OF THE INTESTINES. 
53 
stead of an os hyoides^ composed of several pieces, we 
find a simple cartilaginons film attached to the internal 
surface of the general integuments of the gular region, of 
which the two ends are prolonged far hack. This carti- 
lage is sometimes, as in the Boa, intimately united to the 
muscles of the throat, the fibres of which it divides, its 
posterior extremity being attached afterwards to the skin 
on the sides of the neck ; hut in the greatest number of 
other Ophidians, 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 Helm ANN Ueher den Tastsinn der Sehlangen. 
t For a description of the organs of digestion, see the Memoirs of 
Duvernoy, Ann, de Sciences Nat. ,* and Meckel, Vergl. Afiatom. 
