THE BLACK RAT. 
17 
and in the collection of this society, in the relative proportion 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 has the fore-feet of the same 
colour. 
“ The following is a comparison of this specimen with the M. rattus, as 
given by Mr. Jenyns. The same dimensions, with the very trivial difference 
of the ears being half a line less, appear in Mr. Bell’s British Quadrupeds. 
M. Hibernicus. M. Rattus. 
in. lines. in. lines. 
Length of the head and body . . . . .76.74 
head 1 10 . 1 It) 
• ears 0 9.0 11|- 
tail 5 6 . 7 11 
from the base of the ear to the snout . .16 
from the tarsal joint to the end of the toes 1 6 
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 M. Hibernicus. Should future investigation prove it 
to be a variety only of M. rattus, it can be so considered under the present ap- 
pellation.” 
The following information has been since obtained : — In March, 1838, 
Robert Langtry, Esq., informed me that, about fifteen or sixteen years 
previously, eighteen of these animals were killed, along with a great 
many common rats, during the “ taking-in of a stack ” of grain, at Fort 
William, near Belfast. There were three generations of them, viz. — two 
adults, several well grown, but apparently not mature, and a number of 
young ones. 
They were nearly all killed by himself, and neither before nor since 
were any seen about the place. He described the animals &o accurately, 
as to white breast, &c., that there is not a shadow of doubt relative to 
his correctness. The presence of three generations of this animal, in the 
same stack, with a great number of the Mils decumanus , speaks I think 
decisively against the latter species destroying them. 
Mr. Edward Benn, w T ho has frequently heard of the capture of black 
rats with white spots on their breasts, had it always described to him as 
being shorter in the tail than a second species of black rat, also described 
to him, and which was, perhaps, Mns rattus, a specimen of which, as 
already mentioned, he procured for me, in December, 1842. This gentle- 
man had learned that black rats with white spots on the breast were, at 
one time, not uncommon about a flour-mill at Carrickfergus. 
In August, 1843, I questioned the gamekeeper at Tollymore Park on 
the subject of this species, and he stated that he got a black rat there, 
about fourteen years before that date. It had a white breast ; its tail, 
he was certain, was shorter than that of the common rat ; and he felt sure 
that it could not have been a variety of the common species, for various 
reasons which he explained. 
Were there not a difference in form, I should bring this animal under 
Mus rattus, as a variety ; but, as those who have seen it all describe it to 
have a shorter tail than that species, I still retain it under the above pro- 
visional name. What is stated of this animal leads me to consider it as 
at least a permanent variety of Mus rattus. 
[Note. — The following memoranda were made by Mr. Thompson, after 
c 
