THE MOUSE TRIBE. 141 
- body (8 to 9 inches), and usually not exceeding that of the body alone. The colour 
of the upper-parts is usually greyish brown, while the under surface is white; but 
black varieties are often met with, which in Ireland have been regarded as indicat- 
ing a distinct species. 
The brown rat is a far more powerful animal than the black 
species, which has not a chance against its stronger rival, although 
curiously enough it is stated that on some ships the two kinds may be found 
living together. The following anecdote, related by the late Mr. Frank Buckland, 
illustrates in a striking manner the superior power and at the same time the 
extreme ferocity of the brown rat. “A London rat-catcher,” writes the narrator, 
“shut up together in a cage the result of his day’s work, consisting of several 
dozen rats, of both species, and put them away carefully for the night, their 
intended fate being to afford sport for his employer’s dogs the next morning. 
What was his astonishment when he came to fetch them, to find none but brown 
rats remaining! these cannibals having cruelly devoured all their sable brethren.” 
Rats are practically omnivorous in their diet, devouring every kind of human 
food with avidity, and inflicting untold damage on the hen-roost, the dove-cot, and 
the rabbit-warren. Their devastations to corn-ricks, or to grain stored in 
insufficiently protected granaries, are too well known to need more than passing 
mention. Not only will they, as in the instance recorded above, prey on their 
cousin the black rat, but they will likewise slay and devour members of their own 
kind which have been caught in traps or otherwise disabled. In robbing poultry- 
houses, it is a well-ascertained fact that rats will convey the eggs in an unbroken 
condition for considerable distances, although it is not yet ascertained how this 
difficult feat is accomplished. The partiality of these animals for fish is well 
known, but that they will occasionally catch young eels for themselves has been only 
recently discovered. Mr. Harting adds that snails—both land and fresh-water— 
also form a portion of their diet; while on the sea-coast they will eat prawns and 
other crustaceans. 
The prolific nature of the brown rat is little short of marvellous, and 
thoroughly accounts for its enormous numbers when in favourable situations. 
Habits. 
Several litters are produced annually, each of which generally contains from eight 
to ten, and sometimes as many as twelve or fourteen young; and a female rat will 
breed when only half-grown, although the number of its progeny is then but three 
or four at a birth. When these animals obtain access to small islands inhabited by 
sea-birds or rabbits, the abundant food soon leads to a prodigious increase in their 
numbers; but sooner or later they practically exterminate the indigenous 
inhabitants, and then have to seek a more precarious livelihood by preying upon 
the crustaceans and molluscs on the shores. Some years ago the number of rats 
in the slaughter-houses around Paris was so great, that as many as 2650 were 
killed in a single night, and over 16,000 within a month. 
Rats, impelled by scarcity of provisions, at times make migrations in large 
bodies—generally, or always during the night; and on such journeys they will 
not hesitate to plunge boldly into and swim over such rivers as may come in their 
way; and it is related that instances have occurred of their being suddenly 
hemmed in during such voyages by a rapid formation of ice. Some years ago the 
