PLECOPTERA OF NORTH AMERICA 183 



Male. Ninth ventral segment with a transverse oval, 

 smooth hammer. Genital hooks somewhat flattened, re- 

 curved, rather bluntly pointed. Prickles on the dorsal 

 side of segments 9 and 10 numerous, on the 9th contin- 

 uous and on the 10th interrupted in the middle by an 

 area of long appressed hairs. 



Female. Subgenital plate oval, rounded and entire on 

 the tip, overlapping the basal half of the 9th sternite and 

 followed on that sternite by two small, round, brownish 

 spots at the sides. 



Distribution. — Type locality, Pennsylvania. 



Pennsylvania, Washington Co.; Jeannette, July 8, 



1904 (H. G. Klages). 

 District of Columbia, Washington. 

 North Carolina, Morgantown, 1877 (Morrison). 

 Tennessee, Knoxville, May and June, 1889. 

 Maryland, Stubblefield Falls, Potomac River, June 

 3, 1902. 



Acroneuria trijuncta Walker. 



(Plate 28, fig. 24; plate 30, fig. 14.) 

 1852. Perla trijuncta Walker, Cat. Neur. Ins. Brit. Mus., p. 153. 

 1022. Acroneuria trijuncta Needham and Claassen, Can. Ent., 54:252. 



Length to tip of wings, female, 30 mm. Expanse, 53 

 mm. 



Color yellowish fuscous. Head wider than prothorax ; 

 a dark brown spot over the ocellar triangle, rounded be- 

 hind and on each side -produced toward the base of the 

 antennae ; frontal M-ridge very faint, yellowish ; frontal 

 tubercle moderately distinct ; clypeus light brown ; area 

 beside the eyes and behind ocellar triangle yellow, some- 

 what infuscated on the hind margin. The ocelli form 

 an equilateral triangle ; hind ocelli somewhat closer to 

 each other than to the eyes, inner margin with 

 a black pigment ring. Antennae brown, lighter under- 

 neath ; first palpi light brown. 



Prothorax narrower than head ; yellowish, somewhat 

 darker around the border; wider than long, narrower be- 

 hind, especially the posterior third; front margin evenly 

 rounded; hind margin nearly straight; sides somewhat 

 angulate; front angles subacute; hind angles narrowly 

 rounded ; surface moderately rugose. Meso- and meta- 

 thorax yellowish, somewhat darker in the middle ; under- 

 neath pale yellow. Legs yellow; femora above with a 

 blackish broad mark just before the distal end; tibia 

 brown at the basal end; tarsi darker toward the tip. 



