epibranchial

from The Century Dictionary.

• Literally, upon the gills: applied in zoölogy— to a part of a bird's hyoid bone (see II.);
• in brachyurous crustaceans, to an anterior division of the carapace forming part of the roof of the branchial chamber. See cut under Brachyura.
• noun In ornithology, the posterior or terminal element of the long-horn of the hyoid bone, an osseous element developed in the third postoral (first branchial) visceral arch of a bird, forming the end-piece of the complex hyoid bone, borne upon the ceratobranchial. It is the ceratobranchial of some, the ceratohyal of others.
• noun In ichthyology, one of the upper bones of the gill-arches.

from the GNU version of the Collaborative International Dictionary of English.

• adjective (Anat.) Pertaining to the segment between the ceratobranchial and pharyngobranchial in a branchial arch.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Pertaining to the segment between the ceratobranchial and pharyngobranchial in a branchial arch.
• noun An epibranchial cartilage or bone.