1923] 
The Wing-Venation of Insects 
125 
(3A) which we may call the ultimate] each of these six nervures 
is high and has a low sector. 
Consequently we return, in the oldest insects known, to 
that regular alternation of high nervures and low nervures in- 
cluded in Adolph’s old hypothesis. We can even use the 
nomenclature of J. Redtenbacher, accepted by C. Brongniart, 
numbering the nervures from I to XII, the odd numbers 
designating the primary nervures and the even numbers their 
sectors. 
To adapt these ideas to the nomenclature of Comstock 
and Needhan, which is today universally accepted, I propose 
to designate all the sectors by the names of their respective 
nervures, adding to these names the prefix sub. 
Then we shall have in the first group: the costal, high (C 
or I), with the sub-costal, low (Sc or II): the radial, high (R 
or III) with the sub-radial, low (Sr or IV) : the median, high 
(M or V), with the sub-median, low (Sm or VI) and, in the 
second group: the cubital, high (Cu or VII), with the sub- 
cubital, low (Scu or VIII): the penultimate, high (P or IX), 
with the sub-penultimate, low (Sp or X) : the ultimate, high 
(U or XI), with the sub-ultimate, low (Su or XII). 
The sub-radial, the median, the sub-median, the cubital and 
the sub-cubital are each forked twice in the primitive insects, 
giving two limbs and four branches; we have then, adapting the 
the data to the accepted nomenclature: Sr^, SP, Sr^, Sr%; Mb 
Mb M3, Mb Smb Smb Sm3, SmS Cub Cub Cu3, Cm; Scub SciP, 
Scu3, Scm. 
The general evolution of insect wings is characterized by a 
lengthening which is concurrent with a diminution of the breadth; 
this phenomenon has been accompanied by the disappearance of 
certain longitudinal nervures; but these are not the same nervures 
which have disappeared if we consider the two great groups of 
Pterygota; a misunderstanding of this fact has caused a regret- 
table confusion. 
With all the insects whose embryogeny has caused them to 
be called Ectoblastic^ — that is to say the Paurometabola (sensu 
latissimo, the Orthoptera) and the Holometabola, — we have made 
