1972] 
Kukalovd-Peck — Palaeozoic Insect Orders 
263 
Md 
Figure 8. Blockdiagram representing section of the beak between A 
and B (see fig. 7), in ventral view. Left part (Md, indicated by bracket) 
is probably the natural inner surface of the mandibular stylet where it 
contacts maxillary stylet. Right part is a composite of several inner sur- 
faces of the hollow mandible. Oval elevations (E) and crescent-shaped 
pits (P) are probably opposite ends of short perpendicular pillars, which 
crossed the mandibular cavity and supported it from inside. Original. 
Lower Permian of Czechoslovakia. 
divided into more robust galea and thin, protruding lacina (fig. 7-L) ; 
the lacinia is located at the inner margin and underneath the galea; 
the lacinia extends beyond the beak and has two inward curved apical 
lobes; the external surface of the maxillae carried fine ridges. 2 
Because the beak is split along the median plane, it presents an 
uniquely favorable occasion to study the inner structure. However, 
it gives little reliable information about the character of the food 
canals. The transverse section of the beak (fig. 8) is actually a com- 
posite of several inner surfaces of the mandibles, all of them carrying 
alternating grooves and ridges, and is slightly distorted by an oblique 
pressure. Because of the uneven level of splitting and slight deforma- 
tion during fossilization, the food canals are not clearly distinguish- 
able. 
The maxillary palpi are robust and overlap with the beak (fig. 6). 
All segments carry a flat-topped longitudinal ridge. The surface is 
covered with a fine rugosity and with occasional irregular grooves. 
The more perfect preservation of the beak in Monsteropterum moravi- 
cum brings an explanation of the “protruding needle-like tips” in the beak 
of Mecynostoma dohrni (Palaeodictyoptera, Mecynostomatidae, Kukalova 
1969, p. 210, fig. 28). The protruding structures are undoubtedly also 
laciniae extending beyond the superimposed pair of mandibles. 
