UNUSUAL STRUCTURES IN 
THE PALEOZOIC INSECT ORDERS 
MEGASECOPTERA AND PALAEODICTYOPTERA, 
WITH A DESCRIPTION OF A NEW FAMILY* 
By Jarmila Kukalova-Peck 
Department of Geology, Carleton University, 
Ottawa, Ontario, Canada 
The order Megasecoptera is a representative of the haustellate 
paleopterous insects of the evolutionary line that lived during the 
Pennsylvanian and the Permian. The similarity of wings and body 
structures, such as mouth-parts and genitalia, indicate very close re- 
lationship with the order Palaeodictyoptera. Both groups are pre- 
sumed to have emerged sometime during the Mississippian from a 
common ancestor. While Palaeodictyoptera are usually larger and 
more sturdily built, bearing broad wings with a rich venation and 
prothoracic lobes, Megasecoptera are slender insects with a more 
delicate appearance, with petiolate wings and simplified venation, 
with enlarged thorax lacking prothoracic lobes, and with tapering 
abdomen. 
The present paper deals with an extraordinary morphological 
feature — projections of the body cuticle, which occur in most or 
all Megasecoptera and at least in some Palaeodictyoptera. These arc 
conspicuous processes, which are short to very long, simple or 
branched, and which are distributed in regular rows on the ab- 
domen and thorax. 
A fuller understanding of the morphology of this very unusual 
character resulted from two years of intensive research by Dr. F. 
M. Carpenter and myself, based upon fossil material of Commentry 
(Upper Pennsylvanian, France), Mazon Creek (Middle Pennsyl- 
vanian, Illinois), Obora (Lower Permian, Czechoslovakia), Elmo 
(Lower Permian, Kansas), and now also Tshekarda (Lower Per- 
mian, Siberia). I am deeply indebted to Professor Carpenter, who 
was very helpful in the preparation of this study. 
Until now, the projections have been only poorly known. They 
were at first mostly interpreted as tracheal gills that persisted into the 
♦This study has been supported in part by grant No. GB-27333 (F. M. 
Carpenter, Principal investigator, Harvard University) from the National 
Science Foundation. 
Manuscript received by the editor July 15, 1972. 
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