168 The Alligator and Its Allies 
few cells are seen sloughing off as in Figure 40; possi- 
bly the act of feeding keeps the superficial scaly 
cells rubbed off smooth. 
In the extreme posterior region of the roof of the 
mouth the epithelium consists of a greater number 
of layers (though the number is very variable) 
than in the region shown in Figure 4o. In this 
posterior region, as noted above, glands are found. 
These glands have the same structure as those 
described in connection with the posterior region of 
the tongue. 
The Ctsophagus. Sections of the cesophagus 
were made from two regions, an anterior, half-inch 
caudad to the pharnyx, and a posterior region, 
half-inch cephalad to the opening of the cesophagus 
into the stomach (Fig. 35). 
The general structure of the wall of the cesopha- 
gus, as seen under a low magnification, will first 
be described, after which the minute structure of 
the epithelium, as seen under high magnification, 
will be discussed. 
In the anterior region the usual layers of the 
vertebrate enteron are present, except, possibly, 
the muscularis mucosa. 
The epithelium, to be described later, is, together 
with the submucosa, thrown into complicated 
folds; its closely arranged and darkly stained nuclei 
cause it to stand out in strong contrast to the other 
tissues of the section (Fig. 41, ¢). 
The submucosa, sm, is of considerable thickness, 
