178 DRAGONFLIES OF NORTH AMERICA 
was beautiful to witness. They seem to be a bit social; for the air would 
be full of them for a few miles, and then there would be stretches of the 
river where none were to be seen. 
A dilatation of the river known as Chipola Lake was probably the 
source of these swarms. On the trunks of the cypress trees standing in 
the lake the cast skins of nymphs of this species were very common 
hanging to the bark or to the moss often as high as one could reach from 
a boat. 
30. TETRAGONEURIA Hagen 
Dog-tails: Wags 
These are dragonflies of rather large size. The coloration is brownish, 
non-metallic with scanty and rather obscure yellowish markings. The 
thorax is clothed with hoary hairs. The wings are hyaline except for 
basal subcostal streak and a basal post cubital spot on the hind ones, 
very variable in extent and in separatiness, according to species and 



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etragoneuria cynosura. 
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variety. These markings are almost wanting in 7’. stella and they over- 
spread half the wing in 7’. cynosura. The venation is open, being re- 
duced to a minimum and perfected in adjustment, giving excellent 
powers of flight. The subgenital plate of the female is very long, often 
longer than the ninth segment, and cleft to the base in two divergent 
linear lobes. 
These dragonflies are very agile. Their flight is rarely straight ahead 
for any great, continued distance. It is rather a continual succession of 
dartings and dodgings from side to side. Though they are not shy and 
will allow one to approach rather near, they are not easy to capture. 
Hence they are not so common in collections as their great abundance 
in nature would lead one to expect. They are pugnacious and often 
pursue larger species about as a kingbird harasses a crow. 
