344 



pereopods V and VI it slightly tapers or broadens distally, its length 

 twice its width; the 5th segment of pereopods V and VI is the same 

 length as the 3rd and 4th together, of pereopods VII somewhat shorter; 

 the 6th segment of pereopods V and VI is somewhat shorter than the 

 5th, of pereopods VII approximately the same length; the claw is 1/5 the 

 length of the 6th segment. 



The margins of the basipodite of uropods I are finely denticulate; 

 the rami are narrowly lanceolate, approximately equal in length, but 

 the exopodite shorter than the endopodite. The basipodite and rami of 

 uropods II are shorter than in uropods I. The margins of the basipodite of 

 uropods III are finely denticulate and the rami lanceolate, almost equal 

 in length, and less than half the length of the basipodite. Setae are absent 

 on the surface of the uropods. The telson is triangular, with a round apex, 

 its length equal to it width at the base; it may be shorter or somewhat 

 longer than half the length of the basipodite of uropods III. 



Distribution: A surfacial, warm-water species known from the trop- 

 282 ical regions of the Pacific (central and equatorial regions, the Gulf of 

 Panama) and Atlantic (Bermudas) oceans. 



4. Genus Hyperoche Bovallius, 1887 



Bovallius, 1887a: 18; 1889: 83; Stebbing, 1888: 1398. 



Crustaceans of medium size, 4-15 nrmi. 



The body is similar in shape to Hyperia. All the somites of the 

 pereon are free. The head is large and semicircular. The eyes occupy 

 the entire lateral surface of the head and are dorsally contiguous. The 

 interantennal lobe is not developed. Antennae I have a three-segmented 

 peduncle, in females longer than antennae II; antennae II in females are 

 four-segmented. The mandibles have a strong dentate process and a three- 

 segmented palp in both sexes. Maxillae I have a very broad leaflike palp. 

 The maxillipeds have large well-developed inner lobes. 



The coxal plates are free. Pereopods I and II have a chela formed 

 by the 6th segment and distal process of the 5th segment; in pereopods I 

 and II the process of the 5th segment is laterally compressed, knife- 

 shaped, and denticulate along the anterior margin. Pereopods V-VII are 

 approximately equal in length. 



Type species : Metoecus medusarum Kroyer, 1838. 



The genus is close to Hyperia but readily distinguished from it by 

 the shape of the process of the 5th segment of pereopods I and II. 



Most of the species are rare and known from just a few specimens. 

 Therefore, the systematics of the genus is not well worked out. 



At present the genus includes seven species but the validity of some 

 requires verification. 



