345 



KEY TO SPECIES OF GENUS HYPEROCHE 



1. Posterior distal angle of epimerons II and III slightly stretched and 

 acute 2. 



— Posterior distal angle of epimerons II and III round or straight, may 

 be finely denticulate, but not acute 5. 



2. Anterior distal angle of 6th segment of pereopods I and II not 

 stretched above claw 3. 



— Anterior distal angle of 6th segment of pereopods I and II stretched 

 above claw 4. 



3. Posterior margin of 5th and 6th segments of pereopods III and IV 

 denticulate 1 . H. medusarum (Kroyer). 



— Posterior margin of 5th and 6th segments of pereopods III and FV 

 armed with setae but not denticulate 7. H. luetkenides Walker. 



4. Distai process of 6th segment spoon-shaped, slightly curved, lower 

 distal angle of 4th segment not stretched 5. H. picta Bov. 



— Distal process of 6th segment of pereopods I and II almost straight, 

 lower distal angle of 4th segment stretched into narrow triangular 

 lobe 6. H. capucinus Barn. 



5. Lower distal angle of 4th segment of pereopods I stretched into long 

 process reaching almost to base of distal process of 5th segment . . 

 6. 



— Lower distal angle of pereopods I bears very short process 



4. H. martinezi (Muller). 



6. Claw of pereopods II free, not retractile into body of 6th segment. 



Posterior distal angle of epimerons II and III round 



2. H. mediterranea Senna. 



283 — Claw of pereopods II retractile. Posterior distal angle of epimerons II 

 and III acute 2>. H. cryptodactylus Stebb. 



1. Hyperoche medusarum (Kroyer, 1838) (Fig. 142) 



Kroyer, 1838: 288 (Metoecus); Hansen, 1888: 58; Pirlot, 1929: 118; 

 Hurley, 1955: 144 — abyssorum Boeck, 1870: 6 {Metoecus) — medusarum, 

 abyssorum Boeck, 1872: 82 (Tauria) — kroeyeri, tauriformis, prehensilis, 

 abyssorum, luetkeni Bovallius, 1889: 87-97 — kroeyeri Sars, 1895: 9; 

 Chevreux and Page, 1925: 405 



Maximum length of sexually mature individuals from the Arctic seas 

 up to 15 mm (female) but generally does not exceed 5-6 mm. 



Male: The body is elongated. The integument is thick and smooth, 

 as if polished. The length of the head is equal to the length of the first 

 two somites of the pereon. The eyes occupy the entire surface of the 

 head. 



The flagellum of antennae I is barely shorter than the body and 

 longer than the flagellum of antennae II; its oval-conical 1st segment is 



