Ixxvi 



armature was found in Uganda, especially towards its eastern 

 border, although the pattern was always that of the less 

 heavily marked western dardanus. At Nairobi, near the 

 Kikuyu Escarpment but at a lower level (about 5500 ft.), the 

 males were larger and their patterns transitional between 

 polytrophus and tibullus, comparatively few retaining the 

 reduced hind-wing band of the Western form. 



Dr. Jordan considered that the structural differences in 

 the male armature were not such as to prevent interbreeding, 

 and it was probable that the whole community from the 

 West to the East Coast was syngamic. In these circumstances 

 a fluctuation in the line of demarcation between adjacent 

 areas with different patterns was by no means improbable 

 and afforded the most likely interpretation of the appearance 

 of males, only differing from those of polytrophus by their 

 greater size, at Kibwezi, over a third of the distance between 

 Nairobi and the East Coast. It would be of the highest 

 interest to continue the observations in future seasons and 

 also to determine whether the same change has occurred in 

 localities between Kibwezi and Nairobi and also in those still 

 nearer to the East Coast. 



Delayed development a result of the in-breeding op 

 Abraxas grossulariata. — Prof. Poulton said that since 

 the summer of 1917 he had, with the kind help of Miss Balfour, 

 been breeding families which had all sprung from the eggs 

 laid by a female taken in the garden of St. Helens Cottage, 

 St. Helens, Isle of Wight. No fresh blood had been introduced 

 at any time, but apart from this no attempt was made to 

 keep the different strains separate. One of the earliest effects 

 observed was the delaying of development which had reached 

 its climax in a larva of the fifth generation exhibited to the 

 meeting. This caterpillar, the only survivor of its family 

 (although one other family produced several imagines during 

 the past summer), and now about half grown, had been 

 sleeved out upon Prunus pissardii on July 21, 1921 ! It was 

 apparently healthy, and had been observed freely feeding on 

 the morning of that day (October 18). 



The results were so extraordinary that it might be 

 supposed that a larva hatched in 1922 had been accidentally 



