THE BROWN OR COMMON RAT 619 



i6-4 to 22; diastema, 12 to 15-6; maxillary tooth-row, 6-8 to 8-8; 

 mandible, 26 to 33 ; mandibular tooth-row, 6-8 to 8-4. 



DistinguiBhing characters : — The Common Rat in all colour phases 

 is readily distinguishable from any sub-species of E. rattus by its 

 stouter build, greater weight (in relation to length of head and body), 

 shorter tail, shorter and thicker ears, and its larger hind feet. The 

 skull is characterised by its greater size and the peculiarities of form 

 in the parietal and interparietal regions described above. 



The Common or Brown Rat is probably the most injurious 

 and universal mammalian pest of the human race, and its 

 habits are so well known as not to require description ; or, 

 rather, they are so wide as to be comparable with those of man 

 himself, and would therefore require a volume for exhaustive 

 treatment. It does not appear to have a single redeeming 

 feature, its value as a scavenger being now negligible. 



Disregarding exceptional conditions, rats are wide-foraging 

 animals, dwelling in secure burrows,^ where they lie up in a 

 warm nest of grass or other materials, and to which they carry 

 their food, at least when abroad by daylight ; but probably 

 from reasons of prudence their forays take place chiefly at 

 night. Being powerful diggers, they are quick to construct 

 new burrows in the neighbourhood of food, and sometimes 

 these are merely temporary shelters, not occupied for purposes of 

 sleeping. The proximity of the food supply usually governs the 

 situation of the burrow, but there is no rule for its extent or 

 situation ; it generally consists of several winding galleries, and 

 possesses more than one entrance. The animals are apparently 

 loth to make unnecessary excavations, and they are quick to 

 burrow in heaps of soft material, such as manure (which is 

 also warm). For the same reason, perhaps, they are great 

 frequenters of ricks, ^ which also supply them with food ; of the 

 burrows of rabbits, where they devour the young ; and above 

 all of dwellings and outhouses, where they lie up in the floors, 

 walls, or more rarely, in the roofs (though common in thatch). 

 Their teeth are so powerful that they rapidly gnaw a way 

 through wooden partitions ; they have been known to damage 



' Sometimes at a distance from their food— see Field, 17th July 1886. 

 ^ Owen Jones records the capture of 600 rats from one rick, 1000 from two, and 

 1300 from three other ricks. 



