1967] 
Alockford — Electrentomoid Psocids 
157 
pit separated from frontoparietal region by a ridge; two median 
veins present in hindwing; Sc rejoining R in forewing; a ridge 
running length of anterior coxa along its antero-lateral surface; 
compound eyes transversely color banded ; a row of spines or denticles 
on anterior carina of first femur; R forked in forewing immediately 
basal to pterostigma; a T-shaped sclerite or homologous structure 
present on subgenital plate; third valvula deeply bilobed; pretarsal 
claw with a longitudinal series of spines, setae, or minute ridges on its 
lower surface. 
It is very difficult to decide which of the above conditions are 
plesiomorphous and which are apomorphous for the Amphientometae. 
Only two methods are available for solution of this problem : com- 
parisons with fossil forms, and comparisons with other modern, pre- 
sumably monophyletic groups of psocids and orders of other insects. 
Comparison with the Permian psocids (Carpenter, 1933) shows 
that the following characters are probably plesiomorphous for the 
order: three tarsal segments; forewing with pterostigma not thick- 
ened, with second anal vein, and with apex rounded; antennal socket 
sunk in a pit, the pit separated from fronto-parietal region by a ridge 
(see Carpenter, 1933, fig. 13) ; Sc rejoining R in forewing. 
Three other groups of psocids are available for comparison : Sub- 
order Trogiomorpha, Group Nanopsocetae, and Suborder Psoco- 
morpha. If they are monophyletic groups not including or included 
within the Amphientometae, they may be compared with the Amphi- 
entometae for testing plesiomorphy or apomorphy of characters. 
The Suborder Trogiomorpha is probably monophyletic on the basis 
of the apomorphous character of considerable reduction of the first 
and second ovipositor valvulae and enlargement of the third valvula. 
The Group Nanopsocetae is probably monophyletic on the basis of 
small size and associated simplification of wing venation. The Sub- 
order Psocomorpha is probably monophyletic on the basis of the 
thickened pterostigma and enlargement of the mesothorax. 
In the classification generally in vogue at present, the Group 
Nanopsocetae is regarded as a sister group with the Amphientometae, 
the two groups composing the Suborder Troctomorpha. Although 
the Nanopsocetae is probably monophyletic, it is necessary to try to 
determine if it is phylogenetically coordinate with the Amphientometae 
or if a subordinance relationship may exist between the two. 
This question can be answered in part on the basis of distribution 
of the nodulus. This structure, the distal junction of veins Cu 2 and 
1 A in the forewing, which bears the in-flight wing coupling device, 
is present in Group Psocatropetae (Suborder Trogiomorpha), 
