ACIPENSER GLABER. 387 



shaped, these scutes all have a heart-shaped base, and a blunt keel, which ends 

 in a slight hook. Their radiated ornament is feebly developed. The lateral 

 shields, according to Heekel, increase in number from thirty-five in the young 

 to sixty in the adult. They are lozenge-shaped, have only a slight ridge, and 

 decrease in size posteriorly. The lateral line is seen between them as a row of 

 small, round, bony scales, which overlap each other, like the slates on a roof. 

 The ventral shields are only twelve to fifteen in number. They are most 

 distinct in front, but are far apart, and are scarcely perceptible behind. There 

 are no shields on the tail, behind the vent and the dorsal fin. On the anterior 

 part of the belly behind the gill-openings, the surface is covered and defended 

 by two large shields, longitudinally keeled, pointed behind, and beautifully 

 sculptured with radiating rays. The skin between the rows of scutes is 

 thickly covered with small bony scutes, which are denticulated posteriorly, but 

 become smaller towards the belly, and lose their denticulations. 



The pectoral fin consists of a very strong bony ray, and thirty jointed soft 

 rays, of which the longest is equal to the thickness of the body. The length of 

 the base of the dorsal fin exceeds its height ; its end is opposite to the anal fin. 

 The height of the anal fin exceeds the length of its base, and it is longer than 

 the ventral fin. All these fins are truncated behind-. In the caudal fin the 

 long upper lobe has thirty-nine rays, and the lower has sixty-five jointed rays, 

 and sixteen unjointed rays. There is an unsymmetrical bony shield in front 

 of the lower lobe of the caudal, in front of the anal, and in front of the 

 dorsal fins. 



The colour of the back is reddish-grey, paler towards the sides. The belly 

 and lateral shields are dirty white. The barbels are white. The iris is yellow. 



The young in this species are distinguished by the form of the snout, 

 which is relatively longer, more pointed, and more curved upward, while 

 the median ridge on its under side is more strongly developed. Hence the re- 

 lative length of the head is then different, while the barbels are farther from 

 the extremity of the snout than in the adult. Moreover, the growth of the 

 shields is not proportionate to the growth of the body, so that in the young fish 

 the shields are nearer together in all the rows, while those of the back partly 

 overlap each other, and all have the keels sharper and hooks stronger. The 

 caudal fin is then less developed, and the lower lobe is scarcely one-third as 

 long as the upper. The pectoral fins, on the other hand, are remarkably de- 

 veloped in the young, and are nearly as long as the head. 



Acipenser glaber grows to a length of six or seven feet, and may attain a 

 weight of sixty pounds, but specimens of more than three or four feet length 

 are not often captured. 



