#^ 





JOURNAL OF VARIATION. 



No. 4. Vol. III. April ISra, 1892. 



THE GENUS ACRONYCTA AND ITS ALLIES. 



By Dk. T. a. chapman. 



( Co n tin lied jro in page 29.) 



\CRONYCTA {Ciispidia) aceris. — This species is 

 usually associated with Icporina, on account of both 

 having hairy larvae, but the egg colouring, the 

 different distribution of pale segments in the newly 

 hatched larva, and the method of pupating, make it most 

 probable that this aspect of the full-grown larva is a resem- 

 blance, not due to a close relationship, but is a case of similar 

 structure independently developed in allied species. The 

 arrangement of the hairs also differs very markedly in the 

 two species. In both, the hairs of the general surface are 

 well developed, but in aceris, the tufted distribution is largelv 

 due to a special development of the hairs of the tubercles, 

 only slightly paralleled in Icporina and not occurring in any 

 other British species. 



The egg (PI. VIII., fig. 4) is large, i.i mm. in diameter, 

 rather flat, ribs numerous — usually 70 to 75 — but sometimes as 

 few as 50. When first laid it looks very like that of psi or 

 tridens, but is a little more opaque. As the inner egg shrinks 

 and leaves a colourless margin, it assumes a rich chocolate 

 colour with pale straw-coloured spots, which are rather large 

 and somewhat irregular in distribution and shape, being fre- 

 quently almost angular rather than circular, and often run 

 together into streaks and blotches, but suggesting a never- 

 attained type of a central spot, and three rings surrounding 

 it, of which the inner is imperfect and encroaches on the 

 central spot and the outer is marginal, the intermediate one 



