444 U.S. NATIONAL MUSEUM BULLETIN 271 



Mandibular incisor toothed; i)ali) of maxilla 1 biarticulate; outer 

 plate of maxilla 2 geniculate, gaping; palp article 2 of maxillii)ed not 

 ])roduced ; article 2 of i)ereopods 3-4 slender, of |)ereopod 5 broad; 

 telson cleft halfway or more. S[)ecies: 3, arctic-boreal, littoral to 

 bathyal. 



Stegocephalus Kr0yer 



Stegocephalus Kr0yer, 1S42. — Stebbing, 1906. 



Type-species: S. infiatus Kr0yer, 1S42 (monotypy). See Sars, 1895. 



Mandibular incisor tootlied; ])alp of maxilla 1 uniarticulate; outer 

 plate of maxilla 2 geniculate, ga])ing; palj) article 2 of maxilli])ed not 

 l)roduced; article 2 of pereopod 3 slender, of i)ereopods 4-5 broad; 

 telson cleft half^\■ay; iipper lip, lower lip, and maxilla 1 not elongate; 

 spines oj outer plate of maxilla 2 with hooks {Stegocephalina) . Species: 

 2, subarctic-boreal, littoral to bathyal. 



Steleuthera J. L. Barnard 



Steleuthera J. L. Barnard, 1964a. 



Type-species: S. maremhoca J. L. Barnard, 1964a (original 

 designation) . 



Mandibular incisor toothed; palp of maxilla 1 uniarticulate; outer 

 plate oj maxilla 2 not geniculate (Stegocephaloides) ; palp article 2 of 

 maxilliped not produced; article 2 of pereopods 3-4 slender, of pereo- 

 pod 5 broad; telson poorly cleft. Species: 1, Peru, hadal. 



Tetradeion Stebbing 



Tetradeion Stebbing, 1899d; 1906. 



Type-species: Cyproidia crassa Chilton, 1883 (original designa- 

 tion). See Hurley, 1955. 



Mandibular incisor toothed; palp of maxilla 1 biarticulate; outer 

 plate of maxilla 2 geniculate, gaping; palp article 2 of maxilliped 

 distomedially produced; article 2 of pereopods 3-4 slender, of pereopod 

 5 broad; pereopod 5 with only three articles; telson entire. Species: 1, 

 New Zealand, littoral. 



Stenothoidae 



Figure 162 



Diagnosis. — Accessory flagellum absent or composed of one or 

 two vestigial articles; mandibular molar evanescent; coxa 1 very 

 small, always partially covered by folio ^ving coxae; coxa 4 enlarged, 



