545 



— Distal process of 5th segment of pereopods I and II with denticu- 

 late margins; posterior margin of 6th segment without tooth. Pere- 

 opods VI six-segmented. Telson fused with last urosomite 3. 



3. Height of head much less than width. Third segment of pereopods V 

 articulated with 2nd subterminally. Pereopods VI consist of a broad- 

 ened 2nd segment and one-two distal segments 



1 . Platyscelus Bate. 



— Height of head equal to width. Third segment of pereopods V artic- 

 ulated with distal margin of 2nd segment. Pereopods VII consist of 

 only broadened 2nd segment 2. Hemityphis Claus. 



4. Second segment of pereopods I broadened distally. Sixth segment 

 of pereopods I and II with deep notch on distal end; 5th segment 

 without distal process. Pereopods VI seven-segmented 



. , 4. Tetrdthyrus Claus. 



— Second segment of pereopods I almost linear. Sixth segment of pere- 

 opods I and II without notch on distal end; 5th segment with distal 

 process. Pereopods VI six-segmented 3. Paratyphis Claus. 



1. Genus Platyscelus Bate, 1861 



Bate, 1861: 4; 1862: 329; Chevreux and Page, 1925: 419; Stephensen 

 1925a: 213; Bowman and gruner, 1973: 55.— Typhis Risso, 1816: 

 Xll.—Eutyphis Claus, 1879b: 150; 1887: 31.— Eutyphes Bovallius, 

 1887a: 45. 



The head is high and broad, ventrally passes into a beakshaped pro- 

 cess, and is smoothly rounded anteriorly. Each of the two distal segments 

 of antennae II in males is shorter than half the length of the preceding. 



Pereopods I and II have chelae; the distal process of the 5th seg- 

 ment constitutes the immovable part of the chela and both margins are 

 denticulate; the posterior margin of the 6th segment is denticulate. The 

 3rd segment of pereopods V is articulated subterminally with the inner 

 surface of the 2nd segment. The 2nd segment of pereopods VI is not less 

 than three times longer than the rest of the segments together; the distal 

 segments are articulated with the 2nd segment at some distance from its 

 440 distal margin,' and of these the 4th segment is the largest; the anterior 

 margin of the 4th and 5th segments is denticulate; the 6th segment is 

 thin, virgate, sometimes clawlike; the claw is absent or barely noticeable; 

 the groove for the telson is almost straight. Pereopods VII consist of a 

 broadened 2nd segment and one-two distal segments; the length of the 

 apical segment may vary considerably. 



The outer margin of the basipodite of uropods I is denticulate and 

 the rami are pointed. The basipodite of uropods II is much shorter than 

 the rami and the margins are smooth for the most part. Uropods III are 

 the shortest; the basipodite is fused with the endopodite; the exopodite 



