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XV. Heterocerous Lepidoptera collected in Chili hy 

 Thomas Edmonds, Esq. By Akthue G. Butler, 

 F.L.S., F.Z.S., &c. 



[Eead June 7th, 1882.] 



Part III.— GEOMETRITES. 

 Plate XVI. 



There is great difficulty in deciding how many species 

 of Geometrites exist in this collection, as it is impossible, 

 without the most careful breeding, to be certain to what 

 extent many of the species are liable to variation ; were 

 I to accept, on the one hand, the views of the collector, 

 the amount of variation represented by some species 

 would be so extraordinary as even to invalidate generic 

 characters ; form of wing, pattern, and coloration would 

 in short entirely fail to define a species. On the other 

 hand, were I to follow the plan adopted by.M. Guenee 

 in his " PhaUnites," of considering as specific nearly 

 every difference of coloration, I should undoubtedly go 

 too far; this error, however, would in my opinion be 

 preferable to the former. I therefore propose to follow 

 a middle course, and regard as distinct all forms ex- 

 hibiting differences in such characters as have hitherto 

 been considered generic ; and all in which the position 

 of markings or the entire style of coloration is dis- 

 similar. 



The series before me is a remarkably fine one, and is 

 an evidence of the indefatigable energy and zeal with 

 which Mr. Edmonds has worked : so fine a series must 

 of necessity include the greater part, if not all, of the 

 species known to M. Blanchard, when preparing his 

 descriptions for Gay's ' Fauna Chilena ' ; unhappily, 

 however, these descriptions are so vague, I might almost 

 say careless, and the illustrations in the Atlas are so 

 exceedingly inaccurate, that it is impossible in many 

 instances to decide whether or not one possesses the 

 species intended. 



TRANS. ENT. SOC. 1882. PART III. (SEPT.) 2 Y 



