CLASS V. PISCES: ORDER 1. SELACHIA. 
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in some it is rasp-like, in others studded with tubercles or spines, with which latter the tail is always 
armed. These fishes, some of Avhicli attain 
to enormous dimensions, are admirably 
adapted by their form for existing at the 
bottom of the water on beds of sand or 
mud. When disturbed they slide along in 
an undulatory manner, and with a slight 
motion of the pectoral fins. They defend 
themselves by lashing violently with the tail* 
They are very voracious, feeding on fishes 
and Crustacea, and upon shelled or naked 
mollusks. Their teeth are flattened and 
lozenge-shaped, forming a serried phalanx 
of points directed backward. So powerful 
are the jaws that they are capable of crush- 
ing the shell of a crab with the greatest ease. The females exceed the males in size, as in the 
sharks : their eggs are corneous, and closely resemble those of the dog-fish. There are many 
species distributed over nearly all seas. 
Genus TORPEDO : Torpedo. — To this belongs the Electric Ray, T. vulgaris, called Cramp- 
Fish in England ; it is of considerable size, weighing from one to two hundred pounds. It is 
remarkable for an electrical battery situated between the pectorals and head and gills ; this is 
indicated by two elevations extending along the back, and consists of numerous cells formed like 
honeycomb, this being, as is the similar provision of the Gymnoius or Electric Eel, amply supplied 
with nerves. On being touched the animal imparts a severe electric shock, sufficient to stun 
its prey. It is found in the European waters, and probably also on this side of the Atlantic. 
There are about twenty species of this curious family in different parts of the world, and all sup- 
posed to possess electrical powers. It is said that one species is found on our coasts. 
THE ELECTRIC RAY. 
THE BORDERED RAT. 
THE SKATE. 
Genus RAIA : Raia. — This incudes the True Rays, of which there are several species which 
feed on fishes, mollusca, and Crustacea. The Bordered Ray, R. marginata, is two to three feet 
long, including the tail. The flesh is tolerably good; common on European coasts. Other 
species are the Homelyn or Spotted Ray, R. maculata ; Small-eyed Ray, R. microcellata ; 
