IIe THE AMERICAN NATURALIST. [VOL XXXII. 
method of increase, which is doubtless as follows : the branches 
have been added one after another to the tip of trachea Rz, 
there being a migration of the base of each accessory trachea 
towards the base of the wing, thus making room for the addi- 
Ca, 
Fic. 53. — Wing of a pupa of Chauliodes. 
tion of new branches. In this case the first accessory vein is 
the proximal one. . 
In Sialis (Fig. 55) the accessory veins have been developed 
in a similar way, but they are on vein R} and on the cephalic 
side of this vein. Here, too, the first accessory vein is the proxi- 
malone. But it should be noted that the numbers of the veins 
increase in the opposite direction from what they do when the 
q ree Jf LULL U LLL 
‘Sc SE ane tin I 
p R, 
Fic. 54. — Wing of a pupa of Corydalis. 
accessory veins are added distally on the caudal side of a prim- 
itive vein, as in the radial sector of Chauliodes and Corydalis. 
Accessory veins added proximally. — A good illustration of 
the adding of accessory veins to the proximal end of a series is 
afforded by the accessories of vein Cur in the Blattide. Fig. 56 
represents the hind wing of a nymph of a cockroach. An 
