March, I9I2.] LeNG : ClCINDELID^ IN EASTERN NORTH AMERICA. 9 



During the glacial period everything on the Atlantic coast north 

 of this latitude was covered with ice and snow and the climate imme- 

 diately south of us must have been materially colder. Previous to the 

 glacial period an opposite condition prevailed ; the climate far to the 

 north was temperate, forests flourished north of the present Alaska, 

 and a comparatively warm British America was connected with an 

 equally warm Siberia. The accidents of tide and wind and current, 

 of elevation or subsidence of coastal plains, even of volcanic eruption 

 are as nothing compared with the accidents to which tiger beetles 

 were exposed before and during the glacial period. One can conceive 

 of nothing to prevent the distribution of species from one continent 

 to the other while they were connected. Even now we hear of 

 circumpolar species, then each and every species may have been cir- 

 cumpolar in its distribution, displaying only such varieties from the 

 opposite ends of its range as we find now in the traiiqiicbarica of 

 eastern and Pacific America. Then came the ice age, covering the 

 north land with ice and snow, leaving possibly an always unglaciated 

 area, as indicated in the map of Salisbury and Chamberlain, in 

 Wisconsin extending northward into British America and perhaps 

 other smaller unglaciated areas elsewhere, with alternating periods 

 of extreme cold and milder climate, driving the tiger beetles south, 

 then allowing them to return, then driving them south again, 

 over and over again. At least three such alternations are traced by 

 geologists. Need we be surprised if some species were exterminated 

 and others nearly so? Would not naturally some survive the ice age 

 as isolated remnants of a once far spreading species? And with the 

 barriers I have indicated to their dispersal might they not to this day 

 exist as isolated colonies? Compare with this theory the actual dis- 

 tribution of ancocisconcnsis, White Mountains of New Hampshire, 

 De Bruce in Sullivan Co., N. Y., Cazenovia Creek near Buffalo, N. Y., 

 and the mountains of West Virginia, four isolated stations with no 

 localities known between. Compare marginipennis living on the 

 montainous banks of the Delaware River at Callicoon, N. Y., and 

 the similar banks of the Susquehanna River in Pennsylvania. Com- 

 pare lepida found in Manitoba, Nebraska and vicinity of New York 

 City. All understandable as remnants of glacier tormented species 

 but on no other theory that I have ever heard advanced. 



Origin.- — I do not mean to imply that for all the species men- 



