Genus 151 



the personal opinion of the naturalist who uses them, 

 so "genus" is a conception which differs in extent 

 and value in the minds of different students. In 

 markings Cyaniris is readily distinguishable from 

 Polyommatus, but in structure it is hard to find 

 much difference between the two, except that the 

 wings of the former are somewhat the more rounded 

 in outline. On account of this similarity in structure 

 some naturalists would refuse generic rank to Cyaniris, 

 and either call our last-described insect Polyommatus 

 argioltis, or, degrading Cyaniris to the level of a " sub- 

 genus," would write the name Polyommatus {Cyaniris^ 

 argiolus. 



As an insect universally admitted to belong to a 

 genus distinct from Polyommatus, we may take the 

 copper-coloured butterfly Chrysophamis phloeas} men- 

 tioned before in this chapter. 



If the scales be removed from the wings of one of 

 the blue butterflies, so as to render the neuration 

 clearly visible, it is found that the first branch of the 

 median nervure in the forewing (fig. 87 ivi) is 

 separate from the radial system (fig. 87 iii), while 

 the space (discoidal cell) near the base of the wing 

 between the radial (iii) and the cubital (v) nervures 



^ In precise zoological nomenclature, the name of the author 

 who first described a species is written after the specific name 

 (usually in an abbreviated form), as Chrysophanus phlaat (Linn.). 

 The parenthesis indicates that Linne, who named the species, re- 

 ferred it to a comprehensive genus (^Papilio), whence Chrysophanus 

 was afterwards separated. Where a species has not been removed 

 from the genus adopted by its original describer, the bracket is not 

 used, as Forficula auricuLria, Linn. A second or later name given to 

 a species is known as a synonym, and the tracing of synonymy is 

 often a laborious task. The specific name aUxis, for example, has 

 been applied both to Polyommatus astrarche (by Von Rottemburg) and 

 to P. icarus (by Denis and Schilfermiiller). Consequently the name 

 alexis without an authority conveys no certain idea which of the two 

 species is meant. For the latest rules of zoological nomenclature, 

 see (94). 



