E. A. COCKAYNK 87 



He refers to throe other larvae which showed a mosaic of whiti; and 

 dai'k colour, and says the condition is excessively rare but is well known 

 to silk-worni breeders. 



Toyania has proved that the zebra is a simple dominant to the 

 unicolorous white. 



Itisects showing segregation of somatic characters {Heterochroism) but 

 no segregation of sexual characters (Gy nandromorphisni). 



(1) Acidalia virgidaria. 



Right side ab. bischoffaria, left side type. Bred by A. Bacot, with 

 specimens wholly melanic (ab. bischoffaria) and wholly typical. Ex- 

 ternal characters and external genitalia were of one sex only. The 

 secondary sexual characters in this species, especially in the antennae 

 and legs, show marked dimorphism. 



(2) Abraxas sylvata. 



Tutt in the Entomologists' Record, 1897, ix, p. 306, describes the 

 aipture of several heterochroic examples of this species. 



(a) One with left forewing dull smoky grey (ab. suff'usa Tutt), the 

 other three wings being normal. 



{b) Others showing various mosaic arrangements of type colour 

 and that of ab. suffusa. 



(c) One with right forewing suffused with smoky cream colour 

 (ab. obscura Tutt), the other three wings being typical. 



(d) One with left forewing ab. obscura, the other three wings being 

 typical. 



The ab. obscura has both forewings of smoky cream colour and both 

 hindwings of the normal white, so that these last two examples may be 

 regarded as half ab. obscura and half type. 



The ab. suffusa, on the contrary, has all four wings of a leaden grey. 



These specimens were all taken in the same wood at the same time, 

 in a year when the ab. obscura and ab. suffusa were both most unusually 

 common. 



(3) Abraxas grossulariata. 



At the Lancashire and Cheshire Entomological Society in November 

 1914, Mr R. Tait, Junr., exhibited a specimen with the wings on the 

 left side black, with the exception of a few white marginal streaks, 



