1922 ] Crampton Relationship of Hemiptera-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 Iiadento- 
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- 
bling the Hadentomoids (Fig. 10); but the Embiid types like- 
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 ol the 
Embiids must have resembled both the Hadentomoids and tha 
Protorthoptera in many respects. The general anatomy of the 
