84 ANNALS NEW YORK ACADEMY OF SCIENCES 



gangamopterids known to occur in the northern portion of the northern 

 hemisphere. 



Conformably underlying this lower Gondwana flora are the Orleans 

 conglomerates of southern Brazil, which are supposed to be related to the 

 Dwyka conglomerates of South Africa, the Baccas Marsh conglomerates 

 and their equivalents in Australia and Tasmania and the Talchir con- 

 glomerates of India. These conglomerates contain some of the evidence 

 for the alleged Permian glaciation of the southern hemisphere. 



At 135 meters above the granite, i. <?., about 80 meters above the typi- 

 cal lower Gondwana flora, is found the intermingling of this flora with 

 some species of the older northern cosmopolitan flora. In this forma- 

 tion were, found Equisetes calamitinoids, Schizoneura, Sigillaria aus- 

 tralia, Sphenopters liastata (?), Glossopteris indica, G. ampla, G. occi~ 

 dentalis, Noeggerathiopsis hislopi and Cardiocarpon oliveiranum. The 

 flora is still primarily Gondwana. At a still higher level, 157 meters 

 above the granite floor or 100 meters below the Iraty shales containing 

 Mesosaurus, are found more of the northern flora, such as Lepidodendron 

 perdroanum, Lepidophloios larcinus and Sigillaria orardii. At this 

 level, the lyeopods are again preeminent as coal makers. 



The Gangamopteris flora is very imperfectly known, but what is known 

 indicates almost beyond a doubt that the Gangamopteris belong to the 

 southern hemisphere. It is not known from North America and is only 

 known from the late Permian of Eussia. The question is, then, Are the 

 known facts concerning the Gangamopteris flora indicative of a contin- 

 uous Gondwana Land somewhere in the southern hemisphere? Before 

 attempting to settle this difficult question, it is necessary to consider the 

 origin and the environmental complexes of this flora. 39 



The Gangamopteris flora belongs, as Professor Arber and Dr. White 

 have well shown, almost exclusively to families already known in the 

 cosmopolitan flora. They constitute genera and species more or less 

 bound to their northern relatives, though often differing much in form 

 and aspect. In general, they appear simpler in figure, with a tendency 

 to thickness and rugosity of leaves, and on the whole their general aspect 

 suggests environmental conditions unfavorable to luxuriant growth. This 

 flora suddenly appears in the early Permian well defined from its Car- 

 boniferous ancestors, which lived in the northern hemisphere and sur- 

 vived more or less the profound geological changes produced by the for- 



39 It is barely possible that the lower Gondwana flora of Brazil belongs to a later Per- 

 mian than now believed, as Professor Branner states in his Geologia Elemental- that the 

 intercalated marine deposits containing Sehisodus, Myalina and Conocardium also con- 

 tain other lamellibranchs also found in the Triassic. If this is found to he the case,, 

 then the appearance of this flora in Russia-Siberia may have been as early as in BraziL 



