8 INTRODUCTION. 



In Europe, no remains of mammals have been detected in the cretaceous series, 

 but in this country several vertebra? have been found in the Green Sand of New 

 Jersey, associated with bones of the Mososaurus, which I have referred to two 

 siiecies of cetacea, under the names of Priscodelphinus grandcevus and Priscodel- 

 2ilnnus Earlani} 



The tertiary geological period is remarkable for the great number of mammals 

 Avhich have been ushered into existence in successive races, and in the same course 

 have become extinct. 



In Europe, the earliest tertiary or eocene formations have yielded an extraor- 

 dinary abundance of mammalian fossils, in which we have reason to feel a peculiar 

 interest, as, through the brilliant genius of Cuvier, they became the opening chapter 

 to the great volume of palasontological science. 



Until recently, in North America, the only mammalian genus which had been 

 detected as a member of the early Tertiary Period was the huge cetacean, the 

 Basilosaurus, Harlan, from the eocene deposits of Louisiana, Alabama, and South 

 Carolina. Of this genus several distinct species have been indicated as follow : — 



Basilosaurus cetoides, Gibbes : Journ. Ac. Nat. Sc, 1847, I. 5. 



Zewjlodon cetoides, Owen: Trans. Geol. Soc, 1841, VI. 69. 



Zevi/Iodon macrospondyhis, Muller: Fos. Ees. d. Zeug., 1849. 

 Basilosaukus serratus, Gibbes: Journ. Ac. Nat. Sc, 1847, I. 5. 



Zeiiglodon hrachyspondyhis, Muller: Fos. Res. d. Zeug., 1849. 

 Basilosaukus pygm^eus ? 



Zciujhdon pyf/maeus'! Muller: Fos. Res. d. Zeug., 1849. 



Quite lately, I referred a cervical vertebra found at Ouachita, Louisiana, to a new 

 genus of cetacean animals under the name : 



PoNTOGENEUS PRiscus ? Leidy : Proc. Ac. Nat. Sc, 1852, VI. 52. (This may belong to the Basilo- 

 saurus j^mmeeus.^ 



Very numerous remains of extinct mammalia have also been discovered in the 

 miocene and pliocene deposits of Europe, and likewise in those of the latter period 

 in the Sivalik Hills of the Himalayas of India, in South America, and Australia. 



The mammalia, which have been indicated as belonging to the Miocene Period 

 of North America, are as follow : — 



Phoca Wymani, Leidy. Wyman : Am. Journ. Sc, 1850, X. 229. 



Phocodon, Agassiz. Wyman: Ibid., 56. 



Delphinus Calvertensis, Harlan: Proc. Nat. Inst. "Washington, 1842, II. 195. 



Delphinus Conradi, Leidy: Proc. Ac. Nat. Sc, 1852, VI. 35; Wyman: Am. Journ. Sc, 1850, X. 231. 



Bal^na pal^atlantica, Leidy : Proc. Ac. Nat. Sc, 1851, V. 308. 



Bal^na prisca, Leidy : Ibid. 



In the pliocene deposits of this country the remains of extinct mammalia are 

 very numerous, and a large number of species have been determined as follow : — 



Cervus Americanus, Harlan : Fauna Amer., 1825, 245. 



Proc Ac. Nat. Sc, 1851, V. 327. 



