1955] 
Gibbs — Females of Enallagma 
17 
— Twisted lateral portion of lamina not bent posterior- 
ly; lamina definitely demarcated only in lateral half; 
prothoracic pits present; segment one with a black 
basal spot, lateral apical spots; segment 8 with black 
slightly narrowed anteriorly; black of segments 9 
and 10 not extending much beyond a mid-lateral 
point laterale 
7(5) Mesal edge of lamina at about 30 degree angle to 
mid-dorsal carina ; postero-mesal corner much more 
thickened than antero-mesal, posterior edge broadly 
curved in mesal half, mesal half much broader than 
lateral half ; pit in frame rather wide ; prothoracic 
pits present; black of segment 8 constricted in basal 
half, no lateral stripe present on 2 or 8 recurvation 
— Mesal edge of lamina nearly parallel to mid-dorsai 
carina ; antero-mesal corner more thickened than pos- 
tero-mesal, posterior edge nearly straight, mesal half 
not greatly broader than lateral half ; pit in frame 
rather small; prothoracic pits absent (sometimes a 
deceptive set of shallow areas present) ; a lateral 
black stripe present on segment 2 ; black of segment 
8 narrow dorsally, a black lateral stripe present, 
the two black portions enclosing a blue spot on each 
side geminatum 
8(3) Lamina nearly flat except tilted antero-lateral margin; 
prothoracic pits present davisi 
— Lamina not flat; anterior open concavity present; 
prothoracic pits absent 9 
9(8) Mesal edge of lamina at about a 30 degree angle to 
mid-dorsal carina; postero-mesal margin sharply de- 
limited from the thorax by a groove cyathigerum 
— Mesal edge of lamina nearly parallel to mid-dorsal 
carina; postero-mesal margin not clearly demarcated 
f rom thorax boreale 
