HYMENOPTERA. 81 
pieces, 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 underneath 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 ex- 
tremity. 
M. Jurine has discovered good auxiliary characters for the 
distinction of genera, in the articulation of the wings(1) 3 to 
describe them, however, would not be in unison with the na- 
ture of this work, and could not remove the necessity of re- 
ferring to his. We will merely observe that he chiefly em- 
ploys those resulting from the presence or absence, number, 
form and connexion of two sorts of cells situated near the ex- 
ternal margin of the superior wings, which he styles radial 
and eubital. ‘The middle of this margin most commonly pre- 
sents a little callosity called the wrist or carpus. From the 
latter arises a nervure, which running towards the extremity 
of the wing, forms, in conjunction with this margin, the cell 
named radial, that is sometimes divided into two. Near this 
spot arises a second nervure, which also proceeds to the pos- 
terior margin, leaving a space between it and the preceding 
one—this space is that of the ewbitaé cells, the number of 
which varies from one to four(2). 
The Hymenoptera undergo a complete metamorphosis. 
Most of.their larvae resemble worms and are destitute of feet ; 
such, for instance, are those of our second and following fami- 
lies. 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, max- 
(1) Nouy. Méth. de class. les Hymen. et les Dipt. 
(2) 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 in- 
debted to M. Chabrier, for his researches on this matter; they are, however, more 
general in their applicatien. They are inserted in the Mém. du Mus. d’Hist. 
Nat. 
Voie TV.—L 
