22 THE STORY OF FISH LIFE. 



blood as in the higher fishes, and are divided by 

 the cavity through which a stream of water 

 is constantly passing for the aeration of the blood. 

 In the higher fish, as in the perch, for instance, 

 the septa or walls which constitute the pouches 

 have been dispensed with, and only a single slit 

 at the side of the head remains. 



In the sea-horses and pipe-fish the typical 

 gills are replaced by curious rosette-shaped tufts. 



The climbing perch (Anabas), serpent - heads 

 (Ophiocephalus), and some cat-fishes have curious 

 accessory structures enabling their owners to 

 quit the water for a more or less prolonged 

 sojourn on land. The accessory breathing-organs 

 of Anabas may serve as a type. If the outer 

 wall of the gill-chamber be removed, a cavity 

 will be exposed containing, below, the true gills, 

 and above a more or less rosette-like structure. 

 This rosette lies in a special air-chamber, and is 

 well supplied with blood-vessels for the aeration 

 of the blood whilst the fish is out of the water. 



Breathing by gills may be aided by breathing 

 through the skin, or breathing through the in- 

 testine, or by structures that correspond to our 

 lungs. 



Breathing through the skin or the intestine 

 may seem strange to many, but much of the 

 improbability that suggests itself at first will 

 disappear when we remember that " breathing " 

 is really the process of exchange of gases by the 

 blood. These gases can pass with the greatest 

 readiness through their membranes, such as the 

 skin, and so gain access to the blood almost as 

 easily as by the lungs. The common loach of 



