602 The Amerwan Naturalist. (July, 
The species of this family belong to the genus Zeuglodon? Owen, 
although when the Z. drach hyspondylus Müll. is better known it 
may be found to be referable to a distinct genus, Doryodon Gibbes. 
The longer known Z. cetoides Ow. is distinguished by many pecu- 
liarities. Its skull presents a long symphysis of both premaxil- 
lary and mandibular bones. The cervical and dorsal vertebrae 
are of similar and medium length, while those of the lumbar 
region are remarkably elongate. The fore-limb was short, and 
in its cubital region quite narrow (teste Müller). The enamel of 
the teeth is wrinkled, and the posterior two-rooted teeth have 
coarsely serrate cutting edges fore and aft. The animal could not 
have been less than seventy feet in length. Bones of species of 
Zeuglodon have been found in the Upper Eocene of Arkansas 
and the Gulf States (in the White Limestone of Alabama), and 
of England and Egypt. It is also recorded as occurring in the 
Miocene of Malta. 
II. ODONTOCETI. 
This group is the most numerously represented by species, re- 
‘cent and extinct. The families differ as follows: 
I. Teeth of two types, one and two-rooted. 
Neck longer; teeth in both jaws; Squalodontide. 
II. Teeth uniformly one-rooted, 
a, Ribs nearly all two-headed. 
Teeth in both jaws; neck generally longer; Platanistide.. 
Teeth in lower jaw only; neck short; Physeteride. 
aa, Four or five anterior ribs only two-headed. 
Teeth in both jaws; neck short; Delphinide. 
The SQUALODONTIDE ae the ons in the form and 
character of their teeth, but the form of the skull is very different. 
They nevertheless, by their intermediate position, indicate the an- 
cestral relation of the Zeuglodontidz to the other Cetacea. But 
little is known of the skeleton of the Squalodontide. The species 
occur in Miocene beds of North America and Europe. They did 
not attain such huge proportions as the Zeuglodons, and did not 
exceed thirty feet at the most. The genera known are two, as 
follows : 
2 Basilosaurus Harl. 
