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Psyche 
[June 
wing, there is every reason to assume that the anal lobe was present. 
The body is only faintly indicated in the specimen of americanum. 
Handlirsch’s figure depicts the abdomen and the thorax as they seem 
to me to be in the fossil, except that the prothorax is slightly shorter 
and somewhat broader than he has drawn it. I see no indications of 
the head as it was drawn by him; there are some irregularities in the 
rock which may possibly represent part of the head but no definite 
form can be made out and there are no suggestions of the eyes, so 
far as I can observe, in the National Museum specimen. 
Handlirsch established the order Hadentomoidea (1906, p. 692) 
for this genus. He gave no definite diagnosis of the order, his account 
of the group being essentially a description of the individual specimen 
of americanum. However, it is clear from his discussion that he 
placed much emphasis on the apparent similarity of the fore and 
hind wings and on his conviction that the hind wing lacked an anal 
lobe. H is conclusion was that the Hadentomoidea were probably 
closely related to the Embioptera, although showing some affinities 
with the Perlaria. I believe that his conclusions based on the apparent 
absence of the anal area are not valid. The reconstruction of Haden- 
tomum americanum, which Handlirsch included in his account of 
fossil insects in Schroder’s Handbuch der Entomologie (fig. 73, 
p. 143), is highly imaginary, since it shows the legs, antennae 
and mouth parts, none of which are even suggested in the fossil. 
The general effect of this figure, of course, is to increase the 
bizarre appearance of the insect, as conceived by Handlirsch. As a 
matter of fact, the fore wings of Palaeocixius and of Hadento?nu?n 
show striking similarities, which I believe can only be explained by 
close relationship of these genera, at least to the family level. (See 
figures 6 and 7) The media seems somewhat more reduced in Haden- 
tomum than in Palaeocixius, but the vein which is labelled R4 + 5 in 
the accompanying figure of Hadentomum may actually be the anterior 
branch of the media (i.e., corresponding to the vein labelled MA in 
Palaeocixius) . In the orthopteroids and the Perlaria there is much 
individual variation in the amount of fusion between branches of M 
and parts of the radial sector. Unfortunately, we do not know the 
hind wing of Palaeocixius or that of any of the other genera which 
I am now placing in the family Protoperlidae, with the exception of 
the type-species of Protoperla itself. The latter genus is based upon 
a single species known from the hind wing, which shows a definite 
anal lobe, although the lobe is not as large as in most of the Protor- 
thoptera. The venation of the Protoperla hind wing is difficult to 
interpret on the basis of the single specimen known. The media is 
