310 U.S. NATIONAL MUSETJM BULLETEST 271 



Mandible with triturative molar, gnathopod 1 subchelate, article 2 of pereo- 

 pod 3 not deeply indentured Valettiopsis 



8. Lobes of maxilla 2 broadly separated, inner lobe pointing medially and of 



different shape or much broader than outer lobe (fig. 127 j) 9 



Lobes of maxilla 2 appressed and similar in shape (fig. 127Z) 10 



9. Telson cleft Ambasiella and Aristias (see Key O, couplet 2) 



Telson entire Perrierella 



10. Eyes and gnathopod 1 powerfully developed (fig. 123a) 11 



Eyes and gnathopod 1 not together powerfully developed 13 



11. Gnathopod 1 with complete torsion distal from article 4 (fig. ISOh), 



dactyl and palm thus posterior, mandibular molar needle-like (fig. 1266), 



telson scarcely longer than broad (fig. 128m-') Trischizostoma 



Gnathopod 1 untwisted, normal, mandibular incisor broad, flat, telson 

 elongate, much longer than broad 12 



12. Gnathopod 1 chelate, palm thus deeply excavate (fig. r29e) . . . Opisa 

 Gnathopod 1 cheliform only, palm convex and protuberant (fig. 1290- 



some species of Cheirimedon 



13. Palp article 4 of maxilliped vestigial (figs. 128d, e, i) 14 



Palp article 4 of maxilliped well developed, claw-like 17 



14. Lobes of maxilla 2 strongly setose, telson deeply cleft 15 



Lobes of maxilla 2 with one and four setae, respectively (fig. 127/c), telson 



scarcely cleft Adeliella 



15. Maxilla 1 with palp 16 



Maxilla 1 lacking palp continue to couplet 21 



16. Epistome and labrum coalesced, labral portion not projecting (epistome 



often projecting), mandible without molar . Ambasia and Ambasiella 



Epistome and labrum separated by notch, labral portion slightly projecting, 



mandible with molar Centromedon 



17. Mandibular molar distinctly toothed and ridged (fig. 126g) 18 



Mandibular molar untoothed and unridged (fig. 12Qi), or ridges forming 



marginal girdle only (fig. 126d), often fuzzy, or molar absent .... 19 



18. Liner ramus of uropod 2 incised, outer ramus of uropod 3 biarticulate. 



Aristiopsis and Schisturella ^ 

 Liner ramus of uropod 2 simple, outer ramus of uropod 3 uniarticulate. 



Tryphosoides 



19. Gnathopod 1 chelate (chela and gnathopod slender) . Podoprion and Euonyx 

 Gnathopod 1 subchelate or simple 20 



20. Gnathopod 1 simple 21 



Gnathopod 1 subchelate (often minutely so) or chelate 23 



21. Anteroventral corner of coxa 4 acutely produced Vijaya 



Anteroventral corner of coxa 4 rounded or quadrate 22 



22. Article 2 of antenna 1 half as long as article 1 Amaryllis 



Article 2 of antenna 1 fully as long as article 1 Bathyamaryllis 



23. Inner plate of maxilla 1 with one or two immense falcate setae (fig. r27<i). 



(cf. Cheirimedon pectinipalma K. H. Barnard, 1925) Hirondellea 

 Liner plate of maxilla 1 with normal setae 24 



24. Inner plate of maxilla 1 with five or more setae (adults) 25 



Inner plate of maxilla 1 with three or fewer setae 27 



And see Key L, couplet 10, for "Orchomenella" groenlandica (Hansen). 



