The Collaborative International Dictionary of English v.0.48:

Actinotrocha \Ac`ti*not"ro*cha\, n. pl. [NL.; Gr. ?, ?, a ray +
   ? a ring.] (Zool.)
   A peculiar larval form of Phoronis, a genus of marine
   worms, having a circle of ciliated tentacles.
   [1913 Webster]