The progress of dentition will at this period afford some farther data; towards the end of the _seventh_ month the middle INCISOR teeth of the inferior jaw perforate the texture of the gums; and soon afterwards the corresponding INCISORS of the upper maxilla make their appearance; then the lateral INCISORS of the inferior, and subsequently those of the superior jaw; about the _twelfth_ or _fourteenth_ month, sometimes sooner, the first of the MOLARES of the under, then the corresponding teeth of the upper jaw appear; the four CUSPIDATI are usually protruded through the gum the last; thus the CUSPIDATI and the second MOLARES will sometimes appear at the same time, and this is usually between the _twentieth_ and _twenty-fifth_ month; so that at, or soon after _two years_ of age, the twenty temporary or _milk_ teeth[269] are to be found in situ. It must however be remembered that the formation and appearance of the _milk_ teeth are subject to considerable variety, and there are some examples on record, though very uncommon, of children born with two Incisors in the upper maxilla, but such teeth have been found to be imperfect in their structure, and without fangs, and they have consequently soon been detached; in other cases, children, although enjoying perfect health, have not cut a single tooth until the end of their second year. Nor are the other signs to which we have alluded, as affording indications of the age, to be considered as immutable; the infant may have been more or less retarded, or accelerated in its march of developement by its state of health and vigour, and it deserves remark, that scrophulous and _rickety_ children very commonly present an aspect of intellectual precocity, by no means commensurate with their age; and hence the popular notion has arisen, that very intelligent children rarely continue to live. The fact of this premature expansion of the mind is too apparent to be doubted; but philosophers have endeavoured to explain it upon very different principles; the physiologist has sought the cause from some peculiarity in the organization of the body, while the moralist has attempted to account for it by supposing that in consequence of the inability of these subjects to partake of the sports and exercises suitable to their years, they necessarily enjoy more of the instructive society of their parents and preceptors.