Primitive Whales. 43 
Zeuglodontide. These Primitive Whales have long skulls, with an 
elongated muzzle, broad forehead, the nasal opening placed about 
the middle of the length and roofed over by the nasal bones, 
and the brain-case relatively small. The bones of the internal ear 
and the position of the eye are essentially Whale-like, as is also the 
lower jaw of the Upper Eocene species, which has a long alveolar 
canal, a long and loose union of its two halves in front, and a 
distinct coronoid process. The teeth, which are coated with 
enamel, are simply conical as far back as the canine or first pre- 
molar, and are separated from one another by gaps up to the 
second premolar; but those further back are in contact, and have 
either two or three roots and triangular crowns, which are much 
compressed and strongly serrated. The normal dental formula 
WIG ove 
Three Molar Teeth of a Shark-toothed Dolphin. Half natural size. 
is I. 3, C.+, Pm. 4, M. 332, or the same as that of primitive 
carnivorous land Mammals. 
All the seven vertebrae of the neck are free; and the first 
twelve rib-bearing vertebiee are very like those of land Carnivora, 
eleven of the fifteen ribs carrying two heads. The fore-limb— 
and especially the scapula or shoulder-blade—has a generally 
Whale-like character, the bones of the upper arm and fore-arm 
being distinctly flattened, and thus suggesting that the limb had 
the character of a flipper or paddle. The articular surfaces of the 
limb-bones are, however, much better developed than in modern 
Whales. No traces of hind-limbs have been detected. In some 
species the body appears to haye been protected by an armour of 
bony plates. 
