( Originally Published 1936 )
THE order Rodentia includes a great number of animals? many of which have much external resemblance to the Insectivora, but which may always be distinguished from them by the two incisors in each jaw, above and below, the upper pair being very strong, curved and rootless. Behind these is sometimes present a small additional pair. The canine teeth are always, and the premolars some-times, absent, but there are generally the three molar teeth on each side, above and below. In any case, the incisors are widely separated from the other teeth, furnished with a cutting edge, and as they are continually worn down by use, grow throughout life. If one of the opposing teeth is lost by any accident, the other, not being worn down as it should be, continues to grow until it may finally cause the death of the animal.
All the Rodents are mainly vegetable feeders, though some are practically omnivorous, and many are highly destructive to crops and stores. Some species are valued for their furs, and others form important articles of diet. Indeed, animals of this order are used by man as food in many parts of the world, hares, rabbits, and squirrels being commonly eaten by Europeans and Americans, rats and mice by the Chinese and sometimes by the Egyptians, and other rodents by various other peoples.
FAMILY SCIURIDAE (SQUIRRELS)
This is a very large family, comprising many different species, most of which are tree-living; some have their limbs connected by membranes which may be expanded to enable them to take flying leaps through the air; and some are ground-living animals. They feed on birds, young shoots, nuts, acorns, and so on, using their fore-feet much like hands, to hold food to the mouth, and they are common in many parts of the world.
Flying Squirrel (Sciuropterus volans)
The Flying Squirrels are at once distinguished by the large expansion of skin, or membrane, connecting the fore and hind legs, by the aid of which they are sustained in the air and enabled to take enormous flying leaps from tree to tree. The colour of the species figured varies from lighter or darker grey or brown to reddish. They measure about eighteen inches in length, including the tail. See Plate 15, Fig. 69. It is a night animal, exclusively tree-living, and is common in Oriental countries.
The beautiful little Flying Squirrel of America (Sciuropterus volucella) is about twelve inches in length, including the tail, is covered with extremely fine, soft fur, and has enormously large dark and expressive eyes. These little creatures are often kept as pets, but they are active only at night, sleeping during the day rolled up in a ball. They have no power of true flight, as might be supposed from the name, but simply plunge headlong from a height, at the same time spreading out their legs and distending the membrane, forming an aeroplane, which serves to hold them up as they come diagonally to the ground. The membrane, however, does not enable the animal to rise from the ground, and is only useful in descent, or in short leaps.
Squirrel (Sciurus vulgaris)
This pretty little animal is found throughout the greater part of Europe and Northern and Central Asia. The typical European form is russet-red above and white below, but in Asia the red colour is more often replaced by grey, sometimes shading almost into black. The ears are erect and tufted, the tail is very bushy, and always carried erect when the animal is running on the ground, but when leaping it is ex-tended behind and serves at once as a rudder and as a parachute. See Plate is, Fig. 68. The Squirrel does not hibernate, but lays up stores of provisions in hiding-places on which it can subsist during the winter. Besides the vegetable substances on which it feeds, it will also plunder birds' nests of eggs and fledglings.
Several species of Squirrel are found in America, among the more common of which are the Red Squirrel (Sciurus Hudsonius), the Grey Squirrel (Sciurus Carolinensis), and a large form known in the South-ern States as the Fox Squirrel (Sciurus Cinereus). The first of these is a small animal, about the size of the European species, but without the tufts of hair on the ears that distinguish that genus. It is very pugnacious and is said to be able to drive away the larger and more powerful Grey Squirrel from any region that it wishes to occupy. As usual with all animals, black forms are found that were formerly regarded as separate species, but are now known to be only varieties. The Grey Squirrel is now common in many of the Eastern States, but is more a Middle-Western form. It is one of the largest of the family, in winter is thickly clothed with silvery-grey hair, has a large and bushy tail, and in habits is similar to the other species mentioned. See Plate 15, Fig. 67.
A very beautiful little animal common to our Eastern States, and that may often be seen running along stone walls in the country is the Chipmunk (Tamias striatus), one of the ground squirrels. Unlike the tree-squirrels, members of this genus are provided with cheek pouches, in which they hold their food. The colouration of this lovely little creature is very striking, the back being a bright red, interspersed with lengthwise lines of deep brown and one or two streaks of white. See Plate 15, Fig. 71. It is very shy, and although living close to human habitations, is seldom seen in captivity.