The Structure of the Mammalian Csophagus. 15 
opening of the stomach. In Arctomys striated fibers are found 
right up to the cardia, but for a very short distance at the lower 
end of the cesophagus are mixed with smooth muscle. In Sciurus 
also there is a short distance at the lower end of the cesophagus in 
which smooth muscle is found. In Erethizon the outer layer of 
Surface 
cornification 
: i Stratum 
ca \ germinativum 
1 _L. muscularis 
MUCOSe 
Fic. 6. Transverse section of tunica mucosa of Lepus nutalli mallurus. 
< 180. 
muscle is striated to the cardia, but the inner layer has a thick lower 
sphincter composed of smooth fibres. In Muscardinus the striated 
fibres extend over onto the preventricular dilatation which, as is well 
known, contains fundus glands and is therefore to be regarded as a 
portion of the stomach. 
