90 GYMNOGRAMMOID FERNS [CH. 



(= C. odora Webb & Berth.) an indication of a gradate state. This is probably 

 exceptional for the genus and is not continued, as the flat receptacle would 

 imply. The first segmentation of the sporangium follows the Schizaeoid 

 type (Vol. II, Fig. 455), and the stalk is at first massive and short. 



The prothallus is of the cordate type: its vegetative cells show those 

 collenchymatous swellings of the walls seen in Adiantum, and recurring in 

 the Schizaeaceae. The antheridia have an undivided cap-cell. At first the 

 3'oung sporophyte bears hairs, but later scales are also produced fHorvat, 

 1925). 



Adiantopsis Fee, a genus of shady habit in Brazilian woods, was included 

 in Cheilanthes in the Synopsis Filicum (p. 131), and that is probably its proper 

 place. It is characterised by peculiarly radiating pinnae, readily referable in 

 origin through comparison of the juvenile leaves to a catadromic helicoid 

 branching, as in Matonia: this appears also in Adiantum, Saffordia, and 

 TracJiypteris (Von Goebel, Organographie, II, p. 1046, Fig. 1131). Its round 

 sori with few sporangia are, as in CJieilnnthes, terminal on the veins, each 

 protected by a marginal lappet. 



NOTHOLAENA R. Br. 



This is again a genus of xerophytic Ferns of dry, warm, lands, particularly 

 of Western America and South Africa. The tufted leaves are usually once- 

 pinnate, with free vein-endings, which bear the more or less elongated sori. 

 These consist as a rule of few sporangia, sometimes of a single one, and they 

 are not unfrequently unprotected, or in varying degree covered by the 

 slightly altered leaf-margin. But efficient protection may also be given by 

 hairs and scales which abound on the lower surface of the leaf. The close 

 relation of the genus to CheilantJies is shown by the difficulty in diagnosis 

 of the two genera, and by the frequent synonymy. 



As follows naturally from the closer grouping of the leaves, the stelar 

 structure, though based upon the solenostele, shows the leaf-gaps overlapping, 

 so that the ring is interrupted more than once in the transverse section, as 

 in Pellaea and others (compare Fig. 637). The petiolar trace is as in 

 Pellaea and CheilantJies: thus the anatomy supports the affinity of these 

 genera. 



The sporangia are essentially of the same structure as theirs, with short 

 three-rowed stalks, and an approximately vertical annulus that stops short of 

 the stalk-insertion. There is, however, a high degree of variety in the size 

 and number of the spores. The counts vary from 12 to 64. The largest 

 numbers are made up of the smallest spores, and the smallest of larger 

 spores. They are all of tetrahedral type. Whether or not the difiference in 

 size of these spores is related to heterospory is uncertain in the absence of • 

 culture experiments: but at least the small numbers seen in N. distans R. Br. 



