Source : Webster's Revised Unabridged Dictionary (1913)

Spirifer \Spi"ri*fer\, n. [NL., fr. L. spira a coil + ferreto
   bear.] (Paleon.)
   Any one of numerous species of fossil brachipods of the genus
   {Spirifer}, or {Delthyris}, and allied genera, in which the
   long calcareous supports of the arms form a large spiral, or
   helix, on each side.