80 Intinois NATURAL History Survey BULLETIN 
In Ulmer’s classification (1933: 207), the 
family Oligoneuriidae includes seven genera, 
all, up to quite recently, considered to be 
Palearctic, Neotropical, or Ethiopian in dis- 
tribution. The members of this family, in 
the imago stage, are characterized by having 
the fore wing with vein Sc absent or fused 
with R, the number of longitudinal veins 
ranging from four to seven, and the few re- 
maining crossveins restricted to the anterior 
two to five interspaces; the hind wing has no 
crossveins, or, at most, very few crossveins, 
all restricted to the anterior part of the 
wing. The median caudal filament may be 
well developed or vestigial. In the nymphs 
of the Oligoneuriidae, the fore femur and 
fore tibia have each a dense fringe of long 
setae on the inner side; the gills of the first 
abdominal segment are large and situated 
on the venter, the gills of the following six 
segments are small, flat, and slender, and 
are dorsal in position. Each cercus bears a 
fringe of long setae on the mesal side only; 
the median caudal filament is either well 
developed or vestigial. 
15. OLIGONEURIA Pictet 
Oligoneuria Pictet (1845:290, pl. 47). 
In the fore wing of the known adults of 
this genus, vein M is unbranched, veins Cu, 
and Cu, diverge near the center, and Rs 
diverges from R near the base of the wing, 
fig. 183. The median caudal filament is well 
developed. 
Oligoneuria ammophila Spieth 
Oligoneuria ammophila Spieth 
(1937: 139; 1938a: 1). 
This species is known only from the 
nymph. It may be that, when the adult is 
found, the generic assignment will have to 
be changed. A complete description of the 
nymph is given by Spieth (1937:139). 
Length of mature specimens 10-12 mm. 
This nymph, fig. 184, bears gill tufts on the 
maxillae. All the abdominal gills are single: 
each gill of pair on segment 1, fig. 184, large, 
finely dissected, and located on the ventral 
side in such a position as to project anteriorly 
between the hind coxae; gills of segments 
2-7 small, simple, obovate, with acute apexes, 
and dorsal in position. 
The nymph of ammophila holds its legs in 
a most unusual position: normally, the fore 
Vol. 26, Art. 1 
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Fig. 184.—Oligoneuria ammophila, nymph, 
dorsal aspect. Small figure at right shows 
detail of gill of first abdominal segment, borne 
on venter. 
legs are held close to the mouth opening, be- 
neath the head; the middle legs extend al- 
most straight posteriorly, beneath the thorax — 
and basal abdominal segments; the hind legs 
extend laterally from the metathorax, at 
right angles to the longitudinal axis of the 
body. In this position, the middle legs extend 
much farther posteriorly than do the hind 
legs. Such an arrangement of the legs 
probably fits the nymph to maintain its foot- 
ing in the rather loose sands in which it has 
been found to live. As is shown in fig. 184, 
only parts of the coxae and trochanters of the 
middle legs are visible from the dorsal as- 
pect. 
