The Zygoptera, or damsel-flies, of Illinois

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Illinois State Laboratory

OF

Natural History

Urbana, Illinois, U. S. A.

STEPHEN A. FORBES, Ph D., L,L.D.,
Director

Vol. XII. June, 1917 Article IV.

THE ZYGOPTERA, OR DA MSEL-FL,IES, OF ILUNOIS

BY

Philip Garman, Ph.D.

Bulletin

OF THE

Illinois State Laboratory

OF

Natural History

Urbana, Illinois, U. S. A.

STEPHEN A. FORBES, Ph.D., LL.D.,
Director

Vol. XII. June, 1917 Article IV.

THE ZYGOPTERA, OR DAMSEL-FLIES, OF ILLINOIS

BY

Philip Garman, Ph.D.

/ r.

CONTENTS

PAGE

Introduction 411

Morphology 413-438

Nymph 413

Adult 423

Life history antj habits 438-445

Egg 438

Nymph • 439

Adult 444

History of the' Zygoptera 446-464

Paleontology 446

Ontogeny 450

Phylogenetic comparison of Zygoptera and Anisoptera 453

Classification 464-577

Family Agrionidae 466

Subfamily Agrioninae 466

Family Coenagrionidae 476

Subfamilies: —

Lestinae 477

Coenagrioninae 499

Bibliography 577

Index to genera and species 584

Abbreviations used in lettering plates 586

Article IV. — The Zygoptcra, or Damsel-flies, of Illinois* By
Philip Garman, Ph.D.

Introduction

The order Odonata includes all insects known as dragon-flies in
the broad sense of the term. The adults are characterized by the
possession of fotir membranous, net-veined wings which are of nearly
equal size. The mouth-parts are fitted for biting and the metamor-
phosis is incomplete. The males are distinguished by accessory gen-
italia on the second and third abdominal sterna. The nymphs are
aquatic, and are recognizable and separable from other aquatic forms
by the large hinge-like labium which folds beneath the head. The
order is subdivided into two suborders, the Anisoptera and the
Zygoptera. The adults of the Anisoptera have large, broad wings,
but little contracted at the base and with numerous cross-veins. The
wings of the Zygoptera are usually narrowed at the base and possess
fewer cross-veins. The Anisoptera usually rest with wings spread
horizontally ; the Zygoptera usually with wings held vertically. The
nymphs of the suborders are easily separated by means of the respira-
tory apparatus, the Zygoptera having three tracheal gills at the caudal
end of the abdomen,, and the Anisoptera having no caudal tracheal
gills, being provided with rectal gills instead.

The Odonata form one of the strangest orders of insects with which
an entomologist has to deal. Their bizarre form, striking colors, and
peculiar habits make them an object of much curiosity on tlie part of
the layman as well as the object of many studies on the part of the
scientist. The prevalence of the popular terms, snake-feeders, snake-
doctors, and similar names, shows that there are many superstitions
concerning the group.

As is well known, the Odonata are predaceoiis, in all stages, upon
other insects, particularly upon those insects annoying to man, the
flies and mosquitoes, and in this role thev must be classed as beneficial.
Their harmful activities are few, but they sometimes destroy young
fish, they occasionally injure plants by the insertion of eggs, and,

•Contributions from the Entomological Laboratories of the University of Illinois
No. 53.

412

most serious of all, they do not discriminate between beneficial and
noxious insects, but destroy both. An instance of the fact last men-
tioned is the recently reportetl feeding of Anax Junius on the honey-
bee. In no case, however, is it probable that the harm done overbad
ances, or begins to counterbalance, the good which these insects do
in the destruction of biting Diptera.

The classification of the nvmphs of Zvgoptera is in a backward
state as compared with the classification of the adults. This is due
especially to the fact that immature forms are not easily collected and
that their classification is particularly difiicult. An intensive study
of the nymplial characters has shown that there are, within certain
genera, groups of nymphs the species of which are much more closely
related to each other than to the members of other groups of the same
genus. These groups correspond to groups of adult species in the
identification of whicli the characters of the anal appendages of the
male are mostly relied upon. Little attention seems to have been given
by taxonomists to the females, and where species are represented in
collections by females only it is exceedingly difficult to determine them.
Again, when studying nymjjhs, one is often successful in rearing a
number of females, but almost any amount of painstaking work may
fail to produce a male. In such cases still more inconvenience is
experienced when it is found that the reared females can not be named
because of the fact that the i)ublished synopses are based largely upon
male characters.

It is with a view to clearing up some of the obscure features of
the classification and lessening the labor of determination that nymphs
and adults, including Iiotli sexes, have been considered together and
tables prcp;irc(! for tlie separation of both.

All obtainable biological data have been added for the sake of com-
pleteness; but it is fully realized that the data given here are incom-
plete, and can only be made complete after many years of diligent
study.

Nymphs of several species which are apparently new have been
reared in the course of the study and arc described herein for the first
time. Some of the remaining si)ecies which doubtless occur in Illinois
but wiiich have not been collected by the writer, have been obtained
through the courtesy of various people, and the list has been completed
as far as possible in this way.

Certain proi)lems concerned with the nomenclature have presented
themselves, the most important of which concerns the adoption of
family names. According to the ruling of the International Commis-
sion on Zoological Nomenclature (Muttkowski, 'lo: 15) Agrion re-

413

places Caloptervx, and the family name Calopterygidae must be abol-
ished. The change has caused much confusion because of the former
application of the name Agrionidae ; but it seems practically certain that
further change would only result in still, greater confusion, and the
family names as used by Muttkowski are, therefore, adopted without
change.

The use of the common names "dragon-fly" and "damsel-fly" in
referring to the Anisoptera and Zygoptera respectively, causes no little
confusion because of the frequent use of the term dragon-fly to denote
the order as a whole. In the following pages, the words Anisoptera
and Zygoptera will be used exclusively to designate the subdivisions
of the order.

ACKNOWLEDGMENTS

I take pleasure at this point in expressing thanks for the valuable
aid which Dr. A. D. MacGillivray has given by his careful supervision
of, work and thoughtful criticism during the course of the study.
Thanks are also due to Dr. S. A. Forbes for granting financial support
from the funds of the Illinois State Laboratory of Natural History
as well as for the loan of the collection of Zygoptera belonging to that
laboratory. I am especially indebted to Mr. E. B. Williamson for his
kindness in permitting me to examine his collection of Odonata ; and
I further wish to thank Dr. E. M. Walker and Dr. J. G. Needham
for the loan of specimens of zygopterous nymphs, and Dr. P. P. Cal-
vert for the identification of material sent him.

Morphology

NYMPH

The nymphs are distinguishable from all other insects by the
possession of three more or less flattened, caudal, tracheal gills. They
are slender, delicate insects of the same color as the surrounding veg-
etation or environment in which they live and at first sight seem
hardly capable of the predatory habits of the order. They are usually
covered with fine hairs or spinules which collect an ambuscade of dirt
and rubbish. Their slender cylindrical abdomens resemble the stems
of plants and weeds, and the caudal gills remind one frequently of
growths of algae. Such adaptations as these render the insect most
inconspicuous in its natural habitat.

Head. — The head of the nymph is somewhat oval or pentagonal
in outline when viewed from above, and is usually longer than wide.
The sutures are indistinct even in full-grown nymphs with the excep-

414

tion of the epicranial suture, which is a Y-shaped line on the dorsum
of the head, near the caudal mar.s^in. Sutures are wanting, separating
vertex from occiput, occiput from postgenae, and postgenae from
genae. The vertex occupies that part of the dorsum of the head cap-
sule caudad of the arms of the Y ; and the occiput and postgenae
together, the portion of the caudal aspect of the head not occupied by
the occijiital foramen and the compound eyes. The genae are the areas
mesad of tlie \entral margins of the compound eyes. They fuse with
the postgenae (Fig. 7, pg) near the ventral margin of the head.
Extending caudo-dorsad on the caudal aspect from the ventral articu-
lations of cacli mantlilile, there is a distinct ridge which disappears
near the middle of the head. The trochantins of the mandibles are
present as indistinct triangular areas laterad of the bases of the mandi-
bles (Fig. 7, tm).

Co))ipoiim{ Eyes. — The comjioimd eyes of the nymphs, like those
of the adult, are very large. They occupy perhaps one-third of the
dorsal surface of the head, nearly the whole of the lateral surface,
and part of the ventral. Tlie facets arc hexagonal antl similar to those
of other insects.

Ocelli. — The ocelli are wanting during nymplial life, l)ut in the
later stages the adult ocelli may be seen through the transparent cuticle
of the dorsum of the head. Thus it often appears as if the nymph
had ocelli when in reality there are none present, as: can be proved by
an examination of tlie final exuvium, or l)v dissection.

Antennae. — The antennae, in all full-grown nymphs, consist of
seven segments. The distal segment is short in most species and the
connection Ijetween it and the preceding one is frequently obscure, so
that it seems as if the ai)pendage had only six segments. The first
segment is usually thicker than the remaining ones, and in the
Agrionidae is as long as all the rest of the segments together. In the
Ci>enagrioni(lae, the third segment is the longest and each of the seg-
ments distad of it is shorter than the segment preceiling. The two
proximal ones are not constant in length but are alwavs shorter than
the third.

Mandihle.w — Tlie mandibles are normally hidden from sight by
the large labium and the flap-like labrum. They are located on the
ventral surface of tlie head and are well formed for mastication. They
are irregular in outline, though somewhat rectangular, bearing four
short, strong teetli along the distal margin and several smaller teeth
mesad ami proximad of these.

Maxillae. — The maxillae (Fig. 22) are attached to the ventral
surface of the head and tlie following parts are distinguishable: a

415

triangular cardo (cd) ; a narrow sclerite which may be known as the
cardella (cl) ; and a long, oblong stipes, to the distal end of which
are attached two appendages representing palpus, lacinia, and galea.
The lateral, narrower one of these (mxp), the palpus, bears on its
surface a number of strong setae. There is sometimes a distinct swell-
ing at the base of it but there is no distinct suture between the proximal
and distal portions. The remaining process, regarded as the fused
galea and lacinia (glcj, is much broader at the base and tapers con-
siderably at the apex, where it bears about five strong hooks. It is
provided with two rows of weaker setae extending proximad from
the hooks. The identification of this piece as fused galea and lacinia
is due to the supposed occurrence, in adults of certain species, of a
suture extending across it from the pro.ximal to tlie distal end. So far
no case has come to my notice in which this suture is present, but a
study of Ephemerida (Morgan, '13) and Plecoptera (Fig. 31) on the
other hand, proves conclusively that the piece has been correctly inter-
preted.

Labium. — The labium differs greatly from that of the ordinary
insect in being free from the head at the point of articulation of the
submentum, and in being folded so that mentum and submentum are
appro.ximated when the piece is at rest. It is applied to the ventral
surface of the head, forming a sort of mask ; and an idea of its general
location and shape may be obtained from Figures 1—4, 6, and 7.

Several forms of labia occur in the suborder which, although sim-
ilar in general construction, differ in certain particulars. The forms
of the lateral arms or labial palpi, the mentum, and the submentum
are diff'erent enough in different species to enable one to determine the
family, and sometimes the genus, at a glance (Figs. 8—13). The sub-
mentum is a hollow tube of cuticle (Figs, 2, 4; sm) articulating
at its proximal angles with the ventral wall of the head capsule.
It is filled with muscles for the extension and retraction of
the labium as a whole, and varies in shape ■ from cylindrical
to fliat, and from comparatively short, hardly extending caudad
ol the posterior margin of the head, to long and slender, reach-
ing caudad of the metacoxae. The mentura-Iigula, or median
lobe (Figs. 8, 9; ml), is likewise filled with heavy muscles which
move the labial palpi. It varies in shape, in the degree of the con-
traction proximad, and, more important for purposes of classification,
in the number of mental setae (Figs. 10, 12, 13 ; ms). The median lobe
is sometimes notched or cleft at the apex but is more frequently with-
out indentation. The glossae and paraglossae are present at the distal
end of the labium, but the suture between them and the mentum is in

416

most cases indistinct. The latter, however, seems to he represented in
species having the deeper median clefts. The palpi are present in the
so-called "lateral arms", the distal segments l)eing represented hy the
movable hooks (Figs. 8, 9; Ip:..). The lateral arms also bear a
number of raptorial setae in some species (Fig. lo). In capturing
prey, which consists of mosquito and other soft aquatic larvae, the
nvmi)h swings out the hinged labium, opening and closing the lateral
arms like a pair of jaws. The \ictim is then drawn back toward the
mouth and the heavy maxillae and mandibles finish the work.

Labial Muscles. — The muscles operating the labium have been
studied by few, and studies that have been made seem incomplete. It
has therefore seemed advisable to examine them in detail. The struc-
tures have been determined by means of cross and longitudinal sections
and verified as far as possible by gross dissections.

The median lobe (Figs, i, 2; ml) contains four large muscles for
operating the lateral arms. These are attached proximad directly to
the dorsal wall of the submentum, dorsad of the hinge (Fig. 4). At
the point of attachment to the labial palpi, the muscles are usually
modified to form tendons. With the submentum there are also two
pairs of muscles, which, though not as large as those of the median
lobe, play an even more important part in the operation of the piece.
The points of insertion of the mental muscles are of especial interest
and give clues to the actual function of each muscle. The dorsal
inner pair (Figs. 2, 4) is attachetl proximad to the tentorium and distad
just above the hinge which is between the median lobe and the sub-
mentum. The remaining, or ventral, pair is attached to the chitinous
ligament or rod described below — a structure present only in the
Odonata. The rfid (Figs. 3, 4, 7; cr) is unpaired and is attached to
the ventral wall of the head just caudad of the hypopharynx. It
extends obliquely caudad and dorsad in the plane of the meson and is
attached again to the dorsal wall of the sul)mentum. at which point it
expands in such a way as to form the top of a T. The ventral pair of
muscles are inserted on the base of the chitinous rod (Fig. 4). From
this point they extend over the mento-submental hinge and attach
themselves to the ventral wall of the median lobe. A third pair of
muscles, present at the base of the submentum, is attached to the ventral
wall of the head caudad of the hypopharynx, extends caudad and
dorsad, and is inserted on or near the tentorium.

The exact function of each of the muscles contained in the sub-
mentum is diflicult to explain, and it is probable that no single pair
can be said to produce a given result with the exceptioruof those operat-
ing the labial palpi. Thus it can be seen that the oblique muscles at

417

the base of the labium are important in throwing the siibmentum away
from the head. In this, however, they are aided by the presence of
the obHque, chitinous rod and by the contraction of the dorso-sub-
mental muscles. The action of the ventral pair seems reasonably clear,
as it can, by contraction, swing the mentum back towards the sub-
mentum, and by action in conjunction with the chitinous rod, swing
the submentum back towards the head. The mentum is swung out
away from the submentum mainly by the action of the dorsal sub-
mental muscles which are attached to it above the hinge and in this
capacity are aided to some extent by the contraction of the muscles
within the mentum, especially those which operate the labial palpi.

Glossae and Paraglossae. — -^he glossae and paraglossae are fused
and the suture is untraceable except in the embryo (Butler, '04). The
n3miph of Agrion shows a fold extending between the labial palpi
beneath the median cleft. This fold probably represents all that is
left of the suture between mentum and paraglossae. In other species
the course of the suture is marked b}^ a row of setae, the mental setae.
The area occupied by the submentum is indefinite, but it is probable
that the mental setae, even if secondary in origin and occurring only
in the more specialized forms, are near the location of the original
mento-paraglossal suture. The latter suture has been thought to
become approximated to the distal border of the median lobe, but this
seems doubtful after comparisons of nymphal and embrvonic labia
(Butler, '04).

Labial Palpi. — The palpi of the labium are represented bv the lat-
eral lobes, (Figs. 8, 9; Ipi, lp2). These lobes bear at their distal ends
a. number of fixed hooks, which are simple in some cases, but may
become modified in others, for instance in the Coenagrionidae, in
which the middle hook is replaced by a blunt process with teeth at
the apex. That the fixed hooks have not the same origin as the mov-
able ones, is shown by the fact that the latter bear, in certain nymphs,
a number of long setae. The movable hook has been considered (But-
ler, '04) as a modified palpal segment, and this interpretation is un-
doubtedly the correct one. The proximal segment or body of the
lateral arms also bears in many species of nymphs a row of long setae,
the number of which is used extensively in the classification of the
group. In Agrion, however, this row of setae is wanting and the lat-
eral lobe bears only two small setae near the base of the movable hook.
The body of the mentum is also provided with rows of setae in all
genera except Argia, Agrion, and Hetaerina, the bristles being in two
divergent lines beginning near the meson slightlv distad of the center
and reaching nearly to the proximal end of the labial palpi.

418

Median Lobe. — This term is used for convenience and includes the
fused glossae and paraglossae.

Hvpopluirvnx. — Perliaps the most conspicuous ])ortion of the
hypopharynx is a circular pad between the tips of the maxillae, and
easily seen on raising the mentum-ligula. It is covered with minute
setae possibly indicating the location of sensory organs. The pad has
been given the name laniinula !)y Uerlese, and corresponds to the lingua
of other insects. However, it is somewhat difficult to homologize any
part of it with other forms on account of the very great modification.

Propharxnx. — The propharynx lies closely applied to the ental sur-
face of the labrum, and has essentially the same shape as the latter.
It possesses no features worthy of mention.

Prothorax. — The prothorax, the large segment just caudad of the
head, is preceded liy a smaller segment, the microthorax, which forms
the neck. The sclerites of tlie microthorax are not well developed in
the nymph. Most of the sutures of the prothorax are also indistinct
and are represented by furrows in the cuticle. The pronotum (Fig.
23, pme) is divided by depressions into caudal, mesal, and cephalic
areas. The caudal lol)e is, in most species, a narrow transverse area
along the caudal margin; the mesal lobe comprises the larger part of
the pronotum, and is usually divided by a median furrow into two
lateral areas; and the cephalic lobe includes the transverse area
cephalad of the median lobes rind caudad of the cephalic margin. The
furrow which marks the caudal boundary of the cephalic lobe and the
median furrow of the pronotum form a Y, and at the point of union
of the three arms there is usually an invagination. The proepimera
and proepisterna are areas vcntrad of the pronotum on cither side and
dorsad of the coxae, and are separated by furrows which are very dis-
tinct in some genera, especially Lestes. In this genus the furrow sep-
arating the two pieces extends dorsad a short distance from the point
of articulation of the procoxae and the procoxal process (P'ig. 25,
pcxp), bends slightly cephalad and then caudad, extending to the caudal
margin of the prothorax. In the Coenagrioninae there is often a sec-
ondary ridge extending dorsad from the procoxal process but this does
not mark tlie boundary between ])roepisternum and procpimcron. The
prosternum is the area between tlie procoxae, and is much broader than
that of the adult. There is no indication of distinct areas or sclerites,
but near the caudal margin of the prosternum and between the coxae
are the two invaginations of the furca (Fig. 24, fi).

Mesothorax and Mctathorax. — The mesothorax and metathorax
are greatly different from the common type of thorax, in consequence
of an approximation of the mesepisterna on the dorso-meson in the

419

mesothorax and an approximation of the epimera on the ventro-meson
in the metathorax; all of which is accompanied by an enormous de-
velopment of muscles within the thorax in preparation for the active
life of the adult. The wing-cases, too, are early approximated, and
there is a corresponding reduction in the size of the mesonotum and
metanotum.

Mesonotwn. — The mesonotum is divided into two regions by the
closing together of the mesepisterna. The cephalic one, the prescutum,
just caudad of the pronotum, is a shield-shaped plate with slightly
projecting cephalo-Iateral angles. On the cephalic margin of this piece
on the meson there is an invagination, the prephragma, which, how-
ever, is usually not well developed in the nymph. The second portion
of the mesoscutum lies between the cephalic pair of wing-cases. This
represents combined scutum, scutellum, and postscutellum. It is nar-
rowed cephalad, has a sliglit projection on each cephalo-Iateral angle,
the anterior wing-processes (Fig. 21, awp), and a similar, longer, one
on each caudo-lateral angle, the posterior wing-processes (Fig. 21,
pwp). Near the cephalic margin on the meson is an invagination indi-
cating the location of the mesophragma. Immediately caudad of the
mesoscutum and between the second pair of wing-cases is the
metascutum. This is similar in shape to the caudal sclerite of the
mesoscutum, though somewhat larger, and possesses similar wing-
processes on its lateral angles. There is no subdivision of the
metascutum, but there is a deep invagination on the meson near the
cephalic margin— the metaphragma.

Mcsothoracic Spiracles. — These are located just laterad of the
prescutum and are always hidden to a greater or less extent by the
overlapping pronotum. Large tracheae are connected with them and
the spiracles are doubtless functional during nymphal life. The meso-
stigmal plates are wanting in the nymph, and their derivation will be
discussed later, in the description of the adult.

Mesopleura. — These sclerites, occupying somewhat more than the
cephalic half of the lateral aspects of the pleura, are approximate on
their dorsal margin between the prescutum and the wing-cases. The
dorsal border extends from the mesostigma caudad to the second pair
of wing-cases. The cephalic margin follows the'caudal margin of the
pronotum and extends ventrad from the mesostigma to the mesocoxae.
The ventral border follows the contour of the coxal cavity; and the
caudal border, forming a suture which may be known as the inter-
pleural suture (Fig. 25, insu), extends from between the mesocoxae
and metacoxae dorso-caudad to near the base of the second pair of
wings. The mesopleura are each divided by three furrows into three

420

areas, two of which, the cephalo-dorsal and cephalo-ventral (Fig. 25,
seps, ieps), comprise the episterna, and the caudo-ventral, the epimera
(Fig. 25, epm). The ventral areas of the episterna (ieps) are known
to odonatologists as the infraepisterna, and the dorsal ones incorrectly
as the episterna. For convenience in designating the parts the latter
may be known as the supraepisterna (seps).

Mesostcrnum. — The mesosternum, that area between the meso-
coxae, the caudal margins of the prosternum, and the cephalic margins
of the metasternum, is not divided into separate areas, but the furcae
are present and the deep f ureal invaginations are very distinct (Fig.
24, fi).

Mctaplcura. — The boundaries of each metapleuron are the inter-
pleural suture, the metacoxae, the metathoracic wing-cases, and the
pleura and sternum of the first abdominal segment. The sclerites are
each divided into three parts, the cephalic two comprising the
metepisternum (supraepisternum and infraepisternum), and the caudal
one, the metepimeron. The metathoracic spiracles are located on these
pieces near the union of the dorsal border of the metinfraepisternum
with the interpleural suture.

Mcfasfcriiuiu. — The metasternum (Fig. 24, mtst) is similar in
shape to the mesosternum, but is divided by sutures into three areas.
The invaginations of the meta furcae are also prominent and a suture
extends caudo-mesad from each. The two sutures unite on the meson,
extend caudad for a short distance, separate again, and extend laterad
and caudad of the coxae. The areas on each side of the mesal line are
the two halves of the sternellum (mtsm). Caudad of the sternellum
is a broad sclerite possibly representing the first abdominal segment.
This may be known as the intersternum (Fig. 24, ints). There is no
corresponding sclerite on the dorsum caudad of the thorax, but it may
be that the latter portion has been lost. If, however, the intersternum
be considered as a vestige of an abdominal segment, it will be found
by actual count that there are twelve segments represented in the abdo-
men of the nymph, a fact which makes one skeptical of the above inter-
pretation. In some species, the area is membranous, and it is possible
that the sclerite is nothing more than accessory' membrane which has
subsequently become chitinized.

Trflcltantiiis. — The trochantins are wanting in the Zygoptera, and
the mesal part of the coxae articulates directly with the sterna.

Legs. — The legs are usually slender and not well adapted for cap-
turing prey, the labium being wholly relied upon for that purpose.
The coxae are nearly sjiherical and slightlv compressed. The trochan-
ter consists of two segments. The proximal segment is narrow and

421

capable of being telescoped into the coxa. Tlie second segment is
longer, and its ventral length is greater than its dorsal. The femora
are subequal in length, the posterior being slightly longer, especially
in Argia and the Lestinae. The tibiae are also nearly equal in length
and are slender and cylindrical. The tarsi have three segments. The
proximal segment is short and is extended below the second segment
so that its ventral length is greater than its dorsal. The second segment
is usually about twice the length of the proximal but, like the proximal
one, is extended on the ventral side. The third segment is longer
than either of the two proximal ones, being in some cases nearly
twice as long as the second and four times as long as the first. At the
distal end of the third segment, on the ventral surface, there can be
found a small sclerite which probably represents an extra tarsal seg-
ment and is known as the pretarsus (Fig. 19, pta). It is drawn out
distally into a slender process. The tarsal claws vary to some extent
in length but are always sharply pointed and somewhat swollen at base.
They are never bifid at the tip as in the adult. The legs of the nymphs
never bear the long spines characteristic of the adult but, instead, there
are weak setae or short spinules which collect particles of dirt and
enable the insect to hide with ease. In the Agrioninae, there are to
be found short, minute, three-pointed scales at the ends of the tibiae,
the function of which is obscure (Fig. 19). The tarsi in all species
possess two to four rows of short setae on the ventral surface. The
markings of the legs vary with the genus, but consist largely of black
rings on the femora and tibiae. In Agrion, nearly the whole of the
femur is dark except a whitish ring near the apex. The tibial bands
are mostly restricted to the proximal third and are lacking in most
species.

Wing-cases. — The wing-cases of Zygoptera appear early and at
the completion of nymphal life usually extend as far caudad as the
fifth or sixth abdominal segment (Fig. 25, wc). The tracheation of
the pad is often obscure but the veins are sometimes plain enough to be
of value in identification. Ontogenetic studies of the wings can only
be made at intervals during the growth of the nymph, the obscure
nature of the contents of the pad making such study difficult during the
greater part of the time. In no case do we find the radial sector actu-
ally crossing over the media as in the Anisoptera, and, as pointed out
by Needham ('03)' the subnodal cross-vein formed by the proximal
end of the radial sector has been reduced and lost. The distal portion,
however, may be seen in Lestes, but not usually in other species, and
branches from the second media a short distance from its separation
from the first media (Fig. 14, Rs).

422 '

Abdomen. — The alxlomen is always composed of ten complete
body-rings. The eleventl: segment, seen best in Lestes, is represented
by the small basal processes (Figs. 5, 18; An) to which the caudal
gills are attached. The twelfth segment, supposed to be present in
the minute sclerites liounding the anus, is apparently wanting or indis-
tinct. Each body-ring is without sutures but is roughly divided by
the lateral carinac into sternal and tergal areas. In the Coeuagrionidae,
the lateral carinae of the first eight segments are known as lateral
keels (Fig. 25, Ik). In Lestes, the caudal extremity of each keel is
sometimes drawn out into short setae and is setose or hairy along the
margins. Marginal setae are also present in the Coenagrionidae but
the heavy caudal setae are wanting.

Sexual Appendages. — It is claimed that the sexual appendages of
the nymphs (Balfour-Browne, '09) can not be seen and differentiated
until about the time of the seventh molt. From personal observations,
however, it would seem that the appendages appear much earlier than
this, and pogsiblv as early as the fourth molt. The male genital ap-
pendages are located on the ninth abdominal sternum and consist of
a simple pair of short, sharp, conical styli, near the ventro-meson.
There is also an indication of the location of the male copulatory
organs on the ventral surface of the second and third sterna (Fig.
24, ag), though nothing definite is formed there until the adult
emerges. The ovipositor of the female is composed of six processes
developing from the eighth and ninth sterna (Figs. 5, 18; oce, oca).
Four of these are similar in appearance, being slender, curved, blunt
projections extending commonly beyond the end of the ninth segment
and frequently beyond the apex of the tenth. Laterad of this double
pair of inner valves, can be found a pair of lateral styli which diflfer
from the inner valves in being pointed at the tip and much broader at
the base. The origin of the four median valves is partly from the
eighth abdominal segment and partly from the ninth, the external
ventral pair (oce) being derived from the eighth.

Caudal Gill.s-. — The caudal tracheal gills are present in the earliest
stages and are reported to have been seen in the embryo. They vary
from linear to broadly obovate in outline and from triangular to
linear in cross-section. Cuticular pigmentation, if any, is either in
transverse bands or is diffused over the entire gill. In many cases
the tracheae contain pigment, which causes them to stand out in
marked contrast to the rest of the gill. Along the margin of the gills
are rows of spines or setae, which differ in number and extent in dif-
ferent species. The lateral median ridges of the flat type of gills also
possess rows of setae, but they are difficult to observe and are of little

423

importance in classification. Two or more main tracheal trunks enter
each giil and send off branches towards the margins. The mode of
branching of the trachea is characteristic of many species, as is also
the degree of pigmentation.

A closed tracheal system has been considered possible and even
probable in the Zygoptera, but thus far no connection has been traced
by me, with the highest magnification obtainable, between the ends of
the branches of the tracheae. The normal function of the gills is one of
respiration, the minute tracheae being supposedly able to take up the
oxygen from the water and to supply the animal with a sufficient quan-
tity of the gas. Observations show, however, that complete loss of
gills does not injure the insect to any appreciable extent ; and it has
been suggested that they also have cuticular and possibly rectal respira-
tion, the latter thought to have been demonstrated in the Agrionidae.
In young nymphs there is a pulsating movement in the region of the
rectum, but cross-sections of the abdomen of Ischnura verticalis and
several species of Enallagma show that there is no connection of the
tracheal system with the alimentary tract other than a few small
branches. What seems to be a more serious impairment of life activ-
ities in the loss of the gills is the decreased power of locomotion which
the insect suffers, the gills having the same importance as the tail of a
fish. Loss of gills frequently occurs, in which case new ones are pro-
duced ; but these appear only after the insect has molted, always remain
small, and are usually abnormal in figuration and tracheation (Fig.
77a). For different types of gills see Figures 48-72, 75-77a, and 80.

Cerci. — Anal appendages corresponding to cerci are present dorso-
laterad of each lateral gill and vary in shape from tubercular to sty-
liform (Figs. 5, 18; ci).

ADULT

The adults of Odonata are distinguishable from all other orders
of insects by the type of their wing venation. The wing is character-
ized by the presence of a nodus and a stigma and a large number of
secondary cross-veins. The presence of accessory genitalia on the
second abdominal segment of the male is another unique feature. The
Zygoptera are for the most part separated from the suborder Anisop-
tera by the habit of folding their wings vertically when at rest. The
abdomen is much more slender than that of the Anisoptera, and the
wings are different in being contracted or petiolate at the base.

Head. — In general appearance the head is wide and the eyes are
very prominent, and as the head moves on a point of the microthorax
its angle of rotation is very great. The epicranial furrow is present

424

on the dorsum near the caudal margin, similar in position to that of
the nymph, and is, as a rule, indistinct unless the head is specially pre-
pared in caustic potash. The furrow begins near the caudal margin
of the dorsum, extends cephalad a short distance, forks, and extends
latero-cephalad, caudad of the ocelli, to the margins of the compound
eyes (Fig. 32, epcs). It can not be traced to the occipital foramen,
but the homology of the furrow as a whole can not be doubted. There
are three ocelli (o) cephalad of the Y, which are sometimes elevated
above the surface of the head forming the so-called ocellar area. A
furrow extends cephalad from the angle of the Y between the lateral
ocelli and forks just caudad of the median ocellus. This furrow is
present in many orders of insects, but its true homology is n(jt known.
The front includes that portion of the dorsal aspect cephalad of the
epicranial Y, between the compound eyes and cephalo-ventrad to the
fronto-clypeal suture (Fig. 32, f). Cephalad of the median ocellus
there is always a short, deep, transverse furrow which, although pres-
ent in most Odonata, must not be mistaken for a suture. The fronto-
clypeal suture does not reach the margins of the compound eyes on
either side. There is always a polished area on each side of the clypeus,
which is a portion of the gena (Fig. 32, gn). The clypeus (Fig.
32, cly) extends ventrad of the fronto-clypeal suture and is divided
into two parts bv a transverse median ridge. The dorsal part, often
dark and heavily chitinized, is the postclypeus; the ventral cne, more
weakly chitinized and often wrinkled, is the anteclypeus. The clypeo-
labral suture separates the clypeus from the sclerite ventrad of it, the
labrum (Fig. 32, liar). This sclerite is only slightly liilobed in most
species of Zygoptera, the ventral margin is directed caudad, and the
lateral margins arc convexly rounded. Laterad of the bases of the
mandibles, which lie at either side of the clypeus and labrum, there
are small semi-ovate sclerites, tiie trochantins of the mandibles (Fig.
32, tm). The fronto-genal sutures are indistinct, but are represented
by furrows extending from the dorsal articulations of the mandibles
to the antennal fossae and laterad to the compound eyes. That por-
tion of the head on the dorsum and caudad of the arms of the epi-
cranial Y, is the vertex (Fig. 32, vx), but it is not separated by a dis-
tinct suture from the occiput, which occupies the dorsal half or third
of the caudal aspect (Fig. 30, oct). The postgenae, which occupy the
ventral half of this aspect are separated from the genae by the oblique
ridge mentioned above. There is another ridge starting from the
ventral condyle of the mandibles (Fig. 30, ocr) but extending dorsad
instead of latero-dorsad. This ridge disappears near the middle of
the head.

425

Ocelli. — The location of the ocelli has already been described. They
are moderately large, elliptical, and grouped in a triangle (Fig. 32, o).

Compound Byes. — The compound eyes (Figs. 30, 32; ce) are
large and contain a large number of ommatidia. They are located
mostly on the lateral aspects of the head, but sometimes extend well
onto the dorsum.

Antennae. — The antennae (Fig. 32, ant) are usually composed of
four segments. The condyle of the scape is especially prominent.
The two terminal segments are styliform and resemble a single seg-
ment. The greatest variation in the different segments lies in the
length of the first, which ranges from hardly more than half that of
the second segment, to an equal or greater length than that. There
is also a less noticeable variation in the length of the third segment.

Labium. — The labium (Fig. 37) is the ventral movable appendage
of the head. It is a broad flat piece and covers nearly one-fourth the
entire ventral surface. The submentum (sm), the proximal sclerite, is
attached to the head and neck and comprises that part of the labium
dorsad of the hinge when the labium is at rest. Immediately cephalad
of the hinge there is a small, almost linear, transverse area, the mentum
(me). Beyond this there is a large subtriangular piece with a deep me-
dian, distal cleft and a suture-like furrow extending to the proximal
end. This piece is the median lobe (ml) and represents fused glossae
and paraglossae. On each side of this median lobe there are heavy
blade-like lobes, the labial palpi, which connect with the proximal part
of the median lobe. The fixed proximal segment is the palpiger (pi),
the large movable distal portion is the pro.ximal segment of the palpus,
and the short blunt movable appendage borne by the proximal segment
is the distal segment (Ipi, Ip^). There is a long, sharp, fixed hook
mesad of the distal segment of the palpus, which in most cases is
longer than the distal segment of the palpus.

Maxillae. — The maxillae are just above the labium, one on each
side of the mouth-opening. When the labium is applied to the ventral
surface of the head, the maxillae are hidden, except the cardines and
the caudal half of the stipites. The cardo and cardella are bent at
an angle^to the stipes, but when removed from the head along with the
rest of the maxilla they are seen as two small sclerites attached to the
proximal end of the stipes, the cardo being triangular and attached to
the stipes, and the mesal side of the triangle forming the suture be-
tween cardo and cardella. The cardella (Fig. 28, cl) is a very irreg-
ular sclerite which articulates with the head capsule. Attached to the
distal border of the stipes, the quadrangular sclerite which forms the
body of the maxilla, are two appendages, the lateral more slender two-

426

segmented appendage lieing the palpus, the broader one, the fused
galea and lacinia. The palpus has a number of large setae scattered
over the surface. The galea-lacinia is more or less compressed, and
the distal margin has about six irregularly placed hooks arranged in
two rows. A marginal fringe of heavy setae extends proximad from
the hooks. In Hetaerina, if the galea-lacinia be placed on edge, there
will be seen a strong indentation between the two rows of hooks, an
indication of the fused condition of the piece. A study of Plecoptera
(Fig. 31) and Ephemerida (Morgan, '13) offers convincing reasons
for the interpretation of this piece as galea and lacinia fused, as com-
pared with a belief in the reduction of the galea, or in the fusion of
this with the palpus instead of the lacinia, or in the reduction of the
palpus. All degrees of fusion, from complete separation (Fig. 31) to
complete fusion and disappearance of the suture, may be had in series
selected from these two orders.

Mandibles (Fig. 30, md). — All of each mandible is hidden beneath
the labrum and labium except the lateral surface. The teeth are strong
and heavilv chitinizcd and the distal margins are divided into two pro-
jections, the cephalic one bearing a number of teeth, the caudal one
with a number of teeth and cutting edges arranged in the shape of a Z.

Hypo pharynx (Fig. 30, hp). — The visible portion of the hypo-
pharynx appears as a semicircular part between the tips of the max-
illae. It is much more heavily chitinized than that of the nymph, and
usually has a number of long setae attached to each lateral surface.

Pro pharynx. — The propharynx is closely applied to the interior of
the labrum and clypeus and presents no features of interest.

Microthorax (Figs. 27, 29, 36, 39). — The microthorax comprises
the neck sclerites, and is much reduced in the Zygoptera. The dorsal
and ventral sclerites (notum and sternum) and the episterna are want-
ing. The only portions remaining are the conspicuous lateral plates,
the epimera (min). In many species the epimera are much widened
on the caudAl third, and this portion is almost completely divided by
a deep cephalic indentation. The indentation separates from the maiii
part of the epimera a bell-shaped dorsal part which serves as a buffer
for the head and is to some extent freely movable. The ventral part
is slightlv larger than the dorsal buft'er, but is thrown into folds, and
the cephalic part of the ventral piece is drawn out into a long tapering
point. The tips of the epimera are fastened together by ligaments and
the head rotates upon the apices of the two together, which rest against
the body of the tentorium.

Thorax. — The thorax comprises the three body-segments caudad
of the microthorax. The first conspicuous ring is the prothorax. The

427

mesothorax and metathorax together form the division caudad of the
prothorax and are so closely united that they appear as one segment.

Prothorax (Figs. 2j, 29, 36, 39; 41, pn). — The lateral margins of
the pronotum are usually indefinite because of the disappearance of the
noto-pleural suture or because of excessive pigment. Lestes is prob-
ably the best form in which to study the prothorax on account of the
clearlv marked sutures between the sclerites. The caudal margin of
the prothoracic dorsum extends caudad as a thin blade-like projection.
There is a suture or furrow which extends cephalad from the lateral
limit of the blade-like projection and marks the lateral extent of the
pronotum (pn). Shortly cephalad of the caudal margin of the pro-
notum and parallel to it there is a deep furrow which resembles a suture
and extends from one lateral margin to the other. The area between
this fold and the caudal margin is the caudal lobe of the pronotum.
Cephalad of the lateral extremities of the caudal lobe, the suture mark-
ing the lateral boundary of the pronotum arches dorsad a little and
reaches the cephalic margin of the prothorax at the base of the mi-
croepimeron. At this point there is a second transverse fold in the
pronotum which is, however, large and more irregular than the caudal
one mentioned above. The area between it and the cephalic margin
is the cephalic lobe. Near the dorso-meson, the cephalic fold bends
caudad and there is a deep invagination here, the prophragma. Be-
tween the prophragma and the caudal lobe there is a furrow which
separates the remaining portion of the notum, not included by the
caudal and cephalic lobes, into two equal, mesal or median lobes (Figs.
36, 39; pme). The principal variations in the prothorax lie in dif-
ferences in the caudal lobe and_in the sculpturing of the dorsal sur-
faces of the mesal lobes. In Nehalennia the caudal lobe is deeply
incised and in Chromagrion (Fig. 170) this lobe is not only incised,
but there are also two flat points, projecting laterad, one on each mesal
lobe. Many other modifications also occur, most of which are sec-
ondary sexual characters.

Propleura (Figs. 36, 39). — The propleura, those areas ventrad
of the pronotum and dorsad of the coxae, are each subdivided into
three areas. Extending dorsad from the lateral procoxal articulation
(pcxp) there is a distinct suture which becomes indistinct before reach-
ing the lateral margin of the pronotum. This suture (pps), the pro-
pleural suture, is usually depressed and the depression is continuous
with that forming the cephalic fold of the pronotum. Caudad of the
propleural suture there is a large, rounded area which forms the caudo-
lateral angles of the prothorax, and ventrad of this is a small, falcate
area. Both areas constitute the proepimeron (pepn), there being no

428

real suture lictwecn the two. Cephalad of the propleural suture is a
somewhat triangular area, the proepisternuni (peps), the cephalo-
ventral angles of which are drawn out and extend ventrad in front of
the procoxae. The cephalo-ventral arms of the proepisterna are fused
with the propreepisterna. Between the dorsal triangular portion of
the preepisterna and the microepimera is a small, much-wrinkled area,
which appears to he composed of a number of scleritcs. This, how-
ever, belongs to the proepisternum.

Prostcnunn (Figs. 27, 29). — The cephalo-ventral arms of the
episterna, as described above, extend ventro-cephalad and become ap-
proximate but not quite contiguous on the ventro-meson. Caudad of
the approximated ends of the episterna there is a large shield-shaped
^•entraI sclerite the caudal margin of which is concave. This is the
fused sternum and presternum (prst). The caudo-lateral angles are
usually acute, and at the tips of these angles are found the deep in-
vaginations of the furcae (fi). Caudad of the sternum and between
the furcae is a heavily pigmented chitinizcd area, the sternellum. which
extends about as far caudad as the caudal margins of the coxae. In
some cases there is within the sternellum an elliptical or oval depressed
area much resemljling a true sclerite. This is a secondary formation.
On each side of the meson, caudad of the sternellum, is a heavily chi-
tinizcd bar which extends latero-caudad and is attached to the meso-
thorax. These bars represent the furcella (fl).

Mcsothorax and Mctathorax (Figs. 40-47). — This division of the
thorax bears the two pairs of wings and the second and third pairs
of legs. A glance at the mesothorax and metathorax of any dragon-
fly will show that the wings, instead of being borne on the mid-dorsum
of the thorax, are situated far to the rear and are inserted just above
the cephalic margin of the first abdominal segment. This change in
wing position has brought changes in the structure of the thorax as
a whole, including the reduction of primary sutures and the appear-
ance of many secondary ones, and as a result the external thoracic
skeleton of Odonata is as complex as that of the highly specialized
Hymenoptera and Diptera.

Mcsnotnni (Figs. 41, 44, 46, 47). — As hAs been mentioned in
tliC nvmphal description, the mesepisterna are approximate on the
dorso-meson. In the adult the two have united and fused, a single
suture, being left, extending from near the caudal margin of the pro-
notum to the wing bases. In some cases this suture is slightly elevated,
forming a carina (dc), but it is often flattened at the point of fusion
of the two pieces and the suture nearly obliterated. Cephalad of the
dorsal carina there is a small somewhat rhomboidal area, the prescutum

429

(mscl). There is a deep invagination near its cephalic angle but no
invaginations of the internal skeleton occur here. Caudad of the
caudal extremity of the dorsal carina and adjacent to the wing bases
there are two small, frequently subcrescentic pieces which are approxi-
mate on the mesal margins and extend well towards the first lateral
suture of the thorax. These are the combined mesepisternal paraptera
(p). Caudad of the mesepisternal paraptera, but on a distinctly lower
level and between the first pair of wings, is the second portion of the
mesonotum, which consists of a number of irregular hummocks sep-
arated by depressions, sutures, and ridges. Just caudad of the parap-
tera on the dorso-meson there is a very deep invagination of the mesa-
phragma, which is situated near the cephalic margin of the mesoscutum.
(msec). At this point the mesoscutum is narrow, but widens soon
after extending caudad a short distance and forms a process, the
anterior wing-process. From this point the margin extends caudad
and forms a similar process, the posterior wing-process. The caudal
boundarv of the scutum is formed by a heavy chitinous line, bent
caudad and extending from side to side between the caudal wing-
processes. ' From the caudal wing-processes the lateral margins of the
mesonotum, now the scutellum, extend caudad to the point of entrance
of the spring-vein (Figs. 46, 47; spn) which always marks the caudal
iiiargin of this sclerite. The central portion of the scutellum is ele-
vated to form a sort of knob, which is heavily chitinized. The portions
on either side of this are depressed and as a rule less heavily chitinized
than the elevated portion. The area caudad of the spring-vein is the
postscutellum (mopl), the latter extending as far as the deep fold
v^'hich forms the cephalic border of the metaprescutum.

Mctanotuui (Figs. 46, 47). — The metaprescutum (psct) is a nar-
row, transverse, heavily chitinized sclerite forming the cephalic mar-
gin of the metanotum. It is in great part covered by the membranous
postscutellum of the mesonotum but can usually be seen through the
latter. On the lateral angles, there are slight ental projections. Caudad
of the transverse prescutum, there are four large areas composing
the scutum (mtsc) and three deep longitudinal folds which mark ofif
the fou,r areas, but no primary sutures. There is also a somewhat
irregular area caudad of the four larger ones. The caudal margin of
the scutum is depressed laterad, and the latero-caudal angles project
and form the anterior wing-processes. The metascutellum (masl)
is similar to the mesoscutellum (mosl), the caudal boundary being
marked by a spring-vein (spn) and the sclerite, as in the former case,
having a raised central portion and depressed lateral ones. The postscu-

430

tolliim comprises the area caudad of the spring-vein and cephalad of
the first aljdominal segment.

Mcsotlwracic Spiracles and Mesostignwl Plates (Figs, ^i, 43-45.
212-216). — The mesothoracic spiracles of Zygoptcra are hirge and
have exceedingly large tracheal trunks connected with them. As in
tiie nymph, the spiracles have migrated dorsad and are located near
the lateral angles of the mesoprescutum and beneath the projecting
caudal margins of the pronotum. Adjacent to the sjjiracle on two
sides, are two heavy plates, the ventral one of which i.s highly polished
(Fig. 45, mstv), allowing the prothorax to play upon it to a certain
extent. The caudal plates (mstg) are usually triangular and assume
a variety of forms in different species. Botla of these plates belong
to the peritreme of the sjiiracle. The caudal plate has Ijeen assumed
by Snodgrass ('09) to be homologous with the depressed area in
Anisoptera which extends across the dorsum just caudad of the pro-
notum. A study of the nymphs of Anisuptera proves conclusively
that such is not the case, for in the nymph the depressed area may be
deserved to develop from the mesepisternum. Another possibility in
the derivation of the caudal plates is that they have arisen from the
mesoprescutum, and the wide depressed area of Anisoptera may also
have had the same origin. This is strongly supported by the apparent
disappearance of all traces of the prescutum in the adults. There is,
however, a remnant of the prescutum in the adults of Gomphus where
tlie area occupied by the prescutum lies entirely within the transverse
depression and the true stigmal plate is closely applied to the stigma.
From this it seems that the depressed area of Anisoptera can not be
homologous with the spiracular plates of the Zygoptera, but that it
must have developed simply from a depression of the mesepisterna.

Use has been made of the caudal stigmal plates in the classification,
especially in the case of the females, of the genus Argia. Kennedy
('02a) and Calvert (Calvert and Hagen, '02 :i03) were the first to call
attention to these plates in America, but their use was hinted at as long
ago as 1865 by de Selys ('65: 381). In the genus Argia the caudo-
mesal angles are the variable parts of the sclerites. There is considerable
difference also in the plates of females of the Coenagrionidae, and
individuals of this sex may often be separated by the use of this
character. In the Lestinae and Agrionidae, the character seems to be
without value, which fact makes the members of the genus Lestes, at
least, one of the most difficult of all genera of Zygoptera to determine.

Mcsoplcura (Figs. 43, 45). — The mesopleura are closely united
to the metapleura in most Zygoptera and the interpleural suture has
been lost in many cases. This suture can be traced for its full length

431

only in the family Agrionidae (Fig. 45, insu), in which it extends
from a point between the mesocoxae and metacoxae, caudo-dorsad to
the caudal margin of the first pair of wings.

Mcxcpistcnia (Figs. 43, 45). — The mesopleural suture, dividing
the mesopleura into episterna and epimera, may be traced by locating
the lateral articulation of the mesocoxae (Fig. 40, mcp) and the
mesopleural wing-process (wp) — a heavily chitinized process extend-
ing from the caudo-dorsal margin of the thorax into the membrane
at the base of the first pair of wings. The suture will be found to ex-
tend cephalad, beginning at the wing-process, parallel to the dorsal
carina, as far as the cephalic third of the mesothorax, where it appar-
ently forks, and sends one branch cephalad and the other ventrad to
the coxal process (mcp). The horizontal fork is a secondary suture
and separates the small sclerite above the coxae, the infraepisternum
(ieps), from the rather large oblong sclerite, the supraepisternum
(seps).

Mcscpimcra (Figs. 43, 45). — The mesepimera lie caudo-ventrad
of the mesopleural sutures. In the Coenagrionidae they are fused
with the metepisterna and the interpleural suture is obsolete except
near the wing bases. In the Agrionidae the interpleural suture is dis-
tinct throughcnit its course, and the metepimera are then elongate
sclerites with the dorso-cephalic angles considerably rounded.

Mctaplcura. — The key to the metapleura is the metapleural suture,
wTiich may be traced in a similar manner to the mesopleural suture.
This may be done by finding the metacoxal articulation and the meta-
pleural wing-process (wp), situated at the base of the second pair of
wings, and following the suture between the two points.

Mctcpistcnia (Figs. 43, 45). — The metepisterna are those portions
of the metapleura cephalad and dorsad of the metapleural suture (Fig.
45, mtsu). Like the mesepisterna they are divided into two separate
sclerites, a small one dorsad of and adjacent to the coxae, the metin-
fraepisternum, and a larger, elongate one dorsad of the metinfraepi-
sternum and extending from the ceplialic margin of the latter caudo-
dorsad to the bases of the wings — the metasupraepisternum (seps).
The latter is narrowed to about half its width abov.e the infraepisternum
and usually bears the metathoracic spiracles (Fig. 43, mtsl) within
the constricted portion. In many species there is a secondary suture
extending between the spiracle and the metapleural suture (Fig. 45).

Metepimera (Figs. 43, 45).— Caudo-ventrad of the metapleural
suture is the metepimeron. The metepimera are contiguous on the
ventro-meson. In the Agrionidae the boundaries of the sclerite, be-
ginning with the metacoxal process (mtcp), may be indicated as fol-

432

lows: — The margin extends vcntro-niesad (Fig. 40), meeting its fel-
low from tlie opposite side on tlic meson, then extends caudad half-
way from the coxae to the first abdominal segment, bends laterad to
the elevated lateral carina, caudad again to the abdomen, then dorsad
(Fig. 45) along the wing bases to the metapleural suture (mtsu),
which forms the dorso-ce])halic border of the sclerite. At the caudo-
ventral angles of the epimera there is a small triangular sclerite which
if apparently cut off from the main portion of the epimeron. The
primary suture follows the ventral margin of the deep fold which
occurs at this pf)int. The latero-ventral carina does not follow the
ventral suture of the epimera all the way from the abdomen to the
coxae, but, instead, follows a more direct line along the ventro-lateral
margins of the thorax and diverges from the suture half-way from
the abdomen to the coxae (Fig. 40). In the Coenagrionidae the
sutures marking the ventral borders of the epimera are less distinct
and do not follow cjuite the same course (Fig. 42).

Mcsosternum and Mctastcrniini. — The approximation of the coxae
in the adidts of Zygoptera has brought about profound changes in the
mesosterna and metasterna.

Mcsostcnitiin (Figs. 40, 42; mst). — The key to the mesosternum
lies in the invaginations of the furca (mfi) which mark the caudal
limits of the sternum. In the Agrionidae the elevated parts of the
sternum and sternellum form a distinct hour-glass figure with the furca
on either side of the contracted portion. The margins of the sclerites
are, however, parallel to the elevated portions, but are somewhat de-
pressed. If the cephalo-latcral angles of the sternum are followed
to the sides of the t]if)ra.\ they will be found to extend nearly as far
dorsad as the dorsal margins of the mesinfraepisterna. The cephalo-
lateral arms are exjianded dorsad, and there are apparently several
sclerites represented in the upper portions. possil)ly tlie remnants of
the mesopresternum (Figs. 43. 45; pst). Along the lateral margins
of the sternum cephalad of the furcae there are obscure invaginations
which represent the prefurcae (mpf). These are difficult to see from
tlie exterior unless the cuticle is cleared.

McsostcrncUttni (Figs. 40, 42 ; mstm). — The mesosternellum is
similar in shape to the sternum except that the caudal margin is convex
and heavilv chitinized in some groups, notably the Agrionidae. The
chitinized portions represent furcellae. From the caudal margin of
the mesosternellum there extends a short, heavy, chitinous projection
v\hich sinks into the metathorax, and is lost from sight beneath the
metasternella. This is a part of the metasternum (Figs. 40, 42).

433

Mctastcnium (Figs. 40, 42). — This sclerite is even more pro-
foundly modified and distorted than the mesosternum. The meta-
coxae are ahnost contiguous and the muscles attached to the meta-
sternum along the meson have drawn it well into the interior. The
metafurcae can only be seen upon dissection of the thorax, and are
to be found closely approximated along the ventro-meson. The pre-
furcae (mtpf) are a short distance cephalad of the furcae (mtfi).
The presternum and sternum are fused, and the cephalo-lateral arms
extend around the cephalic margins of the coxae and unite with the
metinfraepisterna. The sternellum is represented in each sclerite
niesad of the caudal half of the metacoxae, the caudal boundary being
marked by two nearly contiguous chitinized spots on the meson (Figs.
40,42). '

Intersternum (Figs. 40, 42; ints). — The closing together of the
metepimera has apparently resulted in the isolation of a portion of the
sternum, near the abdomen. Comparisons with the thorax of
Orthoptera and other orders show that this may be a portion of the
abdomen, but in this case it is probably the cuticular membrane de-
veloped between the abdomen and thorax. The possibility that this
sclerite represents an extra abdominal segment has alreadv been dis-
cussed under the description of the nymphal thora.x. The name inter-
sternum has been applied to this area.

Postcoxal Area. — The area on the thoracic venter between the
lateral carinae, caudad of the metaco.xae and cephalad of the first ab-
dominal sternum, is the postcoxal area.

Legs. — The legs are long and comparatively slender, and have
long setae arranged regularly in rows (Fig. 35). They are not adapted
for walking or running.

Coxae (Fig. 35, ex). — The coxae are large and globular, and there
are prominent ridges on the lateral surfaces of the procoxae and the
caudo-lateral surfaces of the mesocoxae and metacoxae.

Trochanters (Fig. 35, tr). — The trochanters are much'smaller than
tlie coxae and are divided into two short pieces in all families. The
ventral length of both portions is much greater than the dorsal.

Femora (Fig. 35, fe). — The femora are long and cylindrical and
without carinae except in a few genera. The ventral surface is pro-
vided with two rows of long black setae (fs), varying in number from
three or four on the fore tibiae to as many as sixteen or seventeen on
the hind tibiae.

Tibiae (Fig. 35, ti). — The tibiae are likewise long and slender and
have a double row of setae on the ventral surface. In the fore tibiae
of most species the setae of the cephalo-ventral row are conspicuously

434

flattened. The comb (tic) formed by these closely placed setae is
probably used for cleansing the mouth-parts or the antennae. There
is a great deal of variation in the length of the tibial setae and also in
the number present in different subfamilies.

Tarsi. — The tarsi are always composed of three segments, the seg-
ments increasing in length from the proximal to the distal end (Fig.
35, ta). They are also provided with a double row of setae beneath,
but these are never as long as the tibial or femoral setae.

Prctarsiis. — The pretarsus (Fig. 19, pta) is beyond the end of the
third tarsal segment and consists of a small sliield-shaped piece on the
ventral surface just beneath the bases of the claws. It extends back
into the third segment, and in order to be seen best the claws should be
pulled outward a little. There is also a small projection attached to the
tip of this sclerite. but this is not homologous with the empodium of
other insects. The ventral apical margin of the last segment of the
tarsus is deeply emarginate on each side of the pretarsus.

Claws. — The claws are long and slender and the tips are always
notched or bifid (Fig. 35, cw). The rays are seldom equal in length,
and in some species the notch is far proximad of the apex.

Wings (Figs. 73, 74, 78, 81-90). — All Zygoptera have four sim-
ilar membranous wings. In respect to venation and shape, the genus
Hetaerina may be said to have the most primitive wing of any zygop-
teron found in Illinois (Figs. 74, 78). The position and course of
the veins in the wings of this genus are as follows : — The costa. first
longitudinal vein, forms the cephalic margin of the wing. The sub-
costa, second longitudinal vein, extends half the length of the wing
from the base and ends abruptly in a short fork which marks an in-
dentation in the margin. The two forks of the tip of this vein are
in line witli a lieavy cross-vein caudad of it. and the Ijrace formed by
the alignment <if the cross-vein and tlie sul)Costal forks is known as the
nodus. The third longitudinal vein extends from base to apex of the
wing and is' composed of fused radius (R) and media (M) as far
distad as the nodus and first radius (R,) plus the second subcosta
from nodus to apex. There are a number oL cross-veins extending
between costa and subcosta from the base of the wing to the nodus —
the antenodal cross-veins. Between costa and radius, distad of the
nodus and jn-dximad of tlie stigma — the hea\ilv chitinized spot near
the ape.x of the wing — are the postnodal cross-veins. The remaining
branches of the radius are united, forming the radial sector (Rs), and
separate from tlie main trunk at the nodus. The course of the radial
sector is difficult td follow because of its crossing one or two of the
median veins. In Hetaerina the radial sector branches from the radius

435

at the nodus, crosses the first median vein, the first vein caudad of it, at
the point where the second median vein separates from the first, fol-
lows the second vein for a short but indefinite distance, being fused
M'ith it, and then crosses over to the longitudinal vein caudad of the
second media, and continues its course to the margin of the wing (Fig.
74). The point of separation of the radial sector from the second
media is not evident, there being no oblique cross-vein as in the Ani-
soptera. The vein uniting the caudal end of the cross-vein over which
the radial sector crosses, to the main radio-medial trunk is known as
the bridge (seen in Lestes and Ischnura, Figs. 81, 85; br), and is
secondary in origin. In Hetaerina the trachea of the bridge is fully
as strongly developed in the nymph as any other of the main tracheal
trunks. Such a feature would perhaps throw some doubt on the actual
formation of the bridge in this suborder were it not for the strong
comparative evidence present in the Anisoptera. The bridge reaches
R-plus-M about half-way between the nodus and the base of the wing.
About one-third of the distance from the base to the nodus is a strong,
oblique cross-vein, the arculus (Figs. 81, 85; arc), from the middle
of which two longitudinal veins arise. These veins are the third and
fourth median veins (Mg and M4), respectively, the cephalic one being
Mg. A short distance from the arculus there is another heavy cross-
vein connecting M4 with the longitudinal vein caudad of it. The cross-
vein probably represents the medio-cubital cross-vein. The four-sided
area enclosed by this vein, the portions of M4 and the longitudinal vein
caudad of it (the cubitus) and distad of the arculus, forms what is
known as the quadrangle (qd), and corresponds to the cell first M4.
The cubitus extends from the base of the wing to the distal side of the
quadrangle, where it forks and sends out two longitudinal branches
caudo-laterad to the margin of the wing. The forks are Cu, and Cu,,
or first and second cubitus. The anal vein (A) consists of a single
heavy trunk extending from the base of the wing and apparently con-
necting with the cubitus at the point where the latter forks. The dif-
ferent anal veins can not be traced because of numerous secondary
cross-veins.

Many variations occur in the above wing-venation, but instead of
a discussion of each in detail the reader is referred to figures 73 and
81-90 which show the types of venation occurring in the remaining
genera of Zygoptera found in Illinois.

Abdomen (Figs. 91-100, 104). — The abdomen of all Zygoptera is
cylindrical and composed of ten complete segments. In all of the seg-
ments the sterna are much reduced and hidden by the overlapping
terga. The pleura are still more reduced, so that no portion of them

436

can be seen in the normal insect. If the body be softened and the
lateral margin of the terga extended, tiie pleura appear as membrane
between the margins of the terga and the sterna. In this membrane,
near the cephalic-lateral margin of the first eight segments, the ab-
dominal spiracles are found. The terga of all the segments are always
large, are bent around from the dorsum onto the lateral aspect of the
abdomen, and usually extend slightly onto the venter. A single
tergum, then, has a dorsum and pleuron of its own. The terga are
usually transversely rugose on the dorsum, and the lateral margins are
always paler than the dorsum, and finely pilose. The apical margins of
all except the last segment have elevated subapical chitinous rings wliich
are frequently provided, especially in the terminal segments, with a
number of short, heavy setae. The apical margin of the tenth segment
may bear a long spine at the apex ( Fig. i lo) , or the apical margin may
have a long, subapical, lilunt process (Figs. i66, 167), or it may be
simply emarginate. The sterna are narrow^ transversely, with the
exception of the first two and the last two, and are more or less hidden
by the margins of the terga. The first sternum (Figs. 40, 42) is
usually subtrapezoidal with tlie cephalic margin concave. The second
sternum of the male is developed into an accessory copulatory appara-
tus which will be described later. In the female this sternum is sim-
ilar to sterna three to eight and consists of an oblong plate of chitin,
slightly wider cephalad, and liaving small ental projections at the cepli-
alo-lateral angles. The eighth sternum of the female is divided into
three sclerites (Figs. 109, 116), a single large proximal one and two
small, sometimes obsolete, ones which are intimately connected with
the first pair of gonapophyses. The ninth sternum (Figs. 109, 116)
is greatly reduced in the female, being represented by narrow sclerites
along the margins of the tergum extending from the proximal end to
about the distal third or half of the segment. The ninth sternum of
the male bears the genital opening, and on each side of this, and cov-
ering it, there is a more or less oval plate. These plates are known
as the parameres (pa, Figs. 118, 121, 147, 165, 171, 172, 183). The
tenth sternum is fused with the tergimi on the lateral aspect.

Abdoiiiiiuil Apl^cndagcs. — This term includes the accessory gen-
italia and anal appendages of the male, and the ovipositor of the
female.

Accessory Genitalia (Figs. 33, 97, 98, loi. 105, 107, 108, 120,
122). — The accessory genitalia of the male are derived from the sec-
ond and third sterna, anil a portion sometimes from the second tergum.
The sperm duct opens in the ninth sternum and spermatozoa are trans-
ferred to the accessory pouch or vesicle by doubling the abdomen upon

437

itself. The sternum of the second segment forms two heavily chi-
tinized hamules (Fig. 33, hm) which serve as covering plates. The
membranes immediately below these form a sheath for the penis (Fig.
33, ps). The latter is very heavily chitinized and is bent entad, extend-
ing to about the middle of the abdomen, and at the ental end are at-
tached heavy muscles which operate the organ. The tip of the penis
is largely membranous and flexible, and exhibits modifications which
appear to be of specific value in classification, at least in some genera.
The tip fits behind a heavy cephalic projection of the third sternum,
the seminal vesicle, when not in use (Fig. 33, sv). Small knob-like
projections may be seen extending ventrad from the lateral margins
of the second tergum and just caudad of the hamules. These are fre-
quently concealed in the Zygoptera but are large and conspicuous in
the Anisoptera where they are known as the genital lobes (Fig. 33, gb).
The cephalic third or less of the third sternum is elevated, heavily
chitinized except at the tip, and extends some distance cephalad of the
cephalic margin of the segment. In a few Anisoptera this part is re-
ported as functioning as the penis, the parts already described for
Zygoptera being unimportant.

The variations occurring in this organ throughout the suborder are
marked and are in all cases of generic rank as diagnostic characters.
In closely related specific groups, however, it can not be relied upon,
and recourse must be had to the anal appendages.

Anal Appendages (Figs. 34, 38, 109; aas, aai). — At the caudal
extremity of the abdomen of the male there are always four appen-
dages; an upper dorsal pair, the superiors (aas), and a lower, the in-
feriors (aai). Of these, the upper is more often the longest, but it
may be reduced and shorter than the ventral pair. The anus opens
between and slightly dorsad of the bases of the mesal lobes of the
ventral pair. The dorsal pair of appendages is frequently forcipate,
and the tips are often contiguous and sometimes have between their
bases a knob-like projection.

Oz'ipositor (Figs. 109— 116). — The ovipositor of the female con-
sists of three pairs of valves or gonapophyses. The ventral, mesal
pair are slender and heavily chitinized, and are transversely ridged at
the tip and usually provided with a saw-tooth edge. The cephalic pair
of gonapophyses (oce) is derived from the eighth segment; the median
pair (not shown in the figures) and the broad caudal pair (oca) from
the ninth segment. The caudal pair of gonapophyses differ much in
shape from the cephalic and median pairs. They are very broad at the
base, somewhat contracted at the apex, and bear short, chitinized,
curved subapical rods, the prostyles (prs). The ventral margins of

438

the caudal valves are always serrate.

Variations in the ovipositor of the female are seemingly of little
importance in classification although there is enough difference in the
apical sternites (sti.s) of the eighth segment alone to facilitate the sep-
aration of genera.

Life History and H.a.bits

The metamorphosis of all Odonata is incomplete and the life his-
tory relates to the egg, nymph, and adult.

EGG

The eggs of Zygoptera are elongate and ovoidal, their length being
much greater than their transverse diameter. In length they average
about one millimeter; in diameter usually about one-fourth of this.
They are inserted cither above or below the surface of the water in
the stems of plants. Lestes and related genera insert the eggs con-
siderably above the level of the water, and several instances are re-
corded in which the plants suffer from excessive oviposition. Most
of the Coenagrioninae oviposit beneath the water upon the submerged
parts of plants. To accomplish this, the female with the male clinging
to her alights on a projecting part of a plant and backs down into the
water dragging tlie male with her. She often goes so far beneath the
surface that I)oth are completely suljmcrged. Kellicott ('99:24)
observed the females of Argia moesta puirida descend into the water
in this fashion; and I have frequently .seen EiMllagiiia sigiiatiDii de-
scend into the water to oviposit and, less frequently, Jschmtra z'crticalis
and Enallagiiia aiitciinatuni. It is probable that many more of the
subfamily Coenagrioninae enter the water to find a suitable place for
oviposition. The egg-laying habits of the Agrionidae have not been
extensively studied; but Kennedy ('15:339) reports that Agrioii
acquabilc variety yakuna deposits the eggs beneath the surface of the
w-ater upon willow roots, and is unaccompanied by the male. Need-
ham also says that Agrion tiuiciilatum oviposits just beneath the sur-
face of the water, but Wesenberg-Lund ('13) ol)ser\cd a luirojiean
species depositing eggs above the water. In all cases tlic female was
unaccompanied by the male.

The number of eggs laid by a single female has been but partially
investigated, owing to the great tlillicultv of intlucing the female to lay
in captivity. A number of adults were dissected with a view to discov-
ering the egg-laying capacities of the group. Several reared specimens
whicii had no chance to deposit eggs were found to contain as many

439

as looo ova but only 60 or 70 of them were of normal size and con-
sidered mature. Another female, Ischuura rcrticalis, contained 203
mature ova, while a third teneral female of Bnallagnia hageni con-
tained 290 mature ova. Calvert ('93) says that the average dragon-
fly probably lays between two and three hundred eggs, and this state-
ment seems to coincide with that above.

The length of time spent in the egg stage is also imperfectly
known. Lucas ('00: 18) reports that Sympetrum striolatum spends a
month in this stage. Balfour-Browne ('09:256) says that eggs of
Ischuura clcgaiis and Bnallagnia pulchclluni, laid at the beginning of
August at East Norfolk, England, required from four to five weeks
to develop. The temperature relations are not mentioned, but it is
probable that this period varies to some extent. Needham ('03) calls
attention to the fact that the eggs of Lestes, which are laid above
water late in July, develop to a certain point, apparently ready to hatch,
and await submergence before eclosion. The water does not reach
them until late in fall ; and this means that at least several months are
spent in the egg stage. Brandt ('69) reported the development of
Agrion (Caloptcryx) virgo in three weeks during a hot summer.

In the final stages of embryonic development the head is directed
towards the small end of the egg. This end is always nearest the
cuticle of the plant, and the nymph consequently emerges head first.

NYMPH

Grozvth. — Immediately after hatching, the nymph is helpless and
unable to move about actively. In this condition it is known as the
pronymph (Balfour-Browne, '09:258). A few minutes afterward the
skin of the pronymph splits and the true nymph escapes. During the
second nymphal stage the nymph is a minute insect, hardly longer than
the egg from which it hatched. The antennal segments are three
and there are no wings or sexual appendages. Erom this stage the
nymph grows and molts at intervals, the time between molts depending
largely upon the temperature and the amount of food which it is able
to capture. The antennae increase in number of segments until six
are present, in which condition they remain until the last nymphal
stage, when there are seven. The wings appear as ridges during the
fourth stage, but the sexual appendages do not appear until the seventh
stage, according to Balfour-Browne ('09). This seems to be contra-
dicted by the rather frequent observance of nymphs without wing-cases
and fairly well-developed appendages. There is great variation in the
time between molts, due primarily to temperature. It often happens

440

that when nymphs are brouglit into the warm laboratory they molt
within a few days. Balfour-Browne found surprising differences in
the time between molts in nymphs kept at constant temperatures, so
that it would seem probable that other factors enter into the problem
besides temperature. He was able, however, to reduce the length of
the stages by raising the temperature, and found that in some cases
these lasted, in low temperatures, for 150 days, while in others they
lasted only five days at higher temperatures. The number of molts
varies from ten to fifteen in the Coenagrionidae, and the length of the
nymphal life may range from 229-624 days (Balfour-Browne, '09).

Habitat. — In nature, the nymphs are most often found hiding
among the weeds and rubbish along the margins of lakes, ponds,
and streams. A few have been taken under rocks in swift currents,
among them Argia piitrida- (Needham, '03) and Argia tibialis. The
Agrionidae frequent the swifter currents, and seem to prefer these
situations to any others. They are never found in stagnant ponds.
Nymphs of Lestes, on the other hand, do not occur except in stagnant
woodland pools, and are never taken along the banks of streams unless
a stagnant condition is present. They prefer the shade, and hide
among the broad-leaved types of small water-weeds, being rarely found
among the narrow-leaved rushes and saw-grass. Riley ('12) says
that the nymphs of Zygoptera react negatively to light from a pro-
jection lantern but that such a reaction is often inhibited by the habit
of clinging to objects. He was unable, however, to obtain similar
reactions to moderatelv strong daylight. Reactions to heat have not
been studied, but the nymphs are able to withstand temperatures near
the freezing-point and may be collected during the winter from be-
neath the ice. They readily succumb when the temperature of the
water rises much above /0°F., but flourish well at 66.2°F. or I9''C.
(Balfour-Browne, '09). Lestes is particularly sensitive to high tem-
peratures, and when in captivity considerable care must be taken to
keep the temperature low enough for them.

Food. — The food of the nymphs consists almost entirely of Crus-
tacea, the larvae of nematocerous Diptera, such as mosquitoes and
chironomids, and ephemerids. Very young nymphs have been known
to thrive on Paramecium and other Protozoa. Of a large number of
Lestes which were dissected, nearly all contained Daphnia and Cyclops,
while the coenagrionines dissected contained many heads of chirono-
mids and only occasionally small Crustacea. However, a single small
Ischnura verticalis nymph contained eight specimens of Daphnia, and
it seems highly probable that other insects are also taken when the
normal food supply is scarce. Diatoms and other minute organisms

441

are frequently found in the alirrientary tract, but this is due to the fact
that other insects have been eaten which feed upon these organisms.
The following is a list of the kinds of food known to be eaten by
zygopterous nymphs.

Protozoa Paramecium.

Crustacea

Copepoda . . . Cyclops.
Anemopoda . . . Daphnia.

Arthropoda

Arachnida . . . Hydrachnidae (rare).

( Diptera — Chironomidae, Culicidae.
Insecta ....■< Odonata — Zygoptera.

( Ephemerida — Ephemeridae.

Vertebrata Very young fish.

Color Adaptations. — In almost any collection of live zygopterous
nymphs, there will be found brown and green individuals of the same
species. When collected from localities with abundant green vegeta-
tion, nearly all the nymphs will be green ; when taken from situations
where little green vegetation occurs, the nymphs are brown or dark
in color. Furthermore, as has been observed in rearing specimens,
green nymphs placed in a jar without green plants become brown after
a few molts, and thus seem to be able to adapt themselves to the color
of the surroundings. The color of the nymph, contrary to what might
be expected, seems to have no influence upon the color of the adult.

Enemies. — The nymphs of Zygoptera are preyed upon by a number
of enemies, the most formidable of which are fishes. Forbes ('88)
reported that odonate nymphs formed ten to thirteen per cent, of the
food of Perca flavescens — the common perch, Aphredoderiis sayanns
— the pirate perch, and Ponio.xis annularis, the crappie ;and twenty-five
per cent, of the food of the grass pickerel, Eso.r vermiadatiis. Riley
('12) says that Lepomis gibbosus, a common sunfish, and the yellow
perch. Perca flaz'csccns, commonly feed upon agrionid (coenagrionid)
nymphs.

Among the predaceous aquatic Hemiptera, the genera Ranatra,
Belostoma, and Notonecta, and probably others, feed upon the nymphs.

A mite, Arrhcmirus sp., is a common external parasite of the
nymph. At the time of emergence of the adult, the mite migrates from

442

the n^'iiiph to the adult and is carried about by tiie latter until it is
nearly mature, when it escapes again into tiie water for the final stage.
Another mite has been reported to feed upon the eggs of Anisoptera,
but this statement has not been verified for the Zygoptera. Needham
('03) says that a large number of hymenopterous parasites prey on
the eggs of Lestes, left exposed above the water-line, and he reared
tlie following species: Brachista pallida Ashm., Ccntrobia odoiiatae
Ashm., and Polyncma nccdhanii Ashm. Brandt ('69) also reports
rearing Polynema ovulonini from the eggs of Agrion (Calopteryx)
and says that as many as fifty per cent, of the eggs were sometimes
destroyed by this parasite.

A fungus belonging to the Saprolegniales frequently attacks the
nymphs, especially if enfeebled from any cause. Sometimes it be-
comes \er\ tlifficult to rear specimens, and if the rearing-jars become
infected nothing short of thorough sterilization will be of any avail.
This fungus is related to the one attacking fish and causing great
damage in hatcheries. It is also known to attack the larvae of Coryd-
alis.

Emergence of Adult. — When the nymph has molted a stated
number of times, somewhere between ten and fourteen, and has be-
come full-grown, it crawls out of the water, dries its cuticle, which
soon splits along the mid-dorsum of the thorax and head, and the
adult emerges. The nymphs of Zygoptera usually seek the sunlight
to transform and emerge early in the morning, the greater number
being clear of the skin before eight o'clock. A much smaller nvun-
ber have been seen to emerge after six o'clock in the evening or late
in the afternoon, but very few, if any, emerge during the heat of the
day. The emergence follows a more or less definite schedule. When
first out of the nymphal skin, the parts of the body are no larger than
the parts of the foregoing nymph, and the insect is yellowish green
in color. Great changes soon begin, including an elongation of the
abdomen and wings as well as enlargement of other parts, and within
an hour the insect is ready to take flight. At this time it may show
mature coloration or the color may still be incompletely develojied,
and in this condition the adult is known as teneral. The teneral state
may last for several days or longer, depending somewhat upon the
amount of sunlight to which the insect is subjected, or there may be
no further change after the power of flight is attained. Euallagnm
exsidans, E. gcmwatutii, and the male of Ischmira verticalis are ex-
amples of species which apparently have no teneral state. Enallagma
conincidatuDi, and Isclniiira rcrticalis, female, are examples of spe-
cies which apparently have a long teneral period. The change from

443

teneral to full adult coloration is a phenomenon which is not well
understood. Just why the thoracic stripes of Buallagiiia signatum,
for instance, should change from a pale but distinct blue to a bright
orange in the course of development, while the stripes of the same
region in Lcstcs rcctangularis change from a dull brown to pale blue,
is impossible to explain without a more thorough knowledge of the
chemical nature of the pigments which undergo the changes.

The following observations were made upon the emergence of
Ischniira vcrticalis. The rate of development is approximately simi-
lar to that of all Coenagrionidae. The rearing-jar was kept in the
laboratory on the west side of the building and hence did not get the
early morning sun. This accounts for the late emergence of the
nymph.

9 130 A. M. The nymph crawled out upon the weeds within the
jar and seemed about ready to emerge. The nymph when removed
v.-as dissatisfied and restless and tried to get a firm hold on something
with its claws.

9:35. Body nearly dry.

9 145. The thorax suddenly splits and the insect rapidly emerges
from the skin ; color mostly light green and pale yellow ; dorsal por-
tion of the eyes dark; sides of the thorax darker.

9:50. Clear of the skin; wings 4 mm. in length, abdomen 10
mm. ; general color becoming darker ; greens becoming brown ; wings
increasing in length ; ingect restlessly moving about on the support.

9:55. Eyes plainly striped with brownish bands; abdomen 11
mm. in length, wings 4 mm. ; wings suddenly elongating near the
proximal end.

9 157. Wings 7 mm. in length.

10:00. Wings 8 mm., abdomen 12 mm. in length.

10:01. Wings 9 mm., abdomen 12 mm. in length.

10:03. Wings II mm., abdomen 12 mm.; wings pale light green,
thorax and head brownish green ; abdomen pale green at base, darker
at apex.

10:06. Wings 13 mm., abdomen 12 mm.

10:07.. Wings 15 mm., abdomen 12 mm.

10:09. Wings 15 mm., abdomen 13 mm.; abdomen suddenly
elongating at the base.

abdomen 15 mm.
abdomen 15 mm.
abdomen 16 mm.
abdomen 20 mm.
abdomen 24 mm.

10

:i4.

Wings

15

mm.

10

:i8.

Wings

15

mm.

10

:20.

Wings

15

mm.

10

:24.

Wings

16

mm.

10

:28.

Wings

16

mm.

444

10:30. Wings 16 mm., abdomen 24 mm. Thorax grayish green;
abdominal segments two to six nearly transparent; wings becoming
transparent ; stigma faint, hardh' noticeable.

10:35. No increase in length of the abdomen or wings; abdomi-
nal segments becoming dark near the sutures ; stigma of the wings
darker, now plainly noticeable; thorax olive-green; pronotum black.

10:40. First two segments of the abdomen dark green ; segments
three to six pale green, the apical segments the same as the proximal
ones; thorax becoming steadily darker; first trial of the wings; the
insect is nearly ready to fly.

10 :45. Fully able to fly, but still delicate and without full adult
coloration; no further increase in size of the abdomen or wings, but
growing steadily darker in color and indications of permanent adult
coloration becoming evident.

10:55. Stripes of the thorax very distinct, though no blue or
other bright color has appeared ; very active and using its wings fre-
quently.

12:00 M. Not yet fully colored, the two apical segments of the
abdomen beginning to show blue; the thoracic stripes of green not
fully developed.

2 :oo P. M. Postocular spots distinct ; dorsum of abdominal seg-
ments eight and nine showing signs of the blue coloration.

3 :oo. Insect fully colored and perfectly developed in every way.

ADULT

Habitat. — The adult Zygoptera are most frequently encountered
flving along tlie streams or about the lakes, ponds, or marshes in
which the nymphs aliound. Lestes is a frequenter of the thick woods
near woodkuid marshes; Hetaerina and Argia are most commonly
encountered near rapid streams, while the remainder of the Illinois
representatives of the suborder may usu;dly be found near small
lakes, ponds, or sluggish streams.

Flight. — The flight is slow and uncertain, though frequently rapid
enough to enable the insect to avoid the collector with surprising regu-
larity. The vibration of the wings is mucli slower than that of the
Anisoptera, and is more like that of a butterfly.

Mating Habits. — In summer, pairs of Zygoptera may be fre-
quentlv found flying together. The male grasps the female just be-
hind the prothorax by means of the anal appendages. The female
then doubles the body beneath the body of the male bringing the ovi-
positor in contact with the accessory genitalia of the second abdomi-

445

nal segment of the male. After fertilization of the female the two
continue to fly together and the female is refertilized at intervals
during the egg-laying period. At the time of oviposition the two
often remain together and the eggs are frequently laid while the pair
are still in copula.

The time elapsing from emergence to egg-laying is not known
with any certainty. The egg-laying period also, has been little
studied, but it is thought to last for several weeks.

Food. — Many records have been made of the destruction of mos-
quitoes by Anisoptera, but no one seems to have observed or at-
tempted to determine the feeding habits of the adults of Zygoptera.
Dissection of a number of specimens revealed the fact that the Zy-
goptera prefer small Diptera to most other food. Many remains of
nematocerous Diptera were found, as the following table will show,
but very few remains of other insects.

Name Food eaten Bate of coll. Locality

1. Hetaerina americana, g HjTiienoptera (?) Oct. — ,191.5 Muncie, 111.

2. Ischnura verticalis, g Diptera — abundant re- June 23, 1915 Havana, 111.

mains

3. Ischnura verticalis, ^ Alimentary canal empty June 23, 191.5 Havana, 111.

4. Ischnura verticalis, 5 Many .small Diptera .June 23, 1915 Havana, 111.

5. Argia apicalis, g Diptera — Nematocera June — , 1915 Clear L., Ky.

6. EnallagiiM civile, g Diptera June 18, 1915 Ilrbana, 111.

7. Lestes vigilax, ^ Diptera — Nematocera Bluifton, Ind.

8. Enallagma hageni, g Diptera — Nematocera July 18, 1915 Orono, Me.

9. Enallagma antennatum Diptera — Nematocera July 18, 1915 Ilrbana, III.

10. Ischnura verticalis Large number of butter- July 13, 1915 Lake Villa, 111.

fly scales

The most common food of the adult apparently consists of small
flies. No remnants were found which resembled mosquitoes, and the
hymenopterous insect reported is questionably identified as such. The
specimens of lepidopterous scales found in number ten were unmis-
takable, and it is, therefore, evident that other insects are sometimes
eaten besides Diptera*. They have also been reported to eat aphids.

Enemies. — The adult Zygoptera are troubled by few enemies of
any sort. Birds are perhaps the most important, but even these are
not to be considered as serious enemies. Several species of hydrach-
nid mites have been found attached to the adult, the most common of
which are species of Arrhenurus. The mites are often conspicuous
on account of their orange or reddish color, and large numbers often
attach themselves to a single individual. However, they seem to
cause the insect but little inconvenience.

*Poulton ('06) reports that both Ephemeridae and Lepidoptera are sometimes
eaten.

446

History of the Zygoptera
paleontology

The oldest records of insects which resembled Odonata are found
in the upper Carljoniferous. The wings arc the only parts which are
well preserved, but these are very different from the wings of living
Odonata. The fossil species are termed Protodonata by Handlirsch
and are thought to be connected with tiie still more ancient forms, the
Palcodictyoptera, whicii are the most primitive of all fossil insects. The
features which distinguish the Protodonata from the Palcodictyop-
tera and link them to the true Odonata include the fusion of the
longitudinal veins at tlie base of the wing; the presence of numerous
orderly arranged cross-veins; the appearance of interposed veins or
sectors between the longitudinal veins; and, finally, the approxima-
tion of the wings themselves at the base. The protodonate wing,
however, differs from that of true Odonata in the lack of stigma and
nodus and in the supposed absence of that typical feature, the cross-
ing of the radial sector over media. It is unfortunate that more of
the bodies of these interesting forms have not been preserved, for
it would I)e advantageous to know v.liat tyjjcs of head, thorax, and
abdomen they possessed.

The next remains of importance are found in the Jurassic Lias of
England and are much more closely related to living species than the
Protodonata. They are classed as Odonata anil divided into two sub-
orders, the Anisozygoptera and Archizygoptera. There is a single
living representative of the Anisozygoptera in Epiophlebia (Paleo-
phlebia) of Japan, but the Archizygoptera have no living represen-
tative, and seem to be merclv an offshoot from the Protodonata which
apparently disappeared after a short stay in geological history. The
archizygopterous wings show marked deviations from the original
type of the Protodonata, and a very near approach to some of the
zygopterous wings of today. The reduction in number of cells and
cross-veins is characteristic of both ancient and modern forms, biit
the absence of the arculus and the separation of media and radius to
the very base of the wing, distinguish the fossil species from any
living forms. Tlie Anisozygoptera have characters common to both'
Gompliitlac and Agrionidae, the oldest fossils being perhaps more
closely related to the Gomjjhidae. The wings have nodus and stigma,
and the radial sector ])lainlv crosses the median vein. The degree of
obliquity of the quatlrangle and the presence of many interposed
sectors between the longitudinal veins place them witli the Agrioni-
dae. The head and the wings resemble those of Gomjihidae in shape,

447

but the thorax and abdomen of the fossil suborder are variable and
resemble both families to some degree.

The true Zygoptera make their appearance in the Jurassic period.
The oldest of these, comprising the families Epallagidae and Stele-
opteridae, have been found in the lithographic quarries of Bavaria.
The majority of species from this source belong to the Epallagidae
and are fortunately in a good state of preservation. The wings are
not petiolate, the nodus and stigma are present, the nodus being situ-
ated near the middle of the wing and the stigma l^eing long and nar-
row. There is an oblique arculus and a more or less oblique triangle ;
the radial sector and the second median vein arise far distad of the
nodus ; and the costal field contains more than ten cross-veins proxi-
mad of the nodus. The abdomen is not greatly lengthened and the
legs are also normal in this regard. In the Steleopteridae the wing
is distinctly petiolate ; there are about five antenodal cross-veins ; and
the veins M3 and the radial sector arise proximad of the nodus. The
arculus and quadrangle are similar to those of the Agrionidae (Cal-
opterygidae)'. The family Steleopteridae is considered to be the
forerunner of the Coenagrionidae.

The Tertiary deposits furnish us with the next oldest representa-
tives of the group. True Zygoptera, Anisoptera, and a single family
of Anisozygoptera have been found in the Florissant of Colorado
and in the Tertiary deposits of Baden, Germany. Many of the species
are referable to extant genera. More than eleven genera of Zy-
goptera have been found in these strata.

The first nymphs to appear in the geological record are described
by Hagen from the Baltic amber and from the Tertiary of Rhein-
land and Baden, Germany. Many of these forms had caudal tracheal
gills and were apparently true Zygoptera. Scudder ('90) has also
figured and described a nymph from the Florissant which doubtless
belongs to the Zygoptera.

The following tabular summary gives the characters which have
been developed successively in the past, beginning with the family
Dictyoneuridae of the Paleodictyoptera from which the Protodonata
are thought to have been derived.

448

Tabular Sommabt

PAI4EODICTYOPTEEA

Dictyoneuridae

Peotodonata I

Odonata

Meganeuridae

Protagrionidao

Paralogidae

Anisozygoptera
Archizygoptera

Zygoptera
Anisoptera

Wings moderately iW i n g s moderately Wings broad or nar-
broad at base broad at base row at base

Large number of ir-
regular cells

Largo number of Reduction in the

polygonal cells

number of polyg-
onal cells

Subcosta ending in'Subcosta e n d i n g Subeosta ending at
costa beyond the about the middle middle of the
of the wing; not' wing; forked; no-
forked; no nodus I dus present

middle of the
wing; not forked;
no nodus

Radial sector not
crossing media

Radius and media
not fused at base
and no arculus
formed

Stig^ma absent

Cross-veins between A n t e n 0 dal cross-
eosta and subcosta veins much re-l
""-50 or more duced, usually

more than two in
number 1

Radial sectcr appar-
ently not crossing
media

Radial sector cross-
ing media

Radius and media Radius
fused but no arcu-
lus formed

Stigma absent

Mj arising proximad
of end of subcosta

and media
fused and arculus
frequently formed

Arculus near the
base of the wing

Stigma sometimes
present

Stigma not support-
ed by oblique
cross-veins 'or sup-
plementary sectors

Mj arising near the
subnodus, often
slightly proximad

Stigma cells numer-
ous

Wings broad or nar-
row at base.

Still greater reduc-
tion in number of
polygonal cells in
Zygoptera.

Subcosta often end-
ing proximad of
the middle;
forked ; nodus
present.

Antenodal cross-
veins often re-
duced to two in
Zygoptera; more
than two present
in Anisoptera,

Radial sector cross-
ing media.

Radius and media
fused and arculus
always formed.

Arculus further dis-
tad from the base.

Stigma only occa-
sionally absent.

Stigma supported by
oblique cross-
veins, supplemen-
tary sectors, or
both.

Mj arising at the
subnodus or con-
siderably beyond.

Stigma cells few in
Zytjoptera.

449

Tabular Summary — coniinued

Paleodictyoptera I Protodonata I Odonata

Dietyoneuridae

MegaDeuriilae

Protagrionidae

Paralogidae

Anisozygoptera
Arehizygoptera

Zygoptera
Anisoptera

No quadrangle
triangles

or No quadrangle
triangles

Three simple anal
veins present

Anal field not exten-
sively developed

Head rounded ; of
considerable size

Not known
Not known
Not known

Not known

orQuadran gle and
sometimes trian
gles present

Anal veins represent-
ed by a single
vein

Anal field not exten-
sively developed

Large numbers of
rows of cells be-
tween all longi-
tudinal veins, the
rows extending far
proximad

Not known

Not known
Not known
Not known

Not known

Anal veins repre-
sented by a single
vein

Anal field often ex-
tended, but not
braced by loop

Decided reduction in
number of rows
and a decided re-
treat distad, leav-
ing but few rows
between the prox-
imal portions

Head rounded and
of c 0 n s i derable
size

Eyes dichoptic in all
families

Labium cleft

Abdomen s 1 e n der,
occasionally swol-
len at tip; superi-
ors leaf-like or
foreipate

Inferior anal ap
pendages separate

Quadrangle always
present ; triangles
sometimes present.

Anal veins repre-
sented by a single
vein.

Anal field extensively
developed or re-
duced ; when ex-
tended often
braced by loop.

Still further reduc-
tion and retreat
distad.

Head angular; often
widened.

Eyes dichoptic or
holoptic.

Labium cleft or en-
tire.

Abdomen s 1 e n d er,
Zygoptera, or
thickened, Anisop-
tera ; s u p e r i 0 rs
leaf -like, foreipate,
or reduced to tu-
bercles.

Inferior anals fre-
quently united in
Anisoptera.

450

ONTOGENY

The various parts of the hody will now he considered with ref-
erence to their form during the different periods of development.

Head. — The compound eyes during the life of the embryo are
small and dichoptic and situated on the lateral aspect of the head.
After eclosion they become larger, are sometimes expanded dorsad,
but never become holoptic until the adult stage. The embryonic an-
tennae are composed of three segments, the second segment being
longer than all the others together, and the third segment nothing
more than a spur at the tip of the second. The increase in number
of segments takes place by division of the second, which continues to
divide until the antenna has seven segments in all. There is little, if
anv, variation in the diameter of the different segments of most
nymphal antennae, Init the proximal segments of a few are sometimes
greatly developed and much larger than any of the distal ones. In
the adult antennae, the apical segments are setiform and the number
of segments varies from four to six. The labial palpi and the median
lobe are without setae or fixed hooks. The cleft is usually obliterated
after eclosion, but remains practically luichanged in the nymphs of
some species. The labial palpi of the young nymph are soon after
eclosion provided with fixed hooks, and the median lobe is furnished
with rows of setae. The adults have no rows of labial setae, but
these are scattered promiscuously over the surface. The condition of
the mandibles and maxillae is not known for the embryonic stages,
but the nymphal condition is much simpler than that of the adult. In
this stage the mandil)Ie is not biramous except in a few cases. The
adult mandible, however, is divided into two parts, one composed of
a number of teeth and the other of several cutting edges forming a
Z when viewed from the edge. The galea-lacinia of the nymphal
maxilla is not as specialized as that of the adult, which bears a greater
number of fixed hooks and setae.

Thorax. — The thora.x of the embryo consists of three equal seg-
ments, each with a pair of appendages. Very little can be said of the
sclerites in the embryonic stages, but the segnjents of the nymph are
all about equal in size. The legs are widely separated and the in-
vaginations of all furcae are usually prominent. The suture sepa-
rating the proepimeron from the proepistcrnum is indistinct in the
earlier nymphal stages, but becomes more distinct with age. In the
mesothorax and metathorax, the interpleural suture is distinct in all
zygopterous nymphs and in the adults of the family Agrionidae. In
the Anisoptera it is indistinct in all stages. The infraepisterna and
supraepisterna are separated by furrows in the nymph, but there are
no definite sclerites formed until the adult stage. The mesonotum is

451

always divided in the nymph as in the adult, but seems to be simpler
in structure in the nymph. The mesostigmal plates of Zygoptera are
not developed until the adult stage, but the depressed area caudad of
the mesoscutum in the Anisoptera is frequently present in the
nymphal stages, especially in the Libellulidae. The nymph molts
several times after eclosion before the rudiments of the wings appear
as minute ridges on the dorsum of the mesothorax and metathorax.
They develop subsequently like the wings of heterometabolous insects
in general. As already noted, the crossing of the radial sector over
the media can not be followed, and in only one genus, Lestes, is there
any recognizable portion of the radial sector. The character of the
tracheation of the wing-cases of several zygopterous nymphs is
shown in Figures 14-17.

Abdomen. — Very little can be said of the abdomen except tliat in
both the embryo and nymph the segments are about equal in length
and more or less cylindrical. Reduction in size, lengthening of the
segments, and flattening of the abdomen, together with the appear-
ance of dorsal and lateral spines, seem to be the developmental ten-
dencies in the nympli. The accessory genitalia of the adult show no
signs of development until near the last nymphal stage, but the ovi-
positor of the female appears early, at least in the Zygoptera. This
organ undergoes great modifications and specialization in the adult
Zj'goptera, but in the Anisoptera it is probably in the process of re-
duction and degeneration. The caudal tracheal gills of the Zygoptera
are present in the embryo, and at hatching they appear as cylindrical,
jointed, cerciform appendages. Brandt ('69) says that at a still
earlier stage the lateral pair of gills are fused, but this observation
has not been verified. There is also a pair of smaller cerci dorso-
laterad of the lateral gills, making five caudal abdominal appendages
in all. All five of these are represented in the Anisoptera by short
cerciform appendages which are frequently triquetal and often
sharply pointed at the apex. It is important to note that these ap-
pendages are never united in the nymphs of Anisoptera or in Zygop-
tera, but that in the adults of Anisoptera the ventral pair is sometimes
fused. In all families of Zygoptera, the superior abdominal ap-
pendages,'which replace the lateral gills, are greatly reduced, but in
some Anisoptera, family Aeshnidae, the lateral appendages are re-
placed in the adult by long, lateral, superior appendages resembling
gills. A fact which sheds light on the origin of the Odonata as a
whole, is the presence of lateral abdominal gills in the genus Cora of
Central America and Euphea of the Old World. The rectal gills of
Anisoptera have been thought to originate in the forms having tra-
cheae which anastomose on entering the walls of the rectum as in

452

most Agrionidae; but it is doubtful whether this fact is really im-
portant.

Some of the most interesting modifications of structure for com-
parison are found in the proventriculus. These were first investigated
by Ris ('96), who (liscovered interesting correlations between
the number of teeth and folds present and their supposed specializa-
tion in the different families. Conditions were simplest in the nymphs
of Agrionidae ; more highly specialized in the Coenagrionidae, Aesh-
nidae, Gomphidae, and Libellulidae. The adult structures were much
more complicated than those of the nymphs of the same families.

The following table will suffice to show the important ontogenetic
tendencies of living forms.

Table showing Oxtogenetic Tendencies of Ztgoptera

AS COMPARED WITH ANISOPTEBA

Ego

Nymph

Adult

Anisoptera

Zygoptera

Anisoptera

Zygoptera

Anisoptera

Zygoptera

Eyes dichoptie Eyes diehoptic

Labium cleft

Labial p a 1 p us
without fixed
books

Median lobe
without setae

Labial palpi
without setae

Antennae with
three segments

Labium cleft

Labial p a 1 p us
without fixed
hooks

Median lobe
without setae

Labial palpi
without setae

Antennae with
three segments

Eyes dichoptie

Labium s 0 m e-
times slightly
ck'ft, never
deeply

Mandibles not
divided at tip

Labial p a 1 p us
without fixed
hooks

Median lobe
with or with-
out setae in

rows

Labial palpi
with or with-
out setae

Antennae with
3-7 segments

Epicranial su-
ture traceable

Furcae of meta-
stornum often
indistinct

Interpleural su-
ture indistinct

Eyes dichoptie

Labium s 0 m e-

tinics deeply
cleft

Mandibles a 1 -
ways divided
at tip

Labial p a 1 p us
with two fixed
hooks

Median lobe
^■ith or with-
out setae in

rows

Labial palpi
with or with;
out setae

Antennae with
3-7 segments

Epicranial su-
ture traceable

Furcae of meta-
sternum never
indistinct

Interpleural su-
ture never in-
distinct

Eyes sometimes Eyes dichoptie.
dichoptie, usu-
ally holoptic

Labium s 0 m e-
times slightly
cleft

Mandibles a 1 -
ways divided
at tip

Labial p a 1 p us
with one fixed
hook

Median lobe
with setae, but
not in rows

Labial palpi
without setae

Antennae with
4—7 segments

Epicranial su-
ture traceable
with difficulty

Furcae of meta-
sternum c 0 n -
cealed

Labium usually
deeply cleft.

Mandibles al-
ways divided
at tip.

Labial palpus
with one fixed
hook.

Median lobe
with setae, but
not in rows.

Labial palpi
without setae.

Antennae with

4-7 segments.

Epicranial su-
ture traceable 1
with difficulty.

Furcae of meta-
sternum c o n -
cealed.

453

Table showing Ontogenetic Tendencies of Zygoptera.
AS COMPARED WITH Anisoptera — Continued

Egg

Nymph

Adult

Anisoptera | Zygoptera | Anisoptera | Zygoptera I Anisoptera I Zygoptera

Mesepisterna us
ually separated

M e s e pisterna
a d j a cent or
separated

Abdomen cylindrical and about
equal in diameter throughout ;
of the same diameter as the
thorax

No tracheal gills jTracheal gills
but a long present
caudal projee '
tion

M e s e p isterna
usually separat-
ed

Wing-cases un-
equal in size

Trachea of ra-
dial sector
crossing media

Venter flat-
tened, abdo-
men much
broader than
thorax

No tracheal
gills

Ovipositor d e -
veloped late or
wanting

Rectal gills
present

Folds of pro-
ventriculus: 4
large; 4 small |

M e s e pisterna
a d j a cent or
separated

Wing-eases un-
equal in size

Trachea of ra
dial sector not
crossing media

Abdomen of the
same diameter
as the thorax

Tracheal gills
present

Ovipositor d e ■
veloped early

Rectal gills ab-
sent

Folds: 4 large,
4 small; or 8
large, 8 small

M e s e pisterna
adjacent and
fused

Wings unequal

Radial sector

crossing media

Abdomen wid-
ened at differ-
ent points, us-
ually of small-
er d i a m e ter
than thorax

No tracheal
gills

Ovipositor some-
times well de-
veloped ; u s -
ually wanting

M e s e pisterna
adjacent and
fused.

Wings unequal.

Radial sector
crossing media.

Abdomen equal
t hroughout;
always of
smaller diame-
ter than tho-
rax.

No tracheal

gills.

Ovipositor a 1 -
ways well de-
veloped.

Rectal gills Rectal gills
absent absent.

Folds: 4 large,
and 4 small

Folds: 8 large,
and 8 small.

PHYLOGENETIC COMPARISON OF ZYGOPTERA AND ANISOPTERA

. Several important theories and rules of procedure should be men-
tioned before undertaking a discussion of the suborders from a phylo-
genetic standpoint.

I. — Ontogeny repeats phylogeny. This is a well-recognized prin-
ciple and is the foundation of much phylogenetic work.

II. — All testimony should be corroborative if properly under-
stood ; or in other words, there should be no real conflict in the phylo-
genetic evidence obtained from different sources.

454

III. — The stem must be determined. Before an agreement can be
reached as to the phylogenetic status of any form, there must be
agreement as to what constitutes specialization, and what generalized .
conditions. Suppose, for example, that within an order of insects
there are species with two types of wings — one having numerous
cross-veins and the other but few ; which is the more specialized ? It
is possible for either type to have been derived from the other or
both to have arisen from a third extinct form. One may have be-
come specialized "by addition" and the other "by reduction". In this
case it is evident that the stem must first be determined beTore the
degree of specialization of either form can be stated with accuracy.

IV. — All possible elmractcrs should be taken info account, and a
decision concerning the rank of the group should be based on a study
of the whole organism. This method should be followed in view of
the fact that the same degree of specialization in structure is not
usually found simultaneously in different parts of the body, and it is
always to be preferred to the method of determining specialization
or generalization of a group of organisms by the study of a few
characters.

V. — The forces i(.<hich produce modification in structure should
be recognized if possible and their effect upon structure determined.

In the following comparisons the various characters will be con-
sidered separately and, where possible, the stem fonp will be men-
tioned and the reasons given for so regarding it. For convenience,
the division of the suborders into families as outlined by Handlirsch
('o6-'o8) and Muttkowski ('lo) will be followed, the Zygoptera be-
ing divided into the Agrionidae and Coenagrionidae ; the Anisoptera,
into the Aeshnidae, Gomphidae, and Libellulidae.

Egg

I. — Eggs of the Odonata are of two types; one long and some-
what cylindrical in shape, the other ellipsoidal and short. The dif-
ferences in shape are the result of different methods of oviposition.
The ellipsoidal form would seem to be the more primitive, judging
from a general knowledge of the eggs of various orders of insects.
No definite proof of this can be given, but a comparison with the
eggs of the Aptervgota and the lower Arthropoda indicates that the
ellipsoid is probably the stem type. This is. however, in direct con-
tradiction to the argument found in the reduction of the ovipositor,
since the species with specialized or reduced ovipositors lay ellipsoidal
eggs. Disregarding the latter argument and considering the cllipsoi-

455

dal egg as the primitive type, the series from lowest to highest would
be something hke the following: Libellulidae, Gomphidae, Aeshni-
dae, Agrionidae, and Coenagrionidae.

Nymph

2. — The most striking differences in nymphal characters are
found in the shape of the body. Zygoptera are without doubt near-
est the primitive Campodea type, and Anisoptera show a marked
deviation which is possibly due to the habits of life. This interpreta-
tion is supported by the embryonic stage, in which the body shape is
essentially campodeiform in both suborders.

3. — The compound eyes of all forms are specialized, but the line
of descent is not difficult to follow. The primitive type is found in
the embryo, which has small circular eyes on the lateral aspects of
the head. The nearest approach to this is found in the eyes of zygop-
terous nymphs ; the farthest away from it, in the Anisoptera, where
the eyes show a tendency to become dorsal in position. The cause of
the modification is unknown, but may be due in part to their habits,
the Anisoptera being mud-inhabiting to a large extent and needing
eyes on the dorsum of the head. Another cause may possibly be
found in the accelerated development of the greatly enlarged eyes of
the adult. In respect to shape and position of the compound eyes,
then, the Anisoptera should be regarded as the more highly special-
ized group.

4. — The antennae show important lines of development. The
primitive antennae of the embryo consist of three segments, the sec-
ond segment being the longest. A great lengthening of the first seg-
ment is the main line of specialization, and this occurs only in
Zygoptera in the familv Agrionidae. The antennae nearest the em-
bryonic type are found in the Gomphidae ; next in order are the
Aeshnidae, then the Libellulidae, and, finally, the Coenagrionidae and
the Agrionidae.

5. — The labium shows the more primitive condition in Zygoptera,
where the median lobe is deeply cleft in the family Agrionidae. Gra-
dations in complexity are found in a reduction in the depth of the
cleft, and the line of specialization may be followed through the fol-
lowing series, beginning with the least specialized : Agrionidae,
Coenagrionidae ; Gomphidae, Aeshnidae and Libellulidae.

6. — Mental setae are lacking in the embryo and also in the nympKs
of Aeshnidae, Gomphidae, Agrionidae, and a few Coenagrionidae.
The cause of the production of mental setae is unknown. There

456

seems to be greater specialization in the shape of the labial palpi or
lateral arms in the Coenagrionidae, notably the Lestinae, than in any
other group. The simpler types are found in the Aeshnidae, Gomphi-
dae, and Agrionidae, and a highly specialized form again in the Libel-
lulidae.

7. — The condition of the maxillae and the mandibles in species
existing prior to the present time can only be surmised, since there
are no embryological or paleontological data on the subject. These
appendages are so nearly alike in shape in the two suborders that no
comparison can be profitably made.

8. — The primitive prothorax, according to both paleontological
and embryological evidence, was a simple ring of the same size as
the mesothorax and metathorax. Specialized conditions are found in
the Anisoptera where, owing to the size of the head and the growth
of the compound eyes, the cephalic part of the pronotum is depressed.
The condition of the prothorax is probably primitive in Zygoptera.
The sclerites are not as distinct in the Anisoptera as in the Zygoptera,
indicating that obsolescense of the sutures has begun in this suborder.

9. — The next feature of note is found in the interpleural suture.
Stages of disappearance occur in all Anisoptera, the suture being
completely lost in the LibclluHdae and perfectly distinct in all nymphs
of Zygoptera. The cause of this modification is unknown, but it is
probably due to the excessive development of the wing muscles with-
in the thorax. In respect to this feature, then, the primitive forms
are found in the Zygoptera; the specialized, in the Anisoptera.

10. — Another modification is found in the disappearance in the
Libellulidae of the metafurcal invaginations. The primitive condi-
tion or stem form is unknown, as is also the cause of the disap-
pearance. It is probable, however, that the type with distinct in-
vaginations is the more generalized, which places the Zygoptera, the
Aeshnidae, and the Gomphidae much below the Libellulidae in position.

II. — In the shape of the wing-pads, the Anisoptera show more
conformity to the generalized types occurring in Plecoptera and Or-
thoptera than do the Zygoptera ; and they must be regarded as gen-
eralized in this respect.

12. — The simplest al)domcn, judging from embryological studies,
is a cylindrical portion of about the same diameter as the thorax.
The abdomen is much modified in all Anisoptera, where it is enlarged
and the venter flattened. The Zygoptera are generalized in this re-
spect, and a series showing progressive specialization in this single
feature would be as follows: Agrionidae, Coenagrionidae, Aeshni-
dae, Gomphidae, Libellulidae.

457

13- — The caudal tracheal gills of Zygoptera must be considered a
simple or stem character. This view is supported by much evidence
from embryological studies and the presence of one or two living
forms in which the gills are decidedly cerciform and cylindrical. The
modification into flat plates is undoubtedly specialization, but the re-
duction of the abdominal appendages in the Anisoptera indicates
further specialization of a different kind. Changes in shape of the
zygopterous appendages are proI:)ably due to a change from terrestrial
to aquatic habits very early in the history of the group. If we con-
sider that the anisopterous appendage has been derived by progres-
sive reduction, the following should be the order of development :
cylindrical cerci, flattened cerci, and reduction of cerci to short ap-
pendages similar to those in all Anisoptera. If, however, the gills be
regarded as derived from shorter caudal appendages, the Anisoptera
have the primitive types and the Zygoptera are highly specialized in
their elongate, flattened appendages. The presence of cylindrical
cerci as a primitive character seems to have the greatest amount of
embryological evidence to support it.

14. — The abdominal gills of Cora and Euphea of the Zygoptera
also afford comparative evidence as to the age of this suborder. Here
there are remnants of lateral, cylindrical gills on the abdominal seg-
ments. There seem to be embryological data sufficient to prove that
these lateral gills represent the appendages of forms more primitive
even than the Insecta.

15. — The oldest fossil Odonata showing ovipositors had the char-
acters of both Zygoptera and Anisoptera, and it is probable that the
stem forms had true -ovipositors. The simplest type of ovipositor
among living Odonata is found in the nymphs of Zygoptera and
consists of a number of similar valves. The reason for the reduction
of the ovipositor in the adults of Anisoptera lies in the acquisition
of the aquatic habit and the consequent difficulty of depositing eggs
in plant tissue. It is reported that some Zygoptera do not insert the
egg in the plant but merely press it against the plant and allow it to
drop to the bottom ; and this appears to be a transition stage from
the endophytic to the exophytic method of ovi.position. Reduction
of the gonapophyses, then, means specialization, and the order would
be — Zygoptera, generalized ; Anisoptera, specialized.

Adjilt

16. — So many different lines of specialization seem to have taken
place in the development of the head capsule of the adult that it is

458

almost impossible to arrive at any conclusion as to its simplicity or
complexity. Suffice it to say that paleontological and embryological
data prove that there are primitive types in both Zygoptera and An-
isoptera. In the holoptic condition of the compound eyes, however,
there is a more definite character. As already stated, the primitive
type is dichoptic; and beginning with this condition, which we find
most closely approximated in the Zygoptera, there are all degrees of
dichoptic and holoptic states. The cause of the modification is prob-
ably due, in the adult, to the increased power of vision made neces-
sary by the greatly increased powers of flight and the fact that the
insect captures its prey while on the wing. An excellent series of
.specializations is to be had in the following families, the Zygoptera
being the more generalized : Agrionidae, Coenagrionidae ; Gomphi-
dae, Aeshnidae, and Libellulidae.

17. — The antennae, as already noted, show marked reduction in
size from those of the nymphs. The nearest approaches to the primi-
tive, seven-segiiicntcd cnndition are found in the Libellulidae and
some of the Aeshnidae, where six segments are often encDuntered.
Most representatives of the remaining families have the segments
quite consistently reduced to four. The adults of the Agrionidae
have the most highly specialized antennae; and in a series showing
increasing specialization the Libellulidae would be the more gener-
alized. The following is such a series based upon antennal structure :
Libellulidae, Aeshnidae, Gomphidae, Coenagrionidae, and Agri-
onidae.

18. — The front shows great deviation from the simpler forms in
the majority of the Anisoptera, and the mound-like elevation of this
part is characteristic of most families of this suborder.

ig. — The mandibles of the adult have apparently undergone no
modification of importance in the different families. They are so'
nearly alike in all groups that a comparison will not be attempted.

20. — The maxillae of the adult have likewise undergone little
modification in the different families, but the form nearest the primi-
tive type present in Plecoptera nymphs is found in the Gomphidae.

21. — The labium shows the same deviations from the primitive
condition as were described for the nymph. Looking ujion the depth
of the median cleft as a measure of generalization, the Agrionidae
would be considered as the more generalized. Next in order are the
Coenagrionidae and, following these, the Aeshnidae, Gomphidae, and
Lii^ellulidac. The labial palpi retain about the same degree of
specialization that occurs in the nymphs; and the same sequence of
family specialization as has been described for the nymphs is present
in the adults.

459

22. — As regards the form of the microthorax, no stem can be de-
termined, but it is probable tliat there has been much more speciaUza-
tion in the Anisoptera than in the Zygoptera.

23. — The degree of complexity of the prothorax as a whole is
difficult to determine. Many sexual modifications occur in the adults
which must be considered as secondary characters having little bear-
ing on phylogeny. The distinctness of the propleural suture, how-
ever, is of some value. In Zygoptera, this suture is most distinct in
the Coenagrionidae (Lestinae) and is moderately so in the Agrioni-
dae. In the Anisoptera it is most distinct in the Aeshnidae, but is
as a rule indistinct in other families. According to this character the
Zygoptera seem to be generalized; the Anisoptera specialized.

24. — In the mesothorax and metathorax the most important fea-
ture, aside from the wing structure, is to be found in the interpleural
suture. As already mentioned, this suture shows no sign of disap-
pearance in any of the nymphs of Zygoptera, and still remains undi-
minished in distinctness in the adults of the family Agrionidae. In
the Coenagrionidae, however, the interpleural suture becomes obsolete
in great measure. In both nymphs and adults of Anisoptera, it is
indistinct. The degree of its distinctness is therefore an excellent
character for determining the degree of specialization or generaliza-
tion of the species and consideration of this fact alone leads to the
conclusion that the Zygoptera are the more generalized.

25. — The varying degrees of approximation of the mesepisterna
and the metepimera indicate an entirely different line of development
from that shown in 24. The primitive condition is one in which the
two mesepisterna and metepimera are separated by considerable inter-
vals, as has been shown for the nymphs. The approximation of the
metepimera on the ventro-meson is a much later development and does
not appear until the adult stage. Nevertheless, nearly the same line of
specialization occurs as in the former case, the simplest conditions
being found in the Aeshnidae and the Agrionidae, the more complex
in the Gomphidae, Libellulidae, and Coenagrionidae.

26, — The development of the mesothoracic spiracles indicates that
the Libellulidae, again, are the most specialized, with the Agrionidae
and Aeshnidae at the bottom of the series. Tlie size of the spiracles
in Libellulidae and the degree of their approximation on the dorso-
meson warrant this assumption, the primitive types being small in size
and rather widely separated, as in Zygoptera and some Aeshnidae.

27. — A line of specialization is found in the length of the thora.x
caudad of the metacoxae. In this the Coenagrionidae and Agrionidae
are decidedly the more specialized.

460

28. — More use has been made of the wings and wing venation in
following out genealogical development than of any other single por-
tion of the body of the dragon-fly. The evidence is conflicting in
many respects, and in coming to conclusions all characters must be
taken into account. The most noticeable feature of the wing venation
is the crossing of the longitudinal veins Rs and M. This condition
is so unicjue that it was doubted or denied for a long time, and not
until it was traced from its beginning in the tracheae of the nymph
was it generally accepted as true. ^lany of the changes in the wing
venation may be considered as the result of stress on particular por-
tions of the wing surface. The development has followed two lines
of specialization ; one of them a reductive process, exemplified in the
Zygoptera, the other additive, exemplified in the acquisition of im-
portant wing-braces in the wings of Anisoptera.

The main points regarding the specialization of the odonate wing
are stated in the following tabulation.

Generalized conditions

1. \\'^ings of equal size and

venation.

2. Wings not petiolate.

3. Nodus not retracted ;

near the middle.

4. No reduction in number

of cross-veins.

5. Arculus near the base of

the wing.

6. No reduction in the

number of antenodals.

7. No reduction in the

number of postnodals.

8. Rs traceable throughout

its course.

9. M2 not arising distad of

the nodus.
10. Rs separating from Mo
near the nodus.

>>

c

TS

u

^

0

.4->

c
0

^

>,

'M

^&5

•d o

Developmental tendencies ti ■"

c o

Wings of unequal size and Yes Yes

venation.
Wings petiolate. Yes Yes

Retraction of the nodus to- Yes Yes

wards the base.
General reduction in number Yes ?

of cross-veins.
Retreat of the arculus distad Yes Yes

from base.
Reduction in number of an- Yes ?

tenodal cross-veins.
Reduction in nhmber of Yes ?

postnodal cross-veins.
Rs not traceable throughout No Yes

its course.
IM; arising distad of the Yes ?

nodus.
Rs separating from IMo dis- Yes ?

tad of the nodus.

461

>.

4"^ i! bjo

"9 o "p c

Generalized conditions Developmental tendenaes V. ° X. o

CL, o & c

II. Quadrangle triangular. Quadrangle rectangular. Yes No

. 12. Mg and M4 not uniting M-, and M4 uniting distad of Yes Yes
distad of the arculus. the arculus.

13. Media at the top of the Media descending the arcu- Yes Yes

arculus. lus.

14. No development of the Development of the anal Yes Yes

anal loop. loop.

15. No matching of the Matching of the transverse Yes Yes

transverse cross-veins. cross-veins.

16. Pentagonal cells numer- Reduction in number of Yes Yes

ous. pentagonal cells.

17. Little reduction in the Reduction in the number of Yes Yes

number of rows of rows of cross-veins be-
cells and little retreat t w e e n all longitudinal
distad. veins and retreat distad of

the rows.

18. Nodus and arculus not Approximation of the nodus Yes Yes

approximated. and arculus.

19. Stigma long. Stigma short. Yes Yes

20. Stigma sometimes ab- Stigma always present. Yes Yes

sent.

The different families are specialized in the characters listed under
the figures following them : —

Coenagrionidae.— 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 16, 17, 18, 19, 20.

Agrionidae. — 11, 15, 16.

Aeshnide. — 2, 5, 11.

Gomphidae. — i, 5, 7, 11.

Libeflulidae. — i, 12, 13, 14.

From the above it will be seen that in wing venation the family
Coenagrionidae is by far the most highly specialized, while the Agrion-
idae, Aeshnidae, and Gomphidae are about equally specialized, and
the Libellulidae are intermediate in position.

29. — The primitive abdomen consisted of a cylindrical portion of
the same diameter as the thorax; and the same is now essentially true
of the nymphs of Zygoptera. In the adults, however, the diameter

462

of the segments has been reduced as compared with that of the thorax.
In the Anisoptera there are other modifications Ijesides the reduction
in diameter. Here, the abdomen is sometimes triangular in cross-sec-
tion, and different portions of the abdomen of the same species have
different (Hamcters. Considering shape alone, the following line of
development may be recognized, beginning with the more generalized :
Agrionidae, Coenagrionidae, Aeshnidae, Libellulidae, and Gom-
phidae. This order of specialization is followed throughout in the
aljdomcn.

30. — The approximation of the terga on the ventro-meson, is a
mark of specialization most frecjuently found in the Anisoptera, as is
also the appearance of the secondary ridges on the terga.

31. — The anal appendages of the abdomen are interesting, and
the line of specialization indicated by them seems to coincide in general
with that already outlined for the suborders in 29 and 30. The series
has already been given for the two groups in paragraph 13. Within
the Anisoptera, two different lines are found, both probably represent-
ing specialization. In one of these the inferiors are fused, as in the
Libellulidae ; in the other the superiors are enlarged and expanded, as
in the Aeshnidae. In the Zygoptera the forcipate appendages of the
Agrionidae probably represent the most primitive forms, and the short
and f recjuently greatly modified appendages of the Coenagrionidae, the
more highly specialized.

32. — Accessory male genitalia of the second segment are important.
The statement that this organ lias been derived from the sexual organs
of the progoneates is substantiated by the reported connection of the
proximal end of the penis with the visceral cavity. This occurs in
Zygoptera and seems not to have been observed in the Anisoptera,
the connection supposedly having been lost through specialization.
Further specialization has been suggested in the tracheation of the
appendages, which occurs in some Anisoptera according to Backhoff
('10) but not in Zygoptera. Other differences indicating specialization
in Anisoptera are to be noted in the segmentation of the penis and
in the position and connection of the seminal vesicle with the latter.
The structure of the hamulcs and the genital lobes, and of the portions
■)f the genitalia arising from the third abdominal segment, seems to be
simpler in the Zygoptera and not so much reduced or changed from
the original plan of the sterna of these segments. The tip of the intro-
mittent organ is much simpler in structure in the families of Zygoptera.

33. — As mentioned in paragrajjh 15, the presence of the ovipositor
in the earl}' stages of the nymphs of Zygoptera and its absence in the
nymphs of Anisoptera suggest that the anisopterous appendages have

463

been reduced from a primitive form similar to that of Zygoptera. This,
together with the evidence furnished by extinct species where adults
with wing venation similar to that of the Anisoptera had ovipositors,
proves fairly conclusively that the extant species without ovipositors
have undergone specialization by reduction.

34. — One of the most complete lines of specialization has been de-
termined by Ris ('96) for the structure of the proventriculus. He
found what he considered a primitive condition in the Zygoptera
(Agrionidae) in which there are sixteen internal folds. Specializa-
tion takes place by reduction, and there are eight folds in the Lestinae,
four in Gomphus and Aeshna, and none in Libellulidae, there being
instead four large symmetrical teeth.

35. — Specialization among the Anisoptera seems to be still further
indicated by the habits of the group, especially their habits of migra-
tion. The mere fact of migration is not important ; but the method
of flying in companies and particularly of so flying that there are reg-
ularly spaced intervals between the individuals is something which, if
true, is unic^ue in this order and in the class Insecta.

Considering the preceding characters as a whole, it will be found
that there are two orders of specialization which apparently proceed
in opposite directions. One of these begins with the Agrionidae of
the suborder Zygoptera and ends with the Libellulidae of the Anisop-
tera ; and the other begins with the Libellulidae and ends with the
Agrionidae. The characters mentioned in the various paragraphs
will now be assembled for a comparison of the number of generalized
features in each family. The families are listed below, and are usually
or frecjuently generalized in the characters discussed in the paragraphs
the numbers of which are placed opposite.

Agrionidae. — 2, 3, 5, 6, 8, 9, 10, 12, 13, 14, 15, 16, 18, 21, 22,
23, 24, 25, 28, 29, 30, 31, 12, 33, 34, 35.

Coenagrionidae. — 2, 3, 5, 8, 9, 10, 12, 13, 14, 15, 16, 18, 21, 22,
23, 24, 26, 29, 30, 31, 32, 33, 34, 35.

Aeshnidae. — 1,4, 6,' 10, 11, 15, 17,25,27,28.

Gomphidae. — i, 4, 6, 10, 11, 17, 20, 27, 28.

Libellulidae. — i, 11, 17, 27, 28.

From this it will be seen that the most generalized family is the
Agrionidae.. The evidence is such that it can not be doubted, and
it points to some form of the Agrionidae or related family as the stem
type. The following genealogical tree, based partly on Handlirsch
('o6-'o8), has been constructed after taking into accoimt all existing
evidence. Distance to the right indicates specialization; vertical dis-
tance, time.

464

>

Eras

Periods

3 S %

% " s

Recent

\\ / ///

Cainozoic

Quaternary

// I//

Tertiary

1/ 1/

Mesozoic

Cretaceous

/ ^

Jura^'^ic

v"

Triassic

o

Paleozoic

Permian

a.

Carboniferous

SulicarbiinifiTous

Classification

Some of the more important features use;d in the classification
of the nymphs of Zygoptera include the characters of the labium
and antennae, the nature of the caudal gills, and the armature of the
lateral keels. The classification of the adults depends upon the wing
venation and the anal appendages of the male, as well as on such
characters as the mesostigmal plates of the female, color, and the like.

The number of species occurring, or probably occurring, within
the state is forty-two, as follows. Those without asterisk have been
taken in adjoining states by other collectors; those with one have

465

been reported from Illinois; and those with two have been collected
by the writer or seen in collections actually made within the state.

**Agrion acquabile (Say)
**Agrioii macitlatum Beauvais
**Hetacrina americana (Fabri-

cius)
**Hctacrina titia (Drury)

*Lestes congener Hagen

*Lestes disjunctiis Selys
Lestes eurimts Say
**Lestcs forcipatiis Rambur

*L,estes inaequalis Walsh
**Lestes rectangularis Say
**Lestes uncatiis Kirby
**Lestcs nnguicitlatus Hagen
** Lestes tigilax Hagen
**Argia apicalis (Say)

Argia ftCmipennis (Burmeis-
ter)
** Argia moesta piitrida (Hagen)

* Argia sedula (Hagen)
** Argia tibialis (Rambur)
** Argia I'iolacca (Hagen)
**Enal!agnia antennatnm (Say)

*Biiallag}iia aspersnm (Hagen)
**EnaUagma calverti Morse

**EnaIlagiiia cantnciilatuvt Morse
**Bnallagnia ciznle (Hagen)

Enallagma cyathigerum (Char-
pentier)

Enallagina divagans Selys

Enallagma douhledayi Selys
**Enallagma ebriiim (Hagen)
**Enallagma exsulans (Hagen)
**Enallag!iia gcminatum Kellicott
**EiuillagjHa Imgeni (Walsh)

Enallagma piscinarium W i 1 -
liamson
**Enallagina pollntum (Hagen)
**Enallagiiia signatmn (Hagen)
**Euallagina traz'iatum Selys
**Nclialciinia irene Hagen
**Ampliiagrion saucium (Bur-

meister)
**Chroniagrion conditurn (Ha-
gen)

Ischnitra kcUicotti Williamson
**Isclimira posita (Hagen)
**Ischniira verticalis (Say)
**Aiionialagrion hastatiim (Say)

The division of the suborder into families and the arrangement
of genera followed by Muttkowski ('lo) have been adopted and are
herewith reproduced, including only the genera that occur in Illinois.

Family

Agrionidae

Subfamily
■i. Agrionii

lonmae

{

Coenagrionidae

Lestinae

Coenr.grioninae

Genus
Agrion
Hetaerina

Lestes

Argia

Enallagma

Nehalennia

Amphiagrion

Chromagrion

Ischnura

Anomalagrion

4G6

In the following descriptions "length" refers to the length of
the body without appendages, and does not include caudal gills, anal
appendages, or antennae. In the color descriptions, where suitable
material was at hand, the colors were matched with colors given by
Ridgway in his "Color Standards and Color Nomenclature" ('12),
and the names of colors which appear in parentheses are from that
author.

Family AGRIONIDAB

The nymphs of this family are easily distinguished from those
of the Coenagrionidae. The three-sided gills, the deeply cleft median
lobe of the labium, the large basal segments of the antennae, the un-
equal length of the gills, and the heavy and sprawling appearance of
the legs are characteristic.

The adults are, as a rule, bright or strikingly colored, such colors
as metallic green and carmine I)cing common. A large number of
antenodal cross-veins between costa and subcosta and the presence of a
distinct interpleural suture are also diagnostic*

Subfamily AGRIONINAE
Key to Genera

NYMPHS

a. Median cleft of median lobe of labium extending pro.ximad of the

articulations of the labial palpi ; body color usually dark Agrion.

aa. Median cleft not c.\1 ending proximad of the articulations of the labial
palpi ; body color usually light Hetacrina.

ADULTS

a. Wings with the basilar space, cell first M, without cross-veins; meta-

pleural suture onlj' with a pale stripe Agrion.

aa. Wings with a basilar space provided with ei'oss-voins ; mesopleural,
interpleural, and metaidcural sutures with pale stripes. . . .Hetaerina.

Genus Agrion Fabricius

In the nymph the median lobe of the mentum is provided with a
deep cleft which extends far pro.ximad of the articulations of the

"Only one genus in this family is known in which the interpleural suture is
not well developed, and since that genus does not occur in the United States, this
character has been included in the family description.

467

labial palpi. The caudal gills are dark, witli a light transverse band
about the middle of their length. The caudo-lateral margins of the
head are elevated to form a short, sharp tubercle. The nymph of but
one species has been available, and a study of this, together with a
corriparison with Hetaerina, has afforded possible generic characters.
The adults are uniform in color, usually dark metallic green or
blue, and black, and the wings are broad, with a large number of
cross-veins, the basilar space, however, being free from them. The
legs are provided with a double row of ventral setae which are usually
several times longer than the spaces between their bases.

Key to Species

a. Interstermim metallic green ; wings of male smokj' only on the apical
tliird; female with a sharp spine on the dorso-apical margin of the

tenth abdominal segment; latero- ventral margins of thorax pale

aequabile.

aa. Intersternum entirely black ; wings of male wholly dark ; female with
only a short blunt projection on the dorso-apical margin of segment
ten ; latero-ventral margins of thorax dark maculatum.

Agrion aequabile (Say)

Nymph. — The nymph of aequabile has not been available for
study, but this species and its variety yakinia have been described by
Needham ('03:223,224) and Kennedy ('15:338). It seems to be
nearly identical with vmeulattim. The length of the basal segment of
the antenna is used by Needham for its separation from maculatum,
but this character can not be used for the separation of the variety
yakima. The length is somewhat greater and the gills somewhat
longer than those of m-aculatum, but this character also is of doubtful
importance, and further study of the two species should be made to
determine the essential differences.

Adult; Male. — Color, metallic green and blue.

Head : mouth-parts black, median lobe of the labium triangular
in outline, basal segment of the palpus very broad, distal segment
small, cylindrical, longer than the fixed hook of the first; palpiger
about one-third the length of the first segment ; antennae entirely
black ; clypeus and labrum black ; the front and genae metallic green
and thinly clothed with dark hairs.

Thorax metallic green, black and green below ; pronotum with
the caudal margin entire, the caudal lobe convex and projecting caudo-
dorsad ; proepimeron distinct ; cephalic portion of the prescutum large,

468

subtriangular, and depressed; paraptera subtriangular, each half with
the caudal margin sinuate and slightly emarginate on the lateral half;
intersternum green ; legs entirely black, the ventral setae much longer
than the distances between their bases, the setae of the front femora
twelve to fourteen in each row ; wings transparent, except the apical
third (Fig. 73), which is smoky, about one-third as broad as long,
slightly narrower than the wings of A. maculatum; stigma wanting,
antenodals of the front wing thirty-two.

Abdomen green and blue ; sternum of segment ten and the apical
third of sternum nine buff-colored ; anal appendages (Fig. 117) mostly
black, the superiors wholly black, long and curved, tuberculate on the
lateral surfaces, and slightly emarginate on the mesal margins at the
middle; inferiors black at the apex, paler at the base, nearly as long
as the superiors, and provided with a minute apical point directed
mesad; parameres of the ninth segment small (Fig. 118).

Female. — Color, metallic green.

Head : proximal half of the second antennal segment with a pale
lateral spot ; labrum buff-colored on each side, and with a median hour-
glass-shaped black mark ; exposed portions of the mouth-parts, in-
cluding the mandibles and their trochantins, buff.

Thorax : latero-ventral margins pale, including the cephalo-
ventral margins of the mesepisternum, caudal half of the mesinfraepi-
sternum, a stripe along the metapleural suture extending more than
naif- way from the cephalic margin to the wing bases, and the ventral
and cephalic margins of the metepimera; intersternum green; wings
slightly smoky, but not darker on the apical third, stigma present,
white.

Abdomen metallic green and black, the apical portion dull and
paler below; tergum of segment ten with a prominent mesal ridge
which is produced into a long spine at the apex (Fig. no); anal
appendages consisting of conical superiors, double the length of the
blunt inferiors; ovipositor reaching to the middle of the tenth seg-
ment, the prostyles extending to its apex (Fig. no).

Measurements

Length, $ 49 mm.

Length, 9 44 mm.

Length of abdomen, S .38 mm.

Length of abdomen. 9 " 34 mm.

Length of hind win^, ?i 32 mm.

Length of hind wings, 9 29 mm.

Width of hind wings, $ 9 mm.

Width of hind wings, 9 8 mm.

. 469

The species is apparently rare in Illinois though reported from
this state by Williamson (oo). The above description was made from
three specimens in the collection of the Illinois State Laboratory of
Natural History, two of which bear the label "Mass.". I have not
seen the species within the state.

Agrion maculatum Beauvais

Nymph. — Color, dark brown.

Head pentagonal, little contracted behind the eyes; eyes black,
a black stripe nearly the width of the eye extending to the caudal
margin of the head, and another stripe extending from the antennal
fossae to the eyes; proximal segment of the antennae thick, about as
long as the head, and usually slightly longer than all the remaining
segments together; labium with the median lobe deeply cleft, the
cleft extending proximad of the articulations of the labial palpi (Fig.
8) ; proximal segment of the palpus with three immovable end-hooks
and two small setae near the base of the distal segment of the palpus.

Thorax : prothorax with a broad dark line on each lateral margin
which is continuous with the dark line on the side of the head ; legs
slender, the femora with a whitish band on the apical third, with
a narrower brownish band proximad of the white one, and a distal
brownish band extending to the apex of the segment; tibiae without
heavy setae ; tarsi short ; wing-cases broad and extending in full-
grown nymphs as far as the fourth abdominal segment.

Abdomen subcylindrical, dark, and without distinct lateral keels;
apical margins of the terga with about four dark spots on the dorsum ;
lateral tracheal gills three-sided, somewhat blunt, with a white trans-
verse band near the middle of their length; median gill flat, shorter,
with a similar cross-band at the middle and another faint band beyond ;
marginal setae of the median gill long and slender, extending entirely

around the gill.

Measurements

Length 20 mm.

Length of abdomen 15 mm.

Length of lateral gills 10-12 mm.

Length of metathoraeie wing-cases 6 mm.

Length of median lobe 4.5 mm.

Width of median lobe 1.3-3 mm.

Adult; Male. — Color, metallic green or blue.
Head green ; labium black, the median lobe subtriangular in out-
Hne, the cleft extending slightly less than half the distance from apex

470

to base; proximal segment of the labial palpus liroad, black, the
palpiger short, al)iiut one-half the length of the first segment measured
from the point of articulation to the base of the second segment, the
fixed hook nearly as long as the distal segment of the palpus ; antennae
black ; clypeus and labrum metallic green or black ; front, together
with the clypeus and lalirum, thinly clothed with Ijlack setae; eyes
black or slate-colored.

Thorax green above, black below ; pronotum with the caudal
margins entire, the caudal lobe convex and projecting caudad and
dorsad ; procpimeron distinct ; cephalic portion of the mesoprescutum
subtriangular, depressed ; dorsal carina distinct, black ; paraptera sub-
quadrangular, the caudal margins emarginate on the lateral third;
metepimera broader ailjacent to the wings; ventral portion of the
metepimera and the intersternum wholly black and subshining; legs
black, the setae also black and longer than the space between their
bases; anterior femoral setae fourteen or fifteen on each side; tarsi
black; wings very dark, almost opacjue, and about one-third as wide
as long; stigma wanting; antenodal cross-veins twenty-seven.

' Abdomen nearly cylindrical, glabrous and faintly striated trans-
verselv ; superior anal appendages long and black, tiic lateral surfaces
tuberculate, the mesal surfaces emarginate at about the middle ; in-
feriors nearly as long as the superiors, straight and with a small apical
hook directed mesad (Figs. 139,139a).

Female. — Color, metallic green.

Head not essentially different from that of the male.

Thorax : wings pale brown, darker at the tips, transparent ; stigma
present, white; antenodal cross-veins 23 to 24.

Abdomen much shorter than that of the male; anal appendages
consisting of conical superiors more than twice the length of the blunt
inferiors; ovipositor (Fig. 109) with broad lateral valves reaching
about to the apex of segment ten, the prostyles rod-like and slightly
curved.

Measurements

- Length, S 1 .46 mm.

Length, 2 41 mm.

Length of abdomen, $ 38 mm.

Length of abdomen, 9 32 mm.

Length of hind wings, $ 29 mm.

Length of hind wings, 9 30 mm.

Width of hind wings, S 10 mm.

Width of hind wings, 9 10 mm.

471

The nymphs of this species may be taken in the clearer and
swifter streams of IlHnois, though not often in very great numbers.
The adults do not wander far from the habitat of the nymphs and
their period of flight seems to be largely limited to a short time in
early summer. The species is supposed to have a northerly distribution,
but has been taken near the southern boundary of the state. Several
nymphs taken at Urbana early in June emerged June lo, 191 5, and
subsequent collections of adults show that the insect flies until early
fall, although the period of maximum abundance lies between the
middle of June and the middle of July.

Specimens have been seen from Havana, Muncie, Oregon, Peoria,
Urbana, Cook County, and McHenry County.

Genus HetaERina Hagen

The nymphs of this genus have shallow mental clefts, and have
the margins of the pronotum prominently elevated, and the margins of
the lateral gills marked with black or dark spots.

The adidts are characterized by cross-veins within the basilar
space and by pale stripes on all of the pleural sutures of the thorax.

Key to Species

MALES

a. Bases of hind wings tinted with carmine similar to that of the front

wings ; legs striped, buff and black or dark brown americana.

aa. Bases of hind wings tinted with brown ; legs entirely dark, not
striped titia.

FEMALES

a. Mesepisterna and mesepimera of the thorax without elongate spots of

green ; uniform bronze americana.

aa. Mesepisterna and mesepimera of the thorax with elongate spots of
green titia.

Hetaerina AMERICANA Fabricius

Nymph. — Color, brown or greenish.

Head pentagonal, about as long as broad ; proximal segments of
the antennae nearly twice as long as all the remaining ones together;
eyes black or dark; labium (Fig. 9) thickset, the cleft of the median
lobe hardly extending proximad of the articulations of the labial palpi ;
labial palpi with three end-hooks and five or six small setae at the

472

base of the distal segment ; caudo-lateral margins of the head forming
a Hunt tubercle.

Tluirax twice as long as broad, a dark lateral line occurring in
some individuals, extending from the eyes to the bases of the second
pair of wing-cases, though, as a rule, this is much less distinct than
in Agrion ; lateral margins of the pronotum distinctly elevated,
scalloped, and the margins produced at two points on eacli side to form
tubercles (Fig. 23) ; legs without heavy setae, usually light in color.
In younger and more plainly marked specimens the proximal half of
the femur is dark brown ; this is followed by a light band, beyond
which the femur is again l)rown to the apex ; tibiae with three faint,
dark rings, the bases and apices also dark; tarsi light in color except
the apical half of the third segment and the tarsal claws, which are
usually black.

Abdomen : lateral keels feebly developed, not armed with setae
though ending abruptly on the apex of segment nine in a short blunt
tubercle ; ovipositor short and extending hardly caudad of the apex of
the ninth abdominal segment; lateral gills three-sided, the median one
flat and considerably shorter than the lateral ones; median gill dark
along the axis nearly to the apex and with three dark cross-bands;
axes of lateral gills sometimes dark, though more frequently the whole
gill is light brown or buff and the three margins arc each marked with
three dark spots (Fig. 79).

Measurements

Length 23 mm.

Length of abdomen 12 mm.

Length of lateral gills 9-10 mm.

Length of metathoraeic wing-eases. . . .6 mm.

Length of median lobe 4 mm.

Width of median lobe 1.3-3 mm.

There seems to be a great deal of variation in the color markings
of the nymph, csjiccially in the amount of dark pigment, and specimens
may be taken which are either practically without body markings of
any sort or are so dark and plainly marked as to make the collector
think he has taken another species.

Adult; Male. — Color, bronze and metallic green; bases of the
wings carmine.

Head metallic bronze; median lobe of the labium subtriangular
in outline; labial palpi broad, the terminal segment black and as long
as the fixed hook of the first segment ; front, vertex, clypeus, and

473

labrum, thinly pilose ; postclypeus metallic green with a small buff spot
on the dorso-lateral margin, the anteclypeus with a triangular, median
light spot, the remainder dark ; labrum buff, but provided with a me-
dian, circular, black spot ; exposed portions of the mandibles and their
trochantins buff; eyes uniform brown.

Thorax : prothorax bronze and black, thinly pilose ; caudal lobe
of the pronotum convex and projecting caudo-dorsad, the caudal
margin entire ; proepimeron distinct ; pleural sutures all marked with
buff-colored stripes, the interpleural suture distinct, cephalad of the
metathoracic spiracle ; metepimera largely buff but with a median longi-
tudinal stripe of bronze; intersternum with two dark spots on the
cephalic border which unite with a dark line covering the suture
caudad of it and between the epimera ; paraptera subtriangular, black,
the caudal margins nearly straight ; legs striped, buff and black, the
coxae and trochanters buff with a few darker spots, the femora and
tibiae mostly dark with lighter stripes on the caudal surfaces, the front
femora with nine or ten setae in each row, and the tarsi and claws
black ; wings clear, the basal fourth, or more, bright carmine, anteno-
dals of the front wing nineteen or twenty, the stigma much longer
than the cell caudad of it (Fig. 78).

Abdomen metallic green or reddish brown, dull with age; seg-
ments three to seven with pale basal rings, interrupted on the dorso-
meson, the lateral surfaces of terga two to seven with a pale longi-
tudinal stripe from base to near apex ; first tergum with a pale lateral
apical spot; anal appendages (Figs. 34,38) with the superiors twice
as long as the inferiors, curved and somewhat expanded at the apex,
the lateral margins tuberculate, the mesal margins with two rounded
knobs.

Female. — Color, metallic green and in general lighter than that
of the male.

Head as in the male except that the antennae have the basal seg-
ment entirely pale ; postclypeus with a large transverse green spot, and
the labrum with a black mesal spot on the dorsal margin.

Thorax with the dorsal carina lined with buff, the pleural sutures
with much broader stripes than those of the male; wings (Fig. 74)
without carmine at the base, but slightly smoky on the basal third
and along the costal margin ; stigma white, and the antenodal cross-
veins about twenty-one in number.

Abdomen metallic green above, the lateral surfaces of the terga
with darker apical spots on segments one to nine, and terga two to
seven with narrow basal rings of paler color which are interrupted
on the dorso-meson; anal appendages of the usual type; ovipositor

474

(Fig. 112) with broad lateral valves, which are serrate on the ventral
margin and extend to the apex of segment ten ; prostyles slender,
rod-like and bent ventrad at the apex (Fig. 41).

Meastirements

Length, S 44 mm.

Length, 9 42 mm.

Length of abdomen, S 36 mm.

Length of abdomen, 2 32 mm.

Length of hind wings, S 28 mm.

Length of hind wings, 9 29 mm.

Width of hind wings, $ 6 mm.

AVidth of hind wings, 9 6 mm.

This species is common along the drainage ditch north of Urbana.
Nymphs collected May 2y and 29, 191 5, emerged June 19. The species
flies until late in October and specimens have been taken as late as
October 22. It is apparently limited to the northern half of the state,
though probably occurring wherever conditions are favorable.

Specimens have been seen from Galena, Havana, Muncie, Oregon,
Peoria, Savanna, Urbana, and McHenry County.

HetaERINA TITia (Drury)

Nymph. — Unknown.

Adult; Male. — Color, very dark green and brown.

Head dark brown, faintly metallic; labium with subtriangular
median lobe, the palpi with broad black proximal segments, and black
distal segments about as long as the fixed hook of the pro.ximal seg-
ment; antennae brown; clypeus and labrum shining; front with a
broad transverse buff stripe immediately above the clypeus, the front,
vertex, clypeus, and labrum pilose, the setae brown.

Thorax black and brown, slightly bronzed ; pronotum with the
caudal lobe somewhat pointed, convex, and projecting caudo-dorsad ;
proepimera distinct ; interpleural suture distinct ceplialad of the
spiracle; mesinfracpistcrnum buff, with a dorsal dark stripe; cephalic
shoulder of the mesepimcron light brown, the mesepisternum with a
greenish longitudinal stripe extending from the caudal margin nearly
to the spiracle; metepimcron with a median black stripe; intersternum
with two faint black spots near the cephalic margin; legs uniform
dark brown, the tibiae lighter in color than the femora, the setae of
the front femora in eleven or fourteen rrnvs, tarsi and claws black;

475

wings clear, the front wings carmine, and the hind wings brown at
base, the color, however, not occupying as much as one-fourth the
length of the wing; apices of the wings brown; stigma brown and
not longer than the cell caudad of it; front wings with about twenty-
four antenodal cross-veins.

Abdomen dark brOwn ; second tergum marked with a paler trans-
verse band beyond the middle, the lateral margins also pale; terga
three to six paler along the lateral margins, with narrow basal rings
interrupted on the dorso-meson; segments seven to nine inclusive all
dull black, the sternum of the tenth buff; anal appendages (Fig. 119)
consisting of heavy black superiors, more than twice as long as the
inferiors, and having a few tubercles on the lateral surfaces of the
apical half, the mesal surfaces with basal knobs and thick subapical
projections; inferiors dark brown, reddish at base, short, and with
small apical points directed dorsad.

Fcniule. — Color similar to that of the male.

Head similar to that of the male.

Thorax pale brownish, yellow, and green, the dorsal carina
black, the supraepisterna of the mesothorax with a median elongate
spot extending cephalad from the wing bases half-way to the cephalic
margin, the cephalo-dorsal angles being also green; mesepimera with
elongate spots about the middle and nearer the ventral than the dorsal
margin; wings without carmine, the bases with only a slight tinge of
brown ; stigma nearly white, and surmounting one to one and a half
cells; antenodal cross-veins of the front wing twenty-one, postnodal
cross-veins twenty-six.

Abdomen similar in general color to that of the male, but the lateral
margins of terga eight to ten yellowish brown; dorsal carina of the
tenth tergum produced into a long blunt spine, beyond the apex of
the segment; ovipositor short, brownish yellow, the. prostyles slender
and the caudal sternites of the eighth segment large and contiguous
on the meson as in auicricana, Figure 41.

Measurements

Length, $ .51 mm.

Length, 9 44 mm.

Length of abdomen, $ 41 mm.

Length of abdomen, 9 34 mm.

Length of hind wings, S 30 mm.

Length of hind wings, 9 29 mm.

Width of hind wings, 5 6-7 mm.

Width of hind wings, 9 6-7 mm.

476

There are two representatives of this species in the collection of
the Illinois State Lahoratory of Natural History, both of which were
collected at Havana, Illinois. There are also three specimens in the
Bolter Collection of the University of Illinois, which are without
locality or date labels.

H. tricolor Burmeister is a synonym of //. titia (Williamson, '12).

Family COBNAGRJONIDAE

The nymphs of this family possess flattened gills, the lateral ones
being flattened as well as the median. The median lobe of the labium
does not have a deep cleft, and tlie basal segment of the antenna is
small and does not exceed the second in length.

The adults are often brightly colored, frequently marked with
bright blue or green, but the wings are mostly clear and without smoki-
ness or tints of any kind. The antenodal cross-veins are few, never
more than two in number in Illinois species, and the postnodals are
also much reduced and fewer in number than in, the Agrionidae. The
interpleural suture is never distinct as far cephalad as the metathoracic
spiracle.*

Key to Subfamilies

NYMPHS

a. Median lobe of labium spoon-like (Fig. 10), the narrowed portion usu-
ally much longer than the expanded portion ; gills (Figs. 48-52) more

or less spatulatc, the margins nearly parallel and the tips blunt

Lestixae.

aa. Median lobe of labium not spoon-like (Figs. 11-13), the narrowed
portion not much longer than the expanded portion; gills lanceolate,
acutely i)()intcd at the tip, the margins not parallel. . Coexagrioxin'.\e.

ADULTS

a. M, arising much nearer the arculus than the nodus (Fig. 85) ; front

without pale color immediately above the clypcus Lestixae.

aa. Mj arising much nearer the nodus than the arcidu.s (Figs. 81-84,

87-90) ; front with a pale stripe immediately a^ove the elypeus

Coexagrionix.\e.

*The use of the accessory genitalia in si'ii.irating the males of closely allied
members of this family has failed to prove entirely satisfactory for such species as
Lestes forcipat ii.i and dU'junclux and the Knallagma {{""("'P composed of E. cnh-rrti.
rarunculaUim, civile, dii'npans, and doiihhdai/i. The structure of the penis in the
Enallagma group (Fijjs. 97.99,101,107.108") is so uniform that the advantage gained by
using the character is slight. It may be found that many of the.se species interbreed
— a condition already known to be true of caninculatiim and civHc — and it seems
almost certain that future investigators will unite L. forciiwtus and disjunctus
when more complete biological data are in hand.

477

Subfamily LESTINAE

The nymphs of this subfamily are long, slender insects with very
slender legs. The median lobe of the labium is much contracted at
the base, the contracted portion being usually longer than the expanded
distal portion. The lateral keels of the abdomen are frequentl}' pro-
duced at the apex into a short spinule, and the gills are long, spatulate,
and usually without heavy marginal setae and with more or less brown
pigment.

In the adults the nature of the wing venation is important. The
third median vein and the bridge unite with the R-M trunk nearer
the arculus than the nodus, and the stigma always surmounts two or
more cells. The long tibial and femoral setae, which are longer than
the distance between their bases, as well as the forcipate character of
the anal appendages of the male and the presence of a large ovipositor
with conspicuous sternites at the base of the cephalic pair of gon-
apophyses, are also important as diagnostic features.

As a rule the adults are dull in color as compared with the Coen-
agrioninae and match the color of their usual environment extremely
well.

Genus Lestes Leach

The subfamily Lestinae is represented in Illinois by a single genus,
Lestes. The nymphs of this genus are recognizable by the character
of the labium. The proximal segment of the labial palpus always has
two processes mesad of the distal palpal segment, one of them resem-
bling a fork with the median tines broken ofT, the remaining process
consisting of a long non-bifurcate projection with a short heavy hook
at the distal end and minute teeth along the mesal margins, (Fig. lo).

The adults are larger than most Coenagrioninae. Vein M,, of
both wings, always arises distad of the second postnodal cross-vein and
the stigma rarely surmounts more than three cells. The arculus is
one-third or one-fourth the length of the caudal side of the quadrangle.
The wings are commonly held horizontally when the insect is at rest.

Keys to Species

NYMPHS

a. Seeond segment of the laliinl palpus with three or four setae; labium
broad at the proximal end, the contracted portion of the median lobe
hardly longer than the expanded portion and about one-third as

broad as the latter congener.

aa. Second segment of the labial palpus with only two setae or very
rarely three (uncatus); labium narrow at the proximal end, the eon-

478

tractcd portion imich lonp;ei' than the expanded portion and less than
one-third the width of the latter.

b. Gills pointed at tip (Figs. 51,52) ; venter of abdomen without a
median row of black spots.

c. Ovipositor of female not extending eaudad of the eleventh seg-
ment; lateral gills not eonspicuously eontraeted beyond the

middle unguiculatus.

ec. Ovijxisitor of female extending eaudad of the eleventh segment ;
lateral gills conspicuously contracted beyond the middle, .uncatus.
bb. Gills not sharplj- pointed (Fig. 49) ; venter of abdomen with or
without a median row of black sjiots.

c. Lateral keels of segments 1-0 or 2-9 with long apical spines;
venter of abdomen without a median row of black spots ; gills not

conspicuously naiTowed beyond the middle vigilax.

ec. Lateral keels of segments 3-9 or 4—9 with apical spines; gills
(Fig. 49) conspicuously narrowed beyond the middle; venter of

abdomen with a median row of black spots ) jorcipniux.

I rectangularis.

ADULTS

Females

a. Dorsum of thorax green.

b. Wings flaveseent eurinus.

bb. Wings not flaveseent.

c. Occiput and postgenae pale inaequalis.

cc. Occiput and postgenae black.

d. Basal half of first abdominal segment yellow; stigma always
surmounting less than three cells; length usually about

35 mm uncatus.

dd. Basal half of first abdominal segment black; stigma usually
surmounting three or more cells: length 43—47 mm. . . .vigiJns.
aa. Dorsum of thorax black or dai'k brown, never green.

b. Metejiiinera with a black spot above and below the latero-ventral

carina congener.

bb. Metepimera without a black spot above iind below the latero-
ventral carina,
e. Occiput and postgenae pale buff or yellow ; abdomen with a

greenish tint unguiculatus.

cc. Occiput an<l postgenae black or very dark bi'own ; abdomen never

with a greenish tint.

. ( forripafus.

d. Tarsi black above ] disjunctus.

dd. Tarsi with more or less pale yellow above rectangularis.

479

Males

a. Dorsum of the thorax and usually the abdomen metallic green.

b. Inferiors more than half the length of the superiors, but never
longer than the superiors.
c. Inf ei'iors long and slender ; stigma usually surmounting three

cells vigilax.

ec. Inferiors broad and flat; stigma iisually surmounting less than

three cells uncatus.

bb. Inferiors either longer than superiors or less than half their length,
c. Inferiors less than half the length of the superiors ; wings flaves-

cent eurinus.

ee. Inferiors longer than superiors; wings not flavescent. Anaequalis.
aa. Dorsum of the thorax and abdomen black or dark brown.

b. Inferiors shorter than half the length of the superiors ; metepimera

with black spots near the latero-venti'al carina congener.

bb. Inferiors more than half the length of the superiors ; metepimera
without black spots near the latero-ventral carina,
c. Inferiors sigmoid, the apical two-thirds curved in an opposite

direction to the superiors unguiculatus.

ce. Inferiors not sigmoid, the apical two-thirds not curved in an
opposite direction to the superiors.

d. Metapleural si;ture covered with a sooty black stripe

. dinjunctus.

del. Metapleural suture not covered with a sooty black stripe.
e. Basal tooth of the mesal margin of the superior appendages

longer than the tooth of the distal third forcipatus.

ee. Basal tooth of the mesal margin of the superior appendages
shorter than the tooth of the distal third rectangularis.

Lestes congener Hagen

Nymph. — Color, pale brown or greenish.

Head twice as broad as long, the caudo-lateral angles not project-
ing strongly and provided witli few setae ; antennae long and slender ;
labium with the median lobe comparatively broad at the base, one-
third as broad as the expanded portion and about as long as the latter ;
mental setae six and sometimes a small seventli on each side, lateral
setae four or five, three or four of which are located on the distal seg-
ment; inner, mesal lobe of the proximal segment of the palpus as
broad as the fork-like process between it and the distal segment of the
palpus ; labium, when folded, extending caudad between the metacoxae.

480

Thorax slender ; the distances Ijetvveen procoxa and mesocoxa,
and between mesocoxa and the metacoxa nearly equal; front femora
about lialf the length of the hind femora and all femora with faint
preapical rings of l)rown ; wing-cases short and extending hardly
caudad of the second abdominal segment.

Abdomen with poorly developed lateral keels which are provided
with apical spines on segments 5-9; gills (Fig. 50) broad, bluntly
pointed, and provided with three conspicuous cross-bands of dark pig-
ment, the length of the median gill about four times its greatest width ;
ovipositor of the female reaching slightly beyond the apex of the tenth
segment.

Measurements

Length 16 mm.

Length of abdomen 12 mm.

Length of gills 8 mm.

Width of gills 2 mm.

Length of metathoracic wing-cases. . . 5 mm.

Length of median lobe 3 mm.

Width of median lobe 1.5 mm.

Described from three nymphs received from Dr. E. M. \\'alker
and taken at Prince Edward Island, Canada, Aug. i, 1915.

Adult ; Male. — Color, dull brown and buff or yellow.

Head i)lack, buff below ; median lobe of the labium subquadrangu-
lar, the median cleft shallow, the labial palpi broad, the distal segments
much shorter than the fixed hook, and brownish at the tips; antennae
uniform black, the first segment pale at the apex; postclypeus black
or dark brown, the anteclypeus. labrum, and genae to tlie level of the
fronto-clypeal suture yellow ; lateral ocelli w'ith small yellow spots
laterad of them; front, remainder of the vertex, occiput, except occa-
sionally a transverse yellow stripe from the occipital foramen to the
compound eyes, black.

Thorax dark brown and yellowish buff, the,prothorax dark brown,
the median lobes of the pronotum with pale lateral margins, and spots
on the meson near the caudal margin ; caudal lobe of the pronotum
black ; proepimeron black ; mesostigmal plates with pale lateral angles ;
dorsal carina usually with a pale line, the mesepisterna, except the
ventral half of the infraepisternum, black or dark brown; caudo-dorsal
angle of the metepisterna dark brown or black; metepimera with an
elongate black spot near the ventro-lateral carina and a similar spot just
ventrad of the carina ; legs striped, the coxae buff, trochanters black
above, the femora black with a narrow pale stripe including the ceph-

481

a!o-ventral row of setae, and a broad dorsal stripe, frequent!}' divided
by a faint line or row of spots; tibiae yellow, with a dark stripe includ-
ing the cephalo-ventral setae ; tai^si and claws shining black ; wings
clear, with eleven postnodals in the front wing and nine or ten in the
hind; stigma pale brown, surmounting about one and one-half to two
and one-half cells; Mo arising between the third and fourth postnodal
cross-veins in the front wing and between the second and third in the
hind wing ; paraptera brown, caudal margins black.

Abdomen black and buff ; terga i-io with broad black longitudinal
stripes, the lateral margins with broad pale stripes, the pale color ex-
tending well to the dorso-meson in the form of basal rings on segments
three to seven inclusive ; first tergum with a black spot near the latero-
ventral margin, terga three to eight with narrow apical black rings
reaching their lateral margins ; anal appendages black (Figs. 123, 124)
and reddish, the superiors compressed, the ventro-mesal margins with
large subbasal teeth and a few setae beyond these to the apical third;
inferiors shorter than the superiors, usually less than half the length
of the latter and provided with a fine brush of silken hairs; sterna 2-g,
inclusive, black, the tenth being pale and the first with a black median
spot.

Female. — Color similar to that of the male.

Head and thorax similar to those of the male.

Abdomen with interrupted basal rings on terga 3—6, inclusive,
the lateral stripes broader than those of the male ; sterna 2-7 black, one
with a black median spot and eight with a median black stripe ; anal
appendages of the usual type; superiors black; ovipositor with a black
line along the ventral margin, the margins serrate ; prostyles dark, long,
and nearly straight ; ventral margins of the ninth tergum black imme-
diately dorsad of the ovipositor.

Measurements

Length, S 34-35 mm.'

Length, 9 32-36 mm.

Length of abdomen, S 28 mm.

Length of abdomen, V 24-29 mm.

Length of hind wings, $ 19-20 mm.

Length of hind wings, 9 19-22 mm.

Width of hind wings, S 4 mm.

Width of hind wings, 9 4 mm.

This species is distinguishable from disjunctus, to which it seems
most closely related, by the metepimeral spots ; the males, by the short-
ness of the inferior appendages. The compound eyes are blue in life.

482

It appears on the wing late in summer and may be taken during
August and September.

Descril)ed from a large series of specimens in the collection of
E. B. Williamson. Probably occurs in Illinois.

Lestes disjunctus Selys

Nymph. — Not available for study.

Adult; Male. — Color, blackish brown and yellow.

Head blackish brown above, pale yellow below ; median lobe of
the labium pale, subquadrangular, the median cleft shallow, but with
the usual dark line extending to the base of the piece ; antennae black,
the two proximal segments very short, much shorter than the two distal
ones, the apex of segment two slightly paler; postclypeus almost black,
the anteclypeus, labrum, trochantins of the mandibles, and genae. yel-
lowish green; occipital and postgenal regions black, becoming pollinose
with age ; eyes brownish.

Thorax : pnjthorax black, largely pollinose in older individuals ;
proepimera and proepisterna distinct; caudal lobe of the pronotum
black, cephalic lobe black, median lobes black, the furrow separating
them indistinct; mesostigmal plates black; mesinfraepisterna black or
largelv black, the supracpisterna blackish brown with the exception
of a narrow yellow stripe on the ventro-lateral margins; mesepimera
dark brown with the exception of the cephalo-ventral shoulders, which
are vellow ; metepisterna largely yellow, becoming more or less black
with age from the spreading of the black stripe on the metapleural
suture ; stripes of the metapleural sutures covering about two-thirds of
the metepimeron, the remainder of that sclerite yellow ; postcoxal areas
buff, without black markings ; legs slender, pale, the coxae black and
pale yellow; femora striped, the hind femora with three black stripes,
the middle and front femora with two each ; tibiae with a single dark
stripe which diffuses over the segment on the distal third ; rows of setae
of the front femora composed of two and nine setae respectively;
wings clear, the antcnodal cross-veins two, po^tnodals about eleven,
and Mo arising between the second and third postnodal cross-veins in
both wings ; stigma dark brown, surmounting two cells.

Abdomen brown to black, and yellow; first tergum black with the
exception of a very narrow apical ring; dorsum of the second tergum
dark brown, the lateral margins marked by a narrow longitudinal yel-
low stripe, the dorsum of 3-6 dark brown, the stripe widened sub-
apically; segment seven black, witli a pale lateral stripe; segments
eight, nine, and ten black; anal appendages (Fig. 133) blackish brown,

483

the superiors with tuberculate lateral surfaces, the mesal margins with
two nearly equal teeth ; inferiors flat, placed horizontally, and slightly
swollen at the base and apex.

Female. — Color similar to that of the male.

Head similar to that of the male.

Thorax without the black stripe on the metapleural suture, and
the mesinfraepisternum largely pale.

Abdomen similar to that of the male except that the dorsal brown
stripes of the terga are more confined to the dorsal surface and the
lateral surfaces are mostly yellow or buff; ovipositor of the female
pale except the brown prostyles, extending caudad of the apex of seg-
ment ten; anal appendages of the usual type; dorsad of the superiors
and between them there is commonly an unpaired blunt process extend-
ing conspicuously beyond the apex of the tenth tergum.

Measiiremeyits

Length, $ 32-37 mm.

Length, 9 35 mm.

Length of abdomen, $ 25-30 mm.

Length of abdomen, 9 27 mm.

Length of hind wings, S 17-20 mm.

Length of hind wings, 9 19 mm.

"Width of hind wings, S 4-4.5 mm.

Width of hind wings, 9 4.5 mm.

There is great variation in the size of this species as well as in
its coloration. The black wash on the metapleural suture is a dis-
tinctive character of the older males, but the younger males and the
females are not easily separated from forcipatus and it is possible that
this species is a synonym of the latter. The nymphs are also reported
to be' nearly identical with forcipatus.

Not common in Illinois though occurring in certain localities prob-
ably with forcipatus and rectangtdaris.

Lestes eurinus Say •

Nymph. — Not available for study.

Adult; Male. — Color, metallic green and yellowish buff.

Head metallic green; mouth-parts buff, the median lobes of the
labium subquadrangular, with a shallow cleft and a dark line extend-
ing proximad to the base; distal segment of the labial palpus dark
brown, shorter than the fixed hook; antennae uniform dark brown, the

484

slender terminal segments long, aristiform; postclypeus black, ante-
clypeus, exposed portions of the mandibles, and genae brown or green-
ish yellow, the front, vertex, and all of the occiput and postgenae,
melallic green; eyes dark brown.

Thorax metallic green and buff; pronotum metallic green, some-
times pollinosc, the caudal and cephalic lobes becoming black with age;
pioepimeron and proepisternum distinct, black and green; mesostigmal
plates black ; dorsal carina brown, the mesosupraepisterna metallic
green; mesopleural suture brownish, the dorsal half of the mesinfra-
episterna, black; niesepimcra black (ir green, the dark color sometimes
extending ventrad onto the mctepisterna or epimera; remainder of the
metapleura and the intersternum yellow, pollinose with age; legs
striped, dark brown and buff; coxae hufi and dark brown ; middle and
hind femora with two broad, dorsal, brown or black stripes and a
narrow, dorsal, pale one, the apices of the femora dark; front femora
without the dorsal, pale, longitudinal line, the entire dorsum being dark
brown; tibiae with broad, ventral, brown stripes including the setal
rows, the tips dark ; tarsi dark brown, the claws deeply notched at the
apex, the two teeth nearly equal in length ; wings usuall}' flavescent and
with fourteen or fifteen postnodal cross-veins in the front wing and
twelve to fifteen in the hind ; JNL arising between the third and fourth
postnodals in the front wing and between the second and third in the
hind; stigma long and narrow, surmounting two and one-half to three
and one-half cells in both wings.

Abdomen metallic green and black and bufif ; dorsum of terga i-8
inclusive, green, the lateral margins of the same terga bufY, the buff
stripe becoming dark brown or black on the apices of 4-8; venter of
3-8, and all of segments nine and ten and sometimes seven and eight
black, the terminal segments pollinose with age ; anal appendages black,
the superiors long and curved, the dorso-lateral margins coarsely tuber-
culate at the apices, the meso-ventral margins with a single sharp basal
tooth, and a median projection whicli has several smaller teeth at the
apex ; inferiors blunt at the apices and each with a brush of fine setae.

Female. — Color, metallic green, and yellow and black.

Head similar to that of the male.

Thorax : prothorax similar to tliat of the male ; mesothorax witli a
very broad brownish stripe covering the dorsal carina and a green
longitudinal stripe in the middle of each mesosupraepisternum ; meso-
pleural suture with a broad brownish stripe which extends across the
dorsal portion of the infraepisternum ; metepimera with indefinite,
brown, oblique stripes.

485

Abdomen similar in general color to that of the male ; anal appen-
dages largely black or dark brown, the process immediately above and
between the superiors projecting as in disjunctus; ovipositor with
broad lateral valves, the ventral margins coarsely toothed, the distal
portion separated from the tenth segment by a considerable interval ;
more than the ventral half of the lateral valves black; eighth sternites
large, conspicuous, nearly black, and contiguous on the meson.

Measurements

Length, S 48^9 mm.

Length, 9 47 mm.

Length of abdomen, S 39 mm.

Length of abdomen, 9 36 mm.

Length of hind wings, $ 29 mm.

Length of hind wings, 9 28 mm.

Width of hind wings, S 6.5 mm.

"Width of hind wings, 9 5.5 mm.

Described from two males in the Bolter collection of the Uni-
versity of Ilhnois and a number of females in the collection of E. B.
Williamson.

The species is closely related to vigilax and inacqualis, but both
sexes may be distinguished by the flavescent wings; the males, by the
short inferior anal appendages.

Probably occurs in Illinois.

Lestes forcipatus Rambur

Nymph. — Color, buff or green.

Head brown and buff ; labium, when folded, extending just caudad
of the mesocoxae; mental setae six, the lateral setae three, two of
which are located on the distal segment of the palpus; antennae of the
usual Lestes type.

Thorax about as long as broad, brown ; legs slender, the femora
all with faint subapical rings and several rows of small setae; tibiae
with dark brown apices and with a few three-pointed subapical scales ;
tarsi with the apical half of the last segment arid the tarsal claws dark
brown; metathoracic wing-cases extending to the middle of the third
abdominal segment.

Abdomen long and slender ; lateral keels with heavy setae at the
apices on segments five to nine, and a single row of smaller ones from
the bases tp the apices of the keels of the same segments ; terga all with

486

much more pigment than the sterna, and with small setae distributed
evenly over the surfaces ; sternum of segment ten with long hair-like
setae; gills (Fig. 49) spatulate, broadest just proximad of the middle,
three or four times as long as broad ; tips rounded or obtusely pointed,
black, and two rather indistinct dark cross-bands proximad of the tip;
gills sometimes nearly black.

Measurements

Length 19-20 mm.

Length of abdomen 14 mm.

Length of gills 8.5-9 mm.

Width of gills 2-3 mm.

Length of median lobe 2.4 mm.

Width of median lobe 5-1.7 mm.

Adult; Male. — Color, dark brown and yellow.

Head brown and buff, the median lol)e of the labium pale or
nearly white, subquadrangular in outline, the median cleft shallow
and narrow but apparently extending well towards the base of the
piece ; proximal segment of the palpus pale, except the distal half of the
fixed hook which is black; antennae dark brown with a short basal
segment, a much longer second segment, and two terminal aristiform
segments which together are much longer than the two basal ones;
clypeus and laljrum pale yellow or greenish ; exposed portions of the
mandibles, their trochantins, and the genae as far dorsad as the fronto-
clvpeal suture, pale ; front and vertex brown ; occipital and postgenal
regions largely dark brown or black, becoming pollinose with age.

Thorax brown and yellow ; prothorax brown above, pale below,
the proepimera distinct, pale, with a dark dorsal border ; caudal lobe
of the notum not especially prominent or convex, the cephalic lobe
with a median circular black spot and the median lobes each with an
irregular H-shaped dark mark; cephalic portion of the prescutum tri-
angular, not deeply depressed ; stigmal plates brown and black ; pleural
sutures and the dorsal carina pale, the pale stripe of the mesopleural
suture becoming bluish with age; legs striped, yellow and black, the
coxae and trochanters entirely ])ale, the femora and tibiae striped and
the tarsi and claws entirely black ; wings with ten to eleven postnodal
cross-veins and with M, arising between the third and fourth post-
nodals in tlic front wing and between the second and third in the hind
wing.

Abdomen dark brown, often with a trace of metallic green;
sterna of segments three to nine black; dorsum of terga i-io with

487

brown longitudinal bands which are considerably narrowed basally on
segments three to seven and conspicuously widened subapically on seg-
ments 2-6, the apically widened portion enclosing a lateral yellow spot
en segments 3—6; segment nine completely black except a small lateral
yellow spot; lateral surfaces of terga 1-8 and ten, yellow; anal appen-
dages (Fig. 137) consisting of broad superiors which are coarsely
tuberculate on the lateral surfaces and have two strong, mesal teeth ;
inferiors nearly as long as the superiors, not laterally compressed, but
flattened and placed horizontally.

Female. — Color similar to that of the male.

Head and thorax not appreciably different from those of the male.

Abdomen without the yellow lateral spots of the male ; ovipositor
extending caudad of the tenth segment, the lateral valves serrate on
the apical two-thirds of the ventral margins (Fig. 114).

Measurements

Length, S 44 mm.

Length, $ 41 mm.

Length of abdomen, S 30 mm.

Length of abdomen, 9 32 mm.

Length of hind wings, S 23-24 mm.

Length of hind wings, 9 24 mm.

Width of hind wings, S 5 mm.

Width of hind wings, 9 5 mm.

One of the commonest of the Lestinae in Illinois. The nymphs
usually occur along with rectangularis in shady stagnant pools. The
species is on the wing from early June well into September, and nymphs
have been taken at Urbana late in July and at Lexington, Ky., late in
August. It seems probable that there is more than one brood of the
species per year.

The nymph is inseparable from rectangularis and there seems to
be no noticeable difference in the length of the developing ovipositor
of the female as Walker inferred there might be ('14: 197)-

The adult females are also inseparable from rectangularis except
by the (!omparatively shorter length and the black tarsal segments. As
already mentioned, the females have no important characters which
differentiate them from the species disjuncttis.

Lestes inaequaIvIS Walsh

Nymph. — Unknown.

Adult; Male. — Color, metallic gi;een and black; or bronze and
black above, yellow or bufif below.

488

Head green and yellow ; labium buff, subquadrangular, the shal-
low cleft apparently extending^ to the base of the piece; palpi broad;
antennae dull brown, the first segment much shorter tlian the second
and with a pale ring at the distal end; postclypeus metallic green or
black, the anteclypeus and labrum, except a small short black stripe
on the lateral margins, pale yellowish green ; exposed portions of the
mandibles, the genae as far dorsad as the fronto-clypeal suture, yel-
low, the remainder of the front and the vertex, metallic green; occiput
and postgenae largely yellow; compound eyes brown.

Thorax metallic green above, yellow or buff below, the pronotum
usually black, including the cephalic, median, find caudal lobes, the
proepimera black on the dorsal half, the ventral half bufi; mesosupra-
episterna metallic green, the infraepisterna black on the dorsal half, the
remainder yellow ; mesepimera metallic green except the cephalo-ven-
tral slioulder, which is yellow ; dorso-caudal angles of the metepimera
with a triangle of green, remainder of the metapleura and the inter-
sternum pale yellow ; legs striped, black and yellow ; coxae entirely buff,
trochanters, at least the middle and hind ones, with a black dorsal
stripe; middle and hind femora with three black stripes, a ventral and
two dorsal, and three yellow stripes, the front femora, however, with
two black stripes, the cephalic one including the cephalo-ventral row of
setae ; tiliiae with a single ventral l)lack stripe including the cephalo-
ventral row of setae; tarsi black, the claws long, black, and deeply bifid
at the tip ; wings clear, with sixteen postnodal cross-veins in the front
wing and thirteen to fourteen in the hind; Mo arising between the
fourth and fifth postnodals in the front wing and between the third
and fourth in the hind ; stigma surmounting from slightly less than
two to two and one-half cells.

Abdomen with the dorsum of terga i— lo dark, the basal segments
metallic green, the apical segments dull Iilack ; lateral margins of terga
1-8 pale yellow or buff, the color extending well towards the meson on
the base of segments 3-6; sterna one and ten yellow, 3-9 inclusive.,
black, shining; anal appendages long, black, the superiors pale at the
base, the meso-venlral margins with a large ba^al tooth (Figs. 131,
132) and a number of smaller ones distad of this; dorso-lateral sur-
faces of the appendages coarsely tul)erculate ; inferiors longer than the
superiors, the tips bent mesad. approximate and finely pilose; parameres
of the eighth sternum small, subquadrangular; bases of the inferiors
large and apparently fused.

Pcmalc. — Color similar to that of the male.

Head similar to that of the male.

J

489

Thorax similar to that of the male excepting that the dorsal carina
and mesopleural suture show distinct brown; legs with one dorsal
black stripe, frequently reduced to a row of spots; wings with the
stigma surmounting slightly less than three cells.

Abdomen with lateral, marginal, pale stripes on all terga, the
stripes as a rule broader than those of the male; anal appendages of
the usual type, the superiors pale, slightly darker at the tips; ovipositor
long, the lateral valves widely separated from the tenth segment at the
apex, the ventral half, or more, black; prostyles slender, bent ventrad
at the tips, and with a black dorsal stripe ; sternites of the eighth seg-
ment large, the caudo-dorsal angles acute.

Measiircmcnis

Length, $ 54 mm.

Length, 2 49 mm.

Length of abdomen, S 43 mm.

Length of abdomen, 2 38.5 mm.

Length of hind wings, S 29 mm.

Length of hind wings, 2 28 mm.

Width of hind wings, $ 6.5 mm.

Width of hind wings, 2 5.5 mm.

Described from two males and two females in the collection of
Mr. E. B. Williamson.

Not taken in Illinois by the writer, but reported by Walsh ('62)
from the vicinity of Rock Island. The species is closely related to
z'igilax, but is distinguishable from the latter by the pale occiput and
the long inferior anal appendages of the male.

Lestes rectangularis Say

Nymph. — Color, buff or pale green.

Head elliptical, the width much greater than the length ; eyes dark ;
caudo-lateral margins of the head without setae; labium extending
caudad^ between the metacoxae; mental setae six; lateral setae three,
two being on the distal segment of the palpus.

Thorax : mesothorax and metathorax much wider than the pro-
thorax; legs slender, the femora with longitudinal rows of minute
setae, the apices of all the femora fuscous and with a subapical dark
ring; tibiae with small setae arranged in rows and with fuscous apices;
tarsi with the apical half of the third segment and the claws dark
brown, the hind tarsi with a very long apical segment and a very short
proximal one.

490

Abdomen : cuticle provided with minute setae and somewhat
heavily pigmented with bromi ; lateral keels with heavy apical setae on
segments 5-9 and with about nine smaller setae along the keels to their
bases ; sterna with a double row of median spots, two to each segment ;
segment ten hairy beneath; gills similar to those of forcipatus, with
a row of short setae on both margins, the extreme tips being usually
free; the portions of the eleventh segment proximad of the lateral gills
bear five or six small setae on the ventral surface ; the pigmentation
of the gills is usually brownish, though frequently black, but the gill
is not as a rule as black as the gill of forcipatus; female ovipositor ex-
tending to the apex of the tenth abdominal segment.

Measurements

Length 22 mm.

Length of abdomen 17 mm.

Length of gills 9.5 mm.

Width of gills 2.3 mm.

Length of median lobe 4 mm.

Width of median lobe 5-2.0 mm.

Adult; Male. — Color, dark lirown to black, and sulphur-yellow.

Head brown and yellow ; labium pale, the median lobe subquad-
rangular, with a shallow cleft and darker stripe extending proximad
to the base; palpi rather short; antennae entirely brown, the first seg-
ment much shorter than the second, and the third and fourth much
longer than the first two together ; postclypeus dark brown, shining,
the anteclypeus, labrum, exposed portions of the mandibles, their
trochantins, and the genae, shining yellow; front and vertex, dull
brown, nearly black, the preocellar furrow very deep and extending
laterad nearly to the bases of the antennae ; occiput and postgenae black,
pollinose with age.

Thorax brown and yellowish ; pronotum yellowish buff, the ce-
phalic lobe with a large median lirown spot, the median lobes each with
an irregular H-shaped mark which covers a large portion of the lobe
in the older specimens; caudal lobe blackish brown, the caudo-lateral
margins pale ; supraepisterna of the mesothorax with a broad, brown,
longitudinal stripe from cephalic to caudal margins, covering about
three-fourths of the sclerites, the lateral margins of the stripe irregular ;
mesopleural suture covered by a broad yellow stripe which is widest
cephalad, narrowed near the wing bases, and becomes bluish with age;
mesepimera with longitudinal median brown stripes extending from
near the caudal margin to the cephalic shoulder, widened considerably

491

caudad and in contact with the mesopleural suture adjacent to the wing
bases, narrowed cephalad, and coming to a rather abrupt end on the
cephalic shoulder; margins of the stripe irregular; metepisterna pale
yellow with a triangular brown spot on the caudo-dorsal angle; re-
mainder of the pleura and the intersternum pale yellow or buff; legs
buff and black or dark brown, the coxae and trochanters pale, the
femora with two brown stripes each, a cephalo-dorsal one and a ventral
one between the rows of setae ; tibiae with a single, cephalo-ventral
brown stripe including the cephalic row of setae ; tarsi and claws brown,
the dorsum of the tarsal segments usually more or less yellow; wings
with eleven to twelve postnodal cross-veins, Mo arising between the
third and fourth postnodals in the front wing and between the second
and third in the hind wing ; stigma surmounting slightly more than two
cells in both wings.

Abdomen brown and yellowish, long and slender ; terga one and
two brown on the dorsum, pale on the sides, the stripe on two con-
tracted near the middle ; terga 3-7 with yellow lateral margins, nar-
row interrupted basal rings and longitudinal brown stripes on terga
eight and ten, and a triangular, lateral, apical, spot on nine ; anal ap-
pendages (Fig. 128) brown or blackish, the superiors mostly smooth
and not coarselv tuberculate on the lateral surfaces, the basal, mesal
tooth small, and much smaller than the tooth at the distal third of each
superior; inferiors more than half the length of the superiors, black,
the tips laterally compressed.

Female. — Color the same as that of the male.

Head and thorax not appreciably different from those of the male,
with the exception of the slightly wider pale stripes on the mesopleural
suture.

Abdomen shorter than that of the male; anal appendages of the
usual type (Fig. 115) ; ovipositor extending as far caudad as the apices
of the anal appendages or beyond, the lateral valves broad, and with
serrated ventral margins, the ventral half being usually black.

Measurements

Length, $ '50-52 mm.

Length, 9 46.5 mm.

Length of abdomen, S 33^2 mm.

Length of abdomen, 9 31-34.5 mm.

Length of hind wings, $ 18.5-24 mm.

Length of hind wings, 9 20-23 mm.

Width of hind wings, 5 5 mm.

Width of hind wings, 9 5 mm.

492

This species occurs in the same localities in which forcipatus is

found. Nynijihs taken at Urbana emerged as early as May 29 and as
late as Jul\- 17, the species ha\ing a considerable range in the ])eriod
of emergence. There is a possibility that this species has a two-
brooded life cycle.

Specimens have been seen from Urbana, Galena, Lake Villa, Ore-
gon, Savanna, and McHenry County.

Lestes uncatus Kirby

Nymph. — Color, buff or green.

Head broad, the caudo-lateral margins not projecting and with-
out heavy setae; antennae of the usual Lestes type; mental setae six
or seven on each side; lateral seta three, two of which are located on
the distal segment ; marginal setae of the mentum extending to the base
of the expanded portion of the median lolje; labium, when folded, ex-
tending caudad of the metacoxae.

Thorax : legs very long and slender, the apices of the femora
and the apices of the tibiae and the distal half of the third tarsal seg-
ments brown; wing-cases extending to the middle of the fourth ab-
dominal segment.

Abdomen with well-developed lateral keels wliicl: are provided
with short spines on the apices of segments 5-Q; cuticle uniform in
color, the dorsum of segments nine and ten and the venter of segment
ten with long, fine, silken hairs ; ovipositor of the female long and ex-
tending lieyond the apex of tlie eleventh segment ; gills conspicuously
contracted beyond the middle as in rcctaiu/iilaris and forcipatus, ratlier
sharply pointed at the ajjcx, the point similar to that of nngiiicuhitus.

Measurements

Length 18 mm.

■Length of abdomen 11 mm.

Length of gills 8 mm.

Width of gills 2 mm.

Length of median lobe 5.5 mm.

Width of median lobe 3-1.6 mm.

Described from a single specimen collected by Dr. Edna Mosher
in July, 191 5, at Orono, Maine.

Adult; Male. — Color, metallic green and pale yellow.

Head dark green above, pale below; occiput black, the median
lobe of the labium pale and subquadrangular with a typical cleft;

493

palpiger short and indistinct; fixed hook of the proximal segment
longer than the distal segment, black at the tip ; antennae black, the
second segment pale at the distal end ; postclypeus black ; the ante-
clypeus, labrum, exposed portions of the mandibles, their trochantins
and the genae, pale yellow ; front, vertex, clypeus, and labrum thinly
pilose, the setae pale ; eyes pale yellow.

Thorax metallic green, black, and yellow ; pronotimi green, the
caudal lobe narrow, the median lobes not distinctly separated, pro-
epimeron and proepisternum black, pollinose with age, the suture be-
tween the epimeron and notum indistinct ; dorsal carina of the meso-
thorax black; mesosupraepisternum green, the mesinfraepisternum and
the mesopleural suture black ; mesepisternum green with the exception
of the cephalo-ventral shoulders ; metapleural suture usually black, the
stripe indefinite, increasing in extent with age and covering a large por-
tion of the metepimera ; postcoxal areas bufl: ; legs black and buff, the
coxae pale and black, femora with three black stripes alternating with
three bufif-colored ones; tibiae, tarsi and claws black; setal rows of
the front femora composed of two and nine setae respectively; wings
clear, the antenodal cross-veins two in number, postnodal cross-veins
ten to eleven ; stigma of the front wing surmounting two cells ; stigma
of the hind wing slightly smaller than that of the front wing; Mo
originating between the third and fourth postnodal cross-veins in the
front wing and between the second and third in the hind wing.

Abdomen metallic green; first tergum green on the dorsum and
with a small, black, lateral basal spot on each side ; dorsum of the sec-
ond tergum green, the green extending well onto the sides, the latero-
ventral margins, however, being pale ; terga 3-7 with broad, longitu-
dinal green stripes, widened subapically, and with narrow basal, dor-
sally interrupted, yellow rings and longitudinal lateral stripes; all of
segments eight, nine, and ten green above, black or pollinose below;
sternum of segment one with a median black spot at the caudal end,
3-10 black ; superior anal appendages (Figs. 135, 136) black at the tip,
brownish at the base, the lateral surfaces tuberculate, the mesal mar-
gins with a large basal tooth and a row of small ones beyond to the
distal third ; inferiors broad, black and distinctly expanded at the apex.

Female. — Color, metallic green and yellow.

Head similar to that of the male.

Thorax with pale dorsal carina and mesopleural sutures, and
usually lacking the black stripe on the metapleural suture.

Abdomen : proximal half of the first tergum with a pale dorsum ;
terga 8-10 with broad lateral stripes of yellow ; first sternum without
the black spot and the eighth, instead of being all black, has a mesal

494

stripe ; superior anal appendages black at the tips, slightly longer than
the inferiors; ovipositor with the lateral valves black on the ventral
half, the apex extending well caudad of the tenth segment; prostyles
black at the tip and on the dorsal surfaces, the tips extending beyond
the apices of the anal appendages.

Measurements

Length, $ 34 mm.

Length, 9 39 mm.

Length of abdomen, S 26-28 mm.

Length of abdomen, 9 29 mm.

Length of hind wings, S 21 mm.

Length of hind wings, 9 23 mm.

Width of hind wings, S 4.5 mm.

"Width of hind wings, 9 4.5 mm.

A moderately common species though not as common as either
rcctangularis or forcipatus. Taken at Oregon July i, 191 5, at Free-
port July 8, and at Urbana.

Lestes unguiculatus Hagen

Nymph. — Color, light brown or green.

Head about twice as broad as long, subelliptical, the caudo-lateral
angles not projecting, and provided w'ith a few weak setae; antennae
slender, entirely pale, the third segment longest, segment two longer
than one; labium slender, and extending caudad of the mesocoxae;
mental setae seven, lateral setae three, two of which are located on the
distal segment of the palpus; lateral marginal setae of the mentum
about twelve, the row extending from the articulation of the palpus to
the base of the expanded portion.

Thorax slender, much contracted behind tlie liead, about as broad
as long; legs slender, the femora with rows of short setae and faint
preapical rings of brown; til)iae with rows of setae, the apices brown;
tarsi pale except the apical half of the third segment which is brown;
metathoracic wing-cases extending caudad to the middle of the third
abdominal segment.

Abdomen long and slender, the lateral keels moderately well de-
veloped and possessing spines at the apices of segments 5—9; venter
of the abdomen usually much paler than the dorsum though sometimes
with faint median stripe and stripes just ventrad of the lateral keels;
caudo-lateral angles of terga 1-8 sometimes with darker spots; gills

495

widest near the base, and gradually tapering to a point at the apex, not
conspicuously contracted beyond the middle (Figs. 51, 52).

Measurements

Length 19 mm.

Length of abdomen 14 mm.

Length of gills 9 mm.

Width of gills 1.5 mm.

Length of median lobe 2 mm.

Width of median lobe 5-1.5 mm.

Adult; Male. — Color, dull brown or metallic green and yellow.

Head metallic green and brown, often more or less bronze; me-
dian lobe of the labium subquadrangular, with the usual cleft; prox-
imal segment of the antennae with pale spot at the distal end, the re-
maining segments dark ; postclypeus dull metallic brown, the anteclyp-
eus, labrum, and the exposed portions of the mandibles, their
trochantins, and the genae, shining yellow ; eyes slate-gray ; occipital
and postgenal regions wholly yellow.

Thorax dull brown and yellow ; caudal margin of the pronotum
entire, the caudal lobe narrow and not convex; cephalic lobe much
longer and possessing a median, circular, black spot; median lobes with
irregular H-shaped black or dark marks, one to each lobe ; proepimeron
distinct, pale brown, black on the dorsal margin; mesosupraepisterna
dull metallic brown, sometimes greenish, with the lateral fourth yellow ;
mesopleural suture with a broad yellow stripe; mesepimeron almost
entirely brown, with the exception of the cephalic shoulder; mesinfra-
episternum with the dorsal half brown or greenish in older specimens
and with a median spot in younger individuals, the remainder of the
sclerite pale ; metepisterna with triangular brown spots adjacent to the
wing, bases; metapleural suture and the metepimera pale buff; post-
coxal areas pale yellow, without dark spots ; paraptera crescentic, the
caudal margins faintly emarginate; legs striped, the coxae and the
trochanters buff, the femora pale yellow with two black or dark brown
stripes ;, tibiae with a single brown stripe including one of the two rows
of setae ; tarsi and claws black ; front femoral rows of setae containing
three and eight setae respectively ; wings clear, the postnodal cross-veins
about eleven, and Mo originating between the second and third in the
front wing and between the first and second, usually near the second,
in the hind wing.

Abdomen mostly yellow in recently emerged specimens, dark me-
tallic green or brown in older ones ; dorsum of the first tergum brown

496

on the caudal half; tcrga 2—10 all with hrown, dorsal, longitudinal
bands, extending from the cephalic nearly to the caudal margins, the
bands being slightly enlarged at the caudal ends; terga 2-10 with nar-
row rings of I)rown on the caudal margins; sterna 3—8 black; nine and
ten, pale; anal appendages (Figs. 125, 126) consisting of strong su-
periors, coarsely tuberculate on the lateral surfaces and hairy at the
apices, the mesal margins possessing a large basal tooth and a number
of smaller ones beyond this to about the distal third; inferior appen-
dages sigmoid, the distal two-thirds curved in an opposite direction to
the superiors.

Female. — Color similar to tliat of the male.

Head ami thorax identical with those of the male.

Abdomen similar to that of the male with the exception of the
dorsa of the cephalic terga, which are as a rule i)aler in color, and
terga nine and ten, which possess a mesal dark line; ovipositor reach-
ing apex of tenth segment, the lateral \alves black Ixdow, the ventral
margins serrate or coarsely toothed.

Measurements

Length, $ 39 mm.

Length, 9 35 mm.

Length of abdoiiipn, $ 27 mm.

licngth of ahdomcn. 9 27 mm.

Length of liind wings, S 21 mm.

Length of hind wings, 9 22 mm.

Width of hind wings, S 5 mm.

Width of hind wings. 9 T) mm.

A very conmion species at Urbana, occurring in abundance in
pools north of town. The nymph is easily separated from rcctatigu-
hiris and forcipatus Iiy means of the shape of the gills. The adult is
also easily separated from rcctanyidaris and forcipatus and seems to
be most closely related to nncatits, from which species it differs mainly
in color though also in the shape of the anal appendages of the male and
the length of the ovipositor of the female. The nymph is more closely
related to uiicatiis than to any other species.

The species has a wide distribution in Illinois and flies from early
June to August.

Lestes vir,ii,.\x Hagen

jYyiiiph. — Color, light brown or green.

Head broad, about twice as broad as long, the caudo-lateral angle
not projecting and without setae ; antennae slender and of the usual

497

Lestes type ; labium very slender and when folded extending caudad
about to the metacoxae ; mental setae five or six ; lateral setae three,
two of which are located on the distal segment of the palpus ; marginal
mental spinules apparently wanting or few in number and not extend-
ing proximad to the base of the expanded portion ; the teeth of the
mesal margins of the mesal lobe of the proximal segment of the palpi
are large and square and the furrow representing the median cleft of
the median lobe is conspicuous and extends proximad one-third the
length of the expanded portion.

Thorax slender ; legs very slender, the femora and tibiae with
rows of short setae ; femora with subapical rings of brown, the -tips
of the tibiae and the distal half of the third tarsal segment also dark
brown ; wing-cases extending about to the middle of the third abdom-
inal segment; lateral keels with strong apical spines on segments 1-9
inclusive, the seta at the apex of nine especially long; gills (Fig. 48)
very long and slender and of about equal width throughout, the apices
bluntly pointed ; ovipositor of the female nearly reaching the apex of
segment ten.

Measuremenis

Length 21-30 mm.

Length of abdomen 17-22 mm.

Length of gills 13 mm.

Width of gills 1.25-1.75 mm.

Length of median lobe 3.3-4 mm.

Width of median lobe 1.5-2 mm.

The nymph is the longest of any species of Lestes. It is easily
recognizable by the slender gills (Fig. 48) and the apical setae of the
lateral keels.

Described from a single exuvium obtained from Dr. E. RL
Walker and several specimens in the collection of the Illinois State
Laboratory of Natural History from Grass Lake and Havana, III. ;
dates of collection of the specimens from Grass Lake June 23, 24, 1892.

Adult; Male. — Color, dull metallic green and buff.

Hekd dull greenish black or black ; median I'obe of the labium sub-
quadrangular, the median cleft shallow; fixed hook of the palpus black
at the apex; antennae black, the tip of the first segment slightly pale,
the second segment twice as long as the first ; postclypeus black, the
anteclypeus brown ; labrum pale green ; exposed portions of the mandi-
bles, their trochantins. and the genae, pale brown ; front and vertex
metallic green.

498

Thorax metallic green, prothorax largely black, becoming polli-
nose with age ; suture between pronotum and the proepimeron indis-
tinct ; caudal lobe of the notum much narrower than the cephalic lobe
and considerably widened on the meson; furrow separating the median
lobes obscure; cephalic portion of the prescutum small, triangular, and
little depressed ; mesosupraepistcrna and mesepimera green, the meso-
pleural suture and the dorsal carina with pale lines which become dark
with age ; mcsinfraepisternum black, the metapimcra, nictepisterna
and intersternum pale at first but black or pollinose with age; legs buff
and black; coxae pale and black, femora almost entirely black, with
a narrow pale stripe between the setal rows on the ventral surface, and
a short stripe on the dorsal surface of the hind femora ; rows of front
femoral setae consisting of two and eight setae respectively ; tibiae and
tarsi black; wings clear, the antenodal cross-veins two, postnodals fif-
teen to seventeen in the front wings and twelve to thirteen in the hind
wings; RL arising I)etwcen the fourth and fifth postnodal cross-veins in
the front wings and between the third and fourth in the hind wings ;
stigma usually surmounting three cells, light brown or nearly white in
color.

Abdomen metallic green and black ; terga i— 6 with narrow lateral
stripes, 7-10 black; sterna of all segments black, the first sometimes
light, but black in older specimens ; superior anal appendages black, the
lateral surfaces tulierculate and the mesal margins with a basal hook
and two indentations Iietween this and the apical third; inferiors long
and slender, not dilated at the apex (Figs. 129, 130).
» Female. — Color, metallic green and black.

Head and thorax similar to those of the male.

.■\bdomen long and very slender, the dorsum of terga i-io and
apical rings on all terga e.xcept the two caudal ones dull brown or
greenish; sterna 2-8 mostly black, ovipositor long and slender, the
prostyles long and the eighth sternitcs at the base of the cephalic pair
of gonapophyses with a long dorso-caudal projection.

Mcnxnremrnts

Lenfrth. S 43^7 mm.

Length, 9 43^5 mm.

Length of ahdoinon. S 34—38 mm.

Length of abdomen. 9 34—36 mm.

Length of hind wings. S 21-25 mm.

Length of hind wings, 9 26-27 mm.

Width of hind wings, S 5 mm.

Width of hind wings, 9 6 mm.

499

Males possessed by the Illinois State Laboratory of Natviral His-
tory were collected at Cedar Lake, 111., — Lake Villa — August 3, 1887.
The female was described from material obtained from Mr. E. B.
Williamson.

The species has not been seen as far south as Urbana.

Subfamily COENAGRIONINAE

The nymphs have short labia, gradually contracted proximad and
not at all spoon-like. The gills are more or less lanceolate, acutely
pointed at the tip, and the smaller tracheae are commonly well devel-
oped, pigmented, and visible to the naked eye. The abdomen is short
in proportion to its diameter.

The adults are distinguished from the Lestinae by means of the
wing venation. Mo arising nearer the nodus than the arculus. The
femoral and tibial setae are much shorter than those of the Lestinae
and the coloration of the body is frecjuently bright, the yellows, blues,
and reds being often conspicuous. The anal appendages of the male
are short and the eighth sternites at the base of the cephalic pair of
gonapophyses of the female are reduced to small triangles or are want-
ing.

Key to Genera

NYMPHS

a. Gills half as broad as long (Figs. 58, 63, 67, 68) ; labium without
mental setae ; proximal segment of the labial palpus with two similar

fixed hooks ' Argia.

aa. Gills not more than one-third as broad as long ; labium provided

with mental setae ; proximal segment of the palpus with a single,

sharp, fixed hook, and a truncate process with teeth at the apex.

b. Caudo-lateral angles of the head projecting and forming a blunt

tubercle, the margins of the head much contracted between the

tubercles and the eyes.

c. Gills (Fig. 59) without cuticular pigment, one-third as broad
as long, the margins thickly provided with setae which extend

from the base to the apex of the gills AvipMagrion.

ee. Gills with euticiilar pigment, not more than one-sixth as broad

as long, the margins sparsely setose CJiromagrion.

bb. Caudo-lateral angles of the head not projecting and forming a
blunt tubercle, the margins of the head not contracted between the
tubercles and the eyes.

c. Gills with the tracheal branches much more numerous at the
widest portion of the gill N elialennia.

500

cc. Gills with the tracheal branches equally distributed throughout
the length of the gill.

d. Gills with long, tapering points, the cuticular pigment, if
present, always in cross-bands; mental setae of the labium
usually four.

e. Gills without cuticular ])igniont (Fig. 60) ; lateral keels with-
out setae; nymphs of small size, full-grown individuals

I'arely more than 14 mm. in length including gills

Anomalagrion.

ee. Gills usually wdth cuticular pigment in the form of arcuate
cross-bands ; lateral keels with several rows of small setae ;
nymphs larger, when full-grown 18-20 mm. in length in-
cluding gills Isclinura.

dd. Gills with blunt points (Figs. 56, 57, 70-72, 75-77a, 80), or
if with long points, then with cuticular pigment other than in
cross-bands: mental setae usually three (four in E. calverti
and E. cyathigerum) Enallagma.

ADULTS

a. Cephalic row of setae of all tibiae twice as long as the .spaces between
their bases; postnodal cross-veins of the front wings twelve or more
in number; JI. arising between postnodal cross-veins five and nine

in the front wing Argia.

aa. Cephalic row of setae of all tibiae less than twice as long as the
spaces between their bases ; po.stnodal cross- veins of the front ■\vings
usually less than twelve in number; ^lo arising between the third and
fifth, rarely sixth, postnodal cross-veins in the front wing,
b. Dorsum of the thorax metallic green or bronze ; female pronotum

with the caudal lobe trilobed Xekalennia.

bb. Dorsum of the thorax not metallic green or bronze; female pro-
notum not with the caudal lobe trilobed.

c. Postocular spots wanting ; mesopleural suture without a distinct

black stripe, the stripe not wider than the suture itself.

d. Dorsum of abdominal terga 1-6 reddi.sh or bulif : width of the

stigma measured between costa and Sc.-1-;R, much greater than

its length ; female with a heavy spine on the caudal margin of

the eighth sternum Amphiagrion.

dd. Dorsum of abdominal terga 1-6. black ; width of the stigma
mea.sured Ijetwcen costa and Sc^+R, not greater than its length ;
female without a heavy spine on the caudal margin of the

eighth sternum Chromagrion.

ee. Postocular spots present ; mesopleural suture usually with a dis-
tinct black stripe, the stripe wider than the suture itself.

501

d. Mo arising between the fourth and sixth postnodal cross-veins
in the front wing and between the third and fourth in the

hind • • .Enallagma.

dd. M„ arising between the third and fourth postnodal cross-veins

in the front wing and between the second and third in the hind.

e. Dorsum of the fourth abdominal tergum black, except a

narrow basal ring; stigma of the front wing of the male

not remote from the margin Isclinura.

ee. Dorsum of the fourth abdominal tergum orange or yellow
with the exception of a basal and apical spot in the male
and a small apical spot in the female; stigma of the front

wing of the male remote from the margin (Fig. 83)

Anomalagrion.

Genus Argi.\ Rambur

The nymphs are characterized by the short thickset form, the
abdomen being as a rule much shorter than that of closely allied genera.
The labium is broad at the proximal end of the median lobe and the
median process of the proximal palpal segment consists of a simple
hook similar to the mesal hook of the same segment. The gills are broad
and oval to elliptical in outline, are heavily pigmented, and the legs
are long and slender, with a number of dark brown rings on the fem-
ora and tibiae. The body is dark in color for the most part, and the
species live either in the mud on the bottom of sluggish streams or
under rocks or debris in the swifter currents.

The adults are distinguishable from other genera by the dorsal
carinae of the femora and the long setae of the front tibiae ; by the
point of origin of vein Mo, which is always beyond the fifth postnodal
cross-vein, and by the number of postnodal cross-veins of the front
wing, the latter ranging from twelve to seventeen in number. The
parameres of the ninth sternum of the male extend caudad to the apex
of the segment, and the sternites at the base of the cephalic pair of
gonapophyses are distinct and subtriangular.

Key to Species

NYMPHS

a. Labial palpi with a single weak seta on the proximal segment ; gills
broad at the tip (Fig. 58), the margins parallel for a considerable
distance, and without light cross-bands and not coarsely spotted

with dark pigment moesta putrida.

aa. Labial palpi with two or more setae on the proximal segment ; gills
tapering to a point, the margins not parallel or parallel for only a

502

short distance (Figs. 63, 67, 68), and frequently wth one or more

light cross-bands and coarselj' spotted with dark pigment.

b. Gills broadest beyond the middle, decidedlj^ ovate (Fig. 63) and

frequently with a V-shaped cross-band near the apex ; median lobe

projecting between and distad of the articulations of the labial

palpi much less than one-third the length of the proximal segment

of the palpi (Fig. 11) violacea.

bb. Gills broadest at middle, elliptical (Figs. 67, 68) and never with
a V-shaped mark near the ai)iees ; median lobe of the labium pro-
jecting between and distad of the articulations of the labial palpi

one-third or more of the length of the latter J apicalis.

1 tibialis.

ADULTS

Females

a. Wings smoky fumipennis.

aa. Wings not smoky.

b. Stigma surmounting more than one cell in the hind wing; mes-
epimora without a broad dark stripe on each, ventrad of the mes-
opleural suture ; mesostigmal plates (Fig. 154) with a sharp median

projection on the caudal margin moesta putrida.

bb. Stigma surmounting a single cell or less in the hind wing; mes-
epimera with or without (apicalis) a broad dark stripe on each,
ventrad of the mesoplcural suture; mesostigmal plates without a
sharp median projection on the caudal margins,
c. Front, vertex, and occiput wholly brown ; caudal margins of the
mesostigmal plates forming a thin blade which projects dorsad. . .

sedula.

cc. Front, vertex, and occipiit with more or less black pigment ;
caudal margins of the mesostigmal plates not forming a thin
blade which projects dorsad.

d. Black stripe of the mesoplcural suture extending more than
half-way to the wing bases from the infracpisternum.
e. Caudal margins of the mesostigmal plates (Fig. 140) not pro-
jecting caudad at the caudo-mcsal angles ; terga 1-5 of the
abdomen with the mesal pale line narrower than the black

lines on either side tibialis.

ee. Caudal margins of the mesostigmal plates projecting caudad
at the caudo-mesal angles and forming a i-ounded lobe (Fig.
142) ; terga 1-5 with the pale mesal stripe much broader

than the black stripe on either side violacea.

dd. Black stripe of the mesoplcural suture extending less than half-
way to the wing bases from the infracpisternum apicalis.

503

Males

a. Wings smokj' fumipennis.

aa. Wings not smolrv.

b. Stigma surmounting more than one cell in both wings ; abdominal

terga 8-10 black with dorsal spots of brown, or entirely black

moesfa pufrida.

bb. Stigma surmounting one cell or less ; terga 8-10 inclusive or nine
and ten. blue, never black except the eighth, and never with brown
markings.

e. Terga nine and ten blue sedula.

ce. Terga eight, nine, and ten blue.

d. Black stripe of the mesopleural suture extending from the
mesinfraepisternum to the wing bases.
6. Terga 1-5 with the pale color of the dorsum limited to a

very narrow mesal line and narrow basal rings tibialis.

ee. Terga 1-5 with the pale color of the dorsum occupying the

greater portion of the segments, the black confined to small,

' apical, lateral spots on 1— i and an apical ring in addition on

the fifth violacea.

dd. Black stripe of the mesopleural suture extending much less
than half-way from the mesinf raepistexmum to the wing bases . .
apicalis.

Argia apicalis (Say)

Nymph. — Color, dark brown.

Head one-third wider than long, pentagonal, the caudo-lateral
angles strongly projecting and armed with heavy setae; eyes black;
antennae dark brown except the first and the last two or three seg-
ments; labium very broad, the median lobe dark in color, without
mental setae but with about twelve marginal setae ; labial palpi with
three or four setae on tlie proximal segment and witli a long movable
distal segment much longer than the fixed hooks ; labium, when folded,
extending caudad of the procoxae, but not reaching the mesocoxae.

Thorax dark in color ; legs conspicuously banded, the dark por-
tions consisting of the second segment of the trochanters, two broad
bands on each femur and three on each tibia, the proximal one on
the tibiae being narrow, the next one slightly broader and located
alwut the middle, and the third nearly equal in width to the median
band and covering the apex ; tarsi of the usual form, dark brown in
color ; wing-cases extending caudad to the middle of the fifth abdominal
segment.

504

Abdomen half as broad as long, dark brown in color, tlie dorsum
with a pale median stri])e which widens noticeably on segments eight,
nine, and ten; gills (Fig. 67) elliptical, smoky, frequently possessing
one or two pale transverse bands and usually with a number of
coarse spots of pigment ; apices of the gills bluntly pointed, the margins
hairy, but without heavy setae; ovipositor of the female extending to
the apex of segment ten.

Measurements

Length 14 mm.

Length of abdomen 8 mm.

Length of gills 6 mm.

Width of gills 3 mm.

Length of metathoraeic wing-cases. . .4..5 mm.

Length of median lobe 3 mm.

Width of median lobe 1-2 mm

Adult; Male. — Color, light blue (light amparo blue), or bufif
(warm buff) and black.

Head : exposed portions of tlie mouth-parts buff or light blue,
the median lobe of the labium subtriangular, the cleft shallow and
obtuse at the proximal end; proximal segment of the labial palpus
about three times as long as the distal segment ; fi.xed hook only
slightlv longer than the distal segment, black; distal segment black;
antennae black with the exception of the first segment which has a
pale lateral stripe ; clypeus and labrum. genal region, exposed portions
of the mandil)les, and the front dorsatl t(i tlie level of the lateral ocelli,
blue; vertex black; ocellar area black, the latter sending a black line
ventrad to each antenna ; postocular spots present, circular, blue or
brown ; occiput and postgenae yellow with the exception of small black
spots on the postgenae, near the ventral margins of the compound
eyes.

Thorax light blue or buff, black, and sulphur yellow ; prothorax
black and blue ; caudal lobe of the pronotum l)lack. median lobes with
circular blue spots; noto-epimeral suture indistinct; proepimera blue
or buff, the dorsal margins black ; mesopleura and metapleura blue
or olive-buff, and without black markings except a short stripe covering
the dorsal half of the mesinfraepisternum. which extends caudad on
the mesepimeron for about one-fifth of the length of that sclerite;
postcoxal areas buff or yellow ; legs striped with black and yellow, a
stripe on each side of the femoral carinae and one on each tibia en-
closing the cephalo-ventral row of setae; tarsi black, the second and

505

third segments frequently yellow above; wings with twelve to four-
teen postnodal cross-veins, the stigma surmounting a single cell or
less, and Ma arising between the seventh and eighth, or eighth and
ninth, postnodal cross-veins in the front wing and between the sixth
and seventh in the hind wing.

Abdomen blue or buff and black, the black placed as follows —
a spot on the first tergum, longitudinal dorsal stripes on 1—7 which
extend well onto the lateral surfaces of terga 3-7 at their apices, and
the lateral margins of terga 8—10 inclusive; the yellow or blue forms
lateral stripes of pale color on terga 1—7, narrow basal rings on 3—7
inclusive, and narrow apical ring on one ; dorsum of terga 8—10 blue ;
anal appendages (Figs. 151, 152) consisting of short black superiors
and longer bifurcate inferiors, the dorsal emargination of the tenth
tergum about one-third the length of the segment; sterna 2-10 black,
one, pale buff.

Fcvialc. — Color similar to that of the male.

Head : cephalic aspect entirely blue or buff with the exception of
black spots ventrad and dorsad of the lateral ocelli and black rings
around the postocular spots.

Thorax as in the male, though usually somewhat lighter in color ;
mesostigmal plates as shown in Figure 153 with a very small caudal
projection near the caudo-mesal angles; caudal lobe of the pronotum
with more or less blue or buff and the mesopleural dark stripes of the
inf raepisternum and epimeron paler than those of the male.

Abdomen with the dorsum of the eighth and ninth terga black
with a dorsal yellow stripe and with dark brown or yellow on the
lateral surfaces; tenth tergum dark brown above, paler on the sides,
the dorsal, median emargination extending nearly to the base of the
segment; anal appendages of the usual form and pale in color; ovi-
positor with light brown lateral valves, the prostyles darker.

Measurements

Length, $ 38 mm.

Length, 2 36 mm.

Length of abdomen, $ 30 mm.

Length of abdomen, 9 '.28 mm.

Length of hind wings, $ 24 mm.

Length of hind wings, 9 23 mm.

Width of hind wings, $ 5.5 mm.

Width of hind wings, 9 5.5 mm.

A common species along all large-sized streams in Illinois. The
nymphs live in the mud at the bottom, but when mature approach the

506

banks and hide among dead submerged weeds or rubbish. The eggs
are deposited below the water on driftwood, and large numbers of
females may sometimes be seen congregated alx)ut an old log at the
•water's edge depositing eggs.

Argia fumipEnnis (Burmeister)

Nymph. — Unknown.

Adult; Male. — Color, dull brown and black.

Head : dark brown and black ; median lobe of the labium buff,
subtriangular ; antennae brown, the first segment nearly globular, the
second segment al)()ut twice as long as the first ; clypeus, labrum, ex-
posed portions of the mandibles and their trochantins, genae, and the
front dorsad of the clypeus to the median ocellus, dark brown or buff;
vertex with a transverse l)lack sjtripe which includes the ocellar area;
there is, however, a large brown spot ventrad of each lateral ocellus and
a narrow median stripe between them ; postocular spots large, con-
tiguous with the margins of the comiX)und eyes and connected by
means of a broad stripe caudad of the ocelli ; occiput and postgenae
buff; compound eyes brown.

Thorax dark brown, liiack. and huff: pronotum dark, the cei:)halic
lobe buff, the median lolies willi large, pale, lateral spots; caudal lobe
dark, with a paler spot on eacli lateral angle; proepimeron and pro-
epistenunn of the propleura not distinct, brown in color, the dorsal
border darker ; dorsal carina of the mesothorax covered by a broad
black stripe which also covers about half of each mesosujiraepisternum ;
mesepimera with a broad dark stripe ventrad of the mesopleural suture,
the stripe extending cephalad across the infraepisterna and forking
about half-way from the infraepisternum to the wing bases; margins
of the paraptera dark l)rriwn, tlie remainder buff'; metapleural suture
with a tlark line; remiiindcr of the mes(>- and metai)leura and the
postcoxal areas buff; femora each with a broad dark brown or blackish
line, the remainder buff: tibiae pale buff above, darker below, the dark
brown color including the cephaln-vcntral row of setae; wings dis-
tinctly tinged with brown; postnodal cross-veiqs sixteen in the front
wing and fifteen in the hind; AT. arising between the seventh and
eighth postnodal cross-veins in the front wing and between the sixth
and seventh in the hind wing; stigma surmounting a single cell or less.

Abdomen dark I)rown; dorsum of terga 1-7 dark brown, the
lateral margins paler in color; narrow basal rings on the cephalic
margins of terga 3—6; terga 8—10 bluish green ; sternum one buff, 3-10
brown; anal appendages (Figs. 143, 144) with the superiors shortest,
inferiors longer, thickset.

507

Female. — Color similar to that of the male.

Head and thorax similar to those of the male except that the color
is paler.

Ahdomen ; terga 8-9, inclusive, brown with a median buff stripe
and a lateral stripe on each side ; tergum ten, bufif ; ovipositor buff, the
prostyles short and extending caudad of the anal appendages.

Mcdnuremcnis

Length, $ 33 mm.

Length, 9 34 mm.

Length of abdomen, 5 27 mm.

Length of abdomen, 2 28 mm.

Length of hind wings, $ 20 mm.

Length of hind wing.s, 9 23 mm.

Width of hind wings, $ 5.0 mm.

"Width of hind wings, 2 5.5 mm.

This species has not been reported from Illinois but has been re-
[lorted from Kentucky, and may possibly be taken in southern Illinois.

Described from specimens in the Bolter Collection of the Uni-
versity of Illinois and others in the collection of Mr. E. B. William-
son,— all from Florida.

Argia moEsta putrida (Hagen)

Nymph. — Color, dark brown.

Head broad and flat, pentagonal, the caudo-lateral angles project-
ing caudad and possessing a few short setae ; antennal segments dark
except the first, which is pale ; labium very broad, the median lobe but
slightly narrowed at the base and projecting strongly between the labial
palpi; mental setae wanting, the lateral marginal setae about twelve;
labial palpi with two fixed hooks, both shorter than the sharp distal
segment, the one adjacent to that segment shortest ; setae of the labial
palpi reduced to a single weak hair-like one.

Thorax brown; the pronotum projecting strongly laterad ; legs
not conspicuously banded as in apicalis, but possessing a faint preapical
ring and with the proximal two-thirds evenly infuscated ; tibiae with
dark apices; tarsi mostly pale; femora with indefinite rows of short
heavy setae ; wing-cases extending to the middle of the fourth abdom-
inal segment or beyond.

Abdomen uniform brown, the lateral keels feebly developed and
without setae ; styli of the male very long, nearly reaching the apex of

508

tlic tenth nhdominal se.s,nnent and setose on the ventral margin; apical
mars;in of the tentli alwlominal tergum cleft nearly to the hase, the
margin thickly heset with short spines; gills (Fig. 58) uniform dark
gray or nearly lilack. paler at the tip, long, broad, and bluntly pointed,
the margins parallel for a considerable distance.

Mcasurtnicnts (i/ouiui nijmphs)

Length 14 mm.

Length of abdomen 9 mm.

Length of gills 5-6 mm.

"Width of gills 3 mm.

Length of metrithoraeie wing-eases ... 4 mm.

Length of median lobe 3.5 mm.

Width of median lol)e L5-3 mm.

Descriljed from a male specimen in tiie collection of the Illinois
State Laboratory of Natural History taken from the Kankrd<ee River
si.K miles below Kankakee. June i, 1901, and se\eral specimens ob-
tained from Dr. E. M. Walker.

Adult: Male. — Color, black and cinnamon-buff.

Head : uiedian loI)e of the laliium 1)uff. sul)triangular ; di.stal seg-
ment of the palpus dark at the tip; antennae IjJack, first two segments
nearly equal, the first pale at the apex, the third segment longest; clyp-
eus and lal)runi buff, the postclypeus with two indefinite black spots
near the f ronto-clypeal suture ; lalirum with a mesal spot on the dorsal
margin; front and genac l)utT, tiie pale color extending dorsad to the
ocelli, the black confined to an indefinite ring around the median ocellus
and wedge-shaped marks on the vertex: occiput black: the surface
of the head dorsad of the postclypeus and the occiput often becomes
pollinose and obscures the original coloration.

Thorax : prothorax dark brown or black, more or less pollinose
with age; caudal lobe of the pronotum black, median lobes each with
a large, ]);de, circular, median spot wl.ich often becomes pollinose be-
fore the rest of the notum : proepinieron pale, the noto-ejiimeral suture
indistinct though marked by a lilack stripe: dorsal carina black and
a black stripe on each side one-half tiie width of the mesepisterna:
mesopleura! suture lined witii black ; mese])imera with a broad sooty
line extending the entire length of the sclerite and more than half as
wide; metapleural suture lined with black, the metepisterna and mete-
pimera and the postcoxal areas usually buf?; legs rather short, striped,
the dorsum of all femora witli a broad stripe including tlie cephalo-
ventral row of setae: tarsi and claws black; wings clear, the stigma

509

surnwunting one and one-half to two cells, the postnodal cross-veins of
the front wirtg sixteen or seventeen, of the hind wing fourteen or fif-
teen; Mo arising between the sixth and seventh or seventh and eighth
postnodals in the front wing and between the fifth and sixth in the
hind wing.

Abdomen black, with pale basal rings on segments t^-J inclusive,
faint dorsal and lateral stripes on one and two, and obscure brownish
marks on the last two segments; anal appendages (Figs. 157, 158)
consisting of short club-like superiors and broad inferiors with a
tubercle on the dorsal margin.

Female. — Color, light blue (etain blue) or olive-buff, and black.

Head, with front, genae, and vertex pale blue or butT.

Thorax light blue or buff ; pronotum blue and black, the propleura
with indistinct noto-epimeral suture and without the dorsal marginal
line of brown ; median lobes of the notum with a large pale spot on
each, and another spot about the same size covering the caudo-mesal
angles of the median lobes and the median portion of the caudal lobe ;
mesostigmal plate (Fig. 154) with a short, median, acute process
which projects caudad over the cephalic margin of the mesepisternum ;
mesepimera without the broad, longitudinal, dark stripe of the male,
usually blue except the cephalic shoulder which is buff and frequently
pollinose; all of the pleural sutures and the dorsal carina lined with
black.

Abdomen black and blue, the black confined to rather broad dorsal
stripes on terga 1-9, black spots on the caudo-lateral margins of 2-6
and the whole of sterna 1-8 ; segments nine and ten, with the exception
of a dorsal brown stripe, and the lateral valves of the ovipositor yel-
lowish ; dorsal margin of the tenth tergum with a deep mesal emargina-
tion extending nearly to the base of the segment ; superior anal ap-
pendages, short, dark, and scarcely longer than the blunt inferiors ; ovi-
positor with broad ventrally serrated, lateral valves, the prostyles short
and dark.

Measurements

Length, $ 42 mm.

Length, $ 41 mm.

Length of abdomen, $ 33 mm.

Length of abdomen, 9 31-32 mm.

Length of hind wings, $ 26 mm.

Length of hind wings, 9 26 mm.

Width of hind wings, S 5.5 mm.

Width of hind wings, 9 5.5 mm.

510

Adults of this species have been taken at Oregon in Ogle County,
at Mahrimet in Champaign County, and at Muncie and Oakwood in
\'erniili(in County, liut the species is not especially ahinidant in any of
these localities. The nymphs are reported by Ncedham ('03) as living
under stoi\cs in swift currents and by Kellicott ('99) as living on the
piles of docks in Lake Erie.

Argi.x sedul.v (Hagen)

Nyiiipli. — Unknown.

Adult; J/u/r.— Color, blue and black.

Head black and l)lue, tlie labium pale blue and buff: palpi narrow,
the second segment d-'irk and shorter than the fi.xcd hook, the cleft of
the median lobe obtuse at the base and shallow ; postclypeus pale except
a black transverse stripe along the dorsal margin; anteclypeus, labrum,
exposed portions of the manilibles, a transverse area above the clypeus,
and a spot latero-cephalad of each antenna l:)lue ; lateral ocelli w-ith small
yellow spots laterad of each, the remainder of the front and vertex
being black ; postocular blue spots large and contiguous with the mar-
gins of the compound eves; occiput and postgenac, with the exception
of rather narrow black stripes caudad of each postocular spot, yellow-
ish buff.

Tiiorax : pronotum largely black, the median lobe with large sub-
circular spots and the caud.d lolje willi a pale spot on the extreme
lateral angles, I)lue: proepimera and episterna blue; mesostigmal plates
subtriangular, not j)rojecting caudad; dorsal carina of tlie mesothorax
covered liy a broad lilack strijie which also covers about one-half of
each mesepisternum and is followed l)y a broad l)lue stripe which cov-
ers the rest of the mesepistema ; the blue mesopleural stripe is wider
adjacent to the mcsostigma and is gradually narrowed caudad; the
mesopleural suture is covered by a broad lilack stripe which also covers
most of tlie mesepimera except the cephalo-\entral shoulders, and is
considerably widened adjacent to the wing bases, enclosing a small blue
spot ; ventral lialf of the mesinf racpisterna yellow, the remainder black ;
mctapleural suture witli a narrow black line from wing liases to the
metathoracic sjiiracles; rem.'iinder of the pleura and the postcoxal areas
pale blue or l)uff ; legs ])lue and black, the coxae pale, the trochanters
black above, the femora black above and pale below, the front femora,
however, with more or less bl;ick between tlie rows of setae ; liliiae black
below, pale above; tarsi dark brown, the claws bifid at the tip; wings
with twelve to fourteen postnodal cross-veins in the front wing and
eleven to twelve in tlic bind ; ]\L. arising between the sixth and seventh

511

postnodals in the front wing and between the fourth and fifth in the
hind wing, usually nearer the fifth; stigma surmounting a single cell;
paraptera dull velvety black.

Abdomen blue and black ; basal half and a spot on the sides of the
first tergum black, the remainder blue ; dorsum and apex of the second
black, the lateral margins blue ; basal rings, and lateral marginal stripes,
extending one-half to three-fourths the length of segments 3-6, in-
clusive, blue ; the remainder of these terga, black ; tergum seven except
a small basal ring, black; dorsum of terga eight, nine, and ten blue,
the lateral margins sometimes darker ; first sternum with a black, me-
dian spot, 3-10 entirely black; anal appendages short, black, the in-
feriors longest and bifurcate (Figs. 149, 150).

Female. — Color, brown and black.

Head : front, vertex, occiput, and postgenae dull brown.

Thorax brown, the mesostigmal plates usually black and the
caudal margins forming a thin blade which projects dorsad; black
spots present on the mesopleural and metapleural sutures adjoining
the wing bases ; legs similar to the male except that the hind pair are
almost entirely pale brown.

Abdomen dull brown, with indistinct touches of blue, very similar
to that of the male except that the basal rings are not as broad or as
well defined; terga 6-10, inclusive, entirely dull brown; anal appen-
dages short ; ovipositor long and slender, extending caudad of the anal
appendages, pale brown in color.

Measurements

Length, $ 30-40 mm.

Length, 9 34 mm.

Length of abdomen, S 24-27 mm.

Length of abdomen, $ 27 mm.

Length of hind wings, $ 18-19 mm.

Length of hind wings, 9 21 mm.

Width of hind wings, S 4-4.5 mm.

Width of hind wings, 9 5 mm.

Described from a large series of males and females in the col-
lection of Mr. E. B. Williamson.

This species has been reported from Illinois.

Argia tibialis (Rambur)

Nymph, — Color, very dark brown.

Head about as long as broad, pentagonal ; eyes black ; antennae
with all segments except the last two dark on the basal three-fourths,

512

the remainder pale; tliird antennal segment longest, the second and
fourth about equal, and the first, fifth, sixth, and seventh successively
shorter; caudo-lateral margins of the head without heavy setae;
labium, when folded, extending caudad between the first and second
pair of coxae; median lobe nearly as broad as long, and with about
twelve marginal setae ; lateral setae of the labial pal])i two or three.

Thorax about as broad as long; legs with conspicuous brown
bands, the femora possessing two — a broad basal one and a narrower
preapical one — the tibiae three, one on base, one on apex, and a broader
one just proximad of the middle; tarsi with the usual ventral setae and
mostly dark; metatlioracic wing-cases reaching the apex of the fifth
abdominal segment in mature nymphs.

Abdomen dark, almost black ; lateral keels feebly developed,
hairy; dorsum of the first to the tenth terga with a pale mesal stripe
which widens slightly caudad though not as conspicuously as in the
nymph of liolacca or apicalis; gills elliptical, sometimes wholly dark,
or smoky, often possessing a broad, transverse, whitish band about the
middle and a narrower subapical one; margins densely pilose but with-
out heavy setae and the gills frequentU coarsely spotted; female ovi-
positor extending to the apex of segment ten.

Measurements

Length 12.5 mm.

Length of al)d()iii('ii 7 mm.

Length of gills 6.5 mm.

Width of gills .3 mm.

Length of metathoracic wing-cases. . .3.5 mm.

Length of median lobe 2.5 mm.

Width of median lobo 1.25-2 mm.

Adult; Male. — Color, dark purple or warm brown, sulphur-yel-
low, and black.

Head blue or I^rown ; median lobe of the labium brown, the me-
dian cleft short, obtuse at the I)asc ; proximal segment of the palpus
rather narrow, the apical segment black and slightly shorter than the
black fixed hook ; antennae black with the exception of the apices of
segments one and two, which are pale ; fronto-clypeal suture lined with
brown; clypcus, labrum, exposed portions of the mandibles and their
trochantins, genae, and front to the level of the median ocellus brown
or blue ; ocellar triangle, vertex, and the occiput, black, the black area
sending a black stripe ventrad from the vertex to each antenna, and
another enclosing the median ocellus and extending a short distance

513

ventrad where it meets a short transverse black line at right angles;
clypeus and labrum, front and vertex, thinly pilose, the setae whitish ;
compound eyes slate-colored.

Thorax brown or purple and black ; pronotum with black caudal
lube ; median and cephalic lobes also black, the median lobes each with
a small lateral brown spot ; proepimera brown, with a broad black
stripe above ; mesostigmal plates black ; dorsal carina covered by a black
stripe, the lateral halves of the stripe covering about one-fifth of each
mesepisternum, the stripes widened at the caudal and cephalic ends
and covering the stigmal plates and paraptera ; mesopleural suture cov-
ered with a broad black stripe which is frequently forked near the wing
bases, extends cephalad, and covers all of the mesinfraepisterna except
the caud(^-ventral angles and one-third of each mesepimeron :
metapleural suture with a narrow line of black, the metepisterna and
epimera brown or buff ; postcoxal areas buff, but frequently with darker
lateral margins and a pair of median spots on the intersternum; legs
mostly black, the coxae yellowish, with black cephalic surfaces, the
femora black with the exception of the dorsal carinae which sometimes
have a pale stripe ; tibiae with a paler dorsal line ; tarsi and claws black ;
anterior femoral setae eight or nine in the cephalic row, two large and
usually two small ones in the caudal row ; wings clear, the postnodal
cross-veins twelve to thirteen in the hind wing and fifteen to sixteen
in the front; Mo arising between the seventh and eighth postnodal
cross-veins in the front wing and between the sixth and seventh in the
hind wing.

Abdomen black, with sulphur-yellow and blue ; terga i-8, inclu-
sive, black, the yellow confined to lateral spots, narrow basal rings on
2-7, an apical ring on one, and narrow lines on the lateral margins of
terga 2-7 which extend about one-half the length of each segment from
the base and unite with the basal rings in segments three, .four, and
five; in older specimens, however, the lateral stripes are obscured by
more or less brown ; dorsum of the eighth and ninth terga, with the ex-
ception of the black apical margin of nine, pale blue; anal appendages
(Figs. .155, 156) black, the superiors small and black, the inferiors
black but with a paler dorsal spot.

Female. — Color, pale blue (pale methyl -blue) or buff (ochraceous
buff), and black.

Head as in the male but lighter in color, the front lacking the
vertical lines above the antennae and the transverse line below the me-
dian ocellus; postocular spots present and a pale transverse line, with
more or less yellow, on the caudo-dorsal margins of the head ; post-
genae with yellow adjacent to the compound eyes.

514

Thorax blue or brown and black ; caudal and cephalic lobes of the
pronotum with more or less blue or brown ; mesostigmal plates ( Fig.
140) without projections on the caudal margins; mesopleural stripe of
black, somewhat narrower than that of the male, separating more dis-
tinctly from the suture at the caudal third, the ventral branch fre-
quently stopping short of the caudal margin of the sclerite ; legs paler
than those of the male, the femora usually with two dark stripes one
on each side of the carina, the remainder pale blue or brown; tibiae
with a black ventral stripe between the rows of setae which frequently
includes one of tlie rows; tarsi often with the proximal segments pale.

Abdomen : lateral surfaces, ajiical ring, and narrow mesal lines of
the first tergum pale, the black confined to two dorsal basal spots; sec-
ond tergum with broad lateral blue stripes and a dorsal stripe greatly
contracted and then widened again shortly before the ape.x, the black
limited to a narrow apical ring and a dorso-lateral stripe on each side ;
segments 3-7 as in the male with the exception of a narrower mid-
dorsal pale line; tergum nine black with a paler narrow ai)ical line, the
tenth yellowish or blue, with a narrow- basal ring, the segment usually
dark below ; anal appendages of the usual type, the superiors black or
dark, the inferiors slightly paler in color; ovipositor, except the ex-
treme tip and the prostyles, dark brown or black.

Measnrcmrntft

Length, 3 34-37 mm.

Length, 9 3.^-37 mm.

Length of abdomen, S 2G-30 mm.

Length of abdomen, 9 28 nnn.

Length of hind wings, $ 20-22 mm.

Length of hind wings, 9 24 mm.

Width of hind wings. S 4.5 mm.

Widtli of hind wings, 9 5 mm.

The nymphs of this species have been taken beneath rocks in
swift currents. A single specimen has been reared and a comparison
of the nymph with the nymph- of apicclis shows them to be almost
identical. Necdham ('03) separates the two species on the character
of the lateral setae, but there is so much variation in af^icalis that the
character seems w-ithout value.

The adults are common throughout the state and may be found
at almost any point along the banks of clear, swift streams.

515

Argia violacea (Hagen)

Nymph. — Color, very dark brown.

Head pentagonal, the caudo-lateral angles nearly rectangular and
provided with a few weak setae ; antennal segments all dark except the
proximal one, which is light in color; third segment longest and the
second longer than the first ; labium short and broad, the width about
two-thirds the length ; lateral setae two or three.

Thorax short, dark larown, with a black stripe on each side ; legs
with dark coxae and trochanters, a narrow proximal ring on each
femur which is followed by two broad brownish rings, the three divid-
ing the femur into fourths; tibiae with narrow proximal rings and
rings of similar size shortly before the middle, the apices dark; tarsi
dark, though not as dark as the rings of the femora and tibiae.

Abdomen dark brown with a paler mesal stripe on the dorso-
meson ; lateral keels feebly developed and without setae on their lateral
margins; gills ovate, more than half as Lroad as long, uniform brown
or sometimes having paler V-shaped marks near the apices, the mar-
gins thickly covered with setae arranged irregularly ; ovipositor of the
female with sharply pointed lateral valves which extend beyond the
tenth abdominal segment.

Measurements

Length . 17 mm.

Length of abdomen 7 mm.

Length of gills 4.5 mm.

Width of gills 2.5 mm.

Length of metathoracic wing-eases. . .5 mm.

Length of median lobe 3 mm.

"Width of median lobe 1.25-2 mm.

Adult; Male. — Color, dark brown or purple (Matthew's purple).

Head : median lobe of the laljium pale ; distal segment of the labial
palpi black at the tip ; antennae black or dark brown except the basal
segment, which is buff; clypeus and labrum pale brown, the front, ver-
tex, and postocular regions also largely pale but becoming violet with
age, the black confined to a broad transverse band embracing the two
lateral ocelli, a T-shaped mark ventrad of the median ocellus, and nar-
row lines extending from the ends of the transverse band to the com-
pound eyes and to the caudal margins of the head ; caudo-dorsal mar-
gins of the head with a black line; occipital and postgenal regions
largely yellow ; compound eyes, slate-gray.

516

Thorax brown or violet ami black; caudal lobe of the pronotum
black and brown, the brown in lateral spots on .the lateral margins
and in a very small median spot ; median lobes each with a large sub-
circular, lateral buff spot ; proepimera buff, with dark lines marking
the dorsal liorder ; mesothorax with a Iilack line on tlic dorsal carina
and anotlier just ventrad of the mesiii)leural suture and contiguous
with the longitudinal portion of the suture for more than one-half its
length; dorsal third of the mesinfraepisternum black; metapleural
suture with a black line; metepimera and postcoxal areas buff; legs
striped, all the femora with a black stripe on each side of the dorsal
carina and the tibiae with a ventral stripe including one of the rows of
setae; tarsi dark'brown or black, the claws also black; wings clear, the
stigma surmounting a single cell or less, the postnodal cross-veins of
the front wing tiiirteen to fourteen, of the hind wing ten to eleven ;
M2 arising between the fifth and sixth postnodal cross-veins in the
front wing and lietween the fourth and fiftli in tlic liind wing.

Abdomen purple and black, or brown and l)lack ; first tergum with
a narrow, basal, black, transverse stripe, the second with large lateral
spots extending from the cephalic margin nearly to the apex; terga
tiiree and four brown or purple, with the exception of a caudo-lateral
spot on each side ; tergum five with a dark apical ring and narrow
lateral black stripes, the sixth with the purple confined to a dorsal stripe
and a basal ring, the remainder of the tergum black or dark brown ;
seventh tergum entirely black, eighth, ninth, and tenth blue on the
dorsum, black on tlie lateral surfaces; sterna i-io black; anal appen-
dages (Figs. 145, 146) consisting of short blunt superiors and longer
bifurcate inferiors.

Female. — Color, dark brown or dull violet.

Head similar to that of the male.

Thorax: dorsal mesostigmal plates (Fig. 142) with large
rounded lobes at the caudo-mesal angles.

.\I)donien witli more black than the male; terga 2-q with dorso-
lateral stripes which are broad enough on the seventh and eighth terga
to fuse on the meson ; lateral surface of tergum nine and all of ten buff,
dorsal emargination of the tenth nearly reaching the base of the seg-
ment ; anal appendages and ovipositor of the usual type, the lateral
valves of the ovipositor being serrate on the ventral margin, the pro-
styles, dark.

Measurements

Length, $ 32 mm.

TicnKth, 9 31 mm.

Length of abdomen, $ 24 mm.

517

Length of abdomen, 9 20 mm.

Length of hind wings, S 20 mm.

Length of hind wings, 9 20 mm.

Width of hind wings, £ 4 mm.

Width of hind wings, 9 5 mm.

This species is common at times along the Drainage Ditch north
of Urbana, and the nymphs may be taken at almost any season in the
black mud on the bottom of the stream. The species has not been col-
lected elsewhere in the state and it does not seem to be as common as
reported to be in Indiana. The nymphs emerge throughout June and the
adults fly as late as the first of September.

Genus Enali^agma Charpentier

The nymphs of this genus are characterized by the presence of
three, rarely four, mental setae, and five lateral setae. The gills are
variable but do not possess the long tapering points of Ischnura and
Anomalagrion, being relatively blunt at the tip. The lateral keels are
well developed and setose and in some cases present characters of diag-
nostic value for the species.

The adults in all cases have vein Mo arising between the fourth
and sixth, usually fourth and fifth, postnodal cross-veins in the front
wing and between the third and fifth in the hind wing. The number
of postnodal cross-veins varies from seven to twelve, and the female
always has a long apical seta on the eighth sternum. The eighth
sternites at the base of the cephalic pair of gonapophyses of the female
are visible and are small and subtriangular.

The genus is represented in Illinois by more species than .any other
genus of Zygoptera.

Key to Species

NYMPHS

a. Gills without pigment except in the tracheae.

b. Dark tracheal branches in alga-like patches (Fig. 76) liageni.

bb. Dark ti-acheal branches not in alga-like patfehes.

c. Lateral keel of the first abdominal segment without setae ; axis of
the gills clear.

d. Dorsal marginal setae of the median gill less than twenty in
full-grown nymphs; all of the third antennal segment dark
brown; gills rarely moi'e than 4.5 mm. in length (Fig. 72) ....
geminatum.

518 •

(111. Dorsal nitTTfrinal setae of the median sill more than twenty in
fiill-gi'own nymijhs; only the proximal third of the thii'd antcn-
nal segment dark brown ; gills commonly 5.5-6 mm. in length. .
civile.

ec. Lateral keel of the first abdominal segment with two to four
heavy setae; axis of the gills ojiatine or slightly smola*.
d. Dorsal setae of the median gill extending beyond the middle ;
mental setae four, the meso-caudal seta in each row one-half

as loiiLT or nearly as Ions as the remaining setae. . ( ct/nfliifjerum.

{ calverti.

dd. Dorsal setae of the median gill not extending to the middle

of the gill ; mental setae three, the meso-eaudal seta in each

row representing a small fourth, but minute and always less

than one-half the length of the three larger setae, carunculafum.

aa. Gills with pigment other than in the traeheae.

b. Tracheal branches of the gills in alga-like patches ; distance from
the caudal margins of the compound eyes to the eaudo-latcral angles
of the head greater than half the di.stance between the antennal
fossae. Abdomen without a median, ventral, black Hmc.
c. Dark portion of the base of the gills extending less than half

their length (Fig. 55) traviatum.

CO. Dark portion of the base of the gills extending more than half
their length.

d. Length of the gills less than eight times the greatest width;
gills of mature nymphs with a prominent hinge just caudad

of the middle (Fig. 53) cxsulans.

dd. Length of the gills eight times the greatest width; gills of
mature nymphs without a prominent hinge caudad of the

.middle (Fig. 54) antennatum.

bb. Ti-acheal branches of tlie jjills not in alga-like ])atches ; distance from
the caudal margins of the compound eyes to the caudo-lateral angles
of the head less than half the distance lietween the antennal fossae.
Abdomen with a median, ventral, black line.

c. Median gill witli a bunch of setae proximad of the first dark
transverse eross-liand : distal cross-bands of the same degree of
blackness as the proximal ones (Fig. 56) ; median gill not greatly
expanded distad of the first cross-band ; dor.sal setae of the apical

margins of the abdomiiml terga not prominent signadim.

CO.. Median gill without a bunch of setae proximad of the first dark
transverse cross-band : distal cross-bands faint, and lighter in
color than the proximal ones (Fig. 57) ; median gill much ex-
panded distad of the first cross-band ; dorsal setae of the apical
margins of the abdominal terga very prominent pollutum.

519

ADULTS

Feviales

a. Eighth abdominal tergum with a large bhie or pale spot on each side
side of the meson.

b. Dorsum of the seventh tergum blaelv (Fig. 96) geminatum.

bb. Dorsum of the seventh tergum blue, never with more than a line
of black on the meson (Fig. 95) aspersum.

aa. Eighth abdominal tergum without a large blue or pale spot on each
side of the meson.

b. Longitudinal dark stripe on the dorsum of the second abdominal
tergum dumb-bell shaped ; caudal half of the eighth tergum lilack or
dark Iravuitum.

bb. Longitudinal stripe on the second abdominal tergum not duml)-l)ell
shaped; apical half of the eighth black or dark,
c. Proximal two-thirds of the second antennal segment pale.

d. Dark stripe of the mesopleural suture reduced in width to a
mere line and much less distinct than the dorsal stripe covering
the carina; color of the thorax aliove faint blue (teneral) or
lemon-yellow (mature) and black pollutum.

dd. Dark stripe of the mesopleural suture not reduced in width
to a mere line and as distinct as the dorsal stripe covering the
carina; color of the thorax above blue (teneral) or orange
(mature) and black signatum.

cc. Proximal two-thirds of the second antennal segment brown or

black.

d. Dorsum of the tenth tergum dark ; mesopleural black stripe
of the suture not divided by a brown stripe immediately above
the suture ; caudal lobe of the pronotum without a median
mound-like elevation.

e. Mo arising beyond the fourth postnodal cross-vein in the
hind wing.

f. Mesostigmal plates with a diagonal ridge from the caudo-

mesal to the cephalo-lateral angles carunculatnm.

ff. Mesostigmal plates without a diagonal ridge from caudo-
mesal to cephalo-lateral angles.

g. Black color of dorsum of abdominal terga 4-7 always
reaching the cephalic margins (Fig. 92).
h. Mesal half of the caudal margins of the mesostigmal

plates convex (Fig. 212) civile.

hh. Mesal half of the caudal margins of the mesostigmal
plates concave (Fig. 22G) douhledayi.

520

gg. Black color of the (loi-siitn of abdominal terga 4-7 never
reaching the cci)halic margins.

h. Cephalo-mosal angles of the mesostigmal plates

rounded and hollowed out (Fig. 213) . . .ciidthirjrrum.

hh. Cephalo-mesal angles of the mesostigmal plates not

rounded or hollowed out (Fig. 223) calverti.

ce. Mo arising between the third and fourth postnodal cross-
veins in the hind wings.

f. Mesostigmal plates narrowed at middle (Fig. 227) .ebrium.
ff. Mesostigmal i)lates considerably widened at the middle

(Fig. 221) ' " Iwgeni.

dd. Dorsum of the tenth tergum i)ale ; mosopleural black stripe
divided by a brown strijte immediately above the sutui'e ; caudal
lobe of the jironotum with a median mound-like elevation (Figs.
219,220).
e. Caudal mai-gin of the mesostigmal plates at right angles to

the dorso-mcson cxsulans.

ee. Caudal margin of the mesostigmal plates not at right angles

to the dorso-meson I antennatum.

\ divagans.

Males

a. Dorsum of the second abdominal tergum with an apical spot occupy-
ing at most half of the segment ; remainder of the tergum blue,
b. Lateral .surface of the second abdominal tergum with a short lon-
gitudinal brown or black stripe geminatum.

bb. Lateral surface of the second abdominal tergum without a short
longitudinal brown or black stripe,
c. Caudal half of the seventh abdominal tergum blue ; postocular

spots connected with the blue of the occiput anpersxim.

cc. Caudal half of the seventh abdominal tergum black; postocular
spots not connected with the blue of the occiput,
d. Dorsum of the fourth and fifth abdominal tcrga more than

half black carunculatum.

dd. Dorsum of the fourth and fifth abdominal terga less than half
black.

e. Superior anal api)endages bifui'cate ebi-iiim.

ee. Superior anal apiiendages not bifurcate.

f. Inferior anal ai)pendages longer than the superiors,
g. M, arising between the third and fourth postnodal cross-
veins in the hind wings hageni.

gg. Mo arising between the fourth and fifth postnodal cross-
veins in the hind wings.

521

h. Superior anal appendages blunt ; lateral profile as

shown in Fig. 200 calverti.

hh. Superior anal appendages acute ; lateral profile as

sho^^^^ in Fig. 201 ctjatliigerum.

ff. Inferior anal appendages shorter than the superiors.

g. Superior anal appendages with the apical tubercles pro-
jecting noticeably beyond the dorso-caudal angles when

Aiewed from the side (Fig. 175) douhledayi.

gg. Superior anal appendages with the apical tubercles not
projecting noticeably beyond the dorso-caudal angles

when viewed from the side (Fig. 198) civile.

aa. Dorsum of the second abdominal tergum wholly black.

b. Second antennal segment pale except the distal third, which is dark
brown or black.

c. Dark stripe of the mesopleural suture paler in color than the
dorsal stripe covering the carina and often reduced to a mere

line polluium.

cc. Dark stripe of the mesopleural suture not paler in color than
the dorsal stripe covering the carina and never reduced to a line
signatum.

bb. Second antennal segment entirely dark brown or black.

c. Front with the blue color extending dorsad to the median ocellus ;
postocular spots forming an equilateral triangle ; black stripe of

the mesopleural suture indistinct or wanting traviaium.

ee. Fi'ont with the blue or pale color not extending dorsad to the me-
dian ocellus, not dorsad of the antennal fossae ; postocular spots
forming a wedge-shaped figure; black stripe of the mesopleural
suture distinct, never wanting,
d. Superior anal appendages bifurcate.

e. Dorsal arm of the superior appendages shortest ; arms not

widely divaricate (Figs. 203, 210) exsulans.

ee. Dorsal arm of the superior appendages as long as the ventral ;

arms widely divaricate (Figs. 202, 209) antennatum.

dd Superior anal appendages not bifurcate (Figs. 190, 197)

divagans.

Enallagma antennatum (Say)

Nymph. — Color, brown or greenish.

Head about half as long as wide, the caudo-lateral angles project-
ing strongly caudad and thickly studded with setae ; second antennal
segment slightly shorter than the first, the first two segments dark and
pilose ; labium with three mental setae, four or five lateral ones, and

522

with seven or eight setae on the lateral margins of the median lobe;
labium extending just caudad of the first pair of coxae.

Thorax about half as wide as the head; the femora all with pre-
apical rings on the distal third ; tibiae with the usual apical scales ; tarsi
pale : metathoracic wing-cases extending beyond the cephalic margin of
the fourth abdominal segment.

Abdomen slender, the lateral keels well developed on segments
1-8 but almost wholly lacking in setae except the seventh, which some-
times possesses a single weak one; gills (Fig. 54) long and slender,
somewhat lanceolate, with a gradually tapering tip; the smaller
tracheae are collected in alga-like patclies, and the gills arc always pro-
vided with some dark cuticular pigment ; there is a light spot on the
apical third or fourth of the gill on each side of tlie axis as in cxsiilaiis
which is often followed by two dark cross-bands, the extreme tip, how-
ever, being light in color; female ovipositor extending to the middle of
the tenth sternum.

Mens\irements

Length 13-14 mm.

Lciiprth of a])doiii('n 9 nun.

Length of gilLs 7-8 mm.

Width of gills 1-1.3 mm.

Length of metathoracic wing-cases. . .4 mm.

Length of median lobe 1.6 mm.

Width of median lobe 5-1.2 mm.

The nymph is very similar to cxsiilaiis lint may be distinguished
from that species by means of the more slender gills, the cross-bands
at the tip in older individuals, and by the absence of a hinge beyond
the middle.

Adult; Male. — Color, blue or greenish yellow and black.

Head black and orange; mouth-parts buff, the median lobe of the
labium subtriangul;ir, the median cleft shallow, acute; proximal seg-
ment of the palpus comparatively narrow, the apical half of the distal
segment dark ; antennae dark, the ape.x of the first; two segments some-
times lighter in color; a large portion of the postclypeus and a dorso-
mesal spot on the labrum, black ; anteclypeus, the remainder of the
labrum, exposed portions of the mandililes, their trochantins, the genae,
and a transverse stripe above the clypeus orange; remainder of the
front and vertex dull black ; postocular spots cuneiform, connected with
the narrow stripe of the caudo-mesal margin; occiput and postgenae
\ellow except a black stripe caudo-ventrad of the postocular spots;
compound eyes slate-gray.

523

Thorax yellcnv or blue, and black ; pronotum blue and black, the
cephalic lobe largely blue, the median lobes black with small lateral blue
spots and with median spots, but only in very recently emerged speci-
mens ; caudal lobe of the pronotum with a small, pale, mesal spot, the
remainder black ; mesostigmal plate with a pale lateral spot and a
smaller spot on the caudo-mesal angle ; dorsal carina lined with blue,
on each side of which there is a broad black stripe occupying about half
or more of each inesepisternum ; beyond these dorsal stripes on the
mesepisterna there are narrow, pale stripes; mesopleural suture cov-
ered by a broad black stripe which extends cephalad onto the mesinfra-
episternum and covers one-third of it ; interpleural fold with a black
dash near the wing bases; remainder of the thorax pale greenish yel-
low.

Abdomen black, greenish yellow, and blue; terga i-8, inclusive,
and ten with black dorsal longitudinal stripes, the stripes widened sub-
apically on segments 2-5. inclusive, and narrowed to the meson at the
apex of eight ; apical black rings on terga 2—5 and on eight ; lateral sur-
faces of terga 1—8, inclusive, with basal interrupted rings except on the
first, which has an apical pale yellowish green ring ; lateral sur-
face of the eighth tergum and all of the ninth blue; sterna 2-8 with a
black ventral mesal line; superior anal aiipendages (Figs. 202, 209)
black, bifurcate, the arms about equal and widely divaricate; the in-
feriors shorter, directed obliquely dorsad, mostly buff, the tips black.

Female. — Color similar to that of the male.

Head similar to that of the male.

Thora.x similar in color to that of the male ; prothorax with a small
spot on each median lobe near the meson, besides the lateral ones, and
the mesopleural black stripe more commonly divided by a brown line
immediately over the suture.

Abdomen: terga i-io with broad dorsal brown or black stripes,
the stripes widened subapically on segments two to six and continuous
with a dark apical ring on the same segments ; tergum nine with a nar-
row pale line, sometimes diamond-shaped ; lateral surfaces of terga
2-7 inclusive, greenish yellow; sterna 1-7 or 1-8 with a black mesal
line; eighth sternum with a very long and heavy apical seta and the
anal appendages of the usual type; ovipositor including the prostyles
not extending caudad of the anal appendages, the ventral margins of
the lateral valves serrate ; eighth sternites small, triangular.

Measurements

Length, 3 34 mm.

Length, 9 32 mm.

524

Length of abdomen, 5 28 mm.

Length ol' a})domcn, $ 2't mm.

Length of hind wings, £ li) mm.

Length of hind wing.s, 9 19 mm.

AVidth of hind wings, i 4 mm.

Width of hind wings, 9 4 mm.

A relatively rare species which lias not Ijcen collected outside of
Champaign County. The nymphs are to be found in the same locality
where c.vsiilaiis is abundant and the two are frequently taken together.

Enallagma ASi'EHSUM (Hagcn)

Nymph. — Unknown.

Adult; Male. — Color, blue and black.

Head blue and black; mouth-parts buff, the median lobe subtrian-
gular and with a shallow acute cleft; ])alpi narrow, the distal segment
pale ; antennae black ; postclypeus black, anteclypeus and the la])rum
brown or buff and a blue transverse stripe above the clypeus to the level
of the antennal fossae ; remainder of the front and vertex black ; post-
ocular spots I)lue, tlie blue connected with the blue of the occiput and
postgenae.

Thorax blue anil black ; ])ronotum black except the narrow cephalic
lobe, which is blue ; procpimera black above, blue or pale below ; meso-
stigmal plate narrow and about half blue; mesothorax with a broad
dorsal stripe, covering the carina and also half of the mesosupraepi-
sterna on either side; this is followed by a blue stripe which occupies
most of the remaining portion of the mesosupraepisternum ; meso-
pleural suture covered with a I)lack strijie wliicli is considerably
widened near the caudal margin of the mesiiifraepisternum and extends
cephalad over that sclerite, covering the dorsal half or third ; remainder
of the thorax blue or buff; paraptera entirely black; legs black and
buff, the coxae and the trochanters pale, the femora with a stripe on'
the cephalic surfaces including one row of setae ; tarsi and claws black,
shining ; wings with nine postnodal cross-veins irv the front wing and
eiglit in the hind wing; M._, arising between the fourth and fifth post-
r.odal cross-veins in the front wing and between three and four in the
I'ind wing.

Abdomen blue antl I)lack ; terga mostly blue, but a very narrow-
basal spot on the first tergum, a dorsal apical spot and ring on the
second, tiie apical tiiree-fourths of the dorsum of tiie third, dorsum
of the fourth, all of five and six except narrow basal rings, the pro.ximal
half of seven, and all of the dorsum of ten, are black; lateral margins

525

of the fourth, fifth, and sixth terga are mostly pale yellow; anal ap-
pendages (Fig. 195) black, the superiors much longer than the in-
feriors and with a ventral basal tubercle, the apices blunt and directed
ventrad; inferiors conical, sharply pointed, and directed obliquely
dorsad.

Female. — Color similar to that of the male.

Head similar to that of the male except that the postocular spots
are not connected with the blue of the caudal portion of the occiput.

Thorax similar to that of the male ; mesostigmal plates black.

Abdomen (Fig. 95) with terga 1-6 as in the male, seven with
dorsal stripe reduced to a mesal line on the basal three-fourths, sud-
denly widened at the apex; eighth tergum black, with a pair of pale
basal spots connecting with the pale lateral margins ; dorsum of nine
and ten black, the lateral surfaces pale ; ovipositor short, the prostyles
blunt and dark, the ventral margins of the lateral valves serrate.

Measurements

Length, $ 27-32 mm.

Length, 9 34 mm.

Length of abdomen, $ 22-25 mm.

Length of abdomen, 9 26 mm.

Length of hind wings, S 16-18 mm.

Length of hind wings, 9 20 mm.

Width of hind wings, S 3-3.7 mm.

Width of hind wings, 9 4 mm.

Described from a specimen taken at Lexington, Ky., August,
1915, and a number of both sexes in the collection of E. B. WilHamson.
Reported from Illinois.

Enallagma calverti Morse

Nymph. — Color, buff.

Head subelliptical, the caudo-lateral margins projecting a little
caudad and with a few setae ; antennae of the usual form, the third
segment longest, the second longer than the first ; labium extending
caudad to the second pair of coxae ; mental setae four, lateral setae six,
and the marginal setae on the margin of the median lobe five or six.

Thorax : legs with rows of heavy setae, especially prominent on
the femora, which have several rows and a group of longer setae near
the apices; tibiae with two ventral rows of long setae, and a thick bunch
of scales at the apices ; tarsi of the usual form and with thick ventral

526

rows of setae ; nietathoracic wing-cases extending caudad to the middle
of the fourth abdominal segment.

Abdomen long and slender, uniform buff, the cuticle provided
witli minute setae; segments 3—10 with dorsal tr.uisverse rows of setae
at the caudal margins and segments ^-/ with similar ventral rows, the
setae grouped somewhat conspicuously 1 >n the meson ; lateral keels
strongly developed, setose, the keel of the first segment with a number
of heavy setae, usually three, tiiat of ih.e second with a row of eight or
nine, and keels of the third to the eighth segments with a row of ten or
twelve, and with groups of two or three at the apices ; ninth segment
with a lateral row of setae in line with tjie lateral keels; gills (Fig. 80)
^•ery long, somewhat spatulate, the points mostly blunt. ;md the dorsal
iiiarginal row of setae of the meilian gill extending much beyond the
middle ; three narrow transverse bands .sometimes occur just beyond
the middle; they are placed closely together as a rule, l)ut the bands
may be reduced to one or may be wantmg.

Measiu'cv^ents

Length 15 mm.

Length of abdomen 9 mm.

Length of gills 7 mm.

Width of gills 1.8 mm.

Length of median lube 2.3 mm.

Width of median lobe 8-1.6 mm.

Described from three specimens in the collection of the State
Laboratorv of Natural Histurv, collected at Havana, 111., Tune 30,
1897.

The nymph has not been reared, but the specimens were deter-
mined from a description given by W;dkcr.

/hhilf; Male. — Color, blue and black.

Head blue and black, buff below; laljium i)uff, the median lobe
subtriangular, the apical cleft narrow ; distal segment of the labial palpi
pale; postclypeus black except the lateral margins. ;mteclypeus, l.abrum,
mandibles, their trochantins, genae, and the transverse area above the
dypeus blue ; lateral ocelli with a small blue spot cejihalad of each, the
remainder of the front and vertex black ; jiale line caudad of the ocellar
area distinct, the ends narrowly separated from the large blue, cunei-
form postocular spots; occiput pale except a transverse black line bor-
dering the postocular spots.

Thorax blue and black ; pronotum mostly black, with a large blue
spot on eacli median lobe, the caudal margin df the caudal lobe and

527

most of the cephalic lobe blue ; proepimera blue, the dorsal border with
a broad black stripe ; mesothorax with a blue dorsal carina, the black
stripe on each side occupying about half of each supraepisternum ;
mesopleural suture covered by a black stripe which is suddenly widened
caudad of the infraepisterna; dorsal third of the mesepimeron black;
nietapleural suture with a black spot adjacent to the wing bases;
paraptera black, the cephalic margins blue ; remainder of the pleura
blue ; postcoxal areas buff ; legs striped black and blue, the coxae largely
blue ; trochanters blue, dark above ; femora with black stripes occupy-
ing the whole of the dorsum, but not extending ventrad far enough to
include either row of setae; cephalic margins of all femoral black
stripes emarginate at the proximal end ; cephalic half of the tibiae black,
the stripe including the cephalo-ventral row of setae; tarsi uniform
brown, the segments darker at the distal end; wings with 12-13 post-
nodal cross-veins in the front wing and 10— 1 1 in the hind ; Mo arising
between the fifth and sixth postnodal cross-veins or near the fifth in
the front wing, and between the fourth and fifth in the hind ; stigma
small, pale brown, and surmounting slightlv less than a single cell.

Abdomen blue and black; terga 1-5 inclusive, blue with the excep-
tion of a black spot on the dorsum of one, a subapical dorsal spot and
apical ring on two, and apical spots and rings on 3-5 ; caudal half of the
dorsum of six and caudal three-fourths of seven, black ; terga eight
and nine blue ; tenth tergum black above, pale buff on the lateral mar-
gins; first sternum pale; sterna 3-8 black ; parameres black and not
reaching the apex of the segment; anal appendages short (Figs. 200,
207), the superiors blunt, shorter than the inferiors, but without the
conspicuous tubercle of cizilc and caniiiciilatniii; inferiors slender,
acute and black at the tips.

Female. — Color, blue, but paler than that of the male.

Head : the blue of the male is replaced by brown or buff.

Thorax similar to that of the male, but the blue is frequently re-
placed by brown or buff.

Abdomen blue and black, the first tergum with a black basal spot
as in the male, spot of the second tergum connected with the apical ring
and a liaie on the meson extending to the base- of the sclerite ; terga
3—6 with narrow dorsal black lines widened suddenly near the apices
of the segments and occupying the caudal three-fourths ; seventh ter-
gum with a similar but broader dorsal line; caudal half of the dorsum
of the eighth, and all of the ninth and tenth black ; lateral margins of
Till terga pale ; sterna 3—7 black ; one, two, eigl^t, and ten pale ; ovi-
positor pale, the lateral valves broad. ■ ji

528

Measurements

Length, S 33-35 mm.

Length, $ 34 mm.

Length of abdomen, s 26 mm.

Length of iil)domen, 5 26 mm.

. Length of hind wings, s 19 mm.

Length of hind wings. 9 21 mm.

Width of hind wings, 6 4 mm.

Width of hind wings, 9 4-4.5 mm.

This species is closely related to caniiicluatuiii, ck'ilc, douhlcdayi,
and cyathigcritm. The adult male is easily distinguished from those
species by means of the anal appendages; the female, less easily, by
means of the mesostigmal plates.

Illinois is within the range of the species and it probably occurs
within the state although there seems to be no record of its presence.

A large number of adults of both sexes have been examined, all
in the collection of Mr. E. B. Williamson.

Enallac.ma carunculatum Morse

Xy)upli. — Color, green or buff.

Head about twice as Ijroad as long, the caudo-lateral margins not
projecting strongly, but with a few strong setae : antennae with the
ihirtl segment longest, the second longer than the first, the first two
and the proximal portion of the third d;'.rker than the rest ; mental setae
of the median lobe three, and sometimes a small fourth on each side;
lateral setae six ; marginal setae of the median lobe eight or nine on
each side; labium extending caudad between the first and second pair
of coxae.

Thorax : legs pale, tlie femora with very faint or no preapical
rings and distinct rows of moderately heavy setae; tibiae and tarsi
with the usual apical scales and ventral setae; metathoracic wing-cases
extending about to the middle of the fourth abdominal segment.

Abdomen with well-developed lateral keels, the keel of the first
segment with three or four setae; the second, with eight to twelve;
third, with aI)out eleven; fourth, with thirteen to fifteen; fiftli. eighteen
to twenty; sixth, eighteen to twenty; seventh, twelve to fourteen; and
the eighth with about fourteen; on the fifth and sixth keels the setae
are bunched at the apc.x, with sometimes as many as three together;
venter of the alwlomen entirely without small setae on the cephalic seg-
ments, but usually with long hair-like setae on the dorsum of segments

529

two, three, and four. In mature nymphs there is an indefinite, dark
dorsal stripe extending from near the apex of the third segment to the
seventh or eighth ; gills (Fig. 70) transparent, lanceolate, with a broad,
usually pale, opaque stripe along the axis from the base to near the tip ;
dorsal marginal setae of the median gills usually more than twenty in
mimber and extending one-third the length of the gill from the base,
the ventral setae of the same gill consisting of only a few setae and
extending half as far as the dorsal row; ventral marginal setae of the
lateral gills of similar extent to the dorsal setae of the median gill ;
apical margins usually without setae or hairs ; ovipositor of the female
extending to the middle of the tenth abdominal segment and the lateral
valves with about four heavy setae on the ventral margin.

Measurements

Length 13.5-14 mm.

Length of abdomen 8-9 mm.

Length of gills 5.5-6 mm.

Width of gills 1.2 mm.

. Length of metathoraeie wing-eases. .3.6 mm.

Length of median lobe 2.5 mm.

Width of median lobe 5-2 mm.

Adult; Male. — Color, dark blue or Ijuff and black.

Head blue or buff and black, the labium buff, the median lobe
subtriangular, the palpus moderately narrow ; antennae entirely black,
the first segment paler at the apex; postclypeus with a large, shining
black spot, the ventro-lateral margins pale; anteclypeus, and labrum
except a dorso-mesalblack spot and a dorso-lateral spot on each side,
pale ; exposed portions of the mandibles, their trochantins, the genae,
and a transverse stripe above the clypeus, pale ; remainder of the front
and vertex dull black; postocular spots oval, buff or blue, and not
usually connected with the stripe caudad of the ocellar area; occiput
and postgenal regions pale except a black stripe caudo-ventrad of the
postocular spots.

Thorax blue or buff and black, the pronotum dull black with a
transverse median stripe on the cephalic lobe, the caudal margin of
the caudal lobe and small crescentic spots on the lateral margins of the
median lobe buff or blue; dorsal third of the proepimera black, the
dorsal suture indistinct, the remainder of the sclerite buff or blue ; ceph-
alo-lateral angles of the mesostigmal plates elevated, the elevated por-
tion pale ; pale stripe of the mesosupraepisternum regular, the margins
parallel and straight, the stripe extending from the cephalic margin

530

ncarlv to the paraptcra ; black stripe <if the mesopleural suture widest
just caudad of tlie mesiiifraepisternum, extending (mto and covering
about the dorsal third of that sclerite, the stripe continuous at the
caudal extremity with a narrow stripe extending ventrad along the
caudal margin of the mesepimemn to the interi)leural fold ; metapleur.'d
suture with a Iilack spot adjacent to the wing bases; remainder of the
thorax buff or blue; legs striped, buff and black, the coxae and
trochanters usually pale, the femora with broad dorsal stripes from
bases to apices; til)iae with dorsal strijies covering about half the dorsal
surface and including the cephalo-ventral row of setae ; tarsi and claws
pale, black at the tips, the claws very long; w-ings with nine to eleven
postnodal cross-veins and with AL arising near the fifth postnodal
cross-vein in the front wing and between four and five in tlie hind
wing.

Abdomen black and blue or buff; terga i-6, inclusive, blue or
buff, except a small black liasal spot on one, a black apical ring and
('<^rsal spot occup\-ing iialf the second and third terga. another covering
slightly more than half the fourth, two-thirds of the fifth and sixth,
and all of the seventh except the narrow lateral marginal stripes and
a basal ring; dorsum of the tenth tergum black; eighth and ninth terga
entirely blue or buff; sterna one and 3-8 with a median black line; anal
appendages (Figs. 194, 205) short, the superiors usually black, blunt,
and with a narrow notch on the dorsum cephalad of but near the dorso-
caudal angle; inferiors paler, the black apices directed strongly dorsad
and fre(|ucntly in contact with the superiors.

Female. — Color similar to that of the male.

Head similar to that of the male ; the postocular sjjots are, how-
ever, considerably smaller.

Thora.x similar to that of the male.

Abdomen with the dorsum of terga i-io with broad, dorsal dark
stripes, widened subajiically on segments 2-4 inclusive, the pale color
occupying the larger ])art of the lateral surfaces of all terga as lateral
stripes which are continuous with the broad uninterrupted basal rings
f>n segments 4—7 and the interrujited ring of the third tergiun; sterna
1-8 with a mesal black line from the bases to near-the apices, the eighth
sternum with a long ajiical seta ; lateral valves of the ovijiositor broad,
pale, the ventral margins serrate from apex nearly to base, the pro-
i-tyles darker on the apical half.

Measuremenis

Length, $ 33 mm.

Longth, 9 32 mm.

531

Length of abdomen, S 26 mm.

Length of abdomen, S 25 mm.

Length of hind wings, $ 19 mm.

Length of hind wings, 9 19 mm.

Width of hind wings, 3 4 mm.

Width of hind wings, 9 4 mm.

An inhabitant of the lake regions of Illinois, the nymphs prefer-
ring floating vegetation or rank growth along the banks of ponds or
lakes of considerable size, though they are occasionally to be en-
countered in the larger and clearer streams.

The color of the recently emerged adult is buff or cream-color and
biack, and the blue is much slower in appearing than in other species.

Enai.l.a.gma civile (Hagen)

Nymph. — Color, green or buff.

Head about twice as broad as long, the caudo-lateral angles not
projecting caudad or laterad, but armed with short setae ; antennae
with the third segment longest, the first shorter than the second, the
first two segments and the proximal portion of the third dark brown,
the remainder of the third and the distal segments pale; labium ex-
lending just caudad of the first pair of coxae, the median lobe with
three or four mental setae, the labial palpi with five or six lateral setae
and a row of seven or eight small setae on the margin of the median
lobe.

Thorax pale buff' or green; legs very pale, the preapical femoral
rings indistinct, the femora w-ith a dorsal and lateral row of setae and
scales near the tips: metathoracic wing-cases extending caudad to the
middle of the fourth abdominal segment.

Abdomen pale buff or green, frequently with an indefinite darker
stripe on the dorsum of segments 3-7, the cuticle sparsely provided
with minute setae, which are usually lacking on the venter of the
cephalic segments ; dorsum of two, three, and four with long hair-like
setae ; lateral keels well developed and setose, the first w'ithout setae,
the second with a row of about eleven, the third with twelve, the
fourth with sixteen, fifth with eighteen to tw-enty, sixth with fifteen to
sixteen, seventh with twelve to fourteen, and the eighth with a straight
row of about nine setae; gills (Fig. 75) lanceolate, colorless and
usually without pigment except in the smaller tracheae, the margins
very transparent ; dorsal marginal setae of the median gill extending
less than half the length of the gill from the base, and composed of
more than twenty setae ; ventral row of the lateral gills slightly longer

I

532

and about half the length of the gills; female ovipositor extending to
the middle of the tenth abdominal segment, the ventral margins of the
lateral valves setose, the row consisting of about eight stout setae and
a number of hair-like ones.

Measurements

Length 15 mm.

Length of abdonipii 10 mm.

Length of gills 6 mm.

Width of gills 1.8-2.1 mm.

Length of mctathoi-acic wing-eases. .4.5 mm.

Length of median lobe 3.1 mm.

Width of median lobe 8-2.3 mm.

Adult; Male. — Color, dark blue and black.

Head blue and l)Iack; mouth-parts butt, the median lobe of the
labium subtriangular. with a shallow, acute, median cleft, the labial
palpi much broader at the proximal end than at the apex; antennae
dark brown or black; postclypeus with a shining black spot on the
meson ; anteclypeus shining yellow ; labrum shining yellow with a black
dorso-mesal spot ; exposed portions of the mandibles, trochantins, and
genae pale, and a pale stripe above the clypeus extending dorsad to the
level of the anteimal fossae ; remainder of the front and vertex dull
black; postocular spots oval or subcuneiform, the pale line caudad of
the ocellar area not distinct ; occiput and postgenae yellow, except a
transverse black stripe caudo-ventrad of the postocular spots; com-
pound eyes dark brown or black.

Thorax blue and black, the black usually metallic ; pronotum
black, the cephalic lobe with a pale transverse line, the median lobe
with a pale spot on the lateral margins and the caudal lobe also with
pale margins ; proepimera witli l)lack doi'sal borders, pale below ; meso-
stigmal plates subquadrangular, the cephalo-lateral angles somewhat
elevated, though not as much so as in caruiiculatnm, and the lateral
half covered by a yellow spot; dorsal black stripe regular and covering
nearly half of each supraepisternum ; pale stripe of the supraepisterna
broadest dorsad of the mesinfraepistcrna, extending nearly to the
paraptera; mesopleural black stripe of the suture narrowed cephalad
of the wing bases, broadest shortly caudad of the mesinfraepistcrna
and extending across rmd covering about one-third of the latter; caudal
margin of the mescpimera black to the level of the inter])leural suture;
metapleural suture with a black spot cephalad of the wing bases; re-
mainder of the i)leura blue, tiie ])ostcoxal areas buff, liecoming polH-
nose; paraptera black, the cephalic margins pale and a pale spot below
the lateral angles; legs striped, tlie coxae and trochanters pale, the

533

femora with stripes on the dorsum, the tibiae with black stripes occupy-
ing half the dorsa, but not reaching the apices of the segments ; tarsi
and claws pale, dark at the tip, the claws notched at a considerable dis-
tance proximad of the tip ; wings with nine or ten postnodal cross-veins,
the vein Mo arising between the fourth and fifth postnodal cross-veins,
usually near the fifth, in the front wing, and between the fourth and
fifth in the hind wing.

Abdomen blue and black, the cephalic terga largely blue, the
caudal ones darker and frequently becoming pollinose with age ; terga
1-6. inclusive, blue except a small basal spot on the dorsum of one and
black shield-shaped apical spots and apical rings on 2-6; dorsal black
spot of the sixth tergum occupying about half the dorsum, those of
2-5 about one-fourth ; dorsum of the seventh and tenth terga black
except the lateral margins and a narrow, basal, interrupted ring on the
seventh ; all of the eighth and ninth terga blue ; sterna 2-10 with a black
median line; anal appendages (Figs. 198, 103) short, the superiors
blunt, with a narrow cleft or notch just ventrad of the apex; inferiors
usually black and shorter, the black tips directed oblicjuely caudad and
dorsad and f recjuently in contact with the superiors.

Female. — Color similar to that of the male.

Head similar to that of the male.

Thorax similar to that of the male except in the color of the legs,
which are usually lighter, the dorsal stripes of the femora never ex-
tending to the proximal ends of those segments.

Abdomen : the dorsum of all terga have a black longitudinal stripe
from the bases to the apices and a short, narrow, apical, Iilack ring;
margins of all terga yellow or blue, the pale color extending onto the
dorsum at the bases of segments 2-6, but always forming interrupted
rings and never connected across the dorsum (Fig. 92) as in caritn-
ctilatiim (Fig. 91) ; sterna 1—8 with a mesal line from bases to apices,
the apex of the eighth sternum with a heavy seta which is darker at
the tip than at the base; anal appendages of the usual form, the ovi-
positor with yellow lateral valves, the ventral margins of which are
serrate from the apex to near the base ; prostyles brown, dark at the tip.

Measurements

Length, $ 29-32 mm.

Length, S 30-32 mm.

Length of abdomen, S 23-24 mm.

Length of abdomen, V 23-24 mm.

Length of hind wings, $ 17 mm.

■ Length of hind wings, 9 19-20 mm.

Width of hind wings. S 3.5-4 mm.

Width of hind wings, 9 3. .5^ mm.

I

534

A common species at Urbana. It was not taken at Havana, where

canincuhitini! was abundant, nor at Lake A'illa, where both caruncii-
latiiin anil hagciii were cimimon. The females of these closely allied
species have been determined from material collected in the above
localities. A study has also been made of specimens taken in copula,
in the collection of Mr. E. B. Williamson.

The imago emerges at Urliana as early as June 13 and apparently
continues to emerge thrf)ughout the season. Nymphs taken late in
July emerged shortly after, and another lot, collected at Lexington,
Ky.. emerged as late as August 18. 191 5. There is a possibility that
the species has two broods a year.

Ex.^Li^.'VGMA CY-XTHIGERTM (Charpentier)

Nymph.— Co\qv, bufY.

Head elliptical, the cautlo-lateral angles rounded and sparsely
setose; antennae of the usual form, the second segment sliglitly longer
than the first; labium ijroad, and extending caudad to tlie mesocoxae;
mental setae four, the proximal seta of both rows more than half as
long as the remaining ones ; lateral setae five or six ; marginal setae
of the median lobe four or five.

Thorax : femora without conspicuous rows of small setae ; wing-
cases extending caudad to the middle of the third abdominal segment.

Abdomen with distinct lateral keels all of which are setose in-
cluding those of the first segment ; the size of the setae gradually
increases caudad, and on each lateral surface of the ninth segment
there is a row of setae in line with tlie later;d keels with two or
more setae grouped together at the caudal end of the row; gills (Fig.
71) clear and without cuticular pigmentation though reported liy
Lucas ('00: 103) to have one or more narrow cross-bands beyond
the middle ; dorsal and lateral gills with closely placed marginal setae
which extend more than half-way from the bases to the ajiices of the
gills; tracheal l)ranc]ics few in numlier and usually larger tiian are
found in civile or caniticulatiim; ovipositor of the female extending
caudad to the caudal margin of the tenth abdominal .segment.

Measurements

Length 14 mm.

Length of abdomou 9 mm.

Length of gills 5 mm.

Width of gills 1.5 mm.

Length of niotathoraeie wing-cases. . . .4 mm.

Length of modiaii lobe 2.5 mm.

Width of median lobe 75-2 mm.

535

Described from three nymphal exiivia from France (Martin),
obtained from Mr. E. B. Williamson.

Adult; Male. — Color, pale blue and black.

Head black, blue, and buff; mouth-parts buff; median lobe sub-
triangular, the proximal segment of the labial palpi broad, the distal
segment pale; antennae dark, the second segment much longer than
the first ; postclypeus black except the lateral margins and the ventral
margin, the anteclypeus, labrum, mandibles, and the transverse stripe
above the f ronto-clypeal suture blue ; genae, pale yellow ; remainder
of the front and vertex black ; postocular spots large, blue, the margins
of the spots irregular and the spots narrowly separated from the
narrow stripe caudad of the ocellar area; occiput, except a stripe
caudad of the postocular spots and the postgenae, pale blue.

Thorax : pronotum largely black, the cephalic lobe with the cephalic
half blue, median lobes with large oval blue spots; proepimera and
episterna blue with black dorsal borders; mesostigmal plates narrow
and more than half pale; dorsal carina with the black stripe which
covers it also covering one-half of each supraepisternum ; black stripe
of the mesopleural suture narrowed considerably caudad and covering
about one-third of the mesinf raepisterna ; remainder of the mesopleura,
except a small spot on the mesopleural suture near the wing bases,
pale blue; postcoxal areas yelli)wish blue; legs with blue coxae and
trochanters, the trochanters dark on the dorsum ; femora with a single
black stripe on each dorsum, the stripe broken by a small spot at the
base ; cephalic half of the dorsum of the tibiae with black longitudinal
stripes; tarsi pale yellow, darker at the distal ends; wings with twelve
postnodal cross-veins in the front wing and ten in the hind ; stigma
surmounting less than a single cell, pale.

Abdomen blue and black ; first tergum with small basal and
smaller lateral black spots ; second tergum blue with a subelliptical
apical spot and an apical ring; terga three, four, and five with apical
spots connected with the apical rings; apical half of the sixth and
about four-fifths of the dorsum of the seventh with broad black stripes
expanded caudad but not reaching the margins of the terga ; terga
eight and nine pale ; dorsum of ten black, the caudal margin distinctly
incised on the meson, the lateral surfaces of the segment pale yellow;
first sternum pale, 3—8, inclusive, black; anal appendages (Figs. 201,
;2o8) black and brown, the superiors short, bent ventrad and some-
what acute at the apex; inferiors much longer than the superiors and
black at the tips.

Female. — Color in general similar to that of the male, the blue,
however, replaced by yellow.

536

Head and thorax similar to those of the male except that they
are somewhat lighter in color ; mesostigmal plates as shown in Figure
213.

Abdomen with broad longitudinal stripes on the second tergum
which are much expanded near the caudal margin ; terga 3-7 with
narrow longitudinal stripes, all of which are expanded near the caudal
margin, the longitudinal stripe of eight much reduced near the cephalic
margin (Fig. 93); anal appendages of the usual type; ovipositor
short, the lateral valves pale, ventral margins slightly serrate; pro-
styles short and blunt.

Measxirements

Length, S 31-32 mm.

Length, 9 31-32 mm.

Length of abdomen, $ 24 mm.

Length of abdomen, $ 26 mm.

Length of hind wings, S 19-21 mm.

Length of hind wings, 9 20 mm.

Width of hind wings, S 4 mm.

AVidth of hind wings, 9 4 mm.

This species is most closely related to cakrrfi, from which the
female differs in having more black on the dorsum of the eighth
tergum and in the characters of the mesostigmal plates. The male
may be distinguished by means of the anal appendages.

Described from a number of both sexes in the collection of Mr.
E. B. Williamson. The species has not been reported from Illinois,
but probably occurs here.

Enallagma divagans Selys

Nymph. — Unknown.

Adult; Male. — Color, blue and black.

Head blue and black ; labium pale, median lobe subtriangular, the
labial palpi including the distal segment pale, the proximal segment
narrow; antennae dark, the first two segments subequal, the first
pale at the tip; postclypeus black, anteclypeus except a small dorso-
mesal black spot, the mandibles, their trochantins, genae, and a trans-
\erse area above the fronto-clypeal suture pale blue; remainder of
the front black; vertex with pale subcuneiform postocular spots,
the remainder of the dorsal portion black; occiput and postgenae pale
blue or bufif with the exception of a large black spot laterad of the
occipital foramen on each side.

537

Thorax blue and black ; pronotum black, cephalic lobe largely blue,
the median lobes with large spots adjacent to the proepimera, and the
caudal lobe with small spots on the lateral angles and one on the meson ;
proepimera distinct blue and with a dorsal, crescentic, black spot;
mesostigmal plates largely blue, the mesal angles black ; mesosupra-
episterna black, with blue longitudinal stripes from the cephalic mar-
gins to the wing bases, the stripe slightly widened cephalad, narrowed
at the middle, and widened again caudad ; mesopleural suture covered
by a black stripe which occupies a portion of the supraepisterna and
the epimera, being widest about the middle, narrowed near the wing
bases, extending cephalad across the infraepisterna and covering about
one half of those sclerites; remainder of the pleura blue, with the ex-
ception of spots on the interpleural fold and metapleural suture ad-
jacent to the wing bases ; legs bufif or pale blue and black ; coxae blue
with a black basal spot on the cephalic surfaces; dorsum of the
trochanters dark, remainder pale; femora with slight dorsal carina,
the dorsal longitudinal stripes usually covering the carinae, but the
stripes sometimes divided by a pale line on the carina, and emarginate
at the proximal end ; tibiae mostly pale with faint cephalo-dorsal
stripes or row of dashes, the ventral surfaces with black spots at the
base and apex; tarsi pale, the segments darker at the distal end; wings
with twelve postnodal cross-veins in the front wing and ten in the
hind wing ; stigina pale, surmounting less than a single cell ; M^ arising
near the fifth postnodal cross-vein in the front wing and between three
and four in the hind wing.

Abdomen blue and black with a touch of bronze; first and second
terga blue, with black, dorsal, longitudinal stripes, the first with a very
narrow subapicah ring of black which does not reach the lateral
margins ; longitudinal stripe of the second tergum expanded subapically
and the tergum with a broader apical ring extending from the meson
half-way to the lateral margins; terga 3-7 with dorsal longitudinal
stripes which are contracted to the meson near the cephalic margin,
but widen subapically and unite with the black apical rings; terga
eight and nine entirely blue; dorsum of the tenth tergum entirely
black, the venter pale blue or buff; anal appendages (Fig. 190) short,
black, the superiors bilobed, the dorsal arm knob-like, the ventral
lobe more slender; inferiors slender, directed obliquely dorsad and
frequently in contact with the ventral arm of the superiors; first
sternum pale, 3-9 black.

588

Female. — Color similar to that of the male.

Head similar to that of the male.

Thorax : black stripe of the mesopleural suture divided by a line
of brown ; mesostigmal plates as shown in Figure 224.

Abdomen: terga 1-7, inclusive, similar to corresponding terga
01 tlie male, the lateral blue stripes of the margin becoming dull
brown on the apical segments ; eighth tergum black, with pale blue
lateral spots on the caudal margin; tergum nine blue, with two short
dorso-lateral black strijies which fuse at the base of the meson;
tergum ten blue; anal ajjpendages dark brown, ovipositor pale buff,
the prostyles short and blunt.

Measurements

Length, S 29-33 mm.

Length, 9 32 mm.

Length of abdomen, 3 24-28 mm.

Length of abdomen, $ 26 mm.

Length of hind wings, S 17-18 mm.

Length of hind wings, V 18 mm.

Width of hind wings, S 3.5 mm.

Width of hind wings, 9 3.5 mm.

This species is very closely related to c.rsulaiis. tlie male differing
principally in the possession of blue on the eightli tergum and in the
character of the anal appendages. The female can !iot be separated
from, cxsidans except by the mesostigmal plates. It is, however, a
nnich more slender and delicate insect.

Described from eighteen males and one female in the collection of
Mr. E. B. Williamson.

A rare species, reported from Ohio, but not yet taken in Illinois
by collectors.

Enallagma doubledayi Selys

Nyinpli. — Unknown. ,

Adult; Male. — Color, light blue and black.

Head blue and yellowish and black; antennae uniform brown,
the second segment slightly longer than the first ; anteclypeus and
labrum shining yellow; exposed portions of the mandibles, their
trochantins, genae, and the front dorsad of the clypeus to the level of
the antcnnal fossae pale ; remainder of the front black ; jiostocular spots
small, the narrow stripe caudad of the ocelli distinct; occiput and post-
genae pale ; compound eyes dark brown.

539

Thorax black, blue, ami yellowish green ; pronotvim black, the
cephalic lobe, a small spot on each median lobe, and the caudal margin
of the caudal lobe pale; proepimera and episterna pale, the noto-
epimeral suture indistinct; paraptera black; mesothorax with a broad
black dorsal stripe, the stripe covering about one-third of the meso-
supraepisterna on each side ; remainder of the thorax, including the
postcoxal areas, buff with the exception of small dark spots on the
metapleural sutures near the wing bases; legs black and yellow, the
coxae and trochanters pale, darker on the cephalic surfaces ; femora
each with a broad black dorsal stripe which frequently includes one
row of setae; tibiae with longitudinal stripes on the cephalic surfaces;
wings with about ten postnodal cross-\eins in the front wing and eight
in the hind one; Mj arising between the fifth and sixth postnodal
cross-veins in the front wing and between the fourth and fifth in the
hind wing.

Abdomen blue and black; terga i-io blue except a small basal
spot on the first, a hastate spot on the second, an apical spot and
marginal ring on the second to the fifth, the apical half or two-fifths
of the dorsum of the sixth, dorsum of the seventh (excepting a narrow
interrupted basal ring), and the tenth, which are pale; anal appendages
(Figs. 169,175) similar to those of carunculatnm and civile, but the
superiors differ (compare Fig. 169 with Figs. 176 and 179) in having
a smaller pale tubercle at the end and in being much wider proximad
of the tubercle.

Female. — Color, similar to that of the male.

Head similar to that of the male.

Thorax: mesostigmal plates (Fig. 226) similar to those of civile,
but the caudal margins concave, instead of convex as in the latter.

Abdomen : terga i-io with broad dorsal dark stripes and basal in-
terrupted rings, the lateral margins pale ; anal appendages of the usual
type and the ovipositor pale, the ventral margins of the lateral valves
serrate.

Measurements

Length, $ 31 mm.

Length, ? 31 mm.

Length of abdomen, $ 25 mm.

Length of abdomen, 9 24 mm.

Length of hind wings, $ 17 mm.

Length of hind wing.s, 9 18 mm.

540

Described from a number of specimens in tiie collection of E. B.
Williamson.

This species has not been reported from Illinois. It has been
collected in Ohio and was originally described from Florida. It is
possible that it may occur occasionally in southern Illinois.

Enallagma ebrium (Hagen)

Nymph. — Not available for study.

Adult; Male. — Color, blue and black.

Head black and blue; mouth-parts pale, the labium with a sub-
triangular median lolie; labial palpi buff, the distal segment dark at
the apex; antennae black except the tips of the first and second seg-
ments; postclypeus black; anteclypeus, labrum, exposed portions of
the mandibles, their trochantins, genae, and a transverse stripe above
the clypeus, pale; remainder of the front and vertex black; postocular
spots large, subcuneiform, the margins irregular; occiput and post-
genae pale except a transverse black stripe caudo-ventrad of the post-
ocular spots.

Thorax blue and black ; pronotum black, the cephalic lobe with a
l)ale transverse stripe, median lobes with pale spots on the lateral and
caudal margins of the caudal lobe ; dorsal border of the proepimera
black, the ventral two-thirds pale ; mesostigmal plates elongate, the
lateral angles covered with a pale spot and slightly elevated, though
not as much as in caruiicitlatiim or chile; dorsal mesothoracic stripe
occupying about one-third of each supraepisternum, the lateral margins
parallel; pale stripe of the supraepisterna extending from the cejihalic
margin to near the paraptera, widest al)(ive the infraepisternum ; ])lack
stripe of the mesopleural suture widest just caudad of the infraepi-
sternum, and extending across and (iccup\ing about one-half of that
sclerite; caudal margin of the nietepisterna black and a black spot on
the metapleural sutures cephalad of the wing bases; remainder of the
pleura blue, the postcoxal areas buff; paraptera black. trapez(Mdal,
the cephalic margins and a spot just below the lateral angles pale;
legs striped, black and liuff, the femora and coxae pale, the entire
dorsum of the femora black except a small spot near the base, fre-
quently appearing as an emargination of the black dorsal stripe; tiiiiae
with a l^lack stripe from base to near tlie apex. (Kcupying half or less
of tile dorsal aspect and often including the ceplialo-ventral row of
setae; tarsi and claws pale, dark at the tips; wings with nine to ten
postnodal cross-veins in the front wing; vein M.j arising between tlie

541

fourth and fifth postnodal cross-veins hi the front wing and between
three and four in the hind wing.

Abdomen bhie and black ; terga largely blue, with black spots on
the base of the first and the apices of 2-6 inclusive, all of the dorsum
of seven blue except a basal interrupted ring, and all of ten blue;
terga eight and nine blue; sterna 3-8 with mesal lines of black from
the cephaHc to near the caudal margins; anal appendages (Figs. 189,
196) short, pale, the superiors bifid, the two arms ecjual in length;
dorsal arm of the superior appendages black at the tip and forming
a blunt hook ; ventral arm pale and nearly straight ; inferior appendages
pale, dark at the tips and about as long as the superiors.

Female. — Color, black and yellow or blue.

Head similar to that of the male, the blue, however, sometimes
replaced by yellow.

Thorax similar to that of the male; mesostigmal plates as shown
in Figure 227.

Abdomen with broad dorsal stripes on segments 2-10, the stripes
contracted to the meson on the bases of terga 3-7 inclusive, and
widened subapically on segments 2-7, the widened portion not reach-
ing the lateral margins; first tergum pale, with a black spot at the
base; sterna 1-8 with black median stripes; ovipositor of the usual
form and not reaching caudad of the tenth segment, the ventral mar-
gins of the lateral valves feebly serrate.

Measurc7ncnts

Length, $ 29 mm.

Length, 2 29 mm.

Length of abdomen, S 23-25 mm.

Length of abdomen, 9 24 mm.

Length of hind wings, S 16-17 mm.

Length of hind wings, 9 18 mm.

Width of hind wing.s, S 4 mm.

Width of hind wings, 9 4 mm.

The anal appendages of the male distinguish the species from
closely allied members of the genus, and the mesostigmal plates of the
females are also characteristic.

Described from a number of males from Illinois in the collection
of the State Laboratory of Natural History, and from females in the
collection of E. B. Williamson.

542

Enallagma exsulans (Hagen)

Nymph. — Color, dark lirown or greenish.

Head slightly hroader tlian long, the caudo-lateral angles pro-
jecting caudad and provided with heavy setae; second antennal seg-
ment shorter than the first, the lirst two darker than the remaining
ones and pilose; lal)ium extending just caudad of the procoxae, mental
setae three in nunil)er: lateral setae four or five, and six or seven
marginal setae on tlie median lobe.

Thorax : legs with a few hair-like setae, the femora each with a
preapical ring of brown and the tibiae with the usual scales at the tip;
apices of the third tarsal segments and the apices of the claws dark;
nietathoracic wing-cases extending caudad to the fourth al)dominal
segment.

Abdomen slender, the cuticle provided with minute setae and
minute brown spots ; lateral keels well developed on segments i-8,
the keels on segments 4—8 and the lateral apex of segment nine with
small groups of two to five setae; gills (Figs. 53, 77, 77a) I)roadl}'
lanceolate, broadest beyond the middle, usually heavily pigmented on
the proximal two-thirds, the area of infuscation being followed by
two large clear spots on each side of the axis, the distal end of the
gill being dark, the extreme tip white; marginal setae of the median
gill consisting of a dorsal row extending from the base to the light
spots, or nearly two-thirds the length of the gills, and ventral marginal
setae of the lateral gills of similar extent; apical margins of all gills
hairy ; smaller tracheae forming alga-like patches ; ovipositor extend-
ing to the middle of the tenth abdominal segment.

Measurements

Length 12-13.5 mm.

TjpnRth of abdomen 9-10 mm.

Lonfith of gills 5.5-7 mm.

Width of gills 1.8-2 mm.

TiOiisth of median lobe 2 mm.

Width of median lnl)c 6-1.8 mm.

Adult; Male. — Color, pale i)lue, black, and brown.

Head pale blue and black ; median lobe of the labium bufif, sulv
triangular, the cleft oI)tuse at the base; antennae entirely black; post-
dypeus Ijlack, shining, tlie anteclypeus pale and the labrum with a
transverse black stripe on the dorsal margin; exposed portions of the
mandibles, their trochantins. genae, atid a transverse area between

548 •

the compound eyes and above the clypeus, pale blue ; remainder of the
front, and the vertex, black ; postocular spots and the postgenae and
occiput yellow.

Thorax blue and black ; pronotum largely black, the cephalic lobe
blue; large spots on each mesal lobe and a smaller one on each, near
the meson, blue, and a blue triangular mesal spot on the caudal lobe;
proepimera largely blue, the dorsal sutures indistinct and covered with
black ; mesostigmal plates elongate, the lateral angles covered by a
blue spot; dorsal carina with a broad, black stripe, which covers also
about one-half of the mesosupraepisterna on each side ; the dorsal stripe
is followed on each supraepisternum by a narrower blue stripe extend-
ing from the cephalic margin caudad to near the paraptera, the stripe
being narrowed at both ends ; the black stripe of the mesopleural
suture is broad, extends ventrad well onto the metepimera, and in
younger specimens is divided by a brown line which is directly over
the suture ; dorsal third of the mesinfraepisterna, and spots on the
metapleural sutures near the wing bases, dark brown or black; re-
mainder of the pleura blue, postcoxal areas brownish or buff; legs
pale blue, or brown and black, the coxae and trochanters pale, the
femora each with a faint dorsal carina on one side of which is an indefi-
nite line and on the other a row of spots, the hind femora, however,
often entirely pale ; tarsi and claws pale, dark at the tips ; wings with ten
to eleven postnodal cross-veins and IV'L, arising between the fourth and
fifth postnodal cross-veins in the front wings and between three and
four in the hind wing.

Abdomen blue and black, the dorsum of terga 1-9 and ten with
longitudinal black stripes from base to apex, widened subapically on
segments 2-7 and narrowed to the meson on the apex of the eighth
tergum; lateral surfaces of terga 1-8 and ten, all of nine, narrow
apical ring on one, narrow basal ring on three, and a broad basal
ring on four, five, and six, blue or pale; anal appendages (Figs. 203,
210) black, the superiors bifurcate, the dorsal arms shortest and with
minute points directed mesad ; inferiors paler and shorter than the
superiors. ,

Female. — Color, pale green (pale viridine green), black, and
brown, tip of the abdomen blue.

Head similar to that of the male except that the postocular spots
are connected with the narrow stripe caudad of the ocelli, and the
genae and stripe above the clypeus are usually more or less orange in
color.

544

Thorax with the brown of the mesopleural dark stripe covering
the suture more conspicuous and persistent than it is in the male;
mesostigmal plates as shown in Figure 220.

Abdomen with broad dorsal stripes on segments 1-8, the stripe
on nine being reduced to two trianguhir spots at the base of the tergum,
the remainder being blue in color ; tergum ten blue ; lateral surfaces of
terga 2-8 and narrow interrupted basal rings on segments 3-8 pale
green ; sterna 2-8 with black mesal lines, the eighth with a long apical
seta ; ovipositor and anal appendages of the usual form, the lateral
valves of the ovipositor blue or pale and serrate on the ventral margins ;
prostyles dark brown.

ileasiirements

Length, s 35 mm.

Length, 9 32 mm.

Length of abdomen, S 29 mm.

Length of abdomen, 2 26 mm.

Length of hind wings, S 19 mm.

Length of hind wings, 9 20 mm.

Width of hind wings, S 4 mm.

"Width of hind wings, 2 5 mm.

One of the most common and wide-spread species of the state.
The nymphs prefer meadow brooks, but also inhabit small lakes and
ponds. In numbers this species is equal to siguatum. The adults
emerge early and fly throughout the summer.

Specimens have been seen from Dubois, Carbondale, Carmi,
Golconda, Lake Villa, Oregon, and Cook County.

Enai^IvAGMa geminatum Kellicott

Nymph. — Color, usually green.

Head about three times as broad as long, elliptical, the caudo-
lateral angles not projecting caudad or laterad, evenly rounded, and
possessing only a few setae; third segment of the antennae longest
and the second segment decidedly longer than the first ; segments r-3 or
1-4, dark in color ; labium extending slightly caudad of the procoxae ;
median lobe with three mental setae and sometimes a minute fourth ;
lateral setae five; median process of the labial palpi with only two
teeth; lateral margins of the median lobe with three or four small
setae caudad of the articulations of the labial palpi.

Thorax : legs without dark rings near the apex or with very faint
ones, the femora provided with rather long setae ; tarsal claws dark at

545

tlie tips; metathoracic wing-cases extending to the caudal margin of
the fourth abdominal segment.

Abdomen with moderately well-developed lateral keels on seg-
ments one to eight inclusive, the first without setae, the second with a
bunch of three or four, the third with an irregular double row, and
tlie fourth to the eighth possessing irregular single rows, with some-
times two setae at the apices; segment nine, although possessing no
keel, has an irregular double row of setae in line with the keels of the
preceding segments; gills spatulate to lanceolate (Fig. 72), without
pigment except in the smaller tracheae and sometimes a trace along
the axis; dorsal marginal row of setae of the median gill extending
much less than half the length of the gill and containing seventeen or
eighteen setae, the ventral row of the same gill short and composed of
only a few setae ; ventral marginal row of the lateral gills also less than
one-half the length of the gills; the black tracheae of the gills differ
greatly from those of other clear-gilled species in being fewer in num-
ber and branching from the axis more nearly at right angles ; oviposi-
tor extending caudad to the apex of the tenth abdominal segment.

Measurements

Length 11-12 mm. ■,

Length of abdomen 9 mm.

Length of gills 4.7 mm.

Width of gills 1.3 mm.

Length of metathoracic wing-cases ... 2 mm.

Length of median lobe 2 mm.

Width of median lobe 6-1.5 mm.

Adult; Male. — Color, pale blue (pale methvl-blue), black, and
buff.

Head blue and black, the mouth-parts buff, with a tinge of blue;
median lobe of the labium subtriangular, the cleft shallow and rounded
at the proximal end ; labial palpi with slender distal segments, pale,
and not darker at the tip ; antennae dark brown or black, the tips of the
first and 'second segments sometimes pale; postelypeus shining black
except the latero-ventral angles, which are blue; anteclypeus and
labrum except a small dorso-mesal black spot, blue ; exposed portions
of the mandibles, their trochantins, genae, and a transverse area dorsad
of the clypeus blue; remainder of the front black; postocular spots
large, blue, rather irregular and frequently serrate on the margins;
pale stripe caudad of the ocelli wanting; occiput and postgenae buff,

546

except a transverse stripe caudad of each postocular spot ; compound
eyes dark Ijrovvn above, the lirown area inckuhng a crescent-shajjed
paler stripe, the eyes pale yellow below.

Thorax blue and black, buff below; pronotum black, the narrow
cephalic lobe and the caudal lobe largelv l)lue, the median lobes entirely
black; proepimera largely blue; mesostigmal plates narrow, the lateral
angles and the caudal margin with a broad l)lue stripe ; black stripe
of the dorsal carina covering one-third to one-half of each mesosupra-
episternimi ; sujiraepisternal l)luc stripe somewhat irregular, not reach-
ing the caudal margin of the sclerite, contracted at the caudal third
or fourth, and occasionally interrupted, forming an exclamation point;
mesopleural l)lack stripe of the suture widest adjacent to the infra-
episternum and covering the dorsal third of that sclerite; at the caudal
extremity the stripe extends ventrad along the caudal margin of the
mesepimera to the interpleural fold ; metapleural suture with a black
line; remainder of the pleura, including the ventral half of the mes-
epimera, all of the metepisterna, and the epimera, blue ; postcoxal
areas pale or buff; legs striped, black and blue or buff, the coxae and
the trochanters mostly pale, the coxae sometimes with dark spots;
femora each witli a l)road dorsal strijjc from base to the apex and
the tibiae with a brown or black stripe occupying half the dorsum and
frequently including the cephalo-ventral row of setae; tarsi and claws
black, the claws deeply bifid at the tip ; wings with seven to nine post-
nodal cross-veins and with Mo arising between the fourth and fifth
pcstnodal veins in the front wing and between three and four in the
hind wing.

Al)domen blue, buff', and black; first tergum blue, a black basal
spot occupying half the dorsum, and the caudo-lateral margin black;
second tergum blue except a subapical dorsal spot, an apical ring,
and a longitudinal stripe near the lateral margin, which are black;
segments 3—7 with longitudinal black stripes on the dorsum from
near the bases to the apices, the stripes widened subapically, connecting
with the apical rings and extending to the lateral margin of the terga;
entire dorsum of tergum ten and a harrow lateral marginal stripe from
bases to apices of terga eight and nine black or dark I)rown, the
whole of the dorsum of the eighth and ninth terga pale blue ; lateral
margins and basal rings of terga 3-6 pale yellow or blue, the lighter
color connecting across the dorsum on the bases of the third and
fourth terga and extending onto the dorsum but interrupted on tlie
meson in terga 5-7; anal appendages (Figs. 204, 211) black and buff',
the superiors black, with paler tips, and curved ventrad and caudad ;

547

inferiors slightly longer than the superiors, yellowish buff with black
tips, the tips directed mesad.

Female. — Color, similar to that of the male.

Head similar to that of the male except that the dorsal half or
third of the labrum is usually brown.

Thorax similar in all respects to that of the male; mesostigmal
plates as shown in Figure 216.

Abdomen with broader dorsal stripes on terga 2—/, all of which
extend to the bases of the segments ; terga nine and ten entirely brown
except the pale lateral margins; tergum seven brown, with large blue
spots occupying the larger portion of the sclerite and separated from
one another only by a mesal line of black; dorso-apical margin of
seven and eight blue; sterna 2-8 with a black mesal line, the eighth
with a long apical seta; anal appendages of the usual type, the lateral
valves of the ovipositor broad and serrate on the ventral margins;
prostyles dark brown, short.

Measurements

' Length, S 26-27 mm.

Length, 2 26-27 mm.

Length of abdomen, S 21 mm.

Length of abdomen, 9 21 mm.

Length of hind wings, S 15 mm.

Length of hind wings, 9 16 mm.

Width of hind wings, 3 3.5 mm.

Width of hind wings, 9 4 mm.

Tiiis species is characteristic of the smaller lakes and larger
ponds, the nymphs inhabiting floating vegetation, and the adults flying
near the surface of the water close to the habitat of the nymphs. The
nymphs do not live in meadow brooks or swift streams.

Both nymphs and adults were taken at Havana, Illinois, and at
Lake \^illa during the latter part of Jtme and the first of July.

Enallagma hageni (Walsh)

' Nymph. — Color, buff or greenish.
Head subelliptical, the caudo-lateral angles projecting slightly
caudad and armed with a few heavy setae; antennae with the third
segment longest, the second longer than the first ; labium, when folded,
extending caudad to the second pair of coxae, the mental setae of the
median lobe three, the lateral setae usually five, and the marginal
setae of the median lobe usually three or four.

548

Thorax nearly uniform in diameter throughout, the prothorax
somewhat smaller; legs with faint i)reapical femoral rings of brown,
and the usual apical scales present on tlie tibiae ; tarsi and claws pale ;
metathoracic wing-cases extending to the middle of the fourth ab-
dominal segment.

Abdomen slender, and with a row of spots on the cephalo-lateral
angles of the tcrga and sterna of segments 2-9; lateral keels strongly
developed, setose, the first keel usually without setae, the second,
third, and fourth with a bunch of four or five at the apices, the fifth
with about five apical setae and a weaker row extending to the base
of the segment ; sixth, seventh, and eighth keels with six setae at the
apices and a proximal row of about nine setae on each; segment nine
without lateral keel, but with a row of setae along the line of the lateral
keels, composed of two heavy setae near the caudal margin and a
straight row of six smaller setae extending cephrdad to the margin
of the segment; cuticle of the abdomen without dark spots at the
bases of the minute setae which cover the surface ; dorsum of seg-
ments two and three and the base of four with long hairs; gills (Fig.
76) lanceolate, almost colorless, widest beyond the middle and rather
obtusely pointed ; tracheae pigmented in certain areas which form
al)Out twelve alga-like patches around the margins of the gills; dorsal
marginal setae of the median gill extending half-way from the base
to the tip and composed of more than twenty setae; ventral setae of
the lateral gills extending more than half-way from the base to the
tips of the gills; apical margins of all gills with a few scattered hairs.

Measurements

Length 14-15 mm.

Length of abdomen 9 mm.

Length of gills 5 mm.

Width of gills 1.8 mm.

Length of metathoracic wing-cases. .3.6 mm.

Length of median lobe 2 mm.

Width of median lobe 7-1 mm.

Several specimens obtained from Dr. E. M. Walker have been
studied. Specimens of this species are also present in the collection of
the Illinois State Laboratory of Natural History and have been iden-
tified by comparison.

Adult; Male. — Color, pale blue and black.

Head black and yellowish, the mouth-parts buff, the median lobe
of the labium subtriangular ; antennae black or very dark brown ;

549

postclypeus largely black, the anteclypeus and the labrum shining
yellow; exposed portions of the mandibles, their trochantins, genae,
and a transverse stripe dorsad of the clypeus yellow; remainder of
the front black; the oval postocular spots and the narrow transverse
stripe caudad of the ocelli green; occiput and postgenae pale; com-
pound eyes dark brown.

Thorax black, blue, and yellowish green; pronotum dull black,
the cephalic lobe, a small spot near the lateral margin of each median
lobe, and the caudal margin of the caudal lobe yellowish green; pro-
epimera pale, the noto-epimeral sutures indistinct ; mesostigmal plates
with a pale lateral spot ; paraptera black ; mesothorax with the usual
dorsal stripe, a broad pale stripe on each supraepisternum, and a black
stripe covering the mesopleural suture, extending over the infraepi-
sternum, and covering about one-third of that sclerite; remainder of
the thorax, including the postcoxal areas, yellowish green or blue with
the exception of a small dark spot on the metapleural suture just
cephalad of the wing bases; legs black and yellow, the coxae and
trochanters pale, the femora each with a broad black dorsal stripe
from base to apex, and the -tibiae with a similar stripe on the cephalic
surfaces, which frequently includes one of the rows of setae; tarsi
and claws brown, black at the apices ; wings with ten postnodal cross-
veins in the front wing and about eight in the hind one; M, arising
between the fourth and fifth postnodal cross-veins in the front wing
and between the third and fourth in the hind wing.

Abdomen blue and black; terga i-io blue except a small black
basal spot on the first, an apical spot and marginal ring on the second
to the fifth, the apical half or two fifths of the dorsum of the sixth,
the dorsum of the seventh except a narrow interrupted basal ring,
and the dorsum of the tenth, which are black; anal appendages (Figs.
161,162) short, the inferiors subcorneal, the superiors slightly shorter,
broad and flat, subquadrangular when seen from above, pointed, and
similar in appearance to the inferiors when seen in lateral profile.

Female. — Color, yellowish green and black.

Head similar to that of the male.

Thora.x also like that of the male; the mesostigmal plates (Fig.
221) are characteristic, being short and broad and having the caudo-
lateral angles distinctly elevated; the blue of the male thorax is usually
replaced by a yellowish green.

Abdomen black and yellow; terga i-io black except the lateral
surfaces and an apical ring on the first, lateral surfaces of 2-10, and
interrupted basal rings on 3-6 inclusive, which are pale blue or green-

550

ish; anal appendages of the usual type; the lateral valves of the ovi-
positor are pale yellow, the prostyles light brown ; apex of the eighth
sternum with a long seta.

Measureine7its

Length, S 30 mm.

Length, 9 30 mm.

Length of abdomen, S 23-24 mm.

Length of abilomcn, 9 23-24 mm.

Length of hind wings, $ 17 mm.

Length of hind wings, 9 17 mm.

Width of hind wings, S 3.5 mm.

Width of hind wings, 9 4 mm.

A common species in the lake region of Illinois, but not observed
as far south as Urbana. The adult female is closely related to cantiicu-
latu)}i and ck'ilc, from whicli it may be separated by means of the
wing venation, the vein Mo usually arising between the third and
fourth postnodal cross-veins, by the narrower pale abdominal rings at
the bases of the terga, and Iiy the character of the mesostigmal plates.
The males are easily separated from canmciilatiiiu and ck'ilc liy means
of the anal appendages.

Enai.i,.\gm.\ roLi.uTUM (Hagen)

Ah'i-nph. — Color, pale green or huff.

Head elliptical, about twice as broad as long, the caudo-lateral
angles slightly projecting and furnished with but few setae; antennae
of the usual form as regards length of the segments, the first two
segments, however, being much thicker than the distal ones and the
second usually shorter than the first; first antennal segment dark in
color, the remaining ones paler; labium extending slightly caudad of
the first pair of coxae, with three mental setae ; five lateral setae and
tiiree or four marginal setae on the median lobe.

Thora.K about twice as long as broad; legs light in color, with
a few scattered setae, the femora with preapicah rings of brown, the
tibiae sometimes with a dorsal row of black dashes; metathoracic
wing-cases reaching the midillc of the third abdominal segment.

Abdomen slender, the lateral keels strongly developed and setose,
the setae being grouped conspicuously near the apices of the keels,
especially on segments 2-6; dorsa of segments 4-10 with apical trans-
verse rows of small setae, the row on the tenth interrupted on the
line of the meson, and those on 2-5 irregular, and consisting of several

551

rows together; ovipositor extending to the middle of the tenth ab-
dominal segment, the ventral margins of the lateral valves with a
si.'.gle row of setae ; venter of the abdomen without the median black
stripe of signatitui, but with a double row of black spots near the
apical margins, two on each of segments one to six and sometimes
on seven also; gills (Fig. 57) lanceolate, frequently much and suddenly
widened beyond the middle, conspicuously banded, usually with two
darker cross-bands (more or less fused) near the proximal third
and three lighter crescentic ones which are sometimes wanting, axis
dark, the median gill without dorsal marginal setae, the ventral margins
of the lateral gills with a thick row extending slightly more than
one-third the length of the gills from their bases, or extending from
the base to the point where the first dark cross-band reaches the margin.

Mcasuremenis

Length 15.5 mm.

Length of abdomen 9 mm.

Length of gills 5.5 mm.

Length of metathoracic wing-eases. . .4.1 mm.

Length of median lobe 1.8 mm.

Width of median lobe 5-1.5 mm.

Adult; Male. — Color, lemon-yellow (strontian yellow) or very
pale blue, and black; the majority of specimens are yellow, the blue
tenerals being infrequent.

Head yellow and black ; labium pale yellow, median lobe subtri-
angular; antennae brown and pale, the first segment and basal two-
thirds of the second pale, the remainder dark brown ; postclypeus
with a large black spot occupying almost the whole of it and within
which are two small yellow spots ; anteclypeus and labrum yellow
except a median, dorsal, brown spot on the labrum ; exposed portions
of the mandibles, trochantins, genae, and a transverse area above
the clypeus extending dorsad to the level of the median ocellus, yellow ;
remainder of the front black except a small transverse stripe
cephalad of the median ocellus and small spots cephalo-ventrad of
the lateral ocelli ; postocular spots large, cuneiform, connected with
the narrow stripe caudad of the ocellar area ; the black of the vertex
extends along the margin of the compound eyes a short distance
caudad and ventrad of the postocular spots and sends mesad a broad,
short band ; remainder of the occiput and postgenae pale yellow.

Thorax yellow and black ; pronotum yellow and black, the broad
cephalic lobe mostly yellow, the median lobes each with a large yellow

552

spot and a smaller one mesad of it; caudal lobe with a yellow caudal
margin; proepimera yellow, with very little black or brown; mesostig-
mal plates subtriangular, yellow, with a small brown spot near the mesal
margin, the caudo-mesal angles slightly elevated, dorsal carina covered
by a broad black stripe, the lateral margins of which fade into brown;
black stripe of the mesopleural suture reduced to an indefinite pale
brownish area near the middle of the horizontal portion of the suture ;
black spots adjacent to the dorsal margin of the mesinfraepisterna
and small spots just cephalad of the wing bases; dorsal third of the
mesinfraepisterna marked with small, crescentic, black spots; meta-
pleural sutures with small black spots just cephalad of the wing bases;
remainder of the mesopleura yellow; paraptera black with yellow
cephalic margins and pale spots ventrad of the lateral angles; legs
mostly yellow, the coxae and trochanters pale, the femora with a
faint dorsal line, the tibiae with a faint indefinite dorsal line or row
of dashes, and the tarsi and claws tipped with brown; wings with
nine to eleven postnodal cross-veins and with JNL arising between the
fourth and fifth postnodal veins in the front wing and between three
and four in the hind wing.

Abdomen yellow and black, the dorsum of terga i-8, inclusive,
with black longitudinal stripes from near the base to the apex of
each; lateral stripes on terga 1-7, narrow basal rings on 3-7, and a
very narrow apical ring on the first tergum, yellow; all of the ninth
and tenth terga blue except a narrow mesal line on the tenth ; sterna
3-8 with a mesal line of black; anal appendages (Figs. 186, 193)
brown, the superiors much longer than the inferiors, broad at the-
apices, and with the caudo-dorsal and caudo-ventral angles folded
mesad; inferiors small and yellow, the black apices directed mesad.

Female. — Color, lemon-yellow or very pale blue, and black.

Head similar to that of the male.

Thorax of slightly paler tint than in the male; mesostigmal plates
(Fig. 225) with a large lateral black spot, the lateral margins rounded,
and the plates contiguous with the mesinfraepisterna.

Abdomen yellow and black, the terga similar to those of the
male with the exception of nine and ten. which "are usually yellow,
the ninth having a triangular black spot at the base ; sterna 2-8 with
a mesal line of black, the eighth with a long seta at the apex; lateral
valves of ovipositor yellowish, serrate on the ventral margins, the
prostyles brown.

Measurements

Length, $ 34 mm.

Length, 9 34 mm.

553

Length of abdomen, $ 28 mm.

Length of abdomen, 5 27 mm.

Length of hind wings, $ 19 mm.

Length of hind wings, 2 21 mm.

Width of hind ■\\ings, $ 4 mm.

Width of hind wings, 9 3.5 mm.

A species of apparently local distribution, occurring in the lake
region of Illinois. Several collections of nymphs and adults were
made at Lake Villa, July 13 and 14, 191 5, and a number of adults
were reared from the nymphs.

While closely related to signatum. the nymph shows a great dif-
ference in the gills, making it recognizable at sight. It is quite different
from the species figured by Walker as polliitiiin ('13 ; pi. i, fig. 10), and
his description also differs from the specimens obtained at Lake Villa.

ElSTAtLAGMA SIGNATUM (Hagen)

Nymph. — Color, buff or greenish.

Head elliptical in outline, the caudo-lateral angles not projecting
strongly, but thickly studded with short setae; first two segments of
the antennae dark in color, nearly ecjual in length, the second slightly
shorter, the third longest, and the remaining ones decreasing succes-
sively in length; labium, when folded, extending just caudad of the
procoxae, with three mental setae, five lateral, and three or four
smaller ones on the margin of the median lobe.

Thorax : legs light in color except a dark ring on the apical third
of each femur and the tips of the third tarsal segments; femora with
a few small setae and scattered hairs ; metathoracic wing-cases extend-
ing nearly to the fourth abdominal segment.

Abdomen : the segments of the abdomen appear to have a greater
transverse diameter near the apical fourth on account of the projecting
lateral keels ; the keels are well developed and setose, the setae being
grouped mainly at one point near the apex of the keel; dorsum of
segments 4-8 with short apical rows of small, heavy setae, terga
nine and ten with longer rows, usually extending onto the venter;
sterna two, three, and four with a cluster of Small thick setae on the
apical third, and the venter with a black line extending from the basal
segment to segment nine; gills (Figs. 56, 69) lanceolate, the dorsal
marginal setae of the median gill grouped mainly at one point, usually
just proximad of the point where the first transverse band reaches
the margin; beyond the ventral marginal row of setae the margins
of the lateral gills are distinctly emarginate ; the pigmentation of the

554

gills consists of three to five broad, black cross-bands and a broad
axial band from the bases to the apices ; ovipositor extending to the
middle of the tenth abdominal segment.

Measurements

Length 16-18 mm.

Length of abdomen 10.5-12.5 mm.

Lcusth of gills 5.5 mm.

Width of gills 1 .(> nmi.

Length of mctathoracic wing-eases. . . .4 mm.

Length of median lohc 2 mm.

Width of median lohc 5-1.8 mm.

Adult; Male. — Color, pale bine or oran.sjc. and black.

Head blue or orange, ami I)lack ; mouth-parts buff, the median
lobe of the labium subtriangular, the palpi pale; first two segments
of the antennae pale, at least much paler than the distal ones, the
second segment darker at the tip ; postclypeus black, sometimes with
a pair of median pale spots, one on each side of the meson ; anteclypeus
pale ; labrum pale, the dorsal margin with a mesal black spot and
two lateral ones, or with a transverse stripe of black including the
three spots; exposed portions of the mandibles, their trochantins.
genae, and a transverse stripe above the clypeus extending slightly
dorsad of the antennae, orange or blue; remainder of the front and
vertex black; postocular spots large, cuneiform, and yellow or blue;
postgenae and the occiput largely yellow.

Thora.x orange or blue, and black ; pronotum black, the cephalic
lobe, a subcircular spot on each median lobe, and the entire caudal
lobe blue or yellow; the spots on the median lobes are variable, being
frequentlv subcircular with an emargination on one side; in younger
individuals there are also two smaller spots mesad of the large spots
on each mesal lobe; proepimera blue or yellow, the dorsal margins
covered by a black stripe; stigmal plates triangular, the caudo-mesal
angles elevated, and the caudal margins with a blue or yellow stripe;
dorsal carina covered by a black stripe, the margins of which are
parallel and very straight ; mesopleural suture also with a broad stripe
which is widest just caudad of the mesinfraepisternum and extends
cepiialad and covers the dorsal third of that sclerite; remainder of the
thora.x pale blue or orange, butl-colored below ; paraptera trapezoidal,
black, the cephalic margins and a spot below the lateral angles pale;
legs usually buff, the femora with rm indefinite dorsal brown line and
a row of spots, the tibiae with a faint dorsal line or row of dashes;

555

tarsi pale, darker at the apices ; wings with ten postnodal cross-veins
in the front wing and eight in the hind one; Mo arising near the fifth
postnodal vein in the front wing and between the fourth and fifth
or between the third and fourth, usually near the fourth, in the hind
wing.

Abdomen orange or blue and black ; dorsum of terga i-8 inclusive,
black, except interrupted basal rings on 3—7, lateral surfaces of one
and two, and the lateral margins of 3-8 ; all of tergum nine and the
lateral surfaces of the tenth orange or blue, the dorsum of ten being
black; anal appendages (Figs. 185,192) dark brown, the superiors
much longer than the inferiors, blunt at the apices, the lateral surfaces
convex, the mesal surfaces somewhat concave ; inferiors about half
as long as the superiors and subconical, the tips black and directed
mesad.

Female. — Color, pale blue or orange, and black.

Head similar to that of the male.

Thorax similar in all particulars to that of the male ; the orange-
colored females are, however, less frequent ; mesostigmal plates ( Fig.
214) long, the lateral margins rounded, and a diagonal pale stripe
crossing the plates.

Abdomen blue or orange, and black ; terga 1-9 with black, dorsal,
longitudinal stripes from the bases to the apices, the stripes widened
near the apex on 2-7 and narrowed on the ape.x of nine ; lateral surfaces
of all terga, basal rings on 3-7, and an apical ring on one, yellow or
bluish; all of segment ten yellow or blue; sterna 3-8 black; anal ap-
pendages of the usual form ; ovipositor with the lateral valves pale
and serrated on the ventral margins, the prostyles brown.

Measurements

Length, $ 34-35 mm.

Length, 5 34-35 mm.

Length of abdomen, S 26-28 mm.

Length of abdomen, 2 28 mm.

Length of hind wings, 3 17 mm.

Length of hind wings, 2 20 mm.

Width of hind wing.s, <J '. . .3.5 mm.

Width of hind wings, 2 4 mm.

One of the commonest species in Illinois, occurring in all localities.
Next to Ischnura verticalis it may be considered as the most abundant.

The nymphs may be collected in slow streams, permanent ponds,
or lakes, and prefer the clear water. They emerge in central Illinois

556

as early as the tenth of May and the greatest number of adults appear
on the wing about June I. The latest emergence which is recorded
is one on June 25, 1915. This gives a period of emergence of at least
a month and a half.

Specimens have been seen from Havana, Lake \"illa, Muncie,
Peoria, and Urbana.

Enahagma traviatum Selys

.Yyniph. — Color, very dark brown.

Head about one-third as long as broad, dark in color; caudo-
lateral margins projecting caudad, studded with short setae; antennae
very slender, the first two segments with setae and of much greater
diameter than the remaining ones, the third segment longest, the
second decidedly shorter than the first ; labium extending slightly cau-
dad of the first pair of coxae ; mental setae two, with sometimes a rudi-
mentary third, lateral setae four; marginal setae of the median lobe
six or seven.

Thorax : lateral portions of the prothorax and the metapleura
darker than the dorsum of the thorax; legs slender, the coxae dark
brown, femora almost wholly devoid of setae, but with very distinct
preapical brown rings ; tibiae with setae which are rather closeh- set,
especially towards the apices ; tarsi pale.

Abdomen brown, darker immediately above and below the lateral
keels ; cuticle with a few minute setae, but lacking minute black spots
entirely; lateral keels feebly developed and without heavy setae, there
being instead a few setae near the apices of the keels; gills (Fig. 55)
rather narrowly lanceolate, the median gill entirely without heavy
setae on the dorsal margin ; lateral gills with the ventral marginal row
of setae extending one-half or less of the length of the gills ; basal
two-fifths or one-half of the gills uniform dark brown, the pigmented
area followed by a broad white or clear band extending from margin
to margin and including the axes; beyond the clear portions there are
frequently one or two brown transverse stripes, the apex of the gills
being without pigment; ovipositor extending caudad to the apex of
the tenth sternum, the ventral margins of the lateral valves with one
or two heavy setae and a number of hairs.

Measxirements

Length 11 mm.

Length of abdomen 8 mm.

Length of gills 6 mm.

Width of gills 1 mm.

557

Length of metathoracic wing-cases. . .3.5 mm.

Length of median lobe 2 mm.

Width of median lobe 5-1.3 mm.

Adult; Male. — Color, pale blue and black.

Head blue and black ; labium buff, the median lobe with a broad
median cleft; distal segment of the labial palpi pale; antennae brown,
the first segment sometimes witli the ceplialic half blue ; postclypeus
blue with a small black spot on eacli side ; anteclypeus blue ; labrum blue
with a black dorso-mesal spot; exposed portion of the mandibles, their
trochantins, genae, and the front from the f ronto-clypeal suture dorsad
to the median ocellus, blue ; lateral ocelli with small blue spots ventrad
of them, and a similar spot between the ocelli ; remainder of the front
black; postocular spots very large, forming equilateral triangles and
occupying most of the dorsal portion of the occiput, the spots bounded
caudad by a very narrow black band and separated from the com-
pound eyes by a band of similar width; tlie narrow stripe caudad of
the ocellar area is indistinct; occiput and postgenae pale blue.

Thorax blue and black ; pronotum blue and black, the cephalic
lobe with a transverse line of blue on the caudal margin, the median
lobes with elongate blue spots, contiguous on the meson, and semi-
crescentic spots of the same color ; proepimera and proepisterna brown
or pale ; mesothorax with the narrow black stripe covering the dorsal
carina but frequently divided there by a line of brown; black stripe of
the mesopleural suture reduced to a line on the suture; mesinfraepi-
sterna with black crescentic marks on the dorsal borders; remainder
of the pleura blue with the exception of small spots on the interpleural
folds and metapleural sutures adjacent to the wing bases ; postcoxal
areas pale ; paraptera black, crescentic, the cephalic margins and lateral
angles blue; legs striped, pale blue or buff and black, the coxae and
trochanters blue, the femora blue with broad dorsal black stripes which
are frequently interrupted at the base by a pale spot ; tibiae pale blue and
buff with a short dorsal black stripe or none, the tarsi pale, black at the
tips ; claws deeply bifid and black at the tips ; wings with ten postnodal
cross-veins in the front wing and eight in the hind one; Mj arising
between the fourth and fifth postnodal cross-veins in the front wing
and between three and four in the hind one; stigma small, subellip-
tical, and surmounting less than a single cell.

Abdomen blue and metallic black, the dorsum of the first tergum
with a small black basal spot about half the length of the tergum; sec-
ond tergum with a black, apical, shield-shaped spot, the spot extending
to the cephalic margin and narrowed at this point to a line on the me-

558

son; terga 3-7, inclusive, with longitudinal black stripes widened subap-
ically and narrowed basally, the lateral margins t)f the terga pale ; terga
eight and nine usually entirely blue, the eighth sometimes with a basal
spot on the dorsum; tenth terguni black; anal appendages (Figs. 199,
206) short and black, the superiors slightly longer than the inferiors
and appearing slightly knobbed at the apices when seen in lateral pro-
file; viewed from above, the superior appendages are seen to have
broad basal lobes which are often contiguous on the meson; inferior
appendages short, subconical, and directed uhliciuely dorsad; first
sternum pale, 3-8 black, the tenth pale.

Female. — Color similar to that of the male.

Head similar to that of the male except that the front is paler
and the spots ventrad of the lateral ocelli are larger and connect with
the pale color of the ventral portions of the front; the black borders
of the postocular spots are narrower than those of the male.

Thorax: dorsal stripe divided by a line of brown on the carina;
mesostigmal plates pale blue, the lateral angles elevated (Fig. 214),
and a sinuate dark stripe on the supracpisterna just caudad of the
plates; mesopleural suture with a distinct spot cephalad of the wing
bases and the black of the infraepisterna reduced to narrow dorsal
lines; postnodal cross-veins of the front wing ten to eleven, of the
hind wing nine to ten.

Abdomen: dorsum of the first tergum with a black basal spot,
2-7, inclusive, with narrow dorsal longitudinal stripes, widened sud-
denly near the caudal margins and narrowed to the meson near the
cephalic margins; tergum eight blue with a narrow dorsal stripe ex-
tending a little over half the length of the tergum from the base,
(Fig. 94) ; ninth and tenth terga blue; anal appendages of the usual
form ; ovipositor with broad, blue, lateral valves ; first and second
sterna pale, with black mesal lines, 3-8, inclusive, black.

M€asur€me7its

Length, S 31 mm.

Length, 9 31 mm.

Length of abdoinou, S 25 mm.

Length of abdomen, 9 25 mm.

Length of hind wings, S 17 mm.

Length of hind wings, 9 18.5 mm.

Width of hind wing.s, $ 3.25 mm.

Width of hind wings, 9 3.5 mm.

559

This species was collected at Carbondale, 111., June, 1915, and
was reared at that time. It has not been reported elsewhere in the
state but doubtless occurs about glacial lakes and ponds.

The nymph differs from that of exsnlans chiefly in the darker
color. In all the specimens studied the labium has only two men-
tal setae as compared with three in cxsulaus. The gills show con-
siderable difference in the shape and pigmentation, particularly of the
apical portions.

The adult is most closely related to exsnlans, but both sexes may
be distinguished by the reduced amount of black on the mesopleural
suture, the greater amount of blue on the front, and the exceedingly
large postocular spots.

Genus Nehalennia Selys

The nymph of the only representative of this genus occurring in
Illinois is characterized by its peculiar type of gills, in which the
tracheae are much more numerous near the widest portion of the gill
than elsewhere.

The dominant color of the adult is metallic green or bronze, the
mesepisterna being entirely without pale stripes and the pronotum
without pale spots. The female has the caudal lobe of the pronotum
trilobed and the eighth sternum is without the ventral apical seta.
The sternites at the base of the cephalic pair of gonapophyses arc
minute and scarcely visible.

Nehalennia IRENE Hagen

Nymph. — Color, brown or green.

Head oval in outline, the caudo-lateral angles with but few setae ;
antennae with the second segment longer than the first, the second
segment and proximal third of three dark in color ; labium, when
folded, extending nearly to the mesocoxae, with a single large mental
seta and a smaller one alongside ; lateral setae five, and the lateral
margins of the median lobe with about five small setae.

Thorax : femora and tibiae with rows of sparsely placed setae,
the preapical rings of brown on the femora very indistinct ; apical
tibial scales present; wing-cases extending nearly to the apex of the
fourth abdomipal segment.

Abdomen slender, with feeble lateral keels, the cephalic two or
three without setae, the caudal ones with not more than six or seven;
cuticle of the abdomen with small whitish spots on a darker back-
ground; gills (Fig. 61) much broader beyond the middle, the lateral

560

gills with ten to twelve black cuticular spots on the margins and a
distinct arcuate cross-band just beyond the middle ; tracheal branches
much more numerous bcNond the middle of the gill; marginal setae
large and widely separated, the ventral row of the lateral gills ex-
tending about half the length of the gill from the base and the distal
setae much farther apart than the proximal ; ovipositor usually ex-
tending beyond the apex of the tenth segment.

Measurements

Length 10-11 mm.

Length of abdomen 8 mm.

Length of gills 4-4.5 mm.

Width of gills 1 mm.

Length of median lobe 1.5-1.7 mm.

Width of median lobe 1.25 mm.

Described from three specimens obtained from Dr. E. ]\I. Walker,
and labeled Toronto, Ont., May 31, 1913.

Adult; Male. — Color, metallic green and pale blue.

Head metallic green above, buff below ; median lobe buff, the cleft
large and rounded at the base; distal segments of the labial palpi dark
at the tips ; antennae black, the second segment with a pale ring at
the niidclle; postclypeus shining black, tlie anteclypeus buff; labrum
pale yellow with a dorsal, transverse, shining black stripe about one-
third the width of the piece ; exposed portions of the mandibles, the
trochantins, genae. and the front from the fronto-clypeal suture dorsad
to the antennal fossae, shining yellow ; remainder of the front, vertex,
and a large portion of the occiput, metallic green; postgenae black,
with a pale stripe beneath the compound eyes which is continuous with
the yellow of the genae ; compound eyes brown.

Thorax metallic green and pale blue ; pronotum metallic green
without paler spots, the margin of the caudal lobe entire ; proepimera
buff-colored ; dorsal carina and the mesoplcural suture lined with
I)lack; mesosupraepisterna and tlie mesepimera except the cephalo-ven-
tral shoulders metallic green ; dorsal margin and about the ventral half
of the mesinfraepisterna pale, the remainder metallic green ; remainder
of the mesopleura and metaplcura except a green triangle adjacent
to the wing base on the metepimera, buff or jjale blue; postcoxal
I'.reas buff or pale blue ; legs pale, striped with black ; coxae and tro-
chanters pale, all the femora with dorsal stripes extending from the
apices nearly to the bases, antl the front femora with a short cephalo-

561

ventral stripe including the cephalo-ventral row of setae ; tibiae with
long dorsal stripes extending from a point slightly distad of the femora
to near the apices of the segments; tarsi and claws pale except at
the apices; wings short, the postnodal cross-veins ten in the front
wing, nine in the hind wing; Mo arising between the fourth and fifth
postnodal cross-veins in the front wing and between three and four
in the hind wing.

Abdomen metallic green and pale blue ; terga 1—7, inclusive,
metallic green above, with broad, lateral, pale stripes on one and two,
and narrow lateral stripes and interrupted basal rings on 'y-'j; eighth
tergum green on the dorsum except at the apex, where there is a tri-
angle of blue, the lateral angles of which are continuous with the
broad blue stripes on the lateral surfaces ; ninth and tenth terga blue
with green basal triangles on each side of the meson; anal appendages
(Figs. 159,160) with the superiors small and tuberculate, the inferiors
much larger than the superiors and toothed at the apices.

Female. — Color, metallic green or bronze, and yellow.

Head similar to that of the male except that within the dark
area of the front there is a pale spot ventrad of each antennal fossa.

Thora.x differing from that of the male in having the caudal
lobe of the pronotum emarginate on each side of the meson, the
piece being trilobed ; the mesostigmal plates (Fig. 182) have the mesal
margins strongly elevated and projecting dorsad ; the front wings have
nine to ten postnodal cross-veins, the hind wings usually nine.

Abdomen with terga 1—8, inclusive, greenish bronze, the lateral
margins pale; ninth tergum green above, with an apical blue triangle
and blue lateral stripes ; tergum ten blue, with two small green tri-
angles at the base ; anal appendages of the usual type ; ovipositor, in-
cluding prostyles, extending beyond the apices of the anal appendages,
the prostyles dark.

Measurements

Length, S 27 mm.

Length, 9 26 mm.

Length of abdomen, S 21.5 mm.

Length of abdomen, 9 '. . .21 mm.

Length of hind wings, S 15 mm.

Length of hind wings, 2 15 mm.

Width of hind wings, S 4 mm.

Width of hind wings, 9 4 mm.

The species is apparently limited to the northern third of the
state. It was abundant at Lake Villa, July 13, 1915. and was also
taken at Freeport July 8, 191 5.

562

Genus Amphiagriox Selys

Tlie nymph of the only species of the genus known to occur
in lUinois is easily distinguished from other genera by means of the
projecting caudo-lateral angles of the head. The gills are without
cuticular pigment and are decidedly ovate in shape.

The adults are red or brown in color. The stigma of both front
and hind wings is turned obliiiuely to the long axis of the wing and
the width is much greater than its length. The eighth sternum of
the female possesses a long seta, and the sternites at the base of the
cephalic pair of gonapophyses are small but visil)lc with moderate
magnification. The superior anal appendages of the male are much
sliorter than the inferiors and tlie paramcrcs of the ninth sternum do
not reach the apex.

Amphiagriox s.mcium (Burmeister)

Nympli.-— Color, dark brown.

Head pentagonal and characterized by having the caudo-lateral
angles projecting strongly and forming a short blunt tubercle ; an-
tennae composed of seven segments, the distal segments being short
and similar to those of the nymphs of the genus Argia ; laliium broad,
when folded extending to the metacoxae, the median lobe with three
or four mental setae and six lateral setae, and the margins of the
median lobe with ten to twelve setae.

Thora.x i)rown; legs without brown rings ami unifcirm in color;
femora indi.stinctly carinate ; tibiae with rather closely set slender
setae; wing-cases extending caudad to the fourth or fifth abdominal
segment.

Abdomen thickset, the lateral keels absent or feebly developed
arid without setae; ovipositor of the female nearly reaching the apex
of the tenth segment in full-grown nymphs; caudal gills (Fig. 59)
transparent, ovate-lanceolate, the apices gradually narrowed to a sharp
point; margins of the gills setose fnmi the jjroximal to the distal end,
the setae placed closely together and increasing in length towards the
apices; tracheal trunks sometimes subdividing and forming a number
of large branches near the proximal fourth of the gill.

Mcasurcmaiis

Length 11-14 mm.

Length of abdomen 7-10 mm.

Length of gills 4.5 mm.

Width of gills 1.5 mm.

563

Length of metathoracie wing-cases. . .3.5 mm.

Length of median lobe 1.75-2.0 mm.

"Width of median lobe 1.25-1.5 mm.

Described from a single specimen taken at Muncie, III., April 25,
1914, and several specimens obtained from Dr. J. G. Needham, col-
lected at Galesburg, 111., June 3, 1897.

Adult; Male. — Color, very dark brown and deep orange-red.

Head black or dark above, pale below ; labium pale, the median
lobe subtriangular, the cleft shallow and broad at the base ; antennae
dark brown, the first two segments subequal in length, the first with
a pale apical ring; postclypeus dark brown; anteclypeus, labrum, ex-
posed portions of the mandibles, their trochantins, genae, and a trans-
verse stripe on the front above the fronto-clypeal suture, pale buff,
the pale area of the front extending dorsad along the margins of the
compound eyes to the level of the antennal fossae ; remainder of the
front and vertex very dark brown, nearly black ; occiput and postgenae
pale.

Thorax dark brown to brick-red and yellowish buff; pronotum
dark ; proepimera also dark, nearly black ; dorsum of the mesothorax,
including the supraepisterna and the epimera and the caudo-dorsal
angles of the metepisterna, black or dark brown; remainder of the
meso- and metathorax yellowish red ; intersternum projecting ventrad,
conspicuous from the side, and provided with long black setae ; legs
yellowish buff, the coxae and trochanters yellowish, the femora slightly
darker above but without distinct stripes ; tibiae entirely pale and the
tarsi pale except at the tips; femora with rounded dorsal carinae;
wings with ten postnodal cross-veins in the front wing and about
eight in the hind wing; Mo arising between the fourth and fifth post-
nodal cross-veins in the front wing and between the third and fourth
in the hind one ; stigma reddish, small, surmounting a single cell.

Abdomen red and black; terga 1-6 dull red, with the exception
of small caudo-lateral black spots on the dorsum of 1-6 inclusive,
and subapical spots on five and six ; terga 7—10 black on the dorsum,
the lateral margins and a broad basal ring on seven reddish ; anal
appendages (Figs. 174,178) reddish, the superiors shorter than the
inferiors, flat and the dorsal surface depressed ; inferiors longer, acute,
subconical, the tips directed dorso-mesad ; apical margins of the tenth
tergum emarginate on the dorso-meson and depressed at this point,
forming a deep rounded pit.

Female. — Color in general similar to that of the male but usually
considerably lighter.

564

Head similar to that of the male but lighter in color.

Thorax buff, and not blackish on the dorsum as in the male;
mesostigmal plates as shown in Figure i8i.

Abdomen : terga 1-4 red ; terga 5-7 red with two black spots on
each near the caudal fourth ; terga eight and nine with two longitudinal
black stripes extending from the cephalic margins to within a very
short distance of the caudal margins; tergum ten pale buff; sterna
i-io buff; eighth sternum with a long seta; ovipositor with broad,
buff, lateral valves, the ventral margins serrate ; prostyles short, brown.

Measurements

Length, $ 26 mm.

Length, 9 26 mm.

Length of abdomen, S 21 mm.

Length of abdomen, 9 21 mm.

Length of hind wings, $ 16 mm.

Length of hind wing.s, 9 16 mm.

Width of hind wings, S 3.5 mm.

Width of hind wings, 9 3.5 mm.

Adults have been collected at Urbana during the latter part of
May and early part of June, but the species has at no time appeared
in great alnmdance, and attempts to secure the nymphs from this
locality have failed.

Genus Chromagrion Needham

The nymphs of this genus are characterized by the projecting
caudo-lateral angles of the head and the extremely long and slender
gills, which are without conspicuous marginal setae. The median lobe
of the mentum is provided with mental setae and the proximal seg-
ments of the laliial palpi have a single sharp fixed hook and a blunt
process with teeth at the apex. The lateral keels are not well developed
and are without heavy setae. ,

The adult is characterized by the absence of postocular spots, by
the long, somewhat forcipate, anal appendages of the male, and by
the peculiar formation of the pronotum of the female — as shown in
Figure 170. The parameres of the male extend to the apex of the
ninth sternum.

The genus is represented in North America by a single species.

565

Chromagrion CONDITUM (Hagen)

Nymph. — Color, dark brown.

Head half as long as wide, the caudo-lateral angles projecting
strongly; labium, when folded, extending caudad to the procoxae;
mental setae three and sometimes a small fourth; lateral setae five;
proximal segment of the palpus with a distinct hook at the apex of
the mesal process and the median lobe with a slight notch at the apex.

Thorax : femora with two dark rings and a double row of setae
on the ventral surfaces; tibiae with a single basal ring of brown;
wing-cases reaching caudad to the fifth abdominal segment.

Abdomen slender; lateral keels feebly developed and without
setae; gills long and slender, widening gradually to near the apices,
then suddenly contracted, the margins setose, the setae far apart and
increasing in size distad ; color of gills uniform dark brown, except
that the tips are light; indistinct blotches of darker pigment occur
around the margins of the gills; smaller tracheae transparent and
indistinct.

Measurements

Length 17 mm.

Length of abdomen 10 mm.

Length of gills 6 mm.

Width of gills 1 mm.

Length of median lobe 2 mm.

Width of median lobe 6-1.6 mm.

Described from fragments of several exuvia obtained from Dr.
J. G. Needham, and the description completed from data given by
Needham in his description of the species ('03: 247).

Adult; Male. — Color, blue, black, and yellowish orange.

Head black and dark brown and buff ; mouth-parts yellowish, the
labium pale, the median lobe subtriangular in outline, the cleft broad
and deep ; labial palpi pale, the distal segment also pale ; antennae nearly
black, the first segment nearly as long as the second ; postclypeus black,
the anteclypeus, labrum, mandibles, their trochantins, genae, and the,
front above the clypeus to the level of the antennal fossae, greenish
blue ; remainder of the vertex, occiput, and postgenae black.

Thorax black and blue, the pronotum largely black, the cephalic
lobe, a small spot on the lateral margins of the median lobes, and the
lateral margins of the caudal lobe, pale; proepimera and pro-
episterna bluish green, the dorsal borders black; mesostigmal
plates long and triangular, the lateral angles pale ; mesepisterna with a

566

broad black stripe which, adjoining the wing bases, is exactly the width
of the two mcscpistcrna together, but contracts suddenly shortly
cephalad of this, and again aljout lialf-way to the cephalic margin of the
mesothorax ; niesinfraepisternuni with an indefinite black spot on the
cephalic border; caudal margins of the mesepimera and metepisterna
black, shining, the sclerites themselves pale blue; metepimera lemon-
yellow, the cephalic half of the ventral margins frequently dark; post-
coxal areas yellowish buff, lateral margins of the intersternum darker;
legs black and greenish buff, the coxae usually black on the cephalic
surfaces ; trochanters black on the dorsum, the femora with a broad,
shining black, dorsal stripe, which encircles the segment at the apex
and is narrowed basally on the front femora; femoral setae of the
front femora, seven and four in the two rows respectively; tibiae
pale buff, with a darker stripe on the ventral surfaces between the
rows of setae, the tips dark ; tarsi shining black ; wings with eleven
postnodal cross-veins in the front wing and ten to eleven in the hind
one ; stigma surmounting a single cell and much longer than broad.

Abdomen blue and black, the first tergum with a short basal
black spot on the dorsum and latero-cephalic angles ; terga 2—6, in-
clusive, blue with cephalo-lateral spots of black ; second tergum with
an apical shield-shaped spot and an apical ring; terga 3-6 with dorsal
longitudinal stripes, narrowed to a line at the cephalic margins and
widened to the lateral margins at the caudal end of the segment;
terga eight and nine blue, with narrow lateral stripes on the lateral
margins and mesal stripes from the base to the distal fourth and
small spots on each side of the distal extremity of the lines; tenth
segment entirely black except the small blue spots on the dorsum, one
on each side of the meson; first sternum pale, with a black median spot,
2-9 black; anal appendages (Figs. 102,106) black, the superior ap-
pendages longer than the inferiors, slightly swollen at the apices, and
the mesal surfaces densely hairy; inferiors short, pointed at the tip,
the dorsal surface flat, the ventral surfaces conve.x.

Female. — Color: tlie blue <>f llie male is replaced by 3'ellowish
buff; the yellow is the same as that of the male.

Head similar to that of the male.

Thora.x : (ironotum curiously modified, the caudal margins of
the caudal lobe not continuous (Fig. 170) and the median lobe with
a flat lateral i)rojection on each side ; jiroepimera entirely pale ; meso-
stigmal plates broad, the caudal margins convex, the lateral angles
more or less acute, and the latero-caudal margins slightly elevated.

Abdomen buff and black, the first tergum with a black basal spot
and a cephalo-lateral spot on each side ; dorsum of the second tergum

I

567

with a broad black band from the base to the apex which is widened
subapically, and a narrow apical ring ; terga 3-7 with small dark spots
near the cephalo-lateral angles, broad dorsal longitudinal stripes, nar-
rowed at the base but not to a line, and widened at the apex but not
reaching the lateral margins of the sclerites except on terga five, six,
and seven; terga 7-10 with pale lateral margins and black dorsal
stripes, the stripes narrowed at the caudal end; anal appendages of
the usual type ; ovipositor short, brown, the prostyles short and blunt,
the eighth sternites at the base of cephalic pair of gonapophyses
large and subtriangular ; sterna 2-7 black, the eighth with a black
median line but without an apical spine.

Measurements

Length, S 35 mm.

Length, 9 36 mm.

Length of abdomen, S 29 mm.

Length of abdomen, 9 30 mm.

Length of hind wings, $ 21 mm.

Length of hind wings, 9 22 mm.

Width of hind wings, S 4 mm.

Width of hind wings, 9 4 mm.

Described from a number of specimens in the collection of Mr.
E. B. Williamson. Reported from northern Illinois by Needham

('03:247)-

Genus Ischnura Charpentier

The nymphs of this genus have gills with long tapering points
and one or more arcuate cross-bands. The labium is moderately
broad and the median lobe possesses four or five setae and five or
six, usually six, lateral setae.

The adults may be distinguished from other genera by the pres-
ence of postocular spots, by the origin of vein Mj, which is between
the third and fourth postnodal cross-veins in the front wing and be-
tween the second and third in the hind wing, and by the presence in
the males of a short apical projection of the dorsum of the tenth
tergum, which is, however, not as long as the segment. The sternites
at the base of the cephalic pair of gonapophyses of the female are
very small and do not project beyond the caudal margin of the large
basal sternite of the eighth segment. The parameres of the male do
not extend caudad to the margin of the ninth segment and the anal
appendages are short, the superiors being about as long as, or shorter
than, the inferior appendages.

568

Key to Species

NYMPHS

a. Gills with four distinct arcuate cross-bands and a })lot('li on the tip
of the gill ; dorsal niarfjinal setae of the median gill extending one-
third the length of the gill from the base ; lateral setae of the labium,

five posita.

aa. Gills with one or two cross-bands or none, never with four; dorsal
marginal setae of the median gill extending one-half the length of the
gill from the base; lateral setae of the labium usually six. .verticalis.

ADULTS

a. Mesopleural pale stripe of the supraepisterna interrujited at the caudal
third and fonning a distinct exclamation point ; eighth sternum of

the female with a long spine posita.

aa. Mesopleural pale stripe of the suj)raei)isterna not interrujited at the
caudal third and not forming a distinct exclamation point ; eighth
sternum of the female without a long spine.

b. Seventh tergum with more or less blue on the dorsum. . . .kellicotti.
bb. Seventh tergum black on the dorsum verticalis.

IscHNURA KELLICOTTI Williamson

Nymph. — Unknown.

Adult; Male. — Color, blue and black.

Head blue and black; labium pale buff, the median lobe subtri-
angular; labial palpi broad, the second segment pale; antennae dark
brown, with a small i)ale blue spot on the condyle of the scape; post-
clypeus black, anteclypeus blue ; labrum blue except a black dorsal
marginal line; exposed j)ortions of the mandibles, their trochantins,
genae, and the front above the fronto-clypeal suture to the antennal
fossae, blue; the blue area of the front is divided by a short black line
on the meson and the blue color extends dorsad above the genae to
the antennal fossae ; remainder of the front and the vertex black ;
postocular spots large and Ijlue and connected with the blue of the
occiput; occiput and postgcnae except medium-sized I)lack spots on
each side of the occipital foramen, pale blue.

Thora.x blue and black; pronotum largely black, the cephalic lobe,
caudal margin of the caudal lobe, and four small spots on the median
lobe, near the meson, blue ; proepimera blue and black, the caudal
half being largely blue; mcsostigmal plates with blue lateral angles;
mesothorax with black sui)raepisterna which possess narrow longi-
tudinal blue stripes, the stripes narrowed conspicuously at the middle

569

and widened at both ends but not extending caudad to the paraptera;
dorsal half of the mesepimera black, the black stripe covering that
portion suddenly widened by a ventral projection just caudad of the
mesinfraepisternum; mesinfraepisterna black except the caudo-ven-
tral angles; remainder of the pleura blue, the interpleural fold and
the metapleural suture, however, lined with black ; postcoxal areas
mostly pale; legs blue and black; coxae largely blue, the cephalic sur-
faces sometimes spotted with black ; trochanters blue, black above ;
femora with broad dorsal stripes, blue beneath ; tibiae, tarsi, and claws
brown and without stripes ; wings with eight or nine postnodal cross-
veins in the front wing and seven in the hind wing ; stigma subelliptical,
black or blue in the front wing, pale in the hind wing; Mo arising
between the third and fourth postnodal cross-veins in I)oth wings.

Abdomen black, blue, and buff ; first tergum blue with the cephalic
half black; second, blue with a broad black lateral stripe on each side
and a narrow apical ring, the stripes extending from the base of the
segment to the caudal third and the two uniting on the meson at the
caudal ends ; terga 3—6 black, with narrow, bkie, interrupted basal
ring and lateral marginal stripes ; seventh tergum black with pale
lateral stripes and a blue apical spot on the dorsum ; eighth and ninth
terga blue with broad, black, lateral stripes ; tenth tergum black, oc-
casionally with indefinite blue dorsal spots ; anal appendages dark, the
superiors broad, laterally compressed and the ventro-mesal angles hook-
like ; inferiors slightly longer than the superiors, subconical, the tips
black ; sterna i-io black.

Female. — Color similar to that of the male.

Head similar to that of the male except that the pale area of the
front is not divided by the mesal black line.

Thorax: the blue of the male is replaced by buff; pale spots of
ihe pronotum large and occupying nearly the whole of it; pale stripe
of the mesosupraepisterna extending caudad to the paraptera; legs
similar to thoge of the male, but usually paler in color; stigma of both
wings brown.

Abdomen : first tergum similar to that of the male ; second, blue,
with a dorsal black spot near the caudal margin- and the lateral mar-
gins pale; terga 3-6 black with pale lateral margins; terga 7-10 pale
blue with black lateral margins; anal appendages of the usual type;
ovipositor with broad lateral styles.

Measurements

Length, 3 32 mm.

Length, 9 31 mm.

570

Lciif^th of abdomen, i 25 mm.

Length of alidomcn, 9 25 mm.

Length of hind wings, 3 .27 mm.

Length of hind wings, 9 28 mm.

Width of hind wings, 6 3.5 mm.

Width of hind wings, 9 3.5 mm.

This species has not been taken in IIHuois, but has been collected
in Indiana by Mr. Williamson, and the above description has been
made from specimens in his collection.

IscHXUR.\ I'OSiTA (Hagen)

Nymph. — Color, usually dark brown.

Head oval or elliptical in outline, the caudo-lateral angles not pro-
jecting and with only a few setae; antennae of the usual form, the
hrst two segments dark in color, the second light at the tip; labium
extending between or slightly caudad of the procoxae; mental setae
four and sometimes a small fifth on each side ; lateral setae five ; lateral
marginal setae of the median lolje four.

Tiiorax about ecjual in diameter throughout; femora with rows
of setae which become heavier towards the apices ; tarsi pale, the apices
of the third segments brown; metathoracic wing-cases extending cau-
dad to the fourth abdominal segment.

Abdomen : cuticle provitled with numerous black spots usually
bearing a single minute seta; lateral keels without setae except those
of the caudal segments ; gills lanceolate ( Figs. 64, 66) , broadest beyond
the middle, usually with four crescentic brownish bands of wiiich the
apical ones are somewhat paler than the proximal, the median gill w ith
a dorsal row of about fourteen setae extending one-third the length
of the gill from the base ; ovipositor extending to the apex of the tenth
abdominal segment.

Measurements

Length 1L5 mm.

Length of abdomen '7.5 mm.

Length of gills 5-5.5 mm.

Width of gills 1.6 mm.

Length of metathoraeie wing-cases. .3.0 mm.

Length of median lobe 2.0 mm.

Width of median lobe 5-1.6 mm.

The nymph is very closely related to vcrticalis but may be sep-
arated from the latter by means of- the shape and figuration of the

I

571

gills. The lateral setae of the labium do not often exceed five, whereas
ihere are usually six in Z'crticalis.

Adult; Male. — Color, black and sulphur-yellow.

Head black and yellow ; mouth-parts "buff, the median lobe sub-
triangular; palpi narrow, the distal segment pale; antennae uniform
dark brown, the second segment considerably longer than the first;
postclypeus shining black ; anteclypeus pale, labrum pale, with a trans-
verse dorsal black stripe which has a slight ventral projection on the
meson; remainder of the labrum, exposed portions of the mandibles
and their trochantins, genae, and the front dorsad of the fronto-clyp-
eal suture to the level of the antennal fossae, shining yellow; re-
mainder of the front and vertex black, the postocular spots yellow and
circular; a short yellow line caudad of the ocelli ; postgenae and occiput
yellow.

Thorax black and yellow ; pronotum black except the cephalic
lobe, which is yellow; caudal lobe with yellow spots on the lateral
angles ; mesostigmal plates with large oval yellow spots ; mesosupra-
episterna with short yellow stripes and spots adjacent to the parap-
lera, the t\yotogether forming an exclamation point on each side of
the dorsal carina; black stripe covering the mesopleural suture on
each pleuron contracted near the wing bases ; dorsal half of the m.es-
infraepisterna and a stripe on the metapleural sutures black, the re-
mainder of the metathorax and tiie postcoxal areas yellow ; legs black
and yellow, the coxae, trochanters, and femora pale, the femora with
a dorsal stripe on each from base to apex, the stripe widened subapi-
cally ; tibiae with a dorsal black stripe from base to apex which fades
into brown towards the apex ; tarsi and claws pale, darker at the tips ;
wings short, the postnodal cross-veins six to eight and M2 arising
between the third and fourth postnodal cross-veins in the front wing
and between the second and third in the hind wing.

Abdomen black and yellow; terga i-io dull black with the excep-
tion of a narrow basal ring on segments 3-7, the stripes narrowed
conspicuously on two and widened on the apices of segments 3-6
inclusive ; lateral margins of all terga pale yellow ; sterna 3-8 lined
with black on the meson ; apex of the tenth tergum with a mesal eleva-
tion at the apex, the elevated portion forming- two small tubercles;
anal appendages (Figs. 173,177) small, orange, the superiors large
and blunt and bent ventrad, the inferiors also large, blunt, and bifur-
cate, the arms feebly divaricate and the dorsal arm with a number of
heavily chitinized teeth.

Female. — Color, pale blue and black.

Head similar to that of the male except that the postocular spots
are blue.

572

Thorax pale blue and black, lackinjj the black stripes on the meta-
pleural sutures, and the femoral l)lack stripes almost wanting or re-
duced to short subapical lines.

Abdomen with the pale and black markings similar to those of
the male; anal a])pendages of the usual type, the ovipositor with pro-
styles extending caudad to the apex of the anal appendages.

Measurements

Length, S 24 mm.

Lonfjth. 9 29 mm.

Length of abdomen, S 1!) mm.

Length of al)domen, 9 18-22 mm.

Length of hind wing.s, S 12 mm.

Length of hind wing.s. 9 13-16 mm.

"Width of hind wing.s. s 2f) mm.

"Width of hind wings, 9 2.5-3.5 mm.

A common species in soutliern and central Illinois, occurring in
the same localities where 'rcrtiailis is aliundant. The adults appear
usually somewhat later than Trrticcilis, and the earliest reared si)eci-
mens in my collection bear the date June I2, 191 5.

Specimens have been seen from Havana, Peoria, and Urbana.

ISCHNURA VERTICAUS (Say)

A'yvil^li. — Color, pale green, buflf, or dark brown.

Head broader than long, subelliptical, the caudo-lateral angles
with strong setae; .antennae with the first two segments and the prox-
imal third of tlu-ee dark, the remainder pale; first two segments sub-
equal, the third as long as the first two together; labium, when folded,
extending slightly caudad of the procoxae, with four or five mental
setae rmd six lateral setae, the lateral marginal setae of the median
lobe six or seven in number.

Thorax nearly ecjual in diameter throughout; front femora with
a strong row of setae on the cei)halic surface and all the femora with
preapical rings of l)rown ; tibiae with several rows of apical setae,
two of which extend f.ar proximad ; wing-cases extending cautlad to
the fourth al)dominal segment.

Alxlomen cylindrical and witii fecl)le lateral keels on segments
T-8, the margins .and ventral surfaces being thickly studded with short
setae; cuticle of the abdomen witli sm;dl dark spots from which minute
setae usually .arise, one to each spot; gills (Figs. 62. 65) with long

573

tapering points, the dorsal marginal setae of the median gill usually
extending nearly half the length of the gill from the base, the ventral
row of the same gill consisting of about seven strong setae, consider-
ably farther apart than those of the dorsal row; ventral marginal
setae of the lateral gills extending slightly farther from the base of
the gills than the dorsal row of the median gill ; pigment of the gills in
the form of one or two arcuate cross-bands near the middle of the
gill ; these, however, may be wanting ; ovipositor extending to the
middle of the tenth abdominal sternum.

Measiwemeiiis

Length 13-14 mm.

Length of abdomen 9-10 mm.

Length of gills 6-7 mm.

Width of gills 1-1.3 mm.

Length of median lobe 1.8 mm.

Width of median lobe 6-1.6 mm.

Adult; Male. — Color, black or dark metallic green and pale green.

Head black and yellowish green ; mouth-parts buff, the median
lobe of the labium subtriangular, the cleft short and acute at the pro.x-
imal end ; antennae black or very dark brown ; postclypeus black, shin-
ing; anteclypeus, labrum, exposed portion of the mandibles and
their trochantins. genae, and the front above the clypeus, yellow;
postocular spots large and subcircular; vertex, and front except the
stripe above the clypeus, dull black ; occiput black and greenish yellow.

Thorax greenish black and greenish yellow ; pronotum shining
black with a transverse yellow stripe on the cephalic lobe ; caudal lobe
of the pronotum with a distinct transverse carina; noto-epimeral suture
indistinct, the proepimera and episterna largely yellow; mesothorax
shining black with a yellow stripe just above the mesopleural suture;
ventral half and cephalic shoulder of the mesepimera yellow ; paraptera
trapezoidal, with a yellow spot just ventrad of the lateral angles, the
remainder black; mesostigmal plates black, the caudal margins ele-
vated and lined with yellow ; metathorax including the postcoxal areas,
pale green or yellowish; legs black and yellow, the coxae and tro-
chanters pale with some darker marks on the sutures; femora all with
a broad dorsal stripe, the tibiae with narrower dorsal stripes extending
from near the bases to near the apices ; tarsi and claws pale, dark at
the tips; wings short, the postnodal cross-veins seven to nine, and M,
arising between the third and fourth postnodal cross-veins in the front
wing and between the second and third in the hind wing.

574

Abdomen shining black or green, and yellowish green; dorsum
of terga 1—7, inclusive, shining black or green with narrow apical ring
on the first, interrupted basal rings on 3—6, and the lateral margins
of 1—6 yellow; dorsum of terga eight and nine blue, with short lateral
black stripes on each side abtnit half the length of the segment; tergum
ten black, the lateral margins pale, tlie caudal margin with a short
forked process on the meson; sterna 3-9 with a mesal line of black;
anal appendages (Fig. 168) short, the superiors flat and placed nearly
vertically ; inferiors longer, and with a dorsal, basal knob and a larger,
subconical ventral lobe.

Female. — Color, orange and black or entirely black.

Head similar to that of the male except that the yellowish green
markings are replaced with orange.

Thorax orange and black; pronotum with an orange spot on each
median lobe ; margin of the caudal lobe with orange spots ; mesostigmal
plates (Fig. 180) with caudal elevated margins orange in color; meso-
pleural pale stripe of the supraepisterna orange and much broader
than the pale stripe of the male; dorsal third and caudal margin of
the mesinf raepisterna black, the remainder pale orange ; metathorax
orange; legs orange and black, the femora entirely pale except at the
tips, the tibiae with the usual dorsal stripes.

Abdomen orange and black, the first two segments entirely pale
except a narrow ring on the caudal margin of the second ; terga three
orange with an apical spot and ring; dorsum of terga 4-8 black, with
pale basal rings on 4-6 and the apical third of eight also pale; terga
nine and ten indefinitely marked with black, there being an orange
spot and apical ring of orange on nine and a dorso-mesal line on the
same; lateral margins of all the terga orange; sterna 1-8, inclusive,
with a mesal black line, the eighth sternum with a heavy spine; anal
appendages of the usual type; the ovipositor with dark brown pro-
tyles and pale lateral valves.

In older specimens the orange color becomes black and pollinose
so that it is difficult to distinguish the species on the wing from some
of the Enallagmas which also have a tendency to become dark.

Measurements

Length, S 20 mm.

Length, 9 30 mm.

Length of abdomen, S 22 mm.

Length of abdomen, 9 23-24 mm.

Length of hind wings, S 14 mm.

Length of hind wings, 9 17 mm.

Width of hind wings, S 3.5 mm.

"Width of hind wings, 9 3.5 mm.

s

575

The commonest species in Illinois, occurring practically where-
ever there is enough permanent water for the nymphs to live. The
adults appear early in May and continue to emerge until September
and possibly later.

Specimens have been seen from Dubois, Carbondale, Golconda,
Havana, Lake Villa, Mahomet, IMuncie, Peoria, Urbana, and Vienna.

Genus Anomai^agrion Selys

The nymphs of this genus are characterized by their unusually
small size, by the presence of a very slender tip to the gills, and by
tlie absence of setae on the lateral keels.

The male adults are unique in having the stigma of the front
wing removed from the margin and in the possession of a long process
on the dorsum of segment ten. The sternites at the base of the cephalic
pair of gonapophyses of the female are wanting, and the parameres of
the ninth sternum of the male do not reach the apex of the segment.

Anomalagrion hastatum (Say)

Nymph. — Color, green or buff.

Head with the caudo-lateral angles rounded and without setae;
antennae with the first two segments dark brown, the remaining ones
light in color ; second segment about as long as the first or slightly
longer ; labium not extending caudad of the procoxae and about as
broad as long; mental setae four, lateral setae five.

Thorax narrower than the head ; legs without dark rings and with
few setae, the tibiae with the usual apical scales ; wing-cases extending
nearly to the fourth abdominal segment.

Abdomen uniform in color; lateral keels feebly developed and
without setae; gills (Fig. 60) lanceolate, with a long point; marginal
.-etae of the median gill consisting of a thick dorsal row, extending
about one-third the length of the gill from the base, and a scattered
ventral row at the base ; ventral marginal row of setae of the lateral
gills slightly longer than the dorsal row of the median gill ; ovipositor
extending to the caudal margin of the tenth abdominal sternum.

Measurements

Length 9.5 mm.

Length of abdomen 5.5 mm.

Length of gills 4.5 mm.

Width of gills 1.0 mm.

Length of median lobe 1.6 mm.

"Width of median lobe 0.5-2.0 mm.

576

Adult; Male. — Color, pale lemon-yellow and black.

Head lenion-yellovv and metallic black ; mouth-parts buff, the
median lobe with a wide cleft which is obtuse at the proximal end;
antennae dark brown except the proximal segment, which has a pale
stripe from the base to the apex ; ])ostclypeus shining black ; antcclypeus
pale ; labrum with a transverse black stripe on the dorsal margin, the
remainder yellow ; exposed portions of the mandibles, their trochantins,
the genae, and the front above the f ronto-clypeal suture to the antennal
fossae, yellow; remainder of the front and thevertex metallic bronze
with the exception of very small postocular spots, a small yellow
spot ventrad of the median ocellus, and a narrow yellow stripe caudad
of the ocellar area.

Thorax greenish yellow and metallic black; cephalic lobe of the
pronotum with a vellow transverse stripe ; median lobes metallic black ;
caudal lobe black with three short marginal dashes; noto-epimeral
suture indistinct ; dorsal carina of the mesothorax feebly developed,
the mesothorax largely black with a narrow yellow line just dorsad
of the mesopleural suture ; dorsal half of the mesosupraepisterna black ;
metepisterna and epimera yellow or buff; paraptera trapezoidal, the
cephalic margins with a pale line ; coxae pale yellow, the femora pale,
with dorsal black stripes widened distad ; tibiae pale, with short, prox-
imal, dorsal and ventral dark stripes, the tarsi and claws pale except
at the tips ; setae of the front femora few, about three in each row, the
distance between them much greater than their length ; wings (Figs. 82,
83) verv short; postnodal cross-veins six in tlie front wing and five in
the hind; RL arising near the third postnodal vein in the front wing
and between the second and third in the hind wing; stigma of the front
wing ovoid, remote from the margin, the stigma of the hind wing
rhomboidal and in contact with the margin of the wing.

Abdomen yellow and orange, the black confined to longitudinal
dorsal bands on tcrga 1—3 and six, the stripe on three and the one on
six being conspicuously widened subapically ; basal and apical black
spots present on the fourtli and fifth terga. ami a dorsal stripe on seven
which is about three-fourths the length of the segment ; the narrow
basal ring on segments 1-7 is interrupted on the meson in all except
the first; tenth tergum with a dorsal process about as long as the
segment and bifurcate at the apex; anal appendages (Figs. 166, 167)
small, the superiors bifurcate, and with a broad niesal lobe extending
caudo-ventrad and a conical lateral one projecting caudad; inferiors
conical, slightly longer than the superiors.

577

Female. — Color, orange and black or dark brown.

Head orange and black, differing from that of the male in having
the black of the postclypeus reduced to a dorsal line and that of the
labrum to lateral spots ; postocular spots wanting, the caudal margins
of the head with a broad orange stripe ; occiput and postgenae pale.

Thorax : prothora.x as in the male except that the black of the
pronotum does not extend as far onto the lateral aspect ; dorsal black
stripe of the mesothorax extending on each side of the dorsal carina
one-half the width of the supraepisterna; mesopleural suture with a
black line, the remainder of the thorax orange and buff; mesostigmal
plates as shown in Figure 164.

Abdomen orange, with narrow basal black rings on terga 2-4
inclusive, a longitudinal dark stripe on the caudal three-fourths of
five, similar stripes extending the full length of six, seven, and eight,
and two triangular spots at the base of the ninth; dorsum of the
tenth tergum with a short blunt projection; anal appendages short;
ovipositor long and extending caudad of the anal appendages; prostyles
short and blunt.

Measurements

Length, $ 23 mm.

Length, 9 24.5 mm.

Length of abdomen, S 17 mm.

Length of abdomen, 9 19 mm.

Length of hind wings, S 10.5 mm.

Length of hind wings, 9 14 mm.

Width of hind wings, S 1 mm.

Width of hind wings, 9 2-2.5 mm.

This species is rather more common in the southern half of the
state than in the northern. It appears on the wing as early as June 20
at Urbana, but has been taken at Carmi, June 14, 1915.

Bibliography

The following bibliography has been made as complete as possible
in literature dealing with the nymphs. The remaining portion is in-
tended to include the works referred to in the preceding pages and
also the more important systematic publications, such as monographs
and catalogues. To persons beginning a study of the Odonata, Mutt-
kowski's "Catalogue of the Odonata of North America" and Calvert's
''Progress in our Knowledge of the Odonata from 1895 to 1912"
should be considered indispensable. In these two works, most of the
literature appearing previous to 1912 is cited. A number of important

578

articles have appeared since that date, and an attempt has also been
made to include these in this bibliography.

NYMPHS

Backhoff, Paul

'lo. Die Entwicklung des Copulationsapparates von Agrion. Ein
Beitrag zur postembryonalen Kntwicklungsgeschichte der Odo-
naten. Zeit. wiss. Zool., 95 : 647-706, pi. 21.

Balfour-Browne, F.

'09. Life-history of the agrionid dragonfly. Proc. Zool. Soc. Lon-
don, 1909; 253-^85, pis. 21,, 24.

Bervoets, R.

'13. Sur le systeme tracheen des larves d'Odonates. Ann. Biol.
Lacustre, 6: 15-32, figs. 1-3.

Borner, C.

'09. Neue Homologien zwischen Crustaceen und He.xapoden. Die
Beissmandibel der Insektcn und ihre phylogenetische Bedeu-
tung. Archi- und Metaptcrygota. Zool. Anz., 34: 100-125.

Brimley, C. S.

'04. Xotc on duration of larval stage of Odonata. Ent. News,

15: 136.

Butler, Hortense

'04. The labium of the Odonata. Trans. Am. Ent. Soc, 30 : 1 1 1-
134, pis. 2-7.

Calvert, P. P.

'00. Moults in the Odonata. Entomologist, 33: 350.

'11. Studies on Costa Rican Odonata. Ent. News, 22:49-64,

pis. 2, 3.
'15. Studies on Costa Rican Odonata. Ent. News, 26: 385-395,

pis. 15-17-

Forbes, S. A.

'88. On the food relations of fresh-water fishes. Bull. 111. State
Lab. Nat. Hist, 2:485.

Qilson, G., and Sadones. J.

■96. Larval gills of Odonata. Trans. Linn. Soc. London. 25 : 413.

Hagen, H.

'80. Essai d'un svnopsis des larves des Caloptervgines. Ann. de
la Soc. Ent. de Belgique, 23 : LXV-LXVIL

579

Heymons, R.

'96. Grundziige der Entwickelung und des Korperbaues von Odo-

naten und Ephemeriden. Anhang zu den Abhandl. Konigl.

Preuss. Akad. Wiss. Berlin, 1896. 66 pp., pis. i, 2.
'04. Die Hinterleibsanhange der Libellen und ihrer Larven. Ann.

k.k Naturhist. Hofmus., 19: 21-58, pi. i.

Kennedy, C. H.

'15. Notes on the life history and ecology of dragonflies (Odo-
nata) of Washington and Oregon. Proc. U. S. Nat. Mus., 49 :

259-345-

Lucas, W. J.

'12. Early stages of British Odonata. Rep. Lancash. Ent. Soc,

35: 17-24-

Lyon, Mary B.

'15. The ecology of the dragon-fly nymphs of Cascadilla Creek.
Ent. News, 26: 1-15, pi. i.

Needham, J. G.

'03. Life histories of Odonata, suborder Zvgoptera. Damsel

flies. Bull. N. Y. State Mus., 68: 2 18-279,' pis. 11-19.
'11. Descriptions of dragonfly nymphs of the subfamily Calop-

teryginae. Ent. News, 22: 145-154, pis. 4, 5.
'iia. Notes on a few nymphs of Agrioninae (order Odonata) of

the Hagen collection. Ent. News, 22: 342-345, pi. 11.

Pierre, I'Abb'e

'04. Sur I'eclosion des oeufs de Lcstcs z'iridis. Ann. Soc. Ent.
France, 73 : 477-484, pi. 4.

Riley, C. F. C.

'12. Observations on the ecology of dragon-fly nymphs : reactions
to light and contact. Ann. Ent. Soc. Amer., 5 : 273-292.

Ris, F.

'09. Odonata. Die Siisswasserfauna Deutschlands, Heft 9.

Rousseau, E. .

'09. fitude monographique des larves des Odonates d'Europe.
Ann. Biol. Lacustre, 3 ; 300-366, figs. 1-47.

Sadones, J.

'95. L'appareil digestif et respiratoire larvaire des Odonates. La
Cellule, 1 1 : 273-324, pis. 1-3.

580

Tillyard, R. J.

'06. Life history of Lcstcs Icda Selys. Proc. Linn. Soc. N. S.

Wales, 31 : 409-423, pis. 32, 33.
'11. On the genus Cordulephya. Proc. Linn. Soc. N. S. Wales,

36:388-422, pis. II, 12.
'12. On the genus Diphlebia, with descriptions of new species and

life histories. Proc. Linn. Soc. N. S. Wales, 36: 584-604, pis.

19-20.

\an der Weele, H. W.

'06. Morphologic und Entwicklung der Gonapophysen der Odo-
naten. Tijdschr. v. Ent., 49:99-198, pis. 6-8.

Walker, E. M.

'13. New nymphs of Canadian Odonata. Can. Ent., 45 : 161-170,

pis. I, 2.
'14. The known nymphs of the Canadian species of Lestes. Can.

Ent, 46: 189-200, pis. 13, 14.
'14a. New and little-known nymphs of Canadian Odonata. Can.

Ent., 46: 349-357. 370-377. pis. 23, 25.

Warren, A.

'15. A study of the food habits of the Hawaiian dragonflies or
pinau. College of Hawaii Publication.^;, Bull. 3, pis. 1-4.

Wesenburg-Lund, C.

'13. Odonaten-Studien. International Revue, 6: 155-228, 373-
422.

ADULTS

Ranks, N.

'92. A synopsis, catalogue, and bibliography of the neuropteroid
insects of temperate North America. Trans. Am. Ent. Soc,
19:327-373-
Brandt, A.

'69. Beitriige zur Entwickelungsgeschichte der Libelluliden und
Hemipteren, mit besonderen Beriicksichtigung der Liliclluliden.
Mem. Acad. Imp. des Sci. St. Petersb., ser. 7, 13 : 1-33. pis. 1-3.

Brauer, F.

'68. V^erzeichniss der bis jetzt bekannten Neuropteren im Sinne
Linne's. \'erhandl. d. k.-k. zool.-bot. Ge.sell. Witn, 18:359-
416, 711-742.

581

Calvert, P. P.

'93. Catalogue of the Odonata (dragonflies) of the vicinity of
Philadelphia, with an introduction to the study of this group of
insects. Trans. Am. Ent. Soc, 20: I52a-i52d; 153—272, pis.

2, 3.
'08. The composition and ecological relations of the odonate fauna

of Mexico and Central America. Proc. Acad. Nat. Sci. Phila.,

60: 460-491.
'08a. Odonata. Biol. Centr.-Amer., Neuroptera, pp. V— XXX, 17-

410, pis. 2-10.
'12. Progress in our knowledge of the Odonata from 1895— 1912.

Trans. Sec. Intern't'l Congr. of Ent., pp. 140—157.
'13. The species of Nehalennia (Odonata). Ent. News, 24: 310-

316.
'13a. The fossil odonate Phenacolestes, with a discussion of the

venation of the legion Podagrion Selys. Proc. Acad. Nat. Sci.

Phila., 65 : 225-272, pi. 14.

Calvert, P. P., and Hagen, H. A.
'02. (See Hagen and Calvert)

Hagen, H.

'61. Synopsis of the Neuroptera of North America, Smithsonian

Miscellaneous Collections, 1861 : 55-187.
'75. Synopsis of the Odonata of North America. Proc. Bost. Soc.
Nat. Hist, 18: 20-96.

Hagen, H. A., and Calvert, P. P.

'02. Illustrations of Odonata: Argia, with a list and bibliography
of the species. Bull. Mus. Comp. Zool., 39, No. 4: 103—120,
pis. I, 2.

Handlirsch, A.

'o6-'o8. Die Fossilen Insekten. 1430 pp., 51 pis. Leipzig.
'11. New Paleozoic insects from the vicinity of INIazon Creek,
Illinois. Am. Jour. Sci., ser. 4, 31 : 297—326.

Kellicott, D. S.

'9^. The Odonata of Ohio. Ohio State Acad. Sci., Special Pa-
pers, No. 2. 114 pp., figs. 1-39.

Kennedy, C. H.

'02. A list of the dragonflies of Winona Lake. Proc. Ind. Acad.

Sci., 1902: 159-164.
'02a. A new diagnostic character for the species of the genus
Argia. Proc. Ind. Acad. Sci., 1902: 164-169, pis. i, 2.

582

Kirby, W. F.

'90. Synonymic catalogue of Neuroptera Odonata, or dragonflies,
with an appendix of fossil species. 202 pp. London and Berlin.

Lucas, W. J.

'00. British dragonflies (Odonata). 356 pp., 27 pis. London.

Marshall, W. S.

'14. On the anatomy of the dragonfly, Libellula qiiadriniaculata
Linne. Trans. Wis. Acad. Sci., Arts, and Letters, 17, Pt. 2:
755-786, pis. 69, 70.

Morgan, Anna H.

'13. A contribution to the biologj' of the May-flies. Ann. Ent.
Soc. Amer., 6: 371-413. pis. 42-54-

Muttkowski, R. A.

'08. Review of the dragon-flies of Wisconsin. Bull. Wis. Nat.

Hist. Soc, n. s., 6: 57-123, pis. 4-6.
'10. Catalogue of the Odonata of North America. Bull. Pub.

Mus. City of Milwaukee, Vol. i. Art. i. 207 pp.

Needham, J. G.

'03. A genealogic study of dragon-fly wing venation. Proc. U. S.
Nat. Mus., 26: 703-764, pis. 31-54.

Packard, A. S.

'68. On the development of a dragon-fly (Diplax). Proc. Bost.
Soc. Nat. Hist., 11 : 365-372.

Poulton, K. B.

'06. Predaceous insects and their prey. Trans. Ent. Soc. London,
1906:323-409.

Ridgway, R.

'12. Color standards and color nomenclature. 43 pp., 53 pis.
Washington.

Ris, F.

'96. LTntersuchung iiber die Gestalt des Kaumagens bei den Libel-
len und ihren larvcn. Zool. Jahrb., Abt. Syst. Geogr. u. Biol.
Thiere, 9 : 596-624.

Scudder, S. H.

'90. The tertiarv insects of North America. Rep. U. S. Geol.
Surv. Terr.. XHL 663 pp., 28 pis.

Sellards, E. H.

'06. Tvpes of Permian insects. Am. Jour. Sci., ser. 4. 22: 249-
258.'

583

Selys-Longchamps, Edm. de

"62. Agrionines. 2""' Legion.-Lestes. Bull, de I'Acad. Roy. de^
Sci., des Lettres, et des Beaux-Arts de Belgique, ser. 2, 13:

291-338-
'65. Synopsis des Agrionines- [Argia]. Idem, 20: 375-417.
'76. Synopsis des Agrionines. Le grande genre Agrion. Idem.

41:247-322,496-539, 1233-1309; 42:490-531,952-991.

Selys-Longchamps, Edm. de, and Hagen. H. A.

'54. Monographic des Calopterygines. 291 pp., 14 pis.

Snodgrass, R. E.

'09. The thorax of insects and the articulation of the wings. Proc.
U. S. Nat. Mus., 36: 51 1-595, pis. 40-69.

Thompson, O. S.

'08. Appendages of the second abdominal segment of male dragon
flies (order Odonata). Bull. N. Y. State Mus., 124:249-263.
figs. 17-28.

Walsh, B. D.

'62. List of the Pseudoneuroptera of Illinois contained in the cab-
inet of the writer, with descriptions of over 40 new species, and
notes on their structural affinities. Proc. Acad. Nat. Sci. Phila.,
1862: 361-401.

Wijliamson, E. B.

'00. The dragonflies of Indiana. Dept. Geol. and Nat. Resources.

Ind., Rep. 24:233-333, pis. 1-7.
'00a. Notes on a few Wyoming dragonflies. Ent. News, 1 1 :

453-458. pl. 9_ _

'12. Hctacriiia titia and tricolor (dragonflies— Odonata). Ent.

News, 23: 98-101.
'12a. The dragonfly Argia iiiocsfa and a new species (Odonata).

Ent. News, 23 : 196-203.

Wilson, C. B.

'09. Dragonflies of the Mississippi valley collected during the pear!
_ mussel investigations on the Mississippi. River, July and August.
1907. Proc. v. S. Nat. Mus., 36:653-671.

5S4

INDEX TO GKNERA AND SPECIES

Aoshna, 463.

Agiion, 412, 417, 421, 442, 465, 466,
472.
aequabiie, 46.5, 467-469.

yakiina, 438, 467.
iiiaculatum,-438, 465, 467, 468, 469-

471.
vivgo, 439.
.Vmphiagrion, 465, 499, 500, 562. '

.saucium, 465, 562-564.
.^nax Junius, 412.
.Viionialagrion, 465, 500, 501, 575.

ha.statum, 465, 575-577.
Argia, 417, 421, 430, 444, 465, 499,
500, 501, 562.
apicalis, 445, 465, 502, 503-506, 507,

512, 514.
fumiponnis, 465, 502, 503, 506-507.
moesta putrida, 438, 465, 501, 502,

503, 507-510.
putrida, 440.

.sedula, 40.1, .502, .503, 510-511.
tibialis, 440, 465, 502, 503, 511-514.
violacea, 465, 502, 503, 515-517.

I 'aloptei yx, 413, 442.

virgo, 439.
Chroinagrion, 427, 465, 499, 500, 564.

coiulitum, 465, 565—567.
fora, 451, 457.

Knallagnia, 423. 465. .500. 501, 517.
anteiinatum, 438, 445, 465, 518, 520,

521-524.
aspersuMi, 465, 519, 520, 524-525.
calverti, 465, 476, 500, 518, .520, .521,

52.5-528, 536.
caninculatum, 442, 465, 476, 518,

519, 520, 527, 528-531, 532, 533,

534, 539, 540, 550.
civile, 445, 465, 476, 518, 519. 521,

527, 528, 531-534, .539. 540. 550.

Enallagma — continued.

cyathigenim, 465, 500, 518, 520, 521,

528, 534-536.
(livagans, 465, 476, 520, 521, 536-

538.
(loubledayi, 46.5, 476, 519, 521, 528,

538-540.
ebrium, 465, 520, 540-541.
exsulans, 442, 465, 518, 520, 521,

522, 524, 538, 542-544, 559.
geminatum, 442, 465, 517, 519, 520,

544^-547.
hageni, 439, 445, 465, 517, 520, 534,

.547-550.
piseinarium, 465.
poUutum, 465, 518, 519, 521, 550-

553.
pulchcllum, 439.
signatum, 438, 443, 465, 518, 519,

521, 544, .553-556.
traviatum, 465, 518, 519, 521, 556-

559.
Eiiphea, 457.

Gomphus, 430, 463.

Hetapiina, 417, 426, 434, 435, 444,
465, 466, 467, 471.
americana, 445, 465, 471-474, 475.
titia, 465, 471, 474-476.
tricolor. 476.

Ischnura, 435, 465, 500, 501, 567.
elegans, 439.
koUicotti, 465, 568-570.
posita. 465, 568, 570-572.
vcrticalis, 423, 438, 439, 440, 442.

443, 445, 465, 555, 568, 570, 571,

572-575.

Lestes, 418. 421. 422, 427, 430, 435,
438. 439, 440, 442, 444, 451. 465,
477, 485. 492.
congener, 465. 477. 478. 479-482.

585

Lestes — continued.

disjunctus, 465, 476, 478, 479, 481,

482-483, 485, 487.
eurinus, 465, 478, 479, 483-485.
foreipatus, 465, 476, 478, 479, 483,

485-487, 490, 492, 494, 496.
inaequalis, 465, 478, 479, 485, 487-

489.
reetangularis, 443, 465, 478, 479,

483, 487, 489-492, 494, 496.

uiic.Ttus, 465, 477, 478, 479, 492-

494, 496.
nngiiiculatiis, 465, 478, 479, 492,

494-496.
vis'ilax, 445, 465, 478, 479, 485, 489,

496-499.

Nehalonnia, 427, 465, 499, 500, 559.
Irene, 465, 559-561.

Sympetrum striolatiim, 439.

586

ABBREVIATIONS USED IN LETTERING PLATES

A, anal vein niasl,

A,-A,„ ahdominal segments 1-11 me,

aai, anal appemlages of aihilt-inferior mep,

aas, anal appendages of udult-siiperior md,

ag, aceessory genitalia of male me,

anc, antenodal cross-veins mfi,

ant, antennae miu,

arc, arculus ml,

awp, anterior wing-process mopl,

br, Ijridge mosl,

bsp, basilar space nip,

C, costa mpf,

cd, cardo mph,

ce, compound eyes nipp,
ci, corei ms,
cl, cardella msec,
ply, clypeus mscl,
cr, chitinous rod of the submentum

Cu„ Cu3,cubitus-branches of mse,

cw, claws msp,

ex, coxa mssii,

cxp, coxal process mst,

dc, dorsal carina mstg,

epcs, epicranial furrow mstm,

epm, epimeron mstv,

f, front mtcp,
fe, femur > mtfi,
fi, furcal invaginations mtn,
fl, furcella mtpf,
fs, femoral setae nitsc,

g, gills-caudal mtsl,

ga, galea mtsm,

gb, genital lobe mtst,
gd, gills-dorsal mtsu,
glc, galea-lacinia mx,
gn, genae nixp,
hm, hamules ml.
hp, h,\i)opharynx o,
ieps, infraepisternum oca,
insu, interpleural suture oco,
ints, intersternum ocr,
lb, labium oct,
Ibr, labrnm p,

le, lacinia pa,

Ik, lateral keel pel,

Ip, labial palpus pep,
lp„lp,, labial palpus-firsi and second scg pcxp,

ments pcpn.

Is, lateral setae of labial palpus peps,

M, media pg.

M„-M„ media, branches of the pi.

mapl, metapostseutellum pme.

metascutellum
median cleft of the labium
mesocoxal process
mandible
mentum

mesofurcal invaginations
microthorax, epimeron of the
median lobe of the labium
mesopostscutellum
mesoscutelhim
metaphragma

mesopref ureal invaginations
mesophragma

mesophragnial invaginations
mental setae

mesoscutum-caudal portion
niesoprescutum-cephalie portion
of mesoscutum

marginal setae of the median lobe

mesothoracic spiracle

mesopleural suture

niesosternum

mesostigmal plates (caudal)

mesosternellum

mesostigmal plates (ventral)

metacoxal process

metafurcal invaginations

metanotum

metaprefurca

nietascutum

nic'tathoracic spiracle

metasternellum

nietasternum

nu^taplcural suture

maxilla

maxillary palpus

nodus

ocelli

caudal valves or gonapophyses

cephalic valves or gonapophyses

occipital riilge

occiput

paraptera

paiamores

pronotum-caudal lobe

]Uonotum-cephalic lobe

procoxal process

proepimeron

proepistemum

postgena

palpiger

pronotum-median lobo

587

I'".

pronotiim

piie,

jiostnoilal eross-vcins

pps,

liio|ilciiral suture

pis,

piosfyles

prst,

presterniiin

ps,

penis

psct,

metaprescutuni

psl,

prosternollum

pst,

mcsoprcsteriiniM

pta,

pietarsiis

pwp,

posterior wiii<;-proecss

qd,

quadrangle

E.,

radius-first branch

Rs.

radial sector

Se,

subeosta

Sc„ Sc3

, subeosta, branches of

spps,

supraepisfernum

sni,

siiliMientuni

H'l',

spring-vein

St,

stigma

sti„

sternites (cauilal) of the eiglitli

abdominal segment

stp,

stipes

sv,

seminal vesicle

t,

tentorium

ta,

tarsus

ti,

tibia

tic,

tibial comb

Irii,

troeliantiu of mandible

tr,

trochanter

ts,

tibial setao

vx,

vertex

we.

wing-case

wp,

wiug process

Fig.

1.

Fig.

2.

Fig.

3.

Fig.

4.

Fig.

").

Fig.

(>.

Fig.

1 .

Fig.

8.

Fig.

9

Fig.

10

Fig.

11,

Fig.

I'i

Fig.

i:!.

Plate LVIII

NymphdJ Struct urcs

Enalldgma sp., ci'oss-si'etioii of the lioail tliniugli the

hyj)(jj)liai'ynx and maxillae.
Enallagma sp., cro.ss-section of the liead caiidad of the

section shown in Figui'c 1.
Enallagma sp., ero.ss-.scction through tlie lal)iuiii.
Enalldfjmd sp.. longitudinal section of the head.
Listfs forcipdtus, anal segments and bases of gills.
EiuillafjiiKi sp., eross-seetion of labium near hinge.
EnaUdfjinu rxsutdiis, ventral aspect of the head with

the labium folded iiack and the reinaiinng inouth-

I)arts in position.
Afirion mdculatum, la])iuni.
Ilctdfrimi dmcricdnd, labium.
Lrstcs forciptttus, labium.
Arfjid violdccd, labium.
Isdindni virlicdlis, labium.
l-hidlhif/ma ciininnildl iim. labium.

Plate LVIII

l'l,ATE LIX

Xjmplial Structures

Fif,'. 14. l^cstcs rccldnguhiris, wing-easc.

Fit?. 15. Hctdcrina (imcricdna, wing-easc.

Fig. 16. EiuiUuyma siynutum, wing-case.

Fig. 17. The same, young nymph, wing-case.

Fig. 18. hclinurii vrrticdlis, caudal end of the abdomen
with the two lateral gills removed.

Fig. 19. EnutUignui (xsulnm, tarsus.

Fig. 20. The same. leg.

Fig. 21. Isclinura lurtirulis. dorsum of meso- and
mctathorax.

Fig. 22. Agrirni niiiruIntunK maxilla.

Fig. 23. Hctnerina (imcricuna, dorsum of the prothorax.

Fig. 24. Isclinura verticalis, ventral aspect of thorax
and cephalic segments of abdomen.

Fig. 25. The same, lateral aspect of thoi-ax and ab-
domen.

Fig. 26. Emilhiymd sp., cross-section of gills.

Plate LIX

r Sr. Sc,

Plate LX
Nymplial and Adult Structures

Fis- 27. Isclinura verUcalis, adult, ventral aspect of pro-

thoi'ax.
Fig. 28. The same, adult, maxilla.
Fig. 29. Ilelacrina nmericdna. adult, viiilial as]iect of jiro-

thorax.
Fig. 30. Tschnura vertictilis. adult, caudal as])cct of head.
Fig. 31. Plcco])t('ra iiyHi]di. uiaxilla.

Fig. 32. IsclinHra vcrlicalis. adult, ccplialic asiieet of head.
Fig. 33. Heiaerina americdua, adult, vcuti'al view of the

second abdominal segment of the nude
Fig. 34. The same, adult, anal appendages, dorsal view.
Fig. 35. I.icJinura vertiadis, adult, leg.
Fig. 30. The same, adult, lateial view of ])i'othorax.
Fig. 37. The same, adult, labium.
Fig. 38. Ifcfficrina amcriraud, adult, latei'al view of auaJ

appendages.
Fig. 39. The same, adult, lateral view of prothoi'ax.

Plate LX

Plate LXI

Tlioniric Struct iir(s of AihiJts

Fi;^'. 40. Ihliurhm (inin-icinKi. \vu\vn] ;is]ici-t iil' the iin'so- aiul incta-

Ihtirax.
Fiii. 41. II( tdi riiKi tiliii, dorsal as])pr't of mcso- aiul nictathorax.
Fiix. 42. Isvlniiird vcrticalis. ventral as])('ot of iiicso- and niotathoi'ax.
Fig. 4o. The sanic, lateral as]K'ft of ine.so- and inetathofax.
Fiff. 44. The same, doi'sal aspeet of ineso- and nietathoi-ax.
Fiif. 4r). II(tii(ri)iii <nn(ririnui, latei'al asi)cet of nu^so- and nieta-

thorax.
Fig. 4(). The same, doisa! \ie\v of nieso- and metatei'Ka.
Fisr. 47. Isilntiini r(rli(iilis, dm sal view of meso- and nietaterya.

Plate LXI

Plate LXII

Caudal Gills of Nymphs*

Fig. 48. Lcstcs vigilax. Fig. 53. Enalhigma ersulans.

Fig. 49. Lestcs forcipnfus. Fig. 54. Enalhigma nnicnnatiim.

Fig. 50. Lestes congtncr. Fig. 55. Enallagma traviatum.

Fig. 51. Lestcs iingiiiculatus, Fig. 56. Enalhigma signatum.

normal gills. Fig. 57. Enallagma polluium.
Fig. 52. The same, dark gills.

*One of the lateral gills removed in most cases.

Plate LXII

Plate LXIII

Cduddl Gills of Xfimphs'*

Fig. 58. Argia moeatd putrkhi. Fit;. Ci. Ischnura verticnlk,

Fig. 59. AmpliiiiyriDH snuruDii. young nymph.

Fig. 60. Anomdldf/rioH hnstdfiim. Fig. 66. Iscknura positn.

Fig. 61. Xihdh nnid iiruc. Fig. 67. Argid (ipiciilis.

Fig. 62. Isclniiird rrrticdlis. Fig. 68. Argid iibidlis.

Fig. 63. Argid viohicea. Fig. 69. Endlhigmd signiifum,

Fig. 64. Isclnuird po.iita. variations in pig-

iiuMitation.

*Ono of tho l.-itoi:il tjills leinovoil in eases where the gills are attached to the
abdomen.

Plate LXIII

Plate LXIV
Caudal Gills of Xijmplis* and ^Yings of AduHs

Fig. 70. Enallayma carunculatum, Fig. 7G. Enallagma hagcni, gill.s.

gills. Fig. 77. Emdlagyna cxsulaus, dark
Fig. 71. Enallagma ciiatliigcrum, and light gills.

gills. Fig. 77a. The sanic. aljiiormal gills.

Fig. 72. Enallagma gi minalam, Fig. 78. Ilctacrina amcricana,

gills. male, wings.

Fig. 73. Agrion avquahdc, wings. Fig. 79. The same, nymphal skin.

Fig. 74. Ilctacrina amcricana. Fig. SO. Eiudlagma ( ?) ctdvcrti,

wings. lateral gill.

Fig. 75. Enallagma civile, gills.

*One of the lateral gills lemoveil in casos where the gills are attached to the

abdomen.

Plate hXlV

Plate LXV

Wings of Adulfn

Fig. 81. Iscliiuirti vcrfieiills. Fig. SO. Isclnnini positu.

Fig. 82. Anonuilagrion Ixistdlum, Fig. 87. Endlhigmn liagcni.

female. Fig. 88. Xdidloinii! irene.

Fig. 83. The same. male. Fig. 89. Amphiagrion sduchiin.

Fig. 84. Cliromagrion conditioii. Fig. 90. Argin <ipirnlis.
Fig. 85. Lisic.s rtdangularis.

Plate LXV

Ri*Sc:

Ti^vTE LXVI

Abdominal Struchti'es of Adults

Fig. 91. Eiudlagnid caruncidnhnii, fcmalu, dorsal view of abdoiiioii.

Pig. !)2. Encdhiyma civilr, fciualo, dorsal view of ahdoincii.

Fig. 93. En(dla(j)Hii cyaihiijinon, female, dorsal view of abdomen.

Fig. 94. EnaUdgiiiii Iraviatum, female, dorsal view of abdomen.

Fig. 95. EiudUtgnut (i.spersum, female, dorsal view of abdomen.

Fig. 96. EtudliiyDKi (jeviinutitm, female, dorsal view of abdomen.

Fig. 97. Enidhigma raruncuhdum, male. ])enis.

Fig. 98. En(dhtgma njdihigtrum, male, jienis.

Fig. 99. Eiudhigma cdrtnicidiition, female, caudal abdominal segments.

Fig. 100. AnoDidldgrioH liiisidlum. female, eaudal al>domiiial segments.

Fig. 101. En(dldgma liagoti, male, penis.

Fig. 102. Chromagrion conditum, male, anal ap])endages.

Fig. 103. Enalldgma civile, male, anal appendages.

Fig. 104. Ischniird vcrticdlis, female, candal abdominal segments.

Fig. 10."). Eiudhigma civUe, male, penis.

Fig. lot). Chromagrion condiltim, male anal a|ip(iidages.

Fig. 107. En(dJdgmd rhriinn, male, ])enis.

Fig. 10<S. Eiidlldg>iid cdlvi rli, male, penis.

Plate LXVI

Plate LXVII
Abdominal Stnicturcx of Adults

Fig. 109. Ayrion mdculnfum, fcinalf. caudal end of abdomen.

Fig. 110. Ayrion (icquabile, female, caudal end of abdomen.

Fig. 111. Ilciuerina titia, female, caudal end of abdomen.

Fig. 112. Hetaerina (imcricann, female, caudal end of abdomen.

Fig. 113. Lestes un<'(itus, female, caudal end of abdomen.

Fig. 114. Lcstes forcipaius, female, caudal end of abdomen.

Fig. llf). Lcstrs rrctdngithiris. female, caudal end of alxlomcn.

Fig. 116. Argia mocsta putrida, female, caudal end of abdomen.

Fig. 117. Ayri-on aequabile, male, anal appendages.

Fig. 118. The same, male, sternum of the ninth segment.

Fig. 119. Hcfaerina iitia, male, anal appendages.

Fig. 120. Lesics disjuncfu.t, male, second abdominal segment,
from side.

Fig. 121. Hetiitrind unicricdnii. male, sternum of the niiitli seg-
ment.

Fig. 122. Lestes forcipatus, male, second abdominal segment,
lateral view.

Pl,ATE LXVII

111

113

115

117

119

120

Pl.\te LXVIII

Anal A]ipi ndiKjcs of Adulfs

Fig. 123. Lcsles congou r. Fig. 132. Lestes iunrqualis.

Fig. 124. Lestes congener. Fig. 133. Lestes (tisjiinctus.

Fig. 125. Lestes vnguiculatus. Fig. 134. Agrion acqudbile.

Fig. 126. Lestes unguiculatus. Fig. 135. Lestes unciitus.

Fig. 127. Lestes rectangiddris. Fig. 130. Lestes nncntits.

Fig. 128. Lestes rectfingularis. Fig. 137. Lestes forcipnfus.

Fig. 129. Lestes vigiliix. Fig. 138. Lestes forcipntus.

Fig. 130. Lestes vigilii.r. Fig. 139. Agrion mdciildttim.

Fig. 131. Lestes indcqudlis. Fig. 139a. Agrion mdcuhitiivi.

Plate LXVIII

134

139

Fi

FiK,

Fit?

FiK

Fij--

Fi-

FiK

Fi-

Fif--

Fi-

Fi-

Fit?

Fit?

Fi-

Fit?

Fit?

Fit?

Fit?

Fis?

Plate LXIX
Thorririr and Abdominal Slrucfurcs of Adults

140. Aryiu libi(dis, female, mcsostigmal plates.

141. Argia sedula, female, mesostiginal i)lates.

142. Argia violacca, female, me.sostit?iiial ])latos.

143. Argia fumipcyims, male, anal a])peiidat?es.

144. The same, male, anal a]ii)('n(lat?es.
14."). Argia violacca, male, anal ap])endages.

146. The same, male, anal ai)7)endat?es.

147. Argia apicalis, male, ninth .stcnmm.

145. Argia fumipennis, female, mesostit?mal plates.

149. Argia sedula, male, anal appendages.

150. Thei same, male, anal appendaties.
1.51. Argia apicalis, male, anal apjiendages.
152. The same, male, anal appendages.
15;i. The same, female, mesosti-mal plates.

154. Argia viocsla puirida. female, mesosti-mal plates.

155. Argia iihi<dis, male, anal ajipendages.

156. The same, male, anal ai)penda-es.

157. Argia moesta pufrida, male, anal a])])endages.
15S. The same, male, an;'.l appendages.

Plate LXIX

152 158

Plate LXX

ThoriK l< (1)1(1 Abdominal Stntcturcs of Adidls

Fig. 159. XilHd()niiii ir()i(, iiiaio. anal appendages.

Fig. 160. The same, male, anal aiipendagcs.

Fig. 161. EH(dI(i(jni<i luigcni, male, anal appendages.

Fig. 162. The same, male, anal appendages.

Fig. 163. Isclinurii positit, female, mesostigmal plates.

Fig. 16-4. Anom(d(i(jrion lutxtutum, female, mesostigmal plates.

Fig. 165. EtudhKjma (isptrsum, male, ninth sternum.

Fig. 166. A)io>n(iht(/ri(jn luistdtum. male, anal ai)i)endages.

Fig. 167. The .same, male, anal appendages.

Fig. 168. Ischnura. v(rtic(dis male, anal ai)pendagcs.

Fig. 169. EiKdhiymn doubJcddni. ma\e. right suiieiinr apjien-
dage seen f i-om the left and above.

Fig. 170. Chroma (jrion conditum, female, mesostigmal jilates
and dorsum of prothorax.

Fig. 171. Isclinura. posita. male, ninth sterniun.

Fig. 172. Anomid(i(/ri(nt ItaMtatum. male, ninth sternum.

Fig. 173. Isclniiira jxjsita, nude, anal aj^pendages.

Fig. 174. Ampltiaiirion sauciKm. male, anal a])]iendages.

Fig. 175. En(dla(i)iia ddultUdatii, male, anal aiii)endages.

Fig. 176. EnaUatpna caruncuJafum, male, right superior ap-
pendage seen from the left and above.

Fig. 177. Isclinurit posita, male, anal appendages.

Fig. 178. Amphiagrion saucium. male, anal appendages.

Fig. 179. Erudhujma civile, male, right superior appendage
seen from the left and aliove.

Fig. 180. Tsclinnra vcrtic(dis, female, mesostigmal |)lates.

Fig. 181. Ampliidfirion saucium, female, me.sostignial jdates..

Fig. 182. X(hid( nnia ircne, female, mesostigmal i)lates.

Fig. 183. The .same, male, ninth abdominal sternum.

Plate LXX

168

166

173

177

160

167 J-

174

178

176 179

#*r:::TrZ7::r:rr#^

181

Plate LXXI

Anol Appendages of Adults

Fig.

184.

7,sc7) ?! ura hellicotti.

Fig.

198.

EnaUagma

civile.

Fig.

185.

EnaUagma signntum.

Fig.

199.

EnaUagma

iraviatum.

Fig.

186.

EnnUagmn pollutum.

Fig.

200.

EnaUagma

calverti.

Fig.

187.

Eudlhigmd cdruncula-

Fig.

201.

EnaUagma

cgathigerum

fum.

Fig.

202.

EnaUagma

anfcnnatum.

Fig.

188.

Enalhigmd dspcrsum.

Fig.

203.

EnaUagma

crsulans.

Fig.

189.

EudUdgniii ehriinn.

Fig.

204.

Enallagyna

gcminatum.

Fig.

190.

E nallagm a divdgans.

Fig.

205.

EnaUagma

carunada-

Fig.

191.

Tschniira kellicotti.

turn.

Fig.

192.

Eudlldgma signatum.

Fig.

206.

EnaUagma

trnviaium.

Fig.

193.

Endllagma pollutum.

Fig.

207.

EnaUagma

calverti.

Fig.

194.

Ennlhigmd cdruncula-

Fig.

208.

EnaUagma

cgatliigerum

tum.

Fig.

209.

Enidlagma

antennaium.

Fig.

19.").

Enitlhigmd dspersum.

Fig.

210.

Enallagyna

crsulans.

Fig.

19fi.

Eudlldgwd. rhrium.

Fig.

211.

EnaUagma

gcminatmn.

Fig.

197.

Endllagma divagans.

Plate LXXI

184

191

198

205

206

207

208

202 -i

188

196

209

189 J

203 ■•

196

210

190

197

204

211

Fis
FiK
Fis
Fi-
Fisj
Fig
FiK
Fifi-
Fig
Fis
Fig
Fiff
FiK
Fiir
Fis
FiK

212.
2l:J.
214.
21').
21().
217.
2 IS.
219.
220.
221.
222.
223.
224.
225.

226.
007

Pl.\te LXXII

Thortiric Struclurcs of Adults

Emilhuimit civiU. incscistisiiial i)latcs.

EnnJJdiiinii. ( i/dtliifjirum, nicso.stigmal plates.

EniiUdniiiii siyudiuyn, niescstismal plates.

E\i(iU(i(i)H<i ctiruncuhiium, niesostigmal plates.

EniiUdipiiii (jcminntum, nie.sostiKiiial plates.
Iscliniird vcrticdlis, nyini)li. (See Plate LXXITI.)

EiidUiuimd irdvldtum, iiies<)sti<jnial jilates.

E iidlldi/)iid diih nndlion. lucsostiu'iiial jtlates.

EiKilldjinid ( .rs}ild)ix, niesiistifjliial i)lates.

EndUiujmd ]>d(j< ni, iiiesostiKiiial plates.
Agrian 7ndculdfu»i, nymph. (See Plate LXXllI.)

EndUdgma cdlvcrii, niesostigmal plates.

Endlhigmd divdgans, nicso.stifriiial plates.

Enalldgmd jxtll iit iiDi, niesostijrmal ])lates.

Endlhigmd (hm}iJ( dagl, inesostiuinal plates.

EndUdgmd ( /u'/in», niesdstitfinal plates.

228. Lestcs forcipdiiis. nynipli. (See Plate LXXIII.)

Plate LXXII

213

220

221

<^ 214 C

■^**^4aiC:

/'

215

223

224

218

219

® 225 ^

^^rTT"^

226

^

227

Plate LXXIII

Nymphs

Fig. 217. Isclinura vciiicalis.
Fig. 222. Agrion mucuhitum.
Fig. 228. Lestes forcipatus.

Plate LXXIII

/
y^l

V' }<^'^-*- -''Siinsl^

217

/ i I

228

^* •

^i^ii/ o> -Vi m

y

Vx

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