RHIPIPTERA. 221 
be removed in several respects from the Hymenoptera, I still 
think it is to some of those Insects, such as the Eulophi, that 
they are most nearly allied. 
M. Peck has observed one of the larve—<Xenos Peckti— 
which is found on Wasps. It forms an oblong oval, is desti- 
tute of feet, and annulated or plaited ; the anterior extremity 
is dilated in the form of a head, and the mouth consists of 
three tubercles. These larve become nymphs in the same 
place, and, as it appeared to me when examining the nymphs 
of the Xenos Rossi, another Insect of the same order, within 
their own skin, and without changing their form(1). 
Nature has perhaps furnished the Rhrpiptera with the two 
false elytra of which we have spoken, to enable them to dis- 
engage themselves from between the abdominal scales of the 
Insects on which they have lived. 
They are a sort of @'stri to Insects, and we shall soon find 
a species of Conops that undergoes its metamorphosis in the 
abdomen of the Bombi. 
The Rhipiptera form two genera. 
Sty ops, Kirb. 
The first one observed and instituted by M. Kirby. The superior 
branch of the last segment of the antennz is composed of three little 
joints. The abdomen is retractile and fleshy. 
But a single species is known; it lives on the Andrenz. 
XENOS, Ross. 
Here the two branches of the antennz are inarticulated. The ab- 
domen, with the exception of the anus which is fleshy and re- 
tractile, is corneous. 
Two species of this genus are known, one of which lives on 
the Wasp called gallica, and the other on an analogous Wasp 
of North America, the Polistes fucata, Fab.(2) 
(1) For some observations on this Insect, see a very good Memoir of M. Ju- 
rine, Sen. 
(2) See the Memoir of M. Kirby, Lin. Trans., XI. 
