102 



University of California Publications. [Entomology 



Scudder, contains insects with very different facies, and has 

 been somewhat dismembered by later writers. The characters 

 given by the author of its name may be stated in a few 

 words. The wing possesses an entirely simple primary vein, 

 free from both the anterior and the independents. This char- 

 acter is shared by only the Protodonata and Protephemeridaj 



among the Paleozoic insects. The 

 condition is not always to be 

 made out with certainty in a fossil 

 specimen, and so there may have 

 been errors in identification in 

 this group, but it is not likely 

 that all the cases are errors. The 

 character is not as significant, 

 according to our present conceptions of the veins concerned, 

 as it might be under other theories of venation, but it is about 

 as good as any to be found in such an undifferentiated type of 

 venation. The accompanying diagram (Fig. 36) shows as well 

 as may be the character of the venation in this group. I 

 agree with Scudder that the group has no very evident affin- 

 ities with any existing insects. 



J 



FIG. 36. Diagram illustrating the 

 venation of the Horaothetida;. The 

 abundant and variable cross veins 

 are omitted. 



PALEOPTERINA. 



The characters assigned to this group are shown in Fig. 37. 

 The relatively small size of the first group of independents 

 distinguishes it from the two following families. I am free to 

 confess that this char- 

 acter appears to me to 

 be of very little value, 

 and quite insufiicient 

 to differentiate groups 

 larger than genera. 

 Certainly, in living 

 forms with a neurop- 

 terous venation more 

 would be required. I am inclined to believe that venation 

 does not furnish good grounds for classification among these 

 insects. If we depended upon the venation, it is probable that 

 closely allied forms would be separated and more distant ones 

 united. Such a form as Propteticua shows a body structure 

 that would at once separate it from the mass of the insects of 



FIG. 37. Diagram of the venation of the Piileop- 

 terina, omitting the cross veins and the most vari- 

 able of the longitudinal veins. 



