6go 



FRESH-WATER BIOLOGY 



7 (8) Antennary expansion very large; no hepatic ceca. 



Latona setifera (O. F. Muller) 1785. 



Antennules of both sexes alike, bent, with large, hairy flagellum set on at angle, looking like 

 continuation of base. Color yellow; not transparent; old 9 often with brilliant colors in 

 late autumn. Length, $ , 2.0-3.0 mm.; $ , ca. 1.5 mm. Widely distributed, but never abundant, 

 among weeds in ponds and lakes. 



I MM. 



FIG. 1052. Latona setifera. 



8 (7) Antennary expansion small; hepatic ceca present. 



Latona parviremis Birge 1910. 



Antennule of 9 with basal part and long slender flagellum, like Latonopsis; of $ very long, 

 like other Sididae. Color yellow. Length, 9> to 2.5 mm.; $ , 0.8 mm. Northern Wisconsin, 

 Michigan, Maine; in weedy waters of lake . 



FIG. 1053. Latona Parviremis. 



9 (6) Without lateral expansion of antenna. . . 



10 



10(13) No spines on post-abdomen. . Diaphanosoma Fischer 1850 . . n 

 No rostrum, fornix, or ocellus. Antennule small, truncated; olfactory setae terminal, with 

 slender flagellum. Dorsal ramus of antennae 2-jointed; ventral 3 -jointed. Claws with 3 basal 

 spines. $ with long antennule; copulatory organ; hook on first r oot. 



