88 THE ENTOMOLOGIST. 



after only twenty-three days of pupal development. The 

 temperatures were measured by thermometers sunk in the sand. 



The moths ran about after emergence for several minutes 

 before their wings began to expand, thus indicating as usual 

 that in the natural state the species was accustomed to encounter 

 and overcome some difficulties on first leaving the pupal shell, 

 which would be fatal if the wings expanded at once. 



One of the moths — the larger one — appeared to be normal 

 in facies ; when, however, I first saw the other— smaller 

 specimen — in an uncertain light, I thought that the "skull" 

 markings on the thorax were absent. Looking closely, however, 

 it became evident that the usual markings were there, but that 

 they were so dark in colour— of a dusky brownish tint instead of 

 bright yellowish white — as to have become comparatively incon- 

 spicuous ; otherwise the specimen did not appear to differ from 

 the type. 



I observed these interesting moths for some time alive, and 

 the larger one, with the normal and very conspicuous " Death's- 

 head " on the thorax, gave me a surprise. Soon after the 

 freshly emerged insects had dried their wings and settled 

 themselves into the position common to most moths when at 

 rest, I approached the cage, which stood in an obscure corner, 

 with the intention of studying the appearance of the specimens. 

 The larger one was resting against the side of the cage, a dusky 

 inconspicuous shape ; the smaller moth was hanging on to the 

 roof with its head towards me, and its very large eyes glowed 

 like live coals in the half-light. 



Looking closer at the grey uncertain form on the side wall 

 of the cage, I was struck with its likeness to the hooded, long- 

 robed figure of a medieval monk, but with a naked, bleached 

 skull grinning out from the hood. With my head inside the 

 breeding-cage, I inadvertently disturbed the moth on the roof, 

 whereupon it uttered a series of sobbing squeaks, and then it 

 suddenly seemed to me as if the white "skull "-cap in the 

 dark form on the side of the cage just before my face had 

 become alive, and ivas nodding out at vie. The impression 

 in the gloom was so weird and startling that I turned my head 

 towards the light to see if my eyes were at fault, but nothing 

 evidently was the matter with them. Looking back at the 

 moth, I again saw the " skull " nodding horribly, and both 

 moths were now emitting the plaintive squeaks for which they 

 are well known. 



Nothing remained but to fetch the lamp, and to bring its 

 light to bear on these twentieth-century spectres. Immediately, 

 then, it became plain that the white " skull "-like disc on the 

 thorax was movable, and now palpitating up and down rapidly,* 



* Evidently pumping the air necessary to cause the squeaking sounds 

 into the proboscis. 



