106 



NATURAL HI STOUT. 



enamel ; the malar bone is short and slender, generally reduced to a mere splint between the 

 maxillary and squamosal processes of the zygomatic arch ; the thumb is rudimentary, but often 

 furnished with a small nail ; and the tail is generally scaly, with a few scattered hairs, densely hairy 

 only in a few species. 



As might be expected in so lai'ge an assemblage of species, the variety of forms is very great 

 among the Muridse, but broadly, the common Rats and Mice, which are only too well known to 

 most of us, may serve as characteristic types of the whole series. The family, however, includes 

 jumping forms, swimming forms, arboreal forms, and burrowing forms, in which the peculiarities 

 of the life-habits are very distinctly indicated by the extei-nal appearance of the creatures. In 

 their distribution the Muridse are almost absolutely cosmopolitan, the family being represented in. 



BROWN RAT. 



every part of the world, with the sole exception of the islands of the Pacific Ocean. Australia 

 possesses about thirty species of the family. New Zealand, at the time of its discovery, harboured a 

 Rat, known as the Forest Rat, or Maori Rat, which was a favourite article of food with the natives, 

 and is now almost extinct. It was proved by Capt. Hutton to be identical with the Black Rat (Mus 

 rattus), and was probably introduced by the ancestors of the Maoris. Certain species also, such as 

 the common Brown Rat and Mouse, are now perfectly cosmopolitan in their distribution, having 

 accompanied man in all his migrations on the surface of the globe. 



The Rat and Mouse form the types of a great sub-family, MURIX.E, which have the molars rooted 

 and tuberculate when young, the infra-orbital opening high and perpendicular, widest above, and the lower 

 root of the zygomatic maxillary process flattened into a perpendicular plate. They possess no cheek- 

 pouches, have the fore and hind limbs approximately equal in length, the thumb rudimentary, and the 

 tail nearly naked, covered with scaly rings. The genus Mus, to which our household pests belong, 

 includes upwards of one hundred species, scattered over most parts of the Eastern Hemisphere, and 

 living sometimes chiefly in the neighbourhood of human habitations, granaries, &c., where they often 

 feed indifferently upon animal and vegetable substances, sometimes in the open country, and feeding 



