OF THE INTESTINES. 53 



stead of an os hyoides^ composed of several pieces, \vc 

 find a simple cartilaginous film attached to the intenud 

 surface of the general integuments of the gular region, of 

 which the two ends are prolonged far back. This carti- 

 lage is sometimes, as in the Boa, intimately united to the 

 muscles of tlie throat, tlie fibres of which it divides, its 

 posterior extremity being attached afterwards to the skin 

 on the sides of the neck ; but in the greatest number of 

 other Opliidians, the horns, of the hyoid bone are free, 

 very approximate, and prolonged into the cavity of the 

 chest, sometimes even to the heart itself. Each of these 

 horns is accompanied by a cylindrical muscle of the same 

 extent united to their posterior ends ; these muscles, the 

 antagonists of the genio-hyoids, retract the tongue within 

 the sheath. The tongue, by its construction, is a true organ 

 of touch, and can neither serve as an organ of taste, nor 

 participate in deglutition, since it remains within its sheath 

 during that operation. A small aperture at the point of 

 the muzzle with which most serpents, except the water- 

 snakes, are provided, serves as an opening by which these 

 animals can dart out the tongue without opening their 

 mouths ; this is generally performed slowly, and it is only 

 when they are enraged that they dart out the tongue with 

 velocity.* 



OF THE INTESTINES. 



The alimentary canal of Ophidians t is remarkable for 

 its great simplicity. The oesophagus and the stomach, 

 forming but one continuous canal, it is impossible to as- 

 sign precise limits to each of these organs. The canal 

 descends quite straight behind the heart, and insensibly 

 enlarging it terminates in a pouch more or less capa- 

 cious ; turning afterwards to the right, it abruptly con- 

 tracts to form, as it narrows, a little sac, at the termination 

 of which is the valve of the pylorus, more or less distinct ac- 

 cording to the species. The intestinal canal usually oc- 



^ See Helmann Ueberden Tastsinn der Sehlangen. 

 t For a description of the organs of digestion, see the Memoirs of 

 DuvERNOY, Ann, de Sciences Nat. ; and Meckel, Vergl. Anatom. 



