Source : Webster's Revised Unabridged Dictionary (1913)

Peritricha \Pe*rit"ri*cha\, n. pl. [NL., fr. Gr. ? about + ?, ?,
   hair.] (Zo["o]l.)
   A division of ciliated Infusoria having a circle of cilia
   around the oral disk and sometimes another around the body.
   It includes the vorticellas. See {Vorticella}.