No. 433 ] UNKNOWN EPHEMERID NYMPHS. 



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Gills single, lanceolate, bilobed, similar in outline to the first 

 stunted pair in Blasturus cupidus ; directed laterally, borne on 

 segments 1 to 7, and all alike except for the third, fourth, and 

 fifth pairs being slightly larger; margins of all somewhat 

 clothed with scattered hairs. 



Caudal setae all hairy on both sides, — sparsely so, however, 

 and then only at the joints ; angle of separation considerable ; 

 terminal third naked and lighter colored than the basal two- 

 thirds. Middle seta longest, length 5-6 mm. 



Legs rather small and weak, the third pair the longest; coxa 

 with a row of eight tiny spines ; femur abundantly spined ; tibia 

 and tarsus spined at angles and hairy, the hairs longest on the 

 tibia. This species seems to walk backward or forward with 

 equal facility. 



Total length 6-7 mm. (figure enlarged x 6); greatest width 

 1.1 to 1.5 mm. 



These were taken the afternoon of May 24 and were fully 

 grown, but owing to the cool weather none emerged until 

 May 29, when one emerged ; the next day (May 30) two others 

 emerged, and the first specimen molted his subimago accoutre- 

 ments and became a full-fledged ephemerid. 



This is the only known species from the United States, and 

 the only recorded locality as far as I know, although Eaton in 

 his revision states that he has seen a specimen belonging to 

 this genus from New Hampshire. 



Blasturus cupidus Say. 



This is one of the commonest spring May flies of the eastern 

 states. Imagos have been recorded from the following New 

 Jersey localities : Fort Lee, Staten Island, Caldwell, Westville, 

 and Jamesburg. The full-grown nymphs were common 

 beneath the floating debris around the pond margins during 

 the last week in March and the first week in April. On 

 May 17 none were to be found. 



Nymphs stout, widest across mesothorax (about 3 mm.), 

 total length 12 to 13 mm., color dark ; antennae about half as 

 long as body (or 6 mm.) ; legs comparatively strong, minutely 

 spined throughout. Comparatively slow swimmers, but active 



