60 



Fresh-water Biology 



6 — With 10 or more pairs of trunk limbs 7 



— With 4 to 6 trunk limbs; shell bivalved, generally covering body but leaving head 

 free Cladocer a — 13 



7 — Without shell; paired eyes pedunculate. The fairy shrimp, etc Anostraca — 8 



— ^With shell; paired eyes sessile 10 



8 — Clasping antennae of male biarticulate. Frontal appendage present — (Chiro- 



cephalidae) 9 



— Clasping antennae of male triarticulate — (Streptocephalidae) Streptocephalus 



9 — Frontal appendage of male rather short Eubranchipus 



— Frontal appendage of male long and vertical Branchinela 



10 — Shell resembling that of a small clatn Conchostraca — 11 



— Shell not clam like Notostraca 



11 — Shell spheroidal without lines of growth — (Limnetidae) Limnetis 



— Shell with concentric lines of growth (Limnadiidae) — 12 



12 — Shell with 4 to 5 lines of growth Eulimnadia 



— Shell with 18 to 22 lines of growth. Pediculated dorsal organ on front of head — 

 Limnadia; no dorsal organ present Estheria 



13 — Shell restricted to the brood chamber; feet flattened and jointed — Gymnomera — 

 Polyphemus pediculus (fig. 13); Leptodora kiudti (fig. 15). 

 — Shell covering the body; feet not distinctly jointed Calyptomera — 14 



14 — Six pairs of feet; foliacious Ctenopoda — 15 



— Five or six pairs of trunk limbs, first two pairs more or less prehensile — Anomopoda . 19 



{Continued on page 62) 



1, Daphnia 



2, Sida 



3, Nauplius 



4, Camptocercus 



5, Simocephalus 



6, Ceriodaphnia 



7, Eurycerus 



8, Acroperus 



9, Macrothrix 



10, Chydorus 



11, Bosmina 



Plate 24. Crustaceaus 



12, Diaphanosoma 



13, Polyphemus 



14, Alonella 



15, Leptodora 



16, Diaptomus 



17, Limnocalanus 



18, Cypridopsis 



19, Canthocamptus 



20, Cyclops 



21, Eubranchipus 



Acroperus, 8 

 Alonella, 14 

 Bosmina, 11 

 Camptocercus, 4 

 Canthocamptus, 19 

 Ceriodaphnia, 6 

 Chydorus, 10 

 Cyclops, 20 

 Cypridopsis, 18 

 Daphnia, 1 

 Diaphanosoma, 12 



Diaptomus, 16 

 Eubranchipus, 21 

 Eurycercus, 7 

 Leptodora, 15 

 Limnocalanus, 17 

 Macrothrix, 9 

 Nauplius, 3 

 Polyphemus, 13 

 Sida, 2 

 Simocephalus, 5 



