BY R. J. TILLYARD. 269 



into the Order Megaloptera, which will then consist of two Sub- 

 orders, viz , the Sialoidea (aquatic) and the Raphidioidea (terres- 

 trial). The term Neuroptera is now so ambiguous, being still 

 used in present-day writings to indicate so many different and 

 heterogeneous groups of Orders, that I have no hesitation, for 

 the sake of clearness of argument, in substituting the name 

 Planipennia for it, although I do definitely subscribe to the 

 opinion that the name Neuroptera ought by now to be strictly 

 confined to this Order only. 



For tlie purposes of this paper, I shall definitely include my 

 new fossil Order, Protomecoptera, within the Sub-class Panor- 

 poidea, to which it clearly belongs. The type (and so far the only 

 representative) of this Order is Archipanorpa ma<j7iijica Tillyard, 

 from the Upper Trias of Ipswich, Queensland. Whether this 

 type should constitute a new Order, or only a Sub-order within 

 the Order Mecoptera, it will undoubtedly conduce to claritv of 

 argument if we employ the term Protomecoptera in the sense in 

 which I originally defined it (5). 



The scheme adopted in this paper may now be exhibited as 

 follows : — 



Sub class Panorpoidea : 



Orders Protomecoptera (fossil only), Mecoptera, Trichoptera, 

 Lepidoptera, Diptera, and Aphaniptera. 



Sub-class Neuroptekoidea : 



Orders Megaloptera (including the aquatic Sub-order Sialoidea, 

 and the terrestrial Sub-order Ptaphidioidea) and Planipennia 

 ( = Neuroptera, s.str.). 



Section ii. — General Principles. 



Most of the work that has been done in Entomology upon the 

 Phylogeny of any given Order has naturally been carried out by 

 experts upon the Order in question, with litlle reference to out- 

 side Orders. As an example of this, we may cite Meyrick's 

 numerous works on the Lepidoptera, which, apart from their 

 systematic aims, have also attempted to show the origin of the 

 Order, as a whole, from the Trichoptera. In ihe whole of this 

 work, Meyrick makes allusion to only one genus [lihyacophila) 



