96 STRUCTURE OF SERPENTS. 
their ribs are also very numerous ; and they are able to crawl 
upon the points of these, using them almost as Centipedes do 
their legs (fig. 42). But in general the movement of their 
Fig. 84.--ANATOMY OF A COLUBER 
bodies is accomplished by their being drawn-up into folds, ~ 
and then straightened so as to project the head. The pro- ~ 
longed form of the body in Serpents occasions a curious ~ 
variation in the arrangement of the principal organs, which — 
is shown in the accompanying figure. The esophagus orl} 
ul 
4 
‘ 
