442 BOTANICAL GAZETTE | DECEMBER 
the abundant heath bushes.*s In places on the floating bog, 
especially near its margin, one sees occasionally dense mats of 
Hypnum several feet across, indicating no doubt the beginning 
of flat bog formation. In general this association occurs at the 
oldest part of the bogs and hence probably represents the con- 
ditions towards which the floating bog is tending. It tends to 
occur also in strips along the contact of mainland and the 
Macrospartinetum, where it begins to merge into swamp, as 
later to be noticed. 
10. THE SPHAGNUM, OR RAISED BOG ASSOCIATION, OR SPHAGNETUM. 
In a few places only, near the margin of the Caricetum, occur 
small areas approximating to the true raised type of bog, con- 
sisting almost entirely of Sphagnum rising above the general 
water level of the basin, with dwarfed heath bushes but no trees, 
and generally showing the characters of Hochmoor which I have 
already described in the first work of this series. Small areas 
of this character also occur in the Sunken Island. But I have 
not tried to work out their relations to other types of bog, and 
the subject remains for future study. 
V. WATER MARGIN FORMATION (NEMATIUM). 
The marsh and bog rivers above the influence of the tide 
everywhere exhibit a dense marginal vegetation (Typha, Spar- 
ganium, Acorus, Lysimachia, Chelone, Dulichium, etc.) differing 
in different parts of marsh or bog, and divisible into three or 
four associations. I have not, however, made any attempt to 
study these in detail. Another association exists on the margins 
of the lakes, and yet another in the bottoms of the aboideaued 
streams. There is also of course a plankton formation in these 
streams, but I have not studied it. 
VI. THE SWAMP FORMATION (HELORGADIUM). 
In most places, at the contact of reclaimed marsh and upland, 
occurs a region of poor drainage in the form of a narrow strip. 
On the wet marsh, along with the Macrospartinetum, this strip is 
45 Not all trees on the bog, however, indicate the flat bog, for many of them, * 
shown by soundings made by engineers of the Misseguash Marsh Co., are growing 
upon islands slightly submerged by the bog. 
