346 ENTOMOLOGY 



Corydalis. Sialid characters, indeed, appear in the oldest fossils known, 

 and are strongly manifest throughout the fossil series, though among 

 recent insects Sialidae occupy only a subordinate place. Strange to say, 

 few aquatic insects have been found in this ancient lake basin. 



Fossil butterflies are among the greatest rarities, only seventeen 



being known; yet Florissant has 

 contributed eight of these, a few of 

 which are marvelously well pre- 

 served (Fig. 308), as appears from 

 Scudder's figures. Two of the 

 Florissant specimens belong to 

 Libytheinae, a group . now scantily 

 represented, though widely distri- 

 buted over the earth. The group 

 is structurally an archaic one, and 

 FIG. 308. Prodryas persephone, a fossil its recent members (forming only 



butterfly from. Colorado. Natural size. . , . -, j ,., ,.,, , ., , 



After SCUDDER. one eight-hundredth of the described 



species of butterflies) are doubtless 

 relicts. 



Taken as a whole, the insect facies of Tertiary times was apparently 

 much the same as at present. The Florissant fauna and flora indicate, 

 however, . a former climate in Colorado as warm as the present climate 

 of Georgia. 



Quaternary. The interglacial clays of Toronto, Ontario, have yielded 

 fragments of the skeletons of beetles to the extent of several hundred 

 specimens, about one third of which (chiefly elytra) were sufficiently 

 complete or characteristic to be identified by Dr. Scudder, who found in 

 all 76 species of beetles, representing 8 families, chiefly Carabidae and 

 Staphylinidae. All these interglacial beetles are referable to recent 

 genera, but none of them to recent species, though the differences 

 between the interglacial species and their recent allies are very slight. 

 As a whole, these species "indicate a climate closely resembling that of 



Ontario to-day, or perhaps a slightly colder one One cannot 



fail, also, to notice that a large number of the allies of the interglacial 

 forms are recorded from the Pacific coast." (Scudder.) The writer, 

 who has studied these specimens, has been impressed most by their 

 likeness to modern species. It is indeed remarkable that so little 

 specific differentiation has occurred in these beetles since the inter- 

 glacial epoch certainly ten thousand and possibly two to three hundred 

 thousand years ago. 



