SILURIAN FLORA. 
245 
shales, sandstones and conglomerates in which no plant remains 
have been found. At some points almost the whole group 
appears to be represented by volcanic efifusives. 
Upon this group rests the strata of No. 2 of the Mascareen 
series, represented in the eastern exposures mostly by the 
Dadoxylon sandstone. The latter, however, is the littoral or fluvial 
phase, for when followed to the west and south these sandstones 
are replaced by hardened black silicious shales, which give charac- 
teristic black sands at certain points along the coast of the Bay 
of Fundy; a beach of these sands is seen at Black Beach, in 
Musquash Harbor, and another at the village shore, in Beaver 
Harbor. 
The Dadoxylon phase is largely composed of river-sajnds, in 
which were buried rafts and single trunks of trees, swept down 
from the uplands of a Silurian interior country; hence these 
trees, including Dadoxylon Ouangondianum of Dawson, and 
other trees undescribed, are the only sure representatives that we 
possess of an upland flora of Silurian age. 
Associated in the sand beds with these trees are other, more 
perishable plants, mostly of the Equisetaceae, that flourished and 
grew iin the sands themselves. 
Finally there was a third group of plants also contained in 
the sandstone deposit, but in finer shaly beds, which represent 
to us the more delicate of the Eauisetales, and still another type, 
plants of higher grade that lived on the higher parts adjoining 
the pools among the river sands. Many of these plants fall in 
the group Pteridophyta and Pteridosperma of the accompanying 
list. This, then, was the nature of the fauna of the second 
column presented in the list. 
A much richer fauna, that described by the late Sir William 
Dawson, the late Professor C. F. Hartt, and others, is found in 
the overlying group (Lower Cordaite shales, at St. John, No. 3 
of the Mascareen series, Silurian, in Charlotte county). This 
fauna is contained in alternations of clay and sand and marks 
the advent of true deltaic conditions ; previously in the time 
marked by the Dadoxylon sandstones the Silurian basin had 
