55 
II. Progompuus Selys. 
Progomphus obscurus Ramb. 
The nymph of this species has divergent wing-pads, like 
Diastatomma, but differs from all our other gomphids in the 
proximity of the middle legs. It represents an extreme of 
specialization for life as a burrower in the bed of running 
streams. It has not been found in the Illinois nor in its adja- 
cent lakes, but seems to be common in the sand of the smaller 
rivers, such as the Spoon River and upper Sangamon. The 
State Laboratory has a large number of examples from the 
latter river, taken in September and October. One specimen 
was found at the lower edge of a sand-bar in Spoon River, near 
Havana, in July. The published dates for the nymph are April 
(Fla.), May, and June. The adults are rare in collections, 
although the species seems widely distributed. Perhaps the 
pecuhar habits of the nymph may be correlated with a rela- 
tively long period of nymphal life and short period of life as an 
imago. The adult has been taken in Indiana as early as June 
26, and in Illinois June 29 and July 13. It is recorded from 
Massachusetts, Georgia, Ohio, Indiana, Florida, Texas, Cali- 
fornia, Oregon, and Mexico. 
The nymph was described and by supposition connected 
with this species by Hagen (’85, p. 247), and the supposition was 
verified by Mr. Needham (97, p. 154). 
The nymph measures 31 mm.; abdomen, 20 mm.; hind femur, 
4 mm.; width of abdomen, 6 mm., of head 5 mm. 
Body depressed anteriorly and tapering posteriorly ; lateral 
margins with long hairs. 
Head depressed, sloping anteriorly, cordate, broadly notched 
behind ; hind angles rounded, Antenne inserted into cylin- 
droid elevations on the front, depressed and incurved so as to 
almost surround the pilot-shaped labrum ; two basal joints very 
short; third, twice as long as the two basal combined, slightly 
flattened and upcurved at the tip; fourth joint small, one third 
to one fifth as long as the third, slender and strongly recurved. 
