^HE SURVIVAL OF fHE FirrESt 107 



glimpse somewhat before the beginning of Palaeozoic time. 

 Our chronology is none too definite, our view distant and dim. 



At this time a very large part of the globe was covered by 

 a vast primeval ocean. The continents were hardly outlined. 

 North America seems to have consisted mainly of a V-shaped 

 mass of land with its apex near Lake Superior and its arms 

 stretching, one toward Labrador, the other toward Alaska, to 

 the east and west of Hudson's Bay. The eastern and western 

 edges or rims of the continent were marked by uplifts in the 

 region of the present Appalachian and Cascade ranges. 

 We do not know how much life there was upon the land. Our 

 ancestors seem to have been living in the primeval ocean; if 

 they were then living in fresh water, it would not greatly af- 

 fect our conclusions. 



Mollusks were well represented in nearly or quite all their 

 great divisions. Clams, safely ensconced, slumbered in the 

 mud. Other forms with spiral shells crawled on the sea- 

 bottom. Cuttlefish, somewhat like our present squids, but 

 with their bodies protected by a light shell, swam freely every- 

 where. They seem to have lacked the parrot-beak of modern 

 forms. This lack was no serious defect; they could swallow 

 any of their competitors whole. 



Crustacea, now represented by crabs and lobsters, crept or 

 swam, had jointed legs, and facetted eyes, and were somewhat 

 protected by a coat of Hght plate armor mainly used for the 

 attachment of muscles. 



Swimming in the water above, possibly banished to fresh- 

 water, were animals perhaps as large and as dangerous as small 

 earthworms. They were kept away from the rich feeding- 

 grounds of the seabottom by crabs and mollusks. They lived 

 on the minute forms of life which they could sift from the 

 water. These were the primitive chordata, ancestors of the 

 vertebrates. Fascinating worms were abundant, and prob- 

 ably other interesting forms. These we must neglect. They 

 do not concern us and have mostly died out. 



Can we pick the winner? Which of these competitors is 

 the fittest, most likely to survive and hold first place. We 



