ARMOUR-CLAD WHALES 313 



a transition from the former, in respect of tooth-characters, 

 to the modern dolphins and porpoises is afforded by Sauro- 

 delphis, of the Argentine Pliocene, in which the roots of the 

 teeth, although single, are elongated antero-posteriorly and 

 thus display clear evidence of their original duality. By 

 Dr. Abel, Saurodelphis is indeed regarded as occupying 

 the middle position between Squalodon and the modern 

 dolphins ; the porpoises being considered to form a side 

 branch which diverged from the main stem at an earlier 

 date than the appearance of the genus first named. 



In conclusion, it may be mentioned that modern investiga- 

 tions tend to connect the ancestral toothed whales with the 

 Carnivora, and in no wise support Sir William Flower's 

 favourite idea that these cetaceans trace their descent from 

 early ungulates. 



