50 NETJROPTERA OP NORTH AMERICA. 



short pile, a little longer than the body; feet whitish, femora with 

 a medial and apical fuscous band ; wings hyaline, veins fulvous ; 

 anterior ones with the apex of the costal margin fulvescent. 



I;ength of body 8 millim. Alar expanse 24 millim. Setro 24 

 millim. 



JIah. North America (Zimmerman) ; St. Martin's Falls (Barn- 

 ston). 



The specimens described by Mr. Walker are a female and sub- 

 imago, not males as "Walker contends, and, perhaps, belong to a 

 different species ; Burraeister's species is perhaps a subimago, and 

 it may be of the preceding species. 



17. B. basalis. 



Baetis basalis Walk. Catal. 565, 31. 



Pitch-black ; antenna3 whitish ; abdominal segments margined 

 with testaceous; setae whitish, the incisures annulated with black, 

 twice as long as the abdomen ; anterior wings hyaline, the costal 

 veins clouded with fuscous, a middle marginal fuscous nebula; pos- 

 terior wings fuscous, their apex hyaline. (From Walker's descrip- 

 tion.) 



Length of body 12 millim. Alar expanse 28 millim. Set® 22 

 millim. 



Hub. Lake Winnipeg (Richardson). Is it not B. luridipennis'^ 



18. B. noveboracana. 



Ephemera noveboracana Lichtenstein, Catal. Mus. Holthuisen 1796, III, 

 193, 52. 



Bisetous; wings fuscescent, the hind ones smallest; the abdomen 

 fuscous, margined with luteous. (From the description of Lichten- 

 stein.) 



Hah. New York. Is it not B. laridipennis'^ 



19. B. tessellata! 

 Baetis tessellata Hagen I 



Luteous ; mesothorax each side with a fuscous line ; abdomen, 

 upon the segments, superiorly each side, with two fuscous triangu- 

 lar spots; setae — ? feet luteous, tarsi at the apex fuscous; wings 

 opaque, gray, ciliated, veins lurid, many quadrangular, hyaline 

 spots, posterior wings very small. Female, subimago. 



Length of body 16 millim. Alar expanse 26 millim. 



