PHYSETERIDE 247 
yoked together.” This name was substituted by Owen for the 
earlier one Basilosaurus of Harlan, with the consent of that author, 
on the mammalian nature of the animal being demonstrated! The 
latter name is, however, still generally retained by American 
zoologists. The remains have hitherto been found chiefly in the 
Eocene formations of the States of Alabama, Louisiana, Mississippi, 
and Arkansas, and have been assigned to several species. A portion 
of a skull is recorded from the Barton Clay (Eocene) of Hampshire, 
England. 
Suborder ODONTOCETI, 
the DELPHINOIDEA, or Toothed Whales. 
Calcified teeth always present after birth; generally numerous, 
but sometimes a very limited number (in a few cases none) are 
functionally developed. No baleen. Upper surface of the skull 
more or less asymmetrical. Nasal bones in the form of nodules or 
flattened plates, applied closely to the frontals, and not forming 
any part of the roof to the narial passage, which is directed upwards 
and backwards. Olfactory organ rudimentary or absent. Hinder 
end of the maxilla expanded and covering the greater part of the 
orbital plate of the frontal bone. Lachrymal bone either inseparable 
from the jugal, or, when distinct, very large, and forming part of 
the roof of the orbit. Tympanic bone not ankylosed with the 
periotic, which is usually only attached to the rest of the skull by 
ligament. Rami of mandible nearly straight, much expanded in 
height posteriorly, with a wide funnel-shaped aperture to the dental 
canal, and coming in contact in front by a flat surface of variable 
length, but always constituting a true symphysis. Several of the 
anterior ribs with well-developed capitular processes, articulating 
with the bodies of the vertebre. Sternum almost always composed 
of several pieces, placed one behind the other, with which several 
pairs of ribs are always connected by the intervention of well- 
developed cartilaginous or ossified sternal ribs. External respiratory 
aperture single, the two nostrils uniting before they reach the 
surface, usually in the form of a transverse subcrescentic valvular 
aperture, situated on the top of the head. Manus always penta- 
dactylous, though the first and fifth digits are usually very little 
developed. No caecum, except in Platanista. 
Family PHYSETERIDA. 
No functional teeth in the upper jaw. Mandibular teeth various, 
often much reduced in number. Bones of the cranium raised so as 
1 See Trans. Geol. Soc. ser. 2, vol. vi. p. 67. 
