252 NEW YORK STATE MUSEUM 
been studied and collected sufficiently for the determination of 
this matter. It would be utterly impossible at present to give 
a key that would distinguish females, and a key for the males 
based on coloration would have to be offered tentatively, since 
the range of variability in color pattern has not been determined. 
Instead of attempting a key, I have thought best to present 
herewith drawings of the appendages of the male of all species 
known from the State, these being the surest criteria for the 
recognition of the species. _The males can then be determined 
by comparison with the figures, and the females can be kept 
with the males with which they are found associated in nature. 
As is to be expected in such a genus, the nymphs are very 
much alike. A brief general description here will therefore save 
much repetition in treating of the species. 
Nymph. The nymph of Enallagma is slender, nearly smooth, 
with the head a third wider than succeeding parts of the body 
(the excess of width being wholly due. 
to the lateral prominence of the eyes), 
and with abdomen very slightly taper- 
ing posteriorly. The head is one half 
wider than: long, with frons moder- 
ately prominent, broadly rounded hind 
angles, and a wide posterior excava- 
tion between them. Antennae long, 
slender, seven jointed, the segments 
increasing in length to the third, and 
decreasing thereafter to the tip. Legs 
slender, nearly smooth, often banded © 
with brown. Wing cases reach pos- 
teriorly to the middle of the fourth 
abdominal segment. Abdomen cylin- 
dric, its segments decreasing a very 
little both in length and in diameter 
toward the apex. Gills lanceolate, 
pointed, with variable color pattern. 
Labium slender, with prominent 
median lobe, lateral lobes upeurved at 
BE iigciecn on cena atlie ct their external margins; mental setae 
ott tacit 4» lateral view ofmedian two to four each side. Lateral setae 
four to five each side. Lateral lobe 
with a moderate movable hook and an arcuate end hook and 
several small teeth on the distal end above the latter, of variable 
proportions. 
