The Collaborative International Dictionary of English v.0.48:

Platyrhini \Plat`y*rhi"ni\, n. pl. [NL., fr. Gr. ? broad + ?, ?,
   nose.] (Zool.)
   A division of monkeys, including the American species, which
   have a broad nasal septum, thirty-six teeth, and usually a
   prehensile tail. See Monkey. [Written also Platyrrhini.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

Platyrrhini
    n 1: New World monkeys: capuchin; douroucouli; howler monkey;
         saki; spider monkey; squirrel monkey; titi; uakari; woolly
         monkey; marmoset; tamarin [syn: Platyrrhini, superfamily
         Platyrrhini]