622 DAVID WHITE 
the refrigerated area, or to a more rapid and well-marked modera- 
tion of the climate. : 
Evidence oj equable climate during Passa Dois deposition—The 
fossil-plant material collected from higher horizons of the Brazilian coal 
measures unfortunately consists only of fossil stems; but these 
furnish almost unmistakable evidence of a mild and equable climate. 
From beds near the top of the Tubarao series, in Rio Grande do 
Sul, not far above the horizon last mentioned a gymnospermous type, 
Dadoxylon (?) meridionale, was collected. Another horizon some- 
what higher, or about 75 meters above the base of the Passa Dois 
series, in the same state, furnished Dadoxylon (?) nummularium and 
atree Lycopod of large size, Sigillaria (?) muralis. Still another 
fossil Lepidophyte, Lycopodiopsis Derbyi, was found at 155 meters 
above the Iraty black shale in the state of Sao Paulo. The Iraty 
black shale, which has been definitely traced by Dr. White throughout 
the region, is probably the source of the Dadoxylon (?) Pedrot Zeill., 
and of Brongniart’s Psaronius brasiliensis. It is also the horizon of 
Cope’s Stereosternum tumidum as well as of the Mesosaurus brasil- 
ensis McGregor, collected by Dr. White. 
Even more importantly significant than the presence of the arbores- 
cent Lycopods, from the climatic standpoint, is the complete or 
almost total absence from the various fossil woods of all trace of 
annual rings. On the other hand annual rings are conspicuously 
developed in the trees described by Arber* and Shirley? and found 
associated with the pure GANGAMOPTERIS flora in beds overlying the 
glacial conglomerates in New South Wales and Queensland. The 
sensible abatement of climatic rigor indicated by the appearance of 
the Lycopods in the upper part of the Tubarao series in Brazil is 
thus confirmed by the uninterrupted growth in the fossil trees from 
the still higher beds, during whose deposition there appear to have 
been no marked seasonal changes of climate. The presence of the 
large Lycopods and of the Psaronius trunk in the Passa Dois series 
warrants the expectation that further search will reveal a pteridophytic 
and gymnospermous flora closely related to the contemporaneous 
1 Catalogue of the Fossil Plants of the Glossopteris Flora in the Department of 
Geology, British Museum, 1905, p. 191. 
2 Geol. Surv., Queensland, Bull. No. 7, 1898, p. 14. 
