356 Coe and Kunkel— California Limbless Lizard. 
the bottom of eaeh of which one, two, or several short tubular 
glands extend to the rather thick muscularis mucose. In their basal 
portions the glands twist about considerably. 
The pyloric valve is remarkably highly developed, as described by 
Leydig (’72, p. 120) for Anguis. It consists of a muscular, circu- 
lar fold, fluted longitudinally and projecting into the lumen of the 
duodenum. 
The duodenum has a diameter nearly as great as that of the 
stomach, and except for the sharp bend at its anterior end is almost 
straight. Its mucous 
membrane is thrown up 
into very conspicuous 
tongue-shaped villi 
(text-fig. 6), which are 
oval insection and placed 
with their long axes 
transversely to the 
length of the canal, as 
is common in many va- 
Figure 3. Section of epithelium of duodenum, rieties of reptiles. The 
showing absence of glands. x 250. 
epithelium of the villus 
is, like that of the lining of the intervening intestinal surface, com- 
posed of simple columnar epithelium with thickly placed goblet cells 
(text-fig. 3). No other glands occur. The epithelial cells exhibit the 
peculiarly striated free border so characteristic of the small intestine 
of the higher vertebrates. Conspicuous blood and lymphatic ves- 
sels occupy the central portions of the villi. 
The duodenum passes imperceptibly into the ileum, there being no 
distinct line of demarcation either anatomically or histologically. 
The villi of the duodenum become gradually shorter and closer 
together, and eventually give place to irregular wavy folds which 
extend lengthwise throughout the ileum. The posterior end of the 
ileum, however, has a nearly smooth lining. Its posterior end is 
much narrower than the more anterior portions, and the change from 
ileum to large intestine is very marked; there is here a distinct 
annular constriction separating the two chambers (pl. xi, figs. 25, 
26, text-fig. 1). This valve is marked by strong circular muscles, 
and the mucosa is thrown up into marked longitudinal folds. There 
is no free fold of the mucosa, however, such as occurs between 
stomach and duodenum or between rectum and cloaca. 
The small intestine opens into the large intestine on one side of its 
central axis, so that an indication of a rudimentary cecum is formed 
