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 b 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 



