142 VITAL FUNCTIONS. 



cess of respiration is performed by taking the water into 

 the mouth, and forcing it through the gills, which sepa- 

 rating their filaments, exposes every part to its action. 



423. In the cartilaginous fishes, or those which have 

 no bony frame, as the Lamprey, there is no operculum 

 provided for the escape of the water during respiration, 

 but instead of this, there are several apertures along the 

 sides of the neck, or throat, through which the fluid is 

 thrown. 



424. Respiration in the, Lamprey. In the Lamprey, 

 often called the Lamper-eel, which is one of the cartila- 

 ginous tribe, the organs of respiration are so constructed 

 as to be independent of the mouth in receiving the water. 

 In this fish there are seven external openings, fig. 90, on 



90. 



each side, leading into the same number of separate oval 

 bag-like appendages, situated horizontally, the innei 

 membrane of which has the structure of gills. Into 

 these openings the water is drawn by the action of cer- 

 tain muscles, and having performed its office, is again 

 ejected by the same orifices. 



425. Were it not for this curious and singular provision, 

 the Lamprey would be unable to enjoy its usual habit of 

 adhering by the suction of the mouth to a smooth stone, 

 or other solid, or grasping and sucking its food by which 

 it lives. 



ATMOSPHERIC RESPIRATION. 



426. Having thus described the respiratory organs in 

 several orders of inferior animals, we now come to those, 



What difference is there in the respiration of the cartilaginous and 

 bony fishes ? 



