THE SNAIL-LIKE COCHLEA 



part of the ear inside, em- 

 bedded in bone. It consists of 

 three loop-hke canals and a 

 snail-Hke coil. All hairy mam- 

 mals have that snail-like con- 

 struction of the internal ear. 

 In Fig. 49 is photographed the fig. 48.— Drawing of 

 ear-bone of a mammal's skull ^l!TXn°a7eTof 

 cut through, and you can see ™^'^- A the coiled 



^ ^ tube known as the 



the place for the snail-like soft helix or cochlea. 



B the three tubu- 



ear — the cochlea or internal lar arches or semi- 



1 p ,1 -1 • n 1 circular canals. 



spiral 01 the ear, as it is called. 



No other animals except the mammals are 

 kno\vn to possess a spiral 

 internal ear, and all known 

 mammals do possess it. If, 

 therefore, you discovered a 

 fragment of bone showing 

 this spiral-like space you 

 would know that the bit of 

 bone must in all probability 



Fig. 49. ■ — Photograph . 



from a section belong to a mammal, 

 ^chtf LftTn^te^- At the beginning of the 

 nal ear is lodged, nineteenth century a portion 



showing the coils of 



the snail -shaped of a great elongated skull 



space in which the ^ ^ c * • 



spiral cochlea lies. was brought trom America 



75 



