1920] TAYLOR— SUCCESSION OF MOSSES 481 



Cowles at Turkey Run, Indiana, where it is a common species aid- 

 ing in the tufa formation in the waters of similar mineral springs (i i) . 

 Pond and lake successions. — The pond and lake successions 

 may be classed in two general groups based on the ecological 

 development. The early successions are represented in the 

 Chicago region by two subdivisions, the pine pannes examined at 

 Miller and the lagoons of Buffington and Long Lake, Indiana. 

 The later successions may be found in the swamp forests at Wilhelm 

 and Furnessville, Indiana, and Thornton, Illinois, and the bogs at 

 Mineral Springs and Hillside, Indiana. 



Early stages of pond succession. — Pine pannes. — The pine 

 pannes are depressions among the dunes, so low that water which 

 seeps through the sand from the lake, or in this case partly from 

 the Grand Calumet River, reaches the surface or even may rise 

 above it. Some of the depressions may be quite dry during the 

 summer; others may have sufficient water to withstand ordinary 

 summer drought, and remain wet throughout the year. Surround- 

 ing the more or less circular body of water in the center of the 

 larger depressions is a border of pines of the same species as pre- 

 viously mentioned for the pine dunes. As a general rule we do 

 not find a typical pond flora even in the center, probably because 

 the quantity of water may be subject to great variation during the 

 year. Sedges and marsh grasses are common, especially near the 

 margin. Only one species of moss forms an extensive growth, 

 • namely, Gampylium stellatum. It may be entirely submerged in 

 the shallow water, but seems to thrive equally well along the edge 

 where it emerges, and, as a relic from a former hydrophytic condi- 

 tion, may even be found on the higher ground at the edge of the 

 tree zone. It is not a floating species in the pannes and is not 

 found in deep water, yet it is the same species which forms much 

 of the substratum of the floating islands in the lagoons at Buf- 

 fington. While it cannot be considered as a tufa former, it aids 

 materially in filling up such depressions. On the higher land 

 among the trees other mosses are either absent or, if present, are 

 of the same species as already given for the early pine dunes. 



Lagoons. — The lagoons at Buffington have been described in 

 the first part of this paper. The water is much deeper than in 



