. Bulletin. Natural history; Natural history. PRISON: STONEFLIES, OR PLECOPTERA, OF ILLINOIS 417 generic or subgeneric names of Klapalek seem to embrace or include this group when it is properh understood or segregated and hence a new generic name is 324 325 Hydroperla — new genus Type Perla crosbyi Needham ami Claassen = Hydroperla crosbyi (Needham and Claassen). The genus Hydroperla is apparently most closely related to Isoyenus. In the adults it is characterized by the following: three ocelli; forewings without crossveins in anal area and with a series of median and cubital cross
. Bulletin. Natural history; Natural history. PRISON: STONEFLIES, OR PLECOPTERA, OF ILLINOIS 417 generic or subgeneric names of Klapalek seem to embrace or include this group when it is properh understood or segregated and hence a new generic name is 324 325 Hydroperla — new genus Type Perla crosbyi Needham ami Claassen = Hydroperla crosbyi (Needham and Claassen). The genus Hydroperla is apparently most closely related to Isoyenus. In the adults it is characterized by the following: three ocelli; forewings without crossveins in anal area and with a series of median and cubital crossveins, fig. 183; first tarsal segment much shorter thnn third tarsal segment; cerci \(i\v^ and many segmented ; prothorax about as wide as head ; without nymphal gill remnants on sides or venter of thorax and ab- domen ; remnant of finger-like gills located near each side of outer basal corner of submen- tum ; species dominantly black ; of medium size wnth a body length usually more than 13 mm; males with tenth terglte deeply cleft; and females with a subgenital plate which usually is without any trace of a median notch, figs. 324, 325. Adults of Hydroperla may be separated from the other closely related genera belonging in Perlodidae as follows: 1.—From Perlodes by the absence of the network of irregular crossveins, figs. 183, 184, beyond the radial sector of the fore- and hind wings. 2.—From Isogenus in the females usually by the absence of a deep median notch on the posterior margin of the subgenital plate, figs. 324, 325, and in the males by the absence of dorsal humps on the apical abdominal tergites. The genus is characterized in the nymphs by the following: three ocelli; labium with paraglossae extending forward much farther than the glossae, the glossae deeply inset below and between the paraglossae so as to appear almost as basal segments of them, figs. 133, 134; venter of thorax without distinct, large, overlapping, shieldlike plates; with small finger-like gill
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Keywords: ., booka, bookcentury1900, bookdecade1910, booksubjectnaturalhistory
