252 ENTOMOLOGICAL NEWS. [Sept., 'o6 



some value, for it embraces 58 per cent, of all the Algonquin 

 species. 



These are exceedingly interesting facts, and although the 

 data are far from complete, it is evident that they point deci- 

 sively toward the solution of the problem of the origin of the 

 Algonquin insect fauna we are considering. For the Canadian 

 series come from what Transeau describes (pp. 884, 885), as 

 the "northeastern conifer forest centre," with a ratio of no 

 or more percentage of humidity, and the second series from the 

 regions he describes as "open forests," "oak openings," "dense 

 forests on low grounds" and the "decidious forest centre" hav- 

 ing a ratio of less than no per cent, of rainfall to evaporation. 



The situation of Algonquin in northern Illinois, as situated 

 on the map given by Transeau, confirms the ideas stated above. 

 For the locality is near the northern edge of the ' ' decidious 

 forest centre," and also near the southern edge of the "north- 

 eastern conifer forest " in Wisconsin. This statement is 

 emphasized by the fact that a genuine cedar swamp exists ten 

 miles south of Algonquin, near Elgin, which is as characteris- 

 tic as are the cedar swamps of northern Michigan or Wisconsin. 



The views of Transeau, as given above, confirm the ideas 

 earlier advanced by Mr. Chas. C. Adams, in a very interesting 

 and valuable paper, ' ' On Post Glacial Dispersal of the North 

 American Biota," published in the Biological Bulletin in 1905 ; 

 a map on page 57 of that paper very clearly shows how his 

 second biotic type from the north, and the fourth biotic type 

 from the south of the Ohio River, on the retreat of the Wis- 

 consin glacial ice sheet, would naturally meet in the region of 

 northern Illinois, and establish a fauna and flora, having many 

 characters in common with those of the northeast and south- 

 east. The boreal and austral types would mingle and find in 

 northern Illinois a common ground, and the fauna and flora 

 would necessarily show evidences of this double derivation. 



It is to be hoped that sufficient data will be accumulated in 

 a few years to enable the conclusions arrived at in this paper 

 to be thoroughly investigated. A list of the hosts of the 

 Algonquin parasitic insects given in this series of papers, and 

 of the food plants of these hosts, would enable us to clear up 

 some of the points at issue. This, and the analysis of many 



