PHTLLOPODA 



337 



G. testudinaria (Fischer) (Fig. 524). Length .7 mm.; shell reticu- 

 late: eastern and central America; Europe. 



4. ALONA Baird. Body minute, more or less oval or rectangular 

 in form, with small antennae, the second having 8 setae; with a coiled 

 intestine: numerous species, which are very variable in form. 



A. quadrangularis (0. F. Miiller) (Fig. 525). Body oval or quad- 

 rangular; pigment spot smaller than eye, abdomen very broad and short; 



Fig. 523 Fig. 524 Fig. 525 



Fig. 523 Acroperus harpae (Herrick). Fig. 524 Oraptoleberis testudinaria (Siissw. 



F. Deut.). Fig. 525 Alona quadrangularis (Siissw. F. Deut.). 



shell smooth and yellowish in color; length .9 mm.: widely distributed 

 over eastern and central America; Europe. 



5. PLEUROXUS Baird. Front end of head long and pointed, forming 

 a beak; shell with an arched dorsal edge; intestine coiled: numerous 

 species. 



P. procurvns Birge (Fig. 526). Hinder margin of shell denticulate; 

 beak curved upwards, forming a hook; length .5 mm.: eastern and 

 central America. 



6. CHYDORUS Leach. Body minute, spherical, with a long curved 

 beak; antennae short; intestine coiled: 8 species. 



2 



Fig. 526 Fig. 527 Fig. 528 



Fig. 526 Pleuroxus procurvus (Herrick). Fig. 527 Chydorus sphericus (Herrick). 

 Fig. 528 Polyphemus pediculus (Siissw. F. Deut.). 1, first antenna ; 

 2, second antenna ; 3, brood sac ; 4, abdomen. 



C. sphericus (0. F. Miiller) (Fig. 527). Shell reticulated; pigment 

 spot almost as large as the eye ; color yellowish ; length .4 mm. : widely 

 distributed over eastern and central America; Europe. 



FAMILY 5. POLYPHEMIDAE. 



Carapace not enclosing the legs and abdomen, and serving only as 

 a brood sac; 4 pairs of legs which lack the flattened respiratory pro- 

 jections of other Pliyllopoda; abdomen slender, with 2 long caudal 

 spines; head very large, with a single large eye and large second anten- 

 nae: 4 genera. 



