THE FIRST APPEARANCE OF LIFE. 95 



believes it to be a low foraminiferon ; but later 

 researches make this very doubtful. The direct 

 examination of the deposit itself scarcely lends 

 support to the belief in its organic nature. It is 

 found in the lower Laurentian rocks, which are cov- 

 ered with thousands of feet of rocks less metamor- 

 phosed than those containing the Eozoan, and yet 

 themselves containing no fossils. It now appears, 

 also, that this so-called fossil is sometimes found in 

 veins in the rocks, and this position is utterly 

 impossible for a true fossil. These facts, therefore, 

 render it improbable that the Eozoan is any thing 

 more than a mineral deposit ; and lead to the con- 

 clusion that the first traces we have of life begin 

 with the Silurian age. But whether it be a true 

 animal or not, does not materially affect the difficul- 

 ties surrounding the sudden appearance of a highly 

 differentiated fauna in the very beginning of the 

 Silurian age. The first record we have of life is 

 very surprising. Instead of a few low forms of life, 

 instead of a few synthetic genera, the Silurian age 

 was supplied with a highly developed fauna of 

 comparatively highly organized animals. All of 

 the great types were represented : Coelenterata, 

 Polyzoa, Brachiopods, Echinoderms, Mollusks, 

 Worms, Arthropoda ; and the late discoveries of 

 Claypole have traced the vertebrates not indeed to 

 the bottom of the Silurian, but to the bottom of 

 the upper Silurian rocks, a number of remains 

 proving that fishes were then in existence. Within 

 a few months two scorpions have been added to the 

 Silurian fauna, adding another class to the already 



