CAENIS. 55 



side, with three fuscous points; setae long; wings whitish, the cos- 

 tal margin obscure. (From Say's description.) 



Length of body 3 millim. 



Nab. Indiana, 4th September (Say). 



2. C. diminuta. 



Caenis diminuta Walk.! Catal. 584, 14. 



Fulvous; abdomen pale testaceous, setae long, white ; feet white, 

 anterior ones banded twice or thrice with black ; wings whitish, 

 veins white, the costal margin blackish. Male. (From Mr. Walk- 

 er's description.) 



Length of body 3 millim. Alar expanse 6 millim. Length of 

 setae 12 millim. 



Hob. St. John's Bluff, E. Florida (Doubleday). 



This species is allied to C. lactea of Europe. 



3. C. arnica ! 



Caenis arnica Hagen! 



Head and prothorax fulvous, banded with black ; antennae whit- 

 ish ; mesothorax brassy-fulvous ; feet whitish, anterior ones much 

 longer, cinereous, the femora obscurer, posterior femora with a 

 spot above upon the apex, black ; abdomen pallid, varied with 

 gray upon the back, segments with the apex and sides marked with 

 black ; setae white ; wings opaque, whitish-gray, the two costal 

 veins black. (Male Imago.) 



A male, taken at the same place, differs in its colors ; the head 

 is yellow banded with black ; the thorax yellow ; the feet white ; 

 the anterior femora and tibiae have the apex gray ; the abdomen 

 is whitish-yellow, g Imago. It may be a distinct species. 



Length 2 millim. Alar expanse 4 millim. Length of setae 6 

 millim. 



Hob. Pennsylvania (Zimmerman, Berlin Museum), 



Is it C. hilaris? Say? he describes the eyes as double: are 

 they really so ? The genus Caenis has the eyes simple ; neverthe- 

 less the description best suits Ephemera hilaris Say. 



FAM. Y. ODOXATA. 



Antennas short, setiform; mouth not furnished with palpi; 

 wings flat, reticulated; tarsi with three articles; second ven- 



