87 
questionable nymphs of plagiatus. Walsh apparently included 
both species in his fluvialis, described from specimens collected 
about Rock Island, but his statements of the habits of fuvialis, 
which are quite unlike those we have recorded for p/lagiatus, 
very likely apply to nofatus, and may account for its apparent 
rarity. He says that while fraternus and vastus haunt the land 
and are easy to capture, fuvialis “makes long excursions to and 
fro on the surface of the river, scarcely ever approaching the 
land except for a second.” 
Williamson (’01b) lists the species from Illinois, Michigan, 
Ohio, Tennessee, and Quebec, Canada; June 1 and 21 in Ohio 
and Michigan, and September 30 in Tennessee. 
21. Gomphus spiniceps Walsh. 
Macrogomphus? spiniceps Walsh, '62, p. 389 (female). 
Gomphus spiniceps, Kellicott, '95, p. 209 (male). 
Gomphus segregans, Needham, 97, p. 185 (male). 
This seems to prefer somewhat rapid currents. Excepting 
a single example from the Illinois River, the nymphs appear in 
the Laboratory and Biological Station collections only from 
Quiver Creek and Quiver Lake near the mouth of the creek.* 
This creek is a peculiar and beautiful stream, shallow and 
sandy, fed by springs of soft water flowing out of the sand 
beds, and hence quite uniform and constant in its flow. At 
the mouth of this stream spiniceps is associated with externus 
and plagiatus. The nymph agrees with that of plagiatus in 
having no dorsal elevation or hooks except a single rudimentary 
posterior tooth on the penultimate segment, but differs from it 
conspicuously in the form of that segment, which is long and 
narrow, the lateral margin fully twice the basal width. In this 
character it resembles Gomphus pallidus, but has not the elevated 
dorsal ridge nor the long tenth segment of that species. As 
in the case of plagiatus and externus, nymphs placed in breed- 
*Numerous exuvie and emerging individuals have since been taken on the 
rocky walls of the shallow gorge of the Illinois River at Ottawa, July 21 and 
August 19, the larger number of imagos being secured on the latter date, 
