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[December 
complicated interrelationships (both “vertical” and “hori- 
zontal” in the phylogenetic groupings) make it very difficult 
to decide how to distribute them in the superorders of the 
Holometabola. There are at least two superorders of 
Holometabola, in one of which, the Pancoleoptera or 
Coleopteria (including the Coleoptera and Strepsiptera) , 
the mesothoracic coxae are not divided into eucoxa and 
meron, the mesothoracic postscutellum is not well developed, 
and the cerci are usually not developed, while in the other 
superorder called the Panneuroptera or Neuropteria (in- 
cluding the Neuroptera, Mecoptera, Diptera, Trichoptera, 
Lepidoptera and Siphonaptera) the mesothoracic coxae are 
divided into a eucoxa and meron, the mesothoracic post- 
scutellum is usually well developed, and cerci are frequently 
present. 
The Coleoptera are the most Orthopteroid representatives 
of the Holometabola, and are strikingly similar to the 
Dermaptera in numerous features of the body. It is pos- 
sible that the Coleoptera and Dermaptera were derived 
from Protorthopteroid ancestors which had bodies some- 
what like those of the primitive Isoptera, while the wings of 
their ancestors may have been like those of certain Proto- 
blattid Protorthoptera. At any rate, the wings of the so- 
called Protocoleoptera (such as Protocoleus) are very 
Orthopteroid, and may have been derived from a Protor- 
thopteroid type related to the Protoblattids. 
The most primitive Coleoptera are the Cantharoid 
(Lampyroid) beetles, and the Strepsiptera may have been 
derived from ancestors resembling Cantharoid beetles in 
some respects. The larvae of the Strepsiptera are very 
Meloid in appearance, while the adult Strepsiptera resemble 
Rhipiphorid beetles in some respects, so that it is very prob- 
able that the Strepsiptera were derived from a Coleopteroid 
stock, although the exact character of their ancestors has 
not been determined. 
The Neuroptera have retained the most primitive type of 
venation occurring in any Holometabola (with the possible 
exception of the Mecoptera), and the structures of the body 
of the primitive Sialid Neuroptera suggest that their an- 
cestors had bodies resembling those of primitive Isoptera 
and Embiids in many respects, while the venation of the 
