SOME INTERNAL STRUCTURES 77 



in the Cetacean, Zeuglodon. An addition of great 

 weight has been made to these discoveries by Pro- 

 fessor Klikenthal, who found besides the fairly well- 

 developed rudiments of teeth very rudimentary traces 

 of a second dentition, thus showing that the whale- 

 bone whales, like their toothed allies, are diphyodont 

 like other mammals. Furthermore, he has given 

 reasons for believing that in them, as in the toothed 

 whales, it is the milk dentition which persisted longest, 

 as it is represented by the most fully developed rudi- 

 ments. 



THE BRAIN 



The brain of all whales presents a most unusual 

 shape of that organ. It is very much compressed 

 from before backwards, and is thus broader than it 

 is long. It looks almost as if these creatures, rush- 

 ing through the waves, had flattened their brains in 

 the effort to oppose the weight of water. But though 

 so much shortened and comparatively small in total 

 bulk, the cerebral hemispheres of the Cetacea make 

 up to some extent by the highly-developed convolu- 

 tions of the brain surface. It used to be held, and 

 the belief is often seen in popular books, i.e., books 

 which deal loosely with the facts and inferences of 

 science that the furrows of a brain corresponded 

 with its thoughtfulness ; that the higher the type the 

 more abundant those grooves and furrows upon the 

 surface, which separate the complicated system of 

 ridges of brain substance known as the convolutions. 

 It is, of course, perfectly true that the brain of the 



