The Collaborative International Dictionary of English v.0.48:

Neritina \Ner`i*ti"na\, prop. n. (Zool.)
   A genus including numerous species of shells resembling
   Nerita in form. They mostly inhabit brackish water, and are
   often delicately tinted.
   [1913 Webster]

WordNet (r) 3.0 (2006):

neritina
    n 1: ornately marked and brightly colored snails of brackish
         waters