MARINE GAMMARIDEAN AMPHIPODA 115 



12. Telson cleft 13 



Telson entire 17 



13. Gnathopods powerfully subchelate (fig. 41c and like fig. QOq) .... 14 

 Gnathopods feeble (fig. 32d) 15 



14. Accessory flagellum 2 + -articulate, rostrum obsolescent, telson cleft 75 



percent of its length (fig. 41) liljeborgiidae (p. 291) 



Accessory flagellum absent, rostrum nearly as long as article 1 of antenna 1, 



telson cleft 40 percent of its length. 



Pseudamphilochus (Amphilochidae) (p. 139) 

 Accessory flagellum 0-1 articulate, rostrum obsolescent, telson cleft 25 



percent of its length Austropleustes (Pleustidae) (p. 422) 



15. Mandibular molar a conical or trapezoidal, setose lamina 16 



Mandibular molar a large setulose tuberosity. 



Synopia (Synopiidae) (p. 462) 



16. Accessory flagellum present (fig. 32) astyridae (p. 157) 



Accessory flagellum absent. 



Eclysis and Epimeriella (Paramphithoidae and Astyridae) (pp. 161, 389) 



17. Coxa 3 with about 3 times surface area of coxa 4, maxillipeds foliaceous, 



article 3 of mandibular palp vestigial, subequal to article 1 (fig. 165e) . 



Synopia (Synopiidae) (p. 462) 



Coxa 4 usually slightly larger than, subequal to, or scarcely smaller than 



coxa 3, maxillipeds not foliaceous, article 3 of mandibular palp much 



longer than article 1 18 



18. Coxae 1-4 wider (anterior-posterior) than long (dorsal- ventral) (fig. 



lllo) 19 



Coxae 1-4 longer than wide (fig. 37) . . . . 20 



19. Coxae contiguous or slightly overlapping. 



(exceptional) calliopiidae (p. 167) 

 Coxae not touching serially (fig. Ilia). 



Laphystiopsis (p. 285) and Prolaphystiopsis (Laphystiopsidae) (p. 285) 



20. Mandibular molar bulbous, ovate or cylindrical 21 



Mandibular molar a setose conical lamella . . (fig. 32) astyridae (p. 157) 



21. Article 4 of pereopods 1-2 enormously elongate (fig. 33/), accessory flagellum 



long and at least 3-articulate hypbriopsidae (p. 261) 



Article 4 of pereopods 1-2 of normal dimensions, accessory flagellum short or 

 absent and less than 3-articulate. 



pleustidae (p. 421) and calliopiidae (p. 167) 



22. Accessory flagellum usually (probably always) present and 3 + -articulate, 



maxillae not foliaceous (occasionally palp of maxilla 1 slightly foliaceous). 



(fig. 28) pardaliscidae (p. 397) 

 Accessory flagellum absent, vestigial or 2-articulate, extremely small, max- 

 illae foliaceous (fig. 29) stilipedidae (p. 451) 



SECTION H 



1. Pereopod 5 exceeding 1.5 times length of pereopods 3-4 i (fig. 27). 



oedicerotidae (p. 373) 

 Pereopod 5 scarcely longer than or shorter than pereopod 4 2 



2. Outer lobes of lower lip notched apically or medially excavate, outer ramus of 



uropod 3 bearing one or two giant, hooked, articulate spines, rami flattened. 



(fig. 50) ampithoidae (p. 141) 



Consult Aoridae if telson fleshy and pereopods 1-2 glandular. 



