XXVIII PREFACE. 
Smithsonian Museum Catalogues. ach class of animals has its separate catalogue and suc- 
cession of numbers, from 1 upwards, in this series, the same number being never used twice for 
different objects in its class, and thus constituting an essential part of the specimen. There is 
also a special catalogue of the osteological collections. Thus, the skin of a mammal will have 
one number, and its skull, if separated, another ; each specimen having both numbers attached, 
its own as numerator of a fraction. Thus, when a skin is labelled or entered ;42;5, it is to be 
understood that 421 is its number, as entered in the catalogue of skins (or entire specimens in 
alcohol,) while 1149 is the number of the skull, as entered in the osteological catalogue. The 
skull itself would in this case be marked 124°. 
The column of ‘‘ original numbers ’’ bos ciel those abienled to specimens in the field by 
collectors. These are always retained as being referred to in the field notes of the different 
parties. 
The measurements have, in all cases, been made in English inches,! divided either into lines 
or twelfths, or into 100ths. All the skulls, and in most cases the smaller skins, have been 
measured with dividers or callipers. The measurements of the body have been made to the 
insertion of the tail into the rump, or nearly to the very base of the caudal vertebre ; the animal 
usually with the head, body, and tail extended into oe same straight line, avoiding, as far as 
possible, all curvature. 
Where measurements are recorded as made before skinning, they are, in most cases, to be 
understood as having been furnished by the collector. 
For the sake of illustrating more fully the character of the species described in the present 
Report, I have prepared the three lists as follows: 
The first list is that of the higher groups characterized in the following pages. 
The second list contains all the species of mammals found in North America north of Mexico, 
that I have had an opportunity of examining, while preparing the present work, together with 
a few that belong tothe northern provinces of the last mentioned State. These are inserted, as 
very probably existing within the limits of the United States, even though not yet detected. The 
indications of geographical distribution are chiefly those furnished by the specimens before me, 
although I have occasionally given statements in this respect from Audubon, Bachman, and 
Richardson. I have not pretended to define, with critical accuracy, the complete range of the 
species, the facts on record not being sufficient for the purpose. 
The third list embraces the species which have not fallen under my notice. Some of these have 
little claim to a place in the fauna of North America north of Mexico, while others are, in all 
probability, the same as those mentioned in the first list. A few are unquestionably additional 
and good species ; especially such as Sorex fimbripes and palustris, Putorius nigripes, Arctomys 
pruinosus, Thomomys talpoides ? Arvicola borealis, drummondii, richardsonit, and «wanthognathus, 
and some others. 
1 The English inch used is about equal to 11.26 French lines, .9383 French inches, or to 25.40 millimetres. On the other 
hand, the French inch is equal to 1.0657 English inches ; the French line to .0888 English inches, and the millimetre to .03937 
English inches. The French metre is equivalent to 39.37 English inches, or 3.28 feet. 
