Dictionary of Ichthyology  

ceratobranchial = a long, deep, endochondral bone in the middle portion of the gill arches between the epibranchials and the hypobranchials. There are usually 5 pairs of ceratobranchials, absent in some Anguillidae, Polypterus and Calamoichthys. The fifth pair of ceratobranchials are modified in Cypriniformes and Siluriformes into a strong, tooth-bearing bone called the inferior pharyngobranchial bone. Sometimes spelled keratobranchial.

Shark skull, a = auditory capsule, b = basibranchial, c = keratobranchial, e = epibranchial, g = gill cleft, h = hyoid, hm = hyomandibula, l = labial cartilages, m = mandible (Meckel's cartilage), o = olfactory capsule, p = pharyngobranchial, pq = pterygoquadrate, r = rostrum, s = spiracle, 2, 5 = exits of second and fifth nerves, I-V = branchial arches., from Kingsley's "Textbook of Vertebrate Zoology, 1906. Photograph by Brian W. Coad....more

Canadian Museum of Nature