1922] Crampton — Relationship of Hefniptera-Homoptera 27' 



tomoids and Protorthoptera in many respects, their near rela^ 

 tives, the Plecoptera should also be derived from ancestors 

 resembling the Hadentomoids and Protorthoptera in many 

 respects. It is quite possible that the line of development of the 

 Plecoptera branched off from the common Protoblattid- Pro- 

 torthopteron stem very near the point of origin of the Hadento- 

 moid line of descent, or paralleled these lines very closely and 

 the Plecoptera thus inherited characters found in all three of 

 these groups (Protoblattids, Protorthoptera and Hadentomoids) 

 from the common ancestors which combined all of their common 

 characters in themselves. 



As was mentioned above, the Embiid types of fore wings 

 (Fig. 8 and 7) could be readily derived from precursors resem- 

 bhng the Hadentomoids (Fig. 10); but the Embiid types hke- 

 wise approach very closely to the Protorthopteron types of 

 venation, as one may see by comparing the anal, cubital, and 

 median veins of the Embiid shown in Fig. 8, with these veins in 

 the Protorthoptera shown in Figs. 26 and 28. The second and 

 third branches of radius have begun to coalesce in the Protor- 

 thopteron shown in Fig. 26, thus indicating a tendency toward 

 the further coalescence of these veins which has reached com- 

 pletion in the insect shown in Fig. 8; and in the Protorthopteron 

 shown in Fig. 4, the second and third branches of radius coalesce 

 and the fourth and fifth also unite, as is the case with the Embiid 

 shown in Fig. 7. Furthermore, the tendency for all of the 

 branches of media to coalesce exhibited by the Embiid shown in 

 Fig. 7, also occurs in certain Protorthoptera, such, for example, 

 as the one shown in Fig. 30, in which the media consists of but 

 a single branch. From the foregoing facts, it is evident that the 

 tendencies exhibited by the veins of the Embiids could be traced 

 back to Protorthopteron predecessors quite readily. On the 

 other hand, the character of the anals, cubitus, media, radius 

 and subcosta of the Embiids shown in Figs. 8 and 7 is strikingly 

 similar to the branching of these veins in the Hadentomoid in- 

 sect shown in Fig. 10, and I am convinced that the ancestors of the 

 Embiids must have resembled both the Hadentomoids and tho 

 Protorthoptera in many respects. The general anatomy of the 



