94 THOMAS SAY FOUNDATION 



lies the black 5-rayed chitinous base of the supra-anal 

 process behind which a pair of ( ) -shaped brownish para- 

 genital plates encircle the tip of that process. 



Distribution. — California; a single male specimen from 

 Fieldbrook, Calif., May 30, 1903 (H. S. Barber, in U. S. 

 National Museum). 



Perla duplicata Banks. 



(Plate 18, figs. 5, 6.) 

 1920. Perla duplicata Banks, Bull. Mus. Comp. Zool., 64, No. 3:316. 



Length to tip of wings, male, 13-15 mm. ; female, 16-17 

 mm. Expanse, male, 24-26 mm.; female, 27-29 mm. 



General color brown, with infuscated wings and with 

 a median yellow stripe on prothorax. Head yellowish 

 with an infuscated spot over the ocellar triangle ; also 

 darker on the clypeus and behind the eyes ; frontal ridge 

 low, indistinct ; lateral tubercles not prominent ; ocelli 

 small, the hind ocelli a little closer to the eyes than to each 

 other. Antennae brown. 



Prothorax chocolate brown, with a wide median yellow 

 stripe and sometimes a little paler on the sides ; narrower 

 than the head, wider than long; narrowed behind; angles 

 rather sharp ; front and hind margins somewhat convex ; 

 surface moderately rugose. Legs brown, tibiae and tarsi 

 darker; a narrow, transverse, black band at end of 

 femora ; first and second tarsal segments short, subequal, 

 third tarsal segment very long. Wings quite smoky ; sub- 

 costa ends much before the cord ; a series of costal cross- 

 veins before the end of subcosta and several beyond ; 

 radial sector with 3-4 branches. 



Abdomen yellowish, darker above ; tails yellowish to 

 brown. 



Male. Seventh and eighth abdominal sternites each 

 with a rounded, median, knob-like appendage, the one on 

 the seventh sternite much larger than the one on eighth ; 

 ninth sternite much produced and rounded behind ; tenth 

 tergite cleft behind on each side with a rounded, raised, 

 spinulose knob directed inward ; ninth tergite reduced to 

 a narrow collar ; supra-anal process normally retracted 

 within the tenth segment; when extended it consists of 

 two slender chitinous, recurved processes lying side by 

 side, each somewhat enlarged at the tip and basally sur- 

 rounded by a membranous sheath ; subanal lobes broadly 

 triangular, unmodified. 



Female. Hind margin of eighth abdominal sternite pro- 

 duced into a large, rounded subgenital plate which reaches 

 entirely across the ninth sternite. 



