PHILIPPINE FERNS, IV. 115 



PROSAPTIA Presl. 



Prosaptia linearis Copel. sp. nov. 



Species distinctissima ; rhizomate subrepente, ad apicem paleis angustis 

 cancellatis atro-fuscis ciliatis vestito; stipitibus confertis, exarticulatis, 

 brevibus ; fronde usque ad 40 cm longa, circiter 16 mm lata, pinnata, rhachi 

 tenue, nigra, ubique glabra ; pinnis late adnatis non co-nfluentibus, acutis, 

 integris, coriaceis, inferioribus sensim in dentes diminutis; soro in pinna 

 quaque uno, costa orto, profunde immerse-, apud vel ad marginem acrosco- 

 picnm apcrto, annulo inaequale ciliato circumdato. 



Luzon, Province of Benguet, Mount Pulog, For. Bur. 16303 Curran, Mcrritt, 

 d- Zsclwkke, on mossy trees, altitude 2,700 m, Cvpcland. 



A bizarre fern, resembling Loxoscaphc in the appearance of the fruit. The 

 solitary sori and the very narrow fronds strongly suggest Acrosorus, but the 

 origin of the protection of the sorus is very essentially different. Small fronds 

 are so similar to those of Poly podium decorum that I at first regarded it as 

 derived from that species, and therefore to be treated as generically new, rather 

 than included in Prosaptia. However the paleae are like those of Prosaptia, 

 while those of Polypodium decorum have thinner walls and are not ciliate. 



The tip of the pinna is produced as a sharp point beyond the sorus, and bent 

 toward the tip of the frond. As the fronds are pendent these tips serve to 

 drain off water and protect the sori from wetting. The ecological significance 

 of the movement of the sori to the margin, found independently in many groups 

 of ferns, I have before interpreted ; as also the value of the rim, and the circle 

 of hairs around the sori. 



