238 HANDBOOK OF INVERTEBRATE ZOOLOGY. 



long, narrow, laterally compressed body, which is divided 

 into three well-marked regions. 



1. The head, which is flattened from before backwards, 

 and elongated vertically. It carries the eye, the antennae, 

 and the mouth-parts, and is movably joined, by a short 

 neck, to the second region of the body. 



2. The thorax, which, with the head, constitutes the 

 anterior half of the body. On its lower surface it carries 

 the three pairs of legs, which increase in size from before 

 backwards, the third pair being much the largest. The 

 posterior portion of the dorsal surface of the thorax car- 

 ries the two pairs of wings. 



3. The abdomen, which is a little longer than the head 

 and thorax together, is made up of a series of movable 

 segments without appendages. 



4. The wings. The anterior pair of wings, which are 

 known as the tegmina, or wing covers, are about as long 

 as the body, beyond the posterior end of which they pro- 

 ject. They are narrow, and the anterior and posterior 

 margins are seen, when the wing is extended, to be nearly 

 parallel. When folded upon the body their outer faces 

 are vertical, with the anterior margin below, and the pos- 

 terior or internal edges in contact along the back, the left 

 slightly overlapping the right. 



. With a pair of forceps seize the lower edge of the 

 wing-cover, at about the middle, and gently expand it by 

 pulling it downwards and outwards until it is at right 

 angles to the body. Notice that the surface which was 

 exposed in the folded wing-cover is now uppermost, and 

 the edge which was below when folded -is now the anterior 

 edge or costal margin. 



b. Remove one of the wing-covers for examination. It 

 is a thin, transparent, rather stiff plate of chitin, irregu- 



