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elongated muzzle. They ascend the large rivers room xi. 
to spawn, and furnish one of the most profitable 
fisheries. Their flesh is excellent; their roe, 
dried and salted, forms caviar, and their swim¬ 
ming bladder, merely washed and dried, isinglass. 
The Spatularige ( Polyodon ) have a free gill- 
flap, like the Sturgeons, but their beak is long 
and spatula-shaped, and their mouth large and 
armed with teeth. 
TheChimeras have great affinity to the Sharks, 
both in external form and the position of 
their fins, but their gill cavity opens externally 
by a single hole on each side, and is covered 
by the rudiments of a gill-flap. Between their 
eyes they have a fleshy process ending in a 
group of small spines. They lay very large 
eggs, with a coriaceous shell, of an ovate lance¬ 
olate shape. 
All the other cartilaginous fishes have their 
gills adherent to the outer side of the gill cavity, 
allowing the water to escape through a series of 
holes between each gill. 
In most of these, as the Sharks and Rays 
( Squalidce), the gills are laminar. The fish are 
furnished with large pectoral and ventral fins; 
and the mouth, which is usually placed under 
the end of the muzzle, is armed with teeth. 
The Sharks are distinguished by their elong¬ 
ated form and long tail, and by the gill aper¬ 
ture being placed on the side of the neck. 
Many 
