1919] Walker: Structure of Orthopteroid Insects' 269 



nized by Handlirsch as belonging to this period, only one of 

 which, the Blattoidea, is represented among the orders of the 

 present age, although four others, viz., the Protorthoptera, 

 Protoblattoidea, Protodonata and Protephemeroidea, appear 

 to be the direct forbears of the Orthoptera, Mantoidea, Odonata 

 and Plectoptera (Ephemerida) respectively. 



A large proportion of the insects of this period are char- 

 acterized by their extremely generalized structure and are 

 regarded by HandHrsch as the groups from which all other 

 winged insects, or Pterygogenea, have descended. These are 

 the Palaeodictyoptera. Their two pairs of ample wings were 

 similar in size, form and venation, the latter being remarkably 

 like the hypothetical type on which the Comstock-Needham 

 system is founded. 



The Protoblattoidea and Protorthoptera are independently 

 connected with the Palaeodictyoptera by forms which differ 

 very slightly from the latter, while, on the other hand, the most 

 primitive Blattoidea, such as Polyctoblatta, grade almost 

 insensibly into the Protoblattoidea. The latter group consisted 

 of more elongate forms than the true Blattids, having a less 

 regularly elliptical outline, and usually a longer prothorax and 

 a more exposed and prognathous head. Some of them, at 

 least, had a well-developed exserted ovipositor. 



The Protoblattoidea died out in the Permian, where the 

 first true Mantids appeared, these differing in venation very 

 little from the former group. 



The Blattoidea are considered to be the forbears, not only 

 of their modern representatives, but also of the Isoptera, 

 Corrodentia (Psocidae), Mallophaga and Siphunculata (Ano- 

 plura). None of these groups are known before the Tertiary 

 epoch, and the fossil record offers no clues as to their relation- 

 ships. Handlirsch is probably correct with respect to the 

 Isoptera, although they may well have arisen at a much earlier 

 age than the Cretaceous. 



The Protorthoptera, which also persisted into the Permian, 

 embraced a considerable number of families and genera. They 

 were elongate forms, some with ambulatory legs and prognathous 

 phasmid-like heads, while others had saltatorial hind legs like 

 those of modern Orthoptera. An elongated ovipositor was 

 present in some, if not all, forms(e. g., Dieconeura arcuata 

 .Scudd.) None possessed stridulatory organs. 



