8 INTRODUCTION. 
In Europe, no remains of mammals have been detected in the cretaceous series, 
but in this country several vertebrae have been found in the Green Sand of New 
Jersey, associated with bones of the Mososawrus, which I have referred to two 
species of cetacea, under the names of Priscodelphinus grandevus and Priscodel- 
phinus Harlani.* 
The tertiary geological period is remarkable for the great number of mammals 
which 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 paleeontological 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, GipBES: Journ. Ac. Nat. Sc., 1847, I. 5. 
Zeuglodon cetoides, Owen: Trans. Geol. Soc., 1841, VI. 69. 
Zeuglodon macrospondylus, Miiller: Fos. Res. d. Zeug., 1849. 
BASILOSAURUS SERRATUS, Gibbes: Journ. Ac. Nat. Sc., 1847, I. 5. 
Zeuglodon brachyspondylus, Miiller: Fos. Res. d. Zeug., 1849. 
BASILOSAURUS PYGMAUS ? 
Zeuglodon pygmxus? Miiller: 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: 
PontogEnrus priscus? Leidy: Proc. Ac. Nat. Sc., 1852, VI. 52. (This may belong to the Basilo- 
SAUTUS PYGMLUS. ) 
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 :-— 
Proca Wyant, Leidy. Wyman: Am. Journ. Se., 1850, X. 229. 
Puocopon, Agassiz. Wyman: Ibid., 56. 
Detpuinus CALveRTENSIS, Harlan: Proc. Nat. Inst. Washington, 1842, IT. 195. 
Detpninus Conrandt, Leidy: Proc. Ac. Nat. Se., 1852, VI. 835; Wyman: Am. Journ. Sc., 1850, X. 231. 
BALHNA PALMHATLANTICA, Leidy: Proc. Ac. Nat. Sce., 1851, V. 308. 
BaLana 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. 
4 Proc. Ac. Nat. Sc., 1851, V. 327. 
