563 



the 5th segment is sHghtly longer than the 4th but equal to it in width, 

 its rounded distal process 1/5 the length of the 6th segment, its anterior 

 margin armed with two, the posterior with five-six setae; moreover, the 

 distal part of the 5th segment is armed with very fine spinules; the 6th 

 segment is narrowed distally, with straight margins, the posterior margin 

 armed medially with very fine spinules, and the segment additionally 

 with several longer lateral spines; the claw is longer than in pereopods I. 

 The 2nd segment of pereopods V is oval, twice longer than wide, its 

 anterior margin undulating in the middle part and armed with a few 

 setae in the distal part, and a notch occurs at its tip into which the 3rd 

 segment fits; the 3rd-7th segments together are much shorter than the 

 2nd segment, and of these the 6th is the longest. The 2nd segment of 

 pereopods VI is the same as in P. parvus but lacks a shallow notch on 

 the anterior and posterior margins; the 4th and 5th segments are narrower 

 than in P. parvus and P. maculatus; in the 4th segment the anterior distal 

 process extends slightly beyond the middle of the 5th segment; the 6th 

 segment is clawlike, half the length of the 5th segment. Pereopods VII 

 vary markedly in structure; they may have just one strongly extended 

 and narrow basal segment or, in addition, two-three rudimentary distal 

 segments. 



The uropods and telson are the same as in P. maculatus. 



Distribution: Known from the Atlantic (Cape of Good Hope, 35° N, 

 7° W) and Pacific (southeastern part) oceans and the Red Sea. 



4. Genus Tetrathyrus Claus, 1879 



Glaus, 1879b: 14; 1887: 31; Stebbing, 1888: 1481; Stephensen, 1925a: 

 224; Chevreux and Page, 1925: 422; Spandl, 1927: 240. 



Small animals, not more than 5 mm in length. 



The basal segment of the flagellum of antennae I in males 

 is markedly curved forward and somewhat longer than the three 

 distal segments together. Antennae II in males are folded zigzag five 

 times and the last two segments only slightly shorter than the two 

 preceding ones. 



Pereopods I and II are identical in structure: in pereopods I the 2nd 

 segment is distally broadened and has a notably bulged anterior margin; 

 of the distal segments, the 4th is the broadest; the 6th segment has a 

 notch at the tip, such that together with the claw it forms a chela like 

 structure. The 2nd segment of pereopods V has a bulged posterior margin 

 and a straighter anterior margin; the 3rd segment is articulated with the 

 2nd segment subterminally. The 2nd segment of pereopods VI has a 

 curved anterior margin; the 4th segment has a distal process; the 6th 

 segment is normal, not modified into a claw; the anterior margins of the 

 4th-6th segments is denticulate; the claw is short. Pereopods VII consist 



