EEV. A. E. EATON ON EECENT EPHEMEEID.E OE MAYFLIES. 315 



Hiud wiug oblique, usually rather broad aud 



obtusely ovate, bi- or tri-uerved, with usually a small 



aud acute costal projection Baetis (p. 156). 



Hiud wing oblique, usually rather broad and 



oblong, tri-nerved, with several cross-veinlets in at least 

 the marginal area, aud with a large aud very obtuse 

 costal protuberance CaUibcBtis (p, 191). 



Siplilurus Type. 



37 Hind tarsus shorter than the tibia 38 



., Hind tarsus longer than the tibia 11 



38 .... Proximal joint of the hiud tarsus distinctly 



shorter than the next joint 39 



Proximal joint of the hiud tarsus hardly per- 

 ceptibly shorter than the next joint. Of every tarsus 

 one claw is bluot and the other hooked Ameletus (p. 210). 



Proximal joint of the hiud tarsus longer than the 



next joint. Tarsal claws all narrow and hooked. Hind 



wiugs minute Dijiteromimus (p. 213). 



39 .... Of every tarsus one claw is blunt and the other 



hooked Coloburus (p. 201). 



Claws of the hinder tarsi, aud usually of the fore 



tarsus also, all narrow and hooked •10 



40 .... Axillar region of the hiud wing ample, containing 

 numerous lono- branchlets of the 2nd Axillar nervure. 



Claws of the d fore tarsus peculiar in form .... Ch'wotojietes (p. 203). 

 Axillar region of the hind wing small aud nar- 

 row ; 2nd Axillar nervure of the same almost branch- 

 less Metamonius (p. 208). 



41 .... Proximal joint of the hind tarsus longer than the 



next joint. Tarsal claws all narrow aud hooked . . . SipJilurus {]}. 21-\>). 



Proximal joint of the hind tarsus likewise longer 



than the next joint. Of every tarsus one claw is blunt 



and the other hooked Ouiscigaster (p. 223). 



Bgetisca Type. 



42 .... Hind tarsus longer tliau the tibia ; its proximal 

 joint longer than the next joint. Of every tarsus one 



claw is blunt and the other hooked Bcstisca (p. 226). 



■ Atopopus Type. 



43 .... Axillar region of the hind wiug ample and with 



42* 



