CHORDATA 





lakes, brooks, rivers, seas, and oceans the world over. Some 

 the marine fishes are littoral, living near the shore; others are 

 pelagic, living near the surface in the open ocean ; and still othi 

 are deep-sea species, only exceptionally seen near tin- surface. 



Some are confined to the north temperate and Arctic w 

 some remain in the tropics; some migrate as the temperature of 

 the water changes with the seasons. In the tropics the littoral 

 or shore fishes are usually very brilliantly colored, particularly 

 those living amongst the corals and algae. Thus they resemble 

 their surroundings, and the bright colors and peculiar marking- 

 protect them from their enemies by rendering them less con- 

 spicuous. The pelagic fishes are generally a steel-blue above 

 and whitish beneath. In the deep sea the colors are dull, hut 

 many deep-sea fishes are provided with spots or patches which 

 give out a phosphorescent light, the only light in those regions. 

 and by means of this light the fishes apparently see, as they 

 have well-developed eyes. 



Owing to the large number of species of Teleostei, and the 

 fact that most people are more familiar with them than with 

 other fishes, we can merely note here some wmich have an 

 especial scientific, economic, or other interest. 



The true eels, belonging to the genus Anguilla. differ from 

 the typical fishes in having a greatly elongated, nearly cvlin- 

 drical body. The dorsal and the ventral fins are continuous 

 with the caudal fin. They are covered with small scales, and 

 swim with great velocity. The eels spawn in salt water, and 

 the very young are strikingly different from the adult, resem- 

 bling the more typical fishes. The females ascend rivers and 

 live there in the mud until they are ready to deposit their eggs ; 

 the males do not apparentlv go far from the sea. The conger 

 eels are without scales and entirely marine; they are about 

 twice the size of the common eel, and attain a length of nearly 

 two meters. Related to the eels is the murrv, with its formida- 

 ble sharp teeth ; it is found in the Mediterranean and the tropical 

 waters of America. 



The catfishes (Fig. 296), of which several species are found 

 in the United States, have a variable number of long, soft pro- 

 cesses, the barbels, attached to the jaws. The skin is entirely 

 without scales, either naked or with bony plates. They are 



