FISHES. 



269 



The Cartilaginous Fishes are divided into three orders. 

 1. STUBIONES (Sturgeons). 



Sturgeons (fig. 44) are inhabitants of the northern seas, but 

 are occasionally found in our rivers. They have rows 

 of bony plates imbedded in the skin ; they sometimes 



FIG. 44. THB STUEGEON (Accipeuser sturio). 



attain the length of twenty feet, but are usually from 

 six to eight feet long. Isinglass is made of the 

 swimming bladder of the Sturgeon, and the roe (dried 

 and salted) forms the "Caviare." 



2. PLAGIOSTOMI (Wide-mouthed). 



The Plagiostomi comprise the Sharks (fig. 45) and Dog- 

 fishes, a most voracious tribe ; the White Shark often 



FIG. 45. THE SHAEK (Carcharias vulgaris). 



attains the length of twenty feet. They are terribly 

 famous for their dreadful powers of destruction, swallow- 

 ing all that comes before them ;_ they are able to bite in 



