44 



Pereopods I and II are simple, or with a chela formed, usually, by the 

 6th article and projection of the 5th; the 2nd article of pereopods V-VII is 

 40 sometimes remarkably enlarged, forming a "roof (operculum) over the 

 brood chamber. Pereopods VII are sometimes reduced, comprising only 

 two to three articles. The gills are located on pereopods II-VI, rarely 

 on pereopods FV-VI. Pereopods II-V have oostegites. The urosoma is 

 stout, its last somites often fused. The uropods are weakly armed; the 

 endopodites form several groups and are fused with the peduncle; the 

 exopodite of uropods III is always one-segmented. The oral appendages, 

 ambulatory legs, and uropods are usually weakly armed. The spines and 

 setae are usually short, always not plumose. The telson is always entire. 

 Reduction of several internal organs is also characteristic of hyperiideans. 

 The hepatopancreatic caeca are greatly reduced or totally absent; rectal 

 glands are absent. 



The suborder is divided into two infraorders, Physosomata and 

 Physocephalata, comprising 7 and 16 families respectively, which in 

 turn are grouped into 7 superfamilies. 



KEY TO INFRAORDERS, SUPERFAMILIES, 

 AND FAMILIES OF SUBORDER HYPERIIDEA* 



1. Head usually short, not longer than somite I of pereon. Eyes always 

 small, aberrant or absent. Antennae I always with strong conical prox- 

 imal segment of flagellum and usually with three very small distal 

 segments (their number rarely reduced to two or quite disappearing 

 in adults). Mandibles without dental process. Maxillae I with an inner 

 lobe. Infraorder Physosomata 2. 



— Head usually longer than somite I of pereon. Eyes large, occupying 

 large part of surface of head, may be small, or even absent; in the 

 latter case, flagellum of antennae II in male whiplike or proximal seg- 

 ment of flagellum of antennae I oval and inner lobes of maxillipeds 

 fused. Proximal segment of flagellum of antennae I not conical or 

 number of distal segments more than three. Mandibles usually with 

 dental process. Maxillae I without inner lobe, or lobe retained as a 

 small bare process. Infraorder Physocephalata 8. 



2. Antennae I narrowly conical, stout, long, often slightly shorter or 

 longer than pereon. Mandibles with narrow cutting margin, with- 

 out palp, or with only its one-segmented rudiment. Superfamily Sci- 

 noidea 6. 



— Antennae I conical, not exceeding length of the first three-four pere- 

 onal somites. Cutting edge of mandibles may be broad or narrow, 

 but in latter case mandibular palp always presents 3. 



* Key has been changed slightly from Russian text by authors — Eds. 



