470 ANIMAL RESPIRATION 



really amphibious is rather difficult to say, for though it some- 

 times visits the sea, it does not of necessity follow that its gills 

 are then used for breathing air dissolved in water, though this 

 would seem probable. The division of each gill-chamber into two 

 distinct parts brings to mind the arrangement found in the amphi- 

 bious Apple- Snail (see p. 461). 



END OF VOL. II 



