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PROCEEDINGS OF THE ROYAL SOCIETY OF QUEENSLAND. 
2. Suborder Homoneura. 
(a) Family Micropterygidae. 
(b) Family Hepialidae. 
3. Suborder Heteroneura. 
( a ) Family Cossidae. 
(b) Family Castniidae, etc. 
The interrelations of these suborders and the ancestral connections 
of the Lepidoptera cannot of course be shown adequately by a mere list 
and the following diagram may give a more convincing if still very 
sketchy conception of the main relationships : 
Belmontia preserves a record of one of the evolutionary trends of 
Mecopteroid ancestors in late Palaeozoic times, but it is seemingly merely 
a Permian specialisation away from the main Mecopteroid stem. It 
thus loses its high place as a supposedly direct ancestor to the Lepidop- 
tera and Trichoptera and falls into an evolutionary backwater without 
recognised descendants in the Mesozoic. Like the Trichoptera, the 
Lepidoptera seem to have originated as closely allied specialisations 
from an ancestral Permian branch of the Mecoptera. Eoses preserves 
a Triassic phase of this evolution. The trends of development even in the 
Lepidoptera Eoneura were towards reduction of the cross-vein systems, 
reduction of terminal branching of the veins and partial coalescing of 
the apical portions of Cu ia and M 4 . This trend towards reduction has 
continued until Tertiary times. All the main evolutionary trends in 
venation are expressed in modern families by various degrees of 
simplification and reduction from the ancestral Eoneurous pattern. 
