266 
Psyche 
[September 
Original: No. 5/1972 (obverse and reverse of the body and basal 
parts of wings; separately reverse of the right front leg) ; Paleonto- 
logical Institute of Charles University, Prague, Czechoslovakia. Col- 
lected in the Lower Permian deposits near Obora, Moravia. 
Summary 
Megasecoptera and Palaeodictyptera, two of the three extinct 
paleopterous haustellate insect orders related to extant Ephemeroptera 
and Odonata, were found to carry fringe-like projections on the 
thorax and abdomen. Both orders include mostly large to very large 
insects with good flying ability, which held the wings outstretched 
when resting. The nymphs were terrestrial, probably arboreal, and 
had articulated wing pads which were oriented obliquely backwards 
(Carpenter and Richardson, 1968). 
The projections are hollow outgrowth of the terga, forming usually 
regular rows along the posterior margin or occasionally also on the 
nota. They are more or less sclerotized, protruding up and back- 
wards from the body. The surface is rugose and with scattered tac- 
tile setae. The projections are simple or richly branched and vary 
from short to very long. They occur in both adults and nymphs. 
As far is known, their morphology is characteristic for separate fam- 
ilies. 
Now, the projections are known in Mischopteridae, Aspidothora- 
cidae, Corydaloididae, Brodiidae, Protohymenidae and Bardohy- 
menidae in the order Megasecoptera and in Homoiopteridae in the 
order Palaeodictyoptera. In their location, they are homologous with 
the dentation on the transverse abdominal carinae, present in all ex- 
tant Odonata and with paired pits on abdominal terga in nymphs 
of Gomphidae. 
Since the projections are obviously a unique and isolated character, 
their function in two extinct Paleozoic orders is obscure. From the 
morphology it might be assumed that they were at least to some ex- 
tent movable and were provided with mechanical sense organs. 
The following additional characters have been added to the knowl- 
edge of Palaeodictyoptera: 
The beak consists of stylets of mandibles and maxillae, the pair 
of mandibles being longer and superimposed. Each maxilla is divided 
into a robust galea and thin lacinia, located at the inner margin and 
underneath the galea. The lacinia has two, inwardly curving apical 
lobes and extends beyond the beak. Mandibular stylets partly overlap 
each other along the inner margin. On contact with the maxillae, 
