The Ganoids 19 



ing smaller streams to spawn. Other sturgeons are marine, 

 ascending fresh waters only for a moderate distance in the 

 spawning season. They range in length from 2^ to 30 feet. 



All are used as food, although the flesh is rather coarse 

 and beefy. From their large size and abundance they possess 

 great economic value. The eggs -of some species are prepared 

 as caviar. 



The sturgeons are sluggish, clumsy, bottom-feeding fish. 

 The mouth, underneath the long snout, is very protractile, 

 sucker-like, and without teeth. Before it on the under side 

 of the snout are four long feelers. Ordinarily the sturgeon feeds 

 on mud and snails with other small creatures, but I have seen 



FIG. 6. Common Sturgeon, Acipenser sturio Mitchill. Potomac River. 



large numbers of Eulachon (Thaleichthys) in the stomach of 

 the Columbia River sturgeon (Acipenser transmontanus} . This 

 fish and the Eulachon run in the Columbia at the same time, 

 and the sucker-mouth of a large sturgeon will draw into it num- 

 bers of small fishes who may be unsuspiciously engaged in 

 depositing their spawn. In the spawning season in June these 

 clumsy fishes will often leap wholly out of the water in their 

 play. The sturgeons have a rough skin besides five series of 

 bony plates which change much with age and which in very 

 old examples are sometimes lost or absorbed in the skin. The 

 common sturgeon of the Atlantic on both shores is Acipenser 

 sturio. Acipenser huso and numerous other species are found 

 in Russia and Siberia. The great sturgeon of the Columbia 

 is Acipenser transmontanus, and the great sturgeon of Japan 

 Acipenser kikuchii. Smaller species are found farther south, 

 as in the Mediterranean and along the the Carolina coast. Other 

 small species abound in rivers and lakes. Acipenser rubicundus 

 is found throughout the Great Lake region and the Mississippi 

 Valley, never entering the sea. It is four to six feet long, and 

 at Sandusky, Ohio, in one season 14,000 sturgeons were taken 



