\i>\ri \ i [ONS 01 \<.'i \ 1 1 i 171 



I'IIL: a broad windrow, lifty or perhaps a hundred mih^ Ion- .\eedl 



has described -uch an oc< tu >n the west shore of Lake Mi< hi: 



fullnwi: le from the northeast. In thi- instance, B li' 1 ' 



drift contained nearly four thousand in which 66 per < ent were 



\ >-nit)hins), 20 per cent. Locust ida-. and the remainder mostly 

 beetles (Carabida-. St araba-ida\ ( 'hrysoinelida-, ( 'oceinellida;, etc.), 

 dragon flies, moth-, butterflies (. \nosiii, /'/Vr/.s, et(.) and various 

 1 lemiptera, 1 1\ menoptera and I >iptera. A large proportion of t he insects 

 were aquatic forms, such as Hydropkilus, Cybister, Zaitha, and a species 

 of caddis fly; these had doubtless been carried out by freshets, while the 

 butterflies and dragon flies had been borne out by a strong wind from 

 the northwest, after which all were driven back to the coast by a north- 

 i wind. While some of these insects survived, notably Coccinellidse, 

 Trii -hoptera. Asilidae, Locustidae and Gryllidae, nearly all the rest were 

 dead or dying, including the dragon flies, flies, bumblebees and wasps. 

 Foraging Carabidae were observed in large numbers, also scavengers of 

 the families Staphylinidae, Silphidae and Dermestidae. 



On the seashore and on the shores of the Great Lakes, the salient 

 lures of insect life are essentially the same. Similar species occur in 

 the two places with similar biological relations, on account of the general 

 similarity of environment. 



Origin of the Aquatic Habit. The theory that terrestrial insects 

 have arisen from aquatic species is no longer tenable, for the evidence 

 shows that the terrestrial type is the more primitive. Aquatic insects 

 still retain the terrestrial type of organization, which remains unob- 

 scured by the temporary and comparatively slight adaptations for an 

 aquatic life. Thus, the development of tracheal gills has involved no 

 important modification of the fundamental plan of tracheal respiration. 

 It is significant, moreover, that the most generalized, or most primitive, 

 insects Thysanura are without exception terrestrial. Aquatic in- 

 sects do not constitute a phylogenetic unit, but represent various orders, 

 which are for the most part undoubtedly terrestrial, notwithstanding the 

 fact that a few of these orders (Plecoptera, Ephemerida, Odonata, Tri- 

 choptera) are now wholly aquatic in habit. Adaptations for an aquatic 



tence have arisen independently and often, in the most dive 

 orders of inject 5. 



