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VII. Intersexual forms o/"Plebems argus L. (aegon. Schiff.), 

 By E. A. Cockayne, D.M., F.R.C.F. 



[Read March 1st, 1922.] 



Plates V-IX. 



In 1916 I published a paper in the Transactions of this 

 Society on Agriades coridon Poda, ab. roijstonensis Pickett. 

 This year through the kindness of a fellow-entomok)gist 

 I was enabled to visit a colony of P. argus in one of the 

 home counties, where a corresponding gynandromorphous 

 or intersexual form occurs. 



Geographical Range. 



Long series of intersexes of a.gus of this kind 

 existed in the Briggs and Sidney Webb collections from 

 Dover, where it was taken as early as 1864 and as late 

 as 1889. A specimen was recorded from the New Forest 

 (Proc. Ent. Soc. Lond., 1872, p. xhii), and another was 

 taken in the same district by Clark (Entomologist, 1897, 

 XXX, p. 179). 



W. Castle-Russell took a considerable number in Surrey 

 in one small locality (Ent. Record, 1917, xxix, p. 211). 

 None could be found amongst the argus from neighbouring 

 heaths, but I have seen one taken in 1921 in another part 

 of the county. 



Max Wiskott figures one from Obefbayern, in which 

 the wings on the left side with male characters measure 

 10 mm., and those on the right, which are entirely female, 

 measure 12 mm. (Lepidopteren-Zwitter meiner Sammlung, 

 1897, Taf. iii, no. 16). Alexander Heyne gives a full 

 description of another taken at Wildenhain near Torgau. 

 The left side, heavily sprinkled with blue and with a 

 black border and whitish fringe, measured 10-5 mm., 

 whereas the right side was brovv^n with a brown fringe, 

 and measured 13 mm. There were orange lunules on both 

 hind-wings and the abdomen was female externally. The 

 left antenna was a Little shorter than the right (Rev. Ent. 

 Soc. Namuroise, 1901, pp. 23-24). 



Gillmer figures one splashed with blue on all four wings 

 taken by Krodel at Wiirzburg, May 1901. He says that 



TRANS. ENT. SOC. LOND. 1922. — PARTS I, II. (jULY) Q 



