The Collaborative International Dictionary of English v.0.48:

Heterotricha \Het`e*rot"ri*cha\, n. pl. [NL., fr. Gr. ? other +
   ?, gen. ?, a hair.] (Zool.)
   A division of ciliated Infusoria, having fine cilia all over
   the body, and a circle of larger ones around the anterior
   end. Heterotropal