ALIMENTARY CANAL OF REPTILES. 



435 



295 



lining membrane retains the ciliated epithelium in most Batrachia. 

 In fig. 294, B shows the roof of the mouth of a Newt, of the 

 natural size and magnified : A shows the floor of the mouth with 

 the oesophagus, d, laid open from above, the stomach, e, and lungs, 

 f,f. a is the lower jaw, b the tongue, c the glottis. The currents 

 produced by the vibratile cilia are made visible by powdered 

 charcoal, and their course is indicated by the arrows, beginning at 

 the symphysis and extending to the cardiac end of the oesophagus. 

 The ciliary movement ' is remarkably vivid in the mouth of the 

 Serpent ; and in the Tortoise it endures for several days after death, 

 not ceasing till the parts are destroyed by putrefaction.' l Fig. 

 295 gives a magnified view of some of the ordinary nucleated 

 epithelial scales, a, b, c, and of some ciliated scales, d, e,f,g, 

 from the mouth of the Frog. 



The tongue, as an organ of taste in 

 Reptiles, has been noticed, p. 327. In 

 Newts it is usually small, as at b, fig. 

 294. In most tailless Batrachians it is 

 lartre: attached to the floor of the mouth, 

 a little behind the symphysis of the 

 mandible, with its free border directed 

 backward. 2 This part can be raised 

 and thrown out of the mouth by a 

 rotatory movement, as on a hinge, with 

 a certain elongation, equaling in some 

 Toads two thirds or more of the length 

 of the body. A glutinous saliva is 

 spread over the surface : both the pro- 

 trusile and retractile movements are executed with extreme 

 velocity, and thus the insect is seized and swallowed more 

 quickly than the eye can follow, when the Batrachian has 

 brought its mouth within the distance at which the tongue can 

 reach the fly. 



The hyoid being raised and the mandible depressed, the genio- 

 glossi, having their fixed point at the symphysis, raise and jerk 

 forward the free part of the tongue ; at the same instant the 

 tongue is narrowed and lengthened by the action of transverse 

 fibres in its substance : the return movements are due to the 

 hyoglossi, acting from the hyoid arch, while this is at the same 

 time depressed and retracted. In most Frogs the back part of 

 the tongue is bifurcate, fig. 350, a, or bilobed {Polypedates) : in 



1 ccxxxvin. vol. i. p. 631. 



2 In Heteroglossus the tongue is attached by a central pedicle. 



F F 2 



Nucleated and ciliated epithelial scales 

 mouth of Frog 



