OF WASHINGTON. 189 
since attracted attention, and various explanations are offered for it. 
It has been said that there is some ancient and obscure natural law 
according to which the dispersion of animals and plants in the 
northern hemisphere takes place in the direction of from east to 
west. Others restrict the working of this law to the continents 
adjacent to the Atlantic ocean, supporting their theory by the geo- 
graphical configuration of the continents Kurope, with its un- 
paralleled development of coast line, being naturally the country 
of exportation. Another apparently more plausible explanation is 
that the fauna and flora of the so-called New World (which is in 
reality the oldest continent.Lare so weak and degenerated that they 
cannot compete with the younger' and more vigorous flora and 
fauna of the so-called Old World. Others have added that after 
all there is a climatic difference between Europe and North Amer- 
ica which favors only the introduction of Old World species into 
North America. I must confess that I have not become convinced 
of the force of these explanations when applied to the introduc- 
tion of insects. Some of our native dung-beetles of the genus 
Atccnius occur all over the continent, .from Canada to Patagonia, 
and exhibit, therefore, a considerable power of adaptation as to 
climate. Moreover, these species live in all stages, not only in 
dung but also in rich soil in other words, under conditions most 
favorable for exportation. How these species can be considered 
as less vigorous than the Old World species is difficult to under- 
stand. Still they have never been introduced into Europe. Our 
Stelidotas, certain Epurasas, etc., which are so frequently found 
on apples and other fruits packed in barrels or boxes, have never 
been found in Europe. Trogoderma tarsale, of the family Der- 
mestidce, is only too well known to most of us as the most annoy- 
ing museum pest. It not only infests dried insects, but also skins 
of stuffed animals, and with such objects it must have been trans- 
ported to Europe, not only once but frequently, and must have 
been found at least at many places in Europe. Still, one can hunt 
through the whole coleopterological literature of Europe without 
finding any notice of its occurrence in that country. This in- 
stance appears to be quite inexplicable, unless it turns out from 
comparison of specimens that Trogoderma tar sale is identical 
with a European species ( T. ornatum). 
Still, our American fauna has furnished at least a few contribu- 
