FOLVrODIACEA'. 329 



hereditary" rathcr tbau posterior, and are subject to the least chauge iu the 

 coiu^se of the phylogenical clevelopment of species. It is, therefore, one of the 

 most reliahle characters for the determination of tlie kiiishij) of geuera. 



Let me now briefly state liow far Prosaptia agrees with Davallia in 

 respect of its vegetative oi-gans. The rhizomes of the latter are loug-creepiug 

 with remotely an-anged fronds, while those of the former are short-creeping 

 with densely arrauged frouds. The scales of Davallia are comjjosed of celLs 

 with very thin reddish walls aiTanged iu one layer with uo trace of bristles, 

 and are totally differeut from what we have ohserved in Prosaptia or Poly- 

 podium ohliquatum. The hairy stipes so peculiar to the latter two have never 

 been fouud in DavalUa. »So far as the vegetative organs are conccrucd, 

 Prosaptia is not congeneric wdth Davallia. 



Now let me consider more iirecisely a comparisou of the samc ferus iu 

 respect of their fructifieatiou. 3Iy ojuuion is that thc fructificatiou of Prosap- 

 tia is altogether the sanie as that of Polypodium iu its origin, but totally 

 differeut from that of Davallia iu its begiuniug, as I shall show latcr ou. 

 Bcfore I go into details, I must pause to consider wliat tlie fructiticatiou of 

 Polypodium obliquatum or of its allied species is like. In the fuU growu 

 form, the sori (Fig. 137, g) of this feru look very differeut from the ordinary 

 sori of a normal Polypodium. Therefore, it was regarded by Fee as repre- 

 senting the special geniis, Cryptosorus-^. The sorus is located iu a pouch-likc 

 cavity immei-sed in the tissue of the frouds on the under surface, wliich cavity 

 has an oi-ilicc beset with bristl&«. Accordiug tij the author, the sori develop iu 

 the foUowiug manuer : they are iu the bcginuiug fi)rmed luider thc epidermis 

 (" cuticule ") from which, wheu fully develoiied, at leugth break out ; the slits 

 in the siiidermis are the orifices of the i)ouch-like cavities. lu order to assm^e 

 myself of wliat is stated by Fee, I looked iu my very rich collections of the 

 same fern, and was so fortimate as to find that tlic feru is of a nature of 

 indefinite growth, representing aeveral stages of the soras-devclo2imcnt iu one 

 and the same frond. Ou the basal portions of the froud, I fouud fuU-grown 



(CuRBTEXSEX, C. — Oii the iiatural classifioation of the species of Vryopteri-i, p. 75. 

 'Soi.EREDER, II. — Systeraatisclie Anatomie der Dikotyledonen, p. 937. 

 (2) Fee, A.L.A.— I.c.11. 231. 



