THE SNAIL-LIKE COCHLEA 



part of the ear inside, em- 

 bedded in bone. It consists of 

 three loop-hke canals and a 

 snail-like 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 

 cut through, and you can see 



ear-bone of a mammal's skull the auditory organ 



or internal ear ot 

 man. A the coiled 

 tube kno^vn as the 



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



B the three tubu- 



ear — the cochlea or mternal lar arches or semi- 

 spiral of the ear, as it is called. ^^^^^ ^^ ^^^^ ^' 

 No other animals except the mammals are 

 known 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 

 belong to a mammal. 



At the beginning of the 

 nai ear is lodged nineteenth century a portion 



showing the coils of ^ l 



the snail -shaped of a great elongated skull 



space in which the 



spiral cochlea lies. was brought from America 



75 



Fig. 49. — Photograph 

 from a section 

 through the bone in 

 which the soft inter- 



