EPHEMEBINJE. 555 



Subimago. Pale testaceous : abdomen twice the length of the 

 thorax : setae white, twice the length of the body : legs white : 

 wings whitish, nearly limpid ; veins white. Length of the body 

 3 3J lines; of the setae 7 lines; of the wings 7 lines. 



Var. Head piceous above: prothorax with two short brown 

 streaks : disk of the mesothorax tawny. 



a c. Para. From Mr. Stevens' collection. 



21. PALINGENIA. VITREA. 



Testacea ; femora fusco subnotata ; alee albidce, subopacce, venis 

 testaceis. 



Ephemera vitrea, Barnston, MSS. 



Subimago. Testaceous : abdomen hardly twice the length of 

 the thorax: an indistinct brownish mark on each femur: wings 

 dingy whitish, slightly opaque ; veins testaceous. Length of the 

 body 3 lines ; of the wings 12 lines. 



a. St. Martin's Falls, Albany Elver, Hudson's Bay. Presented by 

 Dr. Barnston. 



Genus 4. BAETIS. 



Oculi maris approximati, simplices. Pedes bene determinati. 

 Setae caudales duae. Alae reticulatae, quatuor, venis plurimis. 

 Larva valde depressa, repens, non subiens, cauda simplici. 



Baetis, Leach ; Steph. ; Curt. ; Burm. ; Pictet. 

 Ephemerae bisetae, Zett. 

 Baetidae, Newman. 



Eyes simple in both sexes, but much largest in the male where 

 they are generally only separated by a very small interval : wings 

 four, with numerous cross-veins ; fore-wings long and narrow ; hind- 

 wings almost as long as one-fourth of the fore-wings, with a com- 

 plete neuration and an angular costal border : abdominal tentacula 

 large and much curved ; internal appendages short and quadrate : 



