The gill-arches are suspended to the cranium from above by the _suspensory pharyngeal_ (44). Each arch contains three parts--the _epibranchial_ (43), above, the _ceratobranchial_ (42), forming the middle part, and the _hypobranchial_ (41), the lower part articulating with the series of _basibranchials_ (40) which lie behind the epihyal of the tongue. On the three bones forming the first gill-arch are attached numerous appendages called _gill-rakers_ (47). These gill-rakers vary very greatly in number and form. In the striped bass they are few and spear-shaped. In the shad they are very many and almost as fine as hairs. In some fishes they form an effective strainer in separating the food, or perhaps in keeping extraneous matter from the gills. In some fishes they are short and lumpy, in others wanting altogether. [Illustration: FIG. 28.--_Roccus lineatus._ Branchial arches. (After Starks.) 40. Basibranchial. 41. Hypobranchial. 42. Ceratobranchial. 43. Epibranchial. 44. Suspensory pharyngeal. 45. Upper pharyngeals. 46. Lower pharyngeals. 47. Gill-rakers.] =The Pharyngeals.=--The hindmost gill-arch, as above stated, is modified to form a sort of jaw. The tooth-bearing bones above, 2 to 4 pairs, are known as _upper pharyngeals_ (45), those below, single pair, as _lower pharyngeals_ (46). Of these the lower pharyngeals are most highly specialized and the most useful in classification. These are usually formed much as in the striped bass. Occasionally they are much enlarged, with large teeth for grinding. In many families the lower pharyngeals are grown together in one large bone. In the suckers (_Catostomidæ_) the lower pharyngeal preserves its resemblance to a gill-arch. In the carp family (_Cyprinidæ_) retaining this resemblance, it possesses highly specialized teeth. =Vertebral Column.=--The vertebral column is composed of a series of vertebræ, 24 in number in the striped bass and in many of the higher fishes, but varying in different groups from 16 to 18 to upwards of 400, the higher numbers being evidence of unspecialized or more usually degenerate structure. Each vertebra consists of a double concave body or _centrum_ (66). Above it are two small projections often turned backward, _zygapophyses_ (71), and two larger ones, _neurapophyses_ (67), which join above to form the _neural spine_ (68) and thus form the _neural canal_, through which passes the spinal cord from end to end of the body. [Illustration: FIG. 29.--Pharyngeal bone and teeth of European Chub, _Leuciscus cephalus_ (Linnæus). (After Seelye.)] [Illustration: FIG. 30.--Upper pharyngeals of a Parrot-fish, _Scarus strongylocephalus_.] [Illustration: FIG. 31.--Lower pharyngeals of a Parrot-fish, _Scarus strongylocephalus_ (Bleeker).]