834 OLDER MESOZOIC FLORAS OF UNITED STATES. 
the form of its sterile pinnules it is a good deal like Schenk’s Sphenopteris Ressertiana, 
described in his Foss. Fl.d. Grenzschichten. This is quite rare.! 
6. Acrostichites princeps (Presl) Schenk? This fern is one of the most common and 
best preserved. In both the shape of the pinnules and the granulation that covers 
the fructified pinnules it agrees pretty closely with Schenk’s Acrostichites princeps, from 
the Rhetic of Europe. The pinnules, like those of the latter, are small, with margins 
more or less undulating, and when fructified, as they mostly are, they are covered 
with sori. The amount of material does not suffice, I think, to make the identifica- 
tion positive. 
7. Sagenopteris or Cheiropteris. This is a fragrant of what seems to have been a 
rather large leaf with very thin texture. It shows a border which may be a portion 
of the extremity of the leaf or of a lateral margin. The nerves are approximately 
parallel, thin, and not distinct. They anastomose at considerable intervals, so as to 
give long meshes. The nervation seems nearer that of Sagenopteris than any other 
fern. If it is a Sagenopteris the leaflets are larger than those of any described species 
of that genus. Only one specimen was seen.? 
According to this list; the plants now in question would seem to find their nearest 
affinities in the Rhetic flora of Franconia, as described by Dr. Schenk. 
Professor Diller, in a paper published the following year,’ gives (p. 
374) a condensed statement of Professor Fontaine’s report, but it has 
never before been published entire. Another collection was made in 
1893, but the material was even poorer than the rest, and it has been 
impossible to determine it. The record will, therefore, have to close 
with Professor Fontaine’s report above, but it is greatly to be hoped 
that some better locality may yet be found and further light shed on 
the flora of these beds. 
PART ITI. 
THE JURASSIC FLORA. 
PLANT-BEARING DEPOSITS SUPPOSED TO BE JURASSIC. 
It is not, of course, proposed here to go over the ground so long 
under discussion relative to the Triassic deposits considered in the last 
chapter, although the Richmond coal field was first regarded by Rogers 
as Oolite, and Mr. Marcou first referred those of the Southwest to the 
Jurassic. This question we will consider as settled, and whether, with 
Professor Fontaine, we place the highest of them in the Rhetic or 
regard them all as more probably representing the Keuper, we may 
at least include them all in the American Trias. 
The deposits now to be considered are recognized by all as lying 
above these last, and the ones that have been under discussion are so 
much higher that the question has always been whether to regard them 
as Jurassic or as Cretaceous. Neither do I now propose to open up the 
questions relative to the alleged Jurassic age of the Potomac formation 
1This can bear the name Acrostichites brevipennis Ward, n. sp. 
2¥From the large leaflets this may be called Sagenopteris? magnifoliola Ward, n.sp.. 
3 Geology of the Taylorville region of California: Bull. Geol. Soc. America, Vol. III, 1892, pp. 369-394, 
