XIV.—The Changes in the Structure of the Wings of 
Butterflies. By A. Rapctirre Grore, A.M. 
[Read June 2nd, 1897.] 
In the literature relating to the course and position of 
the veins in the wings of Butterflies and Moths, I find 
no recognition of the causes which modify their direction, 
and underlie the changes we observe as they pass from 
a generalized to a more specialized arrangement. As the 
biological progress which these changes indicate must 
depend on dynamical requirements, a mechanical explana- 
tion naturally suggests itself. 
From a study of the butterflies I find that the changes 
take a direction which stands probably in relation to the 
mode of flight, and that the processes themselves may be 
distinguished as follows :—firstly, the reduction by ab- 
sorption of the radial veins ; secondly, the disintegration 
of the median series; and, thirdly, the reduction and 
suppression of veins above the radius and below the 
cubitus. These various modifications are carried out to an 
unequal extent in one and the same group, as well as in 
different groups or families of the butterflies, which are 
here especially discussed. They all appear to have their 
origin in the lepidopterous hindwing, and, according to 
the greater or lesser degree of their expression, the wings 
are said to be specialized or generalized. That they are 
inaugurated in the hindwings is to be explained by the 
greater strain laid upon the latter in supporting the body 
and checking the downward stroke of the forewings. 
As compared with the primaries in one and the same 
individual the secondaries are the more specialized. 
All these changes have apparently as their ultimate 
aim the simplification of the venation, the furcations 
being the result of partial absorption of the veins. The 
proof that these views are generally correct is afforded 
by the fact that in Hepialus the radius of both fore and 
hindwings is five-branched, and that the five-branched 
radius of the primaries in those groups where the radius 
of the secondaries appears one-branched evidently under- 
TRANS. ENT. SOC. LOND. 1897.—pPanTiv. (DEC.) 23 
