556 EPHEMERIN.E. 



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

 dian bristle. 



1. Baetis flominum. 



Corpus fulviun, fusco maculatum ; caput mediocre ; oculi maris 

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

 lina, aut basi subtincta, areola costali pallida invaria. 



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



Allied to Ephemera S chaff. 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 

 valde t distinctis notata, marginibus fuscis ; alee hyalina, 

 areola costali basi hyalina apice colorata. 



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



Mand. vi. 63, 2. Pictet, Hist. Nat. Neur. Eph. \67, 2, pi. 



20, f. 1. 

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



pi. 18, f. 1 — 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. Mag. 1834, 120. 



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



a, b. England. 



3. Baetis cyanops. 



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

 subtincta, areola costali basi hyalina apice colorata. 



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



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



Switzerland. 



