ISCHNURA 355 
those of 8 united by a narrow, transverse, basal black band, and of 9 by a trans- 
verse apical band in some specimens, but not united on either 8 or 9 in others. 
A narrow, transverse, interrupted, basal yellow ring on 3-7. Forked process on 
10 about half as high as 10 itself. Superior appendages black, very short, one- 
fourth as long as 10, tubercular, with a slender, inner inferior prolongation 
reaching to the base of the inferior appendages. Inferior appendages two-thirds 
as long as 10, similar to those of denticollis, but with the apical processes a little 
more robust and curved upwards as well as inwards at the extreme tip. 
The females of this species exhibit the usual homochromatic and heterochro- 
matic phases so common to the species of this genus. The prothorax of the 
female has the hind margin distinctly bilobed. The ventral spine on the apical 
margin of abdominal segment 8 is either vestigial or entirely wanting. 
357. Ischnura verticalis Say 
Say ’39, p. 37: Mtk. Cat. p. 70: Lyon ’15, p. 59: Calv. 715, p. 62: Garm. ’17, 
p. 572 and ’27, p. 44. 
Syn: discolor Burm. 
Length 20-30 mm. Expanse 32-38 mm. Me., Ont. and N. Dak. to Ga. and Texas 
Within its range, this is the most common Zygopteran in North America, 
occurring in large numbers everywhere that there is enough water for the nymphs 
to live. The adults appear early in May and continue to emerge until September 
or later. Male. Labrum pale green with a black basal stripe. Postocular spots 
bluish-green, round, and isolated. A narrow pale postocellar stripe present. 
Anteclypeus pale; postclypeus black. Vertical portion of the frons pale; hori- 
zontal portion black. Antennae, vertex and occiput black. Mouth parts, genae 
and postgenae pale bluish-green. Dorsum of middle prothoracic lobe and pos- 
terior lobe black, remainder of the prothorax pale. Black middorsal and humeral 
stripes wide. The pale antehumeral stripe entire and narrow. A black spot on 
the base of the second lateral suture and a black spot and indefinite brown line 
on the third lateral suture. Dorsum of abdominal segments 1—7 and 10 black 
with narrow, yellow interrupted basal rings on segments 3-7. Segments 8-9 
blue, with large rectangular basal black spots on either side, those on 8 con- 
nected across the dorsum by a black basal line. 
The females exhibit the homochromatic and heterochromatic phases, and 
as this is the most common damselfly showing this phenomenon, much work 
has been done on it. For a fuller account of this interesting matter see the 
introduction to this genus and the 1915 papers of Dr. Calvert and Miss Lyon 
cited above. 
358. Ischnura cervula Selys 
Selys ’76, p. 262: Mtk. Cat. p. 68: Kndy. 717, p. 295: Ndm. ’23, p. 131. 
Length 29 mm. Expanse 34 mm. B. C. and Calif., Utah, Ariz., N. Mex. 
A far western all-summer species. Male. Color of the head mainly black 
with reduced pale markings as follows: Mouth parts, labrum except for a basal 
line, anteclypeus, vertical surface of the frons, and two very small postocular 
spots. The prothorax black except for a transverse pale stripe on the anterior 
lobe, and an interrupted bluish-green vertical stripe on each side which runs 
down into the coxa. Thorax with the sides blue. A black spot and line on the 
