90 THE ENTOMOLOGIST. 



at the base of each wing; the precise use of these winglets 

 has occasioned some speculation, but this matter also I must 

 leave in doubt. The penulliuiate or pupa state of Diplera is 

 verv different in different families; in some it somewhat 

 resembles that of certain Lepidoptera ; in others it is an 

 oblong object, quite smooth, and looking as though it had 

 been turned in a lathe. 



2. By passing through a necromorphous state, — Necro- 

 morplia, — in which the penultimate slate is provided with 

 mouth and organs of locomotion, detached from the trunk 

 throughout their length, but so swathed and enveloped in 

 separate cases that it can employ neither. The resemblance, 

 therefore, to the perfect insect is considerable, except in the 

 want of locomotive power. This group contains two 

 subordinate groups, principally by the character of the fore 

 wings: — (c) Hi/mpnoptera,'\xi which the imago has usually 

 four fully developed wings, which are membranous, naked, 

 and without hairs or scales, (d) Coleoptera, in which 

 the imago has two fully developed wings — the hind wings, 

 and two wing-cases which cover the wings, and appear to 

 take the place of fore wings: they are invariably called 

 elytra. These are not needed in ffying; they are gently 

 raised, some a very little, others to an angle of 45°, and 

 others even more still ; but in all cases, when raised at all, 

 they are sufficiently so to allow full play lor the hind and 

 only pair oi membranous wings. Besides this power of just 

 lifting the elytra, the insect seems entirely unable to move 

 them, and the wings are never seen vibrating as in other 

 insects; indeed they appear to want the systems of muscles 

 necessary for vibration. This want, which is perhaps a 

 most distinctive character of beetles, seems to have been 

 overlooked by entomologists generally, although noticed by the 

 late Mr. Dale in Stylops, which is a manifest Coleopieron. 



3. By passing through an isomorphous state, — IsomorpJia, 

 — in which all the stales are active and voracious, and of 

 similar form to the imago, except in wing. The imago has 

 four wings, all of them more or less coriaceous or leathery, 

 and all more or less available for flight ; the fore wings are not 

 merely raised to allow free action of the hind wings, but 

 even these share in the function of flight: this function is, 

 however, scarcely ])erfbruied wilh any energy, but is a sort of 

 half-hearted performance, notwithstanding the wonderful 

 migrations some of tliese insects perform. There are two 

 subdivisions: — (e) Urthoplera, having powerful mandibles. 



