Seasonal DimorpJiism in Butter Jlies. 205 



On the whole Mr. Marshall's view as to the incipient 

 mimicry of Acr/ea serena, Fabr., by B. gotzius seems a 

 very probable one. The underside of tlie wet-season 

 B. illthi/ia perhaps recalls slightly that of the Indian Acrma 

 (Tclchinia) viohv, Fabr., but tlie likeness in tliis case is of 

 a remote kind. 



" Ilalvcrn, Natal; May 14, 1897. — Experiments on 

 snhmitting 'pivpaa to conditions of moisture or dry heat. 

 The apparatus used for dry-forcing was a covered tin (into 

 which was poured a little water) placed on a tripod over a 

 spirit-lamp. On the lid of the tin was placed some dried 

 sand, into which was stuck a stick bearing the pup*, which 

 were covered with an inverted glass. The ' damp tin ' 

 contained very damp sand, the pupse being separated 

 from it by a grating of perforated zinc ; and the mouth 

 of the tin was covered with a cloth, on which was placed a 

 Avet sponge. 



" Experiment with Acnea cahira. 



1897 

 March 20. Two larvce {a and h) pupated this morning ; 

 I put them in the dry forcer in the evening. 

 ,, 28. A larvae (c) pupated, and was left in the 



breeding-cage. 

 „ 81. Two larvse {d and e) pupated ; d put in the 

 forcer, c left in breeding-cage. 

 April 6. c emerged, being a normal male. 



,, 8. e emerged, a normal female; d not yet 

 emerged, but still alive; a and h probably 

 dead. 

 „ 9. d evidently too weak to emerge, so I helped 

 it out, but it was only just alive, and 

 wings did not expand. Its colouring was 

 apparently normal. a and h never 

 emerged at all, but shrivelled up. 

 " Besult. — Acrmi cahira apparently unable to exist in a 

 very dry, hot climate, as might be supposed from its dis- 

 tribution. It is noteworthy that two pupse of Tcrias brigitta 

 emerged satisfactorily in forcer during the same period. 



" Experiment with Pinacopteryx pigea. 



1897 

 April 2. Seven larvse (« to g) pupated. 



