42 THE REPORT OF THE No. 19 



carried on without mucii expense ; and it is a study which, perhaps better than 

 most others, gives the student a conception of the wonderful inter-relationship 

 of organisms. Let us hasten the time , therefore, when the teachers in our 

 schools will be able to use the abundance of insect life about them in the edu- 

 cation of their pupils. 



After the conclusion of the President's Address, Professor H. F. Wick- 

 1 {.m, of the State University of Iowa, Iowa City, one of the Honorary Mem- 

 bers of the Entomological Society of Ontario, gave a very interesting address, 

 illustrated with a large number of lantern slides, made from photographs 

 which he had taken at the various localities referred to. The following is 

 au abstract of his address : 



INSECT DISTRIBUTION IN THE GREAT BASIN CONSIDERED IN 

 THE LIGHT OF ITS GEOLOGICAL HISTORY. 



By H. F. Wickham, Iowa City, Iowa. 



In the discussion of the problem of the present distribution of ani- 

 mals on the earth's surface, the influence of the better marked features in the 

 geological history have been widely recognized. It is well known, for in- 

 stance, that an island lying far out to sea and separated from other land areas 

 f<~r vast periods of time will be inhabited by an assemblage of animals quite 

 distinct from those of other regions — and in general, it may be said that the 

 length of time during which this island has been thus separated, and the com- 

 pleteness of its isolation are the principal determining factors in the develop- 

 ment of a peculiar fauna. Temperature, climate, chemical nature of soil 

 and water, together with numberless other physical conditions, all conspire 

 to work on organisms with the result of constant, though often slow change — 

 until in the course of numberless generations the members of the isolated 

 colony present an assemblage of characters quite different from those pos- 

 sessed by their relatives elsewhere. The occurrence of beetles on the high 

 peaks of the Rocky Mountains, and on the summits of Mounts Washington 

 and Katahdin, whose nearest allies are characteristic of the cold plains of 

 the far north, has been explained in the light of our knowledge of the great 

 s^outhward movement of the ice in remote times. The ancestors of these 

 stranded insects fled to the south in front of the advance of the tremendous 

 glaciers. When these finally melted, their borders, retreating northward, 

 were followed by the beetles which flourished in the cool climate of the edge 

 of the ice-sheet; but some of the indivdiuals sought to escape the ever in- 

 creasing heat by ascending the mountains. Where these were high enough 

 to furnish proper climatic conditions for the colony thus formed, communi- 

 ties have been carried through to the present day, and the collector may find 

 on the summit of the highest Rockies the identical species that he catches on 

 the frozen shores of Labrador, though the intervening valleys of the United 

 States and southern Canada will not furnish him a single specimen. 



Another well known characteristic of insect life, is the tendency of suc- 

 cessful species — those which are in such perfect harmony with their sur- 

 roundings that the increase in number is very rapid — to spread, and to in- 

 vade new territory. Where this spread is natural, that is to say, not depend- 

 ent on human agency, it usually takes place along definite lines. These lines 

 aie determined by various conditions, depending on the nature o± the insect, 

 as well as on the country which it is invading. Some are very sensitive to 



