8 ROYAL SOCIETY OF CANADA 
The portion of the Little River group which contains the Filicoid 
genera above described, that are so like those of the Coal Measures, is 
that by which its flora is best known, from containing mostly 
species described by Sir William Dawson; but sufficient emphasis has 
not been given to the fact that only a certain part of the plant remains 
of this group has been exploited; both the underlying and over- 
lying parts of the group have a considerable flora and yield species 
differing from those of the rich collecting ground where Prof. Hartt and 
others made their chief gatherings. 
But although there are these differences in the genera, and species 
of plants of this group at different horizons, its flora possesses a unity 
of aspect in strong contrast to theDevonian flora which came after. So 
wide is the difference in the composition of the two floras that we must 
look upon them as having flourished under very different conditions of 
soil and climate. The conditions under which the Coal Flora grew, 
have received careful study and from these we may infer similar condi- 
tions in southern New Brunswick when the plants of the Little River 
Group were living. 
But the influences surrounding the Devonian Flora when it flou- 
rished in the same region must indeed have been different. The condi- 
tions of climate which would seem to have best suited the Devonian 
types was that of a dry and cool atmosphere, broken annually by a short 
period of rains, when the short and scanty vegetation made a rapid 
growth. Such conditions at least would best accord with the preva- 
lence of xyrophytic forms like the Psilophyta and the small leaved 
Lepidodendra, and the rarity of the Equisetinæ. Broad leaved plants 
like the Cordaites are rare in the Devonian vegetation and the Filicoid 
plants are mostly of the genus Archæopteris. The plants that did prevail 
are mostly recorded as having had rhizomes or fleshy root stalks, and 
in these could have stored up the nourishment which enabled them to 
throw out a vigorous growth at that time of the year when the season 
of expansion arrived. 
To account for the very diverse floras that appeared from time to 
time in North-eastern North America, one may suggest some such 
succession of events in Palzeozoic Time as the following :— 
(1). The oldest flora that we know is so complex that a long period 
of Geological time would have been required for its differentiation, and 
development. As this flora with its complexities appeared near the base 
of the Silurian terrane, its ancestors must have far antedated that time. 
(2). Moreover, it is not plants alone, but various types of animals of 
the land that appeared, which also show an early development, such as 
‘Since this was written a still older flora has been discovered in a lower 
group of this terrane. 
