290 
A. W. LINDSEY 
L The Species Concept. 
The question of the existence or non-existence of species in 
nature is one of such age that some hesitation must be felt in 
attacking it. However, no discussion with which the writer is 
familiar furnishes a satisfactory foundation for a practical sys- 
tem of classification. All treat the species as a thing capable of 
rigid definition, either actual or imaginary, and herein their 
weakness seems to lie. In entering upon a discussion of this 
point it will be well to consider some of the material which it 
concerns. 
In the insects, and in the Lepidoptera perhaps as much as in 
any other order, we are dealing with a highly successful group 
which has ramified considerably in adapting itself to- various 
conditions of environment, yet still includes relatively generalized 
forms. These are capable of becoming modified further in re- 
sponse to changes of the habitats which they now occupy. As 
extreme examples of the specialized types, Feniseca tarquinius 
Fab. and the myrmecophilous Lycaenidae may be cited among 
the Diurnals. Euxoa among the moths and Argynnis, Melitaea 
and Euphydryus are good examples of the more generalized 
genera. It must be clearly understood that all of these forms are 
specialized in some degree, as, of course, all existing Metazoa 
are. 
Such forms as tarquinius may be passed over briefly. It 
seems that everyone should agree in accepting them as well de- 
fined, natural units to which the designation species is properly 
applicable. In the writer's opinion there are many such species 
whose existence as natural entities cannot seriously be ques- 
tioned. Powers applies this idea of species in a sweeping way. 
He states that “The whole spirit of modern biological research 
seems to the writer to demand the conception of species as reali- 
ties, — not all alike, in their reality, of course.”^ 
In contrast to this view, Montgomery says that “in Nature oc- 
cur only individuals, as was clearly pointed out by Lamarck, and 
is generally acknowledged at the present time, species and other 
groups being arbitrary concepts.”- By an extremely rigid and 
inclusive application of this view, it may possibly be regarded as 
^ Studies from the Zool. Lab., U. of Neb., no. 95. Reprinted from the 
American Naturalist, xliii, 1909. 
^ Montgomery, On Phylogenetic Classification, Proc. Acad. Nat. Sci. Phil. 
1902, p. 193. 
