Respiration 



105 



laries into the epidermis. An extreme saccular enlargement of the 

 buccopharyngeal cavity increases the efficiency of buccal respira- 

 tion. Gulped air is prevented from escaping through the gill slits 

 by a modification of the gill covers" (Noble, 1931). 



Bridge (1904) and Rauther (1910) have described the various 

 types of air-breathing which occur in fishes. Their lists include rhe 



Fig. 15. Beach-skipping gobies Irom Siam. These fish do not enter 

 the water but skip about on mud beaches. They have vascular res- 

 piratory areas in and near their tails. 



skin; air bladder; expansions from the buccopharyngeal cavity; 

 labyrinthine organs contained in such cavities and mostly developed 

 from gill arches; lung-like growths from the pharyngeal cavity; 

 and vascular intestines aerated by bubbles taken in through the 

 mouth. There has been no uniformity in the development of such 

 organs in particular groups of fishes. They therefore appear to be 

 of independent origin. For example, the silurid fishes show three or 

 four different types of air-breathing organs. Carter & Beadle (1931) 



