SUPPLEMENT ON CHONDROPTERYGII. 625 



supposed worms, find themselves in the jaws of the stur- 

 geons. 



The operculum is marked by a number of concentric 

 striae, and the body is armed with five series of hard tuber- 

 cles, terminating in a spine more or less obtuse, but bent. 



The sturgeon is found almost every where in the main 

 ocean, as well as in the circumscribed and narrow seas ; and 

 at certain times of the year, in all the larger rivers ; some- 

 times even it is found wandering in tributary streams, at 

 considerable distances from the tide-rivers or the sea. They 

 are sometimes found in the Thames, but more commonly in 

 our northern rivers, especially the Eden and the Esk ; in 

 which latter river one was caught a few years ago, which 

 weighed 460 pounds. The common sturgeon, though not so 

 large as another species we shall have occasion to mention, 

 attains to a great length ; the ordinary size, however, as 

 found in our rivers, is about six feet, and it is remarkable 

 that they are seldom taken very small or young, whence it 

 has been presumed, that the young, as soon as they escape 

 from the eggs, which the female deposits up the river, 

 descend immediately to deep water in the sea, and do not 

 visit the places of their birth again, till they come in their 

 turn to deposit their eggs. 



It is in the rivers of the northern parts of Europe that 

 these fish most abound, especially in March, April, and 

 May. They enter then in shoals so abundant, as to produce 

 a visible effect on the surface of the water. Pallas was in- 

 formed, that they have been in such numbers in the Jaick, 

 as to endanger the embankments made in that river; and 

 that it has been thought necessary to frighten them back, by 

 discharge of cannon. They appear to be more rare in the 

 rivers of Siberia, which are of great rapidity, and have a 

 stony bed. They are found more or less, not merely in the 

 rivers of Northern Asia, but in those which fall into the 



VOL. X. s s 



