Nov, 1913.] 
The Classification of Plants, X. 
199 
steles of known Pteridophytes is too great to be bridged unless 
fossil forms can be found intermediate between the two. Since 
these forms should be discovered in the Ordovician, Silurian, or 
Cambrian rocks or perhaps in deposits of even earlier age, there is 
no immediate prospect of their coming to light even if any were 
preserved. The Silurian and Ordovician should be thoroughly 
searched for Pre-Devonian Pteridophytes for Ordovician fossils 
might give a clue as to the possible path along which the vascular 
plants evolved. In the meantime it is most reasonable to classify 
our living species on the basis of their entire morphology both 
internal and external. 
Correction. 
Through inadvertance the genus, Microcycas appeared as Micro- 
zamia in the IX paper of this series (Ohio Naturalist 13: 106). 
Read Microcycas instead of Microzamia. 
In the following synopsis the segregation has been carried as 
far as the genus except in the complex Polypodiaceae which well 
deserve an independent treatment. 
Synopsis of the Ptenophyta. 
I. Sporophyte homosporous, having only one kind of nonsexual spores; 
leaves usually large and mostly compound; gametophytes comparatively 
large, hermaphrodite or unisexual. Filices. Ferns. 
1. Plants eusporangiate, sporangia developed from internal cells. 
Eusporangiat.®. 
(1) . Sporangia on a special sporangiophore distinct from the 
leaf-blade; gametophvte subterranean, without chlorophyll. 
OPHIOGLOSSALES. OPHIOGLOSSACE^E. 
a. With reticulate venation; sporangia in a single row on 
both margins of the sporangiophore. Ophiogossum. 
b. With dichotomous venation, sporangia clustered on the 
sporangiophore or the sporangiophore more or less 
branched. 
(a) . Sporangia opening transversely; on the margin of 
a more or less branched sporangiophore. Botrychium 
(b) . Sporangia opening longitudinally; in little clusters. 
Helminthostachys. 
(2) . Sporangia on the underside of foliage leaves; leaves with 
two stipules; gametophytes with chlorophyll. 
MARATTIALES. 
a. Sporangia in sori but free from each other. 
AXGIOPTERI DACE.E. 
(a) . Sori very long, with 80-160 sporangia; leaves simply 
pinnate. Archangiopteris. 
(b) . Sori short, elliptical, mostly with 10 sporangia, 
sometimes less or sometimes as high as 20; leaves 
two or more times pinnate. Angiopteris. 
b. Sporangia united forming synangia. 
(a). Each loculus or sporangium of the synangium 
longitudinally' dehiscent. marattiace,e. 
((a)). Synangia elongated, oval, venation not 
reticulate; leaves large pinnately com¬ 
pound. Marattia. 
