AN ECOLOGICAL SURVEY IN THE PORCUPINE MOUNTAINS AND 

 ISLE ROYALE, MICHIGAN. 



A. G. RUTHVEN. 



. CONTENTS. 



Introduction. 



Part I. Porcupine Mountains. 



1. History. 



2. Geology. 



3. General Topography. 



4. Location of Field Stations. 



5. The Biota Considered by Stations. 



6. Summary. 



7. Interpretations and Conclusions. 

 Part II. Isle Royale. 



1. General Geography. 



2. Location of Field Stations. 



3. Biota Considered by Stations. 



4. Summary and Conclusions. 

 Part III. References. 



INTRODUCTION. 



The following report is based upon the results of the University of Mich- 

 igan Museum Expedition to the Northern Peninsula of Michigan. The 

 field work covered a period from July 13 to September 5, 1904. From July 

 13 to August 13 w r as spent in the Porcupine Mountains; the remainder of 

 the time on Isle Royale. After a short reconnaisance, a line was run through 

 that part of the region presenting the greatest variety of habitats, and 

 stations were established on this line at which collecting was done. This 

 plan greatly aided keeping in mind the relation between the physical con- 

 ditions and the biota, as topographic and vegetational features were made 

 the basis for the location of stations. It also made it possible to examine 

 a great variety of conditions and thus obtain representative collections. 



There were six men in the party: Messrs N. A. Wood, Max M. Peet, N. 

 F. Macduff, Otto McCreary, W. A. Maclean, and the writer. Having had 

 some experience in this work, Mr. Macduff assisted the writer in running 

 the line, and while doing this listed the flora of the stations as they were 

 established. Mr. Wood's time was mostly spent in caring for the bird and 

 mammal skins, and in this work he was assisted by Mr. Peet, who, in turn 

 assisted by Mr. Wood, did the trapping. Mr. Peet also spent some time 

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