258 ENTOMOLOGICAL NEWS. [June, 'l6 



primitive of winged insects, although in other respects they 

 are decidedly specialized. They are to be regarded as a 

 markedly aberrant group related to the Neuropteroid insects, as 

 well as to the Libelluloid and Perloid lines of development. 

 They appear to approach as closely to the Lepismoid forms as 

 to any of the Apterygotan insects, and the immature stages of 

 Heptagenia and He.vagenia are strikingly Crustacea-like in 

 certain respects (such as the mouthparts, etc.) as will be dis- 

 cussed in another paper. The Ephemeroid forms constitute 

 the order Plectoptera of Packard. 



The Neuropteradelphia form a section of the class Insecta, 

 containing the Neuroptera and those insects which have de- 

 scended from forms not unlike the ancestors of the Neurop- 

 tera. As was mentioned above, the Neuropteroid forms are 

 related to the Ephemeroid group as well as to the Libelluloid 

 group, and also approach the Plecopteron (Perloid) line of 

 descent. The Neuropteron line of descent not only approaches 

 that of the Plecoptera but also approaches the line of the 

 Blattids and Mantids from another angle, which cannot be 

 shown in the diagram, since it would be necessary to draw the 

 Neuropteron line in a plane perpendicular to that of the dia- 

 gram, in order to bring out this double relationship. The rela- 

 tionship of the Neuropteron group to the Plecopteron (Perlid) 

 group is somewhat closer than that of the Neuropteron group 

 to the Blattid-Mantid group ; and the resemblance between the 

 Neuroptera and the Blattid-Mantid group may possibly be due 

 to the fact that both are related to the Plecopteron group in 

 other words the Neuroptera may be related to the Mantids 

 through the mediation of the Plecoptera. A comparison of 

 certain Mantid forms (such as Mantoida Inteola) with cer- 

 tain Neuroptera, however, has led me to think that the 

 Mantids, Perlids and Neuroptera may form the three apices 

 of a triangle, each apex of which is connected with the other 

 two by mutual bonds of relationship, so that the relationship 

 between the Neuroptera and the Mantids is possibly more di- 

 rect than through the mediation of the Plecopteron group, to 

 which both are related. 



( To be continued) 



