THE ANGLER-NATURALIST. 



By an enlargement of the anterior*, or more forward, end 

 of the nervous axis, the brain is formed, with which the 

 nerves of smell, sight, taste, and hearing are connected. 



Immediately under the spinal column, and divided from 

 each other by thin membranes, are situated the organs of 

 respiration, circulation, digestion, excretion, and also, when 

 it exists, the air- or swim-bladder f. This type of struc- 

 ture is common to all vertebrate animals ; but the peculiar 

 attribute of Fishes is, that in them the function of respira- 

 tion, or oxygenation of the blood, is performed through 

 the medium of water, not merely temporarily, but during 

 the continuance of life. 



Breathing-apparatus. 



For this purpose they have, on each side of the neck, gills 

 (branchiae J), consisting of arches of bone, to which the 

 filaments, or, spongy portions, of the gills are attached, and 

 which have their surfaces covered by a tissue of innume- 

 rable blood-vessels. There are five of these branchial, or 

 gill-, arches in fish, of which four support gills, the fifth 

 being appropriated to the ( dentiferous pharyngeal arch/ a 

 bony arch in the throat, bearing teeth. In breathing, 

 the water is taken in at the mouth, and, after passing 

 through the gills, is allowed to escape behind by the gill- 

 openings. In its passage through the gills and gill-fila- 



* Anterior used to signify the part nearest the nose of a fish, 

 which is sometimes also named proximal, the Latin for ' nearest.' 

 t Sometimes called the 'hydrostatic organ.' \ Latin for 'gills.' 



