\Bran`chi*os"te*gal\, a. [Gr. ? gill + ? to
cover: cf. F. branchiost[`e]ge.] (Anat.)
Pertaining to the membrane covering the gills of fishes. --
n. (Anat.) A branchiostegal ray. See Illustration of
{Branchial arches} in Appendix.
Note: This term was formerly applied to a group of fishes
      having boneless branchi[ae]. But the arrangement was
      artificial, and has been rejected.