The Collaborative International Dictionary of English v.0.48:

Coccygeal \Coc*cyg"e*al\, a. (Anat.)
   Of or pertaining to the coccyx; as, the coccygeal
   vertebr[ae].
   [1913 Webster]

   Coccygeal glands (Zool.), glands situated at the base of
      the tail of birds. They secrete the oil with which the
      plumage is dressed.
      [1913 Webster]