No. 391. THE WINGS OF INSECTS. 5 
575 
The cubital trachea of the hind wings varies greatly in form, 
even within the limits of a single family. In the Acrididz it 
is sometimes reduced to an unbranched condition (Fig. 75 Cu); 
in all of the Locustidze known to us it retains the primitive two- 
branched condition (Fig. 76); in Œcanthus (Fig. 78) there is 
a single accessory cubital trachea ; while in certain cockroaches, 
not figured here, vein Cz: is pectinately branched. 
Similar variations in the number of branches of each of the 
other principal tracheæ of the hind wings occur. It is not 
P Fic. 75.— Wings of an Acridid nymph. 
necessary to point them out in detail, as they are sufficiently 
indicated by the lettering of the figures. The most striking 
features are the reduction of the radius, the radial sector being 
at most unimportant, and in some cases entirely wanting, and 
the loss of the costal trachea. 
In the fore wings the anal area is variously modified in the 
different members of the order. In the female Œcanthus 
(Fig. 78) it nearly retains its primitive form; in the Acridid, 
