116 S. H. Scudder— Devonian Insects. i 
ternomedian and scapular veins for a long distance from the 
base, and in the peculiar structure and lateral attachments of 
the internomedian veins: in the minuter and feebler cross 
venation, however, it has an opposite character. 
e appear, therefore, to be no nearer the beginning of things 
in the Devonian epoch, than in the Carboniferous, so far as either 
greater unity or simplicity of structure is concerned ; and these 
earlier forms cannot be used to any better advantage than the 
Carboniferous types in support of any special theory of the origin 
of insects. All such theories have required some Zoza, Leptus, 
ampodea,or other simple wingless form as the foundation point; 
and this ancestral form, according to Heckel at least, must be 
looked for above the Silurian rocks. Yet we have in the De- 
degraded of the sub-order to which they belong, itself one of 
the very lowest sub-orders. Dyscritus too may be o similar 
character differing from theirs. It is quite as if we were 7 
n 
and 
e Carboniferous insects; they have little in common, 
