1947] 
Early Insect Life 
73 
the present-day may-flies, crawling and fluttering among 
the plants bordering the ponds or swamps in which their 
nymphs developed — inoffensive creatures whose only 
claim to fame is their antiquity and proximity to the great 
ancestor of all insects. They had no defense against the 
more powerful, predaceous insects which developed dur- 
ing the later Carboniferous and Permian, and for which 
they must have been easy prey. 
Related to these Palseodictyoptera was another order 
of ephemerid-like creatures, termed the Megasecoptera. 
They were small to large insects, with a wing expanse 
ranging from one-half to five inches, and, like the Palseo- 
dictyoptera, they were unable to fold their wings over the 
abdomen. Until about 12 years ago they were known 
exclusively from the Upper Carboniferous; many Per- 
mian species have since been found, and it has become 
apparent that the order did not attain its greatest devel- 
opment until that period. They had moderately long an- 
tennae, and extremely long cerci. In the Carboniferous 
species the head was small and short, but in some of the 
Permian types it was prolonged into a rostrum, probably 
much like that of the scorpion-flies. The older forms had 
mandibulate mouth-parts, and this was probably true also 
of the later species. The thorax and abdomen were 
slender, and, in the main, generalized in structure. In 
certain Carboniferous species, however, the prothorax 
was highly modified, bearing conspicuous projections or 
spines, which may have had some protective value. The 
legs of most were of the ordinary walking type, but in one 
Carboniferous genus (. Mischoptera ) the fore legs were 
short and raptorial in form though there are no other 
indications of predaceous habits. The wings were the 
most characteristic structures of the Megasecoptera. In 
most species they were very narrowed basally, and in one 
family they were arcuate, as in many families of living 
insects. Two abdominal structures are noteworthy : the 
very elongate cerci, which surpass in length those of most 
other insects ; and, in certain families, lateral gill-like proc- 
esses, resembling those of the Palseodictyoptera. Nothing 
is known of the immature stages of the Megasecoptera, hut 
