MUS HIBERNICUS RESTORED TO THE BRITISH FAUNA. 203 
opportunity of either seeing or examining the animal. This 
individual differs from the M. rattus.... in the relative propor- 
tion of the tail to that of the head and body; in having shorter 
ears, and in their being better clothed with hair, as is the tail 
likewise; and in the fur of the body being of a softer texture. 
The difference in colour between the M. rattus and the present 
specimen is, that the latter exhibits a somewhat triangular 
spot of pure white extending about nine lines below the 
breast, and the fore feet being of the same colour..... These 
differences incline me to consider this animal distinct from 
M. rattus, and being unable to find any species described with 
which it accords, I propose to name it provisionally Mus 
hibernicus.” 
It is not a little remarkable that after the careful examination 
made by Thompson, as is evidenced by his published detailed 
account, that this excellent naturalist should have associated this 
animal with M. rattus, an error of judgment which is repeated in 
his ‘Natural History of Ireland’ (vol. iv. p. 16), published in 
1856, where it is obviously considered to be a mere variety of the 
Black Rat—an error perpetuated up to the date of issue of the 
second edition of Bell’s ‘ British Quadrupeds,’ where the animal 
is merely alluded to as a variety of M. rattus; and down to the 
present time, the primary fact of its colour being black seems 
to have exercised not only a misleading but a lasting influence 
on our naturalists. 
Since Thompson’s investigations M. hibernicus appears to 
have received practically no attention at the hands of zoologists ; 
at least, endeavours to procure further published observations 
on it have failed. Its discovery, however, in the Outer Hebrides 
has re-opened the question, and the writer has to express his 
obligations to the authors of this work for the opportunity 
afforded him of examining and reporting upon their specimens 
received in the flesh, as well as a series of skins furnished by 
their obliging correspondents. 
Before proceeding to the consideration of the true status 
of Mus hibernicus, it is desirable to institute a comparative 
examination of the British species of rats. This is con- 
veniently and sufficiently afforded by the following tabulated 
information :— 
R2 
