228 Dr. E. A. Cockayne on 



extent of blue scaling at the base, tliat on the hind-wing 

 extending almost to the lunules. The blue scales are 

 serrated and there are no androconia. It seems to me to 

 be a true heterochroic specimen like the one from the 

 New Forest described under the name ab. duplex Cockerell. 

 This had the wings on the right side brown, those on the 

 left strongly shaded with blue but not reduced in size. 

 According to Tutt it showed on each half a different form 

 of female colouring and was not a gynandromorph (Bond, 

 Ent. Month. Mag., 1872-73, ix, p. 200; Entomologist, 

 1889, xxii, p. G). 



Four or five females of coridon, showing a different 

 kind of female upperside colouring on the two sides, like 

 these two females of argus, have been taken at Royston. 

 It seems to me to be more than a coincidence that all have 

 come from localities where the intersexes are found. 



Frequency op Intersexes. 



Although the colony is compact and isolated, it is 

 difficult to estimate the percentage of intersexes. On 

 two evenings, when I examined females asleep, I took two 

 out of 230 and one out of 175. Allowing for the fact that 

 some intersexes had been captured previously, at least one 

 per cent, of the total number of females must be intersexes. 

 During the daytime I took them at about the same rate 

 as on these two evenings, and I think this estimate is 

 fairly correct. I am sure the percentage of intersexes of 

 argus in this colony is much higher than that of coridon 

 ab. roijstonensis at Royston or near Tring. 



Habits. 



The flight and general behaviour of the intersexes 

 resemble those of females. Twice I saw one being pursued 

 by a male, and it quivered its wings and took up the 

 attitude of a normal female. I am told that a number 

 have been found paired, and my dissections show that 

 this happens frequently. Three of my specimens laid a 

 few eggs and they were laid singly in the usual way. The 

 eggs were fertile and one larva has died after eating a 

 hole in the shell. 



External Characters. 



AH my 58 specimens have androconia mixed with the 

 blue scales even where these are few in number. The blue 



