What is "holocephali"

Holocephali \Hol`o*ceph"a*li\, n. pl. [NL., from Gr. "o`los whole + kefalh` head.] (Zo["o]l.) An order of elasmobranch fishes, including, among living species, only the chim[ae]ras; -- called also Holocephala. See Chim[ae]ra; also Illustration in Appendix.

The subclass Holocephali ("complete heads") is a taxon of cartilaginous fish in the class Chondrichthyes. The earliest fossils are of teeth and come from the Devonian period. Little is known about these primitive forms, and the only surviving group in the subclass is the order Chimaeriformes. This group includes the rat fishes in the genus Chimaera, and the elephant fishes in the genus Callorhynchus. These fishes move by using sweeping movements of their large pectoral fins. They have long slender tails and live close to the seabed feeding on benthic invertebrates. They lack a stomach, food moving directly into the intestine.