494 FISHES CHAP. 



our own coasts the capture of individuals 8 to 1 feet in length 

 has been recorded. The great Kussian Sturgeon (A. huso], which 

 is common in the Black Sea, the Sea of Azov and the Caspian, 

 and in the rivers flowing into them, is the largest of all the 

 Sturgeons, individuals weighing 2760 and 3200 pounds having 

 been captured. The Sterlet (A. ruthenus), similarly distributed 

 and often ascending the Danube to Vienna, is much smaller, 

 rarely exceeding a length of three feet. 



In Europe A. sturio spawns about July, but in North 

 America (Delaware river) during May. Small in size, the eggs 

 are produced in enormous numbers, a single female, it is said, 

 producing about 3,000,000 in one season. They are invested 

 by a gelatinous sheath, so that they readily stick to one another 



b. m. 



op 



p't.f 



FIG. 291. Larval Acipenser ruthenus. a, Anus ; b, Larbels ; e, eye ; g, gills ; ??i, 

 mouth, with teeth ; ol.o, olfactory organ ; op, operculum ; pt.f, pectoral tin ; sp, 

 spiracle. x 10. (From Kitchen Parker.) 



or to other objects, and, when deposited, they adhere in streaks 

 or sheet-like masses to the bed of the river. The young are 

 hatched very early, about the third or fourth day in A. sturio, 

 and in the Sterlet between the ninth and twelfth, the length of 

 the larva then varying from 7 to 10 mm. When they are a few 

 days old the larvae closely resemble those of existing Holostei 

 except that the small opercular folds leave the gills freely ex- 

 posed (Fig. 291). A shallow pigmented groove in front of the 

 mouth apparently represents the sucker of the young Amia and 

 Lepidosteus. Although toothless in the adult, both the Sturgeon 

 and Sterlet possess vestigial rudimentary, uncalcified, larval teeth, 

 which in shape resemble the teeth of a Dog-Fish, consisting of a 

 broad base and a sharp spine. 



The Sturgeon is a Fish of considerable economic importance. 

 The flesh is an article of food, and from the ovaries of certain 

 Eussian and American species thousands of hundredweights of 



