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 Avith 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 f . 



The Hymenoptera undergo a complete metamorphosis. Most of 

 their larvae 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, maxillEe, and a lip ; at the extremity of the latter is a 

 fusus for the transmission of the silky material that is to be employed 

 in constructing the cocoon of the nymph. 



Some feed un vegetable substances, while others, always destitute 

 of feet, devour the carcases of Insects together with their larvae, 

 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 Tenthredinetse, 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. M^th. de class, les Hymen, et les Dipt. 



t See Encyc. Method., article /Jarfiaie, where this method is well described and 

 perfected. Jurine has also published an excellent vfork 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 inserted in the Mem. du Mus. d'Hist. Nat. 



