718 The American Naturalist. [August, 
strongly developed jugum in this mecopterous form bears on 
its free margin four strong backward projecting bristles, while 
a basal expansion of the costal margin of the hind wing bears 
on its free margin four strong backward projecting bristles, 
while a basal expansion 
of the costal margin of 
the hind wing bears two 
long, strong, slightly 
diverging bristles, so 
projecting that one lies 
above the other. When 
the wings are expanded 
the four jugal bristles 
lie between two bristles 
of the hind wing (see c, 
Fig. 10), forming a 
unique tying arrange- 
ment. 
So far as this organ 
is concerned, and for 
that matter, so far as 
concerns the venation 
and the wing clothing, 
the trichopterous wing, 
and the jugate and fre- 
nate types of the lepi- 
dopterous wing may 
Fic. 10. Bases of wings of Panorpa; a, base all have had a general- 
Mad prei ; aa - of hind wing; c, bases of ized prototype very like 
the mecopterous wing. 
In the beginning the wings were independent and obviously 
the frenate type and the jugate type may have arisen, as sug- 
gested by Prof. Comstock, as distinct lines from the un-united 
wing type. But from the known phyletic relations of the Ju- 
gate and Frenatz, and from the conditions presented by the 
trichopterous and mecopterous wings, which I have here at- 
tempted to indicate, the evidence, though as yet most ill-di- 
gisted, suggests strongly, to my mind, the probability of the 
