270 



222 In the pleon, somite III is the longest and the urosome is shorter 

 than it. The lateral notches marking the fused urosomites II and III are 

 very small. The geminate urosomite is approximately equal in length to 

 urosomite I and its posterior lateral angles are slightly stretched back- 

 ward and acute. The basipodites of the uropods are longer than the rami. 

 The rami of uropods I-II are coarsely denticulate along the margins. 

 The outer margin of the exopodite of uropods III is smooth, while both 

 margins of the endopodite and the inner, margin of the exopodite are 

 finely denticulate. Sexual dimorphism is distinctly expressed in the struc- 

 ture of uropods III: in males the endopodite is notably broader than 

 the exopodite, longer, and apically rounded. The telson is roundish- 

 triangular, not extending to the middle of the basipodite of uropods III. 



Distribution : Tropical waters of the Atlantic, Pacific and Indian 

 oceans; the species occurs everywhere is small numbers. 



223 10. Vibilia australis Stebbing, 1888 (Fig. 110) 



Stebbing, 1888: 1287; Vosseler, 1901: 124; Behning, 1912: 219; 

 Behning and Woltereck, 1912: 219 (pelagica var.); Behning, 1925: 488; 

 1927: 119; Pillai, 1966: 20S.—seriocellatus Stephensen, 1932: 9. 



Among all the known species of Vibilia this is the smallest. The 

 body of the adult crustacean rarely reaches more than 5 mm, on average 

 about 3 mm. 



The body is well proportioned. The head is small, not exceeding in 

 length the first two somites of the pereon, its height reducing towards the 

 anterior margin. The rostrum is small and triangular. The structure of the 

 eyes is specific: they are pale and consist of three vertical rows of indi- 

 vidual ocelli. Antennae I are notably longer than the head, being equal 

 to it and somite I of the pereon; the antennal base is massive — thicker 

 than the flagellum and 1/3 the length of the entire antennae; the flagellum 

 broaded slightly, tapers gently toward the apex, and is shifted toward the 

 straight lower margin; two apical rudimentary segments bearing short 

 setae are well noticeable. Antennae II are very short, not longer than the 

 base of antennae I, and consist of two to four short segments, of which 

 the distal segment is armed with short setae. The maxillipeds have a 

 low medial lobe whose distal margin is concave in the middle, distally 

 broadened outer lobes, have a rounded apex. 



The somites of the pereon are almost equal in size, somites I-II being 

 the shortest and V-VI the longest. The 2nd segment of pereopods I is 

 broadened and equal in length to the rest of the leg; the 6th segment 

 is oval, longer than the 5th segment; the claw is strong, curved, just 

 barely shorter than the 6th segment, and has a finely denticulate posterior 

 margin. The 2nd segment of pereopods II barely broadens, is slightly S- 



224 shaped, and hardly longer than the rest of the leg; the process of the 



