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Kukalovd-Peck — Palaeozoic Insect Orders 
249 
Protohymen permianus Tillyard (1924) for projections. In all three 
specimens the bases of projections are present and very similarily dis- 
tributed as in Bardohymenidae. However, they merge with the un- 
even surface of the rock to such an extent that they would be 
undetectable unless a well preserved specimen, such as the type of 
S. sibiricus n.sp., were available for comparison. By delicate prepara- 
tion of the surrounding matrix I was able to uncover remnants of 
projections (P. readi , specimen 3257, Museum of Comp. Zoology, 
Harvard University; P. permianus , specimen 5053, Peabody Museum^ 
Yale University), which are prolonged and backwardly curved. This 
fact is very significant, because in Sylvohymen sibiricus n.sp. ( Bardo- 
hymenidae) the projections continue into the covering matrix and 
cannot be followed. 
The projections in Bardohymenidae and Protohymenidae are ar- 
ranged in transverse rows. By position and distribution they are very 
similar to denticles in the transverse carinae of Odonata. In my 
opinion, these structures may be homologous. Besides, some anisop- 
teran nymphs (for instance Erpetogomphus designatus , Gomphidae) 
Needham & Westfall, 1955, bear, on several abdominal terga, paired 
darker pits, located along the median line precisely like the bases of 
the large paired projections in Bardohymenidae and Protohymenidae. 
This similarity is suggestive of possible musculature inside the paired 
projections in Megasecoptera. 
Genera included: Bardohymen G. Zalessky, 1937 (Lower Per- 
mian, Barda River, U.S.S.R.) ; Sylvohymen Martynov, 1941 (Lower 
Permian, Tshekarda, Siberia, U.S.S.R. and Lower Permian, Okla- 
homa) ; Calohymen Carpenter, 1947 (Lower Permian, Oklahoma) ; 
Actinohymen Carpenter, 1962 (Lower Permian, Texas) ; Alexahy- 
men n.g. (Lower Permian, Czechoslovakia). 
Genus Sylvohymen Martynov 
Sylvohymen Martynov, 1941: 10; Carpenter, 1947: 31; Carpenter, 1962: 
37; Rohdendorf, 1962: 68. 
Type species: Sylvohymen robustus Martynov, 1938 (OD). 
This genus is based upon a distal part of a wing from the same 
locality (Tshekarda) as the presently described specimen of Sibiricus, 
n.sp., which is much more fully preserved. Carpenter (1946, p. 31, 
fig. 7) described S. ingens from the Lower Permian of Oklahoma, 
also based on a distal wing third. The apical parts of the wing in 
all three specimens resemble each other and the species cannot be 
separated generically as far as is presently known. Unfortunately, 
they can also hardly be separated from Bardohymen (this statement 
