BOTANICAL 
GARDEN. J la | E , 
LETO 
THE 
AMERICAN NATURALIST 
Vor. XXIV. ^ JULY, 1890. 283. 
THE CETACEA. 
BY E. D. COPE. 
£o Cetacea, as the inhabitants of the water areas of the earth's 
surface, have had ample space for variation and multiplication 
of forms, an opportunity of which only a moderate advantage has 
been taken. The conditions have been more uniform than those 
to which lanc.mammals have been subject, and a corresponding 
uniformity prevails in this order. Owing to their habitat, op- 
portunities for their preservation have been better than in the case 
of animals of the land, and accordingly great deposits of their 
bones exist, notably on the east coast of the United States, and in - 
certain deposits of Belgium and Italy. Among the species 
brought to light in these localities, as among those now existing, 
we find examples of the most gigantic, not only of the Mammalia, 
but of the Vertebrata. The exising Balenoptera borealis reaches 
a length of over one hundred feet ; and several other species, in- 
cluding the sperm whale, attain to eighty feet. 
The order of Cetacea is one of those of whose origin we have 
no definite knowledge. It appears sparingly in the Zeuglodontidz 
in the Eocene period, and has its greatest multiplication in the 
ages of the Miocene. The Zeuglodontide are the most gen- 
eralized family, and forms intermediate between them and the 
modern Cetacea are found in Miocene beds. Modern types are, 
however, contemporaries of the latter, and these have achieved a 
multiplication of forms in Pliocene and modern times. 
