( xvii ) 



was a well-mai'ked alternation of seasons, and not always 

 even then. These facts suggested questions which could only 

 be answered after the collection of further data. Meanwhile, 

 Mr. Gr. A. K. Mai^shall had done much to extend our know- 

 ledge of the subject by his recent observations and experi- 

 ments carried on in South Africa. Besides the case of the 

 production of Teracolus auxo from eggs laid by T. topha, 

 which had been already announced by Mr. Trimen, he had by 

 actual breeding experiments raised the question of the identity 

 of other pairs of named forms from the region of conjecture 

 to that of positive proof. This statement was illustrated by 

 the exhibition of one of the specimens of T. auxo above 

 referred to ; and of parent individuals of Teracolus achine, 

 T. oinpliale, Terias senegalensis, Byhlia vulgaris, and B. ilithyia, 

 accompanied in each case by their offspring, which belonged 

 respectively to the forms Teracolus ayitevippe, T. theogotw, 

 Terias sethiopica, Byhlia gotzius, and B. simplex (African 

 form). Mr. Marshall had also succeeded in proving the 

 sensitiveness of certain forms in the pupal state to artificial 

 conditions of humidity and temperature. Heat unaccom- 

 panied by moisture had caused in Byhlia ilithyia, Pinacopteryx 

 2ngea, and to a less extent in Crenis hoisduvalii, an approach 

 to the " dry-season " coloration ; while in the presence of 

 moisture in addition to heat, the " winter brood " of Teracolus 

 achine, T. omphale, and T. phlegyas showed a tendency to 

 revert to the garb of the rains. Moisture without heat 

 produced a slight determination towards the rainy season 

 form in Crenis hoisduvalii, and a more decided one in Pina- 

 copteryx pigea. These effects, though unmistakable, were far 

 less striking than those obtained with European species by 

 artificial conditions of temperature in the hands of Merrifield 

 and Standfuss. 



In the discussion which followed Colonel Yerbury said that 

 a temporary rainfall in a dry season in dry places had a 

 marvellous effect in producing intermediate and wet-season 

 forms. 



Mr. F. Merrifield said he thought it highly credit- 

 able to Mr. Marshall that, situated where he was, he had 

 been able to obtain such valuable scientific results. It was 



PROC. ENT. SOC. LOND., II. 1902. B 



