1897.] ON THE BUTTERFLIES OF THE GENtTS TERACOLUS. 3 



The following papers were read : — 



1. On the Synonymy of the Butterflies of the Genus 

 Teracolus. By Guy A. K. Marshall, F.Z.S., of 

 Salisbury, Mashonaland. 



[Eeceived July 2, 1896.] 



In view of the rapidly increasing recognition of the fact that 

 many families of Butterflies exhibit very strougly-marked differ- 

 ences in their wet- and dry-season broods, it seems advisable that 

 some attempt should be made to revise the nomenclature of these 

 insects in the light of our wider knowledge. The phenomena of 

 seasonal dimorphism are so varied and so inconstant that it is 

 practically impossible at present to lay down any general rules 

 for the determination of seasonal forms in Ehopalocera without 

 making them so general as to be almost useless. Indeed, so 

 susceptible are these insects to the influence of their environment, 

 that some of the more widely ranging species exhibit different 

 seasonal modifications in different localities. 



This great complexity renders it extremely difficult for purely 

 museum workers to accurately determine which characters are 

 really specific and which are seasonal. For not only is it necessary 

 to know the locality from which a given specimen may have come, 

 but also some knowledge of the altitude and general conditions of 

 the neighbourhood is requisite, and the climate is of even greater 

 importance. The date of capture is again a detail of the highest 

 significance when accompanied by a knowledge of the environment 

 in which a species lives, but without this it is almost useless as a 

 basis for argument, and is only apt to create confusion : moreover, 

 an unusually wet or dry season may retard or accelei-ate the 

 appearance of the various seasonal forms, so that without knowing 

 the exact meteorological conditions of any given year the date of 

 capture cannot be absolutely relied on, apart from the fact that the 

 forms in many eases have a tendency to overlap. In this latter 

 case the condition of the specimen when it is captured is often 

 significant. 



It will be therefore seen that the determination of species in 

 genera which are known to be dimorphic must be based to some 

 extent on the notes and observations of field-lepidopterists ; and it 

 is only for this reason that I have ventured to attempt a short 

 revision of the nomenclature in so complicated a genus as Teracolus. 

 I had at first intended deahng only with the African species occur- 

 ring south of the Zambesi, almost all of which I have been able to 

 observe in their natural haunts, but owing to the wide range of 

 many of these Butterflies, and the close relationship and even actual 

 identity of some of the African and Indian species, I have found 

 it advisable to deal with the whole genus. 



Apart from my field-observations during five years' residence in 

 South Africa, I have had opportunities of investigating a very large 



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