STAR-FISHES AND SEA-URCHINS. 57 



flower-cup was a kind of Star- Fish, growing upon a tall 

 stalk, which must have been attached to the ground 

 when the creature was alive. And so they were no 

 longer considered as flowers of old times that had been 

 hidden away in the rocks ; and they lost their pretty 

 name of " stone lilies," and are now called Crinoids, 

 the first animals of this kind that ever lived. 



You will wonder, perhaps, how we know that they 

 were the first. We know it because they are found in 

 very ancient rocks, where are preserved the impres- 

 sions of a variety of animals that lived many thousand 

 years ago. Among them are Corals, Star-Fishes, shells, 

 worms, queer crabs, and strange fishes, old-fashioned 

 creatures very unlike those living on the earth now ; 

 creatures that vanished away many, many centuries 

 ago, leaving their traces in the rocks to tell us 

 something of the story of those old times, before man 

 and the animals living with him upon the earth were 

 born. And perhaps you may ask another question, 

 how it happens that any animals could be preserved in 

 hard rocks ? At the time these animals were buried 

 there, the rocks were not hard. Many of our rocks 

 were mud or sand at first, and have become hard only 

 in the course of time, from the continual pressure of the 

 layers of mud and other materials constantly added 

 above them year by year, till the whole mass is consoli- 

 dated into rock. Now, during this process, which may 

 last for centuries, many animals die in the soft mud or 

 sand ; and, when it afterwards becomes hard, the solid 

 parts of their bodies are preserved there, and are thus 

 built, as it were, into the rocks. There are still among 

 the living Star- Fishes a few forms * resembling those 



* Pentacrinus and Comatula. 



