EXTERNAL ANATOMY OF INSECTS. 41S 
pended to it by ligament or membrane. To this belong 
most of the tribes of the Orthoptera Order, with the ex- 
ception of the Mantide, the Dermaptera, the Homo- 
pterous Hemiptera, and such of the Aptera as have the 
head distinct from the prothorax.—This section admits 
of a triple subdivision: those, namely, whose head is 
wholly covered by the shield of the prothorax, as in 
the Blattina ; those whose head is partly covered by it, as 
Gryllotalpa, and other Gryllina ; and those whose head 
is quite free, not being at all impeded in its motion by 
the prothorax, as the Dermaptera, Nirmus, Pedicu- 
lus, &c. 
3. The third section consists of those whose head is 
truncated posteriorly, and flat or concave, with a very 
small occipital aperture, and is attached to a neck of the 
prothorax upon which it turns, or is merely suspended 
to that part. This includes the Lepidoptera, Hymeno- 
ptera, Diptera, the Libellulina, &c. in the Neuroptera, 
and the Mantide in the Orthoptera. Three subsections 
at least, if not more, present themselves in this section : 
the first is, of those whose head is united to the protho- 
rax, without the latter forming any neck. ‘To this be-~ 
long the Lepidoptera, Trichoptera? The second is of 
those the upper side of whose thoracic neck is /igamen- 
tous; and here you may range most of the Hymenoptera. 
The third is of those in whom it is a continuation of the 
ordinary integument. In this subsection the Diptera, 
Libellulina and Mantide will find their place. In this 
last section the head appears to turn upon the thorax as 
upon a pivot. 
Before I finish what I have to say on the articulation 
of the head, I must direct your attention to the analo- 
