Branchial

a.
  1. Of or pertaining to branchiæ or gills.
    2. Branchial arches ,
    the bony or cartilaginous arches which support the gills on each side of the throat of fishes and amphibians. See Illustration in Appendix.
    Branchial clefts ,
    the openings between the branchial arches through which water passes.