. Bulletin. Natural history; Natural history. 90 ILLINOIS NATURAL HISTORY SURVEY BULLETIN Vol. 21, Alt. i ifiiiovecl from one another than from com- pound cjes. Pronotum approximately quadrangular, much broader than long, diameter at front angles apparently greater than at hind angles, front margin bowed, front angles appear sharp, a distinct pattern of raised rugosities on surface each side of median stripe. Legs with first tarsal segment mucii longer than second and third together, the second much shorter than Fig. 78.—Diclyoplerygella knowltoni. Wings, fig. 78, with venation as in i
. Bulletin. Natural history; Natural history. 90 ILLINOIS NATURAL HISTORY SURVEY BULLETIN Vol. 21, Alt. i ifiiiovecl from one another than from com- pound cjes. Pronotum approximately quadrangular, much broader than long, diameter at front angles apparently greater than at hind angles, front margin bowed, front angles appear sharp, a distinct pattern of raised rugosities on surface each side of median stripe. Legs with first tarsal segment mucii longer than second and third together, the second much shorter than Fig. 78.—Diclyoplerygella knowltoni. Wings, fig. 78, with venation as in illustration, tip of wing with branches of radial sector somewhat turned upwards. Wing membrane stained with brown and veins dark brown. Hind wing with eight branches of anal veins reaching margin of wing. Abdomen, fig. 78, with tergites normal except for small areas on terminal segments which are heavily covered with spinulae; tenth tergite not cleft for reception of the supra-anal process. Ninth sternite not pro- duced and recurved upwards, without a disklike pad. Subanal hook very peculiar, prolonged backwards as a projection from bodv, the two plates together when viewed from above or below forming a mushroom- shaped structure. Length to tip of wings, 15 mm.; lengtli to tip of abdomen, 12 mm. No gill rem- nants found on any body area. Holotype, male.—Loyun, Ut;ih: luiic 23, 1929, G. F. Knowlton. " I his new species is unique among North American stoneflies described to date b\' virtue of the peculiarly prolonged subanal plates, fig. 78. Tentatively, pending the collection of fresh material and the female, it is placed in the genus Dictyopteryyellu Klapalek (1904). This genus is character- ized among other things by the peculiar subanal plate which in such a European species as D. uaiiseni Kempny is very sug- gestive of knrju'ltoiii as here described. Dictyopterygella is placed by Klapalek in the Perlodidae. According to the author's studies the Perlodidae of North A
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Keywords: ., booka, bookcentury1900, bookdecade1910, booksubjectnaturalhistory
