110 U.S. NIATIONAL MUSiETJM BULLETIN 271 



3. Article 4 of pereopods 1-2 enormously elongate relative to other articles and 



often inflated (fig. 33/) 4 



Article 4 of pereopods 1-2 of normal length relative to other articles ... 5 



4. Palp of maxilla 1 claviform, slightly geniculate (figs. 33a, 6.). 



HYPERIOPSIDAE (p. 261) 



Palp of maxilla 1 not geniculate . proceed to couplet 5 



5. Gnathopod 2 with form of typical lysianassid mitten (fig. 3) b 



Gnathopod 2 not typical of lysianassids 7 



6. Accessory flagellum absent and pleonites 1-3 with sharp dorsal processes, 



articles 5 and 6 of gnathopod 2 lacking scales or minute coarse setules. 



(exceptional) acanthonotozomatidae (p. 117) 



If accessory flagellum absent then pleonites 1-3 dorsally smooth; accessory 



flagellum otherwise present, articles 5 and 6 of gnathopod 2 bearing scales 



or minute coarse setules (fig. 3) lysianassidae (p. 294) 



7. Urosomites all coalesced 8 



Urosomites separate 9 



8. Uropod 3 biramous (fig. 22) prophliantidae (p. 432) 



Uropod 3 uniramous (fig. 13) kuriidae (p. 280) 



9. Uropod 3 formed only of small, scale-like peduncle. 



Didymocheila (incertae sedis) (p. 478) 

 Uropod 3 bearing one or two rami (inner often reduced) 10 



10. Uropod 3 with one ramus Microprotopus (Isaeidae) (p. 274) 



Uropod 3 with two rami 11 



11. All mouthparts except maxilliped replaced by ventral buccal keel and bulbs. 



(fig. 20) anamixidae (p. 145) 

 Mandibles, lower lip and maxillae present 12 



12. Accessory flagellum 1-2 articulate or absent, mouthparts from lateral view 



usually grouped in conical bundle, pereopods not strongly spinose . . 13 



Accessory flagellum always 1 + -articulate, mouthparts from lateral view 



usually quadrately grouped, pereopods strongly spinose and setose ("fos- 



sorial") (fig. 45) (exceptional) haustoriidae (p. 248) 



13. Mandibular palp present, pleon processiferous (fig. 7). 



(exceptional) acanthonotozomatidae (p. 117) 

 Mandibular palp absent, pleon never processiferous (fig. 4) . 



STEGOCEPHALIDAE (p. 436) 



SECTION C 



1. Body plan cylindrical or depressed (tanaid-like, caprellid-like or extremely 



broad and flat) 2 



Body plan compressed laterally (normal gammaridean plan) 6 



2. Mandible lacking palp and molar degraded 3 



Mandible with palp of one to three articles, molar triturative 4 



3. Body cylindrical, tanaid-like, smooth (fig. 8), coxae very small. 



coLOMASTiGiDAE and EOPHLiANTiDAE (pp. 182 and 209) 



Body strongly depressed, very broad and rugose (fig. 10), coxae large and 



splayed or body, if not rugose, with pereonites laterally discontiguous. 



PHLIANTIDAE (p. 405) 



4. Urosomites 1-3 coalesced 5 



Urosomites 2-3 coalesced and urosomite 1 very elongate (fig. 52). 



PODOCERIDAE (p. 426) 



5. Uropods 1-2 of very diverse structure (fig. 53) . . . cheluridae (p. 180) 

 Uropods 1-2 similar to each other and of normal gammaridean structure. 



(exceptional) corophiidae (p. 184) 



