. Bulletin. Natural history; Natural history. March 1938 ROSS: NEARCTIC CADDIS FLIES 125 pressed on meson. Oedagus with basal tube less than two-thirds length of apical portion; spiral process short, cir- cling only halfway around the tube; the tube divided immediately beyond this point, the two tubes thus tormetl progressing side by side to their apex where they may separate; one of them becomes smaller toward the apex and finally terminates as a narrow filament; the other narrows, then widens again and finally narrows to a small tip. Beside the oedagus a small rodlike structure, .v, has been
. Bulletin. Natural history; Natural history. March 1938 ROSS: NEARCTIC CADDIS FLIES 125 pressed on meson. Oedagus with basal tube less than two-thirds length of apical portion; spiral process short, cir- cling only halfway around the tube; the tube divided immediately beyond this point, the two tubes thus tormetl progressing side by side to their apex where they may separate; one of them becomes smaller toward the apex and finally terminates as a narrow filament; the other narrows, then widens again and finally narrows to a small tip. Beside the oedagus a small rodlike structure, .v, has been observed, which is apparently associated with the oedagus but which has not been oriented with certainty. Holotype, male.—Herod, Illinois: Mav 29, 1935, Ross &' Mohr. Paratypes.—Illinois.—Herod: April 19, 1937, along Gibbons Creek, Ross & Mohr, Id'. Oklahoma.—Turner Falls State Park; June 2, , along Honey Creek, H. H. Ross, 20 cf. Hydroptila tortosa new species This species is a member of the hamata complex but differs from the other species of that group in the peculiar oedagus, fig. 39. Male.—Length mm. Color anti. Style of Seventh <3 Stermite Fig. 39.—Hydroptila lorlaa general structure same as for anioena except for the legs, which have the femora and tibiae dark brown. Seventh sternite has a long, slender process clothed at base with long setae, the apex enlarged but laterally compressed and having the ventral margin serrate. Genitalia as in fig. 39. Basal arm of ninth segment short, no longer than segment itself. Tenth tergite pointed, as seen from lateral view; divided into two ovate lobes, as seen from the dor- sal view, without setae. Claspers saber- like, curvecH meso-ventraii and almost touching on the meson; thickness uni- form for most ol length, apex pointed, ventral half with minute setae. Oedagus very long, the basal portion about equal in length to the apical portion which has a heavy, sinuate central stem, the apex of which is
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