168 Dr. E. A. Cockayne on the scales of Agriades thetis. 



through the blue Lycaenids, may well be Mendelian 

 recessives to the normal blue males. The " dolus " and 

 " menalcas " group may be examples of Mendelian reces- 

 sives superseding the normal dominants through whole 

 species, as the recessive form of Callimorjpha doiinnula with 

 yellow hind-wings has entirely replaced the dominant with 

 red hind-wings in certain parts of Italy. This suggestion 

 is one put forward in order that some one may take the 

 necessary steps to prove or disprove it. 



•A further point of interest in connection with the leaden 

 thetis is that Mr. L. W. Newman thinks that they are 

 unusually fragile. It is quite possible that the whole 

 wing membrane is thinner than that of normal males, 

 and, if so, it may be correlated with the thinness of the 

 " colour scales." I have not been able to satisfy myself 

 on the point, as I did not wish to destroy a specimen for 

 this purpose. 



Explanation of Plate XI. 



1. " Colour " scales of leaden male Agriades thetis. 



2. Blue " colour " scale of normal male Agriades thetis. 



3. Smoky (light absorbing) scale of leaden male Agriades thetis. 



4. Androconial scale of leaden male Agriades thetis. 



The fine regular striae of the blue scale are only roughly indicated. 

 The drawings are magnified equally. 



