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 ditierence 

 of the ears being half a line less, appear in Mr. Bell's British Quadrupeds. 



Length of the head and body .... 



head . . ... 



ears ...... 



tail 



from the base of the ear to the snout 



from the tarsal joint to the end of the toes 



M. Hibernicus. 



M. Rattus. 



in. 



lines. 



in. lines. 



. / 



6 . 



7 4 



1 



lu . 



1 10 



. 



9 . 



U Hi 



5 



6 . 



7 H 



. 1 



6 





1 



6 





These differences incline me to consider this animal distinct from M. rattits, 

 and, being unable to lind any species described with which it accords, I propose 

 to name it provisionally AI. Hibeimicus. 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 

 previotisly, eighteen of these animals were killed, along witli 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 so 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, Avith a great number of the 3Ius decuinaniis, speaks I think 

 decisively against the latter species destroying them. 



Mr. Edward Benn, Avho 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, 3Ins 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 wliich he explained. 



Were there not a difference inform, I should bring this animal under 

 3Iits 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 Mi/s rattus. 



[Note. — The following memoranda were made by Mr. Tliompson, after 



