160 ZOOLOGY. 



CLASS IV. 

 Pisces. FISHES. 



JD ISHES with but few exceptions, constantly reside In 

 water ; they breathe by the means of Gills, and swim by the 

 assistance of Fins ; their bodies are mostly covered with 

 cartilaginous plates or scales ; they are all destitute of Feet, 

 are cold blooded, and though capable of breathing through 

 their gills, this function does not appear of the same impor- 

 tance, as it is to most of the preceding tribes • seeming rather 

 accessary than positively requisite, from the great length of 

 time between their inspirations, and the slow circulation of 

 their blood^(which by the way, is we believe, constantly in the 

 same ratio as the power of elaborating air in the respirative 

 organs;) their motions through the water are facilitated and 

 regulated by their fins, of which the Caudal or ta.\\ fin, serves 

 to propel them forward ; (in all genuine fishes the tail is 

 placed vertically, whilst in the Animals of the order Cete, it is 

 constantly flat or horizontal ;) the Dorsal and Anal fins 

 assist to steer them laterally ; the Pectoral, to elevate or 

 depress them in the water, and when stationary, or at rest, 

 they are sustained by the Ventral fins ; many kinds are fur- 

 ther aided, in raising or depressing themselves by the con- 

 traction or dilatation of the Air Bladder ; they are all fur- 



