THE COMMON STUHGEON. 



45 



thick. It contained an imperfectly-developed young one, which was five feet broad, and weighed 

 twenty pounds. A second species of the genus is recorded from the Red Sea. 



ORDER V. CHONDROSTEL* 



FAMILY I. ACIPENSERID.E, STURGEONS. 



The Sturgeons form a small and natural group of fishes, distinguished by having a cartilaginous 

 skeleton. They have the head covered with bony plates, and the body armoured with five rows of 

 bony bucklers, or scutes, which give it an angular character. The snout is pointed and conical. The 

 mouth opens in a large but short tube below the eye on the under side of the head, and is destitute 

 of teeth. Both jaws are formed of two cartilages, covered with a thin layer of bone. There are 

 only two genera of Sturgeons known. Nineteen species belong to the genus Acipenser , while the 

 second genus, called the Shovel-head (Scaphirhynchus), is represented by a single species (S. 

 catajrftractus), found in the Mississippi and its tributaries. It differs from the other Sturgeons in 

 wanting spiracles, and in having the bony scutes uniting with each other on the hinder part of the 

 tail, so as to envelop it in continuous armour. The nostrils in Sturgeons are double, and placed in 

 front of the eye, and there are four bai-bels arranged in a transverse series in front of the mouth on 

 the under side of the snout. There are no bony rays for the support of the gills, but there are four 



COMMON STURGEON. 



true gills and two accessory gills. The dorsal and anal fins are placed near to the caudal fin, which 

 is unequally lobed or formed on the heterocercal plan usual among Sharks. Where the skin 

 is not covered by the bony plates it is soft and covered with pores, which secrete mucus. The 

 Sturgeons swim low, and feed on the decaying substances, animal and vegetable, which sink to the 

 bottom of rivers and estuaries. These fishes have always been valued for their roe, which is known 

 to us under the name of caviare. The eggs are deposited without being contained in cases, much in 

 the same way as the eggs of bony fishes. A specimen which weighed 273 Ibs. had the roe weigh- 

 ing 42 Ibs., and in this there were computed to be two millions of eggs. 



The life of the Sturgeon has been observed only after it has ascended rivers. It moves along 

 with a gentle motion which suggests crawling rather than swimming, stirring up the mud and sand 

 with its snout seeking for food. In the breeding season some species feed almost exclusively on small 

 fishes allied to the Carp. They travel along the rivers between March and the latter part of autumn, 

 but hibernate during the winter. Caviare is prepared from the roe in a very simple way. Usually it 

 is beaten up and passed through a sieve to separate the eggs from the tissue in which they are 

 contained. Salt is then added, and the eggs are packed in barrels for exportation. Another method 

 of preparation is to remove the larger filaments of connective tissue, then salt, and dry in sun ; it is 

 next forced into barrels with the pressure of the feet. Better caviare is made by salting the roes in 

 long troughs. They are then placed in fine sieve troughs, while the eggs are pressed through into 

 small kegs. The best is obtained from the Acipenser stellatus and Acipenser ruthenus. 



The fishing in winter is carried on, according to Brehm, in a singular way. The rivers are 

 frozen over ; and the fish which have hibernated bury their snouts in the mud so as to leave the 



* Chondros, cartilage, and osteon, bone. 



