THE CANADIAN ENTOMOLOGIST. 237 



that these general ideas as to the origin of our fauna will more and more 

 come to be regarded as probably true, and that I have given them a proper 

 scientific basis. 



As we go southward, the Canadian fauna gradually absorbs southern 

 elements in its character. Certain genera, which are plentifully repre- 

 sented in the West Indies, appear in single species ; as, for instance, the 

 brightly colored, clear spotted, arctic form, Zygaenidce. Occasionally, at 

 least, Cosjtiosoma omphale occurs in New Jersey ; it is not rare in South 

 Carolina ; I have taken it, flying in the daytime, in Alabama. Again the 

 larger species of CeratocampincB, such as Cithcronia and Sphingicampa. 

 become more plentiful in individuals in the Middle and Southern States, 

 There is a change in the character of the Noctuidce ; certain genera of the 

 Nonfasciatce, such as Orthosia and allies, LitJwphaiie, etc., gradually dis- 

 appear, and the genera of the Fasciatce, such as Homoptera, Pleonectyp- 

 tera, Poaphiia, Remigia, Homopyralis, etc., become more plentiful. 

 Again, as we go westward, the Heliothians appear in more numerous 

 forms of genera and species, and, in Colorado and California, are quite 

 important components of the Noctuidce. But, as a whole, we have a 

 fauna of moths homogenous in general character until, on the Atlantic 

 side, we strike the tropical colony in Florida, and, on the west, we meet 

 the Mexican fauna in Texas and the South-west Territories. Labradorian 

 and Arctic forms we meet again on the summits of the White Mountains 

 in the east, and on the Rocky Mountains and parallel ranges in the west. 

 The local lists which have appeared of late, and the con;ipilation of which 

 is most laudable work for entomologists in all parts of the country, bear 

 out this general view. The replacement and change of species is a very 

 gradual one ; striking differences will be called out by the comparison of 

 localities separated by mountain ranges. If the student will bear in mind 

 the different elements which go to make up our fauna, and which are here 

 superficially discussed and indicated, he will arrive at some comprehen- 

 sion of the relationship which our fauna bears to that of Europe, Northern 

 Asia and South America, and, in time, its true distinguishing features can 

 be fully grasped. My own principal satisfaction, during late years, has 

 arisen from a slightly increased apprehension of the importance of the 

 problems of geographical distribution, and how they inay have been influ- 

 enced and brought about. All this will come clearly to light when large 

 collections shall have been brought together from all principal points 



