The neck of the figure is stretched out and slightly curved, and its mouth is opened wide, as if in the act of swallowing or ejecting an oval figure, which rests partly between the distended jaws. This oval is formed by an embankment 4 feet high, and is perfectly regular in outline, its transverse and conjugate diameters being 103 and 39 feet respectively. The combined figure has been regarded by some as a representation of the oriental cosmological idea of the serpent and the egg. With the remains of the dead in the sepulchral mounds, as also within those which are believed to have been connected with the religion of their builders, many relics of art have been discovered, displaying greater skill than was known to exist among the tribes found in occupation of the country at the time of the discovery. Elaborate carvings in stone, pottery often of elegant design, articles of use and ornament in metal, silver, and native copper from Lake Superior, mica from the Alle-ghanies, shells from the gulf of Mexico, and obsidian, probably also porphyry, from Mexico, are found side by side in the same mound. Articles of comparatively recent date, some of them of undoubted European origin, have also been found among the later and secondary deposits in the mounds.

Forged inscriptions, stones bearing mysterious characters, "Erse, ancient Greek, Phoenician, Celtiberic, and Runic," as evidences of every possible and impossible theory of American origin, have each found people credulous enough to accept and defend their authenticity, even after the authors of the various impostures have abandoned them to their fate. The facts connected with the monuments of the Mississippi valley " indicate that the ancient population was numerous and widely spread, as shown from the number and magnitude of their works, and the extensive range of their occurrence; that it was essentially homogeneous in customs, habits, religion, and government, as appears from the great uniformity which the works display, not only in respect to position and form, but in all minor particulars; and that the features common to all the remains identify them as appertaining to a single grand system, owing its origin to a family of men moving in the same general direction, acting under common impulses, and influenced by similar causes." What-ever differences the monuments display are such as might result from the progressive efforts of a people in a state of development, or from the weaker efforts of colonies, or what might be called provincial communities.

It is impossible that a population for whose protection such extensive military works were necessary, and which was able to defend them, should not have been eminently agricultural; and such monuments as the mounds at Grave Creek and Cahokia indicate not only a dense agricultural population, but a state of society essentially different from that of the existing race of Indians north of the tropic. There is not, and there was not at the period of the discovery, a single tribe of Indians, north of the semi-civilized nations of Mexico and Central America, which had the means of subsistence to enable them to supply for such purposes the unproductive labor necessary for the work; nor were they in such a social state as to compel the labor of the people to be thus applied. As regards the an- tiquity of these monuments, apart from such facts as a total absence of any reasonable tra- ditions as to their origin among the Indians themselves, and the existence of the largest and most ancient forest trees on the embankments and in the ditches of the various works, there are other facts which enable us to arrive at approximate conclusions upon this point.

None of these works occur on the lowest formed of the river terraces which mark the subsidence of the western streams; and as there is no good reason why their builders should have avoided erecting them on that terrace, while they raised them promiscuously upon all the others, it seems to follow that this terrace has been formed since these works were erected; a conclusion supported by the important fact that some of them have been in part destroyed by streams which have since receded for half a mile and upward, and which under no present possible rise, from rains or other natural cause, could reach the works again. Upon these premises, the time since the streams have flowed in their present courses may be divided into four periods, corresponding to the four terraces which mark the eras of their subsidence, of which period the last and longest (since the excavating power of the streams diminishes as the square of their depth increases) has elapsed since the race of the mounds flourished. An-other fact bearing upon the question of the age of these works is the extremely decayed condition of the human remains found in the mounds.

Considering that the earth around the skeletons is for the most part wonderfully compact and dry, and that the conditions for their preservation are exceedingly favorable, while they are in fact in the last stage of de-composition, we may form some approximate estimate of their remote antiquity. In the barrows of the ancient Britons, in a moist climate and under unfavorable conditions as regards preservation, entire and well preserved skeletons are often found possessing an undoubted antiquity of at least 1,800 years. From these and other facts and circumstances equally conclusive, we may deduce an age for most of the monuments of the Mississippi val- ley of not less than 2,000 years. By whom built, and whether their authors migrated to remote lands under the combined attractions of a more fertile soil and more genial climate, or whether they disappeared beneath the victorious arms of an alien race, or were swept out of existence by some direful epidemic or universal famine, are questions probably beyond the pow- er of human investigations to answer. - The principal remains of antiquity in Mexico are the ruins of temples and of structures dedicated to defensive purposes.