—44— 



is this steep-flanked ravine, its floor from sixty to seventy feet lower than the 

 surrounding upland and in which occur the "Big Springs", sources of Carp 

 Creek. The Gorge is situated about a mile from the Biological Station. 



The Streams.— There are a number of these, varying in size, in flow and 

 swiftness, in temperature, and in character of banks, but all agree in having a 

 sandy, gravelly or muddy floor, rocky stream beds being conspicuously lacking 

 in this region. 



Coniferous Forest Swamps. — Low wet grounds commonly are wooded main- 

 ly with white cedar and black spruce. A typical swamp of this kind is Reese 's 

 Bog, about a mile from the Station, which occupies a strip perhaps two miles 

 long and up to half a mile wide along the northern shore of Burt Lake. The 

 tamarack predominates locally in wooded swamps, more especially in areas 

 that have been burned over. 



Open Marshy Swamps. — These are characterized typically by the abundance 

 of sedges and grasses and the scarcity of sphagnums. Commonly they are peri- 

 odic swamps and the underlying mineral soil is but sparingly covered with organic 



debris. 



Open Sphagnum Bogs. — These are of the familiar sort, characterized by the 

 abundance of sphagnum mosses and ericaceous shrubs and by the presence of 

 a deep peaty substratum. 



In the detailed list which follows, generally speaking, the habitat relations 

 of each species are indicated, together with its comparative frequency in the region 

 under consideration. For the majority of species definite stations are cited, 

 these stations being represented by specimens in the Herbarium of Yale Univer- 

 sity and most of them also by duplicate specimens in the Herbaria of the New 

 York Botanical Garden and of the University of Michigan. For species recorded 

 as "common", however, as well as for some of those recorded as "frequent", 

 specific stations are not given: in all such cases a definite "Douglas Lake" 

 station can be assumed. Except where otherwise noted, all records are based on 

 the writer 's collections. Of the localities mentioned, aside from those that can be 

 found on any good map of this region or for which the name given is self-explan- 

 atory, Fontinalis Run, Reese's Bog, and Colonial Point adjoin Burt Lake; North 

 and South Fishtail, Grapevine Point, Polypody Bluff, Bryant's, Fairy Island, 

 and Pine Point border on Douglas Lake; while Lancaster, Munro, Vincent and 

 Mud Lakes, together with the various "bogs", are all in this immediate vicinity. 

 For assistance in the determination of material grateful acknowledgment 

 is made to Mrs. E. G. Britton, Dr. A. L. Andrews, Mons. G. Dismier, Dr. A. W. 

 Evans, Dr. A. J. Grout, and Mr. R. S. Williams. 



Maichantiaceae 



Conocephalum conicum (L.) Dumort. Common along overhanging banks 

 of streams in moist woods. 



Marchantia polymorpha L. Common on wet ground in the open, but 

 especially in swamps that have recently been burned over. 



