The Bionomics of South African Insects. 473 



considerable rarity ; I know of only fourteen or fifteen 

 specimens, all of which, except two or three, were captured 

 by myself." 



0. The Origin and Meaning of the Three Chief Forms 

 of Limnas ehrysipims. 



I have often discussed the question set forth in the title 

 of this sub-section with my friend Colonel J. W. Yerbury, 

 who has observed this insect carefully in many of its local- 

 ities, and is deeply interested in it.* He believes that the 

 appearance of the various forms is controlled by environ- 

 mental influences — dryness or moisture — acting upon the 

 pupa at some critical period of special sensitiveness. The 

 facts recorded below do not seem to be consistent with 

 this interpretation. 



My friends Mr. and Mrs. S. L. Hinde, who have kindly 

 collected many specimens throwing light on problems to 

 which I have given much thought (see also pp. 44G, 447), 

 sent me two series of forms of Limnas ehrysip-pus, which 

 are of special value in relation to this discussion. 



The first set (of 15) was captured, almost on the sea- 

 level, in the uniform damp heat of" Mombasa, on May 6, 

 1900, and consists of four of the type-form of Limnas 

 clirysippus (1 $ and 8 ^), and eleven of the form Iduyii (9 

 $ and 2 $). All were taken in less than an hour on a 

 spot of ground a few yards in extent. They thus afford a 

 fair criterion of the proportionate numbers of the two 

 forms. 



The second set (of 13) was taken, at a height of about 

 5400 ft., at Machakos Road, on the Uganda Kailway, on 

 May 22, 1900, and consists of four of the type-form (3 ^ 

 and 1 ^), one aleip)poidcs {$), seven Idugii (2 $ and 5 '^), 

 and one dorippus {$). These also were taken on a spot 

 of ground a few yards in extent, in less than an hour. 



Mr. Hinde has given me information as to the climate 

 of the period in which the latter capture was made. It 

 is printed on pp. 447, 448, but it is well to re-state here 

 that May 22, 1900, was at "^ the end of a very dry wet- 

 season in an exceptionally dry year." The specimens show 

 the effect of these conditions, for they are on the average 



* J. W. Yerbury, Journ. Bomb. Soc. Nat. Hist., 1892, p. 207. 

 Col. Yerbury's observations on the species are also quoted by Dr. 

 A. G. Butler in. Proc. Zool. Soc. Lond., 1884, p. 478; 1885, p. 756. 



