MAMMALIA. 



9 



taiuing the transverse processes. The cervical vertebrae are thin 

 and sometimes united in living species. The true Dolphin lias 

 forty-seven sharp, conical, crooked teeth in each ramus, and are 

 well represented in the Miocene. 



The order is confined to the Tertiary and Recent Periods. The 

 most numerous fossil relics (teeth and ear-bones) have been found 

 in the Red Crag, England, but evidently washed out of Eocene 

 strata. The Balcenidm appear in the Pliocene. 



No. 12. [177] Zeuglodon hydrarchlis, Carus. 



Skull (cast). This carnivorous whale typifies a distinct family, the only 

 one having teeth implanted by two roots. Its teeth were first described by 

 Scilla in 1747; in 1836 by Harlan under the name of Basilosmiriis and Squalo- 

 don ; and in 1839 by Owen, who first determined the mammalian and cetacean 

 nature of the animal. When full grown, it was probably seventy feet in 

 length. The slvuU is long and narrow; the nostril single and looking upward. 

 It was discovered in a marl deposit of the "Jackson epoch" (Middle Eocene) 

 in Claiborne, Alabama, and belongs to theTylerian Museum at Haarlem. 



Size, 35 X 13. 



No. 13. [176] Zeuglodon cetoides, Owen. 



Two Teeth (cast). The jaws of the Zevylodon 

 are armed with teeth of two kinds, set wide apart; 

 the anterior have subcompressed, conical, slightly 

 recurved, sharp, pointed crowns, and are implanted 

 by a single root; the posterior are larger, with more 

 compressed and longitudinally extended crowns, and 

 witli botli front and liind borders deeply notched or 

 serrated. The crown is contracted from side to side 

 in the middle of its base, so as to give its transverse 

 section an hour-glass form. The root of the pos 

 terior teeth has two fangs. The mode of succession 

 conforms to the general mammalian type more than 

 any existing carnivorous Cetacean : i. e. the decidu 

 ous tooth is displaced and succeeded vertically by a 

 second molar. Tliese fossil teeth, one anterior, the 

 other posterior, were found at the same locality <i.s 

 the preceding, and are now in the Anatomical Mu- 

 seum of Berlin. Size, 6x4. 



