rable controversy over the correct usage of the
terms dolphin and porpoise. As mentioned in the preceding section,
common names of any species may vary from locale to locale and even from
individual to individual. Some persons argue for the use of the term
porpoise for all small cetaceans. Others insist on the term dolphin.
Still others either randomly use the terms or call members of the family
Delphinidae dolphins and members of the family Phocoenidae porpoises.
The evidence supporting any one of these positions is confusing at best
and no usage of terms appears to be without problems. We see no wholly
satisfactory resolution to the problem at this time. For all these
reasons, we have little desire to defend our decision to follow the last
of these practices in this guide, referring to all members of the family
Delphinidae for which the term dolphin or porpoise appears in the common
name as dolphins, and to the one member of the family Phocoenidae
represented in the western North Atlantic, _Phocoena phocoena_, as the
harbor porpoise. Although all cetaceans may be regarded as whales, the
term "whale" most commonly applies to the larger animals. For all
species treated, other common names by which they may be known are also
listed.

Detailed treatment of the relative merits of the various terminologies
is inappropriate here. Furthermore, it is our opinion that the usage of
the terms dolphin, porpoise, and whale as part of the common names of
cetaceans is largely a matter of personal preference.

ORGANIZATION OF THE GUIDE

The differences between baleen and toothed whales are easy enough to see
in animals washed up on the beach or maintained in a tank at a zoo or
aquarium. But since an animal at sea can seldom be examined that
closely, its most obvious characteristics may be its overall size, the
presence or absence of a dorsal fin, its prominent coloration or
markings, its general behavior, or its swimming, blowing, and diving
characteristics. For that reason, regardless of their scientific
relationships, all the whales, dolphins, and the one porpoise covered in
the main text of this guide are divided into three groups. Those over 40
feet (12.2 m) long are discussed in the section on Large Whales, those
from 13 to 40 feet (4.0 to 12.2 m) in the Medium-Sized Whale, and those
less than 13 feet (4.0 m) in the Small Whales, Dolphins, and Porpoise
(with a dorsal fin). There are no small whales, dolphins, or porpoises
in