THE WATER FLEAS (CLADOCERA) 



6<>> 



29 (28) Rostrum and antcnnules pulcx-Ukc; p.^st-abdomen tapered not 

 ^^^^^^^ Ddpliniu psitUirea iH:iird)\hso. 



General form hke D. macui hut smaller an.l more tmn*. 

 parent. 1 ost-alxlonun taiK-riiiK. not sinuate, with aU.ut 10 

 anal teeth anc many Justtrs <.f sh..rt. line hair>. Claws »,ih 

 two pectens the <iistal having ahout 15 teeth. Unicth. 9 to 

 2.8 mm. besides spme of 0.8 mm.; ^ , to 1.8 mm. NcbraJt*. 

 m pools. ^^ 



Fig. 1063. Daphnia psittacca. note small <*ci.i,.i... , ,.,i,u» 

 lx;hin(l |jrimary. 



0.5 MM 



30 (27) Secondary fornix rudimentary or very small. Tcx-th (.f distal (k-, t.n 



rarely exceeding 10, usually fewer : 



31 (32, 33) Ocellus present; head not hclmeted. 



Daplinia pulcx (de Gecr) 1778. 



I MM. 1 



B<Kly stout and 



• vn; r.-ually not 

 .:: ;■..:...! An- 

 i.:.;.it - \in.- small. 

 the apc.x apiK.arinK a.s lupiliar «»n |k»- 

 terior surface of rostrum iVist ab- 

 domen without sinus; anus at end; 

 anal spines iJ-17. Summer ejacs 

 numerous; ephippium with two cfocs 

 plattd nearly vertically 



Color red to yellow-brown, vcr>' variable. 

 Length, 9. to 2.5 mm. In pt>ols and bkcs in 

 all regions; numerous varieties. 



Fig. 1064. Daphnia puUx. 



D. pulex includes a preat number of 

 varieties, many of which havr l>em de- 

 scribed as distinct sjx-iies I' '■ nl 

 will be safe in assijcnins to / :. .c. 

 heavy-bodied forms with I- as. 

 In many cases the identitn.ainjn oi the 

 variety is more imix)rtant than that of the 

 species, but the varieties have n«>t l>ccn 

 worked out for this country. A few may 

 be noted: 



Figs. 1065.1066. 



Daphnia puUx. post-abdoiDCO 



ami claw. 



Var. pulicaria Forbes. A semi-trans- 

 parent limnetic form. vcr>- close to pmUx^ 

 but more sli>;htly built. Lon>: Hiinc. 



Common in lakes. 



V'ar. dathratii Forbes. Only i; anal 

 spines. IVcten with j-4 larpe tcrlh. 

 Yellowstone. 



\ar. mitttirhaha derrick "^'"^ ' ' ■'- 

 over heart in adult 9 ^ '^'f' 

 and younK'- Minnes.t.T nv. 

 Var. ohtusii Kurz 

 absent. 9-10 anal spines. Rostrum long and pointed. Mainr. W im-mm 



Var. curvirostris Eylmann. Rostrum very long and 

 valves. Nebraska, California. 



ontinutd l).uk\\ 



