756 FRESH-WATER BIOLOGY 



5 (6) Abdomen of female not distinctly flexed to the right. Terminal 



setae of furcae equal. 



Epischura nevadensis Lilljeborg 1889. 



Found in the mountain lakes of the western United States. 

 Length of female, 2 mm. 

 Length of male, 1.7 mm. 



Fig. 1 1 74. Abdomen oi male Epischura nevadensis. X 24. (Original.) 



6 (5) Abdomen of female distinctly flexed to the right, the external 



furcal setae much larger than the others. 



Epischura lacustris Forbes 1882. 



Common in the Great Lakes and other large bodies of water in 

 the central and eastern United States. 



Length of female, 1.78 mm. 

 Length of male, 1.38 mm. 



Fig. 1 1 75. Abdomen of male Epischura lacustris. X 49. (Original.) 



7 (4) Endopodites of second, third, and fourth feet composed of two 



segments. Furcal rami elongated. 



Eurylemora affinis Poppe 1880. 



Really a salt-water form, and commonly found in fresh water only when it is more or less 

 closely connected with the sea. Only one species is known in America in fresh waters and that 

 has been found in waters connected with the Gulf of Mexico and the Atlantic Ocean. 



Length of female, 1.5 mm. 



Length of male, 1.5 mm. 



8 (3' 73) Endopodites of first swimming feet composed of two segments, of 



third and fourth swimming feet composed of three segments. 

 Furcal rami short. Right fifth foot of male terminates in 

 a more or less sickle-shaped hook. . . . Diaptomus. . 9 



9 (22) Antepenultimate segment of the male right antenna without dis- 

 tinct appendage 10 



