THE WATER FLEAS (CLADOCERA) 



691 



ii (12) Reflexed antenna not reaching posterior margin of valves. 



Diaphanosoma brachyurum (Lieven) 1848. 



Eye pigment large; eye falling end of head. Color yel- 

 lowish-transparent. Length, , 0.8-0.9 mm.; o\ca. 0.4 

 mm. Common in marshes and weedy margins of lakes. 

 Very probably the next species is merely a limnetic vari- 

 ety of this. 



FIG. 1054. Diaphanosoma brachyurum. 



12 (n) Antenna when reflexed reaches or exceeds posterior margin of valves. 



Diaphanosoma leuchtenbergianum Fischer 

 1850. 



Eye not filling end of head, pigment small. 

 Color hyaline. Length, ? , 0.0-1.2 mm.; $ , to 

 0.8 mm. Common in open waters of lakes. 



FIG. 1055. Diaphanosoma leuchtenbergianum. 



13 (10) Spines on post-abdomen 14 



14 (17) Eye dorsal, far from insertion of antennule and optic ganglion. No 



rostrum Latonopsis Sars 1888 . . 15 



No tongue-shaped process on ventral side of head, or antennary expansion. Otherwise much 

 like Latona parviremis. Posterior margin of valves with very long setae (often lost). $ with 

 long antennule, copulatory organ, and hook on first foot. 



15 (16) Shell gland drawn out into very long posterior loop. 



Latonopsis occidentalis Birge 1891. 



Post-abdomen with about 9 small anal spines. Color yellowish-trans- 

 parent. Length, ? , to 1.8 mm.; $ , ca. 0.6 mm. New England to Colorado 

 and Texas; in weedy pools and lakes. 



FIGS. 1056, 1057, b. Latonopsis occidentalis. 

 (See also Fig. 1057.) 



O5 MM. 



