THE CANADIAN ENTOMOLOGIST. 143 



with the corresponding ratios of any other individual existing? There 

 must be a limit to the meaning of these words, or we shall find a genus 

 wherever we find the slightest variation in ultimate structure, that is, a 

 genus for every species, not to say for each individual. An examination 

 of the " Revision " would lead us to suppose that the classification of 

 Butterflies is rapidly drawing to such a condition. When it comes to 

 that, and when each species is the "type" of a distinct genus, what 

 office will remain for genera ? 



But the other or co-ordinate section of the law distinctly bars this 

 manifestly absurd interpretation of the first section, by making species 

 depend, so far as difference of parts is concerned, upon such differences 

 as involve only the " relations and proportions of parts among them- 

 selves." The femero-tibial ratios of five-sixths and six-sixths, for example, 

 are clearly differences of proportion of parts among themselves, and 

 therefore under the law, these differences are not of generic, but only of 

 specific, value. 



That this view accords with usage may be abundantly illustrated in 

 every department of Entomology, not forgetting the writings of Mr. 

 Scudder. In a single genus of Coleoptera, lately revised by Dr. Horn, we 

 find assembled species with " thorax broader than long " and "thorax 

 longer than broad " ; with antennae " short" and antennae " longer than 

 head and thorax''; form "slender," form "broadly oval"; "with 

 wings " and " without wings." In a single genus of Orthoptera Mr. 

 Thomas includes species " with elytra " and " without elytra " ; pronotum 

 cylindrical or carinated ; antennae very long or of ordinary length ; wings 

 absent or present. In Mr. Scudder's Revision of Crickets will be found 

 tables of measurements of individuals of the same species, in which the 

 ratios differ much more than those in the table of Adolescentes, upon 

 which he bases distinctions of genera. In Dr. Packard's Monograph of 

 the Phalaenidae he includes in the genus Thamnonoma species which have 

 the palpi very long, and palpi short ; in Aplodes species which have the 

 first median venule remote from second, and which have the first and 

 second median and posterior discal venules co-originating ; in Tephrosia 

 species which have hind tarsi longer than tibia, and hind tarsi shorter than 

 tibia. In the " Revision" itself, Mr. Scudder admits a variation of 41 

 to 49 joints in the antennae of different species of the genus Argynnis ; 

 it seems, however, that the elastic band which stretches so far would not 

 endure three degrees more of straining to include the antennae of Speyeria 

 with their 52 joints. 



