514 GANOIDS. 



on the upper lobe of the tail, as we thus have evidence of the descent of the family 

 from fully scaled fishes. 



Toothless From the preceding family the typical sturgeons (Acipenseridce) 



sturgeons. ma y fo e distinguished by the absence of teeth in the adult, and the 

 presence of five longitudinal rows of bony plates on the naked body, which is 

 elongate and subcylindrical in form, as well as by the presence of four barbels in a 

 transverse line on the under surface of the muzzle. The muzzle is somewhat 

 produced, and either subspatulate or conical in form, with the small, transverse 

 mouth on its lower surface. All the vertical fins are armed with a single series of 

 fulcra on their front edges ; the dorsal and anal are situated at a moderate distance 

 from the caudal ; and the large air-bladder is simple. Confined to the temperate 

 regions of the Northern Hemisphere, sturgeons are either exclusively or partially 

 fresh-water fish, some of them only ascending rivers for the purpose of spawning, 

 after which they return to the sea. With the slender-beaked sturgeon, they 

 include the largest fresh-water fishes of this region, several of the species commonly 

 growing to 10 feet, while some are much larger. The females deposit enormous 

 numbers of extremely minute eggs, the product of a single individual having been 

 estimated at upwards of three millions during a season. This wonderful fecundity 

 easily accounts for the enormous numbers in which sturgeon, in spite of constant 

 persecution, still crowd the northern rivers during the spawning-season. In 

 addition to the excellence of their flesh, sturgeon are valued for their roe, from 

 which is manufactured caviare, and for their air-bladder, the inner coat of which 

 forms the basis of isinglass. In a fossil state sturgeons are unknown before the 

 upper part of the Eocene period. All the members of the genus are exceedingly 

 voracious fishes, and the majority are mainly carnivorous. During the winter 

 many or all of them crowd together, either in inlets of the sea, estuaries, or the 

 deep pools of rivers, where they undergo a kind of hibernation ; and it is stated 

 that in some localities they bury their noses in the mud, with their bodies and tails 

 standing vertically upwards like a series of posts. They increase very rapidly in 

 size ; and the eggs are hatched in five days. Although still abundant in the 

 northern rivers, in those of Central Europe sturgeon have greatly decreased in 

 numbers, and few really big fish are now taken. In the beginning of the year, 

 when they are still torpid, sturgeon are captured by breaking the ice, and stirring 

 up the mud at the bottom of their haunts with very long poles armed with barbed 

 prongs. As the fish seek to escape, some are stabbed with the spears ; and it is 

 said that half a score of large fish may be thus taken by a single fisherman. In 

 summer regular fishing-stations are established on the Russian rivers, where the 

 approach of a shoal is heralded by a watchman. Upwards of fifteen thousand 

 sturgeon have been taken in a day at one of these stations ; and when the fishing 

 is suspended for a short time, a river of nearly four hundred feet in width, and 

 five-and-twenty in depth has been known to be completely blocked by a solid 

 mass of fish. 



The common sturgeon (Acipenser sturio), of which a small 



' example is shown in the illustration facing p. 510, is the typical 



representative of the first genus, in which the rows of bony plates remain distinct 



from one another on the tail, spiracles are present on the head, the upper lobe of 



