Mastodon (Gr.Mastodon 110094 , nipple, andMastodon 110095 tooth), an extinct proboscidian mammal, coming near the elephant, found either in the tertiary or more recent deposits in all quarters of the globe except Africa. This animal has the vaulted and cellular skull of the elephant, with large tusks in the upper jaw, and heavy form; from the characters of the nasal bones and the shortness of the head and neck, it has been concluded that it had a trunk; the crowns of the molars are divided by transverse rows of mannuillary conical prominences, whence the name; besides the upper incisors or tusks, the cheek teeth are (6/6)-(6/6), succeeding each other from behind forward, as in the elephant, only two or three being in use at a time; during youth there were two short and straight tusks at the end of the lower jaw in the males, which were retained sometimes to adult life. The best known species is the North American mastodon (M. gigantcus, Cuv., or M. Ohioticus of Falconer); this has been fully described in a superb work by Dr. John C. Warren, assisted by Dr. J. F. W. Lane (" The Mastodon Gigan-teus of North America," 2d ed., 4to, Boston, 1855), to which the reader is referred for the fullest details and abundant illustrations of most of the species.

A few remains of the mastodon had been discovered in North America as early as 1705, but not until 1801 was anything like a complete skeleton obtained, when a tolerably complete one was procured from the morasses of Orange co., N. Y.; this was carried to London in 1802, but was soon returned to this country, where it occupied a prominent place in Peale's museum at Philadelphia until 1849 or 1850, when it suddenly disappeared; it was imperfect, wanting a considerable part of the head, some vertebrae, ribs, and bones of the limbs; it was believed by Dr. Warren to have fallen into the possession of Prof. Kaup of Darmstadt, Germany. Another skeleton, less perfect than the last, obtained at about the same time, was exhibited in Baltimore for years, and in a dismounted state came into the possession of Dr. Warren of Boston in 1848, where it still remains. About 1840 Mr. Koch procured a rich collection of mastodon bones from the banks of the Missouri, and put together a nondescript animal, the so-called Missourium, which drew crowds of visitors in New York and London, until from the mass of bones of several individuals a tolerably complete skeleton was made up by Prof. Owen, which is now in the British museum.

The skeleton now at Cambridge, Mass., was discovered in Warren co., N. J., in 1844; with this young female were found four very perfect heads, a number of fine teeth, and several bones. The finest skeleton of this species is the one described by Dr. Warren in the work above mentioned; it was discovered at Newburgh, N. Y., in 1845, in a swamp usually covered with water, but left dry daring that summer; it is now in Boston. Specimens have been found in New York, New Jersey, Indiana, Kentucky, Alabama, Missouri, Kansas,' Texas, and other states, and as far as hit. 65 N. - Taking Dr. Warren's specimen as the type of this species, the cranium is flatter than 'in the elephant, narrow between the temporal fossa, the face becoming twice as wide be-low the nasal opening; the length of the superior surface, from the vertex to the edge of the pre-. maxillary bones, is 48 in., and the width between the superior orbitar processes 28 in.; the posterior or occipital surface is nearly vertical, roughened for muscular attachments; the temporal fossae are of great size, indicating the power of the muscles which filled them; the zygomatic processes thick and strong; lower jaw V-shaped, the anterior pointed extremity having on the internal surface a long wide groove for the tongue.

The cervical vertebra have short spinous processes, except the last, which is 6 1/2 in. long; the dorsals are 20, and. with the 3 lumbar, form a considerable arch, the first 7 having very long spinous processes (that of the 3d, the longest, being 23 1/2 in.), and thence gradually diminishing to the last, which is only 4 in.; the transverse processes are also very thick in the first seven; the first lumbar measures across the transverse processes 17 in., of which the body is only 5 in.; the sacrum consists of five bones, and is 20 in. long on the lower surface; caudals probably about 22, very strong at the commencement of the tail, which reached to the knees. The pelvis is very strong and massive, 6 ft. 2 in. wide across the anterior superior spinous processes; thorax rounded, its anterior opening 2 ft. from above downward and 1 ft. transversely; sternum keeled below, with a stout pointed protuberance in front. The ribs are 20, 13 true and 7 false, the first nearly vertical and resembling a clavicle, and 28 in. long; from this the ribs increase to the ninth, which is 54f in., and thence decrease to the last, which is 21 in.; the fifth, flat anteriorly, is 4 in. wide; after the seventh they become rounded; they are not unfrequcntly found united, as after fracture.

The scapula is more nearly equilateral and in this respect more human than in the elephant, and like some of the other bones might in rude ages be easily mistaken for the remains of giant men; its spine is nearly vertical, bifurcating below, the infra-spinons fossa more than three times as ample as the supraspinous, the former having generally a depris-sion near the spine; the glenoid cavity is 11 by 5 in. The massive humerus is 39 in. long, and the same in its greatest circumference, with a remarkable projection extending two thirds down the limb for the deltoid muscle; the circumference of the elbow joint is 44 in.; radius 29 in. long and 6 1/2 in. wide below; the ulna much the stoutest, and 34 in. long. The fore foot measures nearly 2 ft, across; the wrist has eight bones, in two rows of four each; metacarpals rive, the first or thumb the smallest (4- in. long), the second and fourth 5 in., the third (the largest) 6 1/2, and the fifth about 4 1/2; phalanges in thumb two, and in the others "three each, supposing an ungual phalanx to be present in all, though wanting in the skeleton.

The thigh bone is massive and about as long as the humerus, 17 in. in circumference at the middle and 30 at the lower portion; the knee pan nearly globular; tibia human-like, 28 in. long, 30 in. in circumference above and 13 1/2 in the middle; fibula 26 in., ascending less high than the tibia, but descending lower to form the external malleolus: feet more depressed, and the toes more radiating, otherwise much as in the elephant. This skeleton is 11 ft. high, 17 ft. from end of face to beginning of tail, the latter being 6 2/3 ft.; circumference around ribs 16 ft. 5 in.; tusks about 11 ft,, of which 8 2/3 project beyond the sockets. The teeth consist chiefly of dentine invested by enamel, though a layer of cement, thinner than in the elephant, invests the fangs and is spread over the crown. The whole number of teeth is 24, of which rarely more than 8 were in use at one time; they are developed from behind forward in order to relieve the jaws from the excessive weight of the whole at one time; the outer edge of the upper teeth projects beyond that of the lower. Two on each side in each jaw are developed soon after birth, and are shed early.

In the lower jaw, the first is small, 1 1/4 in. by 7/8, and 7/8 in. high, with two transverse bifid ridges slightly notched, and two projecting much curved fangs; the second, immediately behind it, has the same characters, but is larger, 1 3/4 by 1 1/4 in., and 1 1/8 in. high, with a prominent heel; the third is three-ridged and six-pointed, 3 by 2 in., and 1 1/2 high; the fourth is 3 1/4 by 2 1/2, and 1 5/8in. high, with the inner mastoid eminence notched; the fifth is 4 1/2 by 3 in., with the inner points notched; the sixth is four-ridged, with complex heel and deeper cleft furrows, 8 by 3 in., and 6 1/2 high; the last sometimes has five ridges. The first and second of the upper jaw resemble those of the lower; the third is three-ridged, 2 1/2 by 2 in.; the fourth is three-ridged, 3 by 2 1/2 in. (and sometimes much wider), with the eminences notched; the fifth is also three-ridged, 4 by 3 in., each with two eminences; the sixth is four-ridged, with a small heel, the points sometimes bifurcated, and the furrows deep, 6 1/4 by 3 in., sometimes larger, even to 9 1/2 by 5 1/2, and with five ridges. There is no evidence of an additional premolar under the second lower milk tooth, though there may be such in the upper jaw, as in other species of mastodon, and in the tapir.

At an advanced age the sixth tooth remains alone on each side above and below; in a case mentioned by Dr. Warren there was a seventh or supernumerary tooth on one side of the lower jaw, 7 in. long and 7 1/2 high. Besides the upper tusks, there are in the mastodon, though not in the elephant, inferior mandibular tusks. The food of the mastodon was entirely vegetable, as is proved by the remains of the twigs of coniferous trees, leaves, and other vegetable matter found between the ribs; and the animal doubtless resorted to marshy and boggy places, like other proboscidians, in search of succulent plants, where it was often mired in the very places whence its remains have been extracted during the 19th century. Around the Shawan-gunk skeleton were found tufts of dun-brown hair varying in length from 2 to 7 in.; so that the mastodon, like the Siberian mammoth, may have been clothed to withstand a climate considerably colder than that in which modern elephants live. The bones of M. gignnteus have not been generally found in a mineralized state; in Dr. Warren's specimen they are light-colored, of less specific gravity than recent bones, and retain from 27 to 30 per cent, of animal matter (bone cartilage); both bones and teeth, however, have been found silicified, and they are generally impregnated with iron, which it is well known has a great preserving power. - The geological position of the remains of this species has long been and still is a subject of dispute among geologists; in a few instances they are said to have been found below' the drift, in the pliocene, and even in the miocene; but they have generally been obtained from the post-pliocene or alluvial formations at a depth of from 5 to 10 ft., in lacustrine deposits, bogs, and beds of infusorial earth; Pomel and others consider them diluvial; the bones of this mastodon and of the fossil elephant have been found in company in Ohio, South Carolina, Texas, the pliocene of Nebraska, and various other parts of North America. Some have thought that the mastodons became extinct since the advent of man upon the earth, like the dinornis and the dodo; according to Lyell, the period of their destruction, though geologically modern, must have been many thousand years ago.

The same causes probably acted in their extinction as in the case of the fossil elephant, perhaps partly climatic changes, but more probably some great convulsion on the surface of the globe at an epoch anterior to man. - About 30 species of mastodon have been described, for details on which see the work of Dr. Warren and those referred to by him. In South America lived the M. Humboldtii (De Blainv.), belonging to the narrow-toothed group, of which the European M. anguxtidens is the type; this is characterized by the shorter rostrated extremity of the lower jaw, the apparent absence of lower tusks, and folds of enamel more complicated than in the teeth of 31. giganteus. 31. Andium (Cuv.), a smaller species, considered by D'Or-bigny the same as the last, had the same undulating folds of enamel, but a more elongated symphysis. The distinction between the 31. longirostris (Kaup) and the 31. angustidens (Cuv.) of Europe is not well made out, and authors differ exceedingly as to the limits of these species.

The division of Pom el seems as probable as any; he describes as M. longirostris (or Ariernensis, Cr. and Job.) those having a lengthened lower jaw, four ridges in the third, fourth, and fifth teeth, five and sometimes six in the ultimate molar, tusks in the lower jaw, and a vertical upper premolar; the 31. angustidens he limits to the Italian species, with the same narrow teeth and four ridges in the three penultimate molars, with no beak to the lower jaw as in 31. longirostris, or short truncated gutter as in M. giganteus, but with a long horizontal semi-canal slightly inclined downward. The bones, according to De Blainville, resemble more those of the Asiatic elephant than the American mastodon. Dr. Falconer, on the contrary, considers the M. angustidens and longirostris as perfectly distinct, and the former as more nearly related by a three-ridged penultimate molar to the M. giganteus than to the M. longirostris, placing the first two in the section trilophodon (with three ridges), and the last with the Asiatic species in the section tetralophodon (with four ridges to the third, fourth, and fifth molars). The famous Dusino mastodon (M. Turinensis), discovered near Turin in 1840 in a fluvio-lacustrine deposit, -described by Prof. Sismonda, whose description is partially reproduced with a figure in Dr. Warren's work, belonged to the 31. angustidens; in the same deposit were found remains of elephants and other large pachyderms.

Pomel's other species, less clearly made out, are M. Cuvieri, with a prolonged lower jaw and the three penultimate molars with three ridges; M. tapiroides, with tuber-culated teeth, forming a connecting link with those of the dinotherium (both of the last are found in central and southern France, the M. longirostris having been found in central Germany, at Eppelsheim); and the M. Buffonis, with short thick teeth, to which he refers the Siberian specimens. The age of the European mastodons was earlier than that of the American, their remains having been found as low as the miocene, and probably long anterior to the elephant, which was a contemporary of the American mastodon; according to Pome M. angustidens is found with 31. Bufonis in pliocene, and M. Cutieri and tapiroides in miocene lacustrine deposits; but at Turin bones of the elephant, rhinoceros, hippopotamus, and tapir were found with the Dusino specimen, so that the fossil elephant of the old world would seem to have been anterior to that of the new.

Pictet describes also M. brevirostru (Gervais), from the pliocene of the south of France, with the lower jaw short as in elephants, the lower tusks not at all or slightly developed, and the molars as in M. longirostris, with secondary tubercles between the ridges; he mention's other species as found in the pliocene of Puy and Auvergne. Two species found in Asia may be mentioned here in conclusion - the M. Sivalensis (Falc. and Cautl.), from the Sivalik hills, and the M. latidens (Clift), from the banks of the Irrawaddy; in the former the teeth are very large, the ultimate molars being from 8 to 9 1/2 by 3 to 3 1/2 in., with six ridges in the upper jaw, rounded mammillae, and rather narrow form; in the latter the form is broader, and the teeth sometimes with as many as ten ridges, and seemingly one of the links connecting mastodon with elephant; these belong to the section tetralophodon. The specific name of tetracaulodon given by Dr. Godman to some mastodon specimens, from their having two tusks in the lower jaw, is now generally admitted to be ill-founded; lower tusks are found in young males of many species, and sometimes one or both in the adult male, their presence being probahly a sexual and not a specific character.

Dr. Leidy and others have indicated several species of mastodon in Kansas and Nebraska, and other newly explored regions of North America; these are described in the " Proceedings " of the Philadelphia academy of natural sciences. Several specimens have been found near Cohoes and Ithaca, N. Y., and recent explorations have indicated their presence in ail the middle, northern, and western states. - According to Owen, the mastodons were elephants with molars less complex in structure and adapted for coarser vegetable food, ranging in time from the miocene to the upper pliocene, and in space throughout the tropical and temperate latitudes. The transition from the mastodon to the elephant type of dentition is very gradual.

Mastodon giganteus.

Mastodon giganteus.

Skeleton of Mastodon.

Skeleton of Mastodon.

Tooth of Mastodon.

Tooth of Mastodon.