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Show 1897.] ON THE BUTTERELIES OF THE GENUS TERACOLUS. 3 The following papers were read :- 1. On the Synonymy of the Butterflies of the Genus Teracolus. By G U Y A. K. M A R S H A L L , F.Z.S., of Salisbury, Mashonaland. [Received July 2, 1896.] In view of the rapidly increasing recognition of the fact many families of Butterflies exhibit very strongly-marked differences 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 Bhopalocera 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 accelerate the appearance of tbe 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 cases 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 aud 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 dealing only with the African species occurring 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 tbe 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 1* |