Marvels of the Universe 847 
have been fitted for rapid movement ; and in this case the tail-flap also served as a propeller. One 
of the chief points of interest in Pterygotus, which was six feet in length, is that naturalists see in it 
a resemblance to the crab in its young, or larval, state. This is only in accordance with a law, known 
as the law of recapitulation, that living animals in their younger stages show resemblances to extinct 
animals of long ages ago in their adult state. Naturalists have also noticed a close resemblance to 
land-scorpions and spiders. We may, therefore, not be far wrong in venturing to call these creatures 
Sea-Scorpions. 
IWOUUPSIES 
BY G. F. CHAMBERS, F.R.A.S. 
Eciieses of the Sun and of the Moon are totally different in principle A total eclipse of the 
Sun implies that the Sun totally disappears from sight: a total eclipse of the Moon implies that 
[by Lucien Rudaux. 
THE ECLIPSE OF THE SUN, APRIL 17th, 1912. 
If lines be drawn touching the surfaces of both Sun and Moon and extended till they touch the surface of our globe these 
lines will be found to form a cone. Now that part of the cone which is between the Moon and the Earth will be in deep 
shadow, for the Moon will have eclipsed the Sun’s rays, and it is at the point on the Earth that forms the apex of this shadow- 
cone that a total eclipse will be observed. On April 17th, 1912, this point of the cone swept the neighbourhood of Paris at ten 
minutes past noon. 
