156 ZOOLOGICAL GARDENS. 
they were not yet fully developed, and he now admits 
that in the adult animal they are furnished with true 
roots, and are consequently incapable of receiving any 
addition to their growth when once completely formed. 
Their flattened crowns sufficiently indicate that the 
food which they are intended to masticate is entirely 
vegetable. 
In the regularity of their line of profile from the back 
of the head to the extremity of the nose, the lateral 
position of their diminutive eyes, the depth, obliquity, 
and obtuseness of their muzzle, the vertical fissure of 
their upper lip, the softness and closeness of their fur, 
and the greater length and muscularity of their poste- 
rior limbs, the Beavers may be regarded as almost 
typical of the Order to which they belong. They 
exhibit, however, in their external form several striking 
modifications peculiar to themselves. Of these the 
most remarkable consists in their tail, which differs in 
structure from that of every other quadruped. This 
organ, which is nearly half as long as the body, is 
broadly dilated, oval, flattened both above and below, 
covered at its thickened base alone with hair similar to 
that which invests the rest of the animal, but overlaid 
throughout the greater part of its extent with a peculiar 
incrustation which assumes the form of regular scales 
closely resembling those of fishes. The feet all termi- 
nate in five toes, those of the anterior extremities 
smaller and shorter than those of the posterior and 
divided almost to the base, while the latter are united 
to their very tips by the intervention of a strong dupli- 
cature of the skin, which allows of their separation to 
a considerable extent and forms a broad and palmated 
expansion, similar in form and serving for the same 
useful purpose with the webbed feet of the swimming 
birds. The nails are thick and strong; and that of the 
