1976] 
Kukalova-Peck and Peck — Calvertiellidae 
91 
terial in the field of Paleozoic insects is relatively “rich” it is obvious- 
ly not sufficient for any reliable conclusions to be drawn from it. 
However, some hypotheses can be suggested as possible. 
The calvertiellids developed from an ancestor which closely re- 
sembled Carrizopteryx in venation, but had separated stems of 
R, M, and Cu, and narrower wings. The characters of venation 
which appear to be potentially useful for stratigraphy are the fol- 
lowing: the richness of ramification (the branching of venation is 
diminished in advanced forms); the density and regularity of reti- 
culation (reticulation becomes larger and more cross veins are pres- 
ent in advanced forms); and the special features of the anal area 
(anal veins become simple and curved sickle-like in advanced forms). 
All these features developed in succession and progressively from 
the oldest genus, Carrizopteryx , to the youngest genus, Calver- 
tiella. 
The characters which seem to be independently variable and 
under the influence of mosaic evolution or of “latent homology” 
(sensu de Beer, 1971), are the following: the fusion and the form 
of the vein-stems; the degree of “discarding of the CuA” (i.e., how 
close CuA is shifted towards MP to function as a joined double vein). 
Also, the relative width of the wings is apparently independent of 
the stratigraphical occurrence, since Carrizopteryx (Virgilian) 
and then again Moravia (Upper Autunian) are conspicuously 
broad, while Moraviptera (Lower Autunian) and then again Cal- 
vertiella (Leonard) are moderately broad. 
With the scanty information available, a more precise sugges- 
tion of the age of the strata in Carrizo Arroyo would be premature. 
All that can be said at present is that the general character of the 
venation of Carrizopteryx is the most primitive among the Cal- 
vertiellidae and that this may be due to an occurrence in strata older 
than the base of the Lower Permian. 
Figures 6-8 (opposite). 
Fig. 6. Moravia convergens, young nymph; SEM photo micrograph of the wing 
surface with prominent tubercles. Lower Permian of Czechoslovakia. Fig. 7. 
Moravia convergens, subimaginal fore wing base with pteralia of palaeodictyopteroid 
type and the anal brace. Lower Permian of Czechoslovakia. Fig. 8. Moravia con- 
vergens, SEM photo micrograph. Lower Permian of Czechoslovakia. 
