84 THE AMERICAN NATURALIST.  [VOL. XXXII. 
Redtenbacher. These names and the abbreviations of them, 
which we shall use in our text as well as in the figures illus- 
trating it, are as follows: 
Costa, C. Media, M. 
Subcosta, Sc. Cubitus, Cz. 
Radius, Æ. Anal veins, 4. 
In designating the branches of the forked veins we have 
adopted the principle of numbering them proposed by Redten- 
bacher and combine the numbers with the abbreviations of the 
names of the veins. Thus, the first branch of radius is desig- 
nated as radius-one; and for this term the abbreviation A: is 
used. 
In numbering the branches of the forked veins, the same 
number ts applied to homologous branches throughout the series 
of orders. It is only in this way that the greatest use can be 
made of the characters presented by the wings in working out 
the phylogeny of groups. 
But, in carrying out this plan, we have found that in certain 
orders, as, for example, the Neuroptera, there is a marked ten- 
dency towards the multiplication of the branches of some of the 
principal veins. It results from this that we find, in each of 
these orders, branches that have no true homologues in other 
orders, although in some cases analogous branches exist. As 
these supernumerary veins do not concern us while we are dis- 
cussing the venation of the typical wing, we will postpone the 
consideration of them. 
It frequently happens that the branches of a forked vein are 
reduced in number by the coalescing of two or more branches. 
In numbering such a compound branch the coalescence is 
indicated by the term applied to it. Thus, in very many 
insects, the second and third branches of radius coalesce 
throughout their entire extent, forming a single branch; this we 
designate as radius-two-plus-three, writing the term thus, R2+3. 
We will postpone for a time the discussion of the nomencla- 
ture of the cross-veins and of the cells of the wing, and proceed 
to a consideration of the.hypothetical type to which we have 
referred. 
