It was early observed that if the dark regions really are seas, the proportion of water to land upon Mars is much smaller than upon the earth.
For two especial reasons Mars has generally been regarded as an older or more advanced planet than the earth.

The first reason is that, accepting Laplace's theory of the origin of the planetary system from a series of rings left off at the periphery of the contracting solar nebula, Mars must have come into existence earlier than the earth, because, being more distant from the center of the system, the ring from which it was formed would have been separated sooner than the terrestrial ring.

The second reason is that Mars being smaller and less massive than the earth has run through its developments a cooling globe more rapidly.

The bearing of these things upon the problems of life on Mars will be considered hereafter.
And now, once more, Schiaparelli appears as the discoverer of surprising facts about one of the most interesting worlds of the solar system.
During the exceptionally favorable opposition of Mars in 1877, when an American astronomer, Asaph Hall, discovered the planet's two minute satellites, and again during the opposition of 1879, the Italian observer caught sight of an astonishing network of narrow dark lines intersecting the so-called continental regions of the planet and crossing one another in every direction.

Schiaparelli did not see the little moons that Hall discovered, and Hall did not perceive the enigmatical lines that Schiaparelli detected.