578 GEOLOGICAL SUEVEY OF THE TEREITOEIES. 



Family EPHEMEEINA. 



EPHEMERA. 



E. compar, sp. no v. 



Male imago. — Light-brown ; lieaclblackisb-brown ; antennae pale-yellow; 

 a broad, pale-brown, dorsal band on the thorax ; each side of the protho- 

 ra.x blackish ; abdomen above on each side with two, black, longitudinal 

 lines and two more in the middle of segments 6 to 9 ; last segment with 

 two large, ill-defined, black spots ; abdomen beneath on each side with 

 one black, longitudinal line ; penultimate segment with a large, quad- 

 rangular, black spot; setae very long, pale-brown, the articulations 

 hardly darker; appendices pale brown, long, arcuated on the tip; the 

 two apical joints short, the last shorter ; feet pale-brown ; the anterior 

 pair very long, black ; the femora brown ; fore-wings hyaline, with a 

 yellowish tinge ; veins dark-brown ; the apical half of the two costal 

 spaces dark-brown, and the basal half of the second costal space rather 

 fumose ; a series of four small, black spots in the middle of the wing 

 near to the costa, another spot near the base of the wing, and one near 

 the tip ; hind-wings of the same color, with a large apical brownish 

 band ; some of the veins in the middle of the wing finely clouded with 

 black. 



Length of the body, 15 millimeters ; alar expansion, 32 millimeters ; 

 length of the setse, 30 millimeters. 



ilabitat. — Foot-hills, Colorado (Mr. Oarj)enter). 



This species is very similar to U. lutea, Burm. {E. lineata, Eat.) ; as I 

 have seen only one male, I believe it to be more prudent not to identify 

 the American with the European species, the more so as some differ- 

 ences, though not important ones, are to be found. JEJ. lutea has the 

 third and fourth joints of the appendices of equal length, and together 

 two-thirds the length of the second joint. E. compar has the fourth joint 

 shorter than the third, and both together one-third the length of the sec- 

 ond joint. But as the only male of E. compar is dry, and as the measures 

 ior E. lutea are taken from living specimens, the differences may not be 

 certain. The discovery of E. compar fills a gap in the fauna of jSTorth 

 America. There are four species of European Ephemerce nearly related 

 to each other. Till now only three species were known in the North 

 American fauna representing three of the European species, and the dis- 

 covery of E. compar imitating the fourth European species makes the 

 parallelism of the Ephemerid fauna of both countries complete. 



As the other three American species were formerly not well described, 

 even some of them erroneously identified, I believe it is worth while to 

 give here a more detailed description of them. It is presumed that at 

 least two of them will be discovered within the area of country embraced 

 in this paper. 



E. decora, Hagen (Synop., 38, 1). 



3lale imago. — Luteous ; head in the middle, prothorax on each side, 

 dark-brown ; antennae pale ; abdomen above with four large, beneath 

 with two narrow, black lines ; setae pale, the articulations fine, brownish ; 

 appendages pale, the two last joints nearly equal in length, taken 

 together about half of the second joint in length ; anterior feet yellow ; 

 femora brown, darker at the tip ; tibiae at base and tip, tarsal joints at 

 tip, blackish; the other feet pale; fore-wings hyaline, with a faint yel- 

 lowish tinge, light-brown on the two costal spaces ; transversal veins 

 brown, faintly clouded near the costal margin and in the middle of the 

 wing ; some larger brown si)ots in the middle near to the costa, and one 



