OUR BEST FEATURES 



begins as an out-pushing of the mouth cavity, of 

 which it thus appears to be only a speciaHzed 

 outgrowth for the detection and testing of food. 



olfartory 

 capsule 



otic ^ \i 

 capsule t^ 



spiracle 



Fig. 81. Dissection of Head of Shark, Seen from Above, to 



Show Relations of Olfactory Capsules to Brain, Eyes 



AND Internal Ears (Modified from Marshall and Hurst). 



The most essential parts of the nose are the 



olfactory sense organs and the olfactory nerve. 



The fibers of the latter are spread all over the 



olfactory membrane, from which, being collected 



into two great nerve cables (Fig. 81), they pass 



155 



