148 ENTOMOLOGY. 



draws itself out of the rent. It stands on its feet for a few 

 minutes, while its wings expand, and then takes flight and 

 sails gracefully through the air on its broad wings. 



Figs. 175 and 176 illustrate the metamorphosis of Danais 

 arcJiippus from the egg to the butterfly; but Fig. 175, c, 

 is incorrect so far as it shows how the partly formed 

 chrysalis is suspended. According to Riley's latest observa- 

 tions and figures, after the caterpillar has spun the little 

 button-like mass of silk, as at a, it entangles in the silk the 

 hooks both of its last pair of legs, and those of the "supra- 

 anal plate," situated above the legs, and which becomes the 

 stout spine at the end of the chrysalis, called the "cre- 

 master." The caterpillar then works its skin back to the 

 end of the body, as at I. The anal legs of the larva are 

 represented in the chrysalis by two sustaining knobs which 

 catch in the retaining membrane, and with the aid of a 

 rectal ligament suspend the pupa, and prevent it from 

 falling at the critical point when the cremaster is withdrawn 

 from the larval skin. Finally, while temporarily supported 

 by the two elastic suspensory membranes, tlie chrysalis so 

 twists and turns itself that the booklets of the cremaster 

 become securely fastened in the silk button, and the old 

 larval skin is discarded, the chrysalis appearing as at D. 



In most Lepidoptera the males emerge and fly about for 

 some time before the females. Darwin infers that the 

 adult males of most Lepidoptera generally exceed the fe- 

 males in number, " whatever the proportion may be at their 

 first emergence from the egg" (Descent of Man, i. 305). 



The " assembling" of moths is a curious fact. If a vir- 

 gin silk-worm moth be exposed in a cage, great numbers of 

 males will collect about the box. It is so with some beetles, 

 as Prionus brericornis and probably other longicorns. 



The wings of the two sexes of Lepidoptera often differ 

 in venation, and usually in outline; while the males of 

 certain South American butterflies have tufts of hair on 

 the edges of the wings, and horny excrescences on the 

 disks of the hinder pair. The males of certain butterflies 



