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Show 28 MR. GUY A. K. MARSHALL ON THE [Jan. 19, doubtless seem to many at first sight to be unwarranted, but after a careful study of a large number of insects, including many type-specimens, I can arrive at no other conclusion. Speaking roughly, the position is as follows : - O n the eastern side of the Continent we have T. omphale, with its heavy black bars in both wings, during the wet season, which is replaced during the winter by its dry-season form T. theogone, in which the black bars disappear more or less completely ; the black borders are much reduced, and the underside of secondaries becomes speckled with grey hatching, with a darker transverse bar on disc. But, as so often happens in such cases of seasonal dimorphism, at the change of seasons specimens are met with uniting the characteristics of both wet- and dry-season forms. Some such examples were caught by the late Mr. E. C. Buxton in Natal and Swaziland, which resemble T. theogone in their shape and in the absence of the black bars, but have the border of the apical patch as in T. omphale, and the underside is white, without trace of grey hatching. These were referred, and I think justifiably, to T. evippe by Mr. Trimen (=pseudocale, Butl.), who at that time regarded T. omphale and theogone as distinct species. In Eastern Africa, therefore, we have T. evippe as an intermediate seasonal form of T. theogone-omphale, aud this is probably also the case in Angola, on the West Coast; but when we reach Guinea and Sierra Leone T. evippe is the predominating form, and the extremes are apparently very scarce, or even absent, this being perhaps due to a greater uniformity of general conditions, which might tend to produce a mean or intermediate form. The question then arises whether T. evlppeis specifically distinct from T. omphale. Personally I think not, but I regard it as a local development or variation of that species, which still exhibits a series of gradations linking it to the parent form. Then by the law of priority evippe must stand as the name of the species, and T. omphale be ranked as a local variety. T. omphale, as defined by Trimen (S. Afr. But.), ranges practically throughout Africa, south of the Equator ; to the north of this it is only recorded from Senegambia (Hope Coll., Oxford) and Abyssinia, and appears to be very scarce all along the West Coast. T. hybrldus is another example of intermediate seasonal coloration, resembling the summer T. omphale above and the winter T. theogone below ; the type is from Plettenberg Bay, Cape Colony. T. complexivus (Delagoa Bay and Somaliland), omphaloides (Natal, Zululand, Swaziland, Transvaal, and Kilimanjaro), and corda (Swaziland) are also intermediate, but nearer the dry-season form than T. hybrldus, as they have the upperside black markings more reduced, the black bar in hind wings being usually obsolescent and often absent. In the latter case they constitute the Anthocharis theogone var. B of Boisduval. T.eplgone,frow Zomba, the White Nile, and Arabians inseparable from T. theogone. The single female in the British Museum from Arabia is of interest, having lost all the discal black markings (probably as a result of the arid climate), and thus represents an extreme example of local dry-season coloration. |