128 Mr. J. O. Westwood’s Memoirs 
The Tenthredinide, Ichneumonide, and also the genus Urocerus, 
form cocoons in which to pass the pupa state; but Mr. Cooper 
tells me he did not perceive any thing like a cocoon in which his 
pupz had been inclosed. 
In examining the structure of the perfect insect,* I shall not 
enter into a detail of the structure of their trophi, (although those 
of Xiphydria differ both from the Tenthredinide and Urocerus,}) 
as I consider that variations in the general external organization 
of an insect (being clearly indicative of variations in its economy 
and habits) are of greater consequence than variations in the 
structure of its mouth, the latter being in my opinion entirely 
dependent upon the former. Moreover, we know that not only 
do the genera which Latreille has included in the Uroceride differ 
very much in the formation of their trophi, (which that author has 
proved to be of a very anomalous character,) but that there is 
even very great difference in these organs in the species of 
Urocerus themselves. 
The antenne of the female of X. dromedarius have fifteen 
simple joints,{ thus differing from the greater portion of the 
Tenthredinide and agreeing with those of Urocerus, which vary in 
number from thirteen to twenty-four,§ while Oryssus has only 
eleven. They also agree with Urocerus in the formation of the 
basal joints, and with Oryssus in having them much shorter than 
in Urocerus. In Cephus and Lyda there are nearly thirty joints.|| 
In the shape and insertion of the head Xiphydria also agrees with 
Urocerus; and if we examine the trunk or thorax of both genera 
we shall find little (if any) difference, the extraordinary elongation 
in Xiphydria of the manitrunk (which may here with propriety 
be called the neck) only excepted: but even in Urocerus this part 
is distinct (as in fact it is in all the Hymenoptera), and the fore 
feet are always attached to it.4{] Jurine (who has confused the 
* Mr. Curtis has entirely omitted this anomalous genus in his work on the 
genera of British insects. 
+ The trophi of this genus and of Xiphydria, however, agree in being much 
shorter than in the Tenthredinide. 
$ Mr. Kirby (Mon. Ap. Angl. vol. i. 219) says that this species has thirteen 
joints in the antenne. Might not this description have been drawn from a male? 
Jurine says the antennz of this genus have from fourteen to twenty joints. 
§ Kirby, loc. cit. (Sirer). Jurine (p. 76) says from nineteen to twenty-seven 
joints. 
|| Jurine, pl. 7, fig. 1 and 3. 
{ This (the manitrunk of Messrs, Kirby and Spence) is an extremely interest- 
ing part of the insect, as it clearly shows the correctness of the ideas of those 
authors in considering this part, which in the Hymenoptera and Diptera, and one 
