1968] 
Kukalovd — Mayfly Nymphs 
313 
are preserved as distinct, dark lines and even the convexities or con- 
cavities of the veins are discernible. As shown in detail below, the 
venation of all but one of the nymphal wings is like that in the 
Permian family Protereismatidae and in particular like that of the 
genus Protereisma. 
Family Protereismatidae Lameere, 1917 
This widely distributed Permian family has been found in Permian 
deposits in Kansas, Oklahoma, the Soviet Union and Germany. The 
adults are characterized by having the fore and hind wing homono- 
mous or nearly so; costal brace very well developed; Rs distinctly 
arising from R but coalesced shortly after its origin with MA for a 
short distance. The legs were very long and slender; the cerci were 
well developed and a median caudal filament was present. 
Nymphs have not previously been described in this family. In 
this paper I am giving an account of several nymphs which have the 
venation of the wing pads like that of the wing of the adult Proter- 
eisma. One of the nymphs is from the Lower Permian strata of 
Noble County, Oklahoma, (Midco), which contains several species 
of Protereisma known from adults; specific correlation of the nymph 
with any of these is impossible. The other nymphs discussed below 
are from the Lower Permian deposits in Moravia, in which only a 
single adult specimen, consisting of two overlapping wings, has been 
found ; it is possible that the nymphs belong with this adult but 
there is no way of determining the probability of that correlation. 
For this reason specific names have not been assigned to any of the 
nymphal specimens. 
Protereisma sp. (nymph no. 1) 
This specimen was collected at locality L-15 in the Midco member 
Wellington Formation, Noble County, Oklahoma, by F. M. Car- 
penter (1940). In all probability this is a cast cuticle, although it 
is very well preserved with strong relief ; it does, however, have the 
abrupt bend of the abdomen, characteristic of most of the nymphal 
specimens from Moravia, which look very much like cast cuticles. The 
following is a detailed account of this specimen (text-figures 1 and 2). 
Head slightly narrower than the prothorax; eyes probably of average 
size; mandibles large and very broad distally, with four prominent 
teeth; antennae very slender, segments subequal (length of antennae 
unknown) . Prothorax about as broad as the mesothorax but only about 
half its length ; anterior margin slightly concave ; posterior markedly 
Explanation of Plate 29 
Photograph of Nymph No. 1, Lower Permian of Oklahoma. Length of 
fore wing pad, 5.3 mm. Specimen no. 6311, Museum of Comparative Zoology. 
