Scientia Sinica

No. i SZE: CORRELATION & AGE OF YENCHANG FLORA 151

It should be remarked that there are no typical elements of the Upper Jurassic and Lower Cretaceous Ruffordia-Onychiopsis flora of Eastern Asia in this Kazakstan coal series. This coal series cannot, therefore, be younger

than the Middle Jurassic.

The Yenchang flora of Northern Shensi may also be roughly equivalent to the Upper Triassic flora of Arizona, North America. The percentage of species common to the two regions is not high, but the close relationship of the two floras -is apparent. This Arizona Upper Triassic flora contains, likewise, the following genera: Eguisetites, Neocalamites, Cladophlebis, Danaeopsis (Daugherty wrongly determined as Ctenis arizonicus), Phlebopteris (=Daugherty’s Laccopteris), Sphenopteris, Podozamites, etc. It appears that the species Equisetites bradyi of Arizona"! is hardly distinguishable from our Equisetites sarrani and the species Cladophlebis microphylla is very similar to our Cladophlebis graciles. Sphenopteris arizonicus agrees well with our Sphenopteris sp. and Laccopteris smithti is closely related to our PAlebopteris lineartfolia. In addition, the specimen Yuccites poleonsis Daugherty") may belong to a species of Neocalamites and the specimen Ctenis neuro pteroides Daugherty'? may possibly be a Danaeopsis of the Danaeopsis fecunda type. This specimen should be determined under the name of Danaeopsis? sp. The specimens described by Daugherty!) as Podozamites arizonicus are apparently not a new species and in regard to the size and the shape of the leaves, they are almost indistinguishable from certain forms of Podozamites lanceolatus (L. & H.) Braun. It is surprising to find in the list of species from the Arizona flora a species of Coniopteris which is one of the most typical European and cosmopolitan Jurassic forms. Daugherty stated: “The sterile fronds or sterile parts of the fronds of this species closely resemble Sphenopteris nystroemu described by Halle from the Permian of China, but the fertile fronds more closely resemble Comiopteris hymenophylloides Brongniart from the Jurassic.” Judging solely from the illustrations'?, the present writer cannot express definite opinions, but it seems to him that the species of the Upper Triassic formation of Arizona is quite distinct from the Jurassic species Comiopteris hymenophylloides Brongn. and that these specimens might more appropriately be referred to the genus Sphenopteris. The Arizona flora contains also a typical Middle Keuper species of Virginia, that is, Lonchopteris virgimiensis Fontaine'!, In habit, the frond of this American Keuper species agrees with Cladophlebis whitbyensis, but the lateral veins form an anastomosing system like that in the Paleozoic genus Lonchopteris. Regarding the systematic position of this American Keuper species, Prof. Seward! pointed out: “Seeing that Lonchopteris is a designation of a purely provisional kind, it would be convenient to institute a new generic name for Triassic species having the Lonchopteris venation, which there are good reasons for regarding as Osmundaceous ferns.” A more or less similar form was described by Leuthardt"! as Pecopteris (Lonchopteris) reticulata from the Middle Keuper flora of Basel, Switzerland.