1976] 
Kukalova-Peck and Peck — Calvertiellidae 
81 
Odonata, but are expressions of a genetically based “latent ho- 
mology” ( sensu de Beer, 1971); they occur independently and to 
lesser extent throughout the Paleoptera. 
The family Calvertiellidae has previously been known only from 
the separated single fore and hind wings of adults. This paper 
describes the fore wings of a young nymphal instar and of a sub- 
imago from the Lower Permian of Obora, Czechoslovakia, and 
the hind wing of an adult from New Mexico, and briefly discusses 
the ontogenetic development of Paleozoic nymphs. 
Concerning stratigraphy, the calvertiellids are distributed 
throughout Lower Permian strata; Moraviptera recticulata Kuka- 
lova was found in very early Lower Permian and Moravia con- 
vergens Kukalova in early Lower Permian in Czechoslovakia, and 
Calvertiella permiana Tillyard in late Lower Permian of Kansas. 
The specimen described here as Carrizala arroyo n. g. and n. sp. is 
the oldest known representative of the family, from the late Pennsyl- 
vanian of New Miexco. An attempt is made to identify those wing 
characters which tend to change successively with time, and to dis- 
tinguish them from features which are more independently variable. 
Adults and Pre-adults of the Calvertiellidae 
Adult wings of Paleozoic Paleoptera have a straight or almost 
straight anterior margin and are held at right angles to the body. 
The nymphal wings are easily distinguishable by the characteris- 
tic “nymphal bend” at which the wing axis is turned more latero- 
posteriorly by the convex curvature of the anterior margin and the 
concave curvature of the posterior margin (figs. 1, 3, 4, 8). The 
wing bend was mentioned as occurring in Megasecoptera (Carpenter 
and Richardson, 1969; Kukalova-Peck, 1974) but was also present 
in Ephemeroptera (Kukalova, 1968, see figures) and in Palaeo- 
dictyoptera (Sharov, 1971, see figures; Wooton, 1972, see figures). 
It was probably also present in the still unknown nymphs of Paleo- 
zoic Odonata. During an individual’s ontogeny, the nymphal bend 
becomes successively straightened (figs. 4A and B, 8) with each 
moult until it has completely disappeared in adult wings (figs. 2, 
4C). In Megasecoptera as well as in Ephemeroptera, the nymphal 
bend is located in the proximal third of the wings (Kukalova, 1968, 
see figures; Carpenter-Richardson, 1969, see figures; Kukalova- 
Peck, 1974). In the calvertiellid Palaeodictyoptera and apparently 
