SELLARDS.| Fossil Plants, Upper Paleozoic, Kansas. 439 
the frond is Protoblechnum Lesqx. The type, and only spe- 
cies of Protoblechnum known, comes from near the base of 
the Coal Measures, at Rushville, Ohio, and was first described 
as Althopteris holdem by Andrews.?%2 Lesquereux afterward 
made Andrews’s species the type of the genus Protoblechnum 
Lesqx. P. holdent (And.) Lesqx. has, like the species of Glen- 
opteris, sessile, auricled pinnules, reduced at the base of the 
petiolate frond. The estimated length of this species, 50 to 
60 cm., is only slightly larger than that of the largest species 
of Glenopteris. The apical part of the frond of Protoblechnum 
differs, however, entirely from that of Glenopteris. In the 
several species of Glenopteris the pinnules are reduced gradu- 
alley toward the apex of the frond, at last uniting with a 
terminal pinnule. The frond of Protoblechnum is represented 
as ending abruptly, the pinnules not at all reduced. It might 
be suspected that the apex of the specimen was gone, espe- 
cially as the rachis continues moderately strong to the very 
last, were it not that both authors agree in describing the 
frond as complete. Lesquereux says (Coal Flora, p. 188): 
“The upper ones (pinnules) are close, less distinctly scythe- 
shaped, but quite as long, the terminal leaflets being still 6 cm. 
long.” The venation of Protoblechnum Lesqx. is apparently 
distinct, the veins twice forked; the venation of Glenopteris 
is indistinct, and often obliterated, the veins simple or forked 
once. The thick coating of scales on the rachis of Proto- 
blechnum is a character not seen on any species of Glenopteris. 
Glenopteris cannot be closely compared with any other genus 
of Carboniferous ferns. It has, however, in the sessile decur- 
rent pinnules, a general relation to all the genera of the ale- 
thopteriod group, to which it accordingly finds its most natural 
reference. The relation after Protoblechnum Lesqx. is per- 
haps closest to Alethopteris St. But the genus differs from all 
the other alethopterids, again excepting Protoblechnum, in the 
simple fronds and large pinnules. Glenopteris has a suggest- 
ive resemblance to some of the callipterids, especially species 
of Callipteris having large pinnuled fronds. The apices of 
the fronds of Glenopteris have a peculiar resemblance to 
Odontopteris. So striking is this resemblance in Glenopteris 
simplex that the apex, if found detached, unassociated with 
the rest of the frond, would probably be taken for a large 
298. Geol. Survey of Ohio Pal., vol. 2, p. 420, pl. LI, figs. 1-2a. 
