ORGANS OF SMELL, TASTE, AND TOUCH. 157 



Organs of Smell. 



It is a very general character of the Reptilia, and is in rela- 

 tion to their peculiar mode of pulmonic respiration, that the pos- 

 terior nasal apertures perforate the palatal bones internally, this 

 being the case even in the Ichthyodea, though, however, some ge- 

 nera occur among these, in which, as in some Fishes, the nostrils 

 merely open as small slits behind the lips, as in Proteus and Siren, 

 while in Amphiuma, Menopoma, Acholotes, &c., the openings of the 

 choanae or posterior nares are found in the palate. The nasal 

 cavities are frequently lined by a plicated pituitary membrane, 

 e. g. in Proteus, as in Fishes. It is rarely, as in Trionyx among 

 the Chelonia, that the nose is lengthened out into a small mem- 

 brano-cartilaginous snout. The nasal canals are in other respects 

 very simple in the Naked and in the Squamigerous Reptilia ; in 

 the Batrachia the nostrils are contractile externally. A cartila- 

 ginous partition separates the two nasal passages, and cartilaginous 

 plates, invested by mucous membrane, and which correspond to 

 the turbinated bones, clothe the rest of the nasal parietes, and 

 project slightly beyond the bones, as cartilaginous external nasal 

 organs. The nasal passages are of greatest length in the Sauria, 

 as the Crocodile, and are frequently expanded in front, in the form 

 of a pouch, and, as in the Cetacea, can be closed by valves ; feebly 

 developed cartilaginous, or bony turbinated organs are also present. 

 Besides the olfactory nerves which pass through small ethmoidal 

 plates, and divide and ramify is a simple manner, a twig also from 

 the fifth pair of nerves is distributed chiefly to the external part of 

 the nose. A special nasal gland is found in many Serpents, con- 

 stantly situated between the superior maxillary, lacrymal, and 

 nasal bones, and having a proper excretory duct, that opens into 

 the palate. The Ccecilia and many Serpents have also an orifice 

 between the nose and eye, which leads into a small blind sac, from 

 which arises a small tentacle ; the function of this organ is un- 

 known. 



Organs of Taste and Touch. 



Although it is doubtful whether the members of the present class 

 are endowed with a distinct sense of taste, this is certainly not the 

 case with the Land Tortoises. Reptiles swallow their food nearly 



