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 manyplies, and abomasum 



FIG. 67. DIAGRAM 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; K, esophagus; ps, psalter- 

 ium; rt, 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 caecum is 

 absent. 



The lowest mammals, the Monotremata, resemble birds 



