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XL On the Genus Colias. 

 By H. J. Elwes, F.Z.S., F.L.S. 



[Read August 4th, 1880.] 



Having recently had occasion to arrange the species of^the 

 Genus Colias contained in Messrs. Godman and Salvini's 

 magnificent collection, and having found, as others have 

 done before me, that the genus is an exceedingly difficult 

 one, I offer a few notes on some of the species, in the 

 hope that they may be useful to those who are not disposed 

 to recognise every slight variety as a distinct species. 



It is a very compact and homogeneous genus, containing, 

 according to the views of some lepidopterists, a large number 

 of species ; but I venture to think that time will prove that 

 many of these are but local varieties, and cannot possibly 

 be distinguished from each other with certainty. The best 

 proof of this is that if a large number of Colias from all 

 parts of the world are mixed together, it is, in many cases, 

 impossible to arrange them again under their supposed 

 species. Some may be distinguished in the male sex only, 

 others in the female. Many can only be referred to their 

 right places when the locality from which they come is 

 known, and as most of the local forms are variable, there 

 Avill always remain, even when the habitat is known, 

 specimens which cannot be named with certainty. 



This applies specially to the North American forms, of 

 which many have been recently described by Mr. Edwards and 

 others ; and as few or no specimens of some of these are to 

 be found in European cabinets — or if they exist cannot be 

 recognised — I can only follow Mr. Herman Strecker, whose 

 catalogue of North American butterflies, recently published, 

 seems to be drawn up with broader and more scientific 

 views as to the value of slight variations than Mr. Edwards' 

 catalogue, which appeared a year sooner. 



Russian and German naturalists also have described 

 many supposed species, which further investigations have 

 proved to be identical with, or very slightly varying from, 

 those now accepted ; and I am convinced that a future 



TRANS. ENT. SOC. 1880. — PART III. (oCT.) 



