244 ENTOMOLOGICAL NEWS. [June, '07 



drclla, and Lcpisma is generally looked upon as very near to the 

 ancestor of all the higher insects. 



Winged insects are usually conceded to have been derived 

 from a single source, but recent authors have arranged them- 

 selves into two camps, according as they regard the original 

 insect to have been Blatta-like or Perla-like. The writer 

 strongly inclines to the latter view. If the BlattaAike ancestor 

 was accepted, however, the only change necessary in the dia- 

 gram would be the location of Blatta in the place of Pcrla and 

 the removal of the latter up the main stem towards Sialis. 



The Odonata and Ephemerida are usually recognized as dis- 

 tinct orders by recent authors, though some would still unite 

 them with the Neuroptera nearer to the Pcrla. The placing of 

 these two groups apart from all other winged insects is an idea 

 originating with myself. The basis for this division is the fact 

 that these ancient groups alone among insects existing since the 

 palaeozoic era have the form of articulation of the wing which 

 permits only a motion in one direction ; all other groups possess- 

 ing structures permitting the wing to lie parallel with the axis 

 of the body when at rest. This differentiation of thorax and 

 wing structure must have occurred in very ancient time ; should 

 the importance of this specialization not be admitted, then these 

 groups would simply be moved closer to Pcrla. 



The Orthoptera are almost uniformly combined into one or- 

 der as is here done with the exception of those who would 

 make a separate group for the Forficulids. The latter group 

 seems to have clearly been derived from a Blattid ancestor. The 

 idea that it might have come directly from such an insect as 

 Japy.v is not, I think, held by any one at the present time. 

 There seems to be nearly as much ground for making six orders 

 as done by Handlirsch as for separating off this one. Accord- 

 ing to the conception here presented there are two groups of 

 large insects which left the water in the palaeozoic era, one 

 Phastna-like which lived on the foliage of plants and gave rise 

 to the Mantids and the saltatorial forms, the other feeding on 

 decaying vegetation on the ground, the ancient cockroaches and 

 the two derived groups represented by Hciiiinicriis and /"or//- 



