THE WATER FLEAS (CLADOCERA) 68q 



KEY TO NORTH AMERICAN FRESH-WA ri-R CLADOCERA 



1 (248) Body and feet covered by a bivalve shell. Feel in Kencral f.iiiaccou^ 



not plainly jointed. . . . Section A. Calyptomera 



2 (21) Six pairs of feet, all similar, except the last, and all foliaccous. 



Tribe L Ctenopoda 



3 (18) Shell of ordinary type. Antenna biramous in female, rami llaiim..,, 



the dorsal with numerous setae, both lateral and terminal. 



Family Sididak Baird 4 



Head large; cervical sinus present. Antennules large, movable, .\nlcnn.ic with terminal 

 setae only on ventral ramus. Eye large, with numerous lenses; ocellus small or a? ■ ' • .. 

 tine simple, usually with more or less distinct median cecum or cnlargt-mcnt at 

 rarely with 2 hepatic ceca. Heart elongated. Male usually with charactcri-! ' 



the flagellum united with the base into one structure, long, taix-ring. with a row of hue ^pmulcs 

 toward apex; usually with grasping organ on first foot and copulatory organs on ixfet -abdomen. 



4 (5) Dorsal ramus of antenna 3-jointed, rostrum present. 



Sida Straus 1820. 



Head with large gland on dorsal side; pointed rostrum; no fomices. .\ntennulcs of 9 

 attached to side of rostrum, short, truncate, with short llagellum. Ventral ramus of antennae 

 2-jointed. Antennules of $ very long; no copulatory organ; first fcxjt with hook. 



Only one American species. . . Sida crystallina {0. V. 'SiiiUcr) i-j^s. 



■y^' 

 ^f^- 



A **^^^*tit^<ii£ii:j 



I MM. I ' 



Fig. 105 1. Sida crystallina. (Unless otherwise indicated all figures were dniwn i-sjiccLUl) for this 



chapter.) 

 Color yellowish-hyaline, sometimes with brilliant blue SF>ots. Ungth. 9. 3.0-4.0 mm 

 $ , 1.5-2.0 mm. 

 Common in lakes and ponds among weeds. 



5 (4) Dorsal ramus of antenna 2-jointed. 



6 (9) With lateral expansion on basal joint of dorsad ramus of antenna. 



Liitofhi Straus 1S20 . . 7 



Large, tongue-shaped projection on ventral side of head, 't^ventral surface coi^ca^. Vcnilral 

 ramus of antennae 3-Jointed. Long setae on posterior marpn of valves. h>c dorsal, far Irum 

 optic ganglion. $ with copulatory organ; no hook on lirbt toot. 



