Listing of referenceshas been made specific whenever 
possible, in -the--beliefthat.such an-arrangenent,’ in a bibliog- 
raphy lacking extensive cross references, will prove the most 
convenient for the largest sney of users. Thus, such important 
subjects as breeding and reproduction carry only a few references, 
and physiology and similar subjects are not included in the clas- 
sification, Most titles that’might be included under these head- 
ings are listed under the designated fur animal in‘ the’ spécific 
references, a RE sine fy SOOT ED ee 
A fow eroups, notably rabbits, bears: and mountain lions, 
have reluctantly been excluded, ‘chiefly because of the extensive- 
ness of the litevature on rabbits and the unimportance of bears 
and lions as fur animals. Because of the availability of a good 
bibliography by Phillips, cited later in this Introduction, fur 
seals here are dealt with chiefly after 1925, which closes the 
date of title inclusion in Phillips! work. Few‘of the very large 
number of state papers, documents and reports ‘én seals and fur 
otters are included.” These may be found in tHé’ Catalog of the 
Public Documents, also cited in this Introduction, Foreign 
species are excluded except’ Tor the introduced ‘chinchilla; and 
foreign references are not listed except whére they have a direct 
application to our native forms or report on North American. -: 
species introduced into other ‘lands, 
It has been necessary to choose between various types 
of material, and some borderline works have been kept or rejected 
more or less arbitrarily. The hundreds of popular articlés ‘on 
trapping and fur animals which have appearedin-outdoor and -agri- 
cultural magazines are in most instances omitted, although their 
