256 Mr. S. H. Scudder on the Relation of 



They are all allied or belong to the Neuroptera, using the 

 word in its widest sense. At least two of the genera [Plate- 

 ^hemera and Gerephemera) must be considered as having a 

 closer relationship to Pseudoneuroptera than to Neuroptera 

 proper, and as having indeed no special affinity to the true 

 Neuroptera other than is found in Palteodictyoptera. Two 

 others (Lithentomuni and Xenoneura), on the contrary, are 

 plainly more nearly related to the true Neuroptera than to the 

 Pseudoneuroptera, and also show no special affinity to true 

 Neuroptera other than is found in Palajodictyoptera. A fifth 

 (Romotketus) , which has comparatively little in common with 

 the Palgeodictyoptera, is perhaps more nearly related to the 

 true Neuroptera than to the Pseudoneuroptera, although its 

 pseudoneuropterous characters are of a striking nature. Of 

 the sixth [Dyscritus) the remains are far too imperfect to judge 

 clearly ; but the choice lies rather with the Pseudoneuroptera 

 or ^^ ith Homothetus. The Devonian insects are then about 

 equally divided in structural features between Neuroptera 

 proper and Pseudoneuroptera ,• and none exhibit any special 

 orthopterous, hemipterous, or coleopterous characteristics. 



4. Nearly all are synthetic types of a comparatively narrow 

 range. This has been stated in substance in the preceding 

 paragraph, but may receive additional illustration here. Thus 

 Plate])hemera may be looked upon as an Ephemerid with an 

 odonate reticulation ; Homothetus might be designated as a 

 Sialid with an odonate structure of the main branch of the 

 scapular vein ; and under each of the species will be found 

 detailed accounts of any combination of the characters which 

 it possesses. 



5. Nearly all hear marks of affinity to the Carhoniferous 

 Palceodictyoptera^ either in the reticulated surface of the wing, 

 its longitudinal neuration, or both. But besides this there are 

 some, such as Gerephemera and Xenoneura, in which the 

 resemblance is marked. Most of the species, however, even 

 including the two mentioned, show palseodictyopterous charac- 

 ters only on what might be called the neuropterous side ; and 

 their divergence from the Carboniferous Palseodictyoptera is 

 so great that they can scarcely be placed directly with the mass 

 of Paleeozoic insects, where we find a very common type of 

 wing-structure, into which the neuration of Devonian insects 

 only partially fits. For 



6. On the other hand^ they are often of more and not less 

 complicated structure than most Pal(Bodictyoptera. This is 

 true of the three genera mentioned above with peculiar neu- 

 ration, but not necessarily of the others ; and it is especially 

 true when they are compared with the genus Dictyoneura and 



