perichaetous

from The Collaborative International Dictionary of English v.0.48

Perichaetous \Per`i*ch[ae]"tous\, a. [See {Perich[ae]tium}.]
   (Zool.)
   Surrounded by set[ae]; -- said of certain earthworms (genus
   {Perich[ae]tus}).
   [1913 Webster]