PLECOPTERA OF NORTH AMERICA 79 



beneath. Head, yellowish brown with a diffuse brownish 

 spot covering the ocelli and a faint suggestion of a paler 

 triangle at the occiput. Antennae brown, paler at base of 

 flagellum. Palpi long, dusky. Eyes very prominent and 

 hind angles of head rather small. Ocelli a trifle nearer 

 to each other than to the eyes. 



Prothorax quadrangular with parallel sides a little 

 wider than long, with rather acute angles. Middorsal pale 

 stripe obscure, widened to rearward. Embossed markings 

 well distributed over the sides of the disc but faint and 

 ill-defined. Legs brown, pale beneath. Wings smoky 

 hyaline throughout, hardly darker along the costa, the 

 color due to close set brownish microscopic pubescence. 

 Costal crossveins few and very faint before the subcosta, 

 stronger in the apical space beyond. The 2nd and 3rd 

 anal veins of the fore wing arise close together from the 

 rear of the anal cell ; in the hind wing" the 2nd anal is 

 two-branched, the 5th anal three-branched, and the fusion 

 of veins Rs and M extends only one-sixth of the distance 

 across the wing disc. 



Abdomen yellowish brown, pilose. Tails of the same 

 color at base, darkening toward their tips and very pilose. 



Male. Abdominal segments normal to the 7th, which is 

 slightly extended apically on the ventral side in a low 

 broad lobe; 8 normal; 9 prolonged beneath into a sub- 

 genital scoop-like lobe that doubles its dorsal length. Seg- 

 ment 10 is cleft above in its apical half, and the rear 

 angles beside the cleft are produced into rounded flat very 

 hairy lobes that in contracted specimens overlap at their 

 tips. Beneath them lies a long pointed tip of a supra- 

 anal process inclined upward and blackish, and it is sur- 

 rounded by a pair of pale slightly protruded paragenital 

 plates. 



Female unknown. 



Distribution. — California. Four male specimens from 

 San Antonio Creek, Alameda County, California, May 21, 

 1922 (B. C. Cain), bearing Stanford University Collection 

 numbers "38-1, 2, 3, and 4." "38-2" is the holotype. 



Male holotype and a male paratype, in the Cornell Uni- 

 versity Collection. 



Perla crosbyi, new species. 



(Plate 11, fig. 4; plate 17, figs. 7, 8.) 



Length to wing tips, male, 21 mm. ; female, 23 mm. Ex- 

 panse, male, 42 mm. ; female, 45 mm. 



Colors yellow and brown with yellow tipped abdomen. 



