392 MANUAL OF ZOOLOGY SECT. 



Cod, Sole, Herring, Eel, Salmon, etc., and the Ganoidei 

 such as the Sturgeon, Bony Pike (Lepidosteus) and Bow-fin 

 (Amid] of North America, and the Polypterus of the Nile. 

 They are distinguished from Elasmobranchs, among other 

 things, by the possession of an operculum or gill-cover, by the 

 absence of a cloaca, by having the primary skull and shoulder- 

 girdle complicated by the addition of membrane-bones, and 

 by possessing bony instead of horn-like fin-rays. 



A typical Teleostome, such as a Trout (Fig. 219) or a 

 Herring, has a long compressed body, nearly half of which 



op 



FIG. 219. Salmo fario. a. I. adipose lobe of pelvic fin ; an. anus ; c.j. caudal 

 fin ; d.f.i, first dorsal ; d.f.2, second dorsal or adipose fin ; /. /. lateral line ; 

 op. operculum; pct.f. pectoral fin ; fv.f. pelvic fin; v.f. ventral fin. (After 

 Jardine.) 



is formed by the tail, pointed anterior and posterior ends, a 

 large vertical tail-fin, a head of moderate size, and a terminal 

 mouth. Such a form is eminently fitted for progression 

 through the water. But from this characteristic fish-form 

 there are many striking deviations. The body may be 

 greatly elongated and almost cylindrical, as in the Eels ; or 

 of great length and strongly flattened from side to side as 

 in the Ribbon-fishes ; or the head may be of immense 

 proportional size and strongly depressed, as in certain shore- 

 fishes, such as the "Fishing-frog "; or, as in the beautiful Reef- 

 fishes, the whole body may be as high as it is long. The 



