XVlll SYSTEMATIC INDEX* 



6. Snake tribe. Have plates on the belly, and scales on the 



tail page 224 



Viper, or Adder 225 I Hooded Snake 226 



Commom Snake 226 | Whip Snake 227 



CLASS IV. FISHES. 



The Fishes are all inhabitants of the water. They 

 breathe by means of gills ; and their organs of motion are 

 called fins. Their bodies are generally covered with 

 scales. Most of them have in their body an air-bladder, 

 which is of use in their rising or sinking in the water. 



They are divided into six orders. 



ORDER I. APODAL FISH. 



These have bony gills; and no ventral fins. 



1. Eel tribe. Have the aperture of their gills at the sides 



of the thorax ; and the body round, smooth, and slimy . . 227 



Common Eel 228 | Conger Eel 228 



2. Gymnotus tribe. -Have no dorsal fin, and the body eel- 



shaped, but somewhat compressed 229 



Electric Gymnotus or Eel ib, 



3. Wolf-Jish tribe.' Have the head rounded and blunt ; and 



the teeth extremely large and rounded 230 



Ravenous Wolf-fish ib. 



4. Sword-fish tribe Have the upper jaw long, hard, and 



sword-shaped 231 



European Sword-fish 16. 



ORDER II. JUGULAR FISH. 



These have bony gills ; and the ventral fins situated in front of 

 the pectoral fins. 



5. Cod Jri&e.Have the pectoral fins slender, and tapering to 



a point 232 



Common Cod 232 I Hake 236 



Haddock 234 Ling ib. 



Whiting 235 Burbot 237 



Pollack il. | 



