78 DRAGONFLIES OF NORTH AMERICA 
displaced by Ophiogomphus occidentis. I have not found it on streams which 
carry much snow water. It is found on the same streams that are occupied by 
Octogomphus, but the latter stays on the torrential headwaters while bison 
occupies the lowland sluggish portion of the stream. 

mainensis 
“Tt is usually foundon gravel bars bordering ariffle and seldom more than five 
or six are found at one place. The females oviposit where the water is swiftest.’ 
22. Ophiogomphus mainensis Packard 
Pkrd. ’63, p. 255: Mtk. Cat. p. 84: Ndm.’97, p. 182: Harv. ’01, p. 209: Wood- 
ruff ’14, p. 61: Howe 18, p. 29: ’23, p. 128: Garm. ’27, p. 137. 
Syn: johannus Ndm. 
Length 42 mm. Expanse 55 mm. Me., N. Y., Pa, 
A small yellowish green species, striped with brown. Head and thorax clothed 
with brownish hairs. Face and occiput yellow. The occipital border is cleft and 
produced into a pair of long sharp horns that are directed forward. Thoracic 
stripes of the first pair narrowly linear, slightly separated by the pale carina, 
complete from crest to collar, much narrower than the pale area alongside. 
Stripe 2 free at upper end, then fused a little with 3, then separated by a pale line 
below, hardly as wide as 3. Stripe 4 almost obsolete, reduced to two dashes 
at the ends. Stripe 5 continuous, narrowly linear. Legs brownish, pale on under 
side of femora. Wings hyaline costa scarcely yellow, stigma pale. Middorsal 
line of pale markings on abdomen reduced to abbreviated triangles on the middle 
segments, absent on 7 and 8 reappearing on 9; 10 pale. The lateral margins of 
the slightly dilated 7 to 9th segments yellow, with a brown border about the pos- 
tero lateral margins of the segments. Appendages brown. 
9. ERPETOGOMPHUS Selys 
These are clear-winged dragonflies of elongate form and rather 
striking coloration. Patterns in black and yellow with much repetition 
on the segments of the long body have suggested a lot of snaky names 
