160 ZOOLOGY. 



CLASS IV. 

 Pisces. FISHES. 



IF 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 Feei, 

 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 blood5(which by the way, is we believe, constantly in the 

 same ratio as the power of elaborating air iu the respirative 

 organs;) their motions through the water are facilitated and 

 regulated by their fins, of which the Caudal or tail fin, serves 

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

 placed vertically, whilst in the Animals of the order Cetc, 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- 



