Sagittocyst

from The Collaborative International Dictionary of English v.0.48

Sagittocyst \Sag"it*to*cyst\, n. [See {Sagitta}, and {Cyst}.]
   (Zool.)
   A defensive cell containing a minute rodlike structure which
   may be expelled. Such cells are found in certain Turbellaria.
   [1913 Webster]