ORDER VII.—_Cheiroptera_[23] (wing handed). Bats are not generally favorites, and are by many regarded with aversion. Their strange and rather uncomely forms are seen on wing only in the dim twilight, as they spend the day mostly in deserted buildings and gloomy caverns. In eastern countries, where such receptacles of the dead are common, bats are often found in sepulchers or catacombs, and are regarded as fit dwellers with desolation and death. There are many species, with enough variety in their appearance; and the study of their natural history softens prejudice and reveals much of interest in their structure and habits. ORDER VIII.—_Rodentia_[24] (gnawing animals). Animals of this order have two large, chisel-like incisors in each jaw, and, separated from them by a wide space, are the molar teeth. The incisors never cease growing from the roots, but are constantly worn away by nibbling. The lower jaw moves backward and forward. This order includes more than half of the known mammals, and its representatives range from the equator to the poles. Hares, Mice, Rats, Squirrels, and Beavers are among those best known. ORDER IX.—_Ungulata_[25] (hoofed animals). An order of mammals most valuable to man. They are grouped in two divisions, according to the number of toes. The uneven-toed ungulates include the Elephant, Rhinoceros and Horse. The elephant is marked by the prolongation of the nose and upper lip into a trunk or proboscis, which is said to contain over 40,000 muscles. It has no canine teeth, and incisors only in the lower jaw. Elephants are found in Asia and Africa. There are two extinct species, the mastodon and mammoth. The rhinoceros is a native of Africa and India. It is an immense animal, covered by a hairless skin, which lies in folds on the body. The nose bears one or two horns, which grow sometimes three feet in length. The horse includes animals having one toe upon each foot, upon which they walk. The family includes the Ass, Zebra and Quagga. The even-toed ungulates include all the _Ruminates_, or cud chewing animals, with the Swine and Hippopotamus. The ruminants are remarkable for their peculiar method of digesting their food. They possess a very peculiar stomach, of four compartments. The food, mixed with saliva, is swallowed and passes into a paunch where it is mingled with water, and then forced into what is called the honey-comb stomach, a sack in which the food is formed into cuds, and by a muscular arrangement is forced back into the mouth to be masticated a second time before passing directly into the third stomach or manyplies, where it is strained, and then driven into the true stomach to be acted upon by the gastric juice and assimilated.