548 



pereopods V is narrowed in the distal part and much longer than the 

 distal segments together; the 5th and 6th segments have a denticulate 

 anterior margin although denticulation often does not occur throughout 

 its length. The 2nd segment of pereopods VI is the largest, the anterior 

 margin is concave, and the distal segments together equal to 1/3 its 

 length; the 4th and 5th segments have a characteristic pecten along the 

 anterior margin; the distal process of the 5th segment is weak or absent; 

 the 6th segment is half as narrow as the 5th and virgate; the claw is 

 generally absent. The 2nd segment of pereopods VII is curved like a 

 boomerang; one or two distal segments may be present, in which case 

 the length of the apical segment may vary strongly. 



The basipodite of uropods II is short, its width almost equal to its 

 length; the margins of the exopodite are smooth; the endopodite is much 

 longer than the exopodite. The endopodite of uropods III has denticulate 

 margins, is almost twice broader and longer than the exopodite, and its 

 tip extends slightly beyond the tip of the telson. 



Distribution: Generally circumtropical. It is found in the 

 Mediterranean Sea, the Atlantic (south of 50° N), Indian (eastern part), 

 and Pacific (Kuroshio, central waters, equatorial zone, region of New 

 Zealand) oceans. It inhabits mostly the upper 2(X) m layer but is 

 sometimes found deeper, particularly in the Mediterranean Sea, where it 

 has been recovered to a depth of 800 m. 



442 2. Platyscelus armatus (Claus, 1879) (Fig. 236) 



Claus, 1879b: 10 {Eutyphis); 1887: 36 (Eutyphis); Bovallius, 1887a: 

 45 (Eutyphes); Stebbing, 1888: 1464; Spandl, 1927: 229.— inermis Cl&us, 

 1887: 37 (Eutyphis). 



Length of sexually mature specimens 12-16 mm. 



The head is approximately 2.5 times higher than long, its width 

 four times its length. The flagellum of antennae I in males consists of 

 a broad basal segment (the lower surface of which is densely pubescent 

 with long hairs while the segment itself is bent upward) and three dis- 

 tal segments, of which the first is also rather densely pubescent in the 

 distal part. Antennae II in males is folded zigzag four times; moreover, 

 the two distal segments are almost 1/4 the length of the two proximal 

 segments. 



All somites of the pereon and the pleon bulge from the dorsal side. 

 Coxal plates V and VI are longer than the rest; coxal plates V have a 

 pointed lateral process whereby P. armatus can be readily distinguished 

 from other species of the genus. 



The 2nd segment of pereopods I has a bulged anterior margin 

 bearing rather sparse setae and an almost straight posterior margin; the 

 5th segment without the distal process is longer than its width (in the 

 other species of the genus, vice versa); the distal process is broader than 



