Seasonal Dimorphism in Butterjlies. 213 



clear that there is no reason for considering Mr. Marshall's 

 " T. palhne " from IVIashonaland as specifically different 

 from T. omphale. 



It will be seen from the above descriptions that the 

 damp heat to which many of the specimens of T. omphale 

 were exposed was not entirely without effect ; though the 

 changes in the direction of the wet-season form are no 

 doubt less marked than those produced in the case of T. 

 achine, where the heat employed was greater. 



3. Teracolus phlegyas, Butl,* {T. difflcilis, E. M. Sharpe). 



One specimen : Salisbury, Mashonaland. Larva sus- 

 pended June 6, 1898 ; placed in damp forcer June 7 ; 

 pupated same day; removed June 30 ; emerged June 31. 

 An intermediate female, on the whole nearer to the dry 

 than to the wet-season form. The dark markings on the 

 upper surface of the forewings, including the discoidal 

 spot, are, however, somewhat strongly developed for a dry- 

 season form ; and there is a well-defined grey basal patch, 

 but no dark inner-marginal bar. Beneath, the hindwings 

 have lost the definite spots of the wet-season phase, but 

 have not assumed the dry-season colouring in its full 

 development. 



This completes the list of specimens of Tcracolus men- 

 tioned by Mr. Marshall in his letters. The succeeding ex- 

 tracts bear reference to the African forms of the ffenus 

 Bijhlia, Hllbn. 



" April 25, 1899. — I have a few authentic eggs of Byhlia 

 ilithyia and achcloia, which may perhaps decide the justice 

 of Dixey's contention as to the specific validity of the 

 latter. 



" April 19, 1901. — I hope to be able to get some definite 

 evidence as to Bi/hlia, as I have now five pup<B and three 

 larva3 bred from authenticated eggs of ilithyia, and one 

 pupa and six larvae from those of vulgaris, i. e. the wet- 

 season form of B. acheloia ( = B. gotzius). The resulting 

 butterflies will also prove the seasonal variation in the 

 two forms. So far as my present material goes, I find 

 that there is a very slight colour-distinction between the 

 two larvae in the last stage only. 



" Sept. 27, 1901. — The specimens resulting from my 

 damp experiments, together with those already sent, might 



* This, though belonging to an earlier series of experiments, is 

 inserted here for convenience 



