Mr. J. O. Westwood’s Memoirs, &c. 123 
XXIV. Memoirs on various Species of Hymenopterous 
Insects. By J. O. Westwoop, F.L.S., &c. 
{Read 4th February and 3rd June, 1839.] 
I. On the Economy and Relations of the Genus Xiphydria. 
[Tue various situations in which the genus Xzphydria was arranged 
in the classifications of Latreille, Jurine and Leach, together with 
its intimate relation with the genus Szrex, Linn., and consequent 
importance in the distribution of the Hymenoptera given by Mr. 
MacLeay in the “ Horz Entomologicz,” (in which the Tenthredi- 
nide are removed from the rest and united with the T'’richoptera, 
and Svrex is made an osculant suborder under the name of Bom- 
boptera,) induced me, about twenty years ago, minutely to examine 
the structure of the ovipositor and sting of the chief groups of the 
Linnean Hymenoptera, as well as the preparatory stages of such 
species as presented themselves. And although the general results 
of these inquiries have been given to the Entomologist in my “ In- 
troduction to the Modern Classification of Insects,” a considerable 
number of details and sketches still remain unpublished. The 
discovery by Mr. Cooper of the preparatory stages of the genus 
Xiphydria afforded a very important clue to the solution of the 
question of the relations of that genus, and I accordingly drew up 
an extended memoir, (noticed in the Zoological Journal for 1827,) 
in which the entire structure of the genus, in its perfect and prepa- 
ratory states, was reviewed with reference to that of the adjacent 
groups, and in which the position of the genus was traced, through 
the writings of preceding authors, and the formation of the ovi- 
positor throughout the Hymenoptera especially examined; the 
propriety of the general arrangements of the order investi- 
gated; the situation of the present genus therein discussed, and a 
plan of distribution of the order proposed. During the last 
eighteen years, however, the philosophical investigation of the 
order has made such rapid strides that much of what I had written 
is now rendered useless; I have therefore struck it out of my 
memoir, which is here confined to the details of the structure of 
the insect in its different states, and a comparison thereof with the 
allied genera.—J. O. W. 1845. ] 
By the kindness of my friend, Abraham Cooper, Esq., R.A., 
I am enabled to present my readers with a description of the larva 
of a species of the Hymenopterous genus Xiphydria, which will, 
