576 EXTERNAL ANATOMY OF INSECTS. 
separate motion,—it is nearly a right-angled triangle, 
and is divided longitudinally into two unequal portions. 
In the Orthoptera Order it usually consists of two equal 
portions, and its direction is sometimes nearly horizon- 
tal, as in Mantis and Phasma ; sometimes forming an 
angle with the horizon, as in Blatta ; and sometimes 
nearly vertical, as in Locusta. In the two first cases 
the wings are before the legs, and in the last their po- 
sition is over them. In the Heteropterous Hemiptera 
it is parallel with the scapular, is divided into two un- 
equal portions, and its direction is more or less inclined 
to the horizon *. As to the Homopterous section—in Ful- 
gora it is of avery irregular shape with an angular surface, 
and its direction from the leg to the wing is first nearly 
vertical and then horizontal: in Cicada it is almost 
vertical, and consists of two nearly equal portions. ‘To 
come to the Neuroptera—in the Libellulina it consists of 
two pieces, like those of the scapulars, but smaller °, and 
its inclination is towards the head: in Panorpa also it 
resembles the scapulars both in form and other circum- 
stances °. In the remaining Orders it exhibits no very 
remarkable features. 
16. Metasternum*. The central part of the mesoste- 
thium when elevated or porrected, or otherwise remark- 
able, is called the metasternum. In the Coleoptera, in 
those cases, as we have seen above‘, in which the me- 
dipectus and postpectus form one piece, its anterior point 
becomes the mesosternum ; but in others, as the Preda- 
ceous and Capricorn beetles, &c., it is received in a sinus 
or fork of that part, or meets it. It is usually neither 
* Pirate XXIX. Fic. 15. 2’. > Prate IX. Fic. 8. 2’. 
© Prates VIII. IX. a t. * See above, p. 560. 
