248 



5 th segment of pereopods VI; the maximum width of the 2nd segment is 

 slightly less than its length and the round lobe of the posterior margin is 

 weakly stretched downward to the end of the 3rd segment; the anterior 

 margin of the 2nd-4th segments bears one distal spinule, the 4th segment 

 having a similar spinule in the distal part of its posterior margin; the 5th 

 segment is equal to the 4th in length, while the 6th segment is slightly 

 longer; the distal margin of the 5th segment is finely denticulate; the 7th 

 segment has an indistinct alveolate pattern throughout its surface. 



The rami of the pleopods are 10- to 12-segmented. 



The fusion of urosomites II and III is laterally demarcated by a shal- 

 low notch. Urosomite I is the longest and equal in length to urosomites II 

 and III together, and urosomite II is the shortest. The lateral angles of 

 the last urosomite are not stretched posteriorly. The uropods are simi- 

 lar in males and females. The rami are shorter than the basipodites. the 

 206 basipodite of uropods I is finely denticulate along the distal part of the 

 inner margin and coarsely denticulate in the distal half of the outer mar- 

 gin; the rami are very coarsely denticulate and their ends extend to the 

 end of uropods III. Uropods II are shorter, with a smooth basipodite; the 

 ends of the rami extend slightly beyond the basipodite of uropods III; 

 both margins of the endopodite and the inner margin of the exopodite 

 are denticulate, while the outer margin of the exopodite is denticulate 

 only distally. The basipodite of uropods III is smooth; the rami in both 

 sexes are similar in length and apically acuminate; both margins of the 

 endopodite and the inner margin of the exopodite are finely and uni- 

 formly denticulate; the outer margin of the exopodite is smooth, with 

 several sensillae. The telson is roundish-triangular, almost equilateral. 



Notes: V. dentata Chevreux, 1901 was described from one young 

 female and undoubtedly belongs to the present species; the shape of 

 ant( nnae I, the long process of the 5th segment of pereopods II, the 

 bulged 4th segment of pereopods III-IV, long claws as well as the struc- 

 ture of the urosome confirm the identical nature of these forms. The 

 basic distinguishing feature of V. dentata is the relatively large denticles 

 on the posterior margin of the 6th segment of pereopods I, a feature 

 characteristic of V. viatrix as well. 



Distribution: Very widely distributed in the surface waters of three 

 oceans from 50° N to 50° S, but is more abundant in warm waters. 



3. Vibilia stebbingi Behning and Woltereck, 1912 (Fig. 103) 



Behning and Woltereck, 1912: 5; Behning, 1912: 213; 1925: 482. 

 Small species, in which adults reach only 5.5 mm. The body is well 

 proportioned, with a thin integument. The head is equal in length and 

 height. The eyes of females are small but in males large (occupying 1/5 

 and 1/2 of the lateral surface of the head respectively). Antennae I are 

 longer than the head and first two somites of the pereon; the 1st segment 



