123 
Larva of the Hymenoptera. 
seems to have no more than eleven segments* in the vertebral axis, 
but on more accurate examination, and particularly on comparing 
it with the pupa, we discover that in reality it has thirteen, that is, 
the number of the larva. Every annulose animal may be resolved 
into thirteen primary segments, which are thus disposed — one for 
the head, three for the thorax, and nine for the abdomen. Let 
us observe a P/iasma, where the female is apterous and the male 
winged. In many females of this genus we may perceive the 
rudiments of the wings, and consequently the inspection of a 
female will point out to us the structure of the male, considering 
this last as a perfect winged insect. Well, then, the female Phasma 
shows nine abdominal segments, three thoracic, and a head. The 
females of certain Blattce are apterous, and in the island of Cuba 
there is a large species of this genus to be found, under stones in 
woods, whose wings are formed, but so short and truncated as to 
render their possessor incapable of flight. Such insects will also 
prove a winged Blatta to be composed of the above-mentioned 
thirteen segments. The same results are derived from the exa- 
mination of the larva? and females of Drilus and Lampyris. It is 
true that some of the abdominal segments become more or less 
confluent in certain insects, particularly of the analogous orders, 
Hyvienoptera and Diptera. But a little study of their structures 
will point out the nature of such aberrations, and, I repeat, that 
the above is the most correct mode of viewing an insect.” 
We accordingly find, that in all the subsequently published 
works upon the general principles of Entomology, these views of 
Messrs. Audouin and Mac Leay have been adopted, but hitherto, 
with the exception of the papers of Dr. Ratzeburg, to be subse- 
quently noticed, no memoir upon this branch of the science has 
been published ; and yet it is evident that it can only be by a 
minute and careful examination and comparison of the develop- 
ment of the different segments of the same insect, throughout its 
various stages, that we can hope to arrive at a decisive confirma- 
tion of these views. 
It will be seen that Mr. Mac Leay brings forward, as instances 
of full development, various female insects, the males of which 
possess a less amply developed abdomen ; but in the order of 
insects, to which I would more particularly request attention, at 
* Here the unpractised Entomologist should be put upon his guard against the 
incorrect ideas which he would gain upon this subject, from the figures given in 
our two most recent works upon Comparative Anatomy; I allude to l)r. Roget’s 
Bridgewater Treatise, and Dr. Grant’s Outlines of Comparative Anatomy, in which 
a beetle is represented having tire nine abdominal segments equally developed. 
