NO. 1873. CHARACTERS OF GIGANTOPTERIS— WHITE. 513 



of Callipteris goepperti Morris, which may be its nearest known 

 relative. 



On the evidence of association, bract texture, and nervation, certain 

 obovate seeds borne in the ventral faces of rather large, cuneate- 

 obovate, distantly distichous bracts, and representing a new generic 

 type of fructification, are regarded as the probable fruits of Gigantop- 

 teris. Likewise, certain strobili, composed of two opposite rows of 

 distally concavo-convex reniform disks, bearing on their under sur- 

 faces numerous pendant oblong sacs are on account of the agreement 

 in the texture and filicoid nervation of the disks with the lamina and 

 nervation of Gigantopteris, provisionally referred, with a liigh degree 

 of probabiHty, as the poUeniferous strobili of that genus. 



The genus Gigantopteris is therefore regarded as a cycadofihc 

 (Pteridospermic) type. 



In Cliina (provinces of Hun-Nan and Yun-Nan) Gigantopteris 

 is associated with certain European Permian forms and a number 

 of American tj^pes, all shoM'ing the Permian age of the Gigantopteris 

 bearing beds. 



The very incomplete collections of fossil plants from the Wichita 

 formation in Texas, from its supposedly approximate equivalents in 

 Oklahoma, from the Chase and Sumner groups in Kansas, and from 

 the great series of undifferentiated "Red Beds" in the Rocky Moun- 

 tain region of southern Colorado, show a mixed flora embracing (1) 

 mainly representatives of the Permian flora of western Europe, and 

 including many types not previously known in North America; (2) 

 a smaller portion peculiar to the Gigantopteris association in south 

 central, and southwestern China; and (3) several types apparently 

 identical with or very close to forms hitherto known only in the 

 Permian of the Uralian region. 



The distribution of the floral elements indicates that the western 

 European or cosmopolitan elements of the flora migrated between 

 North America and Europe, presumably by the same general north- 

 eastern route as that followed by their Pennsylvanian predecessors, 

 while the distinctly Chinese types must have come to Texas and Okla- 

 homa by the north Pacific (Alaskan) route, by which the related 

 Uralian forms may also have migrated. Since the land migration of the 

 Chinese types could hardly have been accomplished without the aid 

 of essential continuity of environmental conditions, and since it is 

 probable that the Gigantopteris elements lived under climatic condi- 

 tions mainly similar in both Texas and China, the conclusion appears 

 justified that the climatic province under which they thrived in Asia 

 extended to western North America and that it included the region 

 of north Pacific migration. The mingling of western European 

 species with Gigantopteris in the southwestern "Red Beds" is con- 

 94428°— Proc.N.M.vol.41— 11 33 



