12 U.S. NATIONAL MUSEUM BULLETIN 23 6 



9. Setae at 3rd endopodal segment of leg 5 strongly reduced: there are 2 almost 

 fully reduced setae at internal margin and 1 at apex. Several rows of 

 spinules on 2nd and 3rd segments. No spinuous process at external 

 margin of 1st endopodal segment of leg 5 and no club-shaped appendage 

 on 2nd exopodal segment of leg 1 . . .P. obtusatus Brady and Robertson 

 3rd endopodal segment of leg 5 with 4 setae: 2 at internal margin, 2 at 

 apex 10 



10. 4th abdominal somite with a pair of big spines at dorsal part of distal border, 



covering 5th abdominal somite. No spinuous process at external margin 

 of 1st endopodal segment of leg 5; 2nd exopodal segment of leg 1 without 

 club-shaped process beneath spine at external margin . . P. gohari Noodt 

 4th abdominal somite with smooth border. There is a strong spinuous process 

 at external margin of 1st endopodal segment of leg 5; 2nd exopodal seg- 

 ment of leg 1 with club-shaped process beneath spine at external margin 



P. aiistralis NichoUs 



11. All segments of endopodite of leg 5 fused, forming a curiously shaped endop- 



odite with 2 external spines (representing external spines of segments 

 1 and 2), 2 apical spines flanking a small seta, and 2 almost apical internal 

 spines. About 5 rows of teeth on endopodite . . P. crassiremis Brady 

 1st and 2nd endopodal segments of leg 5 fused, segment 3 free. Fused 

 lst-2nd segments on each side produced into a spine; segment 3 with 

 strong apical spine and 1 seta 12 



12. Large species ( 9 1.1 mm.), thoracic somites 4 and 5 separate. 



P. magnus Esterly 



Small species ( 9 0.63 mm.) , thoracic somites 4 and 5 fused. Rami of f urea 



internally produced, overlapping P. latens Gurney 



MALES 



1. Left endopodite of leg 5 with 4-5 setae with swollen, nude base and plumose, 



slender apical part 2 



Left endopodite of leg 5 with some small setae or teeth 6 



2. Abdominal somites or anal operculum armed with big, strong teeth ... 3 

 Abdominal somites with smooth distal borders or with fine teeth; anal 



operculum unarmed 4 



3. Abdominal somites 2 to 4 distally armed with big, strong spines, particu- 



larly well developed on 4th somite. Furcal setae 2 and 3 on each 

 side strongly swollen, sausage-shaped, strongly plumose. 



P. gohari Noodt 

 Abdominal somites unarmed, but anal operculum with strong, flat spines. 

 Setae 2 and 3 of furca thick, with strong, basal marginal spines. 



P. pacificus, new species 



4. Head and 1st thoracic somite fused; left endopodite of leg 5 with 4 setae. 



P. cokeri Bowman and Gonzdlez 



Head and 1st thoracic somite separate; left endopodite of , leg 5 with 



5 setae 5 



5. Very small species (cf 0.37-0.43 mm.); right antennule 14-segmented. 



Setae of left endopodite placed along distal margin; spine at external 

 margin of left 1st exopodal segment linear, without serrate lamella. 



P. paulus Bowman and Gonzdlez 



Bigger species (cf 0.50 mm.); right antennule 17-segmented. Setae of left 



endopodite with the following distribution: 1 internal, 3 apical, and 1 



