378 U.S. NATIONAL MUSEUM BULLETIN 271 



27. Posterior lobe on article 5 of gnathopod 2 guarding article 6 (fig. 1380- 



Monoculodes 

 Posterior lobe on article 5 of gnathopod 2 projecting at right angles. 



Oediceropsis 



28. Pereopods 1-2: article 7 absent Exoediceros 



Pereopods 1-2; article 7 present 29 



29. Eyes completely coalesced 30 



Eyes separated by a median line or space, or absent 31 



30. Eyes forming a semicircular ring Gulbarentsia 



Eyes forming a circle or oval Paraperioculodes 



31. Gnathopod 2: lobe of article 5, if large, projecting erectly at nearly right 



angles, not guarding article 6 32 



Gnathopod 2: lobe of article 5 projecting distally at angle of 45° or less, 



guarding article 6 36 



32. Eyes paired and lateral (theoretical possibility) Oediceropsis 



Eyes contiguous at midline or absent 33 



33. Maxilla 2, outer plate lacking stout spine 34 



Maxilla 2, outer plate bearing stout spine (often bifid) . . . Anoediceros 



34. Basal portion of flagellum on antenna 2 swollen. 



Subgenus Lopiceros (see Oediceroides) 

 Basal portion of flagellum on antenna 2 slender 35 



35. Coxae 3 or 4 excavate ventrally (fig. 1366), antennae subequal in length. 



Aceroides (incl. subgenus Patoides) 



Coxae 3 or 4 not excavate ventrally, antenna 1 very disproportionately 



shorter than antenna 2 Oediceroides { = Oediceropsoides) 



36. Coxa 4 excavate ventrally, rostrum very small or obsolete (fig. 137d), eyes 



absent Aceroides 



Coxa 4 not excavate ventrally; either rostrum large, extending more than 

 halfway along article 1 of antenna 1, or eyes present 37 



37. Article 3 of antenna 1 less than half as long as article 1 . . . . Monoculodes 

 Article 3 of antenna 1 as long as article 1 Monoculopsis 



Genera of Oedicerotidae 



Acanthostepheia Boeck 



Acanthostepheia Boeck, 1871. — Stebbing, 1906. 



Type-species: Amphithonotus malmgreni Goes, 1866 (monotypy). 

 See Stephensen, 1938. 



Cutting edge of mandible projecting and toothed, molar apparently 

 ridged; inner lobes of lower lip separate; gnathopods similar to each 

 other, subchelate, stout, article 5 with large posterior lobe projecting 

 at right angles; uropod 2 reaching end of uropod 3; body dorsally 

 multicarinate (combining character). Species: 3, arctic, littoral to 

 bathyal (552 m). 



Aceroides Sars 



Aceroides Sars, 1895. — Stebbing, 1906. 



Aceropsis Sars, 1895. 



(Patoides) J. L. Barnard, 1964a (subgenus). 



