Petersen, New and little-known species of Ephemerida fr. Argentine. 335 



and 9 with a dark border behind. Venter pale yellowish with 

 an indistinct , darker oblique stripe on each side of segments 

 2 — 8. Setae white. Forceps and penis yellowish. Fora legs 

 dark violet greyish ; tarsi 

 distinctly 5 jointed, and the 

 1«*, 2'^'^ and 3*'^ Joint dila- 

 ted in the middle. Wings 

 vitreous with faint violet 

 tinge. Subcosta and radius 

 in the fore wings dark vio- 

 let grey to a little beyond 

 the middle. The other 

 longitudinal nervures and 

 the greater part of the 

 transversa veins greyish 

 yellow. 



Length 13 mm; wing 

 13 mm ; setae 30 mm. 



One male, preserved in 

 alcohol , was collected to- 

 gether with Gampsurus Jör- 

 genseni. In the nervature 

 of wings the species agrees 

 with Campsurus albifilum 

 Walk., biit it differs in the 

 shape of forceps and penis. 



Fig. 3. Campsurus argentinus. 



a Forceps and penis, seen from tlie 



ünderside, h seen from the side. 



4. Thr aulus Valdemari n. sp. 



Upper part of eyes dark brown , lower black. Thorax dark 

 brown with a median yellow - brown band. Abdomen dorsally 

 dark greyish brown with the tip of each segment yellowish 

 brown. Setae greyish brown withont distinct annulations. Fore 

 femora and tibia brown, tarsus paler. Forceps (shrivelled up by 

 the spirit) dark brown at the base , yellow -brown towards the 

 apex. Wings with an intense brown tinge. The costal and sub- 

 costal areas and the nervures blackish brown as in Choroterpes 

 Picteti. 



Length 6 mm; wing 7,5 mm; setae 10 — 13 mm, the middle 

 one is the longest. 



The description is made from a single specimen , a male, 

 preserved in alcohol and collected at Bompland in Misiones. 



The species is easily recognized by the intense brown tinge 

 on the wings. I have placed it in Thraulus , though there is 

 some difference in the nervature in the bind wings and in the 



