264 



Mr. Horace A. Byatt on 



It is due to the suggestion of Professor Poulton that 

 this would be an excellent opportunity to ascertain what 

 numerical relation the Pseudacrsea bears to its model 

 chrysippns that this paper has been hastily prepared in 

 the Hope Department at Oxford before my return to 

 Central Africa. 



The country in which Kayambi is situated does not 

 differ greatly from the rest of the plateau to the W. 

 of Lake Nyassa and N.E. Rhodesia. Large stretches 

 of undulating plains, covered with thin scrubby bush 

 or dense tall grass, are intersected at intervals of 5-20 miles 

 by streams and rivers. In the latter months of the year, 

 when these insects were mostly collected, these plains 

 are bare, dry, and dusty, grass and bush being burnt up 

 by the annual bush-fires: and only along the streams is any 

 verdure found. Pere Guilleme describes the soil as fertile 

 along the course of the rivers, but elsewhere the district 

 is generally poor and sandy, and for this reason sparsely 

 inhabited, and he remarks on bush-fires being the cause 

 of the general scarcity of insect-life except along the 

 water-courses, where the vegetation is untouched by fires, 

 and where forest-giants, trailing creepers, and tree-ferns 

 flourish. 



The altitude of Kayambi is about 3950 ft. above sea- 

 level; and its position roughly 20' S. and 31° 50' E., 

 some two clays' march from File, and three from Abercoin, 

 on the Nyassa-Tanganyika plateau. 



The respective numbers and species in the collection 

 were worked out in the Hope Department and are stated 

 in tabular form below : — 



SPECIES. 



Limnas chrysippns 



do. do. var. dorippus 



Pseudacrxa poggei 

 Hypolimnas misippus . 



„ „ $ var. inaria 



Total number in group 441 



From this table it will be seen that Pseudacnva poggei 

 is by no means so rare as has been hitherto supposed ; 

 its proportion to L. chrysippus is no less than 472 per 

 cent. The doripjncs, KL, or Jclugii, But!., form of chrysippus 



