AIR-BLADDER 



359 



The sclerotic of the eye may be ossified. The ventral muscle 

 of accommodation is present as usual ; but there projects besides, 

 to the back of the lens, a vascular process from the choroid fissure, 

 the characteristic campanula Halleri (Fig. 346). A very large solid 

 otolith usually occurs in the saculus of the ear, and smaller ones in 

 the utriculus and lagena (Eetzius [356]). 



The duct of the air-bladder, always dorsal except in some 



—r 



Section through epidermis and phosphorescent organ of Mom ins. (After Brauer.) </<<, 

 glandular cells which secrete the light-producing substance ; g, transparent gelatinous tissue ; 

 I, lens ; r, reflector ; pigment surrounds the organ except on the surface turned towards the 

 epidermis. 



Characinids (p. 225), is generally longer and has a much narrower 

 lumen than in the lower Teleostomes ; the lumen may become 

 reduced or disappear, and the air-bladder be quite cut off in the 

 adult from the alimentary canal — a fact which led authors to divide 

 the Teleostei into Physostomi with open, and Physoclisti with closed 

 pneumatic duct. 



The shape of the air-bladder undergoes all sorts of modifications : 

 in the Cyprinidae it is constricted into a small anterior and a larger 



