556 EPHEMERIN.E. 



two tail-bristles of equal length, without any rudiment of the me- 

 dian bristle. 



1. BAETIS FLUMINUM. 



Corpus fulvum, fusco maculatum ; caput mediocre ; oculi mar is 

 approximati ; pedes immaculati, aut vix maculati ; alee hya- 

 lince, aut basi subtinctce, areola costali pallida invaria. 



Baetis fluminum, Pictet, Hist. Nat. Neur. Eph. 164, 1, pi. 16 19. 



Allied to Ephemera Schceff. Icon. Ins. Ratisb. pi. 229, 2, 3, and 



232, 4, 5. 



a, b. England. Presented by F. Walker, Esq. 

 c e. England. 



2. BAETIS VENOSA. 



Pallide castanea ; oculi nigri; abdominis latera lineis obliquis 

 valdej distinctis notata, marginibus fuscis ; alee hyalina, 

 areola costali basi hyalina apice colorata. 



Baetis venosa, Burnt. Handb. Ent. ii. 801, 6. Steph. III. Brit. Ent. 



Hand. vi. 63,2. Pictet, Hist. Nat. Neur. Eph. 167, 2, pi. 



20, f. 1. 

 Ephemera venosa, Fabr. Ent. Syst. ii. 70, 8. Deg. Ins. ii. 652, 4, 



pi. 18, f. J 4. Oliv. Enc. Meth. 418, 8. Latr. Hist. Nat. 



Ins. xiii. 97, 10. Zett. Ins. Lapp. 1045, 7. 

 Ephemera nervosa, Fabr. Sp. Ins. i. 384, 6. De Vill. Linn. Ent. 



iii. 22, 14. 

 Baetis dispar ? Curt. Brit. Ent. xi. pi. 484. Phil. May. 1834, 120. 



Steph. III. Brit. Ent. Hand. vi. 63, 1. 



a, b. England. 



3. BAETIS CYANOPS. 



Corpus angustum, fulvum ; oculi cyanei ; alee hyalince, aut basi 

 subtinctce, areola costali basi hyalina apice colorata. 



Schaff. Icon. Ins. Ratisb. 229, 2, 3, 239, 4, 5. 



Baetis cyanops, Pictet, Hist. Nat. Neur. Eph. 171, 3, pi. 20, f. 2. 



Switzerland. 



