42 PROCEEDINGS OF THE ROYAL SOCIETY OF QUEENSLAND. 
both wings whereas in Heteroneura although 5 radial veins are present 
in the fore wing, only two occur in the hind wing. Of the families of 
the Homoneura, so far as may be judged by wing venation alone, Eases 
would fall perhaps closer to the Hepialidae than to any other. In many 
particulars it is closely similar. However, one striking character at 
once separates Eoses from all previously known families of the Homo- 
neura and indeed from all living Lepidoptera, This outstanding feature 
is present in the median veins of both wings. Whereas in all living 
Lepidoptera M 2 is a simple vein, in Eases M 2 is bifurcate. In any dis- 
cussion therefore on this fossil, the study of M 2 is of prime importance. 
Another important character is the separation of M 4 and Cu ia before 
the margin. This also is a distinctive feature, but in as much as 
this has been found as an occasional aberration in individual specimens 
of more than one species of the Hepialidae, e.g., Trictena argent at a and 
Sthenopis, its presence in a supposed ancestral form of the Hepialidae 
would not be a surprising occurrence. 
In other venational particulars, so far as they are preserved in the 
examples available, there can be no strong objection to Eases being placed 
as a member of the Lepidoptera or even in a position on the ancestral 
line leading to the Homoneura and the family Hepialidae. 
The seemingly critical character upon which the classification of 
Eoses should rest is shown to be the presence of both M 2a and M 2 b> a 
double feature found in none of the living forms of Lepidoptera. 
Study of late Palaeozoic members of the Mecopteroid complex shows 
that M 2 is bifurcate in several forms. Permachorista, a genus of the 
order Mecoptera of the Upper Permian of Belmont has this feature 
well defined, and it survives in Jurassic members of the order. 
According to the views of Tillyard, the Upper Permian genus 
Belmontia placed in the order Paramecoptera is the oldest recognisable 
form related to the ancestor of the Lepidoptera. The Paramecoptera 
are a Permian derivative of the Mecoptera and alongside many primitive 
features have developed some specialised characters. Tillyard considered 
that the three great orders Trichoptera, Lepidoptera and Diptera arose 
from the Paramecoptera in the Triassic or Lias. 
While Belmontia does present many primitive features it cannot 
be considered directly ancestral to Eoses , for M 2 is already simple in 
Belmontia. The common ancestor of Eoses and Belmontia must be sought 
rather in those members of the Permian Mecoptera in which this vein 
had not already undergone reduction to the simple condition. Eases 
thus possesses an archaic venational character which separates it defin- 
itely from Belmontia and links it with the Permian members of the 
order Mecoptera. The possible conclusion is reached that Eoses may be 
a Triassic development of and lineally descended from one of the Permian 
branches of the Mecoptera. It is probably not directly related to 
