Propterygia

from The Collaborative International Dictionary of English v.0.48

Propterygium \Prop`te*ryg"i*um\, n.; pl. {Propterygia}. [NL.,
   fr. Gr. ? before + ? a fin.] (Anat.)
   The anterior of three principal cartilages in the fins of
   some fishes. -- {Prop`ter*yg"i*al}, a.
   [1913 Webster]