82 INTRODUCTION. 



puoae obtected. In this state, they are of course in* 

 capable of moving from the place to which they are 

 fixed, and indeed of making a movement of any kind, 

 save twisting the abdomen to one side, which they 

 generally do when disturbed. Scarcely any other 

 symptom of animation is perceptible, but during the 

 continuance of this apparent torpor some important 

 changes are taking place internally. The milky fluid 

 which at first filled nearly the whole of the interior, 

 is gradually absorbed and assimilated by the growing 

 embryo, while the watery portions pass off by eva- 

 poration. In this way the germ of the future fly is 

 enlarged and matured, till it ultimately fill the whole 

 cavity of the puparium or pupa-case. The process 

 of respiration is likewise carried on, though to all 

 appearance in a very languid manner, through thft 

 medium of a series of spiracles or air-holes placed 

 on the sides of the abdominal segments. 



The greater number of butterfly chrysalides are 

 of an angular figure, wide and obtuse at the head, 

 and tapering to the tail in the form of a cone. 

 Besides having various angular projections on diffe- 

 rent parts of the surface, the head terminates in a 

 conical projection, which is very frequently double. 

 In a pretty extensive group, however, (comprising 

 the genera Thecla, Lycsena, &c.) the chrysalides are 

 without any protuberance, and of a conical shape, 

 the anterior extremity being simply rounded. The 

 prevailing colour is brown, often inclining to bkck ; 

 but, in some instances, they are adorned with very 



