KCOLOGY OP ISLE ROYALE. 163 



stage, with a diversified vegetation, we may expect tlie greatest variety 

 of beetles. From sucli relations as these it follows that a knowledge 

 of plaint succession will furnish a very important basis for the study 

 of beetle succession. 



While these remiarks have been primarily intended for beetles, it 

 is equally evident that they have a much more extended application 

 to other pla,nt feeding insects and certain, other invertebrates as well. 



IT. The General Characteristics of the North American Beetle Fauna. 



In attempting to form some idea of the general faunal affinities of 

 the Isle Royale beetle fauna, the literature was searched for a gen- 

 eral account of the distribution of North American beetles. As no 

 recent comprehensive account of the subject could be found, various 

 general statements and generalizations were compiled. On account 

 of their scattered occurrence in the literature and their value and 

 suggestiveness to students of other groups of insects, it has been 

 thought desirable to assemble and publish them. An effort has been 

 made to quote only the more important statements. Several of the 

 older statements by LeConte, before he accepted the theory of evolu- 

 tion, are omitted. A similar selection has also' been exercised in the 

 case of some other writings. The main aim has been to bring to- 

 gether the most comprehensive generalizations which have been made 

 upon our beetle fauna, so that they may have greater utility, further 

 extension, and revision. Supplementary data from other groups of 

 insects has largely been omitted, although this should be given due 

 weight in a comprehensive study of this subject. The references should 

 'be consulted in connection with the compiled abstracts. 



1. Compiled Generalizations on the Fauna. 



Carpenter, W. L. 1875, pp. 539-542: "The principal and most inter- 

 esting result obtained from the study of this collection, is the demon- 

 stration of the fact that tlie alpine insect-fauna of the Rocky Moun- 

 tains, is nearly identical with that of Mount Washington (New 

 Hampshire), Labrador, and Alaska; and that insects which are found 

 upon mountains at great elevations will likely occur in a much higher 

 latitude at a less elevation. 



"Insect-life, with the exception of the grass-hoppers, is more abund- 

 ant in the foot-hills than the plains near the foot of the mountains. 

 An altitude of about seven thousand feet appeared to produce the 

 greatest variety of species." p. 540. 



Gockerell, T. D. A. 1893, pp. 305, 306, 309, 310-311, 312, 313-314, 

 315, 316, 317, 319-320-322. 



"The insect fauna of the mid-alpine zone of Custer County [Colorado] pre- 

 sents some elements which are sufficiently diverse; but taken as a whole, it 

 is a natural fauna, belonging to a well-defined region, and hence available 

 for comparison with other like faunae. It is, indeed, truly characteristic of 

 the mid-alpine, that besides its ordinary elements, it contains species coming 

 up from the sub-alpine, and down from the high alpine; but although it thus 

 happens that Junonia coenia and Parnassius smintheus have been taken in 

 the same zone, it does not follow that either are truly characteristic of It, 

 or that they belong to the same fauna. All faunal lists contain such excep- 



