FISHES. 



553 



in all the great European rivers, and this species is in a fair way of 

 disappearing altogether. 



The Common Sturgeon. Acipenser sterio (Fig. 364), abounds in 

 the North Sea and the Mediterranean, and occasionally it appears in 

 the Thames, as well as here and there on the British coasts ; in the 

 Rhine, the Seine, the Loire, and the Gironde. It is usually from 

 six to seven feet long, but has been known to attain the length of 



Fig. 364. The Common Sturgeon (Acipenser sturio). 



nine or ten feet. Its general colour is yellow, with a white belly. It 

 is rendered remarkable by the number and form of the osseous 

 plates or scales, which cover the body like so many bucklers. Upon 

 the back and belly are no less than twelve to fifteen of these rough 

 bony plates, relieved by projections, which are pointed in the young, 

 and are worn down with age. On each side is a row of thirty to 

 thirty-five of these triangular ganoid plates, separated from each other 

 by considerable intervals. The head is broad at the base, gradually 

 contracting towards the point, and terminating in a conical muzzle. 

 The mouth is large, and placed considerably behind the extremity of 



