124 
Mr. J. O. Westwood on the Apod 
least in one portion of it, we find the contrary to be the case, the 
abdomen of the male possessing one more segment than the female, 
whilst in my memoir upon the Organization of the Earwig, pub- 
lished in these Transactions, I have shown that the male possesses 
nine fully developed segments, exclusive both of the anus and the 
caudal forceps, whilst two of these, namely, the penultimate and 
the antepenultimate, are greatly reduced in size in the female. 
Now in the apod larvae of numerous Hymenopterous insects, 
which I have lately examined, I have invariably found the body 
to be composed of fourteen segments, excluding a minute por- 
tion often transversely separated from the terminal piece. These 
segments appear to me to be thus constituted: 1st. A head 
composed of a single segment, harder and firmer in consistence 
than the following, being a nearly circular skull, having the 
mouth composed of the ordinary manducatory pieces at its an- 
terior inferior extremity ; then follows a segment destitute both 
of legs and spiracles, which is succeeded by ten apod but spi- 
raculiferous segments, and the body is terminated by two dis- 
tinct and one (as mentioned before) indistinct segments, destitute 
of spiracles. The first three of these segments appear to me to 
constitute the part which will hereafter form the thorax of the 
imago. This opinion being founded, 1st, upon the structure of 
the foregoing segment, which comprises all the requisites of the 
head of a larva: 2dly. Upon the undeniable fact, that in the larva 
it is not necessary that thoracic segments should be provided with 
spiracles; those of Cossas ligniperda and Melolontha vulgaris 
having the second and third of the thoracic segments destitute of 
these organs, although they are provided with legs ; and thirdly, 
because we are thereby enabled clearly to trace the analogy be- 
tween the number of segments of the abdomen of the larva of the 
Hymenoptera, and the fully developed abdomen of the imago of 
the male Forjicula. Moreover, as it cannot be doubted that the 
legs of the larva represent the legs of the imago, so in like manner 
the head of the larva corresponds with the head of the latter ; take, 
for instance, a pedate Coleopterous larva, and compare it with an 
apod one — the only difference is the want of legs, the segments 
being identical; so, likewise, between a pedate Hymenopterous 
larva, and an apod one. 
The paper to which I have above alluded, by Dr. Ratzeburg, is 
published in the sixteenth volume of the Nova Acta Naturae Curio- 
sorum, and is illustrated by a series of figures representing the 
gradual development of the Formica rufa, with additional figures of 
the preparatory stages of Cynips, Ichneumon , Diplolepis, and Apis. 
