CHAPTER XVI 



THE TELEOSTOMI, OR "PERFECT-MOUTHED" FISHES 



WHEN we consider that, roughly speaking, three-fourths of the 

 surface of the globe is covered by the sea, it is not surprising that 

 the creatures inhabiting the waters should far outnumber the 

 dwellers on the land. Fishes, in number of individuals, exceed 

 all other classes of vertebrates, and it is fairly safe to say that 

 this is also the case in regard to the number of species. No fewer 

 than 12,000 species of fishes are known, and of these about 11,500 

 belong to the sub-class Teleostomi, or " Perfect-mouthed " fishes. 

 The greater number of this extensive class of fishes is included in 

 the sub-order Teleostei, fishes characterised by having a bony 

 skeleton and being clothed with scales. The remaining Teleostomi 

 belong to a tribe of fishes forming a series of connecting links 

 between the gristly fishes sharks and rays and the bony fishes 

 herring, cod, salmon possessing some of the characters of both 

 classes. Between the different classes of fishes there is no hard- 

 and-fast line ; the various orders and families appear rather to 

 pass, by a succession of gradual steps, from one kind of fish to 

 another. 



To the intermediate tribe belong several extinct forms of fishes 

 which we need not consider here ; the most familiar existing repre- 

 sentatives are the Sturgeons, the Bony Pikes, and the Bow-fin 

 fishes of America. These " ganoid " fishes, as they are termed, are 

 clothed with scales which, instead of being thin and flexible, as 

 in the majority of living fishes, consist of strong, bony plates, 

 with a highly polished surface, forming a strong defensive armour. 

 The Common Sturgeon occurs in great numbers in the River Volga, 

 and is common also on the east coast of America. It is not infre- 

 quently caught in British waters, particularly in the North Sea 

 and at the mouths of large rivers. It is a somewhat bulky fish, 

 sometimes measuring 18 feet in length, with a tail like that of 



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