132 THOMAS SAY FOUNDATION 



low on the sides ; surface moderately rugose ; front and 

 hind margin convex ; angles broadly rounded ; a depressed 

 groove extends all around the margin. Legs dark brown ; 

 apical tarsal segment longer than the other two segments 

 combined; first segment longer than second. Wings sub- 

 hyaline or lightly infuscated; veins dark, not heavy; 

 venation as in PI. 15, fig. 6. 



Abdomen brown; cerci or tails dark, hairy, reaching 

 nearly to tip of wings; basal segments short, segments 

 beyond middle about three times as long as wide. 



Male. Ninth abdominal sternite produced and evenly 

 rounded behind and bearing a rounded, chitinized, knob- 

 like appendage; tenth tergite partly cleft; supra-anal 

 process broad and short, partly membranous; subanal 

 lobes unmodified. 



Female. Subgenital plate produced and emarginate in 

 the middle. 



Genotype, A", perdita Banks, the sole known species. 



Kathroperla perdita Banks. 



(Plate 15, fig. 6; plate 23, figs. 7, 8.) 

 1920. Kathroperla perdita Banks, Bull. Mus. Comp. Zool., 64:315. 



Length to tip of wings, male 20 mm.; expanse, male, 

 35 mm. ; length to tip of wings, female, 23-24 mm. ; ex- 

 panse, female, 38-40 mm. 



General color dark brown with yellow on head and 

 prothorax. 



Head very long, about as long as wide; the distance 

 from the hind margin of the eyes to the pronotum much 

 greater than the distance from the front margin of the 

 eyes to the anterior margin of the head. Color dark 

 brown with yellow in front of the ocellar triangle and ex- 

 tending back on the outer margin and along a ridge to 

 the posterior ocelli (in the specimen from California the 

 head is largely yellow except for a dark spot over the 

 ocellar triangle and a black margin behind the eyes) ; 

 tubercles very weak; no frontal ridge, two raised spots 

 in front and each side of the front ocellus; eyes very 

 small ; ocelli form an equilateral triangle, the hind ocelli 

 about as close to the eyes as to each other. Antennae dark 

 brown, the second segment almost as long as first ; palpi 

 dark brown. 



Prothorax about as wide as head; transversely oval, 

 much wider than long ; blackish brown with a median yel- 

 low stripe and a yellowish mark on the lateral margins; 

 front and hind margins rounded, sides convex or much 



