DIVISIONS OF REPTILIA, 265 
articulation of the bodies of the vertebra, each of which is 
concave in front, and convex behind ( procelous), 
Of the other characters of the snakes, a few words may be 
said as to the tongue, the eye, and the teeth—all important 
structures in this order. The ¢ozgwe,in serpents, is probably 
more an organ of touch than of taste, and consists of two mus- 
cular cylinders, which are united towards their bases. The 
forked organ thus formed can be protruded and retracted at 
will, being in constant vibration when protruded, and being in 
Fig. 142.—The Maja Haje, a poisonous Snake of Egypt. 
great part concealed by a sheath when retracted. The eye of 
serpents (fig. 143, A) is not protected by any eyelids, and hence 
the peculiar stony and unwinking stare for which these reptiles 
are celebrated, In place of eyelids, the outer layer of the skin 
is prolonged over the eye as a continuous and transparent film, 
behind which is a chamber formed by the mucous covering of 
the eye, into which the tears are discharged. The outer mem- 
brane is periodically shed along with the rest of the external or 
epidermic layer of the integument, and is again renewed. The 
