Indeed, it is both diverting and instructive to observe how Nature permits, and even seems to abound in, curious coincidences and striking resemblances between things of entirely diverse character. The dried polyp, called “encrinoid echinoderm,” bears a wonderful likeness to one species of Indian corn. (See the plate at p. 137 of Mr. Rymer Jones’s beautiful work on “The Animal Kingdom.”) And the other day, when I was enjoying a leisure hour in the British Museum, I suddenly remarked that the “carapace” (back-shell) of the splendid fossil specimen of the “Holoptychius nobilissimus” in one of the cases might serve for a sketch of the back of a _capercailzie_, where the grey and purple feathers overlap one another. Yet here is no _real_ connection whatever. Only Dame Nature had gone to play. _Secondly._ The preservation of these “polyp” forms, in the manner in which they _have_ been preserved, seems to me to be due to a feature or circumstance which is strictly animal and not vegetable. I refer to the fact of the creature, while it was alive, _inhabiting a house_, a house built by himself, or emanating from his own substance. For, just as we could know but little of the existence or habits of “shell-fish,” were it not for their _shells_, so I think we may assume that the _choanite_ must, when alive, have dwelt in a tough, horny “coperculum,” answering to the shape of his body and the number of his “polyps” (if he was a _compound_ creature), because otherwise he would have been like a jelly-fish or naked slug, and his “polypary” could not have been preserved in a stony fossil. Of course, whatever was merely flesh, or adipose matter, has long since perished; but the _house_ or shell in which it whilome dwelt remains. Thus, the “echinus” built himself a _dome_, such a residence as a _hedgehog_ would require to live comfortably in, and through the various orifices of which his spines could be protruded at pleasure. The “ammonite,” being shaped like a _snake_, preferred living in a shell of that form, where the creature when coiled up was safe. The “alcyonite” had a more exquisite taste in house-building, answering, we may be sure, to the complex and beautiful structure with which the great Creator had endowed him. His home was a palace, containing long galleries and secret doors and wheel-windows; and here some of the delicate tubes are fringed at their extremities like the petals of a flower. The antiquity of these formations may be very great, we can scarcely tell how far removed from our own era. For, while the zoophyte itself is of a perishable nature, we are acquainted with no substance more durable (if we except the gems) than that calcareous matter of which these tubes and plates were formed, when once it has been subjected to processes of infiltration by crystallizing mineral and metallic oxides.