344 DRAGONFLIES OF NORTH AMERICA 
by their color and their color pattern. To one of these phases has been 
given the name Homeeochromatic or black female; to the other, Hetero- 
chromatic or orange female. They may be characterized as follows: 
Homeochromatic female (mature): Color blue or green, and black. 
Pale postocular spots small and not confluent with the pale color of the 
rear of the head. The predominant color of the thorax is pale bluish. 
The black humeral stripe is wider than the pale antehumeral. The dor- 
sum of abdominal segment one is dark metallic blue or green, only the 
articular membrane between 1-2 is pale. The dorsum of segment 2 is 
dark metallic green or blue for its entire length, narrowed at its hind 
margin. Dorsum of segment 3 metallic green or blue contracted at the 
anterior end to a middorsal line, and at the hind end to a smaller 
degree. The sides of segments 1-3 are pale bluish. 
Heterochromatic female: Color yellow or orange, and black. Pale 
postocular spots more or less confluent with the pale color of the rear of 
the head. The predominant color of the thorax is yellow or pale orange. 
The black humeral stripe narrower than the pale antehumeral stripe. 
Dorsum of abdominal segment 1 orange with pale black dots; 2, yellow 
or orange with black markings varying from a narrow crescent at two- 
thirds the segments length to spot on the first—and one on the third— 
third, connected by a fine dorsal line; 3, yellow or orange the hindmost 
fourth dark metallic green prolonged forward as a tapering black line 
almost to, or to, the fore end of the segment; sides of 1-3 yellow or 
orange. . 
Both of these forms have, when newly emerged, the 8th and 9th . 
abdominal segments pale blue, each segment with a short basal black 
stripe on each side of the segments, connected across the dorsum by a 
black basal line, wider on 8 than on 9. There is no constant difference 
in the size of these two females. 
It will be observed from the above descriptions that the Homeeochro- 
matic female has in general the same color and color pattern as the male, 
while the Heterochromatic female has the customary blue-green color 
of the male replaced by orange or yellow, and the color pattern radi- 
cally altered. 
The nymphs of only six of our fifteen described species of Ischnura 
are known. The nymph of this genus resembles that of Enallagma very 
closely but the gills have long tapering points, while those of Enallagma 
are more blunt, sometimes being quite rounded. The number of de- 
scribed nymphs are too few to make the writing of a key practical. The 
following table of characters has been drawn up instead: 
