250 UnpERWooD: AMERICAN FERNS 
Sturm, who showed that the extension of range of G. pubescens 
at least was southward from its type locality rather than north- 
ward. Recently Dr. Christ has delimited a number of Costa 
Rican species, unfortunately with very poorly prepared material 
and probably without due reference to the species of South 
America. A number of his species have been re-collected in ex- 
cellent specimens by Mr. Maxon, but much more field work in 
that prolific region will be necessary before we reach the end of 
our knowledge of the range of species. We have separated 
thirteen species in this section with three others still in the position 
of spectes inquirendae. 
3. The section Acropterygium of Diels is characterized by bear- 
ing no segments on any of the internodes, the branches all terminat- 
ing in a single pair of pinnae. To this section belongs D. pectinata, 
of wide distribution, one of the most graceful of the genus.* 
4. The last section, Heteropterygium of Diels, is most peculiar 
of all in its branching. As in the Jast section there are no decur- 
rent segments, but after the second forking and each succeeding 
one, a branch is deflected downwards on either side of the fork so 
as to make an angle of about the same degree of aperture as the 
fork itself. These deflected pinnae may be nearly as large as the 
regular pinnae of the plant or, in other species, may be reduced 
toa simple pinnule only slightly larger than the ordinary seg- 
ments of the pinnae of the same plant. The type of this section 
as well as of the genus Dicranopteris is the plant described by 
Thunberg from Japan as Polypodium dichotomum. It is uncertain 
whether the Malayan plant which has a still earlier name 1s 
identical with this species or not.+ In any case the American 
ers 
*Commencing with Raddi, followed by Hooker (Sp. Fil. 1: 11,12. 1844), 
Mertensia glaucescens H. & B. has been reduced to synonymy with this species, with- 
out taking the trouble to examine Willdenow’s type. The species proves to be 4 
member of a distinct section (Holopterygium) from the present species and is to be 
compared with the glaucous species of that section more recently described from South 
America. The type locality of J/. Slaucescens is Santa Cruz, Venezuela. 
t The Malayan plant has been called Gleichenia linearis and has the following 
synonymy : 
Dicranopteris linearis (Burm. ) 
Polvpodium lineare Burm, F1. Ind. 235. pl. 67. f. 2. 1768, (type from Java); 
not Polypodium lineare Thunb. which belongs to a distinct family, but as a homony™ 
will require a new name when placed in its proper genus. 
Gleichenia linearis Clarke, Trans. Linn. Soc. II. 1: 428. 1880. 
ee 
