SECTION YI. 



THE CLASS OF PISCES OR FISHES. 



SUB-SECTION I. 

 THE FISHES COISTSIDEBED AS A CLASS. 



FISHES are cold-blooded vertebrates which live exclu- 

 sively in the water, and respire by means of gills instead 

 of lungs.* 



The limbs corresponding to the locomotive members of 

 the higher vertebrates are comparatively little developed, 

 and are called fins. 



Those fins which correspond to the anterior locomotive 

 members of higher vertebrates are called pectorals, and 



FIG. 286. 



p, pectorals ; v, ventrals ; d, dorsal ; a, anal ; c, caudal. 



those which correspond to the posterior, ventrals. Besides 

 the pectorals and ventrals, there are other fins which are 

 vertical. Those upon the back are called dorsal, those be- 

 neath the tail anal, and the fin at the end of the tail caudal. 



*The Climbing Perch, of the East Indies, sometimes leaves the water, 

 and moves for considerable distances upon the land, and. in some cases, 

 even ascends the trunks of trees ! This fish has an apparatus under the gill- 

 covers by means of which water is retained and given up to the gills drop 

 by drop. 



