One who knows anything about the structure of animals' bodies need not be told that the jerboa is a rodent. One glance at the peculiar shape of his head would assure him of that. The form of the rest of its body, especially its long hind and short fore legs, give unmistakable proof that it is related to the jumping rodents; it belongs, in a wide sense, to the family of the jumping mouse, the scientific name (Dipodidea, two-footed) of which is very significant, as the very short fore legs are usually carried close under the chin and are scarcely noticeable when the animal is in its normal position, and are of little use when it moves about. The hind legs are very strong, and when going at full speed the jerboa takes jumps that measure from eight to ten yards, according to the unanimous testimony of various witnesses. The jumping mouse of North America, which is somewhat larger than an ordinary mouse, is, according to Brehm, also as swift as an arrow or a low-flying bird. This exceptional velocity is not all that reminds us of a bird, for there is also a strong resemblance in the formation of certain parts of the bodies of the two creatures; but, after consideration, this should not seem strange, because in animal organisms similar means are employed to accomplish similar ends. It is only natural that there should be peculiarities in the construction of the limbs and skulls of the Dipodidea with their bird-like movements and bird-like sharp-sightedness, that are usually found only among birds. The consistency between the construction of their bodies and their mode of life is a beautiful example of fitness; only by extraordinary quickness of movement and sagacity could the little defenseless plant-eaters maintain the struggle for existence in the barren steppes and deserts. The formation of the bodies of the different members of the family varies according to their needs. The jerboa is the largest member of the family. Very little is known of his life when free; it being known only that the jerboas are widely spread over the whole of southern Africa, and are nocturnal burrowers of the steppes. During the rainy season they remain in a sort of winter sleep.--_Dr. L. Heck, in the Illustrirte Zeitung_. * * * * * NEW OBSERVATIONS ON THE LANGUAGE OF ANIMALS. By M. DE LACAZE DUTHIERS, of the Institute of France.