THE STURGEON FAMILY 35 
in the oldest, and therefore the first, sub-class of the class 
of Fishes. 
The Sturgeon Family includes two genera only, whereof 
the first, -4cipenser, consists of about twenty species, all bearing 
a remarkable resemblance to each other, and comprising the 
largest fresh-water fish of the Northern Hemisphere. The 
body is much elongated and nearly cylindrical ; the skin is 
protected by ridged bony plates or “ scutes,” arranged in five 
longitudinal rows, one along the back, two along the upper 
region of the sides, and two along the lower or ventral region. 
The sharply-angled keels or ridges of these plates give the fish 
a strangely antique appearance, and suggest a pentagonal form 
of body. The interval between the plates is covered with small 
bony scales. The skull and framework of the head is cartilagi- 
nous or gristly, well protected by external bony armour ; the 
entire skeleton also is gristly, and the vertebral column is 
prolonged so as to support the upper and longer lobe of the 
caudal fin. 
The snout projects far beyond the mouth, which is very 
small relatively to the size of the fish, toothless, transverse, 
with thick lips capable of protrusion like a short trunk. Be- 
tween the tip of the snout and the mouth hang four fleshy 
barbules or wattles, arranged in a straight transverse row. The 
arrangement of the fins corresponds to that usual in Teleostean 
fishes, subject, however, to some modification in position. Thus 
the dorsal is set very far back, close to the tail fin, the anal fin 
being opposite but slightly in rear of the dorsal. The pectoral 
fins are set low, at the side of the throat, and are long and 
powerful ; the ventral fins are placed far back, just in front 
of the vent. 
The Sturgeons are built on a scale suggestive of destructive 
habits and formidable rapacity ; but there exist, in truth, no 
more inoffensive creatures. Like that of the whales, the diet 
of the sturgeon consists of lowly organisms which nobody 
misses, and the fish is incapable of inflicting injury on man. 
