224 PTILOTA. 



skin splits iloxvii the back, and the gnat, making use of its 

 pupa case as a boat, gradually draws itself out of its case, 

 upon which it sits until its wings are expanded. In pupae 

 which are inclosed in cocoons or other cases, different modes 

 of escape are required. How, for instance, can a moth, whose 

 beautiful wings and crested thorax indicate no previous strug- 

 gle, make its way through the cocoon, often as solid as the 

 hardest wood. This is effected either by the peculiar con- 

 struction of the cocoon, or by the operation of some fluid 

 emitted by the insect on its arrival at the perfect state. In 

 like manner the pupa; of flies and other coarctate diptcra 

 force off a scale, at one end of the dried skin, by inflating the 

 middle of the head into a large membranous vesicle ; and the 

 pupse of the caddice-flies, which are inclosed in the case in 

 which they resided whilst larvae, make their way through 

 the net-work covering which they had spun to defend its en- 

 trance. But the most curious circumstance connected with 

 this subject, is the mode of extrication of the males of the 

 gall insects ( Coccus), the pupa3 of which are strictly coarctate, 

 the imago making its escape backwards from beneath the 

 flattened skin of the larva, its wings being turned backwards 

 over the head. 



The developement of insects is very rarely attended with 

 those deviations from the ordinary rule, which are sometimes 

 met with in other tribes of animals. It has, however, been 

 recorded in the Entomological Magazine, No. 1 2, that a male 

 and female emperor moth (Saturnia pavonia minor) were pro- 

 duced from a single larva of an extraordinary size. Kirby 

 and Spence also mention that, according to Kleesius, a Ger- 

 man entomologist, two specimens of Gastropacha quercifolia 

 (the pine lappet-moth), were produced from one pupa, which 

 was large, being full two inches long, and one thick. These 

 circumstances are sufficiently marvellous, but the most mar- 

 vellous fact of all is that affirmed by Mr. Dale, in the Maga- 

 zine of Natural History, Nos. 19 and o4, viz., that he "once 



