THE WINGS OF BLATTID^ 



125 



The subcostal trachea. — The subcostal trachea is well-developed; but 

 it is short, extending but little if at all beyond the middle of the length of 

 the wing. Its main stem is distant from the margin of the wing; but it 

 usually gives off nimierous branches, which are more or less forked, 

 towards the margin of the wing. 



The radial trachea. — The radial trachea is well-developed and, like the 

 subcostal trachea, gives off numerous branches which extend towards the 

 costal margin of the wing. The radial sector, however, is greatly reduced. 



The medial trachea. — -The medial trachea is not greatly branched and is 

 sometimes reduced to an unbranched condition. 



The cubital trachea. — -The cubital trachea is either with or without acces- 

 sory branches. In the fore wings of the forms studied, trachea Cui bore 

 many branches. 



The anal trachea;. — Trachea ist A is simple in all Orthoptera studied; 

 it often coalesces at the base with the cubital trachea for a greater or less 



Fig. 117. — Wings of a nymph of a cockroach (After C. & N.). 



distance. The second and third anal tracheae are represented by a single 

 stout stem which is divided into many branches. 



The venation of the wings. — The data given above regarding the 

 tracheation of the wings of nymphs furnish material for determining the 



