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.
Visceral arch of Scyllium (= Scyliorhinus), BH = basihyal, C = copula (united basibranchials), E = epihyal, H = hypohyal, HM = hyomandibula, HY = hyoid, K = keratobranchial, P = pharyngobranchial, from Kingsley's "Textbook of Vertebrate Zoology, 1906. Photograph by Brian W. Coad.

           Canadian Museum of Nature