402 



THE SENSORIAL FUNCTIONS. 



to furnish a still greater surface for the extension 

 of the olfactory membrane. In the Sheep, the 

 Goat, and the Deer, the structure is very similar 

 to that just described ; but the convolutions are 

 double, with an intermediate partition, so as to 

 resemble in its transverse section the capital of 

 an Ionic column.* They are shown at (t) in the 

 transverse section of the nostrils of a sheep in 

 Fig. 384. 



In carnivorous quadrupeds the structure of 

 these bones is still more intricate, and is cal- 

 culated to afford a far more extensive surface 



* In a species of Antelope described by Mr. Hodgson, cavities 

 exist, situated immediately behind the ordinary nostrils, and 

 communicating with them. These accessory nostrils are conjec- 

 tured to be useful to this exceedingly fleet animal by facilitating 

 its breathing, while it is exerting its utmost speed ; for the 

 expansion of the nostrils opens also these posterior cavities, the 

 sides of which, being elastic, remain dilated. Journal of the 

 Asiatic Society, Feb. 1832, p. 59. 



