321 



Antennae I have a three- segmented peduncle; the proximal segment of 

 the flagellum is long and conical. Antennae II of females are four- to 

 five-segmented. The mandibles have a strong cylindrical dentate pro- 

 cess and a palp is present in both sexes. In maxillae I the outer lobe 

 bears five terminal spinules. In the maxillipeds the inner lobes are well 

 262 developed and generally bear two terminal setae. The coxal plates are 

 free. The distal process of the 5th segment of pereopods I forming a 

 chela is weakly developed, but. in pereopods II is well developed and 

 spoon-shaped. Pereopods III-IV are longer than V-VII. 



Type species: Cancer medusarum O.F. Miiller, 1776. 



The genus includes seven species, some of which are very close and 

 difficult to distinguish. 



KEY TO SPECIES OF GENUS HYPERIA' 



1. Marginal and submarginal setae along posterior margin of 5th and 

 6th segments of pereopods III-IV unequal in length and may even' 

 be absent on 6th segment 2. 



— Setae along posterior margin of 5th and 6th segments of 

 pereopods III-IV equal in length, short 4. H. spinigera Bov. 



2. Outer lobes of maxillipeds oval, armed with short setae along entire 

 inner margin ' 3. 



— Outer lobes of maxillipeds sharply taper distally; long, strong spines 

 situated along their inner margin, replaced by short setae only in 

 proximal third 6. 



3. Coxal plate IV not acuminate, not protruding laterally. Distribution 

 not confined to the Antarctic 4. 



— Coxal plate IV acuminate, protruding laterally in adult individuals. 



Distribution confined to the Antarctic 



3. H. macrocephala (Dana). 



4. Endopodite of uropods III twice or more times longer than wide . . . 

 5. 



— Endopodite of uropods III less than twice longer than wide 



5. H. crassa Bowm. 



5. Posterior margin of 6th segment of pereopods I and II covered with 

 spines 2. H. medusarum (Miiller). 



— Posterior margin of 6th segment of pereopods I and II not covered 

 with spines \. H. galba (Mont.). 



' After the book had gone to press, we found a new species, Hyperia sp., close to 

 H. leptura, which Hves in large numbers on the jelly fish Chrysaora placamia in the 

 coastal 200-mile zone of northern Peru. (See addendum). 



