6 4 A BOOK OF WHALES 



We may now compare the complicated whale 

 stomach with the complicated Ruminant's stomach. 

 The latter, when typically developed, has the charac- 

 ters shown in the following description : The 

 oesophagus leads into a large paunch, the rumen ; 

 it equally leads into a smaller pouch, the reticulum ; 

 from this latter arises the psalterium, so called from 

 the leaf- like arrangement of its folds of mucous 

 membrane. Finally, there is the abomasum, the 

 truly digestive part of the stomach. In having 

 four compartments the stomach of a typical ruminant 

 agrees with that of the porpoise. But at this point 

 the agreement stops. The first three divisions of 

 the Ruminant's stomach are clothed with oesophageal 

 epithelium ; it is only the abomasum which is the truly 

 digestive part of the stomach. Thus in the Ruminant 

 the stomach may be regarded as being primarily 

 divided into two regions, the last of which only is 

 the digestive portion ; the first part is again sharply 

 marked off into three regions. In the Cetacea, on the 

 other hand, the stomach, although like that of the 

 Ruminant divided primarily into two parts, shows a 

 further subdivision of the digestive part which may 

 be exceedingly complicated in the Ziphioids, while 

 the non-digestive region is generally not divided at 

 all, and if it is (i.e., Monodon, etc.), the division is 

 not of so marked a character as in the Ruminants. 

 Even in the Manatee the stomach is more ruminant 

 than cetacean ; for the true digestive stomach, apart 

 from its two cseca, is not divided. Thus the stomach 

 of ruminant and cetacean have only this in common, 



