510 THE OCEAN WORLD. 



often of great size, and sucks them like a leech. It is taken by hook 

 and line, and speared by a sort of barbed harpoon, like the trident of 

 the mythological Neptune, which is thrown, javelin fashion, at the 

 animal when seen at the bottom of the water ; the flesh is fat and 

 delicate. In the twelfth century one of our kings, Henry I., surfeited 

 himself at Elbeuf by partaking too largely of the Lamprey. The 

 river-lamprey resembles the above in its general conformation, but 

 is much smaller, and differs in the armature of the mouth, having only 

 a single circular row of teeth. It is blackish above, silvery beneath, 

 and is common in the markets of London and Paris, being frequently 

 taken in the Seine. A smaller species, about ten inches in length, 

 never leaves the fresh waters. It resembles the last species in colour, 

 but its two dorsal fins are continuous ; it is found in most European 

 rivers and brooks. In some of the English rivers they are frequently 

 taken in the eel-pots, weighing two and three pounds. They frequent 

 stony bottoms, where they find small animals on which they feed. In 

 its larva state it was long considered to be a distinct species of Am- 

 moccetes ; it is now, however, ascertained that it only acquires its 

 perfect form at the end of its second or third year. 



II. SELACHIA. 



The Selachians include a great number of cartilaginous fishes, vary- 

 ing much in form, including the rays, dog-fish, skate, torpedo, hammer- 

 fish, sharks, and saw-fish ; they have pectoral and ventral fins. On 

 each side of the neck, on the lower surface, are five gill-openings, in 

 form of a slit to each gill. Many of the species have two Hlow-lioles 

 in the upper part of the head. The order is divided into Raiadse and 

 Squalidse. 



BAIAD^E. 



Of the KAIAD.E there are several genera, and many species. In 

 Cephaloptera the head is truncated, with large, lateral eyes. In 

 Myliobates it is projecting, the pectoral fins extending like wings. 

 In Trygon it is enclosed by the pectorals. In the Skate (Raia) the 

 body is rhomboidal, tail without spine, but two small dorsals near the 

 top. In the Torpedo the body is nearly round, the tail short and 

 fleshy, with two dorsals and a caudal fin. 



The White Ray, Raia latis (Fig. 349), reminds us of the lozenge 



