Can the fishes of the Old Red be considered the embryos of those of later epochs? Of course they are the first types of the vertebrate series, including the most ancient of the Silurian system; but they each constitute an independent fauna, as numerous in the places where these earlier fishes are found, as the present fishes in any area of similar extent on our sea-shore to-day. I now know one hundred and four species of fossil fish from the Old Red, belonging to forty-four genera, comprised under seven families, between several of which there is but little analogy as to organization. It is therefore impossible to look upon them as coming from one primitive stock. The primitive diversity of these types is quite as remarkable as that of those belonging to later epochs. It is nevertheless true that, regarded as part of the general plan of creation, this fauna presents itself as an inferior type of the vertebrate series, connecting itself directly in the creative thought with the realization of later forms, the last of which (and this seems to me to have been the general end of creation) was to place man at the head of organized beings as the key-stone and term of the whole series, the final point in the premeditated intention of the primitive plan which has been carried out progressively in the course of time. I would even say that I believe the creation of man has closed creation on this earth, and I draw this conclusion from the fact that the human genus is the first cosmopolite type in Nature. One may even affirm that man is clearly announced in the phases of organic development of the animal kingdom as the final term of this series. Lastly: Is there any reason to believe that the Ichthyosaurians are descendants of the Sauroid fishes which preceded the appearance of these reptiles? Not the least. I should consider any naturalist who would seriously present the question in this light as incapable of discussing it or judging it. He would place himself outside of the facts and would reason from a basis of his own creating. . . In the "Revue Suisse" of April, 1845, there is a notice of the course of lectures to which reference is made in the above letter.