SOME INTERNAL STRUCTURES 61 



Beluga and the Narwhal have stomachs which 



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agree in many points with each other, and differ 

 slightly from the porpoise. Those whales, as will 

 be seen later, form a well-defined group of dolphins 

 contrasting in other points with the remaining 

 Delphinidae. In both of them the first division of 

 the stomach is strongly divided into two separate 

 chambers ; the minute third chamber of the porpoise 

 stomach, simply in that animal an excavation in the 

 thick wall of compartment II., is here larger, and 

 a distinct chamber visible before the stomach is 

 dissected. Finally, there is a fifth chamber, separated 

 off from the fourth, and, like it, of an elongated in- 

 testiniform shape. 



Of other dolphins, while Globicephalus and 

 Grampiis are most like Monodon, Orcella is most 

 like the common porpoise. So too are Platamsta 

 and Pontoporia. 



The stomach of Bal&noptera musculus, our ex- 

 ample of a whalebone whale, is constructed upon 

 the same plan as that of those dolphins that have 

 been already considered. It has four chambers like 

 that of the porpoise, but the proportions are a little 

 different. This will be observed from the accom- 

 panying figure. It will be noted that the second 

 chamber is larger than the first, and that the fourth 



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is relatively small. 



A still greater reduction is seen, according to Sir 

 William Turner, in the stomach of Balcena mysticetus, 

 at least in the foetus of that whale. The author 

 just mentioned counted but three chambers in its 



