424 LECTUKE XVIII. ' 



The Orthopterous and Hemipterous insects, characterised in 

 entomology by a semi-complete metamorphosis, are, at one stage of 

 their development, apodal and acephalous larvae, like the maggot of 

 the fly ; but instead of quitting the egg in this stage, they are 

 quickly transformed into another, in which the head and rudimental 

 thoracic feet are developed, to the degree^ which characterises the 

 liexapod larvse of the Carabi and Petalocera ; the thorax is next 

 defined, and the parts or appendages of the head are formed, at 

 which stage of development the young Orthopteran corresponds with 

 the hexapod antenniferous larva of the 3Ieloe ; but it differs from 

 all Coleopterous larvae in being inactive and continuing in the Qgg 

 almost until all the proportions and characters of the mature insect 

 are acquired, save the wings. 



Oddly enough that development is called " a complete metamor- 

 phosis," which is permanently arrested at the stage in which the 

 orthopterous insect enters life, and the only hexapod insects, as the 

 apterous Cimex and Pediculus, in which the metamorphosis is never 

 completed, are those in which it is said to be " complete." Bur- 

 meister, however, seems to be the only entomologist who has pointed 

 out the inaccuracy of the Fabrician definitions ; but he failed to free 

 himself from the thraldom of words when he supposed that, in the 

 development of any insects, there was, "properly speaking, no change 

 of form, but merely a repeated casting off of the exterior skin." * 



With regard to the terms incomplete, obtected, and coarctate, they 

 indicate, in fact, comparatively unimportant modifications of the 

 last moulted skin of the larva of those insects which are torpid or 

 quiescent at the period of the development of the wings. In the bee 

 and beetle, and all Hymenoptera and Coleoptera, the legs, wings, and 

 antenna3 bud out and carry with them processes of the last larval 

 integument, which thus forms in the pupa special sheaths for each 

 growing organ of sense or locomotion in the perfect insect, and 

 which organs are therefore comparatively free, although the pupa 

 be quiescent. Lamark called such pupas " Mumiae." 



In the obtected Lepidoptera the growing wings, antlia, antennse, 

 and thoracic legs are only partially covered by the pupal integument, 

 being lodged in recesses on its inner surface, which make corre- 

 sponding projections on its exterior, where their form and position 

 may thus be recognised. 



In the coarctate metamorphosis of the Diptera, the larva sheds its 

 last skin before the growing legs and wings have impressed their 

 forms upon it, and the exuvium constitutes an egg-shaped horny case, 



* CCLXV. 



