120 U.S. NATIONAL MUSEUM BULLETIN 271 



Mandible not drawn out in a long, needle-like apex 14 



14. Palp of maxilla 1 enormously expanded into an ovate lamina, upper lip 



asymmetrically incised (fig. 55e), lower lip not incised (fig. 566). 



Maxilliphimedia 

 These characters not combined 15 



15. Palp article 2 of maxilliped distinctly produced along medial edge of article 



3 (fig. 56i), outer lobes of lower lip apically and strongly notched (fig. 



56a) 16 



Palp article 2 of maxilliped indistinctly or not produced along medial edge 

 of article 3 (figs. 5Qg,h), outer lobes of lower lip unnotched or very weakly 

 notched 17 



16. Pereonite 1 as long as next three segments combined (fig. 55m), mandibular 



incisor apparently absent Cypsiphimedia 



Pereonite 1 not longer than each of next three segments (fig. 55a), mandibular 

 incisor strong Iphimedia ^ 



17. Upper lip deeply incised (fig. 55d), first two articles of maxillipedal palp 



extraordinarily broadened (fig. 56/) Pseudiphimediella 



Upper lip entire or emarginate, first two articles of maxillipedal palp not 

 broadened (fig. 56^) 18 



18. Some or all coxae with submarginal teeth Echiniphimedia 



Coxae lacking submarginal teeth 19 



19. Primary cutting edge of mandible multidentate (figs. 55h,j). 



Pariphimediella 

 Primary cutting edge of mandible 2- or less dentate (fig. 550 20 



20. Mandible short, stout, primary cutting edge very broad, smooth, molar 



conical (fig. 55i) Gnathiphimedia 



Mandible slender, long, primary cutting edge tapering, subacute, molar if 

 present, not conical (fig. 55Z) Iphimediella 



1 See also Panoploea spinosa Thomson (Hurley, 1954c) which keys here because of its scarcely shortened 

 palp of maxilla 1. 



Genera of Acanthonotozomatidae 



Acanthonotozoma Boeck 



Acanthonotus Ross, 1835 (homonym, Pisces). 



Acanthonotozoma Boeck, 1876 (new name for Acanthonotus) . — Stebbing, 1906. 



Type-species: Acanthonotus cristatus Ross, 1835 (original designa- 

 tion). See Sars, 1895. 



Upper lip incised; mandible with narrow, rounded apex; lobes of 

 lower lip not incised; palp of maxilla 1 biarticulate, reaching or exceed- 

 ing end of outer plate; maxillipedal palp exceeding outer plate, 

 4-articulate, article 2 not produced; gnathopods simple, gnathopod 1 

 very slender, feeble, gnathopod 2 stouter than 1; telson apically 

 incised. Species: 4, arctic-boreal, littoral (rarely to 700 m). 



