564 



of a broadened 2nd segment and usually one markedly reduced distal 

 segment. The basipodite of uropods I has a denticulate anterior margin; 

 the rami of uropods I-III are lanceolate; the endopodite of uropods II 

 and III is fused with the basipodite or is free. The telson is fused with 

 the last urosomite. 



Type species: Tetrathyrus forcipatus Claus, 1879. 



455 KEY TO SPECIES OF GENUS TETRATHYRUS 



1. Second segment of pereopods V not more than twice longer than 

 wide. Endopodite of uropods II and III fused with basipodite. Telson 



shorter than last urosomite 1 . T. forcipatus Claus. 



— Second segment of pereopods V 2.3-2.8 times longer than wide. 

 Endopodite of uropods II and III not fused with basipodite. Telson 

 longer than last urosomite 2. T. arafurae Stebb. 



1. Tetrathyrus forcipatus Claus, 1879 (Fig. 244) 



Claus, 1879b: 14; 1887: 40; Stebbing, 1888: 1484; Chevreux, 

 1900: 150; Spandl, 1924: 38; 1927: 240; Chevreux and Page, 

 1925: 422; Stephensen, 1925a: 224. — inscriptus Bovallius, 1887a: 

 47. — rectangularis Bovallius, 1887a: 47. — moncoeuri Stebbing, 1888: 

 1480. — sanctijosephi Shoemaker, 1925: 54. 



Length of adult specimens 3.5-4.5 mm. 



The head is laterally roundish-triangular, somewhat stretched anteri- 

 orly, and its length in the upper part approximately 2/3 that of the lower 



456 part; there are no differences between males and females in size and 

 shape of the head. The 2nd and 3rd segments of antennae II in males 

 aie equal in length, the 4th slightly shorter, and the 5th, 4/5 the length 

 of the 4th segment. 



The 2nd segment of pereopods I is shorter than the distal segments 

 and the anterior margin more bulged than the posterior; the 4th seg- 

 ment is broadened; the 5th segment is narrower and shorter; the 6th 

 segment is not longer than the 5th. The 2nd segment of pereopods II 

 is longer than the distal segments, its anterior margin concave, and the 

 posterior margin bulged; the distal segments are the same as in pere- 

 opods I. The 2nd segment of pereopods V is twice longer than wide, its 

 anterior margin bulged only in the middle part, the posterior uniformly 

 bulged over its entire length; the distal segments together are longer than 

 the 2nd segment or equal to it. The 2nd segment of pereopods VI has 

 a concave anterior margin and the posterior margin is almost straight 

 in the middle part; the distal segments are 1/3-1/2 the 2nd segment in 

 length; the 4th segment is linear, longer than the successive segments 

 together; the distal process of the 4th segment reaches 1/3-1/2 the 5th 



