— 373 — 
Yet, judging from the meagre data in hand it would appear that, 
following a continental movement and a concomitant period of severe 
climatic change,fthe region was possessed by a typical and pure Gan- 
gamopteris flora, which, as the climate, ameliorated o1 the difficulties 
of migration were overcome, was gradually invaded by representati- 
ves of the Northern Lepidophytes, mingled, perhaps, with forms 
indigenous to the transitional zone. 
As we ascend in the coal bearing series the number of nor- 
thern species or their probable derivatives appears to increase until, 
in the Barro Branco coal, we find that the greater part of the car- 
bonaceous matter seems to have been contributed by Lepidodendron 
and Sigillaria. 
The presence of Psaronius near or above the Iraty black shale 
in the series creates and substantially fosters the expectation that 
fronds of the [Pecopteris, or, more probably, of the Cladophlebis 
groups will later be found in this part of the series, showing that, 
with the restoration of uniform climatic conditions, the hardier forer- 
unners in the Lepidophytic group were followed by representatives of 
the northern or cosmopolitan groups of ferns. 
Foreign distribution of the species 
The principal criteria for the cerrelation and age determination 
of the Brazilian coals are those afforded by the records of the dis- 
tribution of the fossil plant species. This evidence, as we shall see, 
is in general remarkably clear and direct. 
Among our species which occur in other continents, or which 
have very closely related foreign species, are the following: 
1. Reinschia australis (*), from the kerosene shale, New South 
Wales. 
2. Rosellinites Gangamopteridis, apparently closely related toa 
form in the Raniganj of India. 
3. Hysterites brasiliensis, closely related to a form from the 
Rothliegend of Thuringia. 
4. Phyllotheca Griesbachi, from the Barakar group in India, and 
related to Phyllotheca australis from the Newcastle series, New South 
(*) See note on pag. 407. 
