STRATIGRAPHY OF THE MIDDLE YANG-TZI PROVINCE. 281 
each species, we find, omitting all details, that Angiopteridiwm richthofent 
does not seem to have been found elsewhere. Its well-marked fertile fronds 
belong to a type represented by Angiopteridium minster, characteristic of 
the Rhetic in Europe. Cladophlebis petruschinensis is illustrated by a 
poor fragment regarded as identical with Heer’s plant from beds sup- 
posed to be Jurassic in eastern Siberia. Several eminent paleobotanists 
synonymically refer this species to Cladophlebis dentata (Brongn.) Nath., 
common and widely distributed in the Jurassic. But specimens which, 
to judge by the figures, are as near Schenk’s plant as are Heer’s types 
were figured by Schmalhausen from beds now generally admitted to be 
Permian on the lower Tunguska and in Petchora. Much doubt existed in 
Schenk’s mind as to the nature of his Rhabdocarpos densus, which he 
regarded as either an inflorescence or form of fructification. A thorough 
study of this fossil, to which the name Rhabdocarpos should not be applied, 
and which is probably Cycadean, may result in interesting and important 
paleobotanical information. As remarked previously, the species is not 
recorded from any other locality. Schenk considered his Nilsonia as too 
near Nilsonia compta for separation; but, whatever the degree of doubt 
as to the specific identity, it appears to be closely related to that plant. 
The presence of Nilsonia is significant in that it points to Jurassic or 
Upper Triassic age, most of its species being confined to the Rhetic, Lias, 
and Oolite. 
Both Pterophyllum nathorsti and Pterophyllum contiguum are reported 
from beds regarded as Oolite in age in Oregon, Pterophyllum contiguum 
being found also in the Rhetic of Hongay in Tonkin. The genera Ptero- 
phyllum and Podozamites both had a long existence, the former dating from 
the latest Carboniferous, while the latter extends from the Triassic to the 
Middle Cretaceous. Podozamites emmonsi, said by Newberry to be abun- 
dant in the Pumpelly collection, is typical in the Carolinian Triassic, while 
Podozamites lanceolatus is common in the Rhetic and Oolite. Consulta- 
tion of the literature shows nearly the same range for Czekanowskia rigida, 
to which Schenk referred one of Richthofen’s specimens, though, if Schmal- 
hausen’s identification is valid, the species dates back to the Permian. 
This seems somewhat improbable. Araucaria prodromus, the last of 
Schenk’s species, is not reported elsewhere, and from both his discussion 
and small illustration we must conclude that it is very ambiguous and of 
little importance. 
From the above very brief summary it appears that the direct evi- 
dence offered by the distribution of the individual species of this very 
insufficient flora points to a Mesozoic age, probably not older than Rhetic 
nor younger than Oolite. The testimony of Angiopteridiwm richthofent 
