206 INSECTA, 
two of which serve as a sheath to the third, in those which are provided 
with an ovipositor; and one alone, the superior, has a groove under- 
neath for lodging the two others. In those where this ovipositor is 
transformed into a sting, this offensive weapon and the oviduct are 
serrated at the extremity. 
M. Jurine has discovered good auxiliary characters for the distinc- 
tion of genera, in the articulation of the wings *; to describe them, 
however, would not be in unison with the nature of this work, and 
could not remove the necessity of referring to his. We will merely 
observe that he chiefly employs those resulting from the presence or 
absence, number, form, and connexion of two sorts of cells situated 
near the external margin of the superior wings, which he styles ra- 
dial and cubital. The middle of this margin most commonly presents 
a little callosity called the wrist or carpus. From the latter arises a 
nervure, which running towards the extremity of the wings, forms, 
in conjunction with this margin, the cell named radial, that is some- 
times divided into two. Near this spot arises a second nervure, 
which also proceeds to the posterior margin, leaving a space between 
it and the preceding one—this space is that of the cubital cells, the 
number of which varies from one to four +. 
The Hymenoptera undergo a complete metamorphosis. Most of 
their larvee resemble worms, and are destitute of feet; such, for in- 
stance, are those of our second and following families. Those of the 
first have six hooked feet, and frequently from twelve to sixteen 
others that are simply membranous. These latter have been named 
pseudo-caterpillars. Both kinds have a squamous head provided 
with mandibles, maxillz, and a lip; at the extremity of the latter isa 
fusus for the transmission of the silky material that is to be employed 
in constructing the cocoon of the nymph. 
Some feed on vegetable substances, while others, always destitute 
of feet, devour the carcases of Insects together with their larve, 
nymphs, and even eggs. 
To remedy their want of locomotive powers, the mother furnishes 
them with provisions, sometimes by transporting aliment into the 
positor or sting. When they form a sting, the superior receives the other in an in- 
ferior canal or groove. In the Tenthredinetz, the ovipositor consists of two pieces, 
resembling blades of knives, applied one against the other by the side; they are 
striated transversely, and dentated along the margin. 
* Nouv. Méth. de class. les Hymen. et les Dipt. 
+ See Encyc. Méthod., article Radiale, where this method is well described and 
perfected. Jurine has also published an excellent work on the organization of the 
wings in the Hymenoptera, in the Mem. Ac. Sc. Tur. We are also indebted to M. 
Chabrier, for his researches on this matter; they are, however, more general in their 
application. They are inscrted in the Mém. du Mus. d’Hist. Nat. 
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