fish is the lowest form of the vertebrate type of animals, and the scale upwards to man is marked by the differentiation of limbs. They are undeveloped in the fish, and they rise, through innumerable steps, to perfection in the human species. Comparing the solar with the vertebrate system, the moon, with its naked ball, may represent the undeveloped form of the fish, and Saturn the highest form of vertebrate animals. When we speak of the typical perfection of a planet, we do not at all refer to its adaptation to life. We mean merely the degree in which the distinguishing characteristics of a general style are exhibited. The grand characteristic is the concentricity of structure, which we before traced in the sun. In the sun, we have seen that there are successive envelopes or shells around the core. Three of these were recognised before the last total eclipse, and the phenomena of the eclipse have clearly established, what was before surmised, another envelope of rose-coloured matter; and, extending beyond this stratum, there is the corona, which is, most probably, the atmosphere in which all the others are suspended, like strata of clouds at different heights of our atmosphere. If we accept the hypothesis of the Astronomer-Royal, that the corona is due to our atmosphere reaching nearly to the moon, we shall be forced to admit that this atmosphere exists as a zone or ring encircling the earth. It cannot be the ordinary atmosphere of the earth. Well-known dynamical conditions forbid this supposition. We must suppose
