I am just recovering from an attack of illness, or I would certainly have sooner acknowledged your kind attention in sending me six copies of your report on my Collection from Sacrificios, for which I beg to return you my best thanks.

Your observations on the whole coincide with my own preconceived opinions, with the exception of what I consider one of its most important points; I allude to the antiquity of the collection, which you consider to have been the work of the Aztecks, or comparatively modern Mexicans, of the period of the Conquest by Cortez. You will I hope excuse me if I differ from you in this respect, and that you will permit me to make the following observations thereon. I premise by stating, that by far the greater portion, and indeed the best of the specimens, were found at a depth of from ten to fourteen feet in rich dark soil; my objections, therefore, to your view of the case is principally founded on the geology of the island of Sacrificios.