18 BRITISH FRESHWATER FISHES 



examples, but is nearer to the end of the snout in 

 large fish. The dorsal fin is placed far back, and is 

 composed of from thirty-seven to forty-six rays ; the 

 anal, which begins below the middle of the dorsal and 

 extends a little farther back than that fin, has twenty- 

 four to twenty-nine rays, and the pelvic fins have the 

 same number. There are from ten to sixteen scutes 

 in the dorsal series between the head and the dorsal 

 fin, and from nine to fourteen in each ventral series 

 between the pectoral and pelvic fins ; the lateral series 

 increases in number to some extent with age, owing 

 to the addition of small scutes posteriorly; in 1870 

 Dr. Giinther counted the lateral scutes on a number 

 of European examples, and found twenty-six to 

 thirty-one in the young, but twenty-nine to thirty- 

 four in half-grown and adult fish. A larger series of 

 specimens would no doubt have shown greater varia- 

 tion ; thus Day found only twenty-seven scutes on 

 one side and twenty-eight on the other in an adult 

 fish more than 5 feet long, from Margate, whilst in a 

 specimen 18 inches long, from the Adriatic, I count 

 thirty-four on one side and thirty-five on the other, 

 and in one of 30 inches, from the Gironde, I count 

 forty on each side, and after careful comparison I am 

 convinced that these are true Acipenser sturio. It has 

 been assumed that specimens with a large number of 

 lateral scutes, as, for example, one said to be from 

 the Tay, with thirty-eight on one side and forty on 

 the other, belong to an American species (A. macu- 

 losus\ which has been supposed to cross the Atlantic 

 occasionally ; probably they cannot be distinguished 

 from American examples named Acipenser maculosus, 

 but I am unable to separate these specifically from 

 other American specimens with fewer scutes, named 



