. Bulletin. Natural history; Natural history. 212 Illinois Natural History Survey Bulletin Vol. 23. Art. 1 between convex Ri and convex Cui, fig. 734 2 2. M apparently not branched, fig. 734 Oecetis, p. 236 M obviously branched, fig. 735 3 3. Epicranial stem distinct, lateral su- tures absent or indistinct, fig. 736; katepisternum constricted at apex, fig. 739 4 Epicranial stem absent or indistinct, lateral sutures well marked, fig. 738;. Fig. 736.—Mystacides sepulchralis, head. Fig. 737.—Selodes vernalis, head. Fig. 738.—Athripsodes tarsi-punctatus, head. Fig. 739.—Mystacides sepulchralis, me
. Bulletin. Natural history; Natural history. 212 Illinois Natural History Survey Bulletin Vol. 23. Art. 1 between convex Ri and convex Cui, fig. 734 2 2. M apparently not branched, fig. 734 Oecetis, p. 236 M obviously branched, fig. 735 3 3. Epicranial stem distinct, lateral su- tures absent or indistinct, fig. 736; katepisternum constricted at apex, fig. 739 4 Epicranial stem absent or indistinct, lateral sutures well marked, fig. 738;. Fig. 736.—Mystacides sepulchralis, head. Fig. 737.—Selodes vernalis, head. Fig. 738.—Athripsodes tarsi-punctatus, head. Fig. 739.—Mystacides sepulchralis, meso- pleuron. Fig. 740.—Leptocella albida. Fig. 741.—Athripsodes transversus. em, mesoepimeron; ep, epicranial stem; k, katepisternum; Is, lateral suture. katepisternum truncate at apex, fig. 740 5 4. Dorsal triangle of head small, epicra- nial stem long, fig. 737; color whitish, straw yellow or light brown Setodes, p. 256 Dorsal triangle of head large, epicra- nial stem short, fig. 736; color very dark brown or bluish black, includ- ing wings Mystacides, p. 253 5. Meso-epimeron membranous nearly to ventral margin, fig. 740; hind wings with most of Rs and its branches atrophied; ground color white Leptocella, p. 213 Meso-epimeron with a wide sclero- tized bridge between membranous area and ventral margin, fig. 741; • hind wings with Rs and its branches present; ground color not white. . 6 6. Front tibiae with 2 apical spurs Athripsodes, p. 221 Front tibiae without apical spurs. . Leptocerus, p. 212 Leptocerus Leach Leptocerus Leach (1815, p. 136). Genotype, monobasic: Phryganea interrupta Fabricius. Ymymia Milne (1934, p. 16). Genotype, monobasic: Setodes americana Banks. The curious translucent case, the hooked middle leg and anal tufts of the larv,ae, and the genitalia of the adults readily distinguish the only North American species of this genus. The type of case, structure of larva and adult venation leave no doubt but that americanus is congeneric with the ge
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