Seasonal DimorpJdsm in Bidterjiics. 213 



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

 " T. pallcne " from Mashonaland as specitically different 

 from T. om^yliale. 



It will be seen from the above descriptions that the 

 damp heat to wliich many of the specimens of T. omphaJc 

 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 phJcyyas, Butl.* {T. dijficilis, 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 hindwinffs 

 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 Teracolus men- 

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

 tracts bear reference to the African forms of the senus 

 Bi/blia, Htlbn. 



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

 ilithyia and aclieloia, 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 Byhlia, as I have now five pupae and three 

 larvae bred from authenticated eggs of ilithyia, and one 

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

 season form of B. acheloia ( = B. gotzitbs). 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 ray 

 damp experiments, together with those already sent, might 



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

 inserted here for convenience 



