PISCES. 
330 
THE FIRST ORDER OF CHONDROPTERYGII,— 
CHONDROPTERYGII BRANCHIIS LIBERIS,— 
(Or, with free gills), have in their gills a single wide opening, and a gill-lid, like the Bony 
Fishes, but they have no gill-rays. There are two genera. 
Accipenser, the Sturgeon.— General form like that of the Shark, but the body more or less covered 
with bony plates in longitudinal rows, and the head externally armed with the same. Their mouth, 
placed under the muzzle, is small and toothless ; and the palatal bones, soldered to the maxillaries, 
form the upper jaw, while 
there are vestiges of the in- 
termaxillaries in the thick 
lips. Placed upon a pedicle 
of three articulations, this 
mouth is more protractile 
than that of the Shark ; 
the eyes and nostrils are on the sides of the head, and harbules are suspended from the muzzle ; the 
labyrinth within the cranial bones is perfect, but there is no external ear — the hole behind the temple 
leading merely to the gills. The dorsal is behind the ventrals, and has the anal directly opposite to it ; the 
caudal surrounds the extremity of the spine, and terminates in the upper lobe of the tail, but an under 
lobe gives the tail the appearance of being forked. Internally, we find the spiral intestinal valve, and 
the single pancreas of the Shark family ; and there is a very large air-bladder, which communicates 
with the gullet by a large opening. Sturgeons ascend some rivers in vast numbers, and are the object 
of valuable fisheries. The flesh of most is agreeable, their eggs or roes are made into caviar, and their 
air-bladders furnish the finest isinglass. 
Fig. 146. — The Sturgeon. 
A. sturio, the Common Sturgeon, occasionally found in the west of Europe and on the British shores, is about 
six feet long, has a pointed muzzle, five rows of plates with strong spines, and its flesh is much esteemed, being 
somewhat like veal. The rivers falling into the Black and Caspian Seas produce this and three other species, if not j; 
more. A. ruthenus, the Sterlet, is seldom more than two feet long, with the plates on the lateral line numerous and i 
keeled, and those in the belly flat. It is considered delicious, and caviar made from it is reserved for the li 
Russian court. There is reason to believe that this is the Slops and Accipenser so much celebrated by the ancients. ■ 
A. stelatus, the seroregia of the Russians, and the scherg of the Germans, grows to the length of four feet, has the | 
plaits rougher and the snout more slender than the others. It is very numerous, but less esteemed than the 
Common Sturgeon. A. huso, the Great Sturgeon, has blunter plates, a smoother skin, and shoi’ter snout and cirri, ; 
than the Common Sturgeon. It is frequently found more than twelve, or even fifteen, feet in length, and weighing i 
more than twelve hundred pounds. One specimen is mentioned which weighed near 3,000 pounds. Its flesh is not 
much esteemed, and it is sometimes unwholesome ; but its air-bladder yields the very finest isinglass. It is found j 
in the Po as well as in the northern rivers. |1 
Several Sturgeons are found in North America, which are peculiar to that quarter of the world. i 
Voliodon, may be considered as a subgenus of Accipenser. These fishes are distinguished by the great prolong- i 
ation of their snout, the broad margins of which give it the figure of a leaf. In the general form and fins they re- |i 
semble the Sturgeons ; but their gill-openings are wider, and the gill-lid is prolonged in a membranous flap, which n 
extends to half the length of the body ; their gape is much cleft, and furnished with a number of small teeth. j 
Their upper jaw is formed by the union of the palatals and maxillaries with a pedicle of two articulations. There is j 
a spinal cord like that in the Lamprey, and the same spiral valve which is common to most of the order ; but the j ■ 
pancreas is partially divided into coeca. They are furnished with an air-bladder. Only a single species is known, j ! 
P. folium, which is found in the Mississippi. j 
CMmcera. — This second genus of cartilaginous fishes with free gills, closely resembles the Sharks in \| 
form, and in the disposition of the fins; but the gills open externally by one apparent hole in 
each side, though, if we examine more closely, we find great part of their edges attached, and that there 
are five separate holes terminating in the common aperture : still they have a vestige of an operculum 
concealed in the skin. Their jaws are more reduced than in the Sharks, for the palatals and tempo- 
rals are mere simple vestiges suspended to the sides of the muzzle, and the upper jaw is represented by 
the vomer only : hard and undivided plates supply the place of teeth, four of them above, and two below. 
The muzzle, supported as in the Sharks, projects forwards, and has pores arranged in rows nearly 
