1976] 
Kukalova-Peck and Peck — Calvertiellidae 
85 
is never present, because it is secreted only during metamorphosis, 
shortly before the emergence of the adult or subadult. The faint 
ridges which indicate a simplified venation pattern on Recent 
nymphal wing pads are not functional veins but are residual surface 
structures. 2) The venation is identical with that of the adult wings. 
In Recent nymphs the pattern of blood channels (lacunae) which 
precede the veins usually approaches the pattern of adult venation 
only in the terminal nymphal instars. 3) The wing pads are freely 
articulated. In the Moravia convergens nymph the free attachment 
is indirectly proven through their easy release from the body after 
decomposition. In Recent nymphs, the wing pads early in develop- 
ment always become more or less fused together with the lateral 
margin of the terga, thus simulating continuous, lateral outgrowths. 
As noted by Carpenter and Richardson (1969), the nymphs of 
Megasecoptera and Palaeodictyoptera were probably terrestrial. 
Equipped with identical mouthparts, they shared with the adults 
the same food and probably the same arboreal habitat. This finds 
support in the strongly cuticularized wing pads of Moravia conver- 
gens, armored with numerous, protruding tubercles (fig. 6). The 
most probable function of the tubercles is protection from abrasion. 
However, later in development, the cuticularized surface of the 
wing pads becomes thinner with an increase in size so that the sub- 
imaginal pre-adults have completely membranous wings (figs. 1,7). 
The same process of thinning was observed in Paleozoic Neoptera 
(Protorthoptera) by Sharov (1957) and is common in Recent insects. 
The wing venation of the M. convergens nymph has many adult 
characters: the tubular, corrugated venation; a well developed cross 
venation; recognizable intercalary sectors; and a distinct color pat- 
tern of oblique, irregular dark stripes (figs. 3, 6, 8). The prominent 
tubercles are restricted to young nymphs, and each carries a single 
hair or seta. These are arranged in rows on all veins as well as on the 
entire surface (fig. 6). The most notable nymphal character is 
the difference in the width between the convex and concave 
branches of the same vein-pairs. Thus, Rl, MA, CuA, and both 
branches of 1A are conspicuously broad, much broader than their 
concave partners Rs, MP, CuP, and branches of 2A (figs. 3, 8). 
The veins are widened into broad vein-sinuses, as in some modern 
insects, i.e., the Embioptera. Since the present specimen is the 
obverse and reverse of the upper wing surface it is not known 
