246 
BULLETIN OF THE NATURAL HISTORY SOCIETY. 
comparatively deep waters in the center, and sands at its margin 
and in the river channel ; the deposits in the outer parts of the 
basin being black silicious mud, but in this later time, i. e., that 
of the Cordaite shales the silting up of the basin (or elevation of 
its bottom) choked the outlets of the river and led to the formation 
of a deltaic deposit, covering the whole basin ; here were entombed 
in the shallow pools of its surface the remains of numerous 
species of plants, remarkable for their high phytological stand- 
ing, and for the delicacy of their foliage. These plants (of the 
third column of the list) were twice as numerous iin species as 
those of the Dadoxylon sandstone; and it will be noted that 
while a large number of the group Equisetales are present, the 
species here classed as Pteridophyta and Pteridosperma largely 
preponderate. 
The geological history is thus a record of a long quiescent 
period, extending from the Medina to the eind of the Niagara 
and iin some parts of New Brunswick probably through the 
Upper Helderberg Time. During this time southern New 
Brunswick was the border of a large oceanfc island, shut off from 
the rest of America by sounds of the sea crossing New Brunswick 
and Maine, and having a land flora and fauna, so far peculiarly 
its own, but prophetic of that of the Coal Measures. An exception 
to the university of this telluric calm in Acadia in the Silurian time 
is seen in Charlotte county and further west in the State of Maine, 
where volcanic effusives appear at the top of the terrane which 
accumulated there in Silurian Time. 
