SIRENIA AND CETACEA. 



317 



prolongation of the ethmoidal cartilage, wliich is so charac- 

 teristic of the majority of Cetaceans " (Huxley). The species 

 of Sqtialodon all belong to the Miocene and Pliocene Tertiary. 



Fig. 623. — Three of the lower moUirs oi Sqmdodon. Miocene Tertiary. (After Scilla.) 



The genus Saurocetes has been founded for the reception 

 of another Zeuglodont, in which there were double-fanged 

 teeth with conoid crowns. The remains on which this genus 

 are based are from strata of Tertiary age, near Buenos Ayres, 

 and they indicate an animal much smaller than the true 

 Zeuglodons. 



Lastly, it would appear probable that the genus Bcdmnodon, 

 founded upon teeth from the Eed Crag (Pliocene), is really 

 referable to this family, and probably to the genus Squalodon. 

 In part, however, teeth of Ziphioid Whales have also been 

 included under this title. By Owen, Balcenodon is regarded 

 as comprising teeth of a Cetacean nearly allied to the living 

 Sperm Whale. 



