PLECOPTERA OF NORTH AMERICA 59 



adds a fourth to the length of the segment, and is set off 

 at either side by a fold half the length of the segment. 

 Segment ten divided middorsally as usual. The upper 

 edges of its side walls, deeply cleft and the hind angle 

 prolonged and curved forward in a very long ensiform 

 pointed genital hook, that is obliquely truncated at its tip, 

 not rounded as in P. signata. 



Female. The broad subgenital plate is produced to 

 cover half the ninth sternite and is divided into two 

 broadly rounded lobes that are separated by a shallow 

 acute notch. 



Egg. The egg of this species is oblong with ends sym- 

 metrically rounded. It is one-half wider than long. The 

 brownish shell is marked off in rather regular hexagons, 

 made of flat raised anastomosing ridges that are half as 

 wide as the areolations they inclose. There is a small 

 collar-like rim at the micropylar end, through which pro- 

 jects a transparent stalk: no cap seen upon this stalk in 

 the specimens that have been before us. 



Distribution. — Mount Rainier, Wash, (female type) ; 

 male neallotype herewith described from same ; Paradise 

 Valley, collected by E. P. Van Duzee July 17, 1920) ; 

 Waterton Lakes, Alta. (J. McDunnough) . 



Perlodes slossonae Banks. 



(Plate 7, fig. 19.) 



1914. Perlodes slossonae Ba-nks, Proc. Ac. Nat. Sei. Phila., p. 608. 

 1917. Arcynopteryx inornata Smith, Trans. Amer. Ent. Soc, 43:481. 



Length to tip of wings, 17 to 18 mm. ; expanse, 30 mm. 



Color brownish, the meso and metathorax blackish. 

 Head concolorous above, in so much that the usual frontal 

 tubercles and transverse M-line are scarcely visible. Ocelli 

 rather small, the rear ones about as close to the eyes as 

 to each other. Antennae and palpi dark brown. 



Prothorax chocolate brown with a broad yellow median 

 stripe that connects with the yellows on the rear of the 

 head. Disc a little wider than long, its sides rather 

 strongly rugose. Front angles sharp; hind angles 

 rounded. No gills. Legs brown. Wings with a scanty 

 and irregular network of -crossveins in the tip between 

 the costa and the branches of R2. First half of costal 

 area beyond the humeral free from crossveins. 



Abdomen blackish above, brownish beneath and lighter 

 toward the tip. Tails yellow at base, darkening toward 

 the tip; the segments darkening distally and clad with 

 lacy hairs. 



