10 



U.S. NATIONAL MUSEUM BULLETIN 2 36 



apical spine of the 3rd exopodal segment of legs 1-4 to the internal 

 margin, we come to uniform setal formulae for all species. Leg 5 

 differently developed in the various members of the genus; exopodite 

 always 3-segmented, endopodite 1- to 3-segmented. Setal formula: 



endopodite exopodite 



leg 1 1.2.321 1.1.322 



leg 2 1.2.422 1.1.422 



leg 3 1.2.422 1.1.423 



leg 4 1.2.322 1.1.423 



leg 5 (modified) 0-1.1.0-413 



Males. — Only shghtly dlfiering from females in general form of 

 body. Kostrum more slender, at times movable at base. Abdomen 

 5-segmented; genital aperture at left side of 1st abdominal somite; 

 anal somite as small as in female and nearly fused to fm-cal rami. 

 Left antennule as in female, number of aesthetascs on basal segment 

 increased. Right antennule modified to form graspmg antennule, 

 movable part formed by 3 or 4 segments. Oral parts not reduced. 

 Legs 1-4 as in female. Leg 5 strongly modified, chelate; coxae large, 

 swollen, both sides sometunes fused. Left basis fused to coxa, right 

 basis free. Exopodites strongly deformed; endopodites present as 

 blade-shaped appendages, that of right side usually fused with basis. 



Type species: Pseudocyclops crassiremis Brady, 1872. 



The following species of Psevdocyclops are known : 



Females 

 P. crassiremis Brady, 1872 

 P. obtusatus Brady and Robertson, 



1873 

 P. umbricatus Giesbrecht, 1893 

 P. magnus Esterly, 1911 

 P. Mens Gurney, 1927 



P. simplex Scwell, 1932 



P. australis Nicholls, 1944 



P. reductus Nicholls, 1944a 



P. gohari Noodt, 1958 



P. cokeri Bowman and Gonzdlez, 1961 



P. paulus Bowman and Gonzalez, 1961 



P, rostratus Bowman and Gonzdlez, 



1961 

 P. rubrocinctus Bowman and Gonzdlez, 



1961 



Males 

 P. crassiremis Brady, 1872 

 P. obtusatus Brady and Robertson, 



1873 

 P. umbricatus Giesbrecht, 1893 



P. latisetosv^ Sewell, 1932 

 P. simplex Sewell, 1932 



P. gohari Noodt, 1958 

 P. cokeri Bowman and Gonzdlez, 1961 

 P. paulus Bowman and Gonzdlez, 1961 

 P. rostratus Bowman and Gonzdlez,' 



1961 

 P. rubrocinctus Bowman and Gonzdlez, 



1961 



A new species will be described below as: 



P. paciUcus, new species 



The various species can be distinguished best by peculiarities of 

 the 5th legs. The following keys, which may serve to distinguish 



