126 ELEMENTS OF MAMMALIAN ANATOMY. 
long as the body. In man it is about nine times as long as 
the distance from the crown of the head to the coccyx. In 
Ruminants, such as the cow and the sheep, the stomach is 
very large and divided into four chambers—the rumen or 
paunch, reticulum, psalterium or manyplics, and abomasum 
ee - ramen | 
Fic. 67. DracrAM OF THE STOMACH OF A RUMINANT. 
a, Dotted line showing the direction of the food in the process of diges- 
tion; abom, abomasum; du, duodenum; @, esophagus; ps, psalter- 
ium; rf, reticulum. 
(Fig. 67). The rumen and reticulum serve as mere storage 
cavities, from which the food returns to the mouth for 
thorough mastication, and then passes direct, by means of 
a groove in the esophagus, into the psalterium, and finally 
on to the abomasum. The latter is the true stomach, and 
is provided with gastric glands. In the camels the rumen 
and reticulum have connected with them pouch-like diver- 
ticula for the storage of water. The constricted openings 
of the pouches into the rumen or reticulum may be entirely 
closed by sphincter muscles. 
In man and the higher apes there is present an attenuated 
extension of the caecum known as the vermiform appendix. 
In the fetus of man it is proportionally longer than in the 
adult. In the herbivorous mammals, such as the cow and 
rabbit, the caecum is greatly enlarged, so as to play an im- 
portant part in digestion. In a few forms, such as the 
sloths, some Cetacea, and a few Carnivora, the czecum is 
absent. 
The lowest mammals, the Monotremata, resemble birds 
