562 EPHEMEKIN/E. 



23. BAETTS INTEEPUNCTATA. 



Albida ; caput viridescens ; abdominis segmenta marginibus pos- 

 ticis nigns. 



Baetis interpunctata, Say, Journ. Acad. Nat. Sci. Phil. viii. 41, 1. 



Yellowish white, tinged with green : head rather prominent, 

 yellow-green ; vertex with a lateral hlack point: eyes with a longi- 

 tudinal black line : ocelli distant, each with a black orbit ; anterior 

 one less than half the size of the others: front with a black angular 

 line under the antennae : seta of the antennae black: prothorax with 

 a black line on each side : thorax somewhat brownish : abdomen 

 with the hind borders of the segments black : setae immaculate : 

 legs greenish ; anterior femora with two blackish bands ; hind pair 

 with dusky tips : wings greenish on the fore border, with black 

 transverse veins, and a distinct black abbreviated longitudinal line 

 on the middle, between the third and fourth veins ; the small black 

 spot on the middle of the costal border is very obvious: tip of the 

 abdomen more or less ferruginous. Length nearly three-tenths of 

 an inch. 



Indiana. 



24. BAETIS ARIDA. 



Fuscescens ; pedes posteriores et setce alba. 

 Baetis arida, Say, Journ. Acad. Nat. Sci. Phil. viii. 42, 2. 



Reddish brown, with dusky incisures : head rather prominent, 

 whitish, varied with ferruginous ; vertex with a small black spot on 

 each side of the orbit : eyes rufous, with a whitish vitta : ocelli pro- 

 minent, approximate ; anterior one nearly as large as the others : 

 fore-tibia3 whitish, obscure at each end ; posterior legs and setae 

 greenish white. Length fths of an inch. 



Indiana. 



25. BAETIS VEKTICIS. 



Flavido-alla ; caput ferrugineum ; thorax ferrugineo bivittatus. 

 Baetis verticis, Say, Journ. Acad. Nat. Sci. Phil. viii. 42, 3. 



