lson's "The Rabbits of North America"
(1909) published 27 and 42 years ago, respectively. These monographs are
still excellent sources of detailed information, as, of course, also is
Marcus Ward Lyon's "Classification of the Hares and their Allies"
(1904). The acquisition of additional study specimens in recent years,
however, has provided new data on the geographic occurrence of several
species, and study of these specimens has given basis for a different
arrangement of several named kinds of the lagomorphs. Two principal aims
of the present synopsis, therefore, are to combine in one publication
the current taxonomic arrangement and as much as is known of the
geographic distribution of the several species and subspecies.

The maps herewith and listings of marginal localities are the means
chosen to present the information on geographic distribution. The
artificial key is supplemented by line drawings of skulls of certain
species and by a minimum of text to aid the user of the key. The skulls
are necessary for the identification of some species of the genus
_Sylvilagus_. The skins, on the contrary, are essential for the
identification of the species of the genus _Lepus_ in central Mexico and
in the Great Basin of the western United States. Consequently, it has
been impossible to construct a key based on external characters only or
on cranial features only. Furthermore, the only apparent differences
between a given pair of species in one region may not be apparent in
another region where the same two species occur together. A case in
point is provided by _Sylvilagus floridanus_ and _Sylvilagus nuttallii_
where the Great Plains meet the eastern flank of the Rocky Mountains and
where the Sonoran desert meets the southwestern flank of these
mountains. The details are described by Hall and Kelson (1951:52, 53)
and are indicated in the part of the accompanying artificial key that
takes out the species _Sylvilagus nuttallii_. Because of this geographic
change in specific characters and because of the slight amount of
difference between certain species of leporids, I have frequently
resorted to geography, instead of to morphology alone, in constructing
the artificial key. Despite this fault of the key to the lagomorphs, it,
and the accompanying account, I hope, will aid workers who need to
identify kinds of lagomorphs and to know about their geographic
distribution.

Another reason for presenting a synopsis of the lagomorphs a