150 



THE YOUNG NATURALIST. 



I must not withold from you the fact, however, 

 that some able men incline to the belief that 

 this object is not organic, but I have ex- 

 amined a large number- of specimens myself, 

 and am of opinion that it belongs to the 

 organic world. After this we pass through 

 rocks thirty or forty feet thick in which there 

 are no traces of organic remains, no fossils 

 exist, or at least none have been found, but 

 we must not conclude from that, that there 

 never were any, for all traces of them might 

 have been obliterated by the intense heat to 

 which they have been exposed, just the same 

 as in marble, which is but one form of lime- 

 stone ; but all traces of fossils has been lost 

 by the volcanic heat to which it has been 

 exposed. We next come to a class of rocks 

 called the Cambrian formation. If you go to 

 Dublin, near the mouth of the river, you will 

 find the.ie rocks there containing fossils like 

 Figs. 43 and 44. The general idea is that 



43 44 

 Oldhamia radians, and Antiqua. 



these are Corallines. When you visit the sea 

 coast you will find among the red and green 

 seaweed something which looks somewhat 

 like a seaweed, but it is more the color of the 

 sand, and very brittle when dry. It is known 

 as •' sea mat." This is a coralline, and if you 

 examine it with a glass you will find that it is 

 covered with innumerable little pockets, and 

 in each one of these pockets lived a little 

 animal. If these fossils were true corallines, 

 they are higher in their organisaton than 

 either the hozoon or the Foraminifera. Some, 

 however, incline to the belief that they were 

 seaweeds, and I must point out to you one 

 fact. Plants have the power of feeding on 



mineral and gaseous substances, but animals 

 have not this power, they are dependant upon 

 plants for their support, so that plants must 

 have existed before animals, as animals could 

 not exist before plants. In this Cambrian 

 series we find the first traces of plant life in 

 the form of seaweed. The reason that sea 

 plants rather than land plants should appear 

 first is rational, as all the earlier animal life 

 was marine. Associated with these seaweeds 

 we find shells something like a cockle, but 

 yet very different from a cockle in their in- 

 ternal structure. Here in these ancient rocks 

 we find a small shell called Lingula, and it is 

 very curious that this little shell should have 

 gone on from the time these rocks were de- 

 posited, through millions of years, till now 

 perpetuating almost identically the same form, 

 for the Lingula of our present seas are almost 

 indistinguishable from those we find fossilised 

 in the Cambrian rocks, save only that the 

 point of our present ones is drawn out into a 

 long point. This is one of the anomalies we 

 meet with in geology, which the theory of 

 evolution has not yet explained. Here in the 

 lower Cambrian we just meet with sponges, 

 star fishes, and sea worms. In the upper 

 part of the Cambrian series we meet with the 

 remains of certain animals, something allied 

 to the king crab of the present day, but, as 

 Hamlet is made to say of his father's ghost, 

 they "come in such a questionable shape" 

 that we scarcely know what they are, but we 

 call them Trilobites, and have settled down to 

 the idea that they were crustaceans. We 

 find these animals in all points up to the coal 

 measures, and it seems that these were the 

 ancestors of the present king crab, which sup- 

 position is strengthened by the fact that while 

 the king crab is very different in its adult 

 state, it is very similar to the Trilobite in its 

 young state. Certain forms of shellfish like 

 our cockle and mussel now make their appear- 

 ance. We now cross the boundry line into 

 another system of rocks called the Silurian 

 rocks, and there find a still further change in 

 the animal life ; those animals to which I 



