t this time
is that the presentation may bring suggestions for improvement in the
arrangement of the kind of information presented here; an account along
similar lines for all of the kinds of mammals native to North America is
in prospect. Corrections of, and additions to, the material presented
here will be welcomed and I shall be especially grateful for suggestions
as to a more useful arrangement of the data.

In arranging the families, genera and species the aim has been, in each
category, to list the most primitive members first and to list last the
one which presents the highest total of specialization. The term _total
of specialization_ is used here, as Miller (1924:2) used it, to denote
the sum of the physical modifications which any mammal, or taxonomic
category of mammals, is supposed by the author to have undergone during
the course of its development away from its original or generalized
mammalian stock.

Subspecies of any one species are arranged alphabetically. On the maps,
of course, the subspecies are shown in their correct geographic
positions.

For each subspecies, or species if it has not been divided into
subspecies, there is given (1) the accepted scientific name (selected
in accordance with the rules of the International Commission of
Zoological Nomenclature); (2) a citation to the account in which the
terminal part of the name was first proposed (the original description
of zoological parlance) followed by a statement of the type locality;
(3) a citation to the account in which the combination of names
(generic, specific and subspecific) used in the present account first
was employed unless the name combination used here is the same as that
in the original description; (4) synonyms arranged in chronological
order, and (5) marginal record stations of occurrence.

These marginal records are arranged in clockwise order beginning with
the northernmost locality. If more than one of the marginal localities
lies on the line of latitude that is northernmost for a given kind of
mammal, the westernmost of these is recorded first. The marginal
localities that are represented by symbols on the corresponding
distribution map are in Roman type. Italic type is used for those
marginal localities that could not be represented by symbols on the map
because undue crowding, or overlapping, of the symbols would have
occurred. An understanding of how these localities are arranged and
knowledge as to which of these