56 PSYCHE [April 



identity, as species are understood by the present-day entomologist. If a foreigner 

 lands in Quebec, Canada, or Baltimore, Maryland, it will sooner or later find its 

 way to Buffalo, New York, and westward along the shores of Lake Erie, into the 

 great level country beyond the Appalachians, feeding probably, but not necessarily, 

 on the same food plants that it ate in its home in the eastern hemisphere. 



In the eighteenth century it was thought sufficient for naturalists to state that 

 such and such species inhabited North America. In the nineteenth century we 

 decided that we must state whether a species was found in Connecticut or Rhode 

 Island, but it would suffice if the statement were made that it was found in Illinois, 

 notwithstanding that there is more difference between the insect fauna of northern 

 and southern Illinois than there is between the latter state and Ohio. In the 

 beginning of the twentieth century we have come to the conclusion that labels, 

 giving the states only, without more explicit information as to localities from which 

 the specimens to which they are attached have been obtained, are of little value to 

 the student of morphology, or in tracing out the distribution of species ; nevertheless 

 we cannot entirely overcome the old prejudice relative to political lines forming 

 biological boundaries. At present, there is nothing for the American entomologist 

 beyond the Rio Grande River. Of course we know that there are insects there, 

 but, by an unwritten law of our own construction, we prohibit ourselves from know- 

 ing much of their identity or affinities to species found on our own side of that 

 river. Mexican and Central American species are either excluded from our col- 

 lections, or, if admitted, are crowded down in the corners and labeled, if indeed at 

 all, as foreign ! Thus the most interesting territory in the western hemisphere and 

 what to us is really the most significant, as from out of it whole genera of our insect 

 fauna have been evolved, remains almost a terra incognita. Let me illustrate. A 

 phytophagous species starts from South America on its way northward. Even 

 while passing through Central America as well as through Mexico, it is obliged to ' 

 encounter a diversity of climate, elevation, and food supply. The species in adapt- 

 ing itself to these modifying influences becomes shattered as it were and the frag- 

 ments are found in Texas, in New Mexico, Arizona, and California. We find these 

 and with the least possible delay, and with no knowledge of their affinities or, in 

 many cases, developmental stages, they are described as so many species and 

 added to our checklists. Can stability in our nomenclature be expected as long as 

 these conditions continue ? These same influences are at work in California, and 

 we can see their effects plainly enough there, though both conditions and results 

 are only modifications of what is probably going on farther to the south, and they 

 are of proportionally less value in aiding us to solve our problems in biology and 

 nomenclature. Other modified influences, similar to those at work in California, 

 may be noted in connection with the Antillean and Boreal trends of diffusion, but 



