Evolution and Taxonomy 93 



If the scales of any of the more generalized moths be ex- 

 amined, thej' will be found to be long and narrow and scattered 

 irregularly over the surface of the wing. On the other hand 

 in the more specialized members of the order, as in most 

 butterflies, the scales are much less hair-like, being short and 

 broad ; and they are arranged in regular overlapping rows. 

 Evidently both the form of the scales and their arrangement 

 upon the wing offer indications as to the degree of divergence 

 from a primitive type of the insect bearing them. 



More than this I am convinced that in some cases at least 

 the form of the scales is characteristic of a particular line of 

 development. One can determine, for example, without any 

 doubt whether a moth belongs to the I^asiocampidae or not by 

 merely examining the scales of the wings. 



I was impressed with the taxonomic value of the scales very 

 soon after I began the systematic study of the I,epidoptera ac- 

 cording to the method outlined in this essay. But the time 

 at my disposal would not admit of my investigating this part 

 of the problem in a satisfactory manner ; and at my request 

 the investigation has been undertaken by my colleague Pro- 

 fessor V. I<. Kellogg of the Iceland Stanford Junior University. 



Professor Kellogg is preparing an elaborate paper on this 

 subject, which will be published soon after the appearance of 

 the volume containing this one. 



While the chief object which I have had before me is the 

 indication of a method of taxonomic work, I hope this essay 

 will be of value to entomologists in hastening the adoption of 

 a uniform nomenclature of the parts of the wings of insects, 

 and thus make easier the study of the relation of the different 

 orders of insects to each other. In order that this nomencla- 

 ture may be more complete I propose the following method 

 of naming the cells of the wing ; for we have as yet no 

 system that is of general application. 



The method I propose is, briefly, to designate each cell by 

 the name or number of the vein that forms its front margin 

 when the wings are spread. 



The application of this system to the I^epidoptera is indi- 

 cated by Figure 33. 



