74 AMPHIBIA. 



PLATE XX. 



THE SNAKE. 



(BOA CONSTRICTOR.) 



FIG. I. 



THE parts on the right side have been drawn outwards, to allow room for showing 

 the nerves. 



1. Three branches of the third trunk of the fifth issuing from the lower jaw ; two 



of them communicate with the ninth, as in 5 ; the other gives branches to 

 the membrane of the mouth as far as the sheath of the tongue. 



2. Hard portion of the seventh. 



3. Trunk of the par vagum. 



4. A nerve corresponding with that in 9, Fig. 2, Plate XVIII., derived from the 



ganglion of the sympathetic, and appearing to be the continuation of the 

 glosso-pharyngeal nerve : it terminates on the glottis and the muscles 

 attached to the anterior part of the jaw for drawing forward the irachea. 



gfe 



5. Ninth nerve, joined by a branch from the trunk of the par vagum ; it gives 



branches to the muscles of the tongue and fauces, one of which becomes 

 imbedded in the hyo-glossal muscle, and receives communicating branches 

 from the same nerve in its course to the tip of the tongue ; it communicates 



