XIII 



PHYLUM CHORDATA 



571 



of this organ reaches its extreme limit in the ruminant Ungulata 

 and in the Cetacea. In a typical Ruminant (Fig. 1198, E, Fig. 

 1199), such as a sheep or an Ox, the stomach is divided into four 

 chambers the rumen or paunch, the reticulum, the psalterium, 



C 



De 



IL 



FIG. 1198. Different forms of the stomach in Mammals. A, Dog; -B, Mus decumanus ; 

 (', Mus musculus ; J), "Weasel ; E, scheme of the ruminant stomach, the arrow with 

 the dotted line showing the course taken by the food ; F, human stomach ; G, Camel ; 

 //, Echidna aculeata ; /, Bradypus tridactylus. A. (in E and (?) abomasum ; Ca. 

 cardiac end ; Cma, greater curvature ; Omi, lesser curvature ; Du. duodenum ; MB, csecum ; 

 0, psalterium ; Oe. oesophagus ; P. pylorus ; R. (to the right in Fig. E) rumen ; R (to the left 

 in Pig. E) reticulum ; Sc. cardiac division ; Sj>, pyloric division ; W. Z, water-cells. (From 

 Wiedersheim's Comparative Anatomy.) 



and the abomasum, or rennet-stomach. The first of these (Fig. 

 1199, V) is much larger than the rest; its mucous membrane 

 is beset with numerous short villi. The reticulum (c), which 

 is much smaller than the rumen, has its mucous membrane 



