Our knowledge of the limits of animal life have been notably extended during the year which has just departed. Air, blown upon an adhesive surface by the aeroscope on the summit of Etna, twelve thousand feet above the sea level, has been found to contain large quantities of Diatomaceæ; and thus the presence of a zone of life has been discovered to us, soaring not only above the limits hitherto fixed, but above the range of physical phenomena in the mountain itself.

And now the ocean-depths have given up a secret as marvellous. We are taught that at a depth below the surface nearly as great as the height of the infusorial zone above it, animals as high in the scale of being as starfishes are enjoying life. The one discovery is a fitting pendant to the other, and yet, how great is their difference! In the one case the extreme ratification of the atmosphere seemed to our notions to render life impossible; in the other, the enormous pressure of the opposite element, which in the homes of these starfishes must amount to at least a ton and a-half on the square inch, is so greatly at variance with our belief, that we are confounded at the very outset of the inquiry. The capability in an animal so well accustomed to air as the starfish—whose ordinary domain is the seabeach—to exist without it, and its inherent power of withstanding a pressure that would upon the surface grind a rock to powder, are studies replete with instruction and value—studies which can be turned to a good geologieal account, and made to bear reference to a past fauna as well as to a living one.