414 EXTERNAL ANATOMY OF INSECTS. 



pended to it by ligament or membrane. To this belong 

 most of the tribes of the Orthoptera Order, with the ex- 

 ception of the Mantidce, 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 

 Blatta L.; 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, Sec. 



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 Mantidcc 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 belong 

 the Lepidoptera^ Trichoptera P The second is of those 

 the upper side of whose thoracic neck is ligamentous ■ 

 and here you may range most of the Hymenoptera. The 

 third is of those in -whom it is a continuation of the ordi- 

 nary integument. In this subsection the Diptera, Libel- 

 lulina and Mantidcc 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 articidation 

 of the head, I must direct your attention to the analo- 



