Petersen, New and little-known species of Ephemerida fr. Argentine. 339 



7. Thraulus misionensis n. sp. 



Thorax dark brown above , paler at the sides. Abdomen 

 dorsally reddish brown with the front border of segments 2 — 8 

 translucent white. At the sides of dorsum of segments 3 — 7 a 

 triangulär whitish yellow spot extends backwards from the whitish 

 border ; the spot is enclosed by two fine dark brown longitudinal 

 lines, which converge to a point in the hind border of the Seg- 

 ment. The lateral margin of segments 2 — 8 with a fine dark 

 brown longitu- 

 dinal line. The 

 venter yellowish 

 brown. Penis 

 yellowish white. 

 Forceps dark 

 brown. Setae 

 yellow with fine 

 black annula- 

 tions. Femora 

 and tibia of in- 

 termediate and 



Fig. 8. Thraulus misionensis. 

 a One of the forceps limbs and the penis, h hind wing. 



hind legs light brown ; knees blackish brown. Tarsi paler than 

 femorae and tibiae. Fore wings hyaline with a yellowish finge in 

 the marginal area. The nervures and cross veins yellowish brown 

 and darker than the membrane. The costal area without cross 

 veins at the base and with 10 cross veins in the pterostigma- 

 tical region. The subcostal area with two cross veins in the 

 inner half. 



Length 5,5 mm ; wing 7 mm ; setae circa 10 mm. 



The description is made from two males from Bompland, 

 prepared in alcohol. The specimens have lost their fore legs. 



8. Callib aetis trif as ciatus n. sp. 



Fig. 9. Fore wing of Callihaetis trifasciatus. 



23* 



