1976] 
Kukalova-Peck and Peck — Calvertiellidae 
89 
wards the posterior margin. The areas between MP-CuA-CuP 
are almost of equal shape and width and much less specialized than 
in other calvertiellids. 
However, Carrizopteryx has a very specialized feature of its own, 
which is not present in either of the other calvertiellids: the fused 
stem of R+M with the adjoined ribbon-like Cu stem (figs. 2, 5). 
Fused stems of R+M repeatedly occur within the Pterygota but 
the combination of R+M and a ribbon-like Cu stem is rare, atypi- 
cal for Palaeodictyoptera but typical for elmoid Diaphanoptero- 
dea (a specialized group of Paleoptera able to flex their wings back- 
wards over the abdomen while resting). However, this morpho- 
logical coincidence does not express any close phylogenetic ties 
and is probably deeply rooted in the common genetic makeup of 
the Paleoptera. 
Carrizopteryx arroyo Kukalova-Peck, n. sp. 
Figs. 2, 5 
Holotype: no. 3157 (hind wing, obverse and reverse), deposited in collections of the 
Department of Geology, University of New Mexico, Albuquerque, New Mexico. 
This species is based upon a well preserved adult hind wing, with 
the very base and the middle part of the posterior margin missing, 
and with a color pattern of irregular oblique stripes. The fusion of 
CuP and 1 A posteriorly, as well as the branching of the anal veins, 
may be individually variable. 
Description. Hind wing: length 31 mm; width 14.2 mm. Posteri- 
or margin with slight undulation between 1 A and CuP and 2 A; first 
branch of Rs originating at mid-wing; MP with two relatively 
narrow forks; proximal branch of MP, CuA and CuP equally dis- 
tant from each other; anal veins undulating lengthwise, with a 
slight tendency toward a sickle-like curvature at their very tips. 
Etymology. The specific name is a noun in apposition, and refers 
to Carrizo Arroyo, the type locality. 
The Evolution of Wing Characters in the Calvertiellidae 
As presently known, the occurrences of Calvertiellidae are scat- 
tered across the western half of the Northern Upper Paleozoic 
continent, and span a time from late Pennsylvanian (Virgilian) to 
late Permian (Leonard). In spite of the fact that the available ma- 
