1974] 
Kukalova-Peck — Pteralia 
429 
Summary 
In the several paleopterous orders, the “axillary plates” are by no 
means to be considered as fully homologous structures. They are 
formed by fusion of various basal plates, which can eventually vary 
in the degree of fusion and in the individual size within a single 
order (for instance in Palaeodictyoptera, and in Diaphanopterodea). 
There is little doubt that in the hypothetical primitive ancestor of 
Paleoptera the main veins originated from the separate basal plates. 
From this condition, the axillary plate was derived by fusion of the 
following plates : in Palaeodictyoptera, of subcosto-anal plates ; in 
Ephemeroptera, of subcosto-cubital plates; in Odonata, of radio- 
anal plates ; in Diaphanopterodea, of medio-cubital plates ; in Megase- 
coptera, only small subcostal plate remained. 
In spite of the variability mentioned above, the general plan of the 
axillary region and adjacent part of the wings is shared by all paleop- 
terous orders, and certain structures, functionally significant for the 
flight, repeat many times throughout Paleoptera. For instance, sep- 
arated or semi-separated anal plates occur in Magasecoptera, Dia- 
phanopterodea, and Ephemeroptera. A deeply concave furrow cross- 
ing transversely the anal area is found in almost all Palaeodictyop- 
tera and in the Ephemeroptera. Transverse reinforcement of the 
proximal half of the wing formed by coalesced veins and supporting 
cross veins, cuticular thickenings and pigmented stripes is present in 
Odonata and in “odonatoid” (dragonfly-convergent) Palaeodictyop- 
tera, etc. These structures will not be understood until more study 
of the functional morphology has been done, particularly on extant 
mayflies, dragonflies, and on wings in general. 
References 
Brodskyi, A. K. 
1970. Organisation of the Flight System of the Mayfly Ephemera 
vulgata L. (Ephemeroptera). Ent. Rev. Wash., 49: 184-188. 
Carpenter, F. M. 
1933. The Lower Permian Insects of Kansas. Part 6. Delopteridae, 
Protelytroptera, Plectoptera and a New Collection of Protodonata. 
Odonata, Megasecoptera, Homoptera, and Psocoptera. Proc. 
Amer. Acad. Arts & Sci., 68 (11): 411-503. 
1963. Studies on Carboniferous Insects from Commentry, France. 
Part V. The Genus Diafhanoptera and the Order Diaphanop- 
terodea. Psyche, 70(4): 240-256. 
Hatch, G. 
1966. Structures and mechanics of the dragonfly pterothorax. Ann. 
Ent. Soc. Amer., 50: 702-714. 
