438 
MAMMALIA. 
but these form exceptions. The Rodents^ therefore, like all 
herbivorous animals, have the intestinal canal of great length. In 
the Guinea-pig it measures nearly 10 feet ; in the domestic Rabbit, 
15 feet 2 inches ; in the Agouti, 17 feet 10 inches ; in the Porcu- 
pine, 25 feet. Rodents differ much in form and size, and their 
organs of locomotion are as variously constituted. They are 
adapted, according to the genus, either for running, jumping, 
climbing, flying, or swimming. Their toes are generally five in 
number, and touch the ground with the extremities only — a cir- 
cumstance which is favourable to agility. They are armed with 
sharp claws, enabling them to climb trees or to burrow in the 
earth. 
The greater number of Rodents have their bodies covered with 
fine, soft, and sometimes prettily- coloured hair, which man has 
turned to advantage. The small Grey Squirrel and the Chinchilla 
both furnish furs of value ; and the coats of the Beaver, the Hare, 
and the Rabbit, are used in several of our manufactures. 
The Rodents do not, like the other Orders of Mammals, admit 
of any great divisions, based on natural characteristics which 
are readily and clearly marked. When such have been adopted 
by naturalists, they have been founded on nothing but certain 
subtle features of organisation. We shall not, therefore, in this 
case, classify them in families ; but confine ourselves to describing 
the genera one after the other, grouping under a common head 
those which are connected together by certain actual affinities. 
The order of Rodents commences with a very numerous group, 
that of the Rat genus, which includes, besides the Rat proper, the 
Field Rats and Mice, the Ondatras, Musquash, or Musk Rats, the 
Hamster Rats, the Dormice, and the Jerboa Rats. All these 
animals have a kind of family likeness to one another, and differ 
but little in the eyes of the vulgar, who mix them all up under 
the same general denominations. These form the Mus species of 
the naturalists (from Mus, Mouse or Rat). 
Rats . — Rats proper are characterised by an oblong-shaped 
head, furnished with stiff feelers on each side of the Inuzzle ; by an 
elongated body terminated by a tail equal to it in length, and almost 
bare, scaly, cylindrical, and tapering down to the tip. They have 
but four toes on the fore feet, and the number of their teats varies 
from four to twelve. They are usually of a tawny or brown colour. 
