36 



Fresh-water Biology 



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PLATE 14. CRUSTACEANS 



Length Disir. Waters Genera Figs. Length Distr. Waters 



30 W static Lynceus (6)t 10 G static 



15 G static Mysis 10 30 G static 



80 G both Palaemonetes . . . (14) § 40 S static 



12 W static Pontoporeia (7)11 H G static 



25 G static Potamobius 9 100 W both 



20 G static Streptocephalus . 4(11) 20 W static 



25 G static Syncaris 12-14 30 SW lotic 



9 G static Thamnocephalus 5 40 W static 



50 W static 



Genera Figs. 



Apus 2 



Asellus 1 



Cambarus (9)* 



Estheria 6 



Eubranchipus. . . 11 



Eucrangonyx ( 7 ) t 



Gammarus 7 



HyalleUa 8(7) 



Lepidurus 3(2) 



* Differs by having no gill on last thoracic segment, 

 t Differs by having tail-plate not cleft to base. 

 t Differs by having shell without lines of growth. 



§ Differs by having no terminal hair tufts on fingers. 



^ Differs by having last leg shorter than the one before it. 



