INTRODUCTION. 
XV 
It may be remarked, that the last general work on the 
species of Mammalia, “ Fischer's Synopsis Mammalium” 
published in 1829 and 1830, contained 1126 which he 
considers well established, and 220 very doubtful spe- 
cies. Though the Museum collection nearly approaches 
these numbers, and is the largest assemblage of species 
hitherto brought together and arranged in one series, yet 
there are at least between 300 and 400 other species now 
known as existing in the different European collections, 
wanted to complete- the series, and many of these are in- 
habitants of our own possessions, or places with which 
we have considerable trade : it is therefore to be hoped 
that we shall soon be able greatly to reduce the number of 
our desiderata. 
British Museum, 
May-Day, 1843. 
JOHN EDWARD GRAY, 
