501 
lakes of northern Minnesota* and in the following year numerous 
Papers along this general line were published both in America 
and abroad. Pieters} adapted the formation classification of Mag- 
nin to an American lake and the writer published a short account 
of two singular floating or anchored atolls of sphagnum which he 
had observed in central Minnesota.{ The general facts are well 
brought together by Warming$ in his recent text-book, although 
with that too frequent disregard of American investigation which 
1s a blemish to so much European compilation. 
Such zonal limnetic formations occur in all parts of the world 
and afford fine examples of this type of distribution. 
At present it is desired to call attention to the tension-line be- 
ern sphagnum moor and the higher forest-clad ridges surround- 
ng such moors as they exist in Minnesota. Sphagnum forma- 
tions with the various attendant plants are commonly designated 
as Muskeag by the woodsmen of Minnesota, and the northern half 
of the State, in particular, furnishes many splendid examples of 
this type of plant association. The smaller muskeags are quite 
S¢nerally round or approximately elliptical in outline, while the 
larger ones, although preserving for the most part rounded out- 
lines, are more irregular in shape. They occur abundantly in the 
Neighborhood of the glacial lakes so characteristically disposed 
throughout the morainic region of Minnesota and are by no means 
confined to the belt of pines, for they may be observed about Min- 
Neapolis, in Chisago county and in the middle western counties of 
the State. Unlike the more ancient lakes of western Ontario and 
the international boundary region between Minnesota and Canada, 
these lakes have the typically rounded form of a glacial basin and 
rarely imitate in outline the long, rock-bound and irregular bodies 
of water so omnipresent in northern Canada. 
The sphagnum moors or muskeags may be regarded as such 
glacial ponds or lakes in process of conversion to forest, and almost 
€very imaginable transition may be found, from open lakes with 
* MacMillan, C, Shore formation of Equisetum limosum, Bot. Gaz. 18: 316 
ey See 
tPieters, A. J. The Plants of Lake St. Clair. Pamph. 1894. 
¢ MacMillan, C. On the Occurrence of Sphagnum Atolls in Central Minnesota. 
Minn. Botan. Studies, 1: 1. 1894. _ 
§ Warming, E. Lehrbuch der Oekologishen Pflanzengeographie, 162. 1896. 
é 
