These crania possess an unusual interest, inasmuch as, with two exceptions, they present the horizontally elongated form, in every degree from its incipient stage to its perfect development. By what contrivance has the rounded head of the Indian been moulded into this fantastic shape? I have elsewhere[17-+] offered some explanations of this subject; but the present series of skulls throws yet more light on it, and enables me to indicate the precise manner in which this singular object has been attained. It is evident that the forehead was pressed downwards and backwards by two compresses, (probably a folded cloth,) one on each side of the frontal suture, which was left free; a fact that explains the cause of the ridge, which, in every instance, replaces that suture by extending from the root of the nose to the coronal suture. To keep these compresses in place, a bandage was carried over them from the base of the occiput obliquely forwards; and then, in order to confine the lateral portions of the skull, the same bandage was continued by another turn over the top of the head, immediately behind the coronal suture, and probably with an intervening compress; and the bandaging was repeated over these parts until they were immovably confined in the desired position. Every one who is acquainted with the pliable condition of the cranial bones at birth, will readily conceive how effectually this apparatus would mould the head in the elongated or cylindrical form; for, while it prevents the forehead from rising, and the sides of the head from expanding, it allows the occipital region an entire freedom of growth; and thus without sensibly diminishing the volume of the brain, merely forces it into a new though unnatural direction, while it preserves, at the same time, a remarkable symmetry of the whole structure. The following outline of one of these skulls, will further illustrate my meaning; merely premising that the course of the bandages is in every instance distinctly marked by a corresponding cavity of the bony structure, excepting on the forehead, where the action of a firm compress has left a plane surface. [Illustration] This conformation, as we have already observed, was prevalent among the old Aymara tribes which inhabited the shores and islands of the Lake of Titicaca, and whose civilization seems evidently to antedate that of the Inca Peruvians. I was in fact at one time led to consider this form of head as peculiar to, and characteristic of, the former people; but Mr. Foster's extensive observations conclusively prove that it was as common among some tribes of the sea coast, as among those of the mountainous region of Bolivia; that it belonged to no particular nation or tribe; and that it was, in every instance, the result of mechanical compression.