4 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. 62. 
and W. P. Woodring) it comprises 349 species, and suggests a middle 
Miocene age (Helvetian). Monographic studies of this fauna which 
are projected may of course modify this tentative opinion somewhat 
A brief sketch of the geology of the isthmus was published by 
Bose * in 1906 and in this paper the presence of fossil plants at several 
localities is mentioned although apparently no collections were made. 
Phylum PTERIDOPHYTA. 
Class LEPTOSPORANGIATAE. 
Order POLYPODIALES. 
Family POLYPODIACEAE. 
Genus GYMNOGRAMME (of authors). 
GYMNOGRAMME WADII, new species. 
Plate 1, fig. 2. 
The absence of fruiting material makes it impossible to determine 
the exact position of this characteristic fossil fern and I have therefore 
referred it to what must be regarded as a composite genus, Gymno- 
gramme. ‘This type of sterile pinnule is common to a variety of trop- 
ical ferns, as}forsexample, Lomariopsis, Blechnum, etc. The species, 
which is new, is named for the collector, and may be characterized 
as follows: Frond pinnate (?). Pinnules large, oblong-lanceolate, 
subcoriaceous, acuminate at both ends, about 14 cm. in length and 4 
cm. in maximum width. Margins somewhat irregular, entire, 
inclined to be revolute. Midvein wide, not prominent, channeled. 
Laterals prevailingly simple, closely spaced, parallel, diverging from 
the midvein at wide angles, approximately 90°, and nearly straight 
in passing outward to the margins, in which regions they curve 
slightly upward. 
This is a well marked element in the Tehuantepec Miocene flora. 
Among previously described fossil forms the only one approaching 
it is Gymnogramme woodringi Berry’ of the Miocene of the island of 
Haiti. Many recent American forms match it more or less closely. 
Occurrence.—Isthmian railroad 3 km. north of Palomares on 
Saravia estate, State of Oaxaca; 14 km. west of telegraph station San 
Jose del Carmen, State of Vera Cruz. 
Holotype.—Cat. No. 36811, U.S. N. M. 
6 Bose, E., Excursion a l’isthme de Tehuantepec, 10th Int. Geol. Congress, Mexico, 1906. 
1 Berry, E. W., Proc. U.S. Nat. Mus., vol. 62, art. 14. 
