1968] 
Kukalova, — Mayfly Nymphs 
3ii 
resentatives of mayfly nymphs, which are, in fact, the only known 
fossil nymphs of the order showing details of wing and body structure. 
In the course of many years of collecting in Lower Permian deposits 
in Moravia (Boskovice Furrow, Obora), I have been able to find 
only six specimens of mayfly nymphs (or their cast cuticles) and 
th ree nymphal wings. Since some of these specimens showed features 
of unusual interest, I brought them with me to make a further study 
while at the Museum of Comparative Zoology. Professor F. M. 
Carpenter, observing my specimens, turned over to me for study 
the few specimens of nymphs which he had collected in Lower Per- 
mian beds in Oklahoma (see Carpenter, 1947). Since these provide 
supplementary information, they have been included in this study. 
As will be shown below, the wing pads turn out to have been quite 
differently attached to the thorax in the Permian nymphs from the 
way in which they are attached in living nymphs. All but one of 
these Permian nymphs belong to the family Protereismatidae, the 
most primitive of all known mayflies with the exception of the Car- 
boniferous Triplosoba j which is represented by only a single specimen 
of an adult (Carpenter, 1963). 
My arrival at Harvard University came at an opportune moment, 
since Professor Carpenter was in the process of studying some fossil 
nymphs from the Upper Carboniferous (Pennsylvanian) nodules of 
Illinois. These turned out to belong to the Megasecoptera and to 
possess wing pads that were attached to the thorax much as in the 
protereismatid mayfly nymphs. The account of these megasecopterous 
nymphs is also being published in this issue of Psyche. 
Most of the fossil mayfly nymphs discussed below apparently con- 
sist of the cast cuticle. This accounts for the distortion of the body, 
as shown in the drawings; in most cases the abdomen is bent at an 
abrupt angle away from the longitudinal axis of the thorax. It also 
explains the composite nature of the fossils; the dorsal and ventral 
surfaces having been pressed together in the process of preservation 
have left impressions of the structural details of both surfaces on each 
of the counterparts. It has proven almost impossible to distinguish 
between the dorsal and ventral structures in the case of the abdominal 
and thoracic segments. For this reason, I have included in the draw- 
ings all of the structures which are preserved, even although some of 
these were undoubtedly on the dorsal surface of the original nymph 
and some on the ventral surface; furthermore, as is usually done, I 
have used both the obverse and the reverse parts of the fossil in 
preparing the illustrations. The clarity of the wing venation in 
some of the nymphal wings is surprising. In some cases, the veins 
