MARINE GAMMARIDEAN AMPHIPODA 111 



6. Uropod 3 uniramous 7 



Uropod 3 biramous 10 



7. Coxa 1 visible, not covered by following coxae 8 



Coxa 1 small and hidden by large following coxae 9 



8. Mandible lacking palp, bearing molar, inner plates of maxillipeds obsolescent, 



telson cleft (fig. 13) kuriidae (p. 280) 



Mandible bearing palp, lacking molar, inner plates of maxillipeds fully 

 developed, telson entire (fig. 14) pagetinidae (p. 387) 



9. Telson and pleonite 6 coalesced even though telson recognizable and un- 



thickened, article 2 of pereopod 3 expanded, (fig. 16) cressidae (p. 198) 

 Telson thickened dors o ventral ly and distinct from urosome, but urosomites 

 partially coalesced, article 2 of pereopod 3 linear. 



(fig. 17) THAUMATELSONIDAE (p. 473) 



10. Mandibular palp absent 11 



Mandibular palp present 12 



11. Only urosomites 2-3 coalesced (fig. 23) dexaminidae (p. 200) 



Urosomites 1-3 coalesced (fig. 22) prophliantidae (p. 432) 



12. Pereopod 5 of different structure and almost always shorter than pereopod 4 



(fig. 26) ampeliscidae (p. 128) 



Pereopod 5 similar and subequal to or longer than pereopod 4 (or these 

 pereopods often broken or missing) 13 



13. Telson entire or slightly emarginate 14 



Telson cleft or deeply emarginate 16 



14. Urosomite 1 elongate (fig. 52) podoceridae (p. 426) 



Urosomite 1 not elongate, or all urosomites coalesced 15 ^ 



15. Uropods 1 and 2 of extremely diverse structure (fig. 53). 



CHELURIDAE (p. 180) 



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



(fig. 51) COROPHIIDAE (p. 184) 



16. Coxae 1-4 rounded, quadrate or blunt ventrally. 



(fig. 25) ATYLIDAE (p. 161) 



One or more of coxae 1-4 acuminate ventrally and often bifid (fig. 24) . 



LEPECHINELLIDAE (p. 286) 



I See Paracalliope in supplement. 



SECTION D 



1. Gnathopod 1 reduced to one or two articles or absent (figs. 20, 30) ... 2 

 Gnathopod 1 present, comprising six or seven articles 3 



2. Mouthparts all present and normal (fig. 30) bateidae (p. 163) 



Mandibles and maxillae absent or coalesced into sharp keel (fig. 20) 



anamixidae (p. 145) 



3. Pereopods 3-5 fossorial, article 4" of antenna 2 strongly expanded, antennae 



with plumose setae longer than any antennal article. 



(exceptional) haustoriidae (p. 248) 



Pereopods 3-5 usually not fossorial but if fossorial then article 4 of antenna 



2 not expanded, setae of antennae not elongate plumes 4 



4. Gnathopod 1 strongly carpochelate, carpus larger than propodus (or ap- 



pearing as propodochelate because of loss of dactyl) (fig. 20) 5 



Gnathopod 1 subchelate or simple, or carpus smaller than propodus (oc- 

 casionally carpus with long lobe but not distinctly chelate) 6 



5. Mouthparts except maxilliped replaced by a ventral keel and bulbs. 



(fig. 20) ANAMIXIDAE (p. 145) 



