on various Species of Hymenopterous Insects. 129 
subject a little by giving to Xiphydria the generic name of Urocerus, 
while to the insects which are alone entitled to that name he has 
given the synonymous name of Strea*) tells us that it is in con- 
sequence of the motion of which this neck is susceptible that two 
of the species have been named after the dromedary and camel. 
The trunk (thorax) also of Xiphydria perfectly corresponds with 
that of Urocerus, while the wings, not only of these two genera but 
also of Zyda and Cephus, appear to be formed on the same plan, 
clearly proving that although possessing characters sufficiently dif- 
ferent to form two distinct families, the Tenthredinid@ and Uroceride 
can never be forced into different orders. Again, in the form and 
proportions of the legs there is a complete resemblance between 
Xiphydria and Urocerus. 1 need only mention the shortness of 
the intermediate tibize, the smallness of the fourth joint of the 
tarsus, and more particularly the dilatation of the posterior tibia 
both in the males of Xiphydria and Urocerus, while in the Ten- 
thredinideous genus Creesus both sexes have the posterior legs 
dilated. 
Let us now turn our attention to the structure of the organs of 
oviposition and the uses of the different parts. These organs 
consist of a pair of outer valves or scabbards (valve) and the 
ovipositor (terebra), which latter comprises the sheaths (vaginulz) 
and the saws (terebella).t 
tribe of the Newroptera, is the true analogue of the upper and under sides of the 
(generally called) thorax of the beetles, as perfectly distinct from the collar in 
these orders, which latter part appears however to be wanting in the beetles. The 
under side of the manitrunk is called the antepectus by Mr. Kirby, (Kirby and 
Spence, vol. iii. p.551,—prosternum Aud.,) and its sides turn upwards and nearly 
form a horny covering. Its upper side is formed of a ligamentous mem- 
brane, properly representing the pronotum of the beetles. Latreille (Hist. Nat. 
vol. xili. p. 138) says, that this neck is formed by an elongation of the thighs 
(hanches) of the fore legs of Xiphydria. This is, however, quite erroneous, as 
on separating it from the trunk (which is very easily done) the fore legs are found 
attached to it; and on the under side, at its base, there are a pair of circular aper- 
tures forming sockets, in which the globose basal joint (coxa) of the fore legs may 
work backwards and forwards. 
* Half the confusion in generic nomenclature has arisen from authors em- 
ploying for new genera synonymous names of the genera from which their new 
groups have been dismembered. Surely when an Entomologist thinks it necessary 
to form a new genus he might give himself the additional trouble of finding a new 
name for it, retaining always the old generic name for the typical species of the 
old genus. 
+ There is also another character clearly proving that all these insects are 
formed upon a similar plan, namely, the existence of a pair of minute styliform 
VOL, IV. K 
