The Osteocranium of the American Cyprinid Fish, Notropis bifrenatus, with an Annotated Synonymy of Teleost Skull Bones

Abstract

CONTRIBUTIONS to cyprinid skull morphology in the decades following publication of Sagemehl's classic monograph (1891) were summed up by Gregory (1933). Although the family Cyprinidae is probably the largest of the recognized fish families (Hubbs and Lagler, 1947), these were few. Sagemehl, besides, gave more than proportionate attention to the skulls of Catostomidae, Homalopteridae and Cobitidae. The systematic groups within the family are still based on superficial characters, and its immediate antecedents remain obscure (Guenther, 1868; Sagemehl, 1891; Regan, 1911; Gregory, 1933; Nichols, 1938; Berg, 1940; Tretiakov, 1945, 1946; Kryzanovsky, 1947). Teleostean skull morphology has since been enriched by important ontogenetic studies and by longer typological series, of both living and fossil provenience. The cyprinid skull in particular has begun to receive attention more commensurate with its importance. The subjects of the more important investigations are the ontogeny of the occipital region and Weberian ossicles (Nusbaum, 1908; Matveiev, 1929; de Beer, 1937: 140; Watson, 1939), and of the entire chondrocranium (Hubendick, 1942), the morphology of the ethmoid region (Starks, 1926), the pharyngeal process of the basioccipital (Chranilov, 1927), the pharyngeal teeth (Chu, 1935), the dermal bones related to the latero-sensory canals (Sagemehl, 1891; Allis, 1904; Tretiakov, 1945, 1946; Devillers, 1947; Lekander, 1949), and of the sensory canals themselves (Manigk, 1933; Devillers, 1944). Light is also shed on cyprinid skull morphology by the recent study of the homalopterid skull (Ramaswami, 1948). Published illustraLions of cyprinid skulls, however, even in the osteologies of particular species (Koh, 1931; Tchang, 1950; Tchang and Pao, 1934), fail to show clearly all the bones, and an up-todate nomenclature remains to be applied to all the skull bones of any one species. An attempt has been made here (1) to describe the skull of a cyprinid, making full use of existing terminology with special application to the group; (2) to illustrate clearly each bone in relation to adjacent bones; and (3) to name each bone in conformity with the present state of teleostean skull morphology. Synonymies of the more controversial bones are considered in alphabetical order, under the names used in the description and figures. These names represent, in general, resolutions of the often conflicting claims of paleontology, of different branches of morphology, and of usage, past and present, here and abroad. No problem of naming has been consciously avoided, and the explicit citation of authorities, invoked in justification of the names decided upon, should facilitate constructive criticism.