XXVIII PREFACE. 



Smithsonian Museum Catalogues. Each 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 iViV* 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 ViV* 



The column of "original numbers" embraces those attached 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, 1 divided either into lines 

 or twelfths, or into lOOths. 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 vertebrae ; the animal 

 usually with the head, body, and tail extended into the 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 to the 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 pcdustris, Putorius nigripes, Arctomys 

 pruinosus, Thomomya talpoides ? Arvicola borealis, drummondii, richardsonii, and xanthognathus , 

 and some others. 



' The English inch u.cd i. about equal to 11.26 French line., .9383 French inches, or to 25.40 millimetres. On the other 

 ,ch ,nch i. equal to 1.0657 English inches ; the French line to .0888 English inches, and the millimetre to .03937 

 English inche*. The French metrt is equivalent to 39.37 English inches, or 3.28 feet. 



