4 BOTANICAL GAZETTE [JANUARY 
southwestern end of the island. In respect to the vegetation the 
results of this expedition consist in scattered ecological notes and a 
list of plants including only 91 species (49). 
The second party, headed by Dr. C. C. Apams, devoted all its 
time (about six weeks) to Isle Royale, and the resulting report is 
incorporated in a volume of more than 400 pages (4). The botani- 
cal work was done by Hott (33), whose report comprises a tén- 
page.account of the plant societies, and an annotated list of lichens, 
mosses, ferns, and seed plants, including 364 species. There is 
also much of ecological value to be found in the sections by ADAMS, 
and the report by GLEASON upon the ecology of the invertebrates 
(29). 
Two papers by the present writer (12, 12@) should also be men- 
tioned, as they were suggested by observations upon Isle Royale. 
TOPOGRAPHY AND PHYSIOGRAPHIC HISTORY 
Isle Royale is situated in the northwestern part of Lake Superior 
in lat. 48° N., long. 89° W., about 25 km. distant from Thunder 
Cape, which is the nearest point of the Canadian mainland. The 
island is elongated, extending northeast and southwest, and its 
dimensions are 72 km. by 14 km. at the widest part. It is formed 
of several parallel ridges which are made by the resistant centers of 
successive outcrops of a series of Keweenawan lava flows. These 
dip southeastward at angles varying from 5° to 40°. The southeast 
slopes of the ridges are gentle, corresponding with the dip of the 
beds, while the northwest faces are steep and broken, often pre- 
cipitous. Several of them extend into the lake at either end of 
the island as promontories or rows of small islands (fig..1). The 
largest, the Greenstone Range, stretches the whole length of the 
island, and is continued northeastward in Passage Island and Gull 
Rocks. At several points it reaches an altitude of more than 150 m. 
above the lake level. Between the ridges are narrow valleys, 
corresponding with the less resistant peripheral portions of the 
flows and the sedimentary layers that are interbedded with them. 
These contain many lakes, and where submerged at the ends of the 
island form narrow fiord-like harbors and channels. The drainage 
is well adjusted to structure, the streams flowing along the strike 
