XVIII CHONDROSTEI 493 
species, but the exact number is uncertain. Sturgeons are abundant 
in the Black Sea, the Sea of Azov, the Caspian, and their tribu- 
tary rivers, notably the Danube, Don, Dnieper, Ural, and Volga. 
They are also present in the rivers and on the coasts of Northern 
Europe and of China. Five species occur in North America, on 
the Atlantic and Pacific coasts, and in the rivers of these regions 
as well as in the Great Lakes." One or two species are almost 
exclusively fresh-water, but most Sturgeons are migratory Fishes, 
living in the sea, but ascending rivers for spawning. Their food 
consists of worms, molluscs, the smaller Fishes and aquatic 
plants; and in feeding the mouth is protruded downwards in 
the form of a cylindrical, spout-like structure and thrust into the 
mud. The only species certainly known to frequent the British 
Fic. 290.—The Sterlet (Acipenser ruthenus). 0, Barbels; c.f, caudal fin; d.f, dorsal 
fin ; pet.f, pectoral fin ; pv.f, pelvic fin ; sc, scutes ; v.f, ventral or anal fin. (From 
Parker and Haswell, after Cuvier.) 
coasts is the common Sturgeon (A. sturio), which is also found 
in the Black Sea and the Mediterranean, and is abundant on the 
Atlantic coast of North America from Maine to South Carolina. 
The species occurs all round our coasts, more plentifully, perhaps, 
on the northern and eastern shores. In the spring and summer 
the Fish ascends the rivers, often to a considerable distance. Its 
presence has been recorded in the Severn, near Shrewsbury ; in 
the Trent at Nottingham, and also, but not in recent years, in 
the Thames above London Bridge.” In this country the species 
is a “ Royal Fish,” and by an unrepealed Act of Edward II. it is 
enacted that “the King shall have the wreck of the sea through- 
out the realm, Whales and Great Sturgeons, except in certain 
places privileged by the King.”* If not so large as some of its 
Russian relatives, A. sturio often attains a great size. Even on 
1 Jordan and Evermann, op. cit. p. 102. 
2 Day, Fishes of Great Britain and Ireland, ii. 1880-84, p. 282. 
3 Id, op. cit. p. 279. 
