With sixteen or seventeen segments in the flagcllum of the second antenna 

 Cyzicus Adouin 

 (Estheria Riiippell (part) ) 



9. Second (large) antennae of males threc'jointed 



Strcptocephalus Baird (of Family Streptocephalidae) 

 Second antennae of males twO' jointed 10. 



10. Males without processes between the antennae (frontal appendages); 



Fa.mily Branchmectidae 11. 



With frontal appendages between antennae of males or with a flattened 



process from the inner side of the base of each second antenna of 



males; Family ChirocephaUdae 12. 



11. With eight segments to apparent abdominal region; found in salt lakes 



or salt evaporating basins 

 Artemia Leach 

 With nine segments to apparent abdominal region; fresh-water animals 

 Branchinecta Verrill 



12. Most of abdominal segments fused together 



Thaynnocephahis Packard 

 Abdomen completely segmented 13. 



13. Male frontal appendages long and irregularly twisted together 



Branchinella Sayce 

 Male frontal appendages short or more regularly coiled 14. 



14. Male frontal appendages long and closely coiled 



Pristicephalus Daday 

 (Euhranchipus Verrill (part ) ) 



Male frontal appendages shorter 

 Euhranchipus Verrill 



GENERAL REFERENCES 



Caiman, W. T. 1909. Crustacea. Lankester's Treatise on Zoology, Part 7, 



Fasc. 3. London and New York. 

 Packard, A. S. 1883. A Monograph of the Phyllopod Crustacea of North 



America, etc. 12 Ann. Rept. U. S. Geol. Surv. 

 Pearse, A. S. 1918. The Fairy Shrimps (Phyllopoda) Chap. 21 in Ward 



and Whipple's "Fresh-water Biology". John Wiley 6? Sons. New York. 



KEY TO THE PRINCIPAL GENERA OF CLADOCERA 

 OR WATER FLEAS 



Body not enclosed in a shell (shell covering only the egg case) 2. 



Body enclosed in a shell (head usually protruding outside) 3. 



With four pairs of flattened feet; Family Polyphemidae 



Polyphemus O. F. Miiller 

 With six pairs of cylindrical feet; Family Leptodoridae 



Leptodora Lilljeborg 



179 



