1 66 THE BOTANICAL MAGAZINE. [Vol. xxix. No. ™. 



opening becomes narrower and narrower, and at length the 

 depression sinks down into the tissue forming a pouch-like 

 cavity with a linear orifice beset with bristles. In my speci- 

 mens, the orifice, quite contrary to Fee's statement, is present 

 at the very beginning of the sorus-formation, and is not at all 

 a slit that appears as a secondary result of the bursting of 

 the epidermis. The sorus-formation in the earlier stages is 

 almost the same as that of a normal Polypodium, but differs 

 in having receptacles in the depressions. Such depression is, 

 by no means, absolutely exceptional in Polypodium, as we find 

 it in P. repandulum, P. papillosum and others. P. obliquatum 

 is simply an example of an extreme case having depressed sori. 

 Several stages connecting this extreme form with the normal 

 one are represented by several species of the genus, just as they 

 are represented in one series in the process of sorus-formation 

 in one and the same frond of P. obliquatum. That Crypto- 

 sorus is directly derived from a normal Polypodium is thus 

 clearly indicated. Consequently, there can be no doubt but 

 that Cryptosorus is phylogenetically congeneric with Polypo- 

 dium. Tne former is generally regarded as a subgenus of the 

 latter by leading Pteridologists, such as Baker, Christ and 

 others. 



Now turning again to Prosaptia, I shall consider the devel- 

 opment of the sori of P. Emersoni. This fern also exhibits an 

 indefinite growth representing several stages of sori in one and 

 the same frond. Sori are located at the apex of the margin of 

 the lobes with long U-form cavities with dors ally compressed 

 orifices at the apex directed parallel to the surface of the frond 

 — in every respect exactly like those of Davallia. But, in the 

 very beginning, the sorus-formation commences with a depres- 

 sion a little inside the extreme edge of the margin on the under 

 surface, as may be seen nearly, if not exactly, in the case of 

 Polypodium obliquatum. As the sorus develops, the depression 

 grows deeper and deeper with the edge more or less elevated ; 

 then sporangia come into sight. When fully grown, it becomes 

 a sorus different in appearance from that of Cryptosorus, but 

 very similar to that of Davallia. Yet, gradually transitional 



