CAENIS. 55 



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

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



Length of body 3 millim. 



Hob. 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 

 seise 12 millim. 



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



This species is allied to G. lactea of Europe. 



3. C. arnica! 



Caenis arnica Hagen! 



Head and prothorax fulvous, banded with black ; antennas 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 ; setas 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 ; tbe feet white ; 

 the anterior femora and tibiaa 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 seise 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. 



Antennae short, setiform; mouth not furnished with palpi; 

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



