124 THE CANADIAN ENTOMOLOGIST. 



of the long lists of largely incongruous and incomprehensible names that 

 he is expected to master, it is the utter absence of anything in the system 

 of nomenclature tending to show the relations of various forms to each 

 other, or of varieties to the parent or more abundant form. There is 

 nothing to show at a glance the results of the experience of others and 

 to attain any idea of the true relationship of allied forms. The student 

 must either acquire the knowledge by slow and persevering experiment, or 

 oftentimes forego the acquisition altogether, because time and the rarity 

 of books will not permit him to gain it. We cannot start where others 

 left off, but must follow their paths step by step, only hoping to gain the 

 point they reached soon enough to be able to penetrate a little further. 



Most conspicuously ^s this the case as regards the so-called varieties 

 of variable species. Let a student in England, for instance, take up Mr. 

 Edwards' Catalogue of North American Butterflies, and the first species 

 is listed with three " dimorphic " varieties and one " sub-variety." The 

 theory of their origin is well known, and the facts regarding their appear- 

 ance at certain seasons, but this cannot be learned from the list, and must 

 be gained from various contributions on the subject written at many times 

 and distributed through many books — a comparatively easy task as regards 

 Papilio aj'ax, though less easy were the researches of some species in 

 question conducted by an obscure author and published in some rare 

 book in a foreign language. 



Under the present system Papilio Walshii, Pieris pallida and Grapta 

 umbrosa are designated dimorphic varieties, although no two of them bear 

 the same or similar relations to the species to which they belong. 



It is hardly to be expected that we can arrive at an exact and uni- 

 versally acceptable definition of a species, or that the time will soon come 

 when extremists for the sake of advertisement or other reasons will not 

 persist in declaring accepted species as mere varieties or vice versa, or 

 that such persons will cease to set dictum above experiment ; but it does 

 not seem impossible to adopt some system that shall indicate to a certain 

 extent the relations of many forms, and at the same time elastic enough 

 to be acceptable to all. 



For the purposes of this article, however, I consider it necessary to 

 submit a brief description of what I hold to constitute a species, in the 

 hope that it will substantially agree with the conceptions of others in the 

 main. 



We may define a species as an aggregation of individual forms of life 



