1974 ] 
Kukalova-Peck — Pteralia 
419 
in primitive mayflies are thoroughly examined, their connection with 
the axillary plate can be traced. This is true in many Siphlonuridae, 
especially in the hind wings (fig. 6B). In the fore wing of Siphlonu- 
rus inirus (fig. 6A), the axillary plate is domed in the middle. At 
the anteroproximal angle, there is a short groove, which is also present 
in Palaeodictyoptera (fig. 1, 3). Expanded stems of Sc and R (which 
might in this Siphlonurus be represented by the fused R + M + Cu 
stems) meet at a suture and clearly penetrate the axillary plate. In 
the hind wing of the same species, the groove at the anteroproximal 
angle is reduced to a small pit. R is located at the anterior part of 
the dome and is closely followed by the short stem of M, from which 
MA and MP diverge almost immediately. The short stem of Cu 
basal groove; pa — precostal area; ScAPl — subcosto-anal plate; tf — 
transverse furrow. Lower Permian, Czechoslovakia. 
