BY R. J. T1LLYARD. 709 



Text-Fig. 112. 

 Phylogenetic Diagram for the Orders of the Panorpoid Complex, as worked 

 out on the characters of the wings only. The small numerals repre- 

 sent the geological and phylogenetic positions of the following im- 

 portant fossil types: — / , Permochorista (Upper Permian of Belmont, , 

 N.S.W-); 2, Belmontia (Upper Permian of Belmont, N.S.W.): j, 

 Jriadosialis (Lower Trias of Germany); ./, Mesochorista (Upper 

 Trias of Ipswich, Q.); 5, Aristopsyche and allied genera (Upper 

 Trias of Ipswich, Q.); 6, Arcliipanorpa (Upper Trias of Ipswich, 

 Q.); 7, Archepsychops and Protopsychopsis (Upper Trias of Ips- 

 wich,-Q.) ; S, the Palaeontinidae .(Jurassic of England and Bav- 

 aria); q, the Kalligrammatidae (Jurassic of Bavaria); 10, the 

 Liassic Diptera; and //, the Necrotaidiidae (Lias of England and 

 Germany). The vertical columns represent ,the consecutive geo- 

 logical ages, from Lower Permian up to Recent. The black lines 

 showing the descent of the various Orders are made to vary some- 

 what according to the abundance of species in each Order at differ- 

 ent geological horizons, and are shown as broken lines where the 

 evidence is not sufficient to allow of a definite decision. 



of the more important of these, in fixing the pliylogenies of 

 the various Orders. Where the line of descent of any given 

 Order is shown as a continuous black line, this indicates that 

 there is a reasonable amount of certainty that this line is cor- 

 rect. "Where the line of descent is shown broken, then there 

 is no reasonable certainty, either as regards the character of 

 the ancestry, or as regards the geological time at which the 

 Order began to evolve. The widths of the black lines, indicat- 

 ing the various lines of descent, are made to vary somewhat in 

 proportion to the relative abundance in species of the Orders 

 which they represent, at each geological period. 

 The following conclusions appear to be justified: — 

 The Archetype of the Complex, which may, be defined as that 

 group of closely related forms from which all the Orders of the 

 Complex arose, must have existed in the I^ower Permian, and 

 possibly even in the Upper Carboniferous. As far as its wing- 

 venation is concerned, it may have been a specialised offshoot 

 from either the Pakeodictyoptera or the Protorthoptera, both 

 of which show closely similar types of wing- venation . It seems 

 fairly certain that this Archetype is not represented by any 

 known fossil, and it is probable that it arose in some part of 

 the world far removed from any of the known insect-bearing 

 beds of the Carboniferous. 



