. Bulletin. Natural history; Natural history. 62 Illinois Natlral History Survey Bulletin Vol. 26, Art. 1 filamentous gills absent on first ab- dominal segment - Platclike gills present on abdominal seg- ments 4-7, figs. 162-164; filamentous gills present on first segment 4 Frontal shelf of head without such a notch 8 I'Vonta! shelf with a pair of small, triangu- lar, lateral projections, fig. 156 1. lata. 157 ?S Fig. 151.—Ephemerella hicolor, head of mature male nymph, anterior aspect. Fig. 152.—Epliemtrrlla hicolor, head of mature female nymph, anterior aspect. Fig. 153.—Epliemerella tempora
. Bulletin. Natural history; Natural history. 62 Illinois Natlral History Survey Bulletin Vol. 26, Art. 1 filamentous gills absent on first ab- dominal segment - Platclike gills present on abdominal seg- ments 4-7, figs. 162-164; filamentous gills present on first segment 4 Frontal shelf of head without such a notch 8 I'Vonta! shelf with a pair of small, triangu- lar, lateral projections, fig. 156 1. lata. 157 ?S Fig. 151.—Ephemerella hicolor, head of mature male nymph, anterior aspect. Fig. 152.—Epliemtrrlla hicolor, head of mature female nymph, anterior aspect. Fig. 153.—Epliemerella temporalis, head of mature nymph, anterior aspect. Fig. 154.—Epliemerella cornuta, head of mature nymph, dorsal aspect. Fig. 155.—Epliemerella -dalkeri, head of mature nymph, dorsal aspect. Fig. 156.—Epliemerella lata, head of mature nymph, dorsal aspect. Fig. 157.—Epliemerella cornutella, frontal shelf of head of mature nymph, dorsal aspect. 2. Fore femur not enlarged and toothed on anterior margin, figs. 161, 172, Fore femur enlarged and toothed on anterior margin, fig. 160 6 3. .Apical half of caudal filaments clothed with short spines, fig. 172; maxillary palps reduced or entirely wanting, figs. 167, 169 10 Apical half of caudal filaments clothed with long hairs, fig. 173; maxillary palps well developed, fig. 168 14 4. (lill on abdominal segment 4 operculate, fiu. 164; maxillary palps wanting, fig. 169 5 Gill on abdominal segment 4 .semiopercu- late, figs. 162, 163; maxillary palps present, as in fig. 168 29 5. Occipital tubercles wanting in male, vestigial in female, figs. 151, 152 . 22 Occipital tubercles well developed in both sexes, although larger in females than in males, fig. 153 23 (fV/fLKERr Group) 6. Occipital tubercles present, as in fig. 153 2. tuberculata Occipital tubercles absent 7 7. Frontal shelf of head with a notch be- neath each antennal base, fig. 155 .. 3. walker! Frontal shelf with a pair of conspicuous, lateral horns, figs. 154, 157 9 9
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Keywords: ., booka, bookcentury1900, bookdecade1910, booksubjectnaturalhistory
