MOTHS AND MOTH-CATCHERS. 379 



questions and to matters apparently foreign to the immediate inquiry, 

 that here the subject of the range of North American moths leads us 

 into myth and poetry. For, in finding out that we have species of 

 moths which are found in other continents, the question arises at once, 

 How did they get here ? They could not fly over from Europe, nor 

 could they now cross Behring Strait, with the Arctic climate there 

 existing. Imaginative persons have supposed a submerged Atlantic 

 Continent, which bridged the chasm in a remote geological period. 

 The myth of the Atlantis has been recently furbished up under the 

 facts supplied by the deep-sea soundings of the English steamer Chal- 

 lenger, and the discovery of a plateau at the bottom of the ocean, be- 

 tween North America and Europe. But, if it ever existed, it probably 

 did so at a time before the ancestors of our present moths came into 

 being. 



For a moment, let us leave this matter and look at the question of 

 the affinities of our moths. I have shown, in the " American Journal 

 of Science and Arts," the detailed characters of one family of our 

 moths, the Sphingidce, and what is true of them is true generally. 

 Our moths, in regard to their structural relationship with the moths of 

 the world, fall into three main categories : 1. Those which are peculiar 

 to North America. 2. Those which have their nearest allies in South 

 or tropical America. 3. Those which have their nearest allies in Eu- 

 rope or Northern Asia. 



With these last we have here to deal, and to account for their 

 presence with us. This class falls into two main groups those which 

 are absolutely the same, and those which differ more or less, but clearly 

 reveal their common ancestry. But there exists in these respects every 

 gradation. Some differ so little that there is much dispute as to whether 

 they constitute different " species," and some, again, only differ percep- 

 tibly in certain stages. Others differ a little throughout in all stages, 

 and form what are called " representative species." So, far off in Ari- 

 zona, I have found a species ( Copimamestra occidenta) which " repre- 

 sents " a common European species ( Copimamestra brassicce). What 

 is this little moth, with its big name, doing in Arizona, and how did it 

 get there? With regard to those kinds which are absolutely identical 

 in America and Europe, some have evidently come over through com- 

 merce in historic times. We have found out almost the particular 

 voyage which brought the " Avhite-cabbage butterfly " from England 

 to Quebec, whence the insect has spread over the New England and 

 Middle States, to the great injury of our market-gardeners and cab- 

 bage-growers. But of some the distribution is such that this can not 

 be the explanation of their presence here. Of others it may be doubt- 

 ful. I am inclined to believe that another cabbage-insect, the moth 

 called Pluria ni, has been brought over in this manner. But how 

 about our Arizonian Copimamestra? 



We shall have to leave entomology and go into geology to answer 



