46 The Skeleton of the Fish 



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 



47 



FIG. 28. Roccus lineoius. Branchial arches. (After Starks.) 



40. Basibranchial. 43. Epibranchial. 46. Lower pharyngeals. 



41. Hypo-branchial. 44. Suspensory pharyngeal. 47. Gill-rakers. 



42. Ceratobranchial. 45. Upper pharyngeals. 



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. 



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 pharyn- 

 geals are grown together in one large bone. In the suckers 

 (Catostomidce) the lower pharyngeal preserves its resemblance 

 to a gill-arch. In the carp family (Cyprinidcs) retaining this re- 

 semblance, it possesses highly specialized teeth. 



Vertebral Column. The vertebral column is composed of a 

 series of vertebras, 24 in number in the striped bass and in 

 many of the higher fishes, but varying in different groups from 

 1 6 to 1 8 to upwards of 400, the higher numbers being evidence 

 of unspecialized or more usually degenerate structure. 



