The Collaborative International Dictionary of English v.0.48:

Pseudonavicula \Pseu`do*na*vic"u*la\, n.; pl.
   Pseudonavicul[ae]. [NL., fr. Gr. pseydh`s false + NL.
   navicula, a genus of diatoms. See Navicular.] (Zool.)
   One of the minute spindle-shaped embryos of Gregarin[ae] and
   some other Protozoa.
   [1913 Webster]