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PHYLUM CHORD ATA : CLASS PISCES —FISHES 



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whose lower half is buried under the skin, and whose 



projecting spine or " pike " 

 is a formidable weapon. 

 There are two pairs of 

 paired fins, triangular in 

 shape. The pectorals are 

 attached just behind the 

 v/> MHlllk^ 1'^ gill-clefts, the much smaller 



pelvic fins in front of the 

 cloaca, ventrally. In the 

 male they are prolonged into 

 claspers. 



In the head region the 

 i./'^ >U* ~ > J.5 nostrils — blind sacs — are 



situated in front of the 

 mouth, ventrally, but have 

 no communication with it. 

 Each is partly shielded by a 

 small flap of skin. The eyes 

 are at the sides of the head, 

 tu S -3 b with the spiracles just behind 



Farther back the 



^ 1| other five gill-clefts open at 



S r^" •" either side. Between the 



^ oJq two spiracles, on the top of 



•^ •-- the head, are a pair of 



g |;^ minute openings leading 



S 2| down to the ears. The 



[2 "^S lateral line is well marked 



I. II and continued on to the 



^ ^^ head, where there are 



. ^1 numerous clusters 01 sensory 



^ ^"-^ pores. 



1^ Movement. — The body 

 ^^ is extremely muscular, the 

 parietal muscles being seg- 

 mented into myotomes with 

 fine connective tissue parti- 

 tions. The powerful swing 

 of the posterior part of the 

 body and the tail propels the animal through the water. 



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