583 



to the base of the segment; the 3rd-7th segments together are 1/4 the 

 length of the 2nd; the 4th segment is straight and linear and without 

 an anterior distal process; the 5th segment is straight, almost linear, and 

 2/3 the 4th in length and narrower than it; the 6th segment is 1/2 the 

 length of the 4th; the claw is approximately 1/3 the length of the 6th 

 segment. The 2nd segment of pereopods VII is 2.5 times longer than 

 wide, the anterior margin concave, and the posterior convex; the number 

 and length of the distal segments are highly variable but individuals with 

 two short distal segments encountered more often. 



The basipodite of uropods I is distally broadened and its anterior 

 margin denticulate almost throughout its length; the exopodite is lance- 

 olate and equal to the basipodite in length; the endopodite is broadly 

 lanceolate, 1/3 the exopodite in length and twice as broad, and its tip 

 does not reach the tip of the telson. The basipodite of uropods II is dis- 

 tally broadened; the rami are lanceolate; the exopodite is 1.5 times longer 

 than the basipodite; and the endopodite is 1.5 times or more longer than 

 the exopodite. The basipodite of uropods III is almost equal in length 

 and width; the rami are broadly lanceolate; the endopodite is almost 2.5 

 times longer and also broader than the exopodite, its tip reaching some- 

 what beyond the tip of the telson. The last urosomite has slightly bulged 

 lateral margins and its maximum width is almost twice its length. The 

 telson is hemispherical, its length half its width at the base. 



Distribution: This species is widespread in the tropical zone of all 

 oceans. It is known from the Atlantic (between 47° N and 36° S, includ- 

 ing the equatorial zone), Indian (Arabian Sea), and Pacific (Kuroshio, 

 Hawaiian Islands, eastern part from 40° N to 30° S, equatorial zone) 

 oceans. It inhabits the upper 200 m layer. 



4. Genus Parascelus Claus, 1879 



Glaus, 1879b: 18; 1887: 45; Stebbing, 1888: 1496; Spandl, 1924: 

 42; Stephensen, 1925a: 208; Ghevreux and Page, 1925: 423; Hurley, 

 1955: 183. 



This genus is very close to the genus Thyropus, a fact noted by many 

 investigators, in particular Hurley (1955). He considered that the status 

 of the genus Parascelus raises definite doubts and that there are serious 

 premises for relegating it to a synonym of the genus Thyropus. These 

 considerations notwithstanding, there are certain significant morpholog- 

 ical features that dictate the isolation of group of species in a separate 

 genus. 



The basic differences between Parascelus and Thyropus are given 

 as follows: 



