HYMENOPTERA, 209 
other parts of trees and plants, in each of which it first deposits an 
egg, and then a foaming liquid, the use of which, it is presumed, is to 
prevent the aperture from closing. ‘The wounds made in this way 
become more and more convex by the increasing size of the egg. 
Sometimes these excrescences assume the form of a gall-nut, either 
ligenous or soft and pulpy, or resemble a little fruit, according to the 
nature of the parts of the plant that are affected by them. These 
tumours then form the domicil of the larvee which inhabit them 
either solitarily or in society. There they undergo their metamor- 
phosis, and issue from them through a circular opening made in their 
parietes by the teeth of the Insect. Generally speaking, however, 
these larvee live exposed on the leaves of the trees and plants on 
which they feed. In the general form of the body, its colours, the 
exterior disposition of its dermis, and in the great number of feet, 
these larvee closely resemble caterpillars, and have been called false, 
pseudo-caterpillars: but they are distinguished from the latter by 
having from eighteen to twenty-two feet, the number of these organs 
in the caterpillar being from ten to sixteen. Several of these pseudo- 
caterpillars roll themselves up spirally; in others the posterior por- 
tion of the body is arched. In order to become nymphs, they spin a 
cocoon, either in the earth, or on the plants where they have lived. 
There they pass several consecutive months, or even the whole win- 
ter, in their first state, and only pass into that of a nymph a few days 
previous to the one in which they appear as perfect Insects or Saw- 
flies. 
M. Dutrochet, corresponding member of the Académie des Sci- 
ences, has published some observations on the alimentary canal of 
these Insects in the Journal Physique. 
In some, where the antennz consist of but nine joints, and where 
the internal extremity of the two anterior tibize is furnished with 
two straight and divergent spines, the ovipositor does not project 
posteriorly. 
Here the labrum is always apparent, and the middle of the inner 
side of the four posterior tibize is destitute of spines, or presents but 
one. The larve or pseudo-caterpillars have from twelve to sixteen 
membranous feet. 
The antenne, always short, sometimes terminate either in a thick 
inflation in the form of a reversed cone rounded at the extremity, or 
of a button, or inalarge joint forming an elongated, prismatic or 
cylindrical club forked in some males; the number of the preceding 
joints is five at most. 
Those species, in which these organs, similar in both sexes, are 
terminated by a globuliform inflation, or by one resembling a re- 
versed cone rounded at the extremity *, and preceded by from four 
to five joints, and where the two nervures of the superior wings form- 
ing the rib, as far as the callous point, are contiguous, or closely 
* This inflation is formed by the fifth or sixth joint, but which, in several, pre- 
sents vestiges of two or three annular divisions, 
