

JOURNAL OF VARIATION. 



No. 6. Vol. II. August 15th, 1891. 



THE GENUS ACRONYCTA AND ITS ALLIES. 



By Dr. T. a. chapman. 



(Continued from page 77.) 



^RONYCTA {Ctispidia) alni. — Alni seems to come 

 nearer to psi, tridens, and strigosa than the remaining 

 species we have still to examine, though it is dis- 

 tinguished from all the rest of the genus by the 

 curious neck which marks off the anal armature of the pupa ; 

 this seems correlated with its manner of pupating, which is 

 very like that of leponna. In abti the elaboration for providing 

 abundant entanglement in the silk, of the end of the cocoon, 

 is found in this curious groove, the spines remaining of the 

 same simple type as in tridens ; whilst in leporina it is achieved 

 by an abundant multiplication of the spines and their curving 

 into very efficient hooks. 



The egg is laid at the end of June or beginning of July, 

 always solitarily, I conjecture on the upper side of the leaf, 

 though in captivity it lays them on either side. I recently had 

 an opportunity of observing psi deposit her eggs when in 

 freedom. The moth came from some little distance, laid two 

 eggs a quarter of an inch apart on the under side of a haw- 

 thorn leaf, and then flew off out of sight. I have already 

 recorded finding an egg of psi on the upper side of an oak leaf. 

 Psi as a young larva affects either side of the leaf, but as alui 

 lives on the 7ipper side, the eggs are probably laid there. 



When first laid the egg (PI. VIII., fig. 6) is nearly as colour- 

 less as that of psi, but soon assumes some coloration, and in 

 about three days, reaches its proper tint. For twenty-four 

 hours before hatching it becomes much darker, with the black 

 head of the larva occupying the summit. 



In form the egg is of typical Acronycta shape ; the diameter 



