346 



ZOOLOGY 



SECT. 



becoming replaced, when worn out, by a successor developed on 

 its inner side. 



A bifid tongue like that of Lacerta occurs in several families of 

 Lacertilia. Others have a thick, short tongue, undivided in front 

 and often provided with two long appendages behind. The 

 Monitors (Fig. 1010, A) have forked retractile tongues like those 

 of Snakes. The tongue of the Chamseleons is an extremely 

 remarkable organ ; it is of sub-cylindrical form with an enlarged 

 extremity, and is so extensile that it is capable of being darted 

 out to a distance sometimes equalling, or even exceeding, the 

 length of the trunk ; this protrusion can be effected with lightning- 

 like rapidity ; and it is in this way that the animal catches the 

 Insects which constitute its food. The tongue in Snakes is slender 



I 



c 



B 



FIG. 1010. A, tongue of Monitor indicus. B, tongue of Emys europaea. C, tongue 

 S. ^"Sator. L, glottis ; M, mandible ; Z, tongue ; ZS, tongue-sheath. (From 

 Wiedersheim s Comparative Anatomy.) 



and bifid, capable of being retracted into a basal sheath, and 

 highly sensitive, being used chiefly as a tactile organ. The tongue 

 of the Crocodilia (C) is a thick, immobile mass extending between 

 the rami of the mandible. In some of the Chelonia (B) the tongue 

 is immobile ; in others it is protrusible, sometimes bifid. 



In the enteric canal of the Reptiles the principal special features 

 to be noticed are the muscular gizzard-like stomach of the Croco- 

 dilia, the presence of a rudimentary caecum at the junction of 

 small and large intestines in most Lacertilia and in the Ophidia, 

 and the presence of numerous large cornified papillee in the 

 oesophagus of the Turtles. 



Organs of Respiration. The Reptiles all have an elongated 

 trachea, the wall of which is supported by numerous cartilaginous 

 rings. The anterior part of this is dilated to form the larynx, 

 the wall of which is supported by certain special cartilages the 



