The ear is hidden by hair, and is small; so also is the eye, which is black. The nostrils open downwards, at the inferior border of a large cartilage. The mouth is small, and there are eight teeth on both sides in both jaws. They are simple molars, and are separate and cylindrical. The head is large behind, and the jaws come almost to a point, and the lower has a long ascending ramus. A great passage for the spinal cord, and the two processes on the frontal bone, add to the curious appearance of this “bumpy” skull. The pelvis is remarkable in its structure, and is open in front.
Some of these animals have the bands of the armour not attached, as has been mentioned, to the muscles of the back and to the head, but have them adherent to the skin of the back to the edge; and the sides and under part of the body are then covered with woolly hair. These are the largest animals of the two, and are found in Bolivia. The others are from Mendoza and Chili. These curious animals live, partly, mole-like lives.
From what may be gleaned by reading the previous pages about the Edentates, it will appear that the order is a very remarkable one, and that it is interesting on account of the different external appearance of the species, their diverse modes of life, and singularly restricted localities. Evidently, there has been much degeneration in some of the anatomical characters of many of the species, and especially in those whose foot bones and neck vertebræ have joined more or less. The singular resemblance which some species present, in various points of their anatomy, to the lower animals, is very interesting, as is also their wonderful relation, in points of structure, with a number of extinct Edentata, most of which were gigantic.
The Edentata, called also Bruta by Linnæus, form an order, the characters of which are, that there are teeth of one or two kinds all very similar, and often wanting. The incisors are not developed except in one group, and the rest have either molars which are separate, and numerous and simple, or there are none. The extremities are clawed, and the tongue is more or less elongated. The great groups of this order are the Tardigrada, or slow movers, which have a short face, long limbs, and small tail, and the body is covered with crisp hair; and the Effodientia, or diggers, which have long faces and worm-like tongues, with short limbs.
The Sloths form the only family of the Tardigrada, and the Effodientia are divided into the genera Manis, the scaly Ant-eaters; Dasypus, the Armadillos; Chlamydophorus, the Pichiciagos; Orycteropus, the Ant-Bears; and Myrmecophaga, the American Ant-eaters. The Sloths form three genera—Cholœpus, Bradypus, and Arctopithecus. Amongst the Ant-eaters, the genus Manis may stand alone. The genus Dasypus may be divided, for the sake of convenience, into the subdivisions Priodontes, Kabassous, Euphractes, Cachicames, and Tolypeutes. The other genera need no subdivision.
The fossil Edentata are mostly gigantic, and formerly lived in Europe and in the Americas. The European kinds would, were they now living, belong probably to the group of Pangolins, and they are placed in the extinct genera Pervatherium, Macrotherium, and Ancylotherium. In the Pliocene deposits of North America, there are large Edentates belonging to the genus Morotherium, and the previous Miocene deposits contain Moropus. The later, or Post-Pliocene strata of North and South America, contain species of Mylodon and Megalonyx, Megatherium, Scelidotherium, Cœlodon, and Sphenodon; they constitute a group of Terrestrial Sloths—the Gravigrada. In Cuba, the fossil huge Gravigrade Sloths are of the genera Megalocnus and Myomorphus. The Armadillo group are found fossil in South America, and the genera are Chlamydotherium, Euryodon, Heterodon, Pachytherium, and Schistopleuron. The modern genera are found with these, and the gigantic Armadillo-like animal, the Glyptodon, lived contemporaneously with the others, and possessed many strange peculiarities in its skeleton. The Ant-eaters are represented by a fossil form called Glossotherium. The oldest Edentates of the American Continent are found in North America, unless there is a Miocene group of them in South America, which is by no means an improbable supposition. The European Ant-eaters now found fossil lived in the Eocene, Miocene, and Pliocene ages.
With regard to the discovery of recent and closely-allied species of Manis, in South Africa and Hindostan, it may be said that they are relics of the old forms of the intermediate and now sunken land, between Eastern Africa and India, which existed before the last upheaval of the Himalayas. The evident structural affinity between the Effodient Edentata of South America and Africa, although the genera are different, adds to the interest of the corresponding, and in some instances greater, resemblance of many African and South American fresh-water fish and plants. The geologist looks back in the remote ages of the globe, when the great land surfaces and seas of the world were rather across the earth than in their present longitudinal position, in order to explain this remarkable similarity.
P. MARTIN DUNCAN.
