OLFACTORY APPARATUS. 807 



cranial plate of the ethmoid bone, which, from the number of apertures 

 that it offers for their passage into the nose, richly merits the name of 

 " cribriform," more especially in the carnivorous quadrupeds possessed 

 of the most acute smell. 



Fig. 406. 



Olfactory apparatus of the Lion. 



(2362.) The interior of the nasal cavity is divided by a median septum 

 into chambers, in each of which a very large surface is produced by 

 the complicated convolutions of the thin nasal plates of the ethmoid 

 (fig. 406, a), and of the inferior turbinated bone (>), over which the air 

 is made to pass in its progress to the lungs before it arrives at the 

 posterior nares (c). The whole of this complication of bony lamella is 

 covered with a delicate and highly-lubricated mucous membrane, wherein 

 the olfactory nerves terminate; and from the figure given, representing 

 the left nasal cavity of a Lion, some idea may be formed of the acuteness 

 of the sense in question conferred upon the predaceous Carnivora. 



(2363.) With this perfection of the olfactory sense a corresponding 

 mobility of the outer nostrils is permitted to the Mammiferous races. 

 In the Reptiles and Birds the external apertures leading to the nose 

 were merely immovable perforations in the horny or scaly covering of 

 the upper mandible ; but now the nostrils become surrounded with 

 moveable cartilages and appropriate muscles, adapted to dilate or con- 

 tract the passages leading to the nose, or even to perform more im- 

 portant and unexpected duties, as, for example, in the proboscis of the 

 Elephant. 



(2364.) The CETACEA, as regards the conformation of their nostrils, 

 and indeed of the whole of their nasal apparatus, form a remarkable 

 exception to the above description. Inhabiting the water as these crea- 

 tures do, they are compelled to breathe atmospheric air. Are they, 

 then, to smell through the intervention of an aquatic or aerial medium ? 



