90 OF WASHINGTON, VOLUME XII, 1910. 



If we consider the neuropterous family Hemerobiida? we 

 reach other conclusions. The genus Hemerobius is a northern 

 one and common in Europe and the northern United States. 

 But the species from the Western States are not more like the 

 European than the eastern forms; indeed, the species most 

 abundant in the East is a common European species. The 

 genus Micromus in our fauna contains two different elements; 

 one of the northern species occurring in mountainous regions 

 is the same, or closely related to certain European forms; 

 the other element represents species derived from the Alicro- 

 miis species that occur in all tropical countries; these are much 

 more widely spread and much more abundant than the north- 

 ern forms, which are rare and local. Our most striking heme- 

 robiid is Polystoechotes, fully as abundant in the Northwest 

 as anywhere, yet there is no such form in Europe; they have 

 Osmylns fairl3 7 common, while we have none. Their Drepa- 

 ucpteryx is most closely related to our Lomamyia, which is of 

 southern distribution; their D ilar occurs with us only in the 

 Southeastern States. The genus Sympherobius is of similar 

 distribution. This exhibits another point, the similarity be- 

 tween the Southern part of the United States and Southern 

 Europe. Taken as a whole the hemerobiid fauna of Europe is 

 more like that of the Eastern than the Western States. 



If we examine the distribution of the caddice flies of the fam- 

 ily Limnephilidae, we see that our entire limnephilid fauna is 

 closely similar to that of Europe. There are no southern 

 forms of these to spread up over the south or Atlantic coast. 

 Yet in the United States we can readily detect differences be- 

 tween eastern and western faunas. While there are many 

 that are of northern distribution, the eastern fauna as a whole 

 has more resemblance to the central and southern European 

 forms, while the western and Pacific Northwest is more re- 

 lated to the north of Europe and to Russia and Siberia. 



None of these families that I have mentioned are dependent 

 upon vegetation for distribution; most of the species are pre- 

 daceous; but the habits of each group are quite different from 

 the others. 



The southern extension of northern species varies with the 

 family; in Micromus and some northern Epeiras, they extend 

 across the country, usually in the high mountains. With 

 others, as Phalaiightm cincrciim, they extend southward 

 into western North Carolina and into western New Mex- 

 ico. The northern extension of southern species is also vari- 

 able; in some cases, as in Mantispa and LatJirodcclcs, they go 

 up into New England and Canada; with most species, how- 

 ever, the range is less extensive. 



