati (e. g. D. concinna), others again all three kinds and then 

 they have pili hamati on the parenchyma between the veins, while these and the 

 midribs are furnished with long hairs. The most differentiated pubescence is 

 found in D. corazonensis. In order to convince oneself of the kind of the pubes- 

 cence of a species one must in most cases make use of the microscope. 



The texture of the leaf varies considerably and is partly dependent on outer 

 factors and the age of the leaf and is therefore not of great value as a mark of 

 the species excepting the extreme forms : the very thin, almost transparent leaf 

 and the rigid, coriaceous or chartaceous leaf. 



The position on the vein of the sori is very constant within the species, 

 therefore of great importance. More variable is their shape, of which I have 

 spoken above; not rarely the sori — especially the basal ones — show as they 

 grow old a tendency to elongation. Their equipment with an indusium should be 

 a constant character, which, however, as already mentioned, is rather difficult to 

 use within this group, most species of which have only a very small, early falling 

 indusium. This is rarely quite glabrous, often glandulose and in many species more 

 or less setose. In some species, as D. Sprengelii, D. pachyrachis, the indusium is not 

 quite reniform as is otherwise the case in Eudryopteris, but oval, a peculiarity which 

 induced Fée to mark off the species showing this as a separate group Oochlamys. 



Most species have glabrous, short-stalked sporangia. Only in three (D. concinna, 

 D. Stierii, D. firma) are the sporangia furnished with some few setæ, which I have, 

 however, recognized in all the numerous specimens examined, whereas in no other 

 species have I ever found a setose sporangia. 



34* 



