ARMOUR-CLAD WHALES 313 
a transition from the former, in respect of tooth-characters, 
to the modern dolphins and porpoises is afforded by Sauro- 
delphzs, 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, Sauvodelphis is indeed regarded as occupying 
‘the middle position between Sgualodon 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. 
