7790 THE AMERICAN NATURALIST. [VoL. XXXII. 
of the branches of the principal veins. In no case is there an 
increase in the number of principal veins. And this increase 
in the number of branches may be confined to one or two 
of the principal veins, while the number of the branches of 
some of the other veins may be reduced, the expanding of some 
parts of the preanal area resulting in a crowding of other parts. 
In some cases we will find that the multiplication of wing-veins 
extends to the anal area also ; in others we will find the anal 
area greatly reduced. But even in those cases where the anal 
area is reduced, the total result has been the production of a 
many-veined wing. 
In the many-veined wings both the longitudinal veins and 
the cross-veins are increased in number. In most cases where 
there are many cross-veins it is impracticable to distinguish 
from others those particular cross-veins to which we applied 
special names in describing the few-veined wings.! But in the 
case of the longitudinal veins it is necessary to distinguish the 
primitive veins, that is, those of our hypothetical type, from 
the veins that have been developed in addition to these. For 
if this is not done it will be impossible to point out the changes 
that have taken place in the course of the development of each 
of the various types of many-veined wings. We therefore 
apply the term accessory veins to these secondarily developed 
longitudinal veins, and retain the same nomenclature for the 
primitive veins that we used in describing the few-veined 
wings. 
Accessory veins may be borne by any of the primitive longi- 
tudinal veins ; and they may arise from either of the two sides 
of such a vein. In most cases it is unnecessary to designate 
the individual accessory veins, as, usually, it will be sufficient 
for descriptive purposes to indicate the number of these veins 
that have been developed upon a particular longitudinal vein. 
In fact, in certain cases more than this could not well be done 
owing to the irregularity of the veins. On the other hand, in 
many cases the accessory veins borne by a single primitive 
vein present a high degree of regularity, and it is evident that 
they have been developed in a regular sequence. Under these 
1 American Naturalist, vol. xxxii (April, 1898), pp. 233, 234- 
