THE WATER FLEAS (CLADOCERA) 



Antcn- 



114(109) Head much depressed; rostrum close to margin of valves, 

 nules slender, not enlarged near distal end. 



Macrotltrix borysthcnica Malilc 1890 



Dorsal marKin of heafi evenly roun<ic*l o\<r int.. »V...f • 

 valves without sinus. Front of lu-a<l rem r -.^ 



trum is very close to valves. Antennule^ . xl 



tered tine hairs; olfactory setae small. e<jual ; . .wjcn 



elongated, bilobed; with numerous fjne spinulcn an<l hain 

 on both lobes. Claws .small. Kye m«»<lcratc; o<rllu» at 

 rostrum. Color transparent Length. 9. '" « « mm. 



Albuquerque, New Mexico (Herrick; 



Fig. 



Macrothrix horystheniiii. (.\fter Matile.) 



115 (108) Dorsal margin of head curved abruptly in front of eye. .Antennuk-s 

 slender Macrothrix rosea (Jurinc) i8io. 



Form broadly ovate. Valves reticulated, crested, not serrate. Head large; its (lorsal mar- 

 gin rounding over abruptly into anterior margin. Antennulcs long, slender, not enlarRnl near 

 apex; lateral sense-hair near base on small elevation; olfactor\' setae une(|ual. ro>t-aU)iimm 

 extended into blunt process, on which abdominal setae are borne; pre-anal jurt >*-mi clli(»tical. 

 with numerous spinules along convex edge and many fine hairs: anal jKirt with st- veral sfnall 

 spines. Claws small, smooth. Summer eggs numerous; ephippium well <level()|)e<l. with ; ciar»- 

 Antennules of $ long, curved. Post-abdomen terminating in long, lleshy pri>jtvti<>n oq 

 which the vasa deferentia open. Hook of first foot serrate at tip Color tran>i»rrnl to 

 yellowish or sometimes a ruddy tinge. Length, 9. ca. 0.7 mm.; $, 0.4 mm. Common 

 everywhere in marshy pools and margins of lakes. 



M. tenuicornis Kurz is a variety of this species All ^ $ found in .\merica a^rcc with M. 

 elegans Sars. 



0.1 MM I 



Fig. 1 1 16. Macrothrix rosea. 



