38 OEGANIZATIONOFREPTILES. 



but much shorter, and in such as have dilatable jaws, the two external nares seem 

 to form only one posterior opening, which enters near the mesial line.* 



The sense of smell is least perfect in the Batrachian animals; the anterior and 

 posterior nares being almost opposite each other, the latter opening just within 

 the border of the upper jaw; consequently the canals can be of but small extent. 

 The olfactory nerve detached from the olfactory lobe of the brain, does not subdi- 

 vide, as in the Mammalia, and pass through an ethmoid bone, but enters a single 

 nerve without ramification until it arrives at the pituitary membrane, where it 

 divides into large fibres and then terminates. As there are no extensive sinuses 

 and cells to arrest the odoriferous particles contained in the air, while it passes to 

 the lungs in respiration, it follows that the sense of smell must be less perfect — 

 nor is it in as constant operation as in the Mammalia, where it is placed as a 

 guard to determine the nature of the air respired. 



Taste. — All Reptiles have a tongue, varying however greatly, as we have seen, 

 in its shape, organization, and mode of attachment, but certainly having little 

 claim to be considered as an organ of taste; since it is not constituted to receive 

 delicate impressions, being often covered with a thick, and in some instances, with 

 a horny cuticle. Swallowing their prey rapidly, and without mastication, a delicate 

 sense of taste would be here useless in determining the nature of their food, and 

 it is probable that the sense is entirely wanting or at best but feebly developed, 

 in Reptiles. 



Organ of Touch. — There is a general sensibility no doubt in the whole surface 

 of the bodies of Reptiles, by means of which the animals may be made acquainted 

 with the presence of external objects; but this sense is not perfect enough to enable 

 them to distinguish the form or other properties of bodies that are made known 

 to the higher animals by a sense of touch. In the inferior animals this sense is 

 intimately connected with the nutritive organs, and is only sufficient to afford 



* Dumeril, Hist. Nat. des Rept., torn. i. p. 37. 



