330 POLTrODIACE.E. 



sori ancl in the iijiper portions half-grown ones, wliile in the upiicrmost pir- 

 tions of the same frond there apj)eared the very beginning of sorus-formation. 

 In thc begiuning, the soras (Fig. 137-g) looks like a mcre clepression of thc 

 surface ; this depression grows larger and deeper and becomcs cup-shaped ; 

 sporangia theu first appear at the center of the cuii. The depression grows 

 still deeiier and largcr, Lut the opening "bccomes nai-rower and narrower, and 

 at lcngth tlie depression sinks down into the tissue forming a pouch-like cavity 

 with a lincar orifice beset with bristles. In my specimens the orifice, quite 

 coutrary to Fee's statement, is jirescnt at the veiy bcginning of the sorus-for- 

 mation, but is not at all a slit which appears as a secondary result of the 

 bursting of the epidermis. The sorus-formation in tlie earlier stages is almost 

 thc same as that of a uormal Foli/podium, Imt difters in having rcceptacles 

 in the dexiression. Such a deiiression is, by no means, absolutely exceptional 

 in Polypodium, as we see in P. rcpaiuhdum, P. papillosum and others. P. 

 ohliquatum is simply an cxample of au exti-eme case having depressed sori. 

 Several stages connecting this extreme form and the normal one arc repre- 

 sented by several specics of the genus just as they are represented in one 

 series in the process of sorus-formation iu one and the same frond. That 

 Cryptosorus is directly derived from a UDrmal Polypodium is thus clearly in- 

 dicated. Consequently, there cau lie no doubt but that Oryptosorus is phylo- 

 genetically congeneric with Polypodium. The formcr is generally regarded as 

 a subgenus of the lattcr by leading pteridologists, sucli as Baker, Cheist and 

 otliers. 



Now turning agaiu to Prosap)tia, I sliall consider the development of tlie 

 sori of P. Emersoni and P. celehica. Thcse ferns also exhibit an indefinite 

 growth, representing several stagos of sori iu one and the same frond. Full 

 grown sori are located at the apex of the margin of the lobes with long U- 

 form cavities with dorsally compressed orifices at the apex dirccted parallel to 

 the surfacc of tlie frond, and in every respect exactly like those of DavalUa. 

 But, in the very bcginning, the sorus-formation (Fig. 137, h-i) commences 

 with a depression at a little below the extreme edge of the margin on tlie 

 under surface, as may be seen nearly, if not exactly, in tlie case of Pohjpodium 

 ohliquatum. As the sorus develops, thc depression grows deepcr and deepcr 



