CiiAP. I. ORGANS OF SENSES. 277 



8o little developed. The cavity of the nose is wide, hut short. There are no 

 sinus frontales, nor lamina crihrosa, nor bony concha, nor even nasal bones.^ The 

 concha is cartilaginous. The nervus olfactorius is characterized by two tubercles at 

 its base, just in advance of the hemispheres; it has, in this respect, a strange simi- 

 larity with that of Frogs. The nostrils are always situated in the topmost part of 

 the snout; they seem particularly subservient to breathing, in water Turtles at least. 

 Thus I have frequently seen Trionyx ferox lying for lioin-s in shallow water, 

 buried in mud, and stretching only, from time to time, the nostrils above the 

 level of the water to breathe. The South-American Matamata is said to await 

 its prey in a similar situation, hid among the leaves of water plants, exhibiting 

 nothing above the water but the nostrils, which are elongated and tube-like, as 

 in Trionychida?. The marine Turtles also come from time to time to the surface 

 for the sake of breathing. 



The Tongue and Mouth. In all Ophidians and Saurians, as in most Birds, the 

 tongue is only an organ of touch ; in most of these animals it is long, slender, 

 covered with horn, and may be more or less protruded from the mouth for that 

 object. This is by no means so with the tongue of Turtles. It is broad, thick, 

 fleshy, generally folded, mucous, and in one family (the land Turtles) even thickly 

 provided with papillt^, like the tongue of a parrot. Turtles chew their food, partic- 

 ularly the herbivorous land Turtles, while other Reptiles swallow it without chew- 

 ing. Thus the organ of taste is very much developed. Not only the tongue, but 

 in some, as for instance in Trionyx, the whole pharynx is beautifully fringed 

 with fine, tree-like, branching papilla\'^ while in Chelonioidoe we find long, strong, 

 and hard papillae, extending even into the oesophagus. The papilla) of the latter 

 seem, however, from their hardness, more subservient to the motion of the food 

 than to tasting. But tasting is by no means the only function of the tongue. 

 Filling out the whole cavity of the mouth, it has also another function in the 

 process of breathing, as it has also in Frogs, for Turtles swallow the air they 

 breathe. (See, below, p. 281.) In all Turtles we find salivary glands. 



Organ of Touch. There is no special organ for this sense to l)e found in Turtles. 



' Comp. p. 30, respecting Ilydromedusa, wliitli - Coinp. Dr. A. Soger's Notes on the Anatomy of 



forms an exception, as it has nasal bones. the Gymnopus spinifer of Dum^ril and Bibron. 



