1895.] The Affinities of the Lepidopterous Wing. 713, 
general characters of these lines are strikingly parallel with 
those exhibited by the Lepidoptera. A more primitive sub- 
equality of the wings, shown among the Lepidoptera only by 
the Jugate, is retained, but there is an obvious tendency 
towards a narrowing of the wings and consequent loss in num- 
ber of veins, this loss being first apparent among the anal 
veins, and radial branches, and the hind wings being the first 
to be reduced. Setodes and other similar forms constitute an 
exception to this general tendency, something as do the Sat- 
urniina among the Lepidoptera, in that a peculiarly expanded 
anal field is displayed, although the venation of the wing is 
considerably specialized, the radial branches being largely 
reduced. The wing and anal area here are not in a primitive 
condition, but display a peculiar sidewise developed specializa- 
tion. The tendency towards the disappearance of the base of 
media (V) is manifest, the stem of the vein in both fore and 
hind wings of Mystacides punctatus and others being represented 
by a mere fold. 
Of interest in the comparison of the trichopterous and jugate 
wings, is the condition of the cross veins. The primitive neu- 
ropterous wings are characterized by the wealth of cross veins ; 
the specialized lepidopter- 
ous wings are characterized 
by the almost total absence 
of these veins. The Juga- 
tæ show more cross veins 
than do any of the Frena- 
te. The usual trichopterous 
wings possess more cross veins than the jugate wing, but the 
manifest tendency is towards their fading out and disappear- 
ance. The wings of Mystacides punctatus, for example, a highly 
specialized trichopteron, shows fewer cross veins than do the 
wings of Hepialus or Micropteryz. In the hind wings of Setodes 
sp. there are no cross veins and but two or three in the fore 
wings. In the disappearance of the cross veins those midway 
between base and apex of wing persist longest ; although 
there is a cross vein between the basal part of subcosta (II) 
and the costal margin of wing which is very persistent (see c. 
vu 
Fic. 6. Fore wing of Panorpa sp. 
