THE order Cetacea is one of peculiar interest, having many specialities of structure, and being sharply defined from all other groups, with no outlying or doubtful forms at present known. Being purely aquatic animals, and all of considerable size, their remains are more readily preserved than those of some other orders. None, however, have been met with in the well-explored deposits of the cretaceous seas, or indeed in any European strata (with the doubtful exception of the cervical vertebrae of Palceoceitts from Ely), earlier than the Miocene. Abundant remains are, however, found in various Miocene and Pliocene marine beds, notably at Antwerp, in many parts of France, Germany, especially the Vienna basin, Italy, and South Russia. They are also found, though in a less perfect condition, in the crags of the east of England. In the Eocene deposits of the eastern states of America, the strange and gigantic Zeuglodons occupy the place of the ordinary_Cetacea, which occur in the Miocene and later ages.