Scientia Sinica

No. 1 SZE: CORRELATION & AGE OF YENCHANG FLORA - a

species 1s somewhat different and that there are numerous globular prominences or dots between the nerves of this species. As explained by Fontaine, these dots do not seem to be anything but a fine granulation of the epidermis; sometimes, owing to distortion from pressure, these dot-like elevations are drawn out into little bars which extend from nerve to nerve and look like transverse nerves. It is interesting that in regard to the size of the leaf, there are no known species of Sphenozamites which could be compared with Sp. rogersianus from the Virginia-Keuper and with Sph. changi from the Yenchang Formation. The form Eguisetites? sp. (cf. E. rogersi Schimper), resembles also E. rogersi''**! from Virginia in regard to the shape and the size of the teeth of the leaf-sheath, though the evidence is not conclusive; it should probably be referred to the same genus. According to P’an!*!, the specimens of Danaeopsis in the Yenchang flora bear a close resemblance to Pseudodanaeopsis obliqua (Emmons) Fontaine!" and Pseudodanaeopsts plana (Emmons) Fontaine!*, but in our species, the secondary veins are not so frequently anastomosed and furthermore the pinnae are broader as compared with those of Fontaine’s species. Dr. Lundblad" is of the opinion that, in the light of the evidence brought forward in the last decades, even the filicinean affinities of the type of Fontaine’s genus seem very doubtful, on account of the features of the rather thick and coriaceous leaf-substances. Lundblad believes that the North American plant might, in reality, be a gymnosperm, and with this view, one can well agree"*!. Finally, the species Sphenobaiera crassinervis sp. noy. bears also a certain resemblance to the American species Sphenobaiera multifida (Fontaine) Florin™, In any case, the points of resemblance between the Basel, the Lunz and the Virginia floras of Europe and America on the one side and the Yenchang flora of Northern and Northwestern China on the other as expressed in the number of related forms are quite significant.

In addition to the species closely similar to the characteristic species of Basel, Lunz and Virginia, there are some other forms which tend to give the Yenchang flora an aspect typical of the Keuper. All the new species of Equisetites, such as E. sthenodon, E. deltodon, etc., are closely comparable to Equisetites platyodon Brongniart* ", an index fossil of the Schilfsandstein (Middle Keuper) of Southern Germany and Northern Switzerland in regard to the size of the stem and the shape of the teeth of the leaf-sheath. In the large size of the stem, the species Equisetites arenaceous Jager, one of the most abundant plants of the Keuper formations (Lettenkohle and Schilfsandstein) in Europe can also be compared with the present new species of the Yenchang Formation. The occurrence of the new species of Neocalamites, Neocalamites rugosus Sze sp. nov. in the collection is of special importance, since it bears an aspect of an older age of the Yenchang Formation. This species agrees, in the marked zig-zag lines of the outer surface of the cortex, fairly well with the species described by Jongmans as Calamites rugosus of the Westphalian age!” . The presence of many specimens of this peculiar