May, 1953 
Fig. 312.—Metreturus mature 
nymph, dorsal aspect. 
pecatonica, 
pound eye. The thorax has a pair of finger- 
like, projecting lobes on the lateral margins 
of both the pronotum and the mesonotum; 
a hooklike, median projection is borne on 
the sternum of each thoracic segment; each 
fore tarsal claw is single, long, and slender, 
and each of the middle and hind tarsal claws 
is single, slender, and much longer than the 
respective tibia. Abdominal segments 1 to 9 
have each a pair of acute projections at the 
posterolateral angles; a single, hooklike, me- 
dian projection is present in the center of 
each tergite 1 to 9, and also a small, acute, 
Burks: THe MaAyrtiss or ILLINoIs 147 
median papilla on the posterior margin of 
each of these tergites; each of segments | to 
7 bears a pair of deeply fissured gills, each 
gill consisting of a dorsal member with a 
recurved, ventral flap and a smaller, ventral 
member; the three caudal filaments are rela- 
tively short, the outer ones bearing a fringe 
of setae on the mesal margins only. The 
available material of this genus shows that 
the adult would have three well-developed 
caudal filaments. 
Genotype: Metreturus 
species. 
pecatonica new 
Metreturus pecatonica new species 
FEMALE NYMPH.—Fig. 312. Length of 
body 20.0 mm., of caudal filaments 5.5 mm. 
Entire head and body creamy white, vir- 
tually without dark markings except for the 
brown lines on wingpads indicating paths of 
adult wingveins, vague, brown crossband 
at base of each front wingpad, and light 
brown crossbands on caudal filaments. Head 
with eyes separated on vertex by space three- 
fourths as great as the width of one eye; 
a pair of large and hornlike projections 
arising on face between the antennal sock- 
ets; an oblique and finger-like, projecting 
lobe arising from each gena just ventral 
to compound eye; antennal scape about 
three-fifths as long as pedicel, flagellum five 
times as long as pedicel; clypeus with mar- 
gin acutely projecting on meson, laterally 
cut away so as to expose bases of mandibles; 
labrum, fig. 313, with broad, mesal emargi- 
nation on outer margin; mandibles, fig. 314, 
each with apex broad, bearing seven teeth in 
three groups, molar area wanting; maxilla, 
fig. 316, with apex broad, mandible-like, 
bearing five or six slender, acute teeth; palp 
reduced to a single, small, lobelike segment; 
hypopharynx bilobed; labium, fig. 315, with 
glossa large, rounded, each paraglossa with 
mesal margin straight, lateral margin con- 
vex, palp three-segmented, with apical seg- 
ment relatively minute, apposed to an api- 
comesal projection of second segment. Pro- 
notum with a finger-like projection at each 
posterolateral angle and a pair of small, 
submedian projections at posterior margin; 
hooklike projection in center of proster- 
num; fore femur as long as tibia and tarsus 
(without claw), fore tarsal claw single, 
slender at apex, enlarged near base, one and 
one-half times as long as tibia; mesonotum 
with finger-like, lateral projection at base of 
