245 



the length of the 6th segment, with a highly denticulate posterior margin. 

 Pereopods III-IV are similar in length; the 4th segment is slightly longer 

 than the 5th segment and is not bulged; the 6th segment is longer than 

 the 5th and highly denticulate posteriorly; the claw is curved, less than 

 1/3 the length of the 6th segment, and has a few teeth on the posterior 

 margin. Pereopods V-VI are almost equal in length; the 2nd segment is 

 quite broad and oval; the 4th segment is smooth, somewhat longer than 

 the 5th; the 5th segment is shorter than the 6th and both segments have 

 a finely denticulate anterior margin; the claw is very short, less than 1/4 

 the length of the 6th segment. Pereopods VII are relatively long (ratio of 

 their length to that of pereopods VI, 7 : 9); the 2nd segment is broadly 

 oval, its length slightly more than width; the finger-shaped 7th segment 

 is approximately the same length as the preceding one or slightly shorter. 

 203 The pleon is longer than the last four somites of the pereon. The rami 



of the pleopods comprise 12-13 segments. Urosomite I is longer than the 

 fused urosomites II and III, urosomite II being the shortest. The posterior 

 angles of the last urosomite are round and not stretched backward. The 

 basipodite of the uropods is much longer than the rami and has parallel 

 margins. The basipodite of uropods I is finely denticulate from the outer 

 side. The rami of all uropods are equal in length and in uropods I-II 

 are finely denticulate on both sides. The exopodite of uropods III is 

 smooth from the outer side. The telson is broad, semicircular, of the 

 same length as urosomite III and extends to the middle of the basipodite 

 of uropods III. Sexual dimorphism is hardly expressed in the structure 

 of this pair of uropods. 



Notes: The species is closest to V. propinqua but is distinguished 

 by the short claws of pereopods V-VI, absence of distinct sexual dimor- 

 phism in the structure of uropods III and by a round telson. 



Distribution: The species was described from the Mediterranean Sea 

 and is mainly found in the Atlantic Ocean; it has been detected in the 

 Indian Ocean also, northeast of Madagascar. 



2. Vibilia viatrix Bovallius, 1887 (Fig. 102) 



Bovallius, 1887a: 8; 1887b; 63; Behning, 1925: 482; Stephensen, 

 1918: 41.— viator Stebbing, 1888: 1286. hirondellei Chevreux, 1900: 

 126.— dentata Chevreux, 1900: 129.— califomica Holmes, 1908: 490. 



Length of sexually mature adults up to 8.1 mm. 

 205 The body is well proportioned. The head has a small triangular 



rostrum; the frontal part of the head in females converges gently towards 

 the base of antennae I; in males this part of the head is more convex. 

 The eyes are average in size but in males larger and tapering downward. 

 The 1st segment of the base of antennae I is approximately the same 

 length as the 2nd and 3rd together; the flat 1st segment of the flagellum 

 in females is slightly longer than the head, in males is equal to the head 



