HYMENOPTERA. 85 
however, these larve 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 larve closely resemble caterpillars, and have 
been called false, or 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 portion of the body is arched. In order to be- 
come 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 winter, 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 in several consist of but nine joints, 
and where the internal extremity of the two anterior tibiz is fur- 
nished 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 tibiz is destitute of spines, or presents but 
one. The larve or pseudo-caterpillars have from twelve to sixteen 
membranous feet. } te 
The antennz, 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 in a large 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(1), 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 
approximated and parallel, without a wide intermediate sulcus, form 
the genus 
(1) This inflation is formed by the fifth or sixth joint, but which, in several, 
presents vestiges of two or three annular divisions. 
