46 THE REPORT OF THE No. 19 



pools, fed by perennial springs — a condition exemplified to-day on the Sevier 

 and Humboldt flats. These are practically extinct as lakes, since they con- 

 tain water only in the winter or after heavy floods, and the shore beetles have 

 been forced to gather about the few small springs that moisten the ground 

 along the borders. 



My proposed explanation, correlating the briefly outlined geological his- 

 t(..ry with the facts offered as to the distribution of the insects, may be sum- 

 marized as follows : — 



1. The shore beetles under consideration are confined to the Great Basin 

 or its immediate borders, and have, in general, no allies in other districts 

 ^rom which they could have been recently developed. This in itself is strong 

 presumptive evidence that they are endemic, not immigrants. 



2. Within the Basin, recent conditions are such that the present dis- 

 tribution cannot possibly be a matter of modern origin. The small lakes now 

 remaining in the Basin are separated by great tracts of arid desert, impassable 

 lo beetles depending on a moist soil for their development and food supply. 

 The nature of these insects is such that they cannot be carried long distances, 

 as eggs or larvae, on the feet of birds or other animals. 



3. Ancient conditions, as shown by the geological history through the 

 Pleistocene, were favorable to the diffusion of shore-loving insects through 

 the Basin, because of the much greater extension of the lakes in those times. 



4. The insect most thoroughly studied, Cicindela echo, is entirely con- 

 fined, in its present range, to the neighborhood of lakes, which from their size 

 and the presence of nearby springs, may be presumed to have lasted in some 

 fcrm from a remote period — even through times of severe drought. Other 

 littoral forms follow the same general law, though some of them are less sen- 

 sitive to local conditions. 



From these facts, I think we can come to but one conclusion — the beetles 

 under consideration are types that have inhabited the Basin during the Pleis- 

 tocene times when the shores of the great lakes stretched over hundreds of 

 miles of what are now desert sands. As the lakes shrunk during times of 

 drought, the insects followed the retreating beaches. Those which attached 

 themselves to bodies of sufficient size or permanence were able to sustain their 

 specific existence, while such as were dwelling on the edges of pools of a tran- 

 sient nature were exterminated altogether. Thus we have the phenomenon 

 of discontinuous distribution, presented not by one species alone but by an 

 entire assemblage. 



The Chairman, Dr. Fletcher, expressed in happy terms the thanks of the 

 audience to Prof. Wickham, for his interesting address and his kindness in 

 travelling so far to attend the annual meeting of the Society. 



SECOND DAY'S SESSION. 



The Entomological Society resumed its meetings at 10.30 o'clock, a.m., 

 the President, Prof. Lochhead, occupying the chair. The first order of busi- 

 ness was the election of officers for the year 1904-5, which resulted as shewn 

 on page two. 



Dr. Fletcher moved, seconded by Mr. G. E. Fisher, "that popular articles 

 should be published in the Canadian Entomologist next year, at least two 

 pages per month, or more at the discretion of the Editor." After some 

 remarks by the mover and seconder and also by the Editor in support of the 

 resolution, it was unanimously adopted. 



