159 
IKiiili Christ. Polijpodiuiu bbicrve Hooker, Syn. Fil. I, p. 175, may al.so belong 
here. They liave a strong apparent, Imt merely a])[)arent, allinity to l‘ios(ijt(ia. 
especially to I’, contiijua. monosora, which likewise has a single apical immersed 
soriis in each pinna. But this position of the sorus has been attained in entirely 
dill'erent ways. The sorus of P. contigua was originally dorsal and deeply im- 
mersed; its cavity now opens toward the margin instead of dorsally. The form 
with single apical sori, though sometimes a feature of immature plants, is 
certainly derived from that with many marginal sori. The ancestors of Acro- 
sorus were Polypodia with superficial dorsal sori, one on each pinna, more or 
less protected by the dorsal concavity of the pinna, or the folding upward and 
backward of its basiscopic half, as now known in P. irichomanoides, P. cucullaium, 
I’, strcptophijllum, and P. gracilUminn. Acrosorus is unquestionably an offshoot 
from this group of Polypodium.. It is related to Prosaptia only through the, 
remote common ancestry of this group and that of P. obiiquatuvi. Combining 
Prosaptia and Acrosorus wordd violate the most fundamental principle of sys- 
tematic botany, by failing to make the classification exi)ress, as best we can, the 
real affinities of the plants. The remaining alternatives are the enlargement 
of the already cumbrous Polypodmm to include these plants, and the establish- 
ment of a new genus. Neither Prosaptia nor Acrosorus has any near affinity to 
Davallia. 
y Acrosorus exaltata Copel. (Table 15.) 
Da/vallia exaltxrta_CoAic]., in Perk, rragmenta FI. Phil., p. 180, 1005; 
Polypodiace* of the Phil., p. 52, 1905. 
\/ Acrosorus frederici et pauli (Christ). 
Davallia (jxdcrici cl pan/j) i2.hrist in Fil. Sarasin. II, ]>. 124, Tab. I; 
Farnflora v. Celebes, p. 94, Tab. 14, 1904, Farnkr. d. Erde, p. 306. 
Poly podium frederici ei pauli Christ in Farnflora v. Celebes, II, p. 37. 
POLYPODIUM Linn. 
Polypodium dolichosorum Copeland n. s[>. 
lihizoiuate late repente, 1 mm. crasso, paleis fiilvis amplis ovatis 13-4 
mm. longis vestito; stipite cluro, fnsco-nigro, pills rubidis vix 1 mm. 
longis vestito vel deorsum glabro, ca. 4 cm. alto, non articnlato; fronde 
ca. 15 cm. alta, 1 cm. lata, ntrinque atteimata, apice obtiisa, integer- 
rima, glabra, coriacea, opaca; venis plerumque 2-furcatis; soris obliqnis, 
oblongis, in seriani nnam inter costam marginemque instructis, costam 
propioribns, panlo immersis. (Tal). 16.) 
Mindaj^ao, Davao, 1,800 m. s. m., Copeland 1524. 
A fern related to P. australe Mett. and P. caespitosuin (Blume) Mett., distin- 
guished by the long rhizome, long, stout stipes and coriaceous fronds. Found 
on the ground, but pi’obably as much at home on trees. Many of the smaller 
plants of the very humid forest grow indiscriminately on trees and on the ground. 
Not a few Eupolypodia in sucli places have nonarticulate stipes. 
Polypodium decrescens Christ, Ann. Jard. Buitenz. II. 4: 35. 1904. (Tab. 17.) 
Luzon, Lepanto, Bagnen, Copeland 1916. De truncis pendente, 1900 in. s. m. 
Celebes. 
This species is very similar to P. subsessile Baker (P. pteropus Hooker, Sp. 
Fil. 4: 192, PL 27.5), of South America; but its pimiiE are much closer together 
and less dilated at the base. 
42124 2 
