581 



the peduncle, and their tips extend beyond the tip of the telson. The 

 basipodite of uropods II is very short and fused with the endopodite or 

 indistinctly separated; the endopodite is lanceolate, very large, its tip 

 almost reaching the tip of the telson; the exopodite is shorter and twice 

 narrower than the endopodite. Uropods III are somewhat longer than the 

 telson and the exopodite 2/3 the length of the endopodite. The tip of the 

 telson is smoothly rounded, its length less than the width at the base and 

 less than the length of the last urosomite. 



Distribution: Known from the Atlantic (43° N to 14° S), Pacific 

 (region of the Philippines), and Indian oceans, and the Mediterranean 

 Sea. It inhabits the upper 200 m layer. 



3. Genus Thyropus Dana, 1852 



Dana, 1852: 1008; Stebbing, 1888: 1452; Spandl, 1927: 25S.—Tanysce- 

 lus Claus, 1879b: 17; 1887: 45. 



The head is flattened anteriorly, its length in the lower part more 

 than in the upper. The pereon is broad and markedly bulged; somites I 

 and II are ohort. The urosome and telson are tucked under the belly. 



Pereopods I and II are simple; the 5th segment has no distal process. 

 The 2nd segment of pereopods V is oval; in pereopods VI this segment 

 is strongly stretched distally and much larger. Pereopods VI have a full 

 complement of segments; the 4th segment has no distal process. Pere- 

 opods VII are short and weak; the number of distal segments varies from 

 two to five. 



The endopodites of uropods II and III are free. The telson is hemi- 

 spherical. 



Type species: Thyropus diaphanus Dana, 1852. 



469 1. Thyropus sphaeroma (Claus, 1879) (Fig. 253) 



Claus, 1879b: 17 (Tanyscelus); 1887: 45 {Tanyscelus)—Boval\ms, 

 1887a: 43; Stebbing, 1888: 1496; Spandl, 1927: 259.— diaphanus Dana, 

 1852: \0\3. —atlanticus Bovallius, 1887a: 43.— danae Stebbing, 1888: 

 1492. 



Length of adult individuals up to 7 mm. 



Antennae I in males with a four-segmented flagellum; the 1st seg- 

 ment is the largest, notably curved forward, and distally so narrows that 

 its apical margin is equal in width to the base of the 2nd segment. 

 Antennae II in males with a short, uncurved basal segment, with slightly 

 bulged margins, its width 1/3 its length; the antennae are long and thin 

 and folded zigzag five times; the 2nd segment is approximately four 

 times longer than the basal; the 4th segment is much shorter than the 

 3rd and almost twice as long as the 5th. 



