III. 
THE FERN FORESTS OF THE CARBON- 
IFEROUS PERIOD. 
D RAW two lines on your map, the upper one 
running from the mouth of the St. Law- 
rence westward nearly to St. Paul on the Missis- 
sippi, and the lower one from the .neighborhood 
of St. John’s in Newfoundland, running south- 
westerly about to the point where the Wisconsin 
joins the Mississippi, but jutting down to form an 
extensive peninsula comprising part of the States 
of Indiana and Illinois, and you include between 
them all of the United States which existed at 
the close of the Devonian period. The upper 
line rests against the granite hills dividing the 
Silurian and Devonian deposits of the British 
Possessions to the north from those of the United 
States to the south, Canada itself consisting, in 
great part, of the granite ridge. 
How far the early deposits extended to die 
north of the Laurentian Hills, as well as the out- 
line of that portion of the continent in those 
times, remains still very problematical ; but the 
