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CHAPTEE XIX. 



OSSEI, OR BONY FISHES. 



UNDER this denomination is comprehended many of the fishes which 

 are most familiar to us. They are characterized, as we have said else- 

 where, as a group of animals having a solid skeleton. They are 

 divided into six orders ; founded, however, it is necessary to add, on 

 characteristics of little organic importance, and the names bestowed 

 upon them are of a most barbarous description. These names are, 

 I. PlectognatJii, namely, fishes in which the upper jaw is attached to 

 the cranium, from TrXe/cro?, interlaced, and <yvd6os, jaw. 



Afterwards those in which the upper jaw is movable, and the gills 

 arranged in circles, like rounded hoops. These are, II. the Loplw- 

 Irancliii, from A,o<o?, crested, or aigrette, and Ppdv^ia, gill. 



In the other orders the gills are arranged in a comb-like form. 

 These are divided into two great groups. In the first, the rays of the 

 fins are soft, except occasionally the first of dorsal or pectoral fins. 

 These are, III. the Malacopterygians, from pdXaKos, soft, and 

 Trrepvyiov, finned the third group of osseous fishes. In a later group 

 the fish have bony rays to the anterior dorsal fins, some osseous rays, 

 and the anal fin and generally one of the ventral fins. These are, 

 IV. the Acanthopterygians, from a/cav0a, spiny, and Trrepuyto/z, 

 finned, which form the last group of bony fishes. 



I. PLECTOGNATHI. 



From their organization the fishes of this order establish the passage 

 from cartilaginous to the osseous fishes. Their skeleton, which remains 



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