214 THP: CANADIAN ENTOMOLOGIST. 



which the intellect perceives to await accomplishment after a mass of work 

 has been performed in recognising the different kinds. It is hardly 

 advanced by the use of difficult language and the employment of abstruse 

 terms ; for my own part I have always tried to use plain English in the 

 proportion as I seemed really to understand the subject I had in hand, 

 and, without in any way undervaluing the use of proper scientific terms, 

 I think that writings on our Butterflies and Moths are occasionally over- 

 loaded with them, to the detriment of the clear understanding of the 

 subject. We are here facing the one simple problem of the ancestry of 

 our present species and in explaining the existence of the different elements 

 in our fauna, and in trying to sort a few of our leading genera, I have 

 aimed at making the subject clear and attractive, if I could, rather than 

 at expressing myself in a simply technical manner. After the first passion 

 for possessing rare or fine specimens has become blunted, the deeper 

 problems connected with these beautiful and interesting insects obtain a 

 hold on the mind, exercising a more controlling fascination as they lead 

 to wider results. I have been especially struck with the fact that so many 

 leading genera, e.g., Catocala, do not cross the Equator, being confined 

 to the Northern Hemisphere, as also that there is perhaps, on the whole, 

 between the different faunae, from East to West, a greater general resem- 

 blance than from North to South. The hot central Equatorial Region 

 evidently precludes the passage of certain genera, notwithstanding its 

 fecundity in pecuHar forms. And notwithstanding physical barriers, such 

 as oceans and mountains, there seems to have been a transference through 

 changes in climate on isothermal lines around the globe. All these matters 

 are very interesting to speculate upon, and the common mistake of setting 

 up an hypothesis and then treating it five minutes afterwards as a fact as 

 old and well established as the hills, I have myself often, no doubt, fallen 

 into. But I have always relied on my friends to correct my mistakes in 

 print, a matter they have ever promptly attended to, so that, in some 

 sense, I feel quite secure in my statements, which, if they are likely to be 

 true, will be " absorbed," and, if they are not, will be " corrected," myself 

 abused and the public disabused by the operation. 



The subject of geographical distribution is, as I have said, best studied 

 in connection with the topography of the country. In this connection the 

 two principal drainages of the country, the Mississippi and its tributaries, 

 and the chain of the Great Lakes and the St. Lawrence, must be taken 

 into consideration. Valleys and water courses have attracted and furthered 



