1920] 



Crampton — Lines of Descent of Lower Winged Insects 



125 



Palseodictyopteroid Superorder (Panpalseodictyoptera) 



Protephemerida, Ephemerida, Protodonata, Odonata, Pa- 



Iseodictyoptera, etc. 

 Plecopteroid Superorder (Panplecoptera) 



Haplopteroida, Plecoptera, Hadentomoida, Embiidina, Der- 



maptera, etc. 

 Orthopteroid Superorder (Panorthoptera) 



Protorthoptera, Grylloblattoida, Phasmoida, Orthoptera, etc. 

 Isopteroid Superorder (Panisoptera) 



Protoblattoida, Blattoida, Mantoida, Isoptera, Zoraptera, etc. 

 Psocoid Superorder (Panhomoptera) 



Psocoida, Mallophaga, Pediculoida, Homoptera, Hemiptera, 



Thysanoptera (?), etc. 

 Neuropteroid Superorder (Panneuroptera) 



Neuroptera, Hymenoptera, Mecoptera, Protomecoptera, 



Paramecoptera, Paratrichoptera, Trichoptera, Lepidoptera, 



Diptera, Siphonaptera, (and possibly Coleoptera and Strep- 



siptera?). 



PANHOMOPTERA PANNEUROPTERA 



PANISOPTERA 



PANPROTURA. 



SYMPHYLA- 

 PAUROPODA 



ANNELIDA 



PANPLECOPTERA 

 PANPLECTOPTERA 



PANTHYSANURA 



CRUSTACEA 

 'TRILOBITA 



lYZOSTOMIDA- 

 ONYCHOPHORA 



Fig. 6. Grouping of superorders in general scheme. 



The interrelationships of these superorders, and their positions in 

 the general scheme, are represented in Fig. G. As is indicated in 

 the diagram, the Annelida represent as nearly as any known forms, 

 the ancestral types giving rise to the Arthropoda. The Myzos- 

 tomida-Onychophora group (including the Tardigrada) arose very 

 near the point of origin of the Arthropoda, but these forms are of 



